CATT-Acoustic v8/v9 Users' Page
Document last updated:  ,  Bengt-Inge Dalenbäck

What's new?
The  bug-list is continuously updated
(any important bugs are notified via the mailing list)


CATT-Acoustic v9.1 with TUCT v2


For more details and a bare-bones list of v9.1 news see What's cooking?

Training course in the UK


Adrian James Acoustics now again offer a CATT-Acoustic Training course

Adrian James set up the consultancy in 1994 to specialise in the acoustic
design and refurbishment of performance spaces. Since then AJA have
used CATT-Acoustic on a vast number of projects.

TUCT v1.1a:4
including CATT-A v9.0c:3
Fix: TUCT v1.1a:4. In a few cases an early buildup has been observed
in the impulse response (h) using Predict SxR algorithm 1 (also when
using split > 0). This behavior is corrected.

  • Prefs option to select dialog font type and size (thereby also
    changing the dialog size)
  • Prefs option to select graphics font size
Included in a v9.0c:3 updates and installations,

TUCT v1.1a:3
maintenance update

Maintenance fix: TUCT v1.1a. Minor diffraction issues when modeling
side-by-side planes instead of modeling the intended way using sub-divisions.

Minor addition: Time Trace Save AVI uses a well working compression,
see Help for further details.

Included in a refreshed v9.0c:2 updates and installations,

If v9.1c:2 is already used simply install the TUCT v1.1a:3 maintenance.

"Reverberation time, diffuse reflection, 
Sabine, and computerized prediction"
Part I and II

This is an on-line article originally published at the RPG Diffusors Inc.
web-site in 2002. The paper covers in more detail the topic in FAQ 3
and the principles hold also for v8 and v9 with TUCT.

TUCT v1.1a:3
maintenance update
see above

This maintenance did not actually include v1.1a:3 but still v1.1a:2
(but full updates and installation included  v1.1a:3). Use the corrected
update above.

Update and maintenance of the Tannoy_CATT DLL
for modeling of QFlex arrays.



UnCTT and unzip into your "CATTDATA"\Sd2Data\Tannoy_CATT folder.

Update for users with unexpired free updates (handles the QFlex 64 array):

   Prediction license  Full license

(the updated DLL will be included in future updates and releases).

Maintenance for users that have this DLL but have expired free updates:

   Prediction license  Full license

TUCT v1.1a:2
maintenance update
including CATT-A v9.0c:2

TUCT v1.0 h
, g
maintenance updates

Fixes TUCT issues reported via the bug-list. (odd behavior of mapping
on some PCs).
v1.1a:2 including CATT-A v9.0c:2, v1.0h:6, v1.0g:5.

Minor additions to 
CATT-A v9.0c:2:
  • Scale and viewing options in Interactive RT estimation making
    it easier to compare different absorption and/or scattering cases side by
    side (the options are kept across estimations). Sab/Eyr and 8k/16k is
    optional to display.
  • Audience mapping planes do not have to be specified (if no mapping
    is to be done)

  • Selecting source aim as a receiver position, for example
    A0  0  3  2 speaker.SD1 rec(13)
    where the source will be aimed at receiver 13. 
For further details see Help | View Manual Addendum after installation.

CATT-Acoustic v9.0c release
including TUCT v1.1a
with diffraction

TUCT v1.0 h, g, f maintenance updates


Brief info, for further details see Help | View Manual Addendum
after the update or first UnCTT Addendum v9.pdf:
  • A comprehensive treatment of early diffraction using a secondary
    edge-source method based on a discrete Huygens interpretation of
    Biot-Tolstoy. As a background a 20+ page whitepaper document
    is included in the documentation and discusses the implementation
    as well as diffraction in general. The white paper explains why this
    particular implementation was chosen instead of a screen formula
    that has many limitations and questionable applicability in room
    acoustics. The chosen implementation also gives considerably more
    than a screen formula could such as more correct reflections from
    small surfaces and also helps modeling concave and convex curved
    surfaces approximated by facets. Although the background is
    complex using diffraction in predictions is simply made via selecting
    it in the Predict SxR and Map measures settings dialogs and in the
    Diffraction options dialog which combinations to include. Still,
    diffraction is a very fundamental part of acoustics so the principles
    need to be well understood.
  • Open-plan office measures DL2 and DLf application notes
    with remade examples and the effect of diffraction.
  • To enable special tests and investigations it is possible to select
    a combination of early sound, including diffraction,  by entering 0, 1, 2
    or 3 as Number of  rays/cones in Predict SxR and Map measures
    settings dialogs.
  • Map measures results have a new Type Spectra were the total SPL
    1/1-octave spectrum as well as the SPL 0..10 ms and 0..50 ms are
    shown for each map point when the Shift key is held and the mouse
    is moved over the map (i.e. similar to the Echograms option).
  • Map measures map point coordinate mouse-over display
  • Map points optionally shown with (Audience mapping) / Surfaces
  • New mapping palette options (selected in Preferences): A smoothly
    modulated palette named R-G-B Modulated and a user-defined
    monochrome palette that goes from light to dark color named
    Color Luminosity
  • Some export additions: Tref, TSabine and TEyring
  • Utilities menu export of Predict SxR results will export
    modified STI and U-50 results
    . In previous versions text and MATLAB
    export did not export the effects of changed background noise or overall
    SPL change (Eqx) from Predict SxR but used the originally given data.
    Due to this the MATLAB export has some changed and new variables:
  • Predict SxR LF is now calculated both for E and h and the previous
    h-based LF has been corrected (see below)
  • Optional grid on Show 2D Plan/Section (selected in Preferences)
  • Explicit selection of number of threads to use in processing
    (selected in Preferences)
    . The number of threads can be selected as
    auto,1,2,3,...,16). auto corresponds to previous versions that sets it
    to the number of
    processor cores Windows reports (typically the most
    efficient choice)
  • If no direct sound then the Show3D: line  S->R with SxR spheres is
    dashed green and says "No direct". Applies also if no direct sound is
    included in special test options as discussed above.
  • Map measures STI dialog change/addition: The ISO 3382:3
    (Annex B) “Minimum Change in Task Performance” derived from STI has
    been implemented and the STI dialog now has a Show: list-box where
    either STI, CIS or MCiTP can be selected. MCiTP is also added to the
    selection of batch map exports and Statistics is enabled.
  • Absolute Predict SxR impulse response displays with variable
    scales (LMB up/down).
  • AUDABS and AUDABS1 - new indirect options to specify audience
    . Two new directives AUDABS and AUDABS1 that work the same
    way as ABS and ABS1 but when used in a plane definition they will
    indicate that the plane is an audience area mapping plane in the CAG-file
    exported for TUCT
  • Optional TAB-delimited copy of results from Interactive RT estimation.
    When the Statistics or OK button is clicked the results can be selected
    as a readable text-file, as in previous versions, or copied as TAB-delimited
    text to the clipboard for pasting into a spreadsheet.

A v9 installation can be updated or installed from scratch.

For users with expired free updates (see Help | About)  TUCT maintenance
are available (include all previous fixes):

Current maintenace fixes (v1.0h:5, v1.0g:4, v1.0f:6):
  • (g,h) CATT-Edit Help menu attemped to load the old catt32.chm file. 
  • the 3rd order B-format N and O has changed, for details on old
    versions < v1.1a see the bug-list.
  • (h) The direct sound ("free field") for DLf and DL2 measures did not
    include air absorption. Of little practical consequence since according
    to ISO 3383-3 these measures are to be A-weighted and the direct
    sound distance are short.
  • (f,g,h) The h-based Predict SxR LF was not predicted well for rather
    complex reasons but is fixed and v1.1 will also have an E version. LF
    is a very sensitive measure also for measurement, a good example is
    from the 3rd Round robin (PTB studio) where the measured value for
    one position varied between 8-35% at 125 Hz and 19-37% at 500 Hz
    depending on the measurement group.
  • (h) The DLf and DL2 measures can sometimes use the wrong selected
    band. It occurs if the band is changed while viewing DL measures. 
  • (h) STI female voice had an error in the beta functions that if it hit was
    obvious (the 125 Hz MTI value dropped to zero). It appears that female
    voice is used quite seldom especally since STI-Pa is only for male
  • Some minor additions
Previous maintenace fixes (v1.0h:4, v1.0g:3, v1.0f:5 120410):
  • The 1st order ISM in Predict SxR may in some types of rooms
    with many internal blocking walls or objects give false reflections.
  • Some minor additions
Previous maintenace fix (v1.0h:3 120223):
  • Sequence processing and a small addition indicating each
    step-files' basic settings.
  • Walker.exe update (full version), the exe first included in v9.0b:1
    required an external DLL that was not included.
Previous maintenace fix (v1.0h:2 111220):
  • Masking for 4th edition STI

CATT-Acoustic v9.0b

including TUCT v1.0h
  • A more responsive PC during calculations
  • A Lambert 1D scattering function for walls with battens
    and 1D-diffusers
  • A novel and flexible mapping implementation of the DLf
    and DL2 measures
    (ISO 14257) suggested for use also
    in open-plan offices (draft ISO 3382-3) that allows these
    measures to be used as design tools where the
    limitations and pitfalls also can be understood.
    Comprehensive application notes.
  • T-30 statistics for selected source and receiver combinations,
    useful for understanding room properties

  • a recline() function for placing receivers in a line (useful
    for DL2 and DLf)

  • STI optionally according to IEC 60268-16 4th edition (2011)
  • Sequence (batch) processing now also in TUCT
  • Export (to spreadsheet) of a selected set of maps from
    Audience mapping
  • Creation and export of ITU 5-channel impulse responses
    now also in TUCT, many options ranging from actual mic
    setups (INA5, OCT, MMA etc.) reflection by reflection to
    three ways as a post-process from B-format using the
    patented BPhormer
    process, the Sector mic and
    basic coincident patterns
  • Export of various mono mic impulse responses (omni,
    cardioid, supercard, hypercard, fig-of-8) 
  • Graphics copy/save/print options also with minor dialog
    graphics such as map statistics
  • Predict SxR algorithm selection tips on the settings
  • Time Trace "fast forward" skipping over time segments
    of little interest
  • Loudspeaker sensitivity variables that can be used in
    the source file
  • Optional auto-viewing of saved PL9-files in TUCT
    (useful for saving temporary results for later viewing/export
    or comparisons)

  • MultiVolver WCP addition for faster selection of multi-
    channel WAV input.
CATT-Acoustic v9 printed manual shipped

The manual includes the main CATT-A
and TUCT manuals in one binder

The printed v9 manual has now been shipped to all users that had
unexpired free updates July 5 at v9 release. Users updating from
v8 will receive the v9 manual.  

Fix for CATT-Edit under Win 7

Some earlier versions (before Win 7) misinterprets the Windows version
and puts a limit to the size of files that can be loaded. Free for all licenses,
run the installer (since Vista it can be hard to simply copy a file to the
Programs folder)

The Common Loudspeaker File format

CLF2 v2 update released
  • CLF2 v2 introduces phase and optional filters for beam-steering
    and/or cross-overs and multiple files are used to describe an
    array or a multi-way loudspeaker. 
  • As CLF2 v2 files appear CATT software will support the new
  • To update your viewer and see CLF2 v2 sample files go to

Fix for DXF2GEO v1.0f (in v9)

DXF2GEO has required very few updates after release so with the
recompilation to get v9 icon colors it was forgotten that meanwhile a
change had occured in the 3D libraries. Typical symptoms a crash when
"Show both sides" and that the display would have triangles when there
should be 4-corner FACEs. This affects the display only, not the export
to GEO. A fixed version can be downloaded replace the one in your
CATT folder.

CATT-Acoustic v9
including TUCT v1.0g

CATT-Acoustic v9:
  • The Prediction module is renamed to Modeling module and
    all prediction and auralization except Interactive RT estimation
    are removed, further prediction/auralization now only in TUCT
  • v8 PRD-files can be loaded but will be saved as MD9, the
    new basic modeling project settings file format for v9.

  • New PL9 graphics for geometry view/check
  • The PL9Viewer module is almost identical in terms of menus
    to the old Viewer module but is totally new (based on the
    standalone PL9Viewer and TUCT
    graphics libraries)
  • The Directivity module is identical but creates new PL9
    graphics with some changes, especially to the polar
  • Update ActiveAudio DLL adding the Ray-On 100 array model
  • The Surface properties module is identical.
  • The Post-processing module is removed, what remains of
    interest is now under a new Modeling:Extras menu.
  • the Sequence processing module is removed.
  • the Source addition module is removed.
  • new Introduction Manual (Help menu).
  • New CATT-A + TUCT pdf manuals
  • New  CATT-A + TUCT  printed manuals both in one binder
    - will be sent out in September.
Includes the 4th major update of CATT TUCT:
  • Map measures results have a new Type Echograms were an
    echogram is shown for each map point when the mouse is
    moved over the map. 
  • In Window | Image Source Model the left Ctrl is held when
    selecting Show all paths only the wall hits will be shown.
  • A new help/manual section indicates hidden features such as
    the one above when holding Ctrl (see 4.2 Hidden options)
v9 can be installed as an update to a current v8 installation or installed
from scratch

v1.0f:3 maintenance update

Free for all TUCT v1.0f users

A maintenance update of TUCT v1.0f that fixes issues below:

Minor fixes in v1.0f:3 110705

Fixed in v1.0f:2 110325:
  • use of a source roll angle would sometimes give the wrong
    rotation, the maintenance also includes catt32.exe v8.0k
    build 2.02 since the roll problem was also due to the CAG-file
  • the mean free path would be the estimated slightly too short
    if the model e.g. was very flat
    , affected T-Sabine and T-Eyring
    but no other predictions
  • some small fixes
Since this relates mainly to fixes this TUCT update is free for
everyone that has free updates expiring on or after February
4 2011 when TUCT v1.0f was released.

TUCT v1.0e:5 maintenance update

Free for all TUCT v1.0e users

A maintenance update of TUCT v1.0e that fixes issues below:

Minor fixes in v1.0e:5 110705

Fixed in v1.0e:4 110325:
  • See v1.0f:2 fix above
Fixed in v1.0e:3 110204:
  • dBA and NC update also when manual entering of noise
    in U50 and STI dialogs
  • improved Meta export
  • Misc. minor interface fixes
Fixed in v1.0e:2 101210:
  • Map measures and Map direct could randomly give strange
    results but only on some PCs. Symptoms could vary but a
    common denominator was that the results were clearly
    unrealistic. The reason was the intricacies of multi-threaded
    parallel processing that behaved differently on different PCs. 

Since this relates mainly to the fixes this TUCT update is
free for everyone that has free updates expiring on or after
Oct 29 2010 when TUCT v1.0e was released.

v1.0d:6 maintenance update

Free for all TUCT v1.0d users

maintenance update of TUCT v1.0d that fixes issues below:

Minor fixes in v1.0d:6 110705. This is the last maintanece of v1.0d

Fixed in v1.0d:5 110325:
  • See v1.0f:2 fix above
Fixed in v1.0d:4 110204:
  • dBA and NC update also when manual noise entering in
    U50 and STI dialogs
  • improved Meta export
  • Misc. minor interface fixes
Fixed in v1.0d:3 101210:
  • See v1.0e:2 fix above
Fixed in v1.0d:2 101029:
  • Map measures with interference on could give wrong results in
    some cases. It appears that the differences were not easy to
    spot but took a special synthetic case for it to be clearly seen.
  • the hidden option to allo use of all reporetd cores did not work
    as documented especially not with hyperthreading.
Some v1.0e additions added to v1.0d:2 :
  • all models are rotated around their centers (as in 3D-viewer and
    CATT-Acoustic PLT)
    instead of the origin.
  • due to diffuse reflection being handled by a stochastic process
    two runs with the same room and the same prediction settings
    will always give slightly different results but from this version the
    Map measures algorithm has been improved to lower the variation.

Fixed in v1.0d release 100921: Further fixes not likely to have affected
except in special cases and was never seen in normal rooms but only
in a stadium case, the syptom was that the pressure-based direct
sound looked like it became much too strong.

Fixed in v1.0c release 100819: Since release of TUCT there have been
a handful of cases reported where these algorithm options have created
strange results. The symptoms have been that some reflections became
clearly too strong but it has been difficult to find the reason for this since
it was only obvious in some special cases and almost only if really
many rays were used. However, a case was finally reported where it
was possible to simplify the model with the problem still remaining so it
could be investigated and fixed.

Since this relates mainly to the fixes this TUCT update is
free for everyone that has free updates expiring on or after
March 29 2010 when TUCT was released.

Update of the ActiveAudio StepArray DDI module
SA400P and SA180S added
The SA400P and SA180S models are added. It will be included
in subsequent CATT-Acoustic update but can be downloaded in advance
(requires unexpired free updates). UnCTT and UnZIP the contents in your
current "CATTDATA"\Sd2Data\ActiveAudio_CATT folder overwriting old files.

Update of the Nexo GEO DDI module
Geo S12 added
The Geo S12 model is added. This DLL will be included in subsequent
CATT-Acoustic updates but can be downloaded in advance (requires
unexpired free updates). UnCTT and UnZIP the contents in your current
"CATTDATA"\Sd2Data\NexoGEO_CATT folder overwriting old files.
Update of Nexo SD1-format
directivity files
Download and unzip to your "CATTDATA"\SD folder or a sub-folder.
B-format microphones
A list of available B-format microphones can be found here. If there are
any further mics to include please send an e-mail.

New DDI module for
Tannoy QFlex
DSP-steered arrays

A new DLL Directivity Interface (DDI) module for Tannoy QFlex array and
included in subsequent CATT-Acoustic updates. This DLL does not allow
for entering the steering parameters directly but relies on data generated by
the QFlex BeamEngine

Tannoy_CATT.CTT  (2,876 kB)

Requires unexires feee updates. Run UnCTT and UnZIP the results
in a folder "CATTDATA"\Sd2Data\Tannoy_CATT

v8.0j build 2 is released

Including the first update of

100629 The first major update of the new CATT TUCT software includes a
range of useful additions:
  • Saving/loading named 3D views, global or project specific
  • Shortcut to load a new project using the same 3D-view
    as the current
  • Project-based automatic saving of the latest used settings
    for Predict SxR, Map direct and Map measures
  • Simpler scrolling through Predict SxR results
  • Different internal Predict SxR algorithms are used
    depending on case, no more memory issues with many
    receivers and/or long echogram/IRs
  • An additional normalized Schroeder plot showing the
    decay for one band against a backdrop of all bands
  • An interactive option to show only the energy echogram
  • An STI limit can be specified for STI maps indicating
    which positions are below the limit
  • Optionally suspend update of a big map while changing
  • Map spreadsheet export with automatic separation into
    layers that cover eachother in z (such as a balcony
    above a floor audience)
  • Seperate map z-layer displays (show balcony by itself,
    floor by itself or both)
  • Time trace includes diffuse reflection as well (it was initially
    not included since it often creates a too confusing display
    but has its uses)
  • Several small useful additions and changes

Many new HRTF sets
091217 After considerable processing all the LISTEN project HRTFs
have been converted to CATT-format (requires v8.0i:2 due to
a new angular resolution). Because of the big total size (102
sets, 74.5 MB
) these HRTF libraries are not included in
installations or updates but can only be downloaded.

More anechoic recordings
090925 The Dipartimento di Ingegneria Università di Ferrara, Italy
have made available a set of anechoic recordings of islamic
songs, byzantine songs from CAHRISMA project and a set
of anechoic ancient greek songs and music from the
ERATO project. Non-commercial use only.

Multiple CPU core processing

v8.0h and above will benefit from multipe cores if the cores
are all on the same chip. The most common useful hardware
would be a quad core while a dual quad core (i.e. 2 x 4 cores)
actually may run slower than a single quad core (will be
addressed in the next release so that it will run at the speed
of a single quad core). To benefit form multiple cores on
different chips requires a much more complicated programming
and is not planned.
More anechoic recordings
The Helsinki university has made new anechoic recordings
publicly available.
GratisVolver 081001 update v1.4a with 4-channel convolution (typically B-format IRs).
A list of some available
measurement software
As a service to users, a list of some available room
acoustics measurement software has been assembled.
GratisVolver 080321
update v1.3c with enhanced IR viewing and graph copy.
CLF Software update
071212 New display options for balloon and polar viewing, and more.
New printed and PDF manual

070918 A new printed manual has been created covering all additions
v8.0g:2. New purchases or updates include the new
manual and all with
unexpired free updates will receive the new
manual by mail during September.
update v1.0b loop options added.
The FIReverb Suite 4th Ed. update. 070518
Included with full v8.0g version and later updates
3rd party software and tools 070228 SketchUp plugins, MATLAB utilities
Links to anechoic music
New CDs, CDs out of print and internet links.
Fogg Art Museum Lecture Room
links to paper and models for download
"A calibrated recreation of the birthplace of Room Acoustics"
A Forum Acusticum Budapest 2005 paper with predictions
and auralizations of this famous auditorium.
Surface properties library
from RPG Diffusor systems

A range of  surface propertis from RPG diffusors and other
acoustic materials.
The Common Loudspeaker File format
(a.k.a. the CLF)
is released!
The CLF has been released. For a background to the CLF,
and download of a free viewer with sample files, go to the
CLF web page:
For CATT-related CLF-info go here.
Free software
A convolver for mono or stereo WAV-file impulse
responses (IRs). WAV-file playing (individual
playing of input file, IR and processed file). A self-
contained small software specially made to encourage
viewing and listening to IRs and convolving with
anechoic/dry music. If placed in the CATT-folder it
will be on the File|External CATT Tool menu
(from v8.0e) .
Epidaure GEO converter
A first beta version of Epi2Geo has been completed.
Can CATT-Acoustic handle coupled rooms?
In what cases the various prediction methods employed 
can be expected to work well, and a note about a new 
RTC variant under development for coupled rooms.
EXP2SD1 converter update
EASE v2 text EXPort-file loudspeaker data converter.
Can now convert files both for v7 and v8.
EAS2GEO geometry converter
EASE v3 geometry export conversion to CATT
Instrument directivities available
from PTB, Germany
PTB have made available 13 different directivity 
files in CATT SD1-format for orchestral instruments
plus singing voice.
Surface properties from PTB
PTB have made available many materials in Excel
More info on diffusion (scattering)
Recent activities with ISO and AES has resulted
in some available data and a measurement
procedure for diffusers. FAQ 3 is expanded.
Absorption data
7 import libraries (163 materials)

What's cooking?

Development of the next major release v9.1 with TUCT v2 is now close to release February 2016) but is still available for beta testing or receiving the extensive unoffical preview (contact CATT).

The central news
is a fundamental improvement of how sound sources and arrays are handled but TUCT v2 also has a range of general additions. The DDI interface will no longer be developed but array modeling will instead be based on a new flexible array file format that also can handle curved line arrays with high-frequency line elements.

For just the basic info a bare-bones list of the v9.1 news can be downloaded here

What's old (but still important)?
Update/UnCTT  problems?
UnCTT may need an update.
Update mailing-list
be notified about updates/bugs!

Read this!

This page contains a variety of items supporting CATT-Acoustic v8 and v9 users. Most download material uses a private CATT file-format with the extension .CTT from which files can be extracted only if a valid and (in some cases) non-expired CATT-Acoustic license is installed (they may be ZIP-ed for faster download, use WinZIP for safest unzipping).

If CTT-file extraction fails it may be because:

Dates on this page are given in yymmdd format (e.g. 991221 means Dec 12, 1999) and yyyymmdd when necessary. An exception is the document change date at the top that may use mm/dd/yy.
Note for those that are not licenced CATT-Acoustic users
Even if this page is for CATT-Acoustic users it is an open page. 
If you are interested in the software, check the main CATT page
where also a demo can be downloaded.

The demo does, however,
not give a possibility
to extract CTT-files referenced on this page.


[Update mailing list] [Do I need to update] [Update problems?] [Update cost and options]
[Update CATT-Acoustic/TUCT]
[The FIReverb Suite]

Do I need to update?

Sometimes an update may be unnecessary since it just corrects a bug or problem that to some users may be of little consequence. A short document that lists known bugs in each version (and sometimes its solution) can be downloaded below before updating. However, even if no bugs have appeared it may still be a good idea to update because of useful additions to the software as given in the addendum below. These CTT-files do not require unexpired free updates. If you have problems running UnCTT on these files see update problems.
Known bugs and fixes for v9.0
for >= v9.0a

Known bugs and fixes for v8.0 and TUCT < 1.0g
for > v8.0g:2
for <= v8.0g:2
(a few kB in download size)

Main application (CATT-Acoustic)

Updates with additions and bug-fixes including an up to date Manual addendum  (addendum v9.PDF, see Help menu for viewing) and help-file.

Main update files for updating v9.0a,b,c
Running UnCTT on these update-files extracts an update installation program at a selected location. After UnCTT run the update installer. A "Mini" update (if any) is a small download that only contains small fixes of the current release and must be added after the main release.

Note if you are updating v8 to v9: It is not possible to install v9 separately on a PC with v8 but it is possible to install v9 over a current v8 installation, same folder, but the v8 and v9 main programs cannot be run at the same time. v8 and v9 will then share Preferences for common items, such as Project folder and Surface properties library that anyway would be the same, but will not interfere with each other
. If v8 is updated to v9 the old data libraries should be updated but will still be called "CATT-Acoustic v8.0 library files", there are no special changes to the data libraries for v9. Only new v9 file-types (MD9,PL9) can be loaded by clicking in Explorer, other files are already registered to v8 and have to be loaded from within CATT-A v9. All in all for v8 users it is better and recommended to install v9 fresh via the full installation files, the v9 installation includes the v8 PLT-viewer so that old results PLTs can be viewed and old project PRDs can be opened. If necessary it is better to keep a v8 installation on another PC.

Your License
Prediction pred_update_v9.0c_build3.CTT free up-
dates to



24,514 kB Includes  TUCT v1.1a:4
Full auralization full_update_v9.0c_build3.CTT 35,557 kB

TUCT v1.1a maintenace update files
The updates below are intended only for users that have TUCT v1.1a, they contain reported bug
fixes and minor new additons. Running UnCTT on these update-files extracts an update
installation program at a selected location. After UnCTT run the update installer.

Your License
pred_maintenance_TUCT_v1.1a3.CTT 140807
TUCT v1.1a:3
also includes
CATT-A v9.0c:2 exe, help and addendum.
This is the last maintanece of v1.1a:3 and below
Full auralization
full_maintenance_TUCT_v1.1a3.CTT 13,742

TUCT v1.0h maintenace update files
The updates below are intended only for users that have TUCT v1.0h but whose free updates
have expired
after Dec 2 2011, they contain reported bug fixes and minor new additons.
Running UnCTT on these update-files
extracts an update installation program at a selected location.
After UnCTT run the
update installer.

Your License
pred_maintenance_TUCT_v1.0h6.CTT 130417
TUCT v1.0h:6
This is the last maintanece of v1.0h
Full auralization
full_maintenance_TUCT_v1.0h6.CTT 7,506

TUCT v1.0g maintenace update files
The updates below are intended only for users that have TUCT v1.0g but whose free updates
have expired
after July 5 2011, they contain reported bug fixes and minor new additons.
Running UnCTT on these update-files
extracts an update installation program at a selected location.
After UnCTT run the
update installer.

Your License
pred_maintenance_TUCT_v1.0g5.CTT 130417
TUCT v1.0g:5
This is the last maintanece of v1.0g
Full auralization
full_maintenance_TUCT_v1.0g5.CTT 6,988

TUCT v1.0f maintenace update files
The updates below are intended only for users that have TUCT
v1.0f but whose free updates
have expired
after Feb 3 2011, they contain reported bug fixes and minor new additons.
Running UnCTT on these update-files extracts an update installation
program at a selected location.
After UnCTT run the update installer

Your License
pred_maintenance_TUCT_v1.0f6.CTT 121122
TUCT v1.0f:6
This is the last maintanece of v1.0f
Full auralization
full_maintenance_TUCT_v1.0f6.CTT 7198

TUCT v1.0e maintenace update files
The updates below are intended only for users that have TUCT
v1.0e but whose free updates
have expired
after Oct 29 2010, they contain reported bug fixes and minor new additons.
Running UnCTT on these update-files extracts an update installation
program at a selected location.
After UnCTT run the update installer

Your License
pred_maintenance_TUCT_v1.0e6.CTT 111202
TUCT v1.0e:6
This is the last maintanece of v1.0e
Full auralization
full_maintenance_TUCT_v1.0e6.CTT 6948

TUCT v1.0d maintenace update files
The updates below are intended only for users that have TUCT
v1.0a-d but whose free updates
have expired after
March 29 2010, they contain reported bug fixes and minor new additons.
Running UnCTT on these update-files extracts an update installation
program at a selected location.
After UnCTT run the update installer

Your License
pred_maintenance_TUCT_v1.0d6.CTT 110705

TUCT v1.0d:6
This is the last maintenance of v1.0d
Full auralization
full_maintenance_TUCT_v1.0d6.CTT 6417

Update problems? Your UnCTT may be too old

Update cost and options

The FIReverb Suite (full license)

The FIReverb Suite 5th edition stadalone was released Oct 2010 (v8.0k full version includes 5th edition). It will run under a full CATT-Acoustic license or under a stand-alone FIReverb license. Note that if someone with the prediction license is interested in testing The Suite a 30-days trial license can be issued. See main page for information on and initial download of the standalone Suite.

The Suite has its own support page:

Important note: The Suite is considered an upgrade and to have it run in full mode, your full-version CATT-Acoustic key must not have expired. You can still install and see how it looks but it won't do anything really useful. As soon as an updated key is installed it will run in full mode, contact CATT or your distributor for an upgrade.

A comprehensive audio demonstration/tutorial with stereo  5-channel upmix and other examples is available.

Update mailing-list

If you wish to be notified each time the users' page is updated in a significant way (e.g. a software or tool update or other important info),  send an e-mail and give the e-mail address you prefer to be notified on. Your address will not be visible to other users that receive the same update message. Note: if the bug-list is updated with only a low-significance bug a mail is not sent.

Update problems?

Note that if you can't update it is typically because your free updates have expired and not because of UnCTT problems (Help | About or the UnCTT dialog regarding when your free updates expire). However, due to several internal license mechnism changes and the change to use of a .DAT license key-file, an old UnCTT may no longer work, or it may create a corrupt file after extraction. If you do not have an UnCTT at least v1.0k send an e-mail to CATT   and you will get a link to a new version (due to security reasons UnCTT is not availble for direct download).

Installs (for users with unexpired free updates)

Full installation
Running UnCTT on these CTT-files extracts a full installation program at a selected location.
After UnCTT place your current Xtra32.DAT from the CATT-folder in the same folder as the
installer and run the installer. Any previous installations of CATT-Acoustic and data
libraries have to be uninstalled after having backed up any "CATTDATA" files created
(typically in
\ABLIBS, \SD and possibly \ANECHOIC for full version users).  After
installation these files can be put back in the same locations in the new "CATTDATA".

Your License
Prediction pred_Install_v9.0c_build3.CTT free up-
dates to




24,524 MB Includes  TUCT v1.1a:4
Full auralization full_Install_v9.0c_build3.CTT 57,268 MB

Concept Halls (all licenses at any time)

Work has started on creating a series of well documented parametrically designed models of each basic type of room that may be of interest to study using CATT-Acoustic. The series has been called Concept Halls because one of the anticipated uses is to test ideas and concepts that may not require a model of a particular existing room but only of a room of a particular type. Such models can also be very valuable in room acoustics education. If a user has made something he wishes to share, send the info to CATT.

Types that can be interesting to create one or more generic models for are:

Hopefully, some of the models will be sophisticated enough to be used also as good representations of, or starting points for, models of actual rooms.

Underground station #1

This model consists of a generic Underground station designed so that the following parameters can be varied: length, width, height, trains:on/off, ceiling:flat/arched, ceiling arch type,entrance:size/location, platform width, train size, track width, upper/lower wall properties etc. This model is simple enough not to warrant any other documentation than the GEO-file itself.

Factory #1

This model consists of a generic  factory designed so that the following parameters can be varied: length, width, height, wall angles and upper/lower wall properties. Sizeable and moveable box objects that can mimic machinery can be moved around with sound sources automatically following. This model is simple enough not to warrant any other documentation than the GEO-files themself but is not a good model for real calculations since the floor under each "machine" is not removed (it was made so students easily could move them around). This model was made mid 90ies and since then the care about model correctness has increased.

Listening room #1

This model consists of a generic home theater designed so that the following parameters can be varied: length, width, height, soffit size, corner construction, upper/middle/lower wall properties, easy sound source placement for various kinds of surround. Contains PDF-file documentation.

Surface properties (all licenses at any time)

The files below are in CATT exchange TXT format and can be edited before import to the Surface properties library, e.g. to change some names or categories. Each CTT-file is small and fast to download. The CTT-files extracts to TXT-files in the CATT-folder ABSLIBS and can the be imported.

Note: with new v8 purchases the TXT-files below are already installed in the CATT-folder\ABSLIBS and a library containing all properties have been created (ABSLIB0_full.DAT, to use it just select it in Preferences).


Architectural/Room Acoustics text-book references

Download Description
RPG import library
RPG diffusers and other properties. Since this library
may contain duplicates of other libraries, the text file
can be edited before importing. Another option is:
  1. select Utilities|Create New Library As
  2. close the current library
  3. select the new library in File|Preferences
  4. load the new library and delete most of its entries
  5. import the complete RPG library and delete not
    wanted entries
  6. export the remaining entries to say RPG2.TXT
  7. close the new library (save not necessary)  
  8. select the old library in Preferences again
  9. import RPG2.TXT and save. 
For questions e-mail
 Michael J. Jarzabkowski
RPG Diffusor System Inc
PTB has made available a library Excel format, 2000 materials, names/descriptions
in German. Link changed 121108.
Misc. Misc.
French distributor Euphonia
markets a database AlphaBase
that can export to CATT format
Several hundred materials, names/descriptions in
Misc. Misc.
10 materials: mainly walls
"Architectural Acoustics"
Anita Lawrence
Ref. code: [Lawrence]
Elsevier Publishing Company Ltd.
10 materials: mainly audiences
"Room acoustics"
Heinrich Kuttruff
Ref. code: [Kuttruff]
Applied Science Publishers Ltd
London 1976, ISBN: 0 85334 573 2
3 walls
"Principles and applications
of room acoustics, vol 1"
L. Cremer, H. A. Mueller
Translated by T. Schultz
Ref. code: Cremer_Mueller
Applied Science Publishers
London/New York, 1982
ISBN: 0-85334-113-3
18 materials: chairs and  audiences
"Rumakustik", SBI-anvisning 
Joergen Petersen
Ref. code: [Petersen]
Statens Byggeforskningsinstitut
(in Norwegian, names translated)
29 materials: chairs and  audiences
"Sound absorption in Enclosures"
David B. Bies, Colin. H. Hansen
Ref. code: [Bies_Hansen]
Malcolm J. Crocker (Ed.),
"Encyclopedia of Acoustics"
John Wiley & Sons, Inc.
1997 ISBN: 0-471-80465-7
(all volumes)
20 materials: chairs and audiences
"Concert and Opera Halls
- How They Sound"
Leo Beranek
Ref. code: [Beranek]
Acoustical Society of America
1996, ISBN: 1-56396-530-5
73 materials: chairs, min.wool, cloth and audiences
"Akustik i rum och byggander"
Lennart Karlen
Ref. code: [Karlen]
Svensk Byggtjänst
1983, ISBN: 91-7332-226-1
 (in Swedish, names translated)

Directivity data (all licenses at any time unless a DDI update is required for SD2-files)

Each loudspeaker collection consists of a ZIP-file (after UnCTT has been run). The ZIP-file  is unzipped into the \SD folder and the speakers will be available for prediction including a collection file (for brands).

[Instruments] [Human voices]
[SD1 loudspeakers (validated)] [SD1 loudspeakers ("as is")]
[DDI (DLL Directivity Interface) modules]
[The Common Loudspeaker File Format (CLF)]

Instrument directivities (SD0 or SD1)

Instrument Download
Description yymmdd
Double Bass Grand Piano
From PTB Web-side SD1 PTB have made available 13 different SD1-format directivity
files for orchestral instruments. The format is SD1-TXT import.
Link changed 121108.
Important notes:
  • often these directivities do not include all octave-bands 125-4kHz so for non-existing band something resonable have to be selected. v8, extrapolates all non-existing lower or upper bands (also 8k and 16k) so these directivities will be a bit easier to use with v8. 
  • the axis of the directivity may not be the same as an anechoic recording of the same instrument. If the axis are different the eq of the source will be wrong but then the following trick can be used: 
    1. create an SD2 CATT_Generic ARRAY0 directivity with one element with that has the directivity of e.g. the Oboe.
    2. rotate the element so that the new axis is where the recording was made (use the aim coordinate).
    3. export as SD1.
    4. use the now rotated SD1 instead as source


This directivity is measured with the axis of the clarinet as source axis (and therefore has cylindrical symmetry) and does not include the player. To use it for auralization, an anechoic clarinet recording on the axis is required (note that the nominal Lp at 1m and Max Lp at 1m are not set to actual values nor are the source xyz extents).
Courtesy of PTB, Braunschweig, Germany. 

Human voice directivities (SD0 or SD1)

Voice Download
Singer From PTB Web-side,
see the Musical acoustics
SD1 PTB have made available a "singing voice" SD1-format
The format is SD1-TXT import
Important notes:
  • the axis of the directivity may not be the same as an anechoic recording of a song. If the axis are different the eq of the source will be wrong but then the following trick can be used: 
    1. create an SD2 CATT_Generic ARRAY0 directivity with one element with that has the directivity of e.g. the singer.
    2. rotate the element so that the new axis is where the recording was made (use the aim coordinate).
    3. export as SD1.
    4. use the now rotated SD1 instead as source
Singer (down)
Data copied from figures in the Acustica paper
"Directivity and Auditory impression of Singers"
by A. H. Marshall and J. Meyer, Acustica, v58, 1985, p. 130
The singer's axis (mouth) is directed ca. 25 degrees down in the manner singers often press their chin towards the chest.
Singer (onaxis)
As Singer (down) but rotated and exported to SD1 via the DDI
The singer's mouth is directed on the axis of the balloon. Updated because of error in Max Lp values.
See also FAQ on human talker directivities.

SD1 directivities supplied and validated by respective manufacturer

Manufacturer Download Description
Some Nexo models
Supplied and protected by Nexo.
All available model from Philips
Supplied by Philips. So far the source 3D extents (min-max box) has not been entered but have default values only.
000516: LBC3406/13 500 Hz Sensitivity / Lp1m_max corrected *)
L-Acoustics non-VDOSC models
000619 Supplied by L-Acoustics *)
Duran Audio
Duran Audio standard models 000323 Supplied by Duran Audio.So far the source 3D extents (min-max box) has not been entered but have default values only.*)

*) The data below is converted for v7 and does not contain the 8kHz balloon even it was present in the original data. v8 will extrapolate from 2k and 4k.

SD1 directivities supplied by respective manufacturer but not yet validated, provided "as is"

Note: The data below is converted for v7 and does not contain the 8kHz balloon even it was present in the original data. v8 will extrapolate from 2k and 4k.
Manufacturer Download Description
Meyer Sound Labs
Some models released by MSL
So far the source 3D extents (min-max box) have 
not been entered but have default values only.
d&b audio
 d&b audio models
000323 So far the source 3D extents (min-max box) have 
not been entered but have default values only
Peavy models
000323 So far the source 3D extents (min-max box) have 
not been entered but have default values only
Martin Audio
Martin Audio models
000323 So far the source 3D extents (min-max box) have 
not been entered but have default values only

SD1 directivities supplied by CATT-Acoustic users with access to EASE v2 data, provided "as is"

These files have typically been converted using the free CATT tool EXP2SD1.
Manufacturer Download Description
 No files yet - - - - -

SD2: DLL Directivity Interface (DDI)

A new directivity format (SD2) is available with v7.1 and e.g. offers array modeling (very high resolution distance dependent directivity) and a very general handling of directivity. SD2 offers a much higher degree of accuracy than the 10-degree "industry standard". The DDI interface is prepared for the new proposed high-resolution AES standard but lets a manufacturer offer high-resolution data even before a new file-format is agreed on. It also offers data hiding and hiding of intellectual property e.g. for DSP-controlled arrays or other special designs. For further details download a DDI white paper and viewgraphs from a workshop presentation at the Paris AES Feb 2000 (both in PDF-format).

The latest DDI modules are included in all update files. Each DDI module has its own dedicated help-file or PDF-file reached by pressing the Help button in the SD2-dialogs in the Directivity module. Note: a DDI-module update is considered a software update and requires a non-expired license key. 

This Outline_CATT DLL (April 1, 2004) was the first made using the sub-DLL concept where a manufacturer does not need to learn the complete DDI interface but only implements a sub-DLL with a few array modeling core functions. Anyone interested in the sub-DLL concept can request a dedicated white paper.

The Common Loudspeaker File Format (CLF)

The Common Loudspeaker File Format (CLF) was announced Oct 22 2004 and released Apr 15 2005.
For a background to the CLF, and download of a free viewer with sample files, go to the CLF web page:

CATT-Acoustic supports the CLF format from v8.0d by direct reading and use of the distribution binaries (.CF1 and .CF2).

HRTF libraries (full license at any time)

Additional libraries

HRTF Download Type yymmdd
ITA kunstkopf
artificial head
(629 kB)
(629 kB, converted from 
44100 Hz)
plain old
These are measured by Institut für Technische Akustik, RWTH Aachen, Germany from their new artificial head (the ITA Kunstkopf). The HRTFs give very good localization but also has a quite different sound from those originally supplied with CATT-Acoustic (CATT1_plain) that are measured from an individual and sound more neutral. 

v8 include these libraries on the installation CD.

artificial head
(315 kB)
(315 kB,converted from
44100 Hz)
diffuse old
These were measured by Bill Gardner and Keith Martin in 1995 at MIT Media Lab from the KEMAR artificial head by Knowles Electronics. The set chosen here is a diffuse-field equalized set where the effect of measuring at the "ear-drum" rather than at a blocked ear-canal entrance has, according to the documentation, been removed. Because the set is diffuse-field equalized it is reasonable to use it without a special headphone filter assuming that the headphone is diffuse-field equalized (quite common although exactly what a diffuse-filed equalization consists of hasn't been standardized). The KEMAR model used was a DB-4004 with DB-061 pinna (normal ear) but further details of the measurement can be found at the MIT  link

44.1k sets
(51 sets, total 19.8 MB)

48k sets
(51 sets, total 21.9 MB)

For background, details and listening please go to the LISTEN project web-site.

All the raw 44.1 kHz format sets have been processed, the effect of the mesurement chain has been removed, and 48 kHz versions have been created. Note that the horizontal angular resolution is only 15° (interpolation in between used in CATT-A/TUCT processing) but that may be compensated for that there are many sets to choose from. The sets are
measured both from femal and male subjects (indicates which), the female sets are: 1009, 1014-16, 1022, 1025, 1028-29, 1039, 1045-46, 1048-49, 1051-53, 1056.

After UnCTT the resulting ZIP is extracted to the "CATTDATA"\HRTFS folder.

HRTF and headphone eq format specs (v9: full license, v8:full Huron license)

Documentation (in Adobe's PDF-format) on how to create HRTFs and headphone eq filters from measured data. Note: if you are planning on meauring HRTFs and don't have the Huron license it can be issued without extra cost, the main purpose of the Huron license is that it will enable utilities that 99% of users that do not own Lake hardware will have limited use of.

    hrtfinfo_v7.CTT (28kB)

Note: the HRTF v7 format for can be used also with v8 and v9.
Note: from v8.0c HRTFs with arbitrary resolution can be used but the conversion cannot be done in CATT-A since each library will be unique, contact CATT for details.

Headphone filters (full license at any time)

A first set of headphones have been measured and filters for 44100 and 48000 Hz sample-rates have been processed. To use them, also the main application needs to be updated (v7.0b or higher). Each filter is 65kB in download size (long filters to control some of the LF properties).
Alphabetical order after brand
Headphone (* = recommended) Hz Hz Comment For HRTFs type
AKG K240 44100 48000 - plain
AKG K240df 44100 48000 - plain
*AKG K500 44100 48000 - plain
*Beyer DT531
*Beyer DT990 Pro 44100 48000 - plain
JVC HA-D626 44100 48000 old plain
Koss CD/4 44100 48000 lightweight, old plain
Koss portaPro 44100 48000 lightweight plain
Sennheiser HD414 Classic 44100 48000 - plain
*Sennheiser HD545 Ref. 44100 48000 - plain
*Sennheiser HD600 44100 48000 - plain
Sennheiser RS5
wireless FM
*Stax Lambda Pro 44100 48000 electrostatic plain

Be ware that no filter can perfectly compensate for a headphone since the transfer function may vary considerably:

  1. between headphones of the same type (due to manufacturing/wear)
  2. between different persons wearing the same headphone (different coupling to the head/ear)
  3. between replacements of the same headphone on the same person (different coupling to the head/ear)
The variation typically starts from 5 kHz and may be as large as +/-15 dB for the highest frequencies (some models are worse than others). Just like HRTFs, headphone eqs are ideally personal.

A headphone's suitability for binaural replay has very little to do with how suitable it is for normal stereo listening since the goals are completely different. For example, most stereo headphone designs attempt to suppress the ear canal resonance at 3-4 kHz with a -3 to -30 dB notch with various Q-values depending on brand/type, while for binaural listening, based on HRTFs measured with microphones at the entrance of the blocked ear canal, the headphone should ideally have a flat response (as measured at the same microphone point). The headphone filters attempts to create a reasonably flat response.

The HRTFs themselves also give a coloration unless they are from the person listening so it will anyway never be possible to do it perfectly. Fortunately the hearing is quite good at adapting to a coloration so it is possible to learn to interpret auralization also with some coloration. An example on how the ears adjusts to coloration is to listen to one pair of headphones for a while (any music such as from a CD) and then switch to another pair of headphones. Initially a big coloration difference will be perceived but after a while listening to the second pair they no longer sound so different. When listening to a binaural auralization it is also important to think "I am listening to a the natural acoustics in a room" and not try to compare it to listening to recorded music from CDs which is heavily processed, and stereo where you don't get any cross-talk between the ears..

If the filter for a new headphone is not found here, an similar one can often be used. This site:

can be used to compare headphones. Unfortunately the way they measure includes the ear canal so it isn't directly useful for eq but it can be used to compare eqs between models.

Note: the headphone eq format for v9 remains the same as for v8 and v7.

Anechoically recorded (or dry) music and speech

Material Description  yymmdd

Audio CD
CD B&O 101
Included with CATT-Acoustic full version.
Japan Audio Society
"Impact 2"
Out of print 1)
Many good instrument samples, originally recorded by Yamaha.

"Anechoic Orchestral Recordings"
Out of print 1)

Wenger Corporation
CD with anechoic choir music
See ASA/NOISECON 2005 paper.
Contact  Ron Freiheit at Wenger for more info.

"Test CD for Sound Reinforcement Systems"

Out of print 1) but some tracks may be available for download.
Not anechoic but very dry.

Many companies offer test CDs that may have some useful dry tracks.

Sound search sites 2)
Sound effects and musical instrument samples

International bank of sound documents (historical)

Misc. downloadable sounds

Misc. downloadable sounds


University of Ferrara
The Dipartimento di Ingegneria Università di Ferrara, Italy have made available a set of anechoic recordings of islamic songs, byzantine songs from the
CAHRISMA project and a set of anechoic ancient greek songs and music from the ERATO project.
Non-commercial use only.
Helsinki University of Technology A project that offers recorded symphony orchestra musicians one by one in an anechoic chamber (instruments on individual tracks). 090110
University of Iowa
Short intstrument samples. Note: this link seems to
have changed and a search didn't find it (071124)
University of Salford, UK
A fun and informative site with an anechoically recorded duck (!)
General Many acoustics departments at universities have anechoic chambers and may have recorded useful material.
Many collections of sampled instruments used for MIDI synths are near anechoic but it can vary a lot between collections.

Files for download

"as is"
Brass Quartet
4 x mono
(29.5 MB)
Members of the WPI Brass Quartet (separatelly) recorded by Dick Campbell using bell clip-on microphones in semi-anechoic conditions. The players were spaced about 3m apart and better than 30dB isolation was achieved. Best used
for multiple source auralization.

Sampled organ
(1.27 MB)
A quite realistic-sounding sampled organ. Note that organs are big so auralizating them in a good way is very hard. On the other hand a long reverb masks details so it depends.

Grand piano
(10.8 MB)
A closed-mic recording inside, lid up, of a freshly-tuned Yamaha Concert Grand. Note that also
a piano is hard to auralize due to size and complex radiation patterns.

1) It may be possible to find a second-hand copy e.g. on Amazon. Note that even if a CD is out of print the copyright still holds so downloading a ripped copy means violating the copyright.
All sorts of sounds, some are more or less anechoic or at least dry.

File converters (all licenses at any time)

Note: from v8.0e, if put in the CATT folder these converters can after a restart be loaded via File|External CATT Tool.

See also 3rd party utilties

DXF converter

A DXF converter is included in all version from v8.0e:3, see File|External CATT Tool

EASE v3 (and v4) geometry export to CATT GEO/LOC-file converter

A converter is available from EASE v3 geometry export formats (.XAR/.XFD/.XLD/.XST) to CATT (.GEO/.LOC).

  EAS2GEO_EXE.CTT  (020228, 46 kB)
EAS2GEO_HLP.CTT   (020228, 16 kB)

However, there are some important differences in how the geometry is built and that must be considered (also documented in the included helpfile):

  1. audience areas are in EASE modeled as floating single-sided planes above the audience and the audience itself is modeled on the floor. These audience planes have no consistent normal direction, but the importer forces it to be upwards. The planes must be converted to a boxed-in audience after import, modeling the audience on the floor will not give good results and floating audience planes should not be used. For reference, the floating audience planes are converted to a separate included GEO-file that can be switched off or modified.
  2. sub-divided surfaces, say a window in a wall, apparently called "coated surfaces" in EASE, are in EASE modeled by placing the window surface some mm in front of the wall and must be put back into the wall (e.g. using lock()) and converted to sub-divisions after import.
  3. double-sided planes like reflectors are only exported as a single plane and the other side with opposite normal has to be created after import.
  4. 1-3 will show up as single-connected corners in the debug file
  5. models seen so far have been quite inaccurate but it is not yet clear if that has been modeling errors or inherent EASE problems. The export uses an inconsistent number of decimals (from 1 to 6 without apparent logic) so some of the inaccuracy may come from the export itself. It is strongly recommended to create a geometry debug file after import, checking plane normals also seem to be a good idea.
  6. keep in mind that if you are involved in a project where EASE have been used, and you want to import the model to save some modeling time, that many times the EASE model has been created only to check the sound system and the direct sound coverage and it may not be very well suited for room acoustics prediction.
EASE v4 room files can be imported with some minor changes, please send any v4 files to CATT so that any v4 changes can be implemented. If you wish to try the conversion of v4 files yourself, simply change the "Format" line to say 3.0 instead of  4.0. It seems that the format tag doesn't actually indicate a format change but instead just indicates the version of EASE that created the file. At least, so far all  all v4 files seem to have converted well making them appear as if exported from v3.

EASE v2 loudspeaker export-file (.EXP) to CATT-SD1 import text-file converter

In all cases it is better to ask for CLF files first but if not avilable EASE v2 data may be.

  EXP2SD1_EXE.CTT (071018, 54 kB, this version also works with the Xtra32.DAT license file used from CATT-Acoustic v8.0g)

EXP2SD1 converts to the CATT-SD1 text import format (v7 or v8).  If a user succesfully has converted models in an EXP-file to CATT format they can be sent to CATT and will be provided "as is" to other users.

Odeon file converter

Odeon 3.x and 2.x surface file (.SUR) and material library (.LIB/.LI8) converter (32-bit Windows application). This is an official program since the conversion is based on an interchange of information between CATT and Odeon A/S. Later Odeon versions can read the CATT-A .CAD export format and can also export in CATT format.. Data can thus be moved both ways between Odeon and CATT-A but care must be taken regarding how geometry and scattering coefficients and semi-transparency are handled in the two software.

  Ode2Geo_EXE.CTT (39kB)
Ode2Geo_HLP.CTT (23kB)

Note: these have not yet been converted to work with the Xtra32.DAT license file used from CATT-Acoustic v8.0g or later. It can be fixed if needed but the old Odeon format is of little interst now. Later version of Odeon can export to GEO format (some work remains after conversion but in principle it works).

Epidaure file converter

A first beta version of Epi2Geo has been completed (030807). This is a converter from the room model GEO format used by the French prediction software Epidaure to CATT-Acoustic GEO.
Please e-mail any Epidaure GEO- and corresponding material library MAT-files you may have so that  the converter can be further tested before release.

3rd party utilities

Common to all 3rd party utilities is that support (if any) is given by the authors and not by CATT.

SketchUp plugins for conversion to CATT GEO:
MATLAB(R) utilities

Tips and tricks

T1. Studying reflector coverage
T2. Mapping only the direct sound

T1. Studying reflector coverage

v7: To see how one or more reclectors cover the audience, in General settings only those planes that are intersting can be switched on (Plane use/Only some). Typically, these planes would be the reflectors concerned and the audience but sometimes also the walls may be ineteresting. Then do a high density Audience area mapping and look at the SPL in time-windows (possibly set to shorter windows than the default, say 0..20, 20..40, 40..60 and 60..80). Since the model is now open even lots of rays will be very fast since most rays escape very quickly. Remember that due to diffraction small reflectors will give only high freqency coverage but to some extent this can be handled by the use of auto-edge diffusion.

v8,v9: use the new Geometry view/check REFLINFO.PLT /.PL9 where reflector edge contours are shown without any calculation required.

T2. Mapping only the direct sound

v7: To map only the direct sound in Audience area mapping, switch off all parameter calculations and switch on Direct only in the mapping in time-intervals group. If no parameters need to be calculated no actual ray-tracing is performed and the number of rays selected does not matter, since direct sound is not calculate by rays. Mapping only the direct sound can then be very fast since no rays are traced .

v8.0a-d: has a short-cut button that selects direct-sound only functions. Use also the new Geometry view/check SRCINFO3D.PLT where -3 dB directivity contours are shown without any calculation required.

>= v8.0e and TUCT: have separate direct sound mapping.

Frequently Asked Questions

Q1. Why does the reverberation time become longer than the one estimated by Sabine and Eyring (SabT, EyrT)?

Q2. Why do calculations sometimes indicate a big loss of rays?

Q3. How can I estimate the values of scattering coefficientsa (v7 diffusion factors)?

Q4. Why does the <= v7.1 convolver sometimes fail to read a WAV-file that I have created myself (full versions)?

Q5. Why can't I always select samplerate in the Crosstalk cancelling dialog (full versions)?

Q6. How can I do e.g. an STI color map over standing listeners like in a train station?

Q7. Why is it difficult to achieve a good RT match for very hard rooms using "normal" absorption coefficients?

Q8. How can models with deliberate holes be handled?

Q9. Can I place a source (or a receiver) directly inside a wall (or an audience surface)?

Q10. Can I model the audience as a floating plane without sides?

Q11. Why is the geometrical volume calculation sometimes inconsistent?

Q12. Will the CATT AutoLISP interface work with AutoCAD 2000 or higher?

Q13. Which are the possible reasons for ray loss

Q14. What is the directivitiy of a human talker

Q15. How does surface (default and actual) and edge diffusion relate to each other?

Q16. Can I let clients view PLT-,PL9- or OGL-files using the stand-alone viewers? What files are required?

Q17. Do I need to calibrate WAV (or SIM) files before WAV (or SIM) file addition? (v8)

Q18. How can I calibrate WAV-files that are created from separate WAV-file additions? (v8)

Q19. Can CATT-Acoustic handle coupled rooms?

Q1. Why does the reverberation time become longer than the one estimated by Sabine and Eyring (SabT, EyrT)?

  1. No scattering coefficients have been applied or diffuse reflection is switched off (General settings). If a hall does not act as "geometrically mixing" due to its shape and if the absorption distribution is uneven, the RT is very dependent on the settings for diffuse reflection. In general no surface should have less than 10-20% diffusion (use Default diffusion in General settings) and surfaces that have some roughness higher values (see Q3 below). For reflectors automatic Edge diffusion can be used. Note that Sabine and Eyring values actually assume that all surfaces are 100% diffusing and that all surfaces are visible from any surface. A useful paper can be found here:
  2. The geometry may have been modeled so that the volume (V) and/or the surface area (S) is not correctly estimated and V and S affects the Sabine and Eyring values (see v8 manual 2. Prediction module/Modeling notes or v9 manual 2. Modeling module/Modeling notes). In such cases the two estimates of average absorption factor (AbsF and AbsFg seen e.g. in the right graph in RT_ss.PLT) will often differ significantly.
  3. If, with reasonable scattering coefficient values and accurate absorption data, the RT still is longer than Sabine/Eyring the room is highly likely to give a double-sloped decay also in reality. A good "engineering check" is to calculate both with and without diffusion to see how much the RT differs. If it does not differ a lot the room behaves nicely statistically and the predictions will be more accurate.
Q2. Why does calculations sometimes indicate a big loss of rays?

There are several possible causes to lost rays, some are ntaural and some are the results of modeling mistakes.

  1. The source may have been placed directly in (or even outside a wall) making half (or all) of the rays escape.
  2. The model has holes (use PLINFO.PLT/-PL9 or COLORED.PLT/.PL9 geometry plots to check, don't forget to view the model from below). Even fairly small holes can cause a lot of rays to eventually escape.
  3. The model has reversed planes (use PLINFO.PLT/.PL9 or COLORED.PLT/.PL9 or the OpenGL 3D-viewer geometry plots to check).
  4. Some planes are very inaccuratelly modeled (i.e. some corners are far out of the plane as described by a plane equation calculated from three of it scorners). The debug file will list such planes (Geometry view/check).
  5. If the predefined artificial absorption TOTABS has been used a lot, rays will not be lost but rather absorbed and it may lead to an open room conditions since vert few rays will remain bouncing around. Use rather a <99 99 99 99 99 99> absorption (or more physically correct lower at low frequencies) than TOTABS. "Black and white modeling" i.e. either totally reflective or absorbing surfaces may be useful sometimes to exaggerate problems and tendencies in a room shape but it does not sit well with getting good results and absolutelly not for auralization.
  6. See Q8 for more details on how indended holes can be handled
Q3. How can I estimate the values of scattering coefficients (v7 diffusion factors)?

AES and ISO have had working-groups on the subject for many years aiming to measure scattering coefficients and diffusion factors. It is a complex subject but some useful data for computer modeling is now coming out of it. Two types of coefficients have been defined:

Diffusion coefficient (d): is a measure of the uniformity of the scattered sound. The purpose of this coefficient is to enable comparisons between diffusers at the design stage. For a detailed definition and measurement procedure see the standard document (AES-4id-2001, JAES 49(3), 149-165, 2001). This coefficient is not to be used in CATT-Acoustic (even if this is the name used in v7 that preceded the ISO/AES work).

Scattering coefficient (s): is a measure of the total amount of scattered sound - for random incidence - in relation to specular sound. The purpose of this coefficient is for use within CP software such as discussed in these papers. Fore a detailed definition and measurement procedure see (ISO/CD 17497:2000, "Acoustics - Measurement of the random-incidence scattering coefficient of surfaces"). This coefficient can be used in CATT-Acoustic.

For an overview of both coefficients and how they relate to eachother see:

This definition of coefficients is recent and CATT-Acoustic has during the initial 8 years it handled diffuse reflection used the general terms "diffusion factor" and "diffusion coefficient". From v8 the new terminology is used i.e. scattering coefficient (s).

However, for most walls and objects no measured data will be found and the guidelines below can be used:

If in doubt, try with both high and low values and see if the results are sensitive or not (it depends on the hall shape and the absorption distribution and is very difficult to know in advance).

If an existing room case is going to be "tuned" for prediction e.g. with a new PA system, the following procedure is recommended:
  1. estimate the existing absorption as well as possible, avoid TOTABS, use 99% instead.
  2. set the scattering of any audience areas like above.
  3. use autoedge on all small objects with free edges or where there is impedance mismatches.
  4. assign surface diffusion as above on actually uneven/rough surfaces
  5. fintetune the remaining overall surface diffusion, starting from the recommended values above, to match the measured T-30 . In most rooms, if all the other steps are done this should typically not need much adjustment.
  6. if the predicted T-30 still differs significantly from the measured T-30 it is likely that a) something significant has been missed, b) the measurement is not good (low frequency noise problems are common)  or c) that the room has estimation problems due to extreme shape and /or absorption distribution. Please send the files for feedback in cases like that, see Support.
Note: v8.0c build 6 introduces a way to automatically estimate the scattering coefficient for a certain roughness scale:

   ABS diff = <15 10 11 12 12 12> L < estimate(0.1) >

where the estimate() argument is the roughness scale in meter..

Note: do not use coeffcients found in articles where the software concerned is not based on the Lambert distribution, for discussion on various scattering distributions see B-I Dalenbäck, "Scattering distributions in geometrical acoustics"
Forum Acusticum, Aalborg, 2011.

Also see papers listed on the main CATT page Papers section that can be downloaded.

Q4. Why does the <= v7.1 convolver sometimes fail to read a WAV-file that I have created myself (full versions)?

Removed, concerned only v7.

Q5. Why can't I always select samplerate in the Crosstalk cancelling dialog (full versions)?

If Normal operation is selected then the samplerate is determined by the SIM-files to be filtered. It is only when Create X-talk filter only is selected that the samplerate can be set (should then correspond to the binaural WAV-files to be filtered, typically 44100 Hz).

Q6. How can I do e.g. an STI color map over standing listeners like in a train station?

This is an example of a situation that cannot be simulated as straight forward as a seated audience but it can be done in a quite satisfactory manner using the steps below.

  1. First select the floor as "audience plane".
  3. Set a map at ear height (1.7 m or so), ignore the warning that map height should be = half a map step since it applies only to a seated audience (so that rays cannot travel under the receivers without being detected).
  5. Assume that the absorption area (in m2 Sabine) of a standing person is Ap, that there are Np persons on the floor, that the empty floor absorption is alpha_empty and that  the floor area is Sf.
  7. Calculate a new floor absorption "with people" like this: alpha_new = (alpha_empty*Sf + Np*Ap)/Sf.
  9. Increase the diffusion of the floor to indicate that it is occupied by people scattering the sound.
  11. For some refinement the area below each person could be removed making a slightly different formula but it is likelly not to be necessary since the floor is typically very hard in cases like this and the absorption from the people will dominate.
Q7. Why is it difficult to achieve a good RT match for very hard rooms using "normal" absorption coefficients?

Normally, for rooms such as auditoria with just a few hard surfaces ABS concrete = <1 2 2 3 3 4> or similar works fine (values depend on if the concrete is painted or not etc.). To change to <2 4 4 6 6 8> will not change the RT dramatically since the concrete absorption still is small as compared to the audience absorption. However for a very hard room, such as an empty reverberation chamber or a totally untreated room with concrete surfaces, making the change above will half the RT since it is directly dependent on the values for concrete and decimals in the absorption percentage starts to count! This has nothing to do with the prediction method used but is just how it works. There may be other similar cases where e.g. a church may be built mostly of brick walls and the values for brick will directly control the RT for the empty case (and brick is one of the worst materials to know the absorption for since it depends on the stone porosity, the mortar and if the mortar is flush with the stone or not etc.).

Q8. How can models with deliberate holes be handled?

Deliberate holes in a model (e.g. an open side in a train-station or an open window) can be handled in several ways depending on the situation.

CATT-Acoustic v8.0 Full detailed:

  1. To have an actual hole (by not modeling surfaces at all or by switching planes off in General settings): recommended when the holes are a big fraction of the total area; this will indicate a number of rays lost. A lot of rays should be used in this case (calculations are faster with an open case then with a close case).
  2. To model the holes by surfaces with the pre-defined absorption TOTABS, an alternative if the open area is relativelly small; this will not indicate lost rays but rather absorbed rays and will not issue a warning. This option will allow Interactive RT estimate calculation (a Sabine RT is reasonable if the openings are small).
  3. To model the holes by surfaces with very high absorption <99 99 99 99 99 99>, an alternative if the open area is small; the advantage is that more rays will remain bouncing around giving better statistics as compared to 2) and will also allow Interactive RT Estimate.
TUCT Predict SxRModel the case as is with holes and openings and use algorithm 2 or 3.

Audience area mapping: for both CATT-Acoustic v8.0 and TUCT model the case as is with holes and openings but use more rays and Adapt rays off.

Q9. Can I place a source (or a receiver) directly inside a wall (or an audience surface)?

No, typically not. If a source is placed exactly in a wall about half of the rays will directly escape towards outer space indicating a big loss of rays. If a receiver is placed directly inside an audience surface about half the rays will go undetected (even the direct sound) since it will depend on the least bit of accuracy that will flip between 0 and 1.

Q10. Can I model the audience as a floating plane without sides?

No, normally not since it will only give a correct estimate for direct sound and first order reflections. Always model the audience as a box with sides (at about 1.2 m height and place the receivers slightly above - at ear height). A floating plane audience is sufficient only for direct sound mapping but reverberation time and most parameteres relying on the late part will be wrong. See manual page 2-39 for details (Fig. 2.8) or the corresponding help-file section. Unfortunatelly, the tutorial for v7.0 and earlier manuals show a floating audience to make it simpler and not everyone notices the comment that a box should be made for any real rooms. v7.2 and v8, v9 manuals show an audience box.

Q11. Why is the geometrical volume calculation sometimes inconsistent?

Removed, concerned only v7.

Q12. Will the CATT AutoLISP interface work with AutoCAD 2000 or higher?

Yes, from what has been seen so far it will. One thing that has been discovered is if a CAD-file (exported from CATT-Acoustic)  is imported via the interface, and the AutoCAD flags OSNAP and OTRACK are on, the imported drawing has errors. If this happens, set these flags off while importing and then back on again as required.

Q13. Which are the possible reasons for ray loss?
Assuming the model is supposed to be closed these are these likely reasons:

  1. There are big plane inaccuracies (warped planes).

  2. It is a good practise to generate a debug text-file every now and then (Geometry view/check) and check so that there are no significant INACCURATE PLANE CORNERS. If there are they should be fixed and using the lock()
    function is often the best solution if planes are not purely in x-y, y-z or x-z, see v7.2 manual page 2-33 (v8 2-38).
  3. Some plane ids may have been used more than once (by mistake in OFFSETPL, MIRROR and/or object COPY directives).

  4. Also this is given in the debug file (DUPLICATE PLANE  IDs) but immediate debug will trap it directly. This must absolutelly be corrected.
  5. The source is placed exactly inside a wall, see also Q9.
Q14. What is the directivity of a human talker?
Although is is possible to find estimates of the directivity it may not be wise to apply it. The reason is that a talker always turns his head (may even look backwards to a blackboard or a viewgraph screen). It is therefore more useful not to use the exact directivity but one with a bit lower DI corresponding to some average head-directions than to use it as if the head was fixed.

Q15. How does surface (default and actual) and edge diffusion relate to each other?
Assume that you have defined two abs materials in a GEO-file or in the Surface properties module as:

ABS nodiff = <...>
ABS diff   = <...> L <...>

Some abbreviations:
Default, Diffuse reflection option in General settings
Surface, Diffuse reflection option in General settings
S+E Surface+Edge, Diffuse reflection option in General settings
surface default diffusion values as selected in General settings
edge diffusion (calculated based on surface size)
surface diffusion (as in diff above)

Resulting diffusion for various setting combinations in General settings
Plane definition
S on, D off
S+E on, D off
S on, D on
S+E on, D on
[ ... / ... / nodiff  ]
[ ... / ... / nodiff* ]