CATT-Acoustic v8.0

Prediction Module

The hall geometry is described using a structured hierarchic text format manually created, via AutoCAD or other CAD plugins:

INCLUDE statements enables a hierarchical structure with hall parts defined in separate files
expressions/math functions (e.g. sin(), cos())
local and global symbolic numerical constants (e.g. GLOBAL ceil_height = stage_height + 10)
symbolic string constants (e.g. LOCAL wup = "wall of unknown plaster") e.g. shortcut names
interactive input of constants with limit check (e.g. GETLOCAL h = 8 INFO = "Ceiling height in meter" MIN = 5 MAX = 18)
tracing and break statements (SAY, RETURN, BREAK, DEBUG, DEBUGON, DEBUGOFF)
if-then-else statements for geometry variants
IF balcony THEN
... balcony planes
ELSE (optional)
... other planes
ENDIF
comments
tools for surface corner locking and object rotation, translation and copying etc. (e.g. lock(), cut(), x(), y(), z(), OBJECT, ROTATE, TRANSLATE, COPY)
mirroring of symmetrical (or nearly symmetrical) models (MIRROR)
optional hiding of invisible edges
one-step generation of circular coordinates and similar using the loop() function ( e.g. loop(500,a,0,315,45,2*cos(a),2*sin(a),3) )
plane loops to create e.g. circular shapes with one command
double-sided planes with one command
one-step generation of receivers coordinates using the recloop() functions (possible OVERRIDE of loop-created positions)
enables very accurate, consistent and maintainable models
frequency dependent semi-transparent surfaces (e.g. hanging curtains)
export of geometry to AutoCAD interface, DXF, VRML, CATT Marker 3D object format (for GEO objects and source visuals), CLF cabinet format (useful for CLF authors).
import of geometry via AutoCAD interface or DXF (DXF converter available also in demo)
merging of planes e.g. after an AutoCAD interface export or DXF with 3DFACEs
import of geometry via SketchUp plugins (3rd party: Skp2Geo by Euphonia, France, SU²CATT by Rahe-Kraft GbR, Germany and MCTS by Duran Audio France)

simple shoebox GEO-files/graphics

an AutoCAD interface written in AutoLISP is included that creates files in the CATT format directly (models created in the CATT format can also be exported to AutoCAD via the interface using an intermediate file format)
Export to the CATT 3D-viewer based on OpenGL including source directivity -3, -6 and -9 dB contours. Interactive source aim and positioning, surface data and selection.
Optional non-acoustical element "markers". Markers can be in the forms of lines, polygons, circles, discs, rulers, 3D text and loaded objects (e.g. chairs, etc.).

simple marker graphics

General utilities requiring no calculation:

	source directivity contours
	reflection coverage

VRML 2.0 export. The Virtual Reality Modeling Language enables interactive 3D models - with auralized sound (click a 3D button and the binaural sound associated with the view is played). VRML-files (.wrl) can be linked to web pages by using a VRML Browser plug-in or add-on to WWW browsers. v8 is (at a minimum) compatible with Cosmo Software's VRML-browser CosmoPlayer v2.1 and Platinum Technologies' VRCreator 2.0 (so that individual surfaces can be colored or mapped e.g. wood textures to and ehanced in various ways for presentation). Note: As from Feb 1999 VRCreator is no longer supported by Platinum and new software will be available, news was to appear on May 31, 1999.

	sample VRML scene, as exported, screen shots, *no VRML-plugin required*
	sample VRML scene, as exported, VRML-plugin required

If you have no VRML plugin get one at the VRML Repository. After the page has loaded, switch off "Gravity" and "Collision detection". Each receiver and the source have their own Viewpoints. So far no sound has been added to this example.

VRML can also be imported into many 3D graphics software such as 3D Studio.

Interactive RT estimate calculation:

Included is a very powerful and easy to use spreadsheet-like function where Sabine and Eyring RT estimates can be done while changing absorption. In addition a global ray-tracing can be performed that contiously updates the RT-curve. For some halls (due to a "mixing" shape or suitable diffusion and absorption distribution) the Sabine and Eyring RT estimates come very close to actual T-30 values estimated from line regression on the decay curves. For such halls, what if? RT calculation games can quite safely be based on classical RT estimates. In addition to Undo and Revert options, the surface list can be sorted according to various criteria to aid in understanding which surfaces control the RT most:

absorption (125&250, 500&1k, 2k&4k or 125-4k Hz)

absorption Area (125&250, 500&1k, 2k&4k or 125-4k Hz)

plane (Id, Name or Area)

absorption use statistics (how much of each material is used etc.).

Sabine, Eyring

mean absoption coefficient

mean free path

volume and surface area

Schröder frequency

geometrical acoustics limit estimate

utilizes multi-core CPUs (a complex model will be twice as fast on a dual-core CPU and four times faster on a quad-core)

Sample RT-calculation dialogs

Note: the information below concerns the current CATT-Acoustic™ for the new CATT TUCT™ see overview.

Prediction is based on the unique RTC-II (Randomized Tail-corrected Cone-tracing, second version), Ray-tracing, or the ISM (Image Source Model) :

up to 260 sound sources

up to 100 receivers

frequency dependent diffusion

optional automatic surface size and frequency dependent edge diffusion

frequency dependent transmission (semi-transparency e.g. hanging curtains)

frequency range 125 Hz to 16k Hz octave-bands (extrapolation is made if 8k and 16k values are not avilable to enable full frequency range auralization)

The RTC is used for full detailed prediction:

the RTC is a very general prediction method and is the result of 9 years of development and experience from the ISM, Ray-tracing and Cone-tracing and could be called the mother of all hybrids since it uses elements from all three methods

auto features that suggest a sufficient number of cones and cone truncation time

optional alternative late part algorithm that better predicts coupled or otherwise special rooms

animated rays and echograms

full-length echograms

detailed early part echograms

directional early part echograms (X, Y, Z)

optional curves displayed on echograms to help identify potentially detrimental early reflections in e.g. cinemas (based on a Floyd Toole AES paper)

calculation of measures: D-50/C-50, C-80, Ts, LF, LFC, G, SPL, RASTI, STI (several version including IEC 60286-16), EDT, T-15 or T-20, T-30, Sabine RT, Eyring RT, Direct To Reverberant Ratio

optional calculation of U50 (C50 with background noise taken into account accoring to J S Bradley), AI (Articulation Index), PI (Speech Privacy Index), SII (Speech Intelligibility Index, only implemented for weak reverb cases)

optional individual receiver background noise

Stage support parameters (STearly, STlate, STtotal)

octave-band Transmission Index curves

selectable echogram smoothing with filter type and time constant selectable for each octave-band

ray incidence "sound roses" in six different selectable time intervals

vectorgrams that show both the echogram and ray incidence angels in a single 3D plot

spectra plots for direct, 0..50 ms and total SPL to aid in deciding overall eq and system design

EKgrad (echo-disturbance graphs according to Dietsch & Kraak), speech, music or speech+music

wall hit statistics

mean free path statistics

mean absorption statistics

average RT graphs and other statistical data

spreadsheet export

optionally includes interference effects between direct sounds from multiple sources (post-processing in the Source addition module)

ray leak display and leak occurance as a function of time (for judging leak severity)

optinonal MATLAB output of all results (useful with the MATLAB interface in the Sequence processing module)

utilizes multi-core CPUs (a complex model can be twice as fast on a dual-core CPU and four times faster on a quad-core).

sample RTC graphics/screen-shots

Ray-Tracing is used for audience area 2D/3D color mapping:

Note: the information below concerns the current CATT-Acoustic™ for the new CATT TUCT™ see overview.

separate mapping of direct sound and direct+reflected sound

auto features that suggest a sufficient number of rays and ray truncation time

optional 2-20x speed-up with near identical results

optional source ray factors to allow more rays to more important main sources and less to e.g. fill sources

mapping of direct sound with optional -3, -6 or -9 dB contours

mapping of closest source groups including delays

mapping of early coverage: SPL and LF in four time intervals (e.g. 0-20, 20-50, 50-80 and 80-300 ms)

mapping of measures: D-50/C-50, C-80, Ts, LF, G, SPL, RT, RASTI, STI (several version including IEC 60286-16), + source-group delays and closest source-group

optional prediction of a noise map to use as background noise for STI and RASTI

mapping statistics (e.g. "33% of all C-80 values are between -2 .. 2 dB" ), quick text-style bar-graps and spreadsheet export.

optionally includes interference effects between direct sounds

animated rays and maps

3D rotatable maps

maps can optionally be smoothed

utilizes multi-core CPUs (a complex model can be twice as fast on a dual-core CPU and four times faster on a quad-core)

sample mapping graphics/screen-shots

Pixel rendering of direct and reflected sound:

Note: the information below concerns the current CATT-Acoustic™ for the new CATT TUCT™ see overview.

optionally includes interference effects between direct sounds, with a quick render option

maps model surfaces, only fictive audience areas (as from mapping), or both.

direct and reflected sound pixel rendering graphics

"Time trace" wavefront-like display:

Note: the information below concerns the current CATT-Acoustic™ for the new CATT TUCT™ see overview.

shows rays one time step at the time as they emerge from each source

creates plot-files where each time step is an animation frame so that time can be played forward as well as backward as a movie

color-codes ray segments according to SPL including directivity or reflection order

a qualitatively useful display for:

room shape analysis

reflector coverage

detrimental reflections like back wall reflections and focusing

sound system source delay analysis

useful for teaching basic ray-tracing concepts

time trace example

The ISM is used for qualitative early reflection analysis:

Note: the information below concerns the current CATT-Acoustic™ for the new CATT TUCT™ see overview.

detailed early echograms

image source 3D space

reflection trace (individual path interactive or all reflection paths)

sample ISM graphics/screen-shots

1995 prediction round-robin results:

methods employed in a previous version of CATT-Acoustic (v5) were very successful in a round-robin with 16 participants (Vorländer, Proc. 15th ICA Trondheim 1995)

CATT-Acoustic was one of only three programs that were judged to give reliable and useful results. Of these three 5 of the 8 predicted measures were best evaluated by CATT-Acoustic

The RTC utilized by v7/v8 gives overall better results being of a more general nature

The new CATT TUCT™ follows adds to the capablities and replaces the RTC see overview.

CATT-Acoustic 1995 round-robin model