Handbook for Sound Engineers

1340 Chapter 35

Since 1970. The programmable pocket computer
offered the first algorithms for acoustics.
1980–1985

Since 1981. The PC and PC-XT have been available.

1984: Reverberation time and intelligibility calcula-
tions for simple rooms:
CADP / JBL.
TEF-10-Analyzer. First coverage plots became reality.

1985: PHD Program. By Prohs/Harris in spring: first
version for TEF Analyzer:

1. Room-acoustic calculations like different reverber-
   ation times.


2. Loudspeaker cluster design.


3. Power calculation for horn radiators and corre-
   sponding drivers.


4. Alcons calculations by Peutz.

1986: BOSE-Modeler. First full-graphic CAD Macin-
tosh-based program, Version 1, 1986, by K. Jacob, T.
Birkle/Bose/United States.

1987: Acousta-CADD. First full-graphic CAD MS-
DOS-based program, Version 1, by A. Muchimaru,
Altec Lansing/United States.

1990: EASE. Full-graphic CAD MS-DOS-based
program with pop-up menus, Version 1, 1990, by ADA,
Germany.

1991: CADP2. Full-graphic CAD Windows 3.1-based
program, by JBL/United States.

1996: ULYSSES. By IFB/Germany (P. Hallstein).

1997: CADP2. Further development stopped.

1999/2001: EASE for Windows. By Ahnert Feistel
Media Group.

Room Acoustics Programs

1988: CATT-Acoustic. Dalenbäck/Sweden, Version 1,
now Version 8.0.

1991: ODEON. Naylor & Rindel/Denmark, Version 1,
now Version 9.0.

1994: RAMSETE. Farina/Italy, Version 1, now Version
2.5.

1998: CAESAR. Vorländer/Schmitz/Aachen/Germany,
Version 0.12, 2001 Version 0.20.

2002: AURA. (Room acoustic module) in EASE
Version 4.2, now Version 2.2.

The programs printed in italics are subject to

constant advancement.

35.1.1 Measurement and Planning Methodology

with Physical Models of Large Auditoriums

by Hans-Peter Tennhardt

35.1.1.1 Fundamentals

The room impulse response is obtained in a reduced

model of the auditorium interior by applying the corre-

sponding scale-model laws based on the constant ratio

between the geometrical dimensions L of the room and

of the sound wavelength O in the model scale (index M)

and in natural scale (index N):

(35-1)

where,

c is the speed of sound,

f is the frequency.

If the scale-model test is carried out in the same

sound propagation medium, then and so Eq.

35-1 becomes

(35-2)

i.e., the measurements are carried out in a frequency

range that exceeds the original frequency range by the

factor p (reduction scale 1:p).

A favorable compromise regarding model size and

accuracy of reproduction is given with a reduction scale

of 1:20, but scales between 1:8 and 1:50 are feasible

depending on model size or frequency range to be

studied. The sound impulse is irradiated from the loca-

tion of the sound source (e.g., stage, orchestra pit, loud-

speaker). The acoustical response of the room to the

emitted signal is simultaneously registered at receiving

positions (audience area, platform, stage) by special

electroacoustic transducers (microphone, dummy head

L

O

---=Const

LNufN

cN

=-----------------

LMufM

cM

-------------------=

cN=cM

p

LN

LM

------ -=

fM

fN

= -----