Handbook for Sound Engineers

Computer Aided Sound System Design 1379

• Predicted sound pressure level, viewed at octave or

octave band frequencies, and at an average of

these frequencies, Figs. 35-53A to C.

• Predicted intelligibility values (in the 2 kHz octave
  band, or the weighted average of 500 Hz to 4 kHz
  octave band data), listed in STI or RASTI values,
  Figs. 35-54A and B.


• Predicted acoustic measures (for octave or octave
  band frequencies), listed in C80, C50, %Alcons,
  center time, strength, or other values according to
  ISO Standard 3382 (compare Fig. 35-55A and B).

35.4 Verification of the Simulation Results

After the simulation, the practical design, and the instal-

lation, it is important to check the results and to com-

pare them with the prediction. For this purpose tools we

developed during the last 20 years:

• The most famous TEF 10, 12, and 20 by Crown (later
  Gold Line).


• MLSSA by DRA Laboratories.


• SMAART by SIA Soft.


• WinMLS by Morset Sound Development.


• DIRAC by Brüel & Kjær.


• SpectraLAB by Sound Technology Inc.


• EASERA by AFMG Berlin.


• EASERA SysTune by AFMG Berlin.

All measurements with predefined excitation signals

generally utilize two or more ports. The input port of the

system under test (DUT) is fed with an excitation

signal, generated by the analyzer. Fig. 35-56 shows the

block-diagram for a modern software-based four-port

measurement tool including the needed AD/DA

converter.

Figure 35-51. Echo detection in EASE 4.2.

A. Initial time delay gap (ITD) mapping.

B. Echogram in weighted integration mode.

C. Echo detection curve for speech.

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Figure 35-52. Frequency response of loudspeaker cluster.
A. Non-aligned cluster.
B. Aligned cluster.