Pro Sound Testing, Inc. is owned and operated by Pat and Brenda Brown. It is the sister company to Synergetic Audio Concepts, Inc., or SynAudCon. SynAudCon is a pro audio training company that provides in-person training worldwide, as well as web-based training courses. Visit our site at


Some History

Pat has been involved in high resolution measurement work since the 1980's, his first "real" analysis system being the Techron TEF12 Plus. It cost over $10,000 (1986 dollars!) but it changed his career path, enabling him to perform high resolution time domain measurements of loudspeakers and rooms. His first major design/build project was the Pepsi Coliseum at the Indiana State Fairgrounds, where he collaborated with audio legend Don Davis in the design and commissioning of the system.


He taught "TEF school" for Crown International in the 1990's. He was also one of the early adopters of the Bose Modeler room modeling program, and has been a user of the EASE room modeling platform since the DOS days. He became an avid user of CATT-Acoustic in the early 2000's, which continues to be his primary room and array modeling platform. He is co-author of Sound System Engineering - 4th Edition, and a contributing author to the Handbook for Sound Engineers - 4th Edition.


Starting a Measurement Lab

It became apparent at the turn of the century that the need had developed for an independent measurement lab to produce loudspeaker data files for room modeling programs. After failed attempts to get someone interested in the project, he decided to just do it himself, since it would compliment SynAudCon's training programs. He remodeled his shop building to add a hemi-anechoic room, built a loudspeaker rotating system (now 3rd generation), and acquired the necessary software measurement tools. After a year of contruction and tweaks, he produced his first balloon measurements (late 2005).


He has been an avid user of the Monkey Forest measurement  platform since that time - a powerful, DOS-based, industrial platform that remains the most powerful platform for loudspeaker measurements and data generation to this day. The software has been customized by MF author Swen Muller, and is now on version 39 and holding.


So, the Electro-acoustic Testing Company, Inc., or "ETC, Inc." was born. The company name was changed to Pro Sound Testing, Inc. in early 2015.


Loudspeaker Data Formats

In 2005, there were a number of data formats used by room modeling programs. Each was proprietary, and there was no way to use data produced for one program in a different one. He turned his attention to developing a common data format that could be used in any modeling program, largely because he did not want to produce multiple data file formats for the same loudspeaker. After investigating, he found that this had essentially already been done by the developer of CATT-Acoustic, Bengt-Inge Dalenback. Much of the format details and programming were already in place, but ongoing development had languished. The initiative was jump-started and eventually became the Common Loudspeaker Format or CLF, which has grown to become the most widely supported loudspeaker data format in the world. The CLF website provides an overview of the format.


So, Pro Sound Testing, Inc. produces loudspeaker data files in two formats - CLF and GLL. GLL is a proprietary format used by the EASE room modeling program. The other major modeling programs use CLF data files.


The Next Project - Power Amplifier Specifications

Audio power amplifier specifications are in as much disarray as loudspeaker specifications, so in 2012 Pat started the Common Amplifier Format initiative. The CAF establishes a meaningful set of specifications and a testing methodology to assist the sound system designer in deploying power amps. A complete description of the format can be found on the CAF website.


The combination of the CLF and CAF provides meaningful loudspeaker and amplifier specifications that are


1. Practical

2. Defensible

3. Platform-Independent

4. Manufacturer-Independent


for use by the professional audio industry. Finally there is a level playing field for those who must select and deploy electro-acoustic systems. Both formats can be used free-of-charge by manufacturers, software developers, and audio practitioners.


Some Other Milestones

Pat developed a non-destructive technique for measuring the maximum input voltage (MIV) to a loudspeaker. It uses a real-time dual-channel FFT measurement to compare the low voltage response of a loudspeaker to its response to higher voltages. Dubbed "the toaster test," Pat's method has been adopted by other testing labs and manufacturers, and incorporated into an AES Standard.


The Pro Sound Testing lab was the first to utilize a tri-hedral boundary  microphone using a room corner. This, combined with a ground plane measurement technique, allows a much greater measurement distance than can be achieved by a free-field placement in the same space. The tri-hedral microphone response is corrected to the response of a Type 1 free-field microphone, yielding an accuracy to within a fraction of a dB. Several manufacturers and test labs have adopted Pat's tri-hedral microphone technique.


A guiding force in the evolution of Pro Sound Testing has been a realization of the co-dependence between room acoustics measurements and acoustic prediction. Both of these must must work to the same end - the ability to predict the major performance attributes of a sound system at the drawing board. There exists a trade-off between "accuracy" and "generality" with regard to loudspeaker data. "More" is not necessarily "better" with regard to data resolution. Pro Sound Testing strives to make sure that the resolution is appropriate for the task at hand. This results in reduced simulation times, and better correlation between the modeled response of a system and measurements made of the finished system.


Our proprietary loudspeaker rotator (3rd generation). The device-under-test can be positioned for any desired point-of-rotation. The default measurement distance is 7.4 m, and the weight limit is in excess of 500 lbs.

Right - The "Motherload" is an 80 kW dummy load (3rd generation) for amplifier testing. It was designed and built by

Outdoor ground plane measurement of a cinema loudspeaker system. The individual component balloons were measured indoors and assembled in software.

Indoor free-field measurement, used to establish a reference response for the polar measurements.

"The Racks" - The left rack is for loudspeaker testing. The right rack is for amplifier testing.

Copyright 2015 - Pro Sound Testing, Inc. - All Rights Reserved