Our first air-conditioning silencers were developed in 1950. Since then, IAC has pioneered the development of performance-rated silencers to ensure quiet Air Handling Systems. To maintain this position of leadership, IAC has operated, since the early 50's, fully equipped state of the art Aero-Acoustic Laboratories. These facilities are not only used for the development of new silencers and other noise control products, but also for quality control purposes.

In 1965, for the first time in the noise control industry, IAC offered duct silencers accurately rated for acoustic performance with air flowing through them. IAC introduced the term "Dynamic Insertion Loss" (DIL) to report noise reduction with airflow, and "Self-Noise" to describe the noise generated by the air flowing through the silencer itself. Furthermore, aerodynamic and acoustical performance was measured in one test facility, on the same silencer, and under specified repeatable conditions.

In 1972, IAC developed silencer Dynamic Insertion Loss and Self-Noise ratings both under Forward Flow(+) and Reverse Flow (-) conditions for Rectangular and Cylindrical Silencers. Forward Flow occurs when air and sound-waves travel in the same direction, as in an air-conditioning supply system or a fan discharge. Reverse Flow occurs when sound-waves and air travel in opposing directions, as in a typical return-air system.