The Advanced Audio Systems Group is equipped with a variety of listening facilities for performing subjective tests or for conducting research in psychoacoustics. The Audio Perception Lab is a controlled environment for performing sensitive listening tests. Unique to North America, it is one of only a handful of such types of listening rooms anywhere in the world. A second facility, the Psychoacoustics Lab, is used for research and for doing hearing tests.

Audio Perception Lab

The Audio Perception Lab includes two separate listening rooms which provide a controlled listening environment for performing sensitive listening tests. Structurally separated from the building in which they reside, both listening rooms have a background noise rating below NR10. The acoustical properties of the two rooms can be varied to accommodate various desired listening conditions. In their typical configuration, the rooms' acoustics conform to ITU-R specifications described in Recommendation BS-1116.

The two listening room are adjacent to a control room which is equipped with a variety of professional digital audio equipment including Apogee DA8000 and Prism DA-1 AD/DA converters and the Mackie D8B digital mixer. Recording can be done on harddisk via Digital Audio Labs CardDOC or Sonorus StudIO digital audio cards or onto DAT. Multichannel digital recording can be done either onto Tascam DA-88 & DA-38 tape recorders or onto hard disks via the Sonorus StudIO card. For recording we are also equipped with a variety of Bruel&Kjaer and Audio Technica microphones.

The psychoacoustics lab is equipped with an audiometric chamber that enables precise measurement of the perception of low level signals and the discrimination of small differences between signals. Audio is computer-generated, and is presented to the listener via a Digital Audio Labs CardD digital sound card and an external Spectral Synthesis Model 2218D/A converter, and then to Stax SRM-1 headphones located in the audiometric chamber. A listener interacts with a computer screen through a window in the chamber using a mouse control.

Software to control listening tests and experiments was developed in-house. These include software to measure the hearing threshold and just noticeable differences in frequency, and software to conduct signal detection experiments for measuring the masked thresholds of signals in any audio context.