Facilities

The laboratory specializes on spatial hearing and the effects of assistive devices on hearing in 3-D environments. It allows researchers to study binaural hearing and the processing of signals in noise. This laboratory is also available to industry research.

The word "anechoic" literally means "without echo" and to achieve this specific condition, the chamber is built of specialized material to minimize sound reflection and external noise. The interior room measures approximately 18 feet high by 23 feet wide by 12 feet deep, and is equipped with a 125 Hz cut-off wedge system on the walls and ceiling and removable sound absorbing panels on the floor. The exterior walls are composed of thick cement and are covered with reflective material to prevent outside noise from entering the chamber. This facility supports a wide range of research projects requiring a highly-controlled sound field environment. Researchers in the fields of Music, Audiology, Hearing Science, and Engineering all make use of this facility.

The Anechoic Soundfield Testing Facility is one of the largest in Canada. The intensity, spectral content and temporal characteristics of audio stimuli at each of 64 speakers in this hemi-anechoic chamber are precisely controlled through custom software and a 64-channel realtime digital signal processing system. The system is versatile and provides an ideal environment for measuring the electroacoustic characteristics of hearing aids and assistive hearing devices, and for studying auditory perception in a controlled or simulated 3-D environment. The chamber is fully functional for the electroacoustic evaluation of directional hearing aids, microphone arrays, and sound alarm medical equipment.

A custom designed turntable and rotatable vertical loudspeaker array allow stimuli to be presented in a continuous spatial array, allowing accurate characterization of the directional performance of hearing devices and the study of vertical sound localization in humans. A 32-channel spherical microphone array allows the capture of the 3-D characteristics of real soundfields and their reconstruction in the laboratory using the multi-loudspeaker system.

The Reverberation Chamber simulates reverberant environments and is similarly equipped to the anechoic chamber, making protocols portable between environments. Significant reverberation as may be encountered in churches, airport terminals, gymnasia and large classrooms, reduces speech intelligibility and increases listening effort, especially for those with hearing impairment. While technologies are now available to effectively deal with interference from noise, we remain relatively unable to deal with reverberation which adds temporal interference to signals.

Assessment of speech-in-noise performance of many listeners has revealed a population of hearing impaired listeners whose hearing is similar but who have exceptionally poor performance in reverberation but not under anechoic conditions.

Researchers can simulate various listening situations in a controlled 3-D environment to assess the electroacoustic and perceptual benefits of new hearing aid processing algorithms or assistive devices.