There is a large (64m3) anechoic chamber in the main auditory laboratory. This is fitted out for a whole range of bioacoustic, psychophysical and neurophysiological investigations. This chamber is anechoic to 150Hz (better than 99% absorption) and has an insertion loss of better than 30dB for sound frequencies greater than 100Hz rising rapidly to greater than 60dB above 500Hz.
The anechoic chamber is equipped with a robot arm carrying a small speaker that can be placed at any location on the surface of an imaginary sphere surrounding a test subject located in the middle of the chamber. The robot arm is:
A second laboratory is equipped with a double walled audiometric booth large enough for a whole range of virtual space localization experiments as well as more traditional psychophysical procedures.
The stimulus generation system is DSP based and capable of generating arbitrary complex signals with a very high degree of control over time and frequency domain characteristics. The system capabilities include:
Data capture is also A/D based allowing direct to disk recording as well as extensive signal processing and data manipulation. Impulse response function measurements involve Golay code stimuli and stimulus locked averaging to increase S:N together with on-line display of time and frequency domain (amplitude and phase) characteristics of system responses.
All aspects of the stimulus delivery and data capture systems are fully automated and computer controlled. This results in a highly flexible system capable of achieving highly reproducible bioacoustic recordings.
For bio-acoustic measurements the objects being measured (eg human ears) are aligned in the hoop coordinate system using a laser alignment system. In human bio-acoustic and behavioural experiments the position of a subjects head is tracked in real time using a 6 degrees of freedom electromagnetic tracking system with mm resolution and 0.1 degree orientation accuracy.
Return to the index.