CALIBRATION OF ACOUSTICAL STIMULATION IN AUDITORY EVOKED RESPONSES (AER) RECORDING
A.V.Kruglov, O.A.Belov, G.A.Tavartkiladze
Research Centre for Audiology and Hearing Rehabilitation
Moscow, Russia
In auditory evoked responses recording usually both short acoustic clicks (60-100 ms) and short tone bursts or tone pips of various frequencies are used. Measurement of the intensity of these stimuli with the use of peak SPL doesn't provide precise evaluation of their power. That is why the application of insert phones for AER recording is of importance.
We have developed a method where along with the insert phones the microphone channel is used for AER recording. The channel consists of a miniature electret microphone and a sound conducting tube (similar to those used in impedance and otoacoustic emission measurements). The channel in question is used for the evaluation of the stimulus intensity. The channel is calibrated in the acoustical chamber against the reference microphone (B & K measuring microphone). The main error source in the above approach to the stimulus intensity measurement is the emergence of a standing wave in the external ear canal. However the proper ear mould design and sound conducting tube length will minimize this effect at the frequencies up to 5 kHz.