This tool is a cheap way to teach simple audiometry. However, before any such use is possible, the platform/headphone combination MUST be properly calibrated. An unreliable but quick method is to use one or (preferably) more individuals with normal hearing. It will be necessary to modify the Matlab code to introduce the new levels. Also note that the code assumes a 30dB suppression on the audio path (to reduce line noise levels). If no suppression is used, the relevant line of code (easily spotted) should be commented out.
Type 'audiometer' to start the tool. Select an ear of presentation (1), a frequency (2), then adjust the level (3) and listen to the tone (4) until the tone is no longer audible (consult an audiometric expert to determine the appropriate procedure for gauging the threshold, or simply converge on the threshold by repeatedly adjusting the level in smaller increments either side of audibility). When you are satisfied, record the threshold (5) and select another ear/frequency. When a complete set of measurements is obtained for one or other ear, the measurements will be joined by a line, although they may still be adjusted subsequently.
The dotted line at 20 dB HL represents 'normal' hearing. Any point below this line represents a hearing loss.
Produced by: Martin Cooke, based on specifications by David McAlpine (Biological Sciences, Sheffield). Thanks to John (Medical Physics, Sheffield) for calibration facilities and advice.
Release date: Jan 19 1999
Permissions: This demonstration may be used and modified freely by anyone. It may be distributed in unmodified form.