HearLoss is an interactive Windows PC program for demonstrating to normally hearing people the effects of hearing loss. With HearLoss you can replay speech, music and noise under a variety of loudness, filtering and masking conditions typical of hearing impairments. Best of all you can interactively change the settings and demonstrate their consequences.
The HearLoss program plays back pre-recorded audio samples of some speech, some music and some typical background noise, either singly or in combination. As it replays, three sliders control a simulation of the effects of three common consequences of hearing loss: loss in amplitude sensitivity, reduction in frequency range, and loss in spectral detail. Changes in the amplitude sensitivity slider changes the loudness of the sound, changes to the frequency range slider changes the upper frequency limit of the sound, while changes to the spectral detail slider changes the amount of fine structure present in the spectrum.
This is one way you might use the program to demonstrate the effects of hearing loss to normally-hearing people:
Start the music playing and adjust levels so that the audience can hear it clearly. Stop the music.
Explain that deafness is not just all or nothing, but that hearing impairments come in various degrees.
Play music and demonstrate loss in amplitude sensitivity to mild, moderate and severe losses.
Repeat for speech. Point out that difficulty in hearing speech affects our social interactions – we can’t follow what is going on in a group conversation, for example.
Explain that if hearing loss was just a loss in sensitivity, then we could restore peoples’ hearing with just an amplifier.
Explain that most hearing loss is not just a drop in quantity but also a dop in the quality of sound perceived. In particular the kind of hearing impairment asoociated with old age has associated changes in frequency range and spectral detail.
Play music and demonstrate what a reduction in frequency range means: at mild, moderate and severe levels.
Repeat for speech. Point out that even if the speech were loud enough, the loss of high frequencies makes it harder to understand.
Play music and demonstrate the consequences of a loss in spectral detail. The effect of this slider is like looking at an out-of-focus photograph – you can’t see all the fine detail. Get the audience to listen as you bring the slider back to normal – you should hear the signal getting "clearer".
Play speech and noise simultaneously with sliders set to normal. Point out that the speech is still fairly easy to understand.
Add a moderate loss of frequency range and spectral detail. The speech is pretty unintelligible now, although it becomes a bit clearer when the noise is turned off. Hearing impaired people find listening in conditions of noise far more difficult than normally hearing people.
HearLoss is not public domain software, its intellectual property is owned by Mark Huckvale, University College London. However HearLoss may be used and copied without charge as long as the program remains unmodified and continues to carry this copyright notice. Please contact the author for other licensing arrangements. HearLoss carries no warranty of any kind, you use it at your own risk.