Digital Telephone Equalizer for Deaf People
Copyright 1999 by Igor Trevisan in cooperation with BLUEWIND
Introduction
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Digital Telephone Equalizer for Deaf People Copyright 1999 by Igor Trevisan in cooperation with BLUEWIND |
| Introduction
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Background
Deafness is a widely dffused invalidant factor that affects, with different incidences, people of different ages, sex and geographical provenience. The gravity of this deficiency stands in the inevitable limitation of social relations which result complicated when not precluded. We have to consider then that the telephone represents a further barrier for deaf people, whether they use a prosthesis or not, because it modifies the speech signal making it less understandable.
According to what we have already said and to the documentation you can find in [12] and [13] for instance, comes the necessity to approach deaf people again with the use of telephone. We need not only to amplify the signal to make it audible, but we also have to elaborate it, with a right equalization, to compensate the anomalies of the auditory line, succeeding in this way to to make the transmitted message intelligible.
Results
In the thesis presented here the software regarding signal processing has been developed for an Analog Devices' DSP Evaluation Board. The obtained equalization system, based on a ADSP2181 fixed point 16-bit Dsp, permits a great variety of possible regulations, being at the same time flexible and easy to use, and it assures a SNR of about 50dB at the output. Moreover it's possible to obtain a different setting for right and left ear. The final test arranged with a subject affected by strong hypoacusia, with a first version of the prototipe, gave a "satisfactory result" according to the deaf subject. This positive checking, along with wider medical verification, brings the strong request to develop a series of correlated accessories dedicated to a hearing personalization.
Conclusions
It seems feasible to start adopting this system with plugs to hear on loud-speaker, amplified receiver, phones and acoustic prosthesis for serious and particular hearing desease; the natural evolution could be the development of a new type of telephone appliance, whose signal characteristiscs may be kept configurable by a personal data storage mean (like bar code card, memory credit card or equivalent device), containing all the personal acoustic parameters of the deaf subject.
This kind of telephone set would enable the hypoacusical subject to easily adapt the appliance to his own needs.