Deaf Speech Assessment Using Digital Processing Techniques

Abstract

This paper mainly deals with analysis on acoustical characteristics of speeches of deaf people for the purpose of increasing the speech recognition rate. Since speech to text or sound system for a normal speaker is available, by designing a speech to text or sound system for deaf, they can make use of all computer aided devices and normal speakers can also communicate with them freely. Fundamental frequency or the pitch frequency of the vocal fold and resonant frequency of the vocal tract or formants are considered for analysis which are the foremost characteristics of speech. Compared to normal speech, there is a high variability in deaf speech and by hearing once we couldn't understand it. Deaf speech is taken from children in the age group of 5-10 years from Maharishi vidya mandir centre for hearing impaired. Another set of speech were taken from normal speakers for comparison. Initially the input is sampled, filtered, windowed and Pitch frequency is determined for each frame. Similarly first six formants are determined for each frame. The fundamental frequency contour of deaf children exhibit unusual characteristics, and the formants are also very closed. This shows that, pitch and formants cannot be used as features for deaf speech recognition. At the same time, variation in the pitch and formants for deaf is larger than normal speakers it can be used for speaker classification purpose.