Evaluation of bandwidth extension of telephony speech by data hiding in three languages

Telephone systems commonly transmit narrowband (NB) speech with a bandwidth limited to 200-3500 Hz. Since human speech contains frequencies even beyond the NB, there is a degradation of speech quality and intelligibility in such systems. This can be improved by regenerating the audible components existing outside the telephone bandwidth which are transmitted to the receiver by hiding them into the NB signal. In this paper, the performance of bandwidth extension (BWE) of telephony speech by data hiding method was assessed by auditory and instrumental tests in English, Hindi, and Telugu languages. The Data hiding method was found to improve the telephony speech quality and intelligibility in all the evaluated languages.