The time scale modification (TSM) of speech is concerned with the compressing or expanding of audio signals in the time domain without affecting the signals pitch or naturalness. Conversely, the frequency scale modification (FSM) of speech is concerned with altering the pitch and formants of a signal without changing the signal duration. This paper describes a hardware implemented and optimized TSM/FSM system. Biomedical speech related applications for such a system include accelerated aural reading for the blind and improved speech recognition – In a voice controlled robotic system for the disabled, the speech can be effectively “slowed down” to improve the recognition rate. Other applications of the system include speech synthesis, foreign language learning, audio typing, and voice transformation.

Index Terms. TSM, FSM, VLSI