Synthesis of Hindi consonants with natural sounding quality using the PC-based Klatt synthesizer

Abstract

This paper describes experiments conducted to synthesize Hindi consonants with natural sounding quality using the PC-based Klatt synthesizer. All the most frequently used 29 Hindi consonants have been synthesized in the form of CV and VC syllables. For this purpose, a detailed spectral analysis was carried out to determine minute acoustic differences among the various categories of consonants such as unaspirated/aspirated, voiced/unvoiced, dental/retroflex, liquid/trill, etc.. The synthesis was done using a modified version of the Klatt Synthesizer simulated on a PC. It uses about 60 parameters for the source and vocal tract variations in 5-ms duration. Variations in important parameters were made until a satisfactory quality of consonant was perceived and a clear distinction occurred with its cognate sound. For example, the distinction among dental plosives (t, th, d, dh) and retroflex plosives (t*, th*, d*, dh*) have been achieved by changing formant frequencies at the burst position, intensity of burst, and formant transitions from burst to the target vowel. Similarly the sound /r/ in Hindi takes various forms such as trill or fricative depending upon the context. This is a very special characteristic of /r/ in Hindi. In this same manner the special features of all the 29 consonants are discussed with references to their synthesis in five different vowel contexts.