Factors in voice quality: Acoustic features related to gender

Attempts to measure the synthetic quality of speech usually consider the two factors intelligibility and naturalness, each involving subjective and objective characteristics. To generate high quality synthetic speech, spectral distortion should be avoided, spectral continuity and formant tracking should be done well. Glottal-related factors, including proper modeling of the 1) glottal excitation waveforms and 2) effects of source-tract interaction for synthesizers are discussed. Accurate detection of voiced/unvoiced/ silent segments in the speech waveform and the fundamental frequency of voicing are also major concerns. We present both formal and informal listener evaluations of three synthesizers: LPC, formant and articulatory. Finally, we suggest a two-channel, speech and electroglottograph (EGG), approach to speech analysis to aid the automatic processing of speech.