Perceptual Effects of Nasal Cue Modification

Acoustic or perceptual cues used for speech perception can be very helpful in almost all areas of speech signal processing. A new methodology 3-Dimensional-Deep Search and a new visualized intelligible time-frequency computerbased model AI-gram have been developed and are being researched since the last several years (Human Speech Recognition (HSR) research group at the University of Illinois Urbana-Champaign) for isolation of stable perceptual cues of consonants. The perceptual cues of nasal consonants [1] have been successfully found considering these techniques [1]. The previous work is extended by assessing the changes in nasal sound perception and cue region is modified by using digital signal processing method. The amplitude of the perceptual cue region is amplified, attenuated or ignored completely and then the perception score is measured. A high correlation between the amplitude of the cue region and the perception score is found. The intelligibility of the entire token is increased or decreased approximately in a similar fashion as the cue region modified amplitude which is measured by the MMSE shift of the perceptual score curve. This validates that the regions identified are perceptual cue regions for nasal consonants. The digital signal processing method proposed can be used as a new approach for enhancing speech signal in noisy conditions.