The Contribution of Nasal Murmur to the Perception of Nasal Consonant

Identification of perceptual cues can be very helpful in almost all areas of speech signal processing. Recently, a new methodology called the 3-Dimensional-Deep Search and a visualized intelligible time-frequency computer-based model AI-gram is invented for research on the perceptual cues. Based on this technique, the acoustic cues for stop conso- nants (1), fricative consonants (2) and nasal consonants (3) are successfully found. However, it has limitations on studying the contribution of nasal murmur to the recognition of nasal consonants due to the following reasons: Firstly, it only al- lows the investigating of individual recognition effects along the time, frequency and amplitude axes. The effects of fre- quency and amplitude in a combinatorial way cannot be studied. Secondly, the initial value for the high-pass filter in the filter experiment HL07 (4) is set to be 697 Hz, but the nasal murmur region lies around 250 Hz. The perceptual contribu- tion of nasal murmur to the nasal consonants cannot be assessed. To solve these problems, a new experiment is designed by analyzing experiment data and comparing them with the stimuli under different SNRs via AI-gram. It is revealed that when the primary cue of nasal consonant is clear, which is usually under high SNRs, filtering out nasal murmur does not affect its correct perception. However, when the primary cue is weak usually under low SNRs, nasal murmur has strong complementary effects on the primary cue, and can greatly suppress confusions. This conclusion can be used for noise- robust speech recognition.