Perceptual sensitivity to first harmonic amplitude in the voice source

Area of Science:

• Acoustic Phonetics
• Speech Perception
• Psychoacoustics

Background:

• Perceptual importance of source spectral shape remains unclear.
• Various acoustic measures correlate with vocal qualities like breathiness and roughness.
• Understanding harmonic amplitude perception is key to vocal quality analysis.

Purpose of the Study:

• Investigate just-noticeable differences (JNDs) in the relative amplitudes of the first two harmonics (H1-H2).
• Determine the perceptual validity of the H1-H2 measure for vocal quality.
• Compare sensitivity to harmonic amplitude changes between Mandarin and English speakers.

Main Methods:

• Listeners judged voice quality based on pairs of vowels differing in the first harmonic's amplitude.
• Just-noticeable differences (JNDs) in H1-H2 amplitude were measured.
• Data collected from Mandarin and English speaking participants.

Main Results:

• Average JND for H1-H2 was 3.18 dB, indicating perceptual relevance.
• Detection of harmonic amplitude differences was easier with steeply falling spectral slopes (F0 dominance).
• Mandarin speakers demonstrated significantly higher sensitivity (approx. 1 dB lower JND) than English speakers.

Conclusions:

• The H1-H2 amplitude ratio is a perceptually valid acoustic measure of vocal quality.
• Mandarin speakers' enhanced sensitivity may stem from experience with tonal contrasts and voice quality.
• Findings suggest linguistic experience can influence auditory perception of voice features.