Glottal Waves via Inverse Filtering of Vowel Sounds

Area of Science:

• Acoustic phonetics
• Speech production
• Bioacoustics

Background:

• Accurate glottal wave estimation is crucial for understanding speech production.
• Traditional inverse filtering methods can be confounded by vocal tract resonances.
• Incomplete glottal closure introduces artifacts in glottal wave analysis.

Purpose of the Study:

• To develop a method for obtaining accurate glottal waves via inverse filtering.
• To identify and minimize vocal tract filter (VTF) resonance in glottal wave estimation.
• To analyze glottal wave characteristics during different phases of the glottal cycle.

Main Methods:

• Inverse filtering of sustained vowel sounds using a novel method.
• Estimating vocal tract filter (VTF) parameters during closed glottal phases.
• Minimizing the influence of glottal source characteristics on VTF estimation.
• Simulating residual resonance patterns in glottal wave derivatives.

Main Results:

• A new method effectively minimizes vocal tract resonance in inverse-filtered glottal waves.
• Simulations demonstrate residual resonance appearing as stationary ripples on glottal wave derivatives.
• Glottal waves and VTF estimates were successfully obtained for sustained /a/ vowels from male and female speakers.
• Derivatives of glottal waves showed distinct transient peaks during vocal fold collision and negative levels during parting.

Conclusions:

• The proposed method enhances the accuracy of glottal wave estimation.
• The findings provide insights into distinguishing glottal source features from vocal tract effects.
• This technique aids in the detailed analysis of vocal fold dynamics and speech acoustics.