Influence of acoustic loading on an effective single mass model of the vocal folds

Abstract

Three-way interactions between sound waves in the subglottal and supraglottal tracts, the vibrations of the vocal folds, and laryngeal flow were investigated. Sound wave propagation was modeled using a wave reflection analog method. An effective single-degree-of-freedom model was designed to model vocal-fold vibrations. The effects of orifice geometry changes on the flow were considered by enforcing a time-varying discharge coefficient within a Bernoulli flow model. The resulting single-degree-of-freedom model allowed for energy transfer from flow to structural vibrations, an essential feature usually incorporated through the use of higher order models. The relative importance of acoustic loading and the time-varying flow resistance for fluid-structure energy transfer was established for various configurations. The results showed that acoustic loading contributed more significantly to the net energy transfer than the time-varying flow resistance, especially for less inertive supraglottal loads. The contribution of supraglottal loading was found to be more significant than that of subglottal loading. Subglottal loading was found to reduce the net energy transfer to the vocal-fold oscillation during phonation, balancing the effects of the supraglottal load.

Investigating acoustic correlates of human vocal fold vibratory phase asymmetry through modeling and laryngeal high-speed videoendoscopy

“…The 70 kHz sampling rate is derived from C=(2A), where the speed of sound C ¼ 350 m=s. The model includes a radiation impedance (Story and Titze, 1995) and different loss factors for the subglottal and supraglottal tracts (Zañartu et al, 2007). The vocal tract area function is taken from 3D cine-MRI data of an adult male sustaining the =e= phoneme (Takemoto et al, 2006).…”

“…Additional model features, however, are implemented that are fundamental to the present acoustic investigation. In particular, nonlinear source-filter coupling between subglottal and supraglottal tracts is incorporated to account for acoustic coupling that has been shown to significantly affect source properties and system dynamics (Story and Titze, 1995;Zañartu et al, 2007;Titze et al, 2008;Titze, 2008). This coupling allows for observing the well-documented pulse skewing of the glottal airflow waveform, which is critical for determining spectral tilt and other acoustic characteristics (Doval and d'Alessandro, 2006).…”

Comments on single-mass models of vocal fold vibration

“…An analytic model by Zañartu et al (2007) for single-mass vocal fold oscillation grows out of the Park and Mongeau (2007) observations. The vocal folds are pictured as shutters that are rounded on the upstream side and squared-off on the downstream side.…”

Σύνθεση Φωνής Με Υπολογιστική Αεροδυναμική Ανάλυση Του Ανθρωπινού Ηχητικού Σωλήνα Και Σύγκριση Με Κλασσικές Μεθόδους

“…Οι αλλαγές αυτές είναι δυνατόν να προκαλούν μη γραμμικά φαινόμενα στην γλωττίδα, τα οποία μπορεί να φαίνονται στο ακουστικό σήμα της φωνής με την μορφή διαμορφώσεων. Υπάρ-χουν πολλές μελέτες στην βιβλιογραφία για την εμφάνιση δευτερευόντων διεγέρσεων στις φωνητικές χορδές και την ακουστική τους συσχέτιση [55,54,182].…”

“…Η συμπεριφορά του AMI σε σχέση με το ύψος του φωνήεντος, μπορεί να εξηγείται από αυτόν ακριβώς τον τρόπο άρθρωσης. Καθώς η γλώσσα πλησιάζει τον ουρανί-σκο δημιουργείται μια επιπλέον στένωση στην φωνητική οδό, και επομένως ένα επιπλέον σημείο εμφάνισης μη-γραμμικών φαινομένων ροής, όπως τυρβώδης / στροβιλώδης ροή του αέρα [183]. Παρόμοιες παρατηρήσεις αναφέρονται επίσης για τον γλωττιδικό παλμό, ο οποίος είναι περισσότερο ευαίσθητος στο ακουστικό φορτίο στα φωνήεντα /u/ και /i/ [2].…”