The estimation of formant frequencies from acoustic speech signals is mostly based on Linear Predictive Coding (LPC) algorithms. Since LPC is based on the source-filter model of speech production, the formant frequencies obtained are often implicitly regarded as those for an infinite glottal impedance, i.e., a closed glottis. However, previous studies have indicated that LPC-based formant estimates of vowels generated with a realistically varying glottal area may substantially differ from the resonances of the vocal tract with a closed glottis. In the present study, the deviation between closed-glottis resonances and LPC-estimated formants during phonation with different peak glottal areas has been systematically examined both using physical vocal tract models excited with a self-oscillating rubber model of the vocal folds, and by computer simulations of interacting source and filter models. Ten vocal tract resonators representing different vowels have been analyzed. The results showed that F1 increased with the peak area of the time-varying glottis, while F2 and F3 were not systematically affected. The effect of the peak glottal area on F1 was strongest for close-mid to close vowels, and more moderate for mid to open vowels.
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July 2019
July 17 2019
How the peak glottal area affects linear predictive coding-based formant estimates of vowels
Peter Birkholz;
Peter Birkholz
a)
1
Institute of Acoustics and Speech Communication, TU Dresden
, 01062 Dresden, Germany
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Falk Gabriel;
Falk Gabriel
1
Institute of Acoustics and Speech Communication, TU Dresden
, 01062 Dresden, Germany
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Steffen Kürbis;
Steffen Kürbis
1
Institute of Acoustics and Speech Communication, TU Dresden
, 01062 Dresden, Germany
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Matthias Echternach
Matthias Echternach
2
Division of Phoniatrics and Pediatric Audiology, Department of Otorhinolaryngology, Munich University Hospital, LMU
, Munich, Germany
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a)
Electronic mail: peter.birkholz@tu-dresden.de
J. Acoust. Soc. Am. 146, 223–232 (2019)
Article history
Received:
January 23 2019
Accepted:
June 20 2019
Citation
Peter Birkholz, Falk Gabriel, Steffen Kürbis, Matthias Echternach; How the peak glottal area affects linear predictive coding-based formant estimates of vowels. J. Acoust. Soc. Am. 1 July 2019; 146 (1): 223–232. https://doi.org/10.1121/1.5116137
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