Observation and modelling of glottal biphonation
Abstract:Digital high-speed camera technique combined with laryngoscopy was used to observe vocal fold vibration in a normal subject and a patient with paralysis of the recurrent nerve who were able to phonate simultaneously at two different pitches. This phenomenon is called biphonation. Previous clinical examinations of biphonation and diplophonia will be compared with our observations. Moreover, we employed a modified two-mass model of the vocal folds in order to fit simulated time series to the high-speed glottograms (HGG) extracted by image processing from the digital picture sequences. By variation of the model parameters we generated waveforms which showed the characteristic features of biphonation. We state that the appearence of to independent pitches bases on biperiodic or toroidal oscillations of the vocal folds. The main condition for biphonation is a laryngeal asymmetry causing a desynchronization of the vocal fold oscillations which is reinforced by high pitched phonation, incomplete closure and large subglottal pressure.
We stress the importance of a combined application of high-speed camera technique and model simulations to explain the mechanisms of hoarseness. It is a very succesfull method to isolate physiological parameters which categorize and quantify vocal disorders.
Document Type: Research Article
Publication date: 1997-07-01
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- Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.
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