Computational aeroacoustics to identify sound sources in the generation of sibilant /s. (9th October 2018)

• Record Type: Journal Article
• Authors: Pont, Arnau; Guasch, Oriol; Baiges, Joan; Codina, Ramon; van Hirtum, Annemie
• Is Part Of: International journal for numerical methods in biomedical engineering. Volume 35:Number 1(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-10-09
• Subjects: computational aeroacoustics -- finite elements -- fricatives -- large eddy simulation -- Lighthill; Biomedical engineering -- Periodicals; Imaging systems in medicine -- Periodicals; Numerical analysis -- Periodicals; Engineering mathematics -- Periodicals; 610.28
• DOI: 10.1002/cnm.3153
• Languages: English
• ISSNs: 2040-7939

Abstract

Abstract: A sibilant fricative /s/ is generated when the turbulent jet in the narrow channel between the tongue blade and the hard palate is deflected downwards through the space between the upper and lower incisors and then impinges the space between the lower incisors and the lower lip. The flow eddies in that region become a source of direct aerodynamic sound, which is also diffracted by the speech articulators and radiated outwards. The numerical simulation of these phenomena is complex. The spectrum of an /s/ typically peaks between 4 and 10 kHz, which implies that very fine computational meshes are needed to capture the eddies producing such high frequencies. In this work, a large‐scale computation of the aeroacoustics of /s/ has been performed for a realistic vocal tract geometry, resorting to two different acoustic analogies. A stabilized finite element method that acts as a large eddy simulation model has been adopted to solve the flow dynamics. Also, a numerical strategy has been implemented that allows the determination, in a single computational run, of the separate contribution of the sound diffracted by the upper incisors from the overall radiated sound. Results are presented for points located close to the lip opening showing the relative influence of the upper teeth depending on frequency. Abstract : A parallel large‐scale computation of sibilant fricative /s/ has been performed for a realistic vocal tract geometry, resorting to two different acoustic analogies. The separate contributions from the direct turbulent sound and that diffracted by the upper incisors have been identified. A stabilized finite element strategy that allows one obtaining the flow dynamics and the direct turbulent and diffracted sound in a single computational run has been implemented.