Influence of the Lip Horn on Acoustic Pressure Distribution Pattern of Sibilant /s/

Abstract

Influence of the lip horn on the acoustic pressure distribution of the sibilant /s/ wasexperimentally studied using avocal tract replica to which arectangular bafflewas added to represent ahuman face. The sound wasgenerated by asweep sound source (Frequency: 2-15 kHz)positioned at the inlet of the pharynx or by air flowing through the replica. The sound generated by the sweep source wasmeasured along twosemi-circles of radius 4cmevery 2 • (near-field)a nd radius 48 cm every 15 • (far-field), where as the sound generated by the floww as measured along semicircles of radius 10 cm every 2 • .From the normalized pressure distributions, it wasobserved that the lip horn enhances the pressure amplitude up to 15 dB at the center of the lips in both transverse and sagittal plane in the frequencyrange above 5kHz. The pressure distribution patterns measured with the acoustic source were similar to those measured with the flowsupply.This indicates that the pressure pattern of sibilant /s/ is affected by the vocal tract geometry rather than by the source characteristics.

Computational aeroacoustics to identify sound sources in the generation of sibilant /s/

“…The essentials of sibilant /s/ (see Jesus and Shadle) are thus well recovered, namely, the dip at mid‐frequencies followed by a positive spectral slope, the frequency position of the spectral peaks and the dynamic amplitude. More involved comparisons with experiments, like the directivity patterns in Yoshinaga et al, are left for future developments.…”

Finite element generation of sibilants /s/ and /z/ using random distributions of Kirchhoff vortices

“…The weak formulation (14) will be solved with FEM in this work to produce an /s/, and with some slight modifications on the boundary conditions to produce also a /z/. PONT ET AL.…”

“…A finite element approach has been followed for the spatial discretization of (14), while finite differences have been employed for the time discretization (see Section 3.1). In what concerns the former, it is well known that the Galerkin FEM fails to solve variational mixed problems like (14), unless tailored finite elements are designed to fulfill the corresponding inf-sup compatibility conditions. Such finite elements require different polynomial orders to approximate the acoustic pressure and particle velocity fields.…”

“…The stabilization parameters are obtained from a Fourier analysis of the subgrid scale equation (see, eg, previous studies 35,36,45,46 for details). Given a finite element partition of the computational domain Ω, with n el elements and n p nodes, and the finite dimensional spaces W h & H 1 Ω ð Þ and V 0h & V 0 , the discrete stabilized FEM approach to problem (14) consists in finding p h x, t ð Þ∈W h and u h x, t ð Þ∈W h , for all t > 0, such that…”

“…with C τ being a constant to be determined from numerical experiments (a value of C τ = 0.05 was taken in Guasch et al 36 ) and L 0 a characteristic length of the computational domain. The FEM formulation (15) should be next discretized in time to get the fully discrete approach to (14). However, prior to that, we need to address another issue.…”