Sound propagation and radiation in a curved duct

Malbéqui, P.; Glandier, Christian; Reynier, C.

doi:10.2514/3.13307

Cited by 7 publications

(2 citation statements)

References 11 publications

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“…Notably, the direction of the frequency shift is frequency dependent ( Félix et al, 2012 ). The acoustics of these curved ducts were largely established through the examination of hard walled materials or rigid ducts which are assumed not to absorb acoustic energy ( Cabelli, 1980 ; Malbéqui et al, 1996 ). Literature in music has reported that the wall materials of the wind instruments have influence on the quality of produced tones, such as damping or frequency amplification (see Bucur, 2019 for reviews).…”

Section: Introductionmentioning

confidence: 99%

Tongue Postures and Tongue Centers: A Study of Acoustic-Articulatory Correspondences Across Different Head Angles

2022

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Recent research on body and head positions has shown that postural changes may induce varying degrees of changes on acoustic speech signals and articulatory gestures. While the preservation of formant profiles across different postures is suitably accounted for by the two-tube model and perturbation theory, it remains unclear whether it is resulted from the accommodation of tongue postures. Specifically, whether the tongue accommodates the changes in head angle to maintain the target acoustics is yet to be determined. The present study examines vowel acoustics and their correspondence with the articulatory maneuvers of the tongue, including both tongue postures and movements of the tongue center, across different head angles. The results show that vowel acoustics, including pitch and formants, are largely unaffected by upward or downward tilting of the head. These preserved acoustics may be attributed to the lingual gestures that compensate for the effects of gravity. Our results also reveal that the tongue postures in response to head movements appear to be vowel-dependent, and the tongue center may serve as an underlying drive that covariates with the head angle changes. These results imply a close relationship between vowel acoustics and tongue postures as well as a target-oriented strategy for different head angles.

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Section: Introductionmentioning

confidence: 99%

Tongue Postures and Tongue Centers: A Study of Acoustic-Articulatory Correspondences Across Different Head Angles

2022

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“…However, at present time, they are still limited to the low frequency range, due to the CPU time requirement. The Boundary Element Method (BEM) is applicable over almost the entire frequency range of interest, assuming a homogeneous flow in the radiated far-field [12]. As an approximation to the BEM, the fast multi-pole method allows realistic configurations in aero-acoustics to be modeled, including the shielding effects [8].…”

Section: Introductionmentioning

confidence: 99%

Capabilities of the high-order parabolic equation to predict propagation in boundary and shear layers.

Malbéqui

Simon‐Christien

2010

The Journal of the Acoustical Society of America

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T he so-called parabolic equation (PE) has proved its capability to deal with the long range sound propagation as an alternative to the ray model. It was shown that the High-Order Parabolic Equation (HOPE), based on a Padé expansion, significantly increases the aperture angle of propagation, compared to the standard PE and the wideangle PE. As a result, for the in-duct propagation it allows us an accurate prediction close to the cut-off frequency. This paper concerns the propagation using the HOPE in heterogeneous flows, including a boundary layer above a hard wall and in shear layers. The thickness of the boundary layer is some dozens of centimeters while, outside of it, the Mach number can reach 0.5. The flow effects are investigated showing the refraction effects at a propagation distance of 30 meters, up to a few kilohertz. Significant discontinuities in the directivity patterns occur in the shear layer. Comparisons with the Euler solution are considered, including configurations beyond the theoretical limits of the HOPE.

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