Compressive sensing based spherical harmonics decomposition of a low frequency sound field within a cylindrical cavity

2017 ◽  
Vol 141 (3) ◽  
pp. 1812-1823 ◽  
Author(s):  
Yan Wang ◽  
Kean Chen
Keyword(s):  
Compressive Sensing ◽  
Spherical Harmonics ◽  
Cylindrical Cavity ◽  
Low Frequency ◽  
Sound Field ◽  
Frequency Sound

scholarly journals Low Frequency Sound Field Reproduction within a Cylindrical Cavity Using Higher Order Ambisonics

2018 ◽  
Vol 36 (4) ◽  
pp. 649-655
Author(s):  
Yan Wang ◽  
Kean Chen ◽  
Jian Xu
Keyword(s):  
Green Function ◽  
Spherical Harmonics ◽  
Cylindrical Cavity ◽  
Microphone Array ◽  
Low Frequency ◽  
Sound Field ◽  
High Order ◽  
Acoustic Modes ◽  
The Green Function ◽  
Order Components

Sound field reproduction of the aircraft and submarine within a cabin mock-up using a loudspeaker array is of great importance to the active noise control technology.The conventional method is to calculate the driving functions of the secondary sources by solving an acoustic inverse problem in a least square sense, which requires a large number of microphones and only the sound field near the microphone array can be reproduced accurately.In order to overcome these drawbacks, higher order ambisonics (HOA) method which is widely used in spatial sound field synthesis for a large room is introduced to reproduce a low frequency sound field within a cylindrical cavity.Due to the different sound propagation characteristics within the cavity compared with a free field and a diffuse field, the Green function spectrum in spherical harmonics domain which is modeled as a superposition of the acoustic modes and the reproduction formulas are deduced.Reproduction characteristics are investigated by numerical simulations.Results show that for a small, the Green function spectrum in spherical harmonics domain is mainly concentrated on low orders and contributed by the low order acoustic modes, with the increase of, high order components of the Green function arise and the contributions of high order acoustic modes increase.In the reproduction process, the high order components of the pressure spectrum over the sphere in harmonics domain will be greatly amplified by the reproduction filter.Finally, HOA method is compared with the acoustic inversion method in terms of the microphone array system, the impact factors on the reproductions and the reproduction accuracy, and validated through experiments.Results show that HOA can better reproduce the entire sound field within the cylindrical cavity and the reproduction accuracy is improved.

Low Frequency Sound as a Navigational Tool for People with Visual Impairments

2002 ◽  
Vol 21 (4) ◽  
pp. 199-205 ◽  
Author(s):  
Daniel Ashmead ◽  
Robert Wall
Keyword(s):  
Wall Motion ◽  
Visual Impairments ◽  
Low Frequency ◽  
Sound Field ◽  
Frequency Sound ◽  
Acoustic Information ◽  
Large Structures ◽  
Dominant Feature ◽  
Mistaken Assumption ◽  
Navigational Tool

For decades, a mistaken assumption in the habilitation of travel for people with visual impairments has been that the use of “echolocation” is a dominant feature of acoustic information for the guidance of locomotion. This paper outlines a theoretical model of acoustic information available in many travel situations. The acoustic information consists of a build up of low frequency sound along large structures such as walls. Useful frequencies are low enough that the experience of this build up is often one of feeling rather than hearing. Experimental validation of this model was accomplished by having participants with visual impairments walk along walls with varying types of auditory occlusion and through laboratory based manipulations of acoustic information. Results indicate that the model is appropriate. Useful acoustic information appears to extend up to 1 m from a wall. There is strong evidence that participants make use of binaural information, gauging the similarity of acoustic information reaching each ear to maintain orientation to a wall. Motion through the sound field near the wall makes the information more useful but it is unclear whether motion in certain directions or conditions is more useful than others.

A simple acoustic model to characterize the internal low frequency sound field in centrifugal pumps

2011 ◽  
Vol 72 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Jorge Parrondo ◽  
Javier Pérez ◽  
Raúl Barrio ◽  
José González
Keyword(s):  
Low Frequency ◽  
Sound Field ◽  
Acoustic Model ◽  
Centrifugal Pumps ◽  
Frequency Sound

Low-frequency sound field in a room with a Helmholtz resonator

2000 ◽  
Vol 46 (4) ◽  
pp. 491-493 ◽  
Author(s):  
A. D. Lapin
Keyword(s):  
Low Frequency ◽  
Sound Field ◽  
Helmholtz Resonator ◽  
Frequency Sound

Active Control of Low-Frequency Sound Radiation From Vibrating Panel Using Planar Sound Sources

2001 ◽  
Vol 124 (1) ◽  
pp. 2-9 ◽  
Author(s):  
Kean Chen ◽  
Gary H. Koopmann
Keyword(s):  
Active Control ◽  
Near Field ◽  
Low Frequency ◽  
Sound Radiation ◽  
Sound Field ◽  
Sound Power ◽  
Frequency Range ◽  
Sound Sources ◽  
Frequency Sound ◽  
Secondary Sources

Active control of low frequency sound radiation using planar secondary sources is theoretically investigated in this paper. The primary sound field originates from a vibrating panel and the planar sources are modeled as simply supported rectangular panels in an infinite baffle. The sound power of the primary and secondary panels are calculated using a near field approach, and then a series of formulas are derived to obtain the optimum reduction in sound power based on minimization of the total radiate sound power. Finally, active reduction for a number of secondary panel arrangements is examined and it is concluded that when the modal distribution of the secondary panel does not coincide with that of the primary panel, one secondary panel is sufficient. Otherwise four secondary panels can guarantee considerable reduction in sound power over entire frequency range of interest.

Abnormal interference of very low frequency sound field in shallow water

2021 ◽  
Vol 150 (4) ◽  
pp. A317-A317
Author(s):  
Shengchun Piao ◽  
Yang Dong ◽  
Zhiqiang Wu
Keyword(s):  
Shallow Water ◽  
Low Frequency ◽  
Sound Field ◽  
Very Low Frequency ◽  
Frequency Sound

The application of vertical sound intensity in shallow and low frequency sound field

2011 ◽  
Author(s):  
Sheng Xue Li ◽  
Mei Ji Dan ◽  
Guo Yong ◽  
Yin Jing Wei ◽  
Guo Long Xiang
Keyword(s):  
Low Frequency ◽  
Sound Field ◽  
Sound Intensity ◽  
Frequency Sound ◽  
Vertical Sound
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