Localizing Lung Sounds: Eigen Basis Decomposition for Localizing Sources Within a Circular Array of Sensors

Salehin, S. M. Akramus; Abhayapala, Thushara D.

doi:10.1007/s11265-009-0435-3

Cited by 6 publications

(6 citation statements)

References 35 publications

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“…1 This modal decomposition has the advantage of separating components dependent on the source position form those dependent on the sensor position and thus found application in direction of arrival (DOA) estimation 16 and in biomedical acoustic source localization within circular sensor arrays. 17,18 …”

Section: A Wavefield Decompositionmentioning

confidence: 99%

“…By comparing (17) to (10), the spherical Fourier transform of the aperture response for order n and mode m is (15). The advantage of choosing separable basis expansions for the radial and angular components in both the wavefield modal expansion and the spatial distribution expansion allows the integration over a spherical volume V to be separated to two independent integrals (16).…”

Section: Spherical Fourier Bessel Expansion Of Spatial Distributionmentioning

confidence: 99%

“…One of these integrals is over the radial parameter while the other is over the angular parameter. Further, the separation of integrals allows the exploitation of the orthogonality property of the spherical harmonic functions reducing summation over four parameters to summation over two (17).…”

Section: Spherical Fourier Bessel Expansion Of Spatial Distributionmentioning

confidence: 99%

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Frequency-radial duality based photoacoustic image reconstruction

Salehin

Abhayapala

2012

The Journal of the Acoustical Society of America

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Photoacoustic image reconstruction algorithms are usually slow due to the large sizes of data that are processed. This paper proposes a method for exact photoacoustic reconstruction for the spherical geometry in the limiting case of a continuous aperture and infinite measurement bandwidth that is faster than existing methods namely (1) backprojection method and (2) the Norton-Linzer method [S. J. Norton and M. Linzer, "Ultrasonic reflectivity imaging in three dimensions: Exact inverse scattering solution for plane, cylindrical and spherical apertures," Biomedical Engineering, IEEE Trans. BME 28, 202-220 (1981)]. The initial pressure distribution is expanded using a spherical Fourier Bessel series. The proposed method estimates the Fourier Bessel coefficients and subsequently recovers the pressure distribution. A concept of frequency-radial duality is introduced that separates the information from the different radial basis functions by using frequencies corresponding to the Bessel zeros. This approach provides a means to analyze the information obtained given a measurement bandwidth. Using order analysis and numerical experiments, the proposed method is shown to be faster than both the backprojection and the Norton-Linzer methods. Further, the reconstructed images using the proposed methodology were of similar quality to the Norton-Linzer method and were better than the approximate backprojection method.

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Section: A Wavefield Decompositionmentioning

confidence: 99%

Section: Spherical Fourier Bessel Expansion Of Spatial Distributionmentioning

confidence: 99%

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Frequency-radial duality based photoacoustic image reconstruction

Salehin

Abhayapala

2012

The Journal of the Acoustical Society of America

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“…Kompis et al proposed a method to locate lung sound and derive an acoustic image [10]. Salehin et al used eigen-basis decomposition to locate lung sound with a circular array of sensors [11]. McKee and Goubran compared an energy-based model (identifying the location of maximum power) with a TOA model for sound localization in the human thorax [12].…”

Section: Introductionmentioning

confidence: 99%

Locating stridor caused by tumor compression by using a multichannel electronic stethoscope: a case report

Hsu

How

Huang

et al. 2020

J Clin Monit Comput

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A 67-year-old male patient with chronic obstructive pulmonary disease was admitted to a hospital in northern Taiwan for progressive dyspnea and productive cough with an enlarged left upper lobe tumor (5.3 × 6.8 × 3.9 cm 3 ). Previous chest auscultation on outpatient visits had yielded diffuse wheezes. A localized stridor (fundamental frequency of 125 Hz) was captured using a multichannel electronic stethoscope comprising four microelectromechanical system microphones. An energy-based localization algorithm was used to successfully locate the sound source of the stridor caused by tumor compression. The results of the algorithm were compatible with the findings obtained from computed tomography and bronchoscopy (mean radius = 9.40 mm and radial standard deviation = 14.97 mm). We demonstrated a potential diagnostic aid for pulmonary diseases through sound-source localization technology based on respiratory monitoring. The proposed technique can facilitate detection when advanced imaging tools are not immediately available. Continuing effort on the development of more precise estimation is warranted.

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“…15 microphones for each of the selected zones are suggested. 12 Calibration Since multiple measurements are needed simultaneously to provide active feedback of the reproduced soundfield, a microphone gain calibration procedure must be pre-conducted. We can first select a loudspeaker with normal functionality.…”

Section: Methodsmentioning

confidence: 99%

Spatial Multizone Soundfield Reproduction Design

Jin¹

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<p>It is desirable for people sharing a physical space to access different multimedia information streams simultaneously. For a good user experience, the interference of the different streams should be held to a minimum. This is straightforward for the video component but currently difficult for the audio sound component. Spatial multizone soundfield reproduction, which aims to provide an individual sound environment to each of a set of listeners without the use of physical isolation or headphones, has drawn significant attention of researchers in recent years. The realization of multizone soundfield reproduction is a conceptually challenging problem as currently most of the soundfield reproduction techniques concentrate on a single zone. This thesis considers the theory and design of a multizone soundfield reproduction system using arrays of loudspeakers in given complex environments. We first introduce a novel method for spatial multizone soundfield reproduction based on describing the desired multizone soundfield as an orthogonal expansion of formulated basis functions over the desired reproduction region. This provides the theoretical basis of both 2-D (height invariant) and 3-D soundfield reproduction for this work. We then extend the reproduction of the multizone soundfield over the desired region to reverberant environments, which is based on the identification of the acoustic transfer function (ATF) from the loudspeaker over the desired reproduction region using sparse methods. The simulation results confirm that the method leads to a significantly reduced number of required microphones for an accurate multizone sound reproduction compared with the state of the art, while it also facilitates the reproduction over a wide frequency range. In addition, we focus on the improvements of the proposed multizone reproduction system with regard to practical implementation. The so-called 2.5D multizone oundfield reproduction is considered to accurately reproduce the desired multizone soundfield over a selected 2-D plane at the height approximately level with the listener’s ears using a single array of loudspeakers with 3-D reverberant settings. Then, we propose an adaptive reverberation cancelation method for the multizone soundfield reproduction within the desired region and simplify the prior soundfield measurement process. Simulation results suggest that the proposed method provides a faster convergence rate than the comparative approaches under the same hardware provision. Finally, we conduct the real-world implementation based on the proposed theoretical work. The experimental results show that we can achieve a very noticeable acoustic energy contrast between the signals recorded in the bright zone and the quiet zone, especially for the system implementation with reverberation equalization.</p>

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Localizing Lung Sounds: Eigen Basis Decomposition for Localizing Sources Within a Circular Array of Sensors

Cited by 6 publications

References 35 publications

Frequency-radial duality based photoacoustic image reconstruction

Frequency-radial duality based photoacoustic image reconstruction

Locating stridor caused by tumor compression by using a multichannel electronic stethoscope: a case report

Spatial Multizone Soundfield Reproduction Design

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