Hasil untuk "Acoustics in engineering. Acoustical engineering"

Adam Rao, Emily Huynh, T. Royston et al.

Recent developments in sensor technology and computational analysis methods enable new strategies to measure and interpret lung acoustic signals that originate internally, such as breathing or vocal sounds, or are externally introduced, such as in chest percussion or airway insonification. A better understanding of these sounds has resulted in a new instrumentation that allows for highly accurate as well as portable options for measurement in the hospital, in the clinic, and even at home. This review outlines the instrumentation for acoustic stimulation and measurement of the lungs. We first review the fundamentals of acoustic lung signals and the pathophysiology of the diseases that these signals are used to detect. Then, we focus on different methods of measuring and creating signals that have been used in recent research for pulmonary disease diagnosis. These new methods, combined with signal processing and modeling techniques, lead to a reduction in noise and allow improved feature extraction and signal classification. We conclude by presenting the results of human subject studies taking advantage of both the instrumentation and signal processing tools to accurately diagnose common lung diseases. This paper emphasizes the active areas of research within modern lung acoustics and encourages the standardization of future work in this field.

Tiesong Deng, X. Sheng, Hongseok Jeong et al.

Abstract Solid panels with additional poro-elastic materials are widely used in engineering, mainly for sound insulation. In many cases, the panels are constructed in such a way that they can be idealised to be infinitely long and uniform in one direction, forming a so-called two-and-a-half dimensional (2.5D) structure. Although the 2.5D finite element and boundary element methods (FEM-BEM) are particularly suitable for predicting the vibro-acoustic behaviour of such structures, up to now the presence of poro-elastic media have not been adequately considered. In this paper a 2.5D FE-BE vibro-acoustic model is presented which accounts for solids, fluids and poro-elastic media. The poro-elastic media are modelled using the 2.5D FE approach based on the mixed displacement-pressure formulation of Biot's theory. The solids are also modelled using the 2.5D FE method but based on the linear theory of elasticity. The internal fluids are modelled using the 2.5D FE method as well. For a flat panel, the external fluid on both sides of the panel can be modelled using the 2.5D BE method based on the Rayleigh integral. The coupling between the various sub-models is derived in detail. The accuracy of the model is demonstrated by applying it to simple multi-layered structures for which solutions can be produced using other well-established methods. It is demonstrated that the elasticity of the solid frame of a porous medium has a great influence on the vibro-acoustics of a structure containing the porous material. The method is then applied to investigate the sound transmission loss (STL) of a typical railway vehicle floor structure. Results show that STL can be greatly improved by proper arrangement of porous material layers between the interior wooden floor and the outer extrusion; however, the load bearing supporting beams may significantly reduce the benefit of the porous material layers.

Benjamin Elizalde, Daniel C. Tompkins

COVID-19 has resulted in over 100 million infections and caused worldwide lock downs due to its high transmission rate and limited testing options. Current diagnostic tests can be expensive, limited in availability, time-intensive and require risky in-person appointments. It has been established that symptomatic COVID-19 seriously impairs normal functioning of the respiratory system, thus affecting the coughing acoustics. The 2021 DiCOVA Challenge @ INTERSPEECH was designed to find scientific and engineering insights to the question by enabling participants to analyze an acoustic dataset gathered from COVID-19 positive and non-COVID-19 individuals. In this report we describe our participation in the Challenge (Track 1). We achieved 82.37% AUC ROC on the blind test outperforming the Challenge's baseline of 69.85%.

X. Antoine, M. Darbas

Hong Zhang, R. Zhu, D. Shi et al.

Abstract The rotary enclosed acoustic cavity has three common forms, which are conical, cylindrical and spherical cavity. They are widely used in practical production and belong to the category of rotary room acoustics. Therefore, the study of their acoustic characteristics is of great engineering significance. In this paper, a unified analytical model for acoustic characteristics of rotary enclosed cavity with various impedance walls is first established. A three-dimensional (3D) modified Fourier series method is proposed to construct the admissible function of sound pressure. Specifically, the sound pressure function is invariably expressed as a 3D trigonometric series superposition, which includes the multiplication of three cosine functions and six complementary polynomials. The introduction of complementary polynomials can effectively solve the impedance acoustic wall. Based on Rayleigh-Ritz energy method, the acoustic characteristics of the unified analysis model can be obtained. The sound pressure response of the cavity under the influence of different impedance walls is further studied by placing a point sound source inside the acoustic cavity. The accuracy of the unified model is verified by comparing the present results with those obtained by finite element method (FEM) and experiment, and the effect of important parameters on the acoustic characteristics is systematically studied.

Arrays play an important role in spatio-temporal signal processing with applications spanning across multiple fields such as electromagnetic (EM), acoustics, ultrasonic and seismic processing systems. In the EM domain, antenna arrays have extensive applications in wireless communications, radar, source location and microwave imaging, where electronically-steered apertures are used for the directional enhancement (or rejection) of planar waves. In radio astronomy and experimental cosmology sparse arrays are being used where the large number of grating lobes are used in conjunction with correlation beamformers towards sampling the spatial frequencies of interest. Dense aperture arrays on the other hand use Nyquist sampled array geometries and are mostly used for time-domain beamforming and imaging. In areas of acoustic engineering, acoustic arrays are used for object localization and tracking by sound, acoustic monitoring, speech enhancement as well as recognition.

G. Wang, X. Cui, H. Feng et al.

A. Matoski, R. Ribeiro

M. Felli, M. Falchi, G. Dubbioso

S. Redonnet, G. Cunha

Song Rui-lin

Salman Sadiq, M. Sabir

Wersényi György

C. Rogers

Sessler

J. Smith

I. Busch-Vishniac, J. West

W. Bell, W. L. Meyer, B. Zinn

J. Vollmann, D. Profunser, A. Meier et al.