摘要:

A simple method based on plane‐wave normal incidence is used to calculate the transmission coefficient, reflection coefficient, and absorption coefficient of a wall structure. The performance of the wall structure for enclosing the noise source is estimated by a term called “noise reduction,” which is the ratio of the sound intensity at the exterior side of the wall to the sound intensity at the same point with no enclosure present. Several structures with combinations of impervious layers, air space, and sound‐absorbing material are evaluated and used as examples to demonstrate the effect of mass, acoustical impedance, propagation constant, and arrangement of materials (impervious layer, absorbing material, and air) on the acoustical performance of the wall.

ISSN:0001-4966    

DOI:10.1121/1.1913274

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The polarization of assembled electret microphones with energetic electrons from a Cockcroft‐Walton accelerator is discussed. Electron transmission curves of metallic foils and of the dielectric films Mylar and FEP Teflon are given based on experimental measurements. Results of charging experiments on Mylar and FEP are presented which show how the optimum electron bombarding energy and beam intensity were chosen for polarization of a given microphone. The method devised to monitor microphone performance in vacuum while polarization is carried out is described. The polarization of a specific microphone is discussed to illustrate the use of the electron transmission data and the method of monitoring the microphone performance.

ISSN:0001-4966    

DOI:10.1121/1.1913275

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1913276

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1913281

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1913285

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1913287

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP