Use of coherence and phase data between two receivers in evaluation of noise environments

✍ Scribed by A.G. Piersol

• Book ID: 104154015
• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 704 KB
• Volume: 56
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1016/s0022-460x(78)80016-9

✦ Synopsis

For certain types of noise control problems, where transducers cannot be mounted on suspected sources, valuable information can often be obtained by comparing the coherence and phase data measured between two closely spaced microphones with analytical models deduced from the physics of the problem. However, the application of such analysis techniques must be pursued with care, particularly when the measurements are made in a reverberant area. A simple illustration is presented where the acoustic field in the test section of a wind tunnel is evaluated by modelling the field as a combination of diffuse noise due to the boundary layer turbulence in the test section and propagating noise generated by the tunnel fan and possible flow disturbances outside the test section. The coherence and phase between two closely spaced microphones in the tunnel test section are predicted for various ratios of diffuse to propagating noise contributions and compared to actual measurements under several different tunnel operating conditions. The results demonstrate both the strengths and limitations of the analysis procedure.