Experimental study of sound scattering by elastic spheroids

1997 ◽  
Vol 102 (2) ◽  
pp. 933-942 ◽  
Author(s):  
X. L. Bao ◽  
Herbert Überall ◽  
J. Niemiec
Acoustics ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 505-523
Author(s):  
Emma Arvidsson ◽  
Erling Nilsson ◽  
Delphine Bard Hagberg ◽  
Ola J. I. Karlsson

Several room acoustic parameters have to be considered in ordinary public rooms, such as offices and classrooms, in order to present the actual conditions, thus increasing demands on the acoustic treatment. The most common acoustical treatment in ordinary rooms is a suspended absorbent ceiling. Due to the non-uniform distribution of the absorbent material, the classical diffuse field assumption is not fulfilled in such cases. Further, the sound scattering effect of non-absorbing objects such as furniture are considerable in these types of rooms. Even the directional characteristic of the sound scattering objects are of importance. The sound decay curve in rooms with absorbent ceilings often demonstrate a double slope. Thus, it is not possible to use reverberation time as room parameter as a representative standalone acoustic measure. An evaluation that captures the true room acoustical conditions therefore needs supplementary parameters. The aim of this experimental study is to show how various acoustical treatments affect reverberation time T20, speech clarity C50 and sound strength G. The experiment was performed in a mock-up of a classroom. The results demonstrated how absorbers, diffusers and scattering objects influence room acoustical parameters. It is shown that to some extent the parameters can be adjusted individually by using different treatments or combination of treatments. This allows for the fine-tuning of the acoustical conditions, in order to fulfill the requirements for achieving a high-quality sound environment.


Author(s):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.


1962 ◽  
Vol 5 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Bruce Quarrington ◽  
Jerome Conway ◽  
Nathan Siegel
Keyword(s):  

1974 ◽  
Vol 126 (2) ◽  
pp. 243-248
Author(s):  
A WAKABAYASHI ◽  
T KUBO ◽  
K CHARNEY ◽  
Y NAKAMURA ◽  
J CONNOLLY

1963 ◽  
Vol 45 (3) ◽  
pp. 374-383 ◽  
Author(s):  
Donald C. McIlrath ◽  
George A. Hallenbeck ◽  
Hubert A. Allen ◽  
Charles V. Mann ◽  
Edward J. Baldes ◽  
...  
Keyword(s):  

1958 ◽  
Vol 34 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Henry D. Janowitz ◽  
Vernon A. Weinstein ◽  
Rhoda G. Shaer ◽  
James F. Cereghini ◽  
Franklin Hollander

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