On the sound fields of oblate and prolate hemispheroids in infinite baffles for directivity control

2021 ◽  
Vol 150 (4) ◽  
pp. 3047-3058
Author(s):  
Tim Mellow ◽  
Leo Kärkkäinen
Keyword(s):  
Sound Fields

Predictability of Deterministic Underwater Sound Fields

1993 ◽  
Author(s):  
Michael G. Brown ◽  
Frederick D. Tappert
Keyword(s):  
Underwater Sound ◽  
Sound Fields

Measurements of Acoustic Intensity in Reactive Sound Fields

1973 ◽  
Vol 54 (1) ◽  
pp. 305-306
Author(s):  
T. J. Schultz ◽  
P. W. Smith ◽  
C. I. Malme
Keyword(s):  
Acoustic Intensity ◽  
Sound Fields

scholarly journals The coherence of reverberant sound fields

2000 ◽  
Vol 108 (1) ◽  
pp. 204-210 ◽  
Author(s):  
Finn Jacobsen ◽  
Thibaut Roisin
Keyword(s):  
Sound Fields

scholarly journals Localization of Increased Noise at Operating Speed of a Passenger Wagon

2021 ◽  
Vol 13 (2) ◽  
pp. 453
Author(s):  
Ján Ďungel ◽  
Peter Zvolenský ◽  
Juraj Grenčík ◽  
Lukáš Leštinský ◽  
Ján Krivda
Keyword(s):  
Natural Frequencies ◽  
Internal Noise ◽  
High Volume ◽  
Acoustic Properties ◽  
Normal Operation ◽  
Mode Shapes ◽  
Railway Transport ◽  
Noise Sources ◽  
Sound Fields ◽  
Real Picture

Noise generated by railway wagons in operation is produced by large numbers of noise sources. Although the railway transport is considered to be environmental friendly, especially in production of CO2 emissions, noise is one of problems that should be solved to keep the railway transport competitive and sustainable in future. In the EU, there is a strong permanent legislation pressure on interior and exterior noise reduction in railway transport. In the last years in Slovakia, besides modernization of existing passenger wagons fleet as a cheaper option of transport quality improvement, quite a number of coaches have been newly manufactured, too. The new design is usually aimed at increased speed, higher travel comfort, in which reduction of noise levels is expected. However, not always the new designs meet all expectations. Noise generation and propagation is a complex system and should be treated such from the beginning. There are possibilities to simulate the structural natural frequencies to predict vibrations and sound generated by these vibrations. However, the real picture about sound fields can be obtained only by practical measurements. Simulations of the wagon’s natural frequencies and mode shapes and measurements in real operation using a digital acoustic camera Soundcam have been done, which showed that for the calculated speeds the largest share of noise from the chassis was not radiated through the floor of the wagon, as was expected, but through the ceiling of the wagon. To improve the acoustic properties of the wagon at higher speed, it was proposed to use high-volume textile insulation in the ceiling of the wagon. The paper briefly presents modern research approaches in the search for ways to reduce internal noise in selected wagons used in normal operation on the Slovak railways.

scholarly journals Turbulence and Intense Sound Fields

1956 ◽  
Vol 28 (1) ◽  
pp. 157-157
Author(s):  
Robert H. Kraichnan
Keyword(s):  
Sound Fields
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