Difficulties in the indirect experimental inference of the low‐frequency intrinsic acoustic attenuation in marine sediments.

2010 ◽  
Vol 128 (4) ◽  
pp. 2357-2357 ◽  
Author(s):  
Alllan D. Pierce ◽  
William M. Carey
Keyword(s):  
Marine Sediments ◽  
Low Frequency ◽  
Acoustic Attenuation ◽  
Experimental Inference

Research and Application of Special Shaped Muffler Structure

2014 ◽  
Vol 1008-1009 ◽  
pp. 1387-1392
Author(s):  
Chi Zhang ◽  
Nan Xu ◽  
Zhe Zhang ◽  
Su Shan Zhang
Keyword(s):  
Transmission Loss ◽  
Low Frequency ◽  
Aerodynamic Performance ◽  
Frequency Noise ◽  
Noise Band ◽  
Low Frequency Noise ◽  
Acoustic Attenuation ◽  
Derivatives Of

The special-shaped silencing sheet and its derivatives of folded plate and expansion muffler structure, improve the acoustic attenuation performance in low frequency. The technical difficulties how dissipative silencer can effectively control the low frequency noise, is solved, the noise band of dissipative silencer is broadened, transmission loss increases, aerodynamic performance is optimized.

Acoustic performance analysis of Helmholtz resonators with conical necks and its application

2019 ◽  
Vol 67 (3) ◽  
pp. 155-167 ◽  
Author(s):  
Haitao Liu
Keyword(s):  
Finite Element ◽  
Prediction Model ◽  
Transmission Loss ◽  
Low Frequency ◽  
Wide Band ◽  
Acoustic Properties ◽  
Frequency Range ◽  
Acoustic Attenuation ◽  
Acoustic Performance ◽  
Helmholtz Resonators

The acoustic properties of the Helmholtz resonators with conical necks, which have broad acoustic attenuation band performance in the low frequency range, are investigated in this study. In order to investigate its wide-band acoustic attenuation mechanism, three-dimensional finite element models for the Helmholtz resonators with different necks are built respectively. The acoustic performance prediction model based on the one-dimensional analytical approach with acoustic length corrections is built to calculate the transmission loss results more efficiently, and the formula for calculating the resonance frequency is also derived. Then, the prediction model and the formula are verified by finite element method and experiment, which show good agreements. As a result, the prediction model is applied to analyze the sound attenuation properties of the Helmholtz resonators with conical necks, and the results show that the acoustic attenuation bandwidth in the low frequency range is improved by increasing the taper angle of the neck. At last, the approaches for the Helmholtz resonators with conical necks are applied to design an actual middle silencer of a passenger car. The results show that the designed middle silencer performs much better than the original one, which can effectively eliminate the exhaust order noise to meet the standard of exhaust noise control. The test results fully reveal that the Helmholtz resonators with conical necks in the muffler can play a better role in eliminating exhaust order noise, and the approaches proposed in this article can effectively guide the design of Helmholtz resonators with conical necks.

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