Estimation of sound pressure level exposures from sound power level measurements of powered hand-tools

The aerodynamic generated noise in the supersonic wind tunnel during operation at Ryerson University has exceeded the threshold of hearing damage. An acoustic silencer was to be designed and added to the wind tunnel to reduce the noise level. The main sources of noise generated from the wind tunnel with the silencer were identified to be located at the convergent divergent nozzle and the turbulent region downstream of the shock wave at the diffuser with the maximum acoustic power level of the entire wind tunnel at 161.09 dB. The designed silencer provided an overall sound pressure level reduction of 21.41 db which was considered as acceptable. Refinement to the mesh size and changes to the geometry of the mixing chamber was suggested for a more accurate result in noise output as well as flow conditions would match up to the physical flow. Additional acoustic treatment should be applied to the wind tunnel to further reduce sound pressure level since the noise level still exceeded the threshold of hearing loss.

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Gyro Rock Crusher and Asphalt Plant Sound Power Levels

ASME 2012 Noise Control and Acoustics Division Conference ◽

10.1115/ncad2012-1502 ◽

2012 ◽

Author(s):

Henry A. Scarton ◽

Kyle R. Wilt

Keyword(s):

Sound Pressure Level ◽

Sound Pressure ◽

Low Frequency ◽

Pressure Level ◽

Sound Power ◽

Far Field ◽

Atmospheric Attenuation ◽

Frequency Sound ◽

Sound Pressure Levels ◽

Rock Crusher

Sound power levels including the distribution into octaves from a large 149 kW (200 horsepower) gyro rock crusher and separate asphalt plant are presented. These NIST-traceable data are needed for estimating sound pressure levels at large distances (such as occurs on adjoining property to a quarry) where atmospheric attenuation may be significant for the higher frequencies. Included are examples of the computed A-weighted sound pressure levels at a distance from the source, including atmospheric attenuation. Substantial low-frequency sound power levels are noted which are greatly reduced in the far-field A-weighted sound pressure level calculations.

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Evaluation and Improvement of the Sound Quality of a Diesel Engine Based on Tests and Simulations

Energies ◽

10.3390/en13040777 ◽

2020 ◽

Vol 13 (4) ◽

pp. 777 ◽

Cited By ~ 1

Author(s):

Zhengwei Yang ◽

Huihua Feng ◽

Bingjie Ma ◽

Ammar Abdualrahim Alnor Khalifa

Keyword(s):

Diesel Engine ◽

Sound Pressure Level ◽

Sound Pressure ◽

Subjective Evaluation ◽

Sound Field ◽

Sound Quality ◽

Pressure Level ◽

Sound Power ◽

Improvement Strategy ◽

Radiated Sound

Traditional acoustic evaluation of a diesel engine generally uses the A-weighted sound pressure level (AWSPL) and radiated sound power to assess the noise of an engine prototype present in an experiment. However, this cannot accurately and comprehensively reflect the auditory senses of human subjects during the simulation stage. To overcome such shortage, the Moore–Glasberg loudness and sharpness approach is applied to evaluate and improve the sound quality (SQ) of a 16 V-type marine diesel engine, and synthesizing noise audio files. Through finite element (FE) simulations, the modes of the engine’s block and the average vibrational velocity of the entire engine surface were calculated and compared with the test results. By further applying an automatically matched layer (AML) approach, the engine-radiated sound pressure level (SPL) and sound power contributions of all engine parts were obtained. By analyzing the Moore–Glasberg loudness and sharpness characteristics of three critical sound field points, an improvement strategy of the oil sump was then proposed. After improvement, both the loudness and sharpness decreased significantly. To verify the objective SQ evaluation results, ten noise audio clips of the diesel engine were then synthesized and tested. The subjective evaluation results were in accordance with the simulated analysis. Therefore, the proposed approach to analyze and improve the SQ of a diesel engine is reliable and effective.

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