scholarly journals Wind turbine low frequency and infrasound propagation and sound pressure level calculations at dwellings

2018 ◽  
Vol 144 (2) ◽  
pp. 981-996 ◽  
Author(s):  
Stephen E. Keith ◽  
Gilles A. Daigle ◽  
Michael R. Stinson
Keyword(s):  
Wind Turbine ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Low Frequency ◽  
Pressure Level

scholarly journals Wind turbine sound pressure level calculations at dwellings

2016 ◽  
Vol 139 (3) ◽  
pp. 1436-1442 ◽  
Author(s):  
Stephen E. Keith ◽  
Katya Feder ◽  
Sonia A. Voicescu ◽  
Victor Soukhovtsev ◽  
Allison Denning ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level

Gyro Rock Crusher and Asphalt Plant Sound Power Levels

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.

scholarly journals Noise-silencing technology for upright venting pipe jet noise

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879481 ◽  
Author(s):  
Enbin Liu ◽  
Shanbi Peng ◽  
Tiaowei Yang
Keyword(s):  
Natural Gas ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Low Frequency ◽  
Jet Noise ◽  
Pressure Level ◽  
Living Environment ◽  
Frequency Noise ◽  
Frequency Range ◽  
Expansion Chamber

When a natural gas transmission and distribution station performs a planned or emergency venting operation, the jet noise produced by the natural gas venting pipe can have an intensity as high as 110 dB, thereby severely affecting the production and living environment. Jet noise produced by venting pipes is a type of aerodynamic noise. This study investigates the mechanism that produces the jet noise and the radiative characteristics of jet noise using a computational fluid dynamics method that combines large eddy simulation with the Ffowcs Williams–Hawkings acoustic analogy theory. The analysis results show that the sound pressure level of jet noise is relatively high, with a maximum level of 115 dB in the low-frequency range (0–1000 Hz), and the sound pressure level is approximately the average level in the frequency range of 1000–4000 Hz. In addition, the maximum and average sound pressure levels of the noise at the same monitoring point both slightly decrease, and the frequency of the occurrence of a maximum sound pressure level decreases as the Mach number at the outlet of the venting pipe increases. An increase in the flow rate can result in a shift from low-frequency to high-frequency noise. Subsequently, this study includes a design of an expansion-chamber muffler that reduces the jet noise produced by venting pipes and an analysis of its effectiveness in reducing noise. The results show that the expansion-chamber muffler designed in this study can effectively reduce jet noise by 10–40 dB and, thus, achieve effective noise prevention and control.

Evaluation of Aerodynamic Infrasound Radiating From Upwind and Downwind HAWTs

2012 ◽  
Author(s):  
Adrian Sescu ◽  
Abdollah A. Afjeh
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Sound Pressure ◽  
Low Frequency ◽  
Pressure Level ◽  
Frequency Noise ◽  
Far Field ◽  
Acoustic Analogy ◽  
Horizontal Axis Wind Turbines ◽  
Tower Shadow

A Computational Fluid Dynamics tool is used to determine the detailed flow field developing around two-blade horizontal axis wind turbines (HAWT) in downwind and upwind configurations. The resulting flow field around the wind turbine is used to evaluate the low-frequency noise radiating to the far-field, using an acoustic analogy method. The influence of the variation of wind velocity and rotational speed of the rotor to the sound pressure level is analyzed. This paper shows that the tower shadow effect of a downwind configuration wind turbine generates higher aerodynamic infrasound when compared to a corresponding upwind configuration. For validation, a comparison between numerical results and experimental data consisting of sound pressure levels measured from a two-blade downwind configuration wind turbine is presented.

Probe-Tube Microphone Measures of Vent Effects With In-the-Canal Hearing Aid Shells

1992 ◽  
Vol 1 (2) ◽  
pp. 58-62 ◽  
Author(s):  
Andrew Stuart ◽  
Robert Stenstrom ◽  
Odilia MacDonald ◽  
Mark P. Schmidt ◽  
Gail MacLean
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Hearing Aid ◽  
Low Frequency ◽  
Pressure Level ◽  
Frequency Responses ◽  
Upward Shift

The acoustic effects of three different configurations of vented in-the-canal (ITC) hearing aid shells were investigated. Real-ear sound pressure level measures (200–2000 Hz) were obtained from unvented and vented ITC shells from 12 adult subjects. In general, with increasing vent size, an increase in the amount of low-frequency reduction and an upward shift in vent kneepoints and vent-associated resonance occurred. The use of venting may be considered clinically for low-frequency reduction in ITC hearing aid frequency responses.

Amplitude modulations increase annoyance due to wind turbine noise immission

2021 ◽  
Vol 263 (2) ◽  
pp. 4048-4057
Author(s):  
Christoph Pörschmann ◽  
Stephan Großarth ◽  
Johannes M. Arend ◽  
Sebastian Schmitter ◽  
Dirk Schreckenberg ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Current Literature ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Wind Turbine Noise ◽  
Control Location ◽  
Noise Characteristics ◽  
Study Sites

Current literature suggests that annoyance of wind turbine noise is strongly affected by amplitude modulations (AM). A survey was carried out at five German residential study sites near wind turbines with a total of about 500 residents to study the effects of AM in more detail. Annoyance, disturbances, and the perception of wind turbine noise characteristics, including AM, were assessed. For each participant, address-related exposure to rating levels of wind turbines was estimated. Further, we carried out headphone-based listening experiments with participants from three of the five study areas and with non-exposed participants from another 'control' location. In the listening experiments, perceived annoyance was rated for varying AM and for different A-weighted sound pressure levels for a total number of 79 subjects. As expected, the results show an increase in annoyance with sound pressure level. Furthermore, annoyance increased significantly with the extent of amplitude modulations. Interestingly, annoyance showed a strong rise as soon as amplitude modulations became audible in the signal and this rise was hardly affected by the sound pressure level. In our contribution, we present comparisons of the results of the survey and the listening experiments.

A Criterion for Predicting the Annoyance Due to Lower Level Low Frequency Noise

1983 ◽  
Vol 2 (4) ◽  
pp. 160-168 ◽  
Author(s):  
N. Broner ◽  
H.G. Leventhall
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Low Frequency ◽  
Threshold Effect ◽  
Pressure Level ◽  
The Other ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Estimation Task ◽  
Noise Annoyance

In a study of the annoyance due to low frequency noise, 75 subjects (consisting of 21 complainants and 54 controls) carried out a magnitude estimation task and rated the annoyance due to lower-level low frequency noise (55dB–75dB). After allowing for a threshold effect, it was found that the E-weighted sound pressure level was, in general, the best predictor of lower-level low frequency noise annoyance. However, it was not a significantly better predictor than any of the other nine noise measures considered. The widely available dB(A) noise measure was therefore suggested as a useful predictor of group annoyance due to lower-level low frequency noise.

Analysis of the Influence of Racks on High Speed Train Interior Noise Using Finite Element Method

2014 ◽  
Vol 675-677 ◽  
pp. 257-260 ◽  
Author(s):  
Di Wu ◽  
Jian Min Ge
Keyword(s):  
Finite Element ◽  
Sound Pressure Level ◽  
High Speed ◽  
Sound Pressure ◽  
Low Frequency ◽  
Sound Field ◽  
Pressure Level ◽  
High Speed Train ◽  
Fe Method ◽  
Proposed Model

In this paper, the finite element (FE) method was used for simulation of the low-frequency sound field in high speed train compartments. The proposed model was validated using experimental results. The FE models of the train compartments with and without racks were established respectively, and the sound pressure level of the standard point and sound field distribution in these two cases were compared. The results showed that the A-weighted sound pressure level of the standard point was 1.2 dB lower when there is no rack in the compartment.

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