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.

Managing an "Own Voice" Problem That Has an Amplifier Origin

2005 ◽  
Vol 16 (10) ◽  
pp. 781-788 ◽  
Author(s):  
Francis Kuk
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Hearing Aid ◽  
Low Frequency ◽  
Pressure Level ◽  
Fine Tuning ◽  
Ear Canal ◽  
Frequency Sound ◽  
Tuning Process ◽  
Voice Problem

The complaint from hearing aid wearers of hollowness in the sound of their voice is typically associated with excessive low-frequency sound pressure level (SPL) in the ear canal. Increasing the vent diameter and/or reducing the gain in the low frequency would typically minimize this complaint. This paper reports on a case where the origin of hollowness was insufficient low-frequency gain compared to a previous hearing aid fitting. It describes the systematic process that was followed in uncovering the origin of the patient's hollowness complaint. Clinicians might follow a similar objective approach in their fine-tuning process to resolve wearer complaints.

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.

Control of hearing-aid saturated sound pressure level by frequency-shaped output compression limiting

1999 ◽  
Vol 28 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Hugh J. McDermott ◽  
Michelle R. Dean ◽  
Harvey Dillon
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Hearing Aid ◽  
Pressure Level

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.

scholarly journals Study on acoustic source characteristics of distributed optical fiber acoustic wave monitoring buried natural gas pipeline leakage

2021 ◽  
Vol 252 ◽  
pp. 03043
Author(s):  
Chun Wang ◽  
Zan Wang ◽  
Jia Zhang ◽  
Kelong Yang
Keyword(s):  
Natural Gas ◽  
Acoustic Wave ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Low Frequency ◽  
Pressure Level ◽  
Gas Pipeline ◽  
Sound Waves ◽  
Natural Gas Pipeline ◽  
Distributed Optical Fiber

In order to study the leakage of buried natural gas pipeline caused serious environmental pollution and human casualties, the acoustic propagation characteristics of buried natural gas pipeline leakage monitored by distributed optical fiber were studied. At present, the research on the leakage of buried pipeline mainly focuses on the propagation of sound waves along the pipe wall, while the study on the propagation of sound waves in the soil is still lacking. The acoustic attenuation of acoustic wave propagation in soil by the size of leakage hole and leakage pressure is studied, and the evolution process of acoustic wave in soil is revealed. The conclusion is that the acoustic source of buried natural gas pipeline leakage belongs to broadband noise, and the acoustic energy of leakage is prominent in the low frequency band of 15kHz. The lower frequency, the higher sound pressure level. The oscillation of the sound pressure level attenuates with the increase of frequency. Fiber optic monitoring of buried natural gas pipeline leakage early warning provides theoretical support for the conclusion. The sound pressure level in low frequency band is of great significance for buried pipeline leakage monitoring.

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