Sound Pressure in Insert Earphone Couplers and Real Ears

1977 ◽  
Vol 20 (4) ◽  
pp. 799-807 ◽  
Author(s):  
M. D. Burkhard ◽  
R. M. Sachs
Keyword(s):  
Frequency Response ◽  
Experimental Verification ◽  
Cylindrical Cavity ◽  
Sound Pressure ◽  
Single Frequency ◽  
Ear Canal ◽  
Circular Symmetry ◽  
Transfer Impedance ◽  
Volume Velocity ◽  
Main Cavity

It is known that sound pressure, measured in couplers via a probe-tube microphone, often shows a pressure vs frequency response that drops sharply at a single frequency. In this study sound pressure was theoretically determined at various locations within a hard-walled cylindrical cavity, driven by a constant-volume velocity source with circular symmetry. At each location in the volume, a transfer impedance was defined as the ratio of pressure to inlet-volume velocity. In the region around the inlet, the transfer impedance passes through zero as it changes from negative to positive reactance with increasing frequency. Two hard-walled cavity examples were examined in detail (1) the main cavity of a 2-cm 3 HA-2 coupler, and (2) a cavity having dimensions approximately equal to the occluded ear canal between an earmold tip and the eardrum. Contours of constant minimum sound pressure vs frequency are given for these two cylindrical volumes with experimental verification. Implications for probe microphone calibration and measurement of sound pressure in ears are discussed.

The Occlusion Effect in Bone Conduction Hearing

1965 ◽  
Vol 8 (2) ◽  
pp. 137-148 ◽  
Author(s):  
David P. Goldstein ◽  
Claude S. Hayes
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Bone Conduction ◽  
Pressure Level ◽  
Ear Canal ◽  
Significant Difference ◽  
Threshold Measure ◽  
Level Shifts ◽  
Positive Correlations ◽  
Occlusion Effect

This experiment tested the hypothesis that the occlusion effect is accompanied by an increase in sound pressure level in the external auditory canal. Pure tone bone conduction thresholds and sound pressure levels were measured, first with the ear canal open, then with the ear canal closed, at two positions of the bone vibrator and at five frequencies in 28 normal listeners. Statistical analyses revealed a significant difference between measures at 250, 500, and 1 000 cps but not at 2 000 and 4 000 cps. Average sound pressure level shifts tended to be larger than their threshold measure counterparts. The two measures, nevertheless, yielded positive correlations.

Probe-Tube Microphone Measures of Ear-Canal Sound Pressure Levels in Infants and Children

1989 ◽  
Vol 10 (4) ◽  
pp. 254-258 ◽  
Author(s):  
Judith A. Feigin ◽  
Judy G. Kopun ◽  
Patricia G. Stelmachowicz ◽  
Michael P. Gorga
Keyword(s):  
Sound Pressure ◽  
Infants And Children ◽  
Ear Canal ◽  
Sound Pressure Levels ◽  
In Infants And Children

scholarly journals Impulse Noise: Can Hitting a Softball Harm Your Hearing?

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Korrine Cook ◽  
Samuel R. Atcherson
Keyword(s):  
Spectral Analysis ◽  
Frequency Response ◽  
Sound Pressure Level ◽  
Impulse Noise ◽  
Sound Pressure ◽  
Pressure Level ◽  
Noise Floor ◽  
Playing Field ◽  
Multiple Exposures ◽  
Amplitude Frequency Response

The purpose of this study is to identify whether or not different materials of softball bats (wooden, aluminum, and composite) are a potential risk harm to hearing when batting players strike a 12′′ core .40 softball during slow, underhand pitch typical of recreational games. Peak sound pressure level measurements and spectral analyses were conducted for three controlled softball pitches to a batting participant using each of the different bat materials in an unused outdoor playing field with regulation distances between the pitcher’s mound and batter’s box. The results revealed that highest recorded peak sound pressure level was recorded from the aluminum (124.6 dBC) bat followed by the composite (121.2 dBC) and wooden (120.0 dBC) bats. Spectral analysis revealed composite and wooden bats with similar broadly distributed amplitude-frequency response. The aluminum bat also produced a broadly distributed amplitude-frequency response, but there were also two very distinct peaks at around 1700 Hz and 2260 Hz above the noise floor that produced its ringing (or ping) sound after being struck. Impulse (transient) sounds less than 140 dBC may permit multiple exposures, and softball bats used in a recreational slow pitch may pose little to no risk to hearing.

Weak, Stochastic Temporal Correlation of Large-Scale Synaptic Input Is a Major Determinant of Neuronal Bandwidth

2000 ◽  
Vol 12 (3) ◽  
pp. 693-707 ◽  
Author(s):  
David M. Halliday
Keyword(s):  
Frequency Response ◽  
Synaptic Input ◽  
Large Scale ◽  
Temporal Correlation ◽  
Spike Trains ◽  
Major Determinant ◽  
Single Frequency ◽  
Cell Simulation ◽  
Input Spike ◽  
Sample Pair

We determine the bandwidth of a model neurone to large-scale synaptic input by assessing the frequency response between the outputs of a two-cell simulation that share a percentage of the total synaptic input. For temporally uncorrelated inputs, a large percentage of common inputs are required before the output discharges of the two cells exhibit significant correlation. In contrast, a small percentage (5%) of the total synaptic input that involves stochastic spike trains that are weakly correlated over a broad range of frequencies exert a clear influence on the output discharge of both cells over this range of frequencies. Inputs that are weakly correlated at a single frequency induce correlation between the output discharges only at the frequency of correlation. The strength of temporal correlation required is sufficiently weak that analysis of a sample pair of input spike trains could fail to reveal the presence of correlated input. Weak temporal correlation between inputs is therefore a major determinant of the transmission to the output discharge of frequencies present in the spike discharges of presynaptic inputs, and therefore of neural bandwidth.

scholarly journals Protective earphones and human hearing system response to the received sound frequency signals

2018 ◽  
Vol 37 (4) ◽  
pp. 1030-1036 ◽  
Author(s):  
Niloofar Ziayi Ghahnavieh ◽  
Siamak Pourabdian ◽  
Farhad Forouharmajd
Keyword(s):  
Hearing Loss ◽  
Noise Reduction ◽  
Sound Pressure ◽  
Pressure Sensors ◽  
Sound Level ◽  
System Response ◽  
Ear Canal ◽  
Labview Software ◽  
Negative Effect ◽  
Sound Reduction

Sound is one of the most important problems in industrial environments, and it causes hearing loss at different frequencies in the workforce. Incorrect fitting of hearing protector has a negative effect on noise reduction. The present study was conducted with the aim of determination of the effective frequencies on hearing loss and variations of the sound level in different frequencies after placing the earplug. A model of ear canal with different materials was simulated. Sound pressure sensors and earplugs were placed in both sides of the ear canal. The rates of sound reduction in octave frequency signals were calculated for the simulated canal of different materials, in different distances between the microphone and the earplug with Labview software. The results of sound simulation in octave frequency signals showed that by increasing the frequency, the rates of sound reduction in different conditions also had an increasing trend. The obtained peak rates for all the situations coincided with each other at fixed frequencies. In most cases, a noise reduction in the frequency of 4000 Hz showed a high number. The maximum sound reduction was observed at 25.5 mm at frequencies below 250 Hz, which was similar to the average of human ear canal length; so the simulated model can be used to determine the performance of the protective earphones and test them at different frequencies and sound pressure levels.

Transverse variations of sound pressure in an ear canal occluded by a hearing aid

2006 ◽  
Vol 120 (5) ◽  
pp. 3159-3159
Author(s):  
Michael R. Stinson ◽  
Gilles A. Daigle
Keyword(s):  
Sound Pressure ◽  
Hearing Aid ◽  
Ear Canal

The spatial distribution of sound pressure within the human ear canal

2005 ◽  
Vol 117 (4) ◽  
pp. 2564-2564
Author(s):  
Michael R. Stinson ◽  
Gilles A. Daigle
Keyword(s):  
Spatial Distribution ◽  
Sound Pressure ◽  
Ear Canal ◽  
Human Ear
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