A comparison of two methods for estimating sound pressure level at the tympanic membrane at high frequencies for hearing aids.

2010 ◽  
Vol 127 (3) ◽  
pp. 1868-1868
Author(s):  
Tao Zhang ◽  
Karrie Recker ◽  
Janice LoPresti ◽  
Matt Kleffner ◽  
William Ryan
Keyword(s):  
Tympanic Membrane ◽  
Sound Pressure Level ◽  
Hearing Aids ◽  
Sound Pressure ◽  
Pressure Level ◽  
High Frequencies

Using Average Correction Factors to Improve the Estimated Sound Pressure Level Near the Tympanic Membrane

2012 ◽  
Vol 23 (09) ◽  
pp. 733-750
Author(s):  
Karrie LaRae Recker ◽  
Tao Zhang ◽  
Weili Lin
Keyword(s):  
Tympanic Membrane ◽  
Sound Pressure Level ◽  
Hearing Aids ◽  
Best Practice ◽  
Sound Pressure ◽  
Pressure Level ◽  
Correction Factors ◽  
Ear Canal ◽  
Frequency Components ◽  
Ear Canals

Background: Sound pressure-based real ear measurements are considered best practice for ensuring audibility among individuals fitting hearing aids. The accuracy of current methods is generally considered clinically acceptable for frequencies up to about 4 kHz. Recent interest in the potential benefits of higher frequencies has brought about a need for an improved, and clinically feasible, method of ensuring audibility for higher frequencies. Purpose: To determine whether (and the extent to which) average correction factors could be used to improve the estimated high-frequency sound pressure level (SPL) near the tympanic membrane (TM). Research Design: For each participant, real ear measurements were made along the ear canal, at 2–16 mm from the TM, in 2-mm increments. Custom in-ear monitors were used to present a stimulus with frequency components up to 16 kHz. Study Sample: Twenty adults with normal middle-ear function participated in this study. Intervention: Two methods of creating and implementing correction factors were tested. Data Collection and Analysis: For Method 1, correction factors were generated by normalizing all of the measured responses along the ear canal to the 2-mm response. From each normalized response, the frequency of the pressure minimum was determined. This frequency was used to estimate the distance to the TM, based on the ¼ wavelength of that frequency. All of the normalized responses with similar estimated distances to the TM were grouped and averaged. The inverse of these responses served as correction factors. To apply the correction factors, the only required information was the frequency of the pressure minimum. Method 2 attempted to, at least partially, account for individual differences in TM impedance, by taking into consideration the frequency and the width of the pressure minimum. Because of the strong correlation between a pressure minimum's width and depth, this method effectively resulted in a group of average normalized responses with different pressure-minimum depths. The inverse of these responses served as correction factors. To apply the correction factors, it was necessary to know both the frequency and the width of the pressure minimum. For both methods, the correction factors were generated using measurements from one group of ten individuals and verified using measurements from a second group of ten individuals. Results: Applying the correction factors resulted in significant improvements in the estimated SPL near the TM for both methods. Method 2 had the best accuracy. For frequencies up to 10 kHz, 95% of measurements had <8 dB of error, which is comparable to the accuracy of real ear measurement methods that are currently used clinically below 4 kHz. Conclusions: Average correction factors can be successfully applied to measurements made along the ear canals of otologically healthy adults, to improve the accuracy of the estimated SPL near the TM in the high frequencies. Further testing is necessary to determine whether these correction factors are appropriate for pediatrics or individuals with conductive hearing losses.

R-weighting provides better estimation for rat hearing sensitivity

2000 ◽  
Vol 34 (2) ◽  
pp. 136-144 ◽  
Author(s):  
E. Böjrk ◽  
T. Nevalainen ◽  
M. Hakumäki ◽  
H.-M. Voipio
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Level ◽  
Pressure Level ◽  
Sound Studies ◽  
Response Curves ◽  
Acoustic Environment ◽  
High Frequencies ◽  
Hearing Sensitivity ◽  
Sound Levels

Since sounds may induce physiological and behavioural changes in animals, it is necessary to assess and define the acoustic environment in laboratory animal facilities. Sound studies usually express sound levels as unweighted linear sound pressure levels. However, because a linear scale does not take account of hearing sensitivity-which may differ widely both between and within species at various frequencies-the results may be spurious. In this study a novel sound pressure level weighting for rats, R-weighting, was calculated according to a rat's hearing sensitivity. The sound level of a white noise signal was assessed using R-weighting, with H-weighting tailored for humans, A-weighting and linear sound pressure level combined with the response curves of two different loudspeakers. The sound signal resulted in different sound levels depending on the weighting and the type of loudspeaker. With a tweeter speaker reproducing sounds at high frequencies audible to a rat, R- and A-weightings gave similar results, but the H-weighted sound levels were lower. With a middle-range loudspeaker, unable to reproduce high frequencies, R-weighted sound showed the lowest sound levels. In conclusion, without a correct weighting system and proper equipment, the final sound level of an exposure stimulus can differ by several decibels from that intended. To achieve reliable and comparable results, standardization of sound experiments and assessment of the environment in animal facilities is a necessity. Hence, the use of appropriate species-specific sound pressure level weighting is essential. R-weighting for rats in sound studies is recommended.

A Calibration Procedure for the Assessment of Thresholds above 8000 Hz

1982 ◽  
Vol 25 (4) ◽  
pp. 618-623 ◽  
Author(s):  
Patricia G. Stelmacttowicz ◽  
Michael P. Gorga ◽  
John K. Cullen
Keyword(s):  
Frequency Response ◽  
Flat Plate ◽  
Tympanic Membrane ◽  
Sound Pressure Level ◽  
Potential Application ◽  
Sound Pressure ◽  
Calibration Procedure ◽  
Pressure Level ◽  
Frequency Dependent ◽  
Tympanic Membranes

A technique is described to estimate the sound pressure level developed by a broad frequency response transducer at the tympanic membrane. Real-ear probe tube measurements near the tympanic membranes of 10 subjects were used to obtain frequency-dependent correction values for a custom-designed flat-plate coupler. These latter measures can be used tot routine calibration of the transducer. Audiometric thresholds from 250 to 16000 Hz were obtained on 14 children (5–18 years).Threshold estimates were found to be comparable to previouslv reported values. Potential application and limitations of this technique are discussed.

Hearing Loss, Speech, and Hearing Aids

1993 ◽  
Vol 36 (2) ◽  
pp. 228-244 ◽  
Author(s):  
Dianne J. Van Tasell
Keyword(s):  
Hearing Loss ◽  
Sound Pressure Level ◽  
Hearing Aids ◽  
Speech Signal ◽  
Sound Pressure ◽  
Current Knowledge ◽  
Current Data ◽  
Pressure Level ◽  
Impaired Hearing ◽  
Moderate Hearing Loss

Modern hearing aids permit adjustment of a number of electroacoustic parameters, among them frequency response, saturation sound pressure level, and various aspects of compression. Relatively little is known, however, about how the electroacoustic characteristics of hearing aids affect the information-bearing properties of speech. Even less is known about how hearing aids might alleviate or exacerbate the effects of impaired hearing. This article reviews current knowledge in three areas: (a) characteristics of mild/moderate hearing loss, (b) informationbearing aspects of speech, and (c) the relation between electroacoustic characteristics of hearing aids and the speech signal. Concluding suggestions are made regarding the implications of the current data for selecting hearing-aid characteristics.

Effect of Canal Depth on Sound Pressure Level Distribution in Human Bilateral Ears

2011 ◽  
Vol 145 ◽  
pp. 63-67
Author(s):  
Jen Fang Yu ◽  
Wei De Cheng
Keyword(s):  
Sound Pressure Level ◽  
Hearing Aids ◽  
Sound Pressure ◽  
Stimulus Frequency ◽  
Pressure Level ◽  
Ear Canal ◽  
Custom Made ◽  
Different Depths ◽  
Ear Canals ◽  
The Right

This study was to measure the sound pressure level distribution by ear canal resonance in the human left and right external auditory canals (EAC). The gain for different stimulus frequencies was analyzed at four different measuring depths (0.5 cm, 1.0 cm, 1.5 cm and 2.0 cm) from the entrance of the ear canal bilaterally. Comparative evaluation showed that the gain for different stimulus frequencies at a depth of 2.0 cm was consistent with the results of Dillon’s study. In addition, the gain for the right EAC at 4000 Hz was larger than that of the left EAC by 1.2 dB at 0.5 cm, 1.8 dB at 1.0 cm, and 0.8 dB at 1.5 cm. This seems to suggest that gain at 4000 Hz is more affected by depth in the right EAC than in the left EAC. This study further found that the gain at the stimulus frequency of 4000 Hz was more affected by the depth than at 2000 Hz for the bilateral ear canals respectively. These gain differences between the right and left ears were statistically significant (p<0.05) at any of four measuring depths. The findings of this study may have an understanding of gain distribution to have implications for microphone placement of custom-made bilateral hearing aids (i.e. ITC or CIC) as these are placed at different depths within the ear canal. Keywords: Sound pressure level; Canal depth; Ear canal resonance; Real ear measurement; External auditory canal

Multichannel loudness compensation method based on segmented sound pressure level for digital hearing aids

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740059 ◽  
Author(s):  
Ruiyu Liang ◽  
Ji Xi ◽  
Yongqiang Bao
Keyword(s):  
Sound Pressure Level ◽  
Hearing Aids ◽  
Filter Bank ◽  
Sound Pressure ◽  
Pressure Level ◽  
Hearing Impaired ◽  
Compensation Method ◽  
Digital Hearing Aids ◽  
Gain Compensation ◽  
Adjacent Channels

To improve the performance of gain compensation based on three-segment sound pressure level (SPL) in hearing aids, an improved multichannel loudness compensation method based on eight-segment SPL was proposed. Firstly, the uniform cosine modulated filter bank was designed. Then, the adjacent channels which have low or gradual slopes were adaptively merged to obtain the corresponding non-uniform cosine modulated filter according to the audiogram of hearing impaired persons. Secondly, the input speech was decomposed into sub-band signals and the SPL of every sub-band signal was computed. Meanwhile, the audible SPL range from 0 dB SPL to 120 dB SPL was equally divided into eight segments. Based on these segments, a different prescription formula was designed to compute more detailed gain to compensate according to the audiogram and the computed SPL. Finally, the enhanced signal was synthesized. Objective experiments showed the decomposed signals after cosine modulated filter bank have little distortion. Objective experiments showed that the hearing aids speech perception index (HASPI) and hearing aids speech quality index (HASQI) increased 0.083 and 0.082 on average, respectively. Subjective experiments showed the proposed algorithm can effectively improve the speech recognition of six hearing impaired persons.

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