The Effects of Aging on the Magnitude of the Acoustic Reflex

1981 ◽  
Vol 24 (3) ◽  
pp. 406-414 ◽  
Author(s):  
Richard H. Wilson
Keyword(s):  
Sound Pressure ◽  
Age Groups ◽  
Sampling Technique ◽  
Pressure Level ◽  
Broadband Noise ◽  
Individual Growth ◽  
Growth Data ◽  
Ear Canal ◽  
Acoustic Reflex ◽  
The Individual

Aural acoustic-immittance (admittance and impedance) measurements during the quiescent and reflexive states were made using a computer sampling technique on 18 subjects with normal hearing in each of two age groups (< 30 years and > 50 years). Seven pure-tones (250–6000 Hz) and broadband-noise stimuli served to elicit the acoustic reflex at sound-pressure levels from 84–116 dB (tones) and 66–116 dB (noise) in 2-dB steps during ascending and descending runs. The contralateral middle-ear activity, was monitored with a 220-Hz probe by digitizing the conductance and susceptance outputs of an acoustic-admittance meter. The computer corrected for the immittance characteristics of the ear-canal volume by utilizing measurements made at an ear-canal pressure of -350 daPa and then by converting the conductance and susceptance values into admittance and impedance units. The results are reported as the immittance change between the quiescent and reflexive states as a function of both the activator sound-pressure level and the activator-pressure level above the reflex threshold. There were no significant differences between the static-immittance values for the two groups, Although acoustic-reflex thresholds for the two groups were the same in the low- to mid-frequency region (250–2000 Hz), the reflex thresholds for the > 50-years group were elevated significantly ( 8 dB) for 4000 Hz, 6000 Hz, and noise activators. In all conditions, the magnitude of the acoustic reflex was substantially smaller for the > 50-years group as compared with the < 30-years group. The variability of the reflex magnitude was large for both groups of subjects. Saturation of the individual growth functions, which was frequency dependent, occurred twice as often with the > 50-years group as with the < 30-years group. The relationship between the magnitude changes in conductance and susceptance from the quiescent to the reflexive state was the same for the two groups. Finally, the magnitude differences among the reflex-growth data were not related to differences in static immittance.

Aural Acoustic-Immittance Measurements

1981 ◽  
Vol 46 (4) ◽  
pp. 413-421 ◽  
Author(s):  
Richard H. Wilson ◽  
Janet E. Shanks ◽  
Therese M. Velde
Keyword(s):  
Sound Pressure ◽  
Broadband Noise ◽  
Intensity Level ◽  
Growth Data ◽  
Acoustic Reflex ◽  
Individual Subject ◽  
Acoustic Admittance ◽  
Sound Pressure Levels ◽  
Pure Tones ◽  
The Individual

Bilateral measurements of the aural acoustic-immittance characteristics of the middle-ear transmission systems of 48 subjects were made with an acoustic-admittance meter. The measurements, including static acoustic-immittance, acoustic-reflex thresholds, and acoustic-reflex growth functions, were made using a 220-Hz probe. The contralateral reflex data for three pure tones (500, 1000, and 2000 Hz) and for broadband noise were acquired in 2-dB steps at sound-pressure levels from 84–116 dB (tones) and 66–116 dB (noise) during ascending- and descending-intensity level runs. For all acoustic-immittance measurements, right ear and left ear comparisons were made and found not to be significantly different. The individual subject data then were expressed as the absolute differences between ears. In this manner normative inter-aural immittance differences were defined. The peak static immittance data were analyzed in terms of median inter-aural differences and upper 80% cut-off values. The 80% range for normal immittance values were smaller for a within subject versus an across subject comparison. For acoustic-reflex thresholds, a disparity between ears of >10 dB was suggested as indicative of an abnormality in the auditory mechanism. Finally, the reflex-growth data indicated mean inter-aural absolute differences that ranged to .040–.043 acoustic mmhos (300–400 acoustic ohms) at the higher reflex activator sound-pressure levels.

Factors Influencing the Acoustic-Immittance Characteristics of the Acoustic Reflex

1979 ◽  
Vol 22 (3) ◽  
pp. 480-499 ◽  
Author(s):  
Richard H. Wilson
Keyword(s):  
Middle Ear ◽  
Sound Pressure ◽  
Broadband Noise ◽  
Intensity Level ◽  
Ear Canal ◽  
Acoustic Reflex ◽  
Impedance Characteristics ◽  
Reflex Threshold ◽  
Acoustic Reflex Threshold ◽  
Tonal Stimuli

Measurements of the aural acoustic-immittance (admittance and impedance) characteristics of the middle-ear transmission system in humans during the quiescent (static) and reflexive states were made (N = 36) utilizing a signal-averaging technique. Three pure tones (750, 1000, and 2000 Hz) and broadband noise stimuli elicited the acoustic reflex in 2-dB steps at sound-pressure levels from 84–116 dB (tones) and 66–116 dB (noise) during ascending- and descending-intensity level runs. The contralateral middle-ear activity was monitored with a 220-Hz probe by digitizing the conductance and susceptance outputs of an admittance meter. A computer corrected for the ear-canal volume utilizing measurements made at ear-canal pressures of 0 and −350 daPa and then converted the conductance and susceptance values into admittance and impedance units. The results were reported in absolute and relative immittance units, including components, as a function of both stimulus sound-pressure level and intensity level above the acoustic-reflex threshold. The static immittance of the middle ear changed nonlinearly over time to lower admittance or higher impedance values. The influence of this static-immittance shift on the reflex magnitude was discussed. The largest mean reflex magnitude and the slowest rate of growth were observed with broadband noise, although eight of the 36 subjects demonstrated the largest reflex magnitude in response to one or more of the tonal stimuli. Although static-immittance values and acoustic-reflex thresholds were poorly correlated, the reflex magnitudes were proportional to static immittance. The variability of the reflex measures was similar to the variability of the static-immittance values. Finally, bi-directional changes in resistance during the reflexive state were observed and discussed.

Influence of the Acoustic Reflex on Vowel Recognition

1986 ◽  
Vol 29 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Michael Dorman ◽  
Ingrid Cedar ◽  
Maureen Hannley ◽  
Marjorie Leek ◽  
Julie Mapes Lindholm
Keyword(s):  
Auditory System ◽  
Sound Pressure ◽  
Dynamic Range ◽  
Recognition Accuracy ◽  
Pressure Level ◽  
Acoustic Reflex ◽  
The Poor ◽  
Stapedial Reflex ◽  
Vowel Recognition ◽  
High Sound

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

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.

Investigation of Cavitation Phenomena on Noise of Underwater Propeller

2017 ◽  
Author(s):  
Amir Karimi Noughabi ◽  
Morteza Bayati ◽  
Mehran Tadjfar
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Control Strategies ◽  
Noise Analysis ◽  
Pressure Level ◽  
Broadband Noise ◽  
Marine Propeller ◽  
Cavitation Noise ◽  
Radiated Noise ◽  
Thrust And Torque

Underwater propeller cavitation noise is composed of tonal blade rate noise and high frequency broadband noise. Cavitation usually increases overall sound pressure level in the various frequency ranges which depends on the type of cavitation. This research had been carry out to predict the radiated noise from a marine propeller in presence of cavitation with various cavitation types. The analysis is performed by coupling an acoustic code based on the Ffowcs Williams-Hawkings (FWH) equation to unsteady Reynolds-averaged Navier-Stokes (URANS) which able to simulate multiphase flows in rotational domains. A brief summary of numerical method used to model the cavitation around the underwater propeller are presented and the thrust and torque coefficients are validated in different flow conditions by experimental results. The radiated noise along the shaft direction and perpendicular to the shaft direction is studied on both cavitating and non-cavitating propellers. Then, to predict the radiated noise due to cavitation in marine propeller, the computed sound pressure level (SPL) for non-cavitating marine propeller is compared with the SPL for the same propeller in cavitation conditions at various cavitation number and advanced coefficients. The noise analysis helps to determine the dominant noise source of the underwater propeller in different conditions, which will provide a basis for proper noise control strategies.

Control of Vocal Loudness in Young and Old Adults

2001 ◽  
Vol 44 (2) ◽  
pp. 297-305 ◽  
Author(s):  
Kristin K. Baker ◽  
Lorraine Olson Ramig ◽  
Shimon Sapir ◽  
Erich S. Luschei ◽  
Marshall E. Smith
Keyword(s):  
Respiratory System ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Age Groups ◽  
Pressure Level ◽  
Emg Activity ◽  
Old Adults ◽  
Subglottal Pressure ◽  
Young Subjects ◽  
Laryngeal Emg

This study examined the effect of aging on respiratory and laryngeal mechanisms involved in vocal loudness control. Simultaneous measures of subglottal pressure and electromyographic (EMG) activity from the thyroarytenoid (TA), lateral cricoarytenoid (LCA), and cricothyroid (CT) muscles were investigated in young and old individuals while they attempted to phonate at three loudness levels, "soft," "comfortable," and "loud." Voice sound pressure level (SPL) and fundamental frequency (F 0 ) measures were also obtained. Across loudness conditions, subglottal pressure levels were similar for both age groups. Laryngeal EMG measures tended to be lower and more variable for old compared with young individuals. These differences were most apparent for the TA muscle. Finally, across the three loudness conditions, the old individuals generated SPLs that were lower overall than those produced by the young individuals but modulated loudness levels in a manner similar to that of the young subjects. These findings suggest that the laryngeal mechanism may be more affected than the respiratory system in these old individuals and that these changes may affect vocal loudness levels.

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.

Consistency of Electroacoustic Characteristics Across Components of FM Systems

1991 ◽  
Vol 34 (3) ◽  
pp. 628-635 ◽  
Author(s):  
Linda M. Thibodeau ◽  
Kathryn A. Saucedo
Keyword(s):  
Sound Pressure Level ◽  
High Frequency ◽  
Sound Pressure ◽  
Pressure Level ◽  
Input Noise ◽  
The Individual ◽  
Equivalent Input Noise

In the absence of national or international electroacoustic standards for the evaluation of Frequency Modulated (FM) amplification systems, it becomes important to know the variability one may expect across similar models. Evaluation of thirty FM systems of the same model obtained from three different educational sites was performed to determine the variability that may occur as a result of the receiver, lapel microphone, or neckloop. There was a range as great as 20 dB in high frequency average saturation sound pressure level and equivalent input noise across receivers, lapel microphones, and neckloops. These results highlight the need for regular electroacoustic monitoring of not only the FM transmitter and receiver, but also the individual components, such as the lapel microphone and the neckloop.

Acoustic-Reflex Growth and Loudness

1979 ◽  
Vol 22 (2) ◽  
pp. 295-310 ◽  
Author(s):  
Michael G. Block ◽  
Terry L. Wiley
Keyword(s):  
Acoustic Impedance ◽  
Dynamic Range ◽  
Broadband Noise ◽  
Reflex Response ◽  
Impedance Change ◽  
Acoustic Reflex ◽  
Growth Functions ◽  
The Mean ◽  
Standard Deviations ◽  
The Individual

Acoustic-reflex growth functions and loudness-balance judgments were obtained for three normal-hearing subjects with normal middle-ear function. The hypothesis that acoustic reflex-activating signals producing proportionately equal acoustic-impedance changes are judged equal in loudness was evaluated. The mean acoustic impedance and associated standard deviations were computed for the baseline (static) and activator (reflex) portions of each reflex event. An acoustic-impedance change exceeding two standard deviations of baseline was defined as the criterion acoustic-reflex response. Acoustic impedance was measured as a function of activator SPL for broadband noise and a 1000-Hz tone from criterion magnitude to the maximum acoustic impedance (or 120-dB SPL). This was defined as the dynamic range of reflex growth. Loudness-balance measurements were made for the 1000-Hz tone and broadband noise at SPL’s representing 30, 50, and 70% of the individual dynamic range. The data supported the hypothesis.

Temporal Resolution in Normal-Hearing and Hearing-Impaired Listeners Using Frequency-Modulated Stimuli

1992 ◽  
Vol 35 (2) ◽  
pp. 436-442 ◽  
Author(s):  
John P. Madden ◽  
Lawrence L. Feth
Keyword(s):  
Temporal Resolution ◽  
Sound Pressure ◽  
Discrimination Performance ◽  
Frequency Discrimination ◽  
Normal Hearing ◽  
Pressure Level ◽  
Hearing Impaired ◽  
The Other ◽  
The Difference ◽  
The Individual

This study compares the temporal resolution of frequency-modulated sinusoids by normal-hearing and hearing-impaired subjects in a discrimination task. One signal increased linearly by 200 Hz in 50 msec. The other was identical except that its trajectory followed a series of discrete steps. Center frequencies were 500, 1000, 2000, and 4000 Hz. As the number of steps was increased, the duration of the individual steps decreased, and the subjects’ discrimination performance monotonically decreased to chance. It was hypothesized that the listeners could not temporally resolve the trajectory of the step signals at short step durations. At equal sensation levels, and at equal sound pressure levels, temporal resolution was significantly reduced for the impaired subjects. The difference between groups was smaller in the equal sound pressure level condition. Performance was much poorer at 4000 Hz than at the other test frequencies in all conditions because of poorer frequency discrimination at that frequency.

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