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.

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.

Acoustic-Reflex Adaptation

1984 ◽  
Vol 27 (4) ◽  
pp. 586-595 ◽  
Author(s):  
Richard H. Wilson ◽  
June K. McCullough ◽  
David J. Lilly
Keyword(s):  
Half Life ◽  
Onset Time ◽  
Life Time ◽  
Broadband Noise ◽  
Acoustic Reflex ◽  
Individual Subject ◽  
Baseline Drift ◽  
Reflex Threshold ◽  
The Individual ◽  
Life Function

Acoustic-reflex adaptation was studied in 35 subjects with normal hearing using nine pure-tone activators (250-6000 Hz) and a broadband-noise activator. The individual subject data generated by the 31-s activators presented 10 dB above the reflex threshold were digitized, corrected for baseline drift and ear Canal volume, and analyzed in terms of the acoustic-admittance change in acoustic mmhos and in terms of the percentage of maximum-reflex magnitude. Reflex adaptation increased as a function of frequency. The adaptation functions for the lower frequencies (⩽1500 Hz) were essentially linear over the 31-s activator period, whereas the functions for the higher frequencies (⩾2000 Hz) were curvilinear over the activator period. The experimental half-tile data are compared with a theoretical half-life function that was generated to estimate normal acoustic-reflex adaptation as a function of activator frequency. Finally, the means and standard deviations are reported and discussed for (a) the onset time of adaptation; (b) the half-life time, and (c) the percentage of maximum reflex magnitude at 5-s intervals from 5 to 30 s.

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.

scholarly journals Effect of Intensity Level and Speech Stimulus Type on the Vestibulo-Ocular Reflex

2019 ◽  
Vol 30 (09) ◽  
pp. 792-801 ◽  
Author(s):  
Mary Easterday ◽  
Patrick N. Plyler ◽  
James D. Lewis ◽  
Steven M. Doettl
Keyword(s):  
Repeated Measures ◽  
Vestibular Nuclei ◽  
Auditory Stimulation ◽  
Broadband Noise ◽  
Speech Stimulus ◽  
Intensity Level ◽  
Acoustic Reflex ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Acoustic Reflex Threshold

AbstractAccurate vestibulo-ocular reflex (VOR) measurement requires control of extravestibular suppressive factors such as visual fixation. Although visual fixation is the dominant suppressor and has been extensively studied, the mechanisms underlying suppression from nonvisual factors of attention and auditory stimulation are less clear. It has been postulated that the nonvisual suppression of the VOR is the result of one of two mechanisms: (1) activation of auditory reception areas excites efferent pathways to the vestibular nuclei, thus inhibiting the VOR or (2) cortical modulation of the VOR results from directed attention, which implies a nonmodality-specific process.The purpose of this research was to determine if the VOR is affected by the intensity level and/or type of speech stimulus.A repeated measures design was used. The experiment was single-blinded.Participants included 17 adults (14 females, three males) between the ages of 18–34 years who reported normal oculomotor, vestibular, neurological, and musculoskeletal function.Each participant underwent slow harmonic acceleration testing in a rotational chair. VOR gain was assessed at 0.02, 0.08, and 0.32 Hz in quiet (baseline). VOR gain was also assessed at each frequency while a forward running speech stimulus (attentional) or a backward running speech stimulus (nonattentional) was presented binaurally via insert earphones at 42, 62, and 82 dBA. The order of the conditions was randomized across participants. VOR difference gain was calculated as VOR gain in the auditory condition minus baseline VOR gain. To evaluate auditory efferent function, the medial olivocochlear reflex (MOCR) was assayed using transient-evoked otoacoustic emissions (right ear) measured in the presence and absence of broadband noise (left ear). Contralateral acoustic reflex thresholds were also assessed using a broadband noise elicitor. A three-way repeated measures analysis of variance was conducted to evaluate the effect of frequency, intensity level, and speech type on VOR difference gain. Correlations were conducted to determine if difference gain was related to the strength of the MOCR and/or to the acoustic reflex threshold.The analysis of variance indicated that VOR difference gain was not significantly affected by the intensity level or the type of speech stimulus. Correlations indicated VOR difference gain was not significantly related to the strength of the MOCR or the acoustic reflex threshold.The results were in contrast to previous research examining the effect of auditory stimulation on VOR gain as auditory stimulation did not produce VOR suppression or enhancement for most of the participants. Methodological differences between the studies may explain the discrepant results. The removal of an acoustic target from space to attend to may have prevented suppression or enhancement of the VOR. Findings support the hypothesis that VOR gain may be affected by cortical modulation through directed attention rather than due to activation of efferent pathways to the vestibular nuclei.

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.

Enhancement of Word-Recognition Performance With a Filtering Technique

1991 ◽  
Vol 34 (6) ◽  
pp. 1436-1438 ◽  
Author(s):  
Richard H. Wilson ◽  
John P. Preece ◽  
Courtney S. Crowther
Keyword(s):  
Word Recognition ◽  
Sound Pressure ◽  
Recognition Performance ◽  
Notch Filter ◽  
Normal Hearing ◽  
Broadband Noise ◽  
Female Speaker ◽  
Sound Pressure Levels ◽  
Filtering Technique ◽  
Notch Filtering

The NU No. 6 materials spoken by a female speaker were passed through a notch filter centered at 247 Hz with a 34-dB depth The filtering reduced the amplitude range within the spectrum of the materials by 10 dB that was reflected as a 7.5-vu reduction measured on a true vu meter. Thus, the notch filtering in effect changed the level calibration of the materials. Psychometric functions of the NU No. 6 materials filtered and unfiltered in 60-dB SPL broadband noise were obtained from 12 listeners with normal hearing. Although the slopes of the functions for the two conditions were the same, the functions were displaced by an average of 5 8 dB with the function for the filtered materials located at the lower sound-pressure levels.

Acoustic Reflex Growth in the Aging Adult

1980 ◽  
Vol 23 (2) ◽  
pp. 405-418 ◽  
Author(s):  
David J. Thompson ◽  
John A. Sills ◽  
Kay S. Recke ◽  
Duc M. Bui
Keyword(s):  
Growth Data ◽  
Acoustic Reflex ◽  
Reflex Pathway ◽  
Rate Of Growth ◽  
Stapedius Muscle ◽  
Acoustic Admittance ◽  
The Subject ◽  
Aging Adult ◽  
Filtered Noise ◽  
Age Range

Growth in amplitude of the acoustic reflex to filtered noise and tones of 500, 1000, and 2000 Hz was measured with an aural acoustic-admittance meter in 30 persons between the ages of 20 and 79 years. Although thresholds of the acoustic reflex did not vary significantly across the age range of the subject sample, the rate of growth in amplitude decreased linearly with increase in age decade. Given information on the aging of structures in the acoustic reflex pathway, the growth data are interpreted tentatively to mean that the contractual capacity of the stapedius muscle is diminished in older ears.

scholarly journals ESTIMATION OF NOISE POLLUTION PARAMETERS AND THEIR HEALTH EFFECTS ON BUILDING OCCUPANTS IN LAGOS STATE, NIGERIA

2021 ◽  
pp. 64-86
Author(s):  
A Adekunle ◽  
Mary Omange ◽  
Adekunle Tope ◽  
Shawon Msughter
Keyword(s):  
Sound Pressure ◽  
Muscle Tension ◽  
Noise Pollution ◽  
International Standard Organization ◽  
Health Conditions ◽  
Pollution Level ◽  
Intensity Level ◽  
Sound Sources ◽  
Lagos State ◽  
Sound Pressure Levels

Noise pollution in our environments has been discovered by researchers in recent times to contribute adversely to health conditions, social challenges and occupational efficiencies of its victims. This study considered measuring noise pollution parameters within a particular locality based on the positions of the people from their respective sound sources. The parameters measured in this study are sound pressure level ( SPL ), sound intensity level (I), power emitted ( PAV ), dose of noise (D), and noise pollution level (NPL). The devices employed for noise level measurements are dosimeters and sound level meters. A total of 15 locations within Lagos state environs where noise impacts are mostly felt by citizens were considered. The results obtained revealed that the closer the hearer to the sound sources the higher the sound pressure levels and sound intensities. Locations with the highest sound pressure levels are event centers, markets, and religious centers with average sound levels 85.9dB, 84.7dB, and 83.1dB respectively. Event centers recorded the highest noise pollution level and dose of noise while schools recorded the least. Considering the hearing thresholds according to International Standard Organization, the hearers with the highest sound pressures and intensities are likely to suffer over a long period of time from health conditions such as headache, muscle tension, anxiety, insomnia, fatigue, resentment, distraction, hearing impairment, interference with communication, drug consumption, interference with relaxation, and temporary threshold shift. It is however imperative to provide continuous awareness on different ways of curbing noise pollution and its effects in our environments.

scholarly journals Prediction of Broadband Noise from Symmetric and Cambered Airfoils

2019 ◽  
Vol 11 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Vasishta BHARGAVA
Keyword(s):  
Mach Number ◽  
Sound Pressure ◽  
Power Level ◽  
Broadband Noise ◽  
Chord Length ◽  
Trailing Edge ◽  
Aerodynamic Sound ◽  
Displacement Thickness ◽  
Sound Pressure Levels ◽  
Naca 0012

Aerodynamic sound generation and self-noise mechanisms from lifting surfaces such as airfoil involve the fields of classical acoustics and fluid mechanics. In this paper, trailing edge noise production is evaluated using empirical model for NACA 0012 and NACA 6320 airfoils. The sound pressure levels from trailing edge surface are calculated for different flow configurations. The growth of boundary layer thickness and displacement thickness, for different chord lengths and Mach numbers with varying angles of attack, is illustrated for NACA 0012. The sound pressure levels were computed numerically between 00 to 60 angles of attack and at constant chord length of 1.2m using Brookes Pope Marcolini method. The results showed a change of ~2-5dB in peak amplitude for mid frequencies region of spectrum. The effects of varying chord length and Mach number on sound pressure levels are illustrated for both airfoils. The relative velocity field for airfoils was computed using the boundary element method. The combined effect of thickness and camber on sound power level is demonstrated at a 40 angle of attack and for a Mach number of 0.191. Validation of sound pressure levels is done based on the results obtained for NACA0012 for similar flow conditions.

scholarly journals Annoyance of Audible Infrasound

1987 ◽  
Vol 6 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Henrik Møller
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Dynamic Range ◽  
Pressure Level ◽  
Frequency Range ◽  
Low Frequencies ◽  
Pure Tones ◽  
The Individual

Contours of equal annoyance were determined for pure tones in the frequency range 4 – 31.5 Hz. The curves show a narrowing of the dynamic range of the ear at low frequencies. The same pattern is seen for equal loudness curves, and the results support the theory that the annoyance of infrasound is closely related to the loudness sensation. Annoyance ratings of 1/3 octave noise did not deviate from ratings of pure tones with the same sound pressure level. Combinations of audio and infrasonic noise were in general given a rating close to or slightly above the rating of the most annoying of the individual noise conditions. For infrasound the proposed G1-weighting curve is shown to give values that correlate well with subjective annoyance rating. Values obtained with the G2-curve do not correlate as well. Low audio frequencies are not covered by the G-curves, and it is shown that these are insufficiently covered by the A-curve. Further research is needed in this area.

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