• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

Jun 1977

Volume 61, Issue S1, pp. S1-S96

Return to All Sections
back to top
RSS Feeds
back to top Session B. Physiological Acoustics I: Acoustical Properties of the Ear
Contributed Papers
FREE

Cochlear distortion‐products: effects of altering the organ of Corti (A)

J. H. Siegel, D. O. Kim, and C. E. Molnar

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S2-S2 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
We have extended the cat studies of Kim and Molnar [Neuroscience Abstracts Vol. II, 1976] to the chinchilla with normal or altered organ of Corti. As in the cat, propagated distortion‐products (f2−f1) and (2f1−f2) are strongly present in responses of normal chinchilla cochlear‐nerve fibers. Exposure of chinchillas to a 4 kHz octave‐band noise at 108 dB SPL rms for two hours produced destruction of the organ of Corti in the basal two‐thirds of the cochlea. Two‐tone pairs with f1=3680 Hz and f2=4000 Hz, corresponding to the damaged region, produced no measurable propagated distortion‐products; two‐tone pairs with lower frequencies corresponding to the undamaged region produced large propagated distortion‐products. In normal chinchillas, brief (1–2 min) exposure to an 80–90 dB SPL single‐frequency fatiguing‐tone, similar in frequency to the two‐tone pairs, led to a temporary reduction, by more than half, of the amplitude of the propagated distortion‐products; recovery was complete in a few minutes. We conclude: (1) Propagated distortion‐products are generated in the cochlear region where both primary components are large, and then mechanically propagated apicalward like externally applied single tones; (2) even delicate and reversible alterations of the organ of Corti can affect the strongly‐nonlinear behavior of the motion of the cochlear partition. [Work supported by NIH Grants NS07498, RR00396, NS07057, and NS00162.]
FREE

Cochlear‐distortion products: inconsistency with linear motion of the cochlear partition (A)

D. O. Kim, J. H. Siegel, and C. E. Molnar

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S2-S3 (1977); (2 pages)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Under two‐tone stimulation at frequencies f1 and f2 (f1<f2), the phase‐locked response of a cochlear nerve fiber is composed predominantly of distortion‐products (f2−f1) or (2f1−f2) when these distortion frequencies are near the characteristic frequency of the nerve fiber. We have concluded (H1) that the distortion‐product is generated in a more basal region and propagated apically to the characteristic place of the distortion frequency. An alternative hypothesis (H2) postulates that the distortion‐product is generated locally near the characteristic place of the distortion frequency, and that a “second filter” passes the distortion frequency but blocks frequencies f1 and f2. With f1=3680 Hz and f2=4000 Hz, at 50 dB SPL, we have found strong (f2−f1) from fibers with characteristic frequencies near 320 Hz. In noise‐damaged cochleas [Siegel et al., Abs. No. B1], where histological and physiological examinations show damage in the basal region but no damage in the 320‐Hz region, interpretation of the absence of the (f2−f1) response in accordance with H2 would require that (1) in normal cochleas, the stimulus frequencies f1 and f2 must propagate to the 320‐Hz region; and (2) noise damage to the organ of Corti in the basal region must interfere with this propagation f1 and f2 to the 320‐Hz region. Accepted theories of cochlear mechanics support the propagation of distortion‐products as required by H1 but do not support the above two requirements needed for H2. [Work supported by NIH Grants NS07498, NS00162, RR00396, and NS07057.]
FREE

Acoustic properties of the interaural pathway in the chicken (A)

J. J. Rosowski

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S3-S3 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The acoustic transmission properties of the avian interaural pathway were measured in the chicken with a sound probe placed within the middle ear. Ten chickens, 3–9 days old, were anesthetized, both external meati were surgically excised, the animal was placed in a head holder, and sound tubes with associated probe microphones were sealed over the right and left tympanic rings. The left middle ear was opened, and a 1‐mm‐diam sound probe was placed in the middle ear. The ear was then resealed. Continuous pure tone stimuli of approximately 110 dB SPL and of various frequencies was presented first to one ear and then to the other. With each stimulus presentation SPL was measured at three places: the stimulated external ear, the opposite external ear, and in the middle ear. A reduction in SPL of 25–30 dB was noted in the left middle ear regardless of whether the left or right external ear was stimulated. These observations suggest that the interaural pathway imposes no attenuation on transmitted sound at frequencies within the audible range of the chicken. The importance of the interaural pathway in avian hearing has yet to be determined. [Work supported by NSF.]
FREE

Relationship between loudness discomfort level and the acoustic reflex threshold for normal and sensorineural ears (A)

H. L. McLeod and H. J. Greenberg

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S3-S3 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The relationship between loudness discomfort level (LDL) and the acoustic reflex threshold (ART) was determined by comparing the ART to LDL obtained by the psychophysical method of constant stimuli. Prerecorded, randomly selected stimuli of 1000 Hz, 2000 Hz, and a multitalker speech noise were presented to normal and sensorineural hearing‐impaired listeners. Both LDL and ART were found to be significantly higher for the hearing‐impaired group. In addition, LDL for the hearing‐impaired group consistently fell below the ART. Significant differences were shown to exist between mean LDL and ART thresholds. However, contrary to previous research [A. Olsen and N. Hipskind, J. Aud. Res. 13, 71–76 (1973)] a multiple regression analysis indicated highly significant correlations between LDL and ART. The ability of each dependent variable to predict the presence or absence of a hearing loss is included with a discussion of the dangers involved in using ART data to predict the LDL.
FREE

Decay of the acoustic reflex during steady‐state and intermittent noise exposures (A)

R. Hétu and P. U. Careau

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S3-S3 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Acoustic‐reflex activity was continuously monitored by measuring change in the acoustic impedance at the eardrum for seven normal‐hearing young adults under three temporal patterns of exposure to a broadband noise: one steady‐state condition of 16 min duration at 105 dBA and two intermittent conditions of 32 min total duration with sound levels alternating between 105 dBA and quiet every 1 or 4 min, depending upon the condition. It was found that after 16 min of actual noise exposure, acoustic‐reflex response decreased to 40% of initial magnitude under the steady‐state and the 4‐min on—off conditions. Under both intermittent conditions, progressive decrease of on‐response following onset of successive noise bursts showed that quiet periods allowed only partial restoration of initial reflex excitability. Under the 4‐min on–off condition, it was observed that the contractile strength of the middle ear muscles recovered to the level observed for equivalent exposure times under the 1‐min on—off condition; however, during the third minute of the, 4‐min bursts, it decreased to the level observed under the steady‐state noise condition for equivalent cumulative exposure time.
FREE

Influence of alcohol on the acoustic reflex and temporary threshold shift (A)

M. S. Robinette and R. H. Brey

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S3-S3 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Blood alcohol levels between 0.09% and 0.15% were found to reduce the protective action of the acoustic reflex in five normal hearing human subjects. Specifically, acoustic reflex thresholds were raised, reflex magnitude decreased, and TTS increased under alcohol conditions. Stimuli consisted of a narrowband noise (500–1000 Hz) and a 500‐Hz pure tone. Measurements were made at blood alcohol concentrations from 0.05% to 0.15%. TTS at 1000 Hz was determined three minutes following a 10‐min exposure of narrowband noise at −5, +5, and +20 dB relative to the subject's pre‐alcohol acoustic reflex threshold. [Work supported by NIH.]
FREE

On the input acoustic admittance of the human middle‐ear (A)

W. M. Rabinowitz

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S3-S3 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
A method for obtaining the acoustic admittance (or impedance) at the eardrum of normal human ears is discussed. Its validity is demonstrated for frequencies up to 4 kHz. Special attention is given to estimating the earcanal space between the eardrum and the tip of the electroacoustic probe hermetically sealed in the earcanal; admittance measurements with earcanal static pressures of +40 and −40 cm H2O (re ambient) are used. However, in contrast to the usual assumption applied in clinical measurements, we do not assume that these static pressures reduce the (middle‐ear) admittance at the eardrum to zero. Results are reported for four subjects. Below 500 Hz, the eardrum admittance is compliance dominated. From 1 to 4 kHz, the resistive component of the eardrum impedance exceeds the reactive component. Furthermore, a local increase in eardrum resistance is observed near 2 kHz; this may reflect the influence of the middle‐ear cavity resonance [J.J. Zwislocki, J. Acoust. Soc. Am. 34, 1514–1523 (1962)]. Implications of the results for earphone couplers are discussed. [Work supported by NIH.]
FREE

Growth of right ear advantage following callosal section in an adolescent (A)

M. L. Lenhardt

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S3-S3 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Material previously reported to the Society (92nd meeting, Abs. No. WW3) described a thirteen year old boy's performance prior to and post surgical section of his corpus callosum on dichotic CVs (provided by Kresge, LSU). Pre‐operatively, no ear advantage was observed. After section, a clear right ear superiority emerged. Correct performance almost doubled for the right ear, whereas the left ear performance dropped to chance level. The error pattern did not vary after surgery. Prior to section only a few “double corrects” were reported for dichotic stimulation. This may have been influenced by the anxiety of the upcoming surgery. Initial post surgical testing revealed no “double corrects.” Present data, approximately 10 months later, revealed an increase in “double corrects,” as well as in ear advantage and performance. Data on time‐staggered CVs suggested a changing information processing situation. Implications of the data will be discussed.
FREE

Occluded ear simulators (A)

M. D. Burkhard and J. C. Zuercher

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S4-S4 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
With the aid of a computer program, accurate models of acoustical elements were used to study and investigate both the Zwislocki‐type ear simulators and proposed alternative designs. An occluded ear simulator is the part that remains adjacent to the eardrum when an earmold is inserted into the ear and, in most designs, contains the acoustic networks that establish an equivalent eardrum impedance. The designs were optimized using parametric methods. This led to a better understanding of Zwislocki‐type four‐resonator structures for simulating real ear eardrum impedance and also to the design of a new two‐resonator construction. The agreement between the ear simulator designs (both theoretical and experimental) with available data on ears is discussed. Tentative electrical analog values of constants for the resonators of the new design are as follows: Resonator 1: resistance 1030 ω, compliance 0.13 μF, and inertance 0.16 H. Resonator 2: resistance 300 ω, compliance 0.34 μF, and inertance 0. 0043 H. The canal portion of the occluded ear simulator is a cylinder 12.7 mm long and 7.5 mm in diameter. The external diameter is 19.4 mm. The design avoids placement of resistance elements in the canal simulation portion which would prevent its use for experiments that might require access to this region.
FREE

External and middle ears, the determinants of the auditory threshold curves (A)

S. M. Khanna and J. Tenndorf

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S4-S4 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The pressure transformation ratio of the cat's ear under auditory free‐field conditions was calculated from Nedzelnitzky's data [pressure in scala vestibuli (sc. v.) for a constant SPL at the tympanic membrane] with appropriate corrections applied for his open bulla and the tympanic membrane reference. For a constant SPL at the pinna, the pressure in sc. v. followed a curve identical to an inverted plot of the cat's free‐field threshold. Therefore, when expressed in terms of threshold SPLs at the pinna, the pressure in sc. v. became independent of frequency, its absolute value being 0. 003 dyn/cm2. These results demonstrate the importance of the acoustic properties of ear canal and pinna. They also suggest that the free‐field threshold curve is mainly determined by properties of the external and middle ears, including the inner‐ear input impedance. The power entering the inner ear at threshold was calculated from cat impedance data of Lynch and Peake. Its value is about 10−18 W for frequencies between 50 and 7000 Hz. [Supported by NIH grants.]
FREE

Dual processes for loudness (A)

W. H. Atkinson

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S4-S4 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
A body of anatomical, electrophysiological, psychophysical, and behavioral research supports the proposition that there is a division in audition similar to the rod/cone dichotomy in vision. Evidence will be presented for the presence of discrete processes for low and high intensity sounds. Both can be identified in electrophysiological measurements at all levels of the auditory nervous system. Both processes can also be discerned in magnitude estimates of loudness. If subjective loudness is plotted as a function of the cube root of sound pressure, the curve consists of two linear sections with a discontinuity of slope at approximately 65 dB SPL. Both segments are present for frequencies up to at least 3 kHz. Linearity is preserved in the presence of a masking noise but the variation in slope and intercept constants suggests the operation of different mechanisms of masking for each process.
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close