bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency selectivity mediated by inner hair cells alone
Authors: Dallos Peter , Ryan Allen
Published: October 2005

A well-recognized measure of frequency selectivity can be obtained by a tone-on-tone masking paradigm, which generates a so-called “psychophysical tuning curve” [e.g., A. M. Small Jr., J. Acoust. Soc. Am. 31, 1619–1625 (1959); E. Zwicker in Facts and Models in Hearing (Springer-Verlag, New York, 1974), pp. 132–139]. This procedure was adapted to chinchillas trained with the shock-avoidance method. In order to eliminate outer hair cells from controlled regions of the cochlea, kanamycin was administered. We have demonstrated previously that this method is suitable for producing relatively pure outer hair cell losses in the basal part of the cochlea, with the immediate psychophysical correlate of an approximately 40-dB threshold shift [A. Ryan and P. Dallos, Nature (in press, 1975)]. Measurements of the “tuning curves” both before and after kanamycin treatment indicated that (1) for maskee frequencies in the unaffected frequency region the “tuning curves” are unchanged, and (2) when the maskee is in the affected region, the segment of the “tuning curve” also within that region is simply shifted proportional to the threshold shift. The curves do not become wider. This suggests that the sharpness of tuning in the auditory system can be determined by inner hair cells, acting without significant influence by the outer hair cells. [Work supported by grants from the NINDS. We thank T. McGee and C. Sanes for their contribution to this research.]
Effect of impulse noise on the temporal integration function of the chinchilla
Authors: Hans J. , Henderson D. , Hamernik R. P.
Published: October 2005

Five monaural chinchilla were exposed to impulse noise which had previously been Shown to produce outer hair cell lesions (50 impulses, 1/min, at 155-dB 1-msec “A” duration). Pre- and post-exposure quiet thresholds were measured using a conditioned avoidance procedure. Sensitivity was measured at frequencies between 0.5 and 12 kHz using both 20- and 500-msec tones. Before exposure, thresholds were 10–12 dB poorer with the short duration tone. By 45 days post-exposure, thresholds had stabilized to a 10–15-dB shift for the 20-msec tones in the 1–3-kHz region, a 20–30-rib shift for the 500-msec tones in the 0.5–3-kHz region. The animals were sacrificed and lesions were confirmed in the middle turn or whole basal half of the cochlea. The results are consistent with previous studies of temporal integration in sensorineural damaged ears by showing marked reduction in temporal integration in the frequency range most effected by the noise exposure.
Temporary threshold shift in nonhuman primates resulting from chronic exposure to a 2-kHz octave band of noise
Authors: Scheib B. T. , Stebbins W. C. , Moody D. B.
Published: October 2005

Hearing thresholds were determined in three Old-World monkeys by the staircase method, using operant conditioning procedures with positive reinforcement. Following threshold determinations, subjects were exposed to a 90-dB-SPL band of noise (1414–2828 Hz) for 36 days. The exposure was periodically interrupted during the first 36 hours in order to measure the progression of TTS at 2.8 kHz. Complete audiograms were obtained for each subject beginning the 36th hour and every 24 hours thereafter. Initial plateaus in the 2.8-kHz TTS functions occurred between 7 and 12 hours of exposure. Secondary shifts in intitial plateaus occurred on the fifth and seventh days of exposure in two subjects, These shifts were first observed at 2 kHz and later progressed to 2.8 and 4 kHz. Secondary plateaus were approximately 10 dB higher than those initially observed. The results of this study indicate that the time to reach initial TTS plateau is similar for monkey and human subjects. The secondary TTS plateau shifts question the validity of the assumption that plateaus of the TTS function occurring during the first few days of exposure represent true asymptotes. [Research supported by grants from National Institute for Neurological Disease and Stroke and National Institute for Occupational Safety and Health.]
Peripheral specialization for analysis of Doppler-shifted echoes in the auditory system of the “CF-FM” bat, Pteronotus parnellii. I. Cochlear microphonic
Authors: Suga N. , Simmons J. A. , Jen P. H.-S.
Published: October 2005

The mustache bat (Pteronotus parnellii) emits orientation sounds which consist of long constant-frequency (CF) components followed by short frequency-modulated (FM) components. The second harmonic (61–62 kHz) of the CF component is an information-bearing element and is probably used for Doppler-shift compensation. The auditory system of this animal is sharply tuned to sounds at 61–62 kHz in terms of cochlear microphonic (CM). This sharp tuning is due to the mechanical specialization of the inner ear. Because of this specialization, CM evoked by 61–62-kHz tones slowly increases and decreases in amplitude at the onset and cessation of these stimuli. The CM after the cessation of the stimuli is called the after-response or CM-aft. The area of the inner ear tuned at 60–61 kHz shows a prominent nonlinearity and is located close to the sharply tuned area, so that CM responses to 60–61-kHz tone bursts show prominent transients at the onset and cessation of the stimuli. At the cessation, the CM first increases, then decreases in amplitude. Such a CM-aft is called the off-response or CM-off. Both the CM-on and CM-aft, are tuned at 61–62 kHz, while the CM-off is tuned at 60–61 kHz. [Supported by NSF Grant GB-40018.]
Peripheral specialization for analysis of Doppler-shifted echoes in the auditory system of the “CM-FM” bat, Pteronotus parnellii. II. Properties of peripheral auditory neurons
Authors: Suga N. , Simmons J. A. , Jen P. H.-S.
Published: October 2005

The inner ear of the mustache bat (Pteronotus parnellii) is sharply tuned to sounds at 61–62 kHz and shows a prominent nonlinearity for 60–61-kHz sounds. Because of this nonlinearity, cochlear microphonic responses show prominent transients at the onset and cessation of 60–61-kHz sounds and the N1 response appears at the onset and the cessation of these stimuli. The N1-on is tuned at 63–64 kHz and is different from the best frequency of the CM-on, 61–62 kHz. This difference is due to the properties of a sharply tuned resonator and N1. The N1-off is tuned at 60–61 kHz as the CM-off is. Single peripheral neurons sensitive to 61–62-kHz sounds have an unusually sharp tuning curve. The low-frequency and high-frequency slopes are 2500–3000 and 2500–4200 dB/octave, respectively. The Q−10-dB value is as high as 300. Neurons with a best frequency between 58 and 64 kHz show not only tonic on-responses but also off-responses which are tuned at 60–61 kHz and are apparently related to the CM-off. These off-responses are not rebounds from neural inhibition. No neurons were found which showed only off-responses preceded by suppression or inhibition of background activity. [Supported by NSF Grant GB-40018.]
Underwater sound localization of pulsed pure tones by the California sea lion
Authors: Moore P. W. , Au W. W. L.
Published: October 2005

The results of a study to determine the pulsed pure-tone sound localization capability of a California Sea Lion, Zalophus californianus in the horizontal plane are presented. The minimum audible angle (MAA) was determined as a function of frequency from 0.5 to 16 kHz in one-octave steps. The results suggested that the animal utilized time difference cues for the lower frequencies (0.5–1.0 kHz) and intensity difference cues for the higher frequencies (4.0–16.0 kHz). The MAAs for the lower frequencies were smaller than for the higher frequencies, and for the transitional frequencies (2.0–4.0 kHz) the animal experienced extreme difficulties in localizing the sound. To further investigate the effects of sound intensity difference in the localization process, an experiment using a sea lion skull with hydrophones attached close to each bulla was conducted. Intensity differences were measured with the skull directed at different azimuths in relationship to a sound source. The results of the measurements using the skull considered together with the behavioral data support the contention that the sea lion used both time and intensity cues for underwater localization.
Sonar detection of fish in the presence of sound projected into a lake
Authors: Bohls Raymond W.
Published: October 2005

The presence of fish was visually observed while conducting experiments using 20-kHz sound in a clear, freshwater lake. Information was desired relating to the effects of the projected sound in attracting or repelling fish that would normally be present beneath the test platform. A hardware system has been constructed that will upon command gate a 20-kHz sinusoid into the water to possibly influence fish in the vicinity, will detect the presence of fish within 12 ft of the source by use of a 200-kHz, 0.3-msec pulse sonar; and will logically record the results. Four hundred hours of data have shown a 38.9% occurrence of fish presence immediately after the sound was projected, and a 38.4% occurrence of a fish being present when no sounds were projected into the water, indicating that the sound had no attractive effect. Sound cycled OFF for 5 minutes and ON for 3 minutes did not cause fish to migrate between cycles. A definite correlation was observed relating the decreased occurrence of fish with rainy weather in both the presence and absence of sound.
Vocal cry analysis in dairy goats
Authors: Lenhardt M. L.
Published: October 2005

The vocal outputs of two adult twin goats and their twin off-spring indicate that capra vocal behavior can be grouped into two main call types, that is, orienting bleats and distress bleats. The former is characterized as essentially a closed velar vocalization emitted primarily through the mouth. Most of the energy is below 4 kHz with maximal peaks at 360 Hz (F0), 1250 Hz, and 2500 Hz. The distress bleat is characterized by both oral and nasal emission with energy up to 15 kHz. There is peak energy at 360 Hz (F0), 2500 Hz (primarily), 8100 Hz, and 11 000 Hz. Kid vocalizations were sampled periodically for the first six months of life. Again an orienting and distress bleat can be differentiated. Basically, the orienting bleat is characterized by energy below 5700 Hz with peak levels at F0, 700 Hz, and 3800 Hz. The distress bleat has energy up to 15 kHz with an additional peak at 8800 Hz. Fundamental frequency was found to vary with age not only in range but in contour. The maternal filial relationship will be discussed, suggesting that the mother's poor auditory ability to recognize her kid during the first days of life is a function of essentially identical vocal spectrum of kid bleats during this period.
Instrumentation for laser-excited thermoacoustic array experiments
Authors: Culbertson C. R. , Muir T. G. , Thompson L. A. , Clynch J. R.
Published: October 2005

A recent analysis by Westervelt and Larson [J. Acoust. Sec. Am. 54, 121 (1973)] predicts the synthesis of highly directive acoustic arrays through the thermalization of modulated laser light in media of relatively low optical absorptivity. A new system designed for underwater measurements on thermoacoustic arrays is described here. This system employs interchangeable ruby and neodymium glass rods to produce radiations in either the red (0. 6943 μ) or infrared (1.06 μ) spectrum, respectively. These radiations consist of a statistical distribution of wide-band transients of “spikes” grouped in a ∼1-msec burst. The burst is then modulated at frequencies of 5 to 80 kHz by means of a crossed polarizer and Pockels cell located outside the optical cavity. The modulated optical power delivered to the water is measured by an integrating photodetector calibrated by calorimetric comparison. Pulsed powers on the order of 1–10 kW are achieved. The size and divergence of the laser beam are monitored by burning paper in the beam's path. The optical attenuation of the medium is determined at each wavelength by propagation loss measurements. Nearfield criteria for thermoacoustic arrays are also presented to facilitate the optimum choice of hydrophones and hydrophone locations. [This work sponsored by the U. S. Navy office of Naval Research.]
Experiments on a laser-excited thermoacoustic array
Authors: Muir T. G. , Culbertson C. R.
Published: October 2005

The optical and acoustic fields associated with the thermalization of modulated laser light in a freshwater lake were measured in accordance with the procedures set forth in the previous paper. A single, modulated laser beam entering the water in one direction was found to generate a propagating CW pulse at the modulating frequency. An optical filter test showed this pulse to emanate from the thermal volume. The amplitude of the acoustic pulse wag directly proportional to the laser power. The acoustical pulse was generated in a “doughnut”-shaped pattern, having its maximum in a plane perpendicular to the optical axis. Beam-pattern measurements show a steep monotonic decay with increasing angle from the acoustic axis. The acoustic beamwidth was found to be proportional to the optical attenuation of the medium and inversely proportional to the acoustic frequency. The dependence of sound-pressure level on the size of the optical beam was also measured. These data support the general validity of the Westervelt-Larson theory for thermoacoustic arrays that employ laser excitation. Extrapolation of the theory indicates that highly directional sound beams could be generated in clear sea water with lasers operating in the blue-green spectrum. [This work supported by the U. S. Navy Office of Naval Research.]
Electroacoustic deep-submergence transducer
Authors: Tocquet B.
Published: October 2005

An electroacoustic deep-submergence transducer is described. It includes an enclosure of closed form containing several piezoelectric motors made of ceramics and a tail mass. Each motor is connected to the enclosure which is excited by all. The motors have no other mechanical connection able to transmit static or dynamic forces except the enclosure itself. This transducer has two resonant frequencies which are independent of the value of the static pressure prevailing on the outside of the transducer, one frequency being due to the resonance of the envelope, and the other to the resonance of the motors. Experimental results were obtained for an array of ten transducers.
Wide-band projecting transducer
Authors: Batey R. L. , Wallace R. H.
Published: October 2005

A technique for obtaining a significant increase, compared to more conventional means, in percentage bandwidth for a projecting transducer has been developed. Multiple sets of elements with each set tuned to a slightly different frequency are used to obtain the increase in bandwidth. Phase problems at mid-frequencies normally associated with multifrequency operation are solved to a satisfactory degree. An analytical study concerned with bandwidth, beam pattern, transient response, and relative per-element-sensitivity is presented. Experimental data are shown to support the analytical study.
Network theoretic analysis of transducers
Authors: Sabbagh Harold A.
Published: October 2005

Starting with the open-circuit or short-circuit electroelastic normal modes of a piezoelectric body, one can compute an equivalent electromechanical admittance matrix or hydrid parameter matrix. This matrix effectively transforms the piezoelectric body into an N-port network. One is thus able to bring to bear upon transducer problems the well-developed theory of N-port networks. We have done this for a radially polarized and tangentially polarized (segmented) ferroelectric shell. In particular, we have computed the open-circuit voltage response of the radially polarized shell (assuming it to be in a hydrophone) by utilizing the admittance matrix approach, which is based on the short-circuit normal modes, and the hybrid parameter approach, which is based on the open-circuit normal modes. A comparison of the two approaches is made. In addition, we describe an application of the theory to determining the driving-point (electrical) impedance of a projector consisting of a coaxial array of segmented shells. This is done by treating both the array of shells and the surrounding fluid medium as coupled N-port networks.
Computer methods for high-power pulsed immittance measurements
Authors: George J. D. , Green R. F.
Published: October 2005

Characterizing the input immittance of underwater sound projectors under normal operating conditions requires high-power free-field testing. Pulse techniques offer a convenient approach to effecting free-field conditions in a limited space. Existing measurement systems estimate immittance at the carrier frequency using the steady-state region of projector voltage and current pulses. In extending the measurement capability at the Underwater Sound Reference Division, Naval Research Laboratory, these projector waveforms are sampled, discrete Fourier transforms taken, and immittance estimated using on-line computer control. The Fourier transform provides, in addition to the steady-state point-by-point results, a broad-band immittance plane pictured for rapid exploration of device characteristics. The impact of sampling rate, pulse shape, and device bandwidth are examined. An additional advantage of using the complete pulse spectrum rather than the steady view is that shorter pulses that yield equivalent results can be used to extend the lower frequency limit for a given space, such as a tank. An alternate definition of impedance is examined using the ideas of real and reactive power.
College campus designed for compatible co-existence with a major airport
Authors: Randorff J. E. , Johnson J. A. , Guthrie J. E. , Ernst G. H.
Published: October 2005

The acoustical environment on a proposed junior college campus was projected, utilizing the aircraft flyover data due to the operations from a nearby major jet airport. This information formed the acoustical basis by which the architectural design considerations were influenced. Emphasis was placed upon the unique, and yet practical, manner of mixing space usage areas together with some construction material changes to create a cost-conscious facility. The architectural aesthetics, functional space planning, educational specifications, and acoustic criteria were coordinated to assure that no area requiring special consideration would be neglected. The acoustical criteria for space conditioning were formulated and the acoustical insulation criteria were given for each space usage area. Priorities in terms of space usage versus project economics were established. The design process thus was able to incorporate these priorities together with the basic architectural concepts to create a learning environment which is acoustically compatible with the aircraft noise levels impinging on the campus site. Within this design framework, the economics were balanced to insure a realistic cost based upon the projected lifetime of the campus structures.
Results of some experiments on takeoff noise in a high-velocity air-conditioning system
Authors: Sawley Roger J.
Published: October 2005

Techniques are available whereby it is possible to estimate the noise generated at a takeoff from a duct in an air-conditioning system. These techniques relate to smooth, low (on the order of 5%) turbulence level conditions in the flow. In this paper are presented the results of some experiments which suggest that the aspect ratio of the duct takeoff is important and which show, further, how turbulence control is effective as a noise control measure when the flow incident upon the take-off is excessively turbulent.
Owner-defined criteria for privacy in a medical center facility
Authors: Rosenberg Carl J.
Published: October 2005

In this consulting project a program was developed to allow the occupants of the proposed building to be active participants in the evaluation and establishment of noise reduction and speech privacy requirements. Through personal interviews and a questionnaire, the doctors of a group medical practice were asked to rate their subjective reactions to speech privacy in their present facility. Objective acoustic measurements of NR between spaces were also made and correlated to the subjective responses. In this manner, the doctors had a self-defined scale of values to compare existing and proposed isolation for their newly designed facility. Also, the architect was able to present the owner with the cost implications of several alternative constructions which were proposed to provide different levels of privacy. The final decisions regarding materials and isolation could then be made by the doctors on terms that they themselves had helped to define. An additional measurement program established the maximum background-noise-level environment in which fetal heart beats could be satisfactorily measured.
Effect of a time-varying boundary on the sound field in an enclosure. II
Authors: Hwang Y.-F. , Tichy J.
Published: October 2005

By means of the theory presented in the preceding paper, the computer study of the effect of an oscillating wall on the sound field in an enclosure was performed. The parameters of the wall motion, room volume, wall impedance, and frequency range were chosen with respect to the application in the sound-power measurements at discrete frequencies in the low-frequency region. The application goal of the theory developed was to simulate the effects of moving diffusers frequently applied for sound-power measurements. The sound pressure was calculated in 150 randomly chosen points and several source positions. The statistical distributions of p2 amplitude and the variance of p2 have been calculated for various wall motion parameters. The results indicate that the wall oscillation has a major effect on the variance of the spatial distribution of p2, which decreases considerably with increasing amplitude of wall oscillations.
Role of duration in disambiguating syntactically ambiguous sentences
Authors: Lehiste I. , Olive J. P. , Streeter L. A.
Published: October 2005

The present study investigated whether the prosodic cue (duration) serves to disambiguate syntactically ambiguous sentences. An example of one of the ten sentences used is, “The hostess greeted the girl with a smile.” Some of the sentences had two alternative bracketings, e.g.: “The hostess [[greeted] [the girl]] [with a smile],” and “The hostess [greeted] [[the girl] [with a smile]],” while others did not. In this experiment, the duration of certain key words was systematically varied. The groups of words that were varied in this example were: “greeted the” and “girl with a”. The test sentences were presented to subjects who chose between the two alternative meanings. The results indicated that only sentences in which the two meanings were represented by two distinct bracketings were disambiguated by durational cues.
Identification and discrimination of place of articulation of nasal consonants
Authors: Larkey L. S. , Wald J. , Strange W. , Jenkins J. J.
Published: October 2005

A set of 10 nasal-stop vowel syllables were constructed on a Glace-Holmes synthesizer; nasality was cued by a single nasal resonance at a center frequency of 265 Hz. Syllables differed in transitions of second and third speech formants over a range sufficient to produce the perception of /mæ/, /næ/, and /ŋæ/. Sixteen subjects were tested on identification and oddity discrimination of these stimuli presented both forward (CV) and backward (VC). Identification functions showed sharp boundaries between phonemic categories for seven subjects in the CV condition and 14 subjects in the VC condition. In general, discrimination was closely related to identification for individual subjects; that is, discrimination tended to be categorical. Discrimination functions revealed more accurate performance for the VC stimuli than for the CV stimuli for most subjects. In particular, the VC discrimination functions for 11 subjects showed a peak between the stimuli identified as /æn/ and /æŋ/, while the comparable CV functions showed no such peak between /næ/ and /ŋæ/. Three of the other five subjects showed equally accurate discrimination of both CV and VC stimuli. These results suggest that discriminability of a phonemic distinction is sensitive to the particular syllabic position in which the distinction occurs in the language.
Perceptual organization of frequency-inverted speech
Authors: Yilmaz Huseyin
Published: October 2005

Listening experiments were performed in which two forms of frequency inversion were applied to ordinary speech corresponding to the “grave-acute,” and “compact-diffuse” transformations. The spoken vowels were transformed into different sounds which were also recognizable as vowels. The results are shown to be easily explainable with reference to a perceptual space. On the other hand, it is shown that the formant plot of frequency-inverted vowels falls far outside the range of normal vowels. It is concluded that the formant plot does not seem to be viable as a means for predicting the perceptual results of various observable transformations. Further details of the experiment and theoretical concepts are discussed.
Cost of noise control as seen by a public utility
Authors: Carlson John P.
Published: October 2005

Promulgation of federal, state, and local noise control regulations may require electric utilities to reduce noise emissions. Equipment requiring noise abatement includes central power station, substation, and street excavation operations. Purchasing new noise-controlled equipment, retrofitting existing equipment, and acquiring additional real estate for acoustic buffer zones are discussed relative to noise regulation compliance. Costs to abate major power plant noise sources including large fans, steam vents, exterior walls, and alternate cooling systems (cooling towers) are discussed. Economic trade-offs between sub-station transformer source noise emissions and external noise controls are presented. An example of costs for purchase of new street excavation equipment for compliance with a local noise control code is explored.
Ranking competing noise control projects using benefit-cost analysis
Authors: Ward Thomas L.
Published: October 2005

This paper is a brief tutorial overview of a technique of benefit-cost analysis. The procedures for making the analysis are summarized. These include establishing the discount rate, calculating the benefit-cost ratio as a measure of effectiveness and comparing that measure with the criterion for feasibility. Two areas of concern have troubled some analysts. These are the numerator-denominator controversy and the ranking of competing alternative projects. It is shown how both are resolved so that the benefit-cost ratio method always yields the same results as other economic measures. A short bibliography provides an entry to the most useful recent literature.
Dichotic lag effect and intensity
Authors: Berlin Charles I. , Berlin Harriet , Cullen John K. , Hughes Larry F.
Published: October 2005

Preliminary findings in our laboratory have suggested that the “lag effect” [M. Studdert-Kennedy, D. Shankweiler, and S. Schulman, J. Acoust. Soc. Am. 48, 599–602 (1970); C.I. Berlin, S. Lowe-Bell, J.K. Cullen Jr., and C.L. Thompson, J. Acoust. Soc. Am. 53, 699–708 (1973)] may change at intensities below 75 dB SPL. An experiment is currently underway studying the “lag effect” at intensities of 50–80 dB SPL and preliminary data suggest there may be a lead effect at low intensities which reverses as both competing syllables are presented at higher intensities. [Supported by National Institutes of Health, USPHS Grant No. NH 11647-01.]
Dichotic performance for temporally altered consonant-vowel tokens
Authors: Cullen John K. , Tobey Emily A. , Hughes Larry F. , Berlin Charles I.
Published: October 2005

Eight normal subjects were tested in a dichotic consonant-vowel identification task where synthetic tokens of the stops + [æ] ranging in duration from 40 to 296 msec were used as challenges against 296-msec tokens from the same synthetic set. Subjects were required to identify both items in a dichotic pair. As challenge durations were reduced, their dichotic performance dropped paralleling monaural intelligibility, voiceless items being more severely affected than voiced items. Performance for the nonshortened items increased as the duration of the challenges dropped, in a manner not entirely reflecting the challenge intelligibility loss. Additionally, a “backward-masking” effect of temporally remote vowel segments on competing consonant identification was clearly shown. [Supported by National Institutes of Health, USPHS Grant No. NH 11647-01.]
Performance of subjects with temporal lobe lesions on a dichotic consonant-vowel identification task with unilateral masking
Authors: Cullen John K. , Berlin Harriet L. , Berlin Charles I.
Published: October 2005

In previous work with normal subjects, performance trading for the masked and unmasked ear was shown in a dichotic consonant-vowel identification task with unilateral masking [C.L. Thompson, D. Samson, J.K. Cullen Jr., and L.F. Hughes, J. Acoust. Soc. Am. 55, 435(A) (1974)]. This study tested four subjects with temporal lobe lesions involving the superior gyrus in a similar task. When masking was applied to the ear contralateral to the lesion, both contralateral and ipsilateral ear performance were affected only slightly. When masking was applied to the ear ipsilateral to the lesion, performance of the ipsilateral ear decreased. Contralateral ear performance did not increase, however, until the ipsilateral signal-to-noise ratio was reduced to 12 dB. These data suggest lesions of the superior temporal gyrus serve to effectively decrease the signal-to-noise ratio for speech information presented through the lesion-contralateral ear. [Supported by National Institutes of Health, USPHS Grant No. NH 11647-01.]
Reinterpretation of the “lag effect” in dichotic listening
Authors: Speaks Charles , Niccum Nancy , Jones Tom
Published: October 2005

CV syllables were presented dichotically and with the left-ear (LE) syllables delayed by intervals ranging from 20 to 150 msec. The “lag effect,” where scores for the lagging LE exceed those for the leading RE, occurred only with voiced stops in RE, and mainly when voiced stops in RE were paired with voiceless stops in LE. For all types of CV pairs, LE scores increased linearly beyond 20-msec delay and were asymptotic by 80 msec. RE scores, however, did not decrease with LE lag unless voiceless stops in LE were paired with voiced stops in RE. There was no evidence that the later-arriving LE syllable interrupted processing of the RE syllable [M. Studdert-Kennedy et al., J. Acoust. Soc. Am. 48, 599–602 (1970); C.I. Berlin et al., J. Acoust. Soc. Am. 53, 699–709 (1973)] or that backward masking was involved [Pisoni and McNabb, Brain and Language 1, 351–362 (1974)]. We believe that the “lag effect” has an acoustic origin, and that it exists mainly because crucial formant-transition cues in the LE syllable are released from competition with smaller temporal intervals by lagging the LE syllable than by lagging the RE syllable.
Property detectors for bursts and transitions in speech perception
Authors: Blumstein S. E. , Stevens K. N.
Published: October 2005

Relevant acoustic cues for signaling place of articulation values for stop consonants include the frequency of the burst and the range of the F2 and F3 transitions. A series of adaptation experiments was initiated to investigate the relative importance of these cues in perception. The test continuum consisted of 14 synthetic stimuli in which F2 and F3 were systematically altered to range along the [b d g] phonetic dimension. The adapting stimuli consisted of: full cues in which the place of articulation dimension was signaled by burst as well as transitions; partial cues in which place was signaled by transitions only; and conflicting cues in which the burst frequency signaled one phonetic dimension (e.g., [d]), whereas the transitions signaled another phonetic dimension (e.g., [g]). Adaptation with either the partial or full cue produced significant shifts in the place of articulation boundaries, with the full cue producing a slightly larger adaptation effect. The conflicting cue produced no significant shifts in adaptation. These results are interpreted in terms of a model that postulates a set of property detectors sensitive to acoustic events at stimulus onset. [Supported in part by an NIH grant.]
Articulatory characteristics as a cue for the perception of bilabials /b, w, m/
Authors: Kasuya H. , Takeuch S. , Kido K.
Published: October 2005

This paper describes some findings about the role of articulatory parameters in perceiving bilabials /b/, /w/, and /m/ in an intervocalic context (/aCa/), based on speech sounds synthesized with an articulatory model. In the model, the time-varying patterns of lip-opening area were approximated by parabolic functions based on measurements obtained from a high-speed motion picture of the utterances /awa/, /aba/, and /ama/. The parameters specifying the patterns were the minimum value of the lip-opening area (Sm) and the transition duration between the minimum and stationary values of the lip-opening area (Tt). Sm's and Tt's were varied from −0.3 cm2 to 1.0 cm2 (10 items) and from 40 msec to 200 msec (nine items), respectively. The results of the listening tests showed that the distinction between /m/ and /w/ as well as that between /b/ and /w/ depended almost only on the value of Sm, but not on the transition duration Tt. Thus it can be concluded that the degree of lip closure plays a very important role as a cue for distinguishing bilabial consonants in an /aCa/ context, irrespective of the nasalization of the sounds.
Effect of asymptotic threshold shift in the neural firing patterns of the rat cochlear nucleus
Authors: Henderson Donald , Møller Aage R.
Published: October 2005

Rats were exposed to broad-band noise (spectral level = 50 dB ± 5 dB between 1000 and 10 000 Hz) for three to five days. Single neurons (N = 60) were sampled in the dorsal and ventral cochlear nucleus. Tuning curves were elevated 30–40 dB re normal [A.R. Møller, Acta Physiol. Scand. 76, 503–512 (1969)]. The slopes of the low-frequency sides of the tuning curves were considerably shallower than normal, thereby making the bandwidth of the tuning curve wider. The inhibitory areas of the tuning curves were either not measurable, or were much more elevated than the excitatory area. Light microscopic analysis of the cochleas revealed no changes in the sensory epithelium.
Multiunit recording from the auditory cortex of tree shrews
Authors: Manley Judith A. , Milner P. M.
Published: October 2005

Multiple units were recorded from the projection area of the medial geniculate in awake unrestrained tree shrews (Tupaia). Platinum iridium wire electrodes (20 μ) were used to record from small groups of cells for periods up to six months. During this time the size and waveform of the spikes remained constant. White noise, pure tones, and ten different Tupaia vocalizations were used as stimuli. Almost all the electrode placements showed responses to some of the vocalizations, but only two-thirds responded to white noise and less than half to pure tones. Most cell groups responded to several vocalizations but the responses were labile, i.e., sometimes different calls were effective on different days. Some calls were consistently more reliable in producing a response than others, while noise and tones were the least reliable stimuli. Responses to pure tones tended to be broadly tuned. Raster patterns show the response of cell groups was very variable from one trial to the next. Response patterns, as shown by PST histograms, were mostly sustained with latencies of 80 to 120 msec. Intensity of the vocalizations affected latency, but did not change the response pattern. Responses tended to habituate in 10–15 trials.
Intensity functions of neurons in the auditory cortex of the unanesthetized monkey
Authors: O'Connor Thomas A. , Pfingst Bryan E. , Miller Josef M.
Published: October 2005

The relation between stimulus intensity and single-unit activity was investigated in the auditory cortex of awake rhesus monkeys. Units were recorded from monkeys performing a simple auditory reaction time task, from trained nonperforming monkeys, and from untrained monkeys. The auditory cortex was approached in the vertical stereotaxic plane. Seventy-five percent of the tracts were marked for subsequent histological verification. Neural responses were analyzed in terms of frequency of firing, initial latency, and pattern of response. Intensity functions were obtained using pure tones at approximately the best frequency of the unit and/or white noise stimuli. Units studied possessed best frequencies spanning the entire range of monkey auditory sensitivity. The majority of responses involved excitatory-on components. For most of these on-responses frequency of firing was a monotonically increasing function of intensity. The dynamic range of these cells included some with a range as small as 10 to 20 dB, but in the majority the dynamic range was 50 dB or greater. Detailed characteristics of the changes in cell response (including variability of response) with changes in stimulus intensity and differences observed in behaving, nonbehaving, and untrained animals are described. [Supported by NIH Grants NS-08181, GM-00260, and RR-00166.]
Response plasticity of neurons in auditory cortex of the untrained rhesus monkey
Authors: Pfingst Bryan E. , O'Connor Thomas A. , Miller Josef M.
Published: October 2005

Evoked responses from single neurons in auditory cortex were examined in untrained rhesus monkeys under three states: (1) monkeys' eyes open and occasionally tracking a moving object, (2) eyes closed for at least 30 sec, and (3) anesthetized with 5 or 10 mg/kg ketamine. Pure-tone or white-noise stimuli were presented monaurally to the contralateral ear. The subjects' heads were rigidly restrained. Marked changes in evoked response were frequently seen as the animal drifted from state 1 to state 2. Most commonly the response weakened or disappeared altogether, but occasionally more complex changes occurred in a unit's response pattern, threshold, or tuning characteristics. Ketamine produced various effects, depending on the unit observed: in some cases the evoked response disappeared while in others it became very stable. The changes in responsiveness could not be accounted for by small changes in stimulus intensity which might result from pinna movements or middle-ear muscle contractions, since they were often more dramatic than changes produced by even large changes (>30 dB) in intensity. The results reemphasize the need for careful specification of the subject's behavioral and physiological state in studies of neural coding. [Supported by Grants NS-08181, RR-00166, and GM-00260 from NIH.]
Auditory neurons in the Monitor lizard
Authors: Manley G. A.
Published: October 2005

The basilar papilla of the Bengal monitor lizard, Varanus bengalensis is a moderately differentiated auditory receptor, 1.6 mm in length. Unlike most lizard basilar membranes, there is a pronounced constriction one-third of the length from the superior end, with no hair cells in the constricted region. Using extracellular microelectrode recording, activity patterns have been studied in 46 neurons so far, from the cochlear nucleus of this species. These preliminary data indicate that the tuning curves (characteristic frequencies up to 2.4 kHz) mostly resemble those previously obtained from the poorly differentiated auditory organs of the leopard lizard. In reptiles which have a highly differentiated, tapering basilar membrane, the tuning curves are consistently steeper on the high-frequency side and the Q10 dB or sharpness increases with increasing CF. In the leopard lizard and Varanus, however, either side of the tuning curve may be steeper and the Q peaks in the middle of the frequency range, near 950 Hz. Unlike in the leopard lizard, however, no complex tuning curves were found. It may be that, in Varanus, the basilar membrane constriction reduces the generation of complex tuning curves. More conclusive interpretations must await the elucidation of innervation patterns in these species.
Cytoarchitecture of the cochlear nucleus in the hedgehog and tree shrew
Authors: Casseday J. H. , Marsh D. S.
Published: October 2005

The superior olivary complex of the hedgehog (Paraechinus hypomelas) differs from most mammals in having a large lateral superior olive but no medial superior olive. In an attempt to determine if this structural difference would be reflected in the organization of the cochlear nucleus, we compared, in Nissl preparations, the cytoarchitecture of the cochlear nucleus of the hedgehog with that of the tree shrew (Tupaia glis), another insectivore which does have a medial superior olive. While in both species most of the major cell types seen in the cat [Osen, J. Comp. Neurol. 136, 453–484 (1969)] were evident, a striking difference was found in the organization of the anteroventral cochlear nucleus. In the tree shrew this nucleus is subdivided into an anterior portion which contains large spherical cells and an adjacent posterior region which contains smaller spherical cells. In the hedgehog a region of large spherical cells could not be found; the absence of this area of the anteroventral cochlear nucleus may be related to the absence of the medial superior olive. [Supported by a grant from the National Science Foundation.]
Spatially ordered convergent projection from the auditory thalamus to and from A-I in the cat
Authors: Merzenich M. M. , Colwell S. A.
Published: October 2005

Microelectrode mapping experiments were conducted in A-I in cats to determine the physiological dimensions of the field. Combined horseradish peroxidase (HRP) and tritiated amino-acid (TAA) were then injected at one or more known locations in A-I, revealing the arrays of neuronal afferents and terminal efferents to and from these physiologically defined A-I loci. Among the results were the following: (1) There is a discrete, spatially ordered convergent projection from a continuous sheet of neurons passing through the medial and ventral divisions of the medial geniculate body (MGB) to any given locus in A-I. (2) The arrays of projecting neurons approximately parallel the axes of orientation of dendrites and the paths of fibers of the brachium of the inferior colliculus within pars lateralis and pars ovoidalis of the ventral division of MGB. (3) Within pars lateralis, projecting neuronal arrays from distinct laminae. Lowest-frequency A-I sites receive projections from caudolateral neuronal MGB laminae; higher-frequency MGB laminae are continuously added medially and anteriorally. (4) The efferent projection from any A-I locus to MGB overlies exactly the array of thalamic neurons projecting to that same cortical site. [Supported by NIH Grant NS-10414.]
Chemical equilibrium constants by differential ultrasonic absorption
Authors: Fisher F. H.
Published: October 2005

In 1953 Kurtze and Tamm observed a reduction of sound absorption in MgSO4 solutions upon the addition of NaCl. From this reduction it is possible to determine the concentration of (NaSO4) ion pairs. A new equilibrium dissociation constant KD=0.073 is obtained, considerably lower than the accepted value of KD=0.019. The differential ultrasonic absorption technique is a new independent approach to the study of chemical equilibria that has proved to be very useful for the study of a difficult unsymmetrical electrolyte. Two recent experimental papers using independent techniques, electrical conductance and potentiometric measurements, support the new value. The technique should be useful for the study of many other equilibria. [This paper represents results of research sponsored by the Office of Naval Research and the National Science Foundation Grant GA 18763.]
Excitation and scattering of electroelastic surface waves via an integral equation approach
Authors: Sabbagh Harold A. , Krile Thomas F.
Published: October 2005

The determination of the surface charge distribution on the fingers of an interdigital transducer is the single most important step in the analysis of such transducers. Similarly, the determination of the stress distribution at the interface of a plane surface and a topographical irregularity is the single most important step in computing the scattering of a surface wave by such an irregularity. In this paper we apply the Fourier transform to derive an integral equation for the surface charge distribution on a finite interdigital transducer. The Fourier integral equation is inverted by utilizing an expansion of the surface charge in piecewise polynomials and then employing the method of moments (or Galerkin's method) to reduce the integral equation to a matrix equation which is then solved on the computer. The evaluation of the matrix elements is accomplished by a combination of analytical (contour integration) and numerical techniques. A similar approach is made to solve the problem of scattering of a surface wave from a topographical irregularity.
Ambient noise under Antarctic sea ice
Authors: Kibblewhite A. C.
Published: October 2005

Underwater ambient noise spectra and amplitude distributions are described for data recorded during late spring conditions under the ice in McMurdo Sound, Antarctica. The ice was fast to the shore and provided 10/10 cover at the time. While the ambient noise was characterized by intense biological activity a diurnal, nonbiological component became apparent during the three-day recording period. This component was found to be similar to that observed in Arctic measurements and attributed to surface cracking of the ice sheet under the influence of thermal stressing. In certain respects, however, this noise component was found to be different from its Arctic counterpart.
New, empirical expression for sea surface backscattering strength
Authors: Welton P. J. , Campbell R. J.
Published: October 2005

A new, empirical expression for the sea surface backscattering strength has been developed. Previously developed empirical expressions considered only constant coefficients and therefore have quite limited ranges of validity. The new backscattering strength expression has variable coefficients and is valid for a wide range of frequencies, wind speeds, and grazing angles. In particular, the new expression saturates at high frequencies and/or wind speeds; this is in agreement with both theoretical and experimental considerations which indicate that the scattering strength should become frequency independent under these circumstances. Comparison of this new expression with experimental data shows good agreement for frequencies from 0.1 kHz to 60 kHz, wind speeds from 1 to 35 knots, and grazing angles from 5° to 80 °.
Backscattering from a cylinder with variable surface impedance
Authors: Ellison W. T.
Published: October 2005

An analysis based on Kirchhoff's approximation is undertaken for the backscattered farfield from a rigid finite cylinder with a strip of variable surface impedance exposed to an obliquely incident plane wave in an infinite acoustic medium. The variable surface impedance is finite and complex and is axially oriented over the full length of the cylinder. The analysis indicates that for strip angles less than the angle subtended by the first Fresnel zone, complete cancellation of the backscattered field can be achieved by judicious choice of the surface impedance.
Real-time digital processing of acoustic form function data
Authors: Dardy H. D. , Bucaro J. A. , Flax L.
Published: October 2005

Acoustic characterization of elastic objects insonified in water have long been of interest as a means of object recognition. One proposed technique utilizes pulse transmitted and received echoes to allow analysis of data in terms of response spectra. We present an efficient method for obtaining this data utilizing a minicomputer controlled digital processor; this technique, when coupled with various incident time pulses, allows real-time visualization of acoustic form functions over a wide ka region. Considered are spheres and cylinders; agreement with theoretically obtained results is presented. Such a system can afford an extremely accurate and efficient real-time characterization of sonar targets through employment of their respective form functions.