bluuebunny/crossref_metadata_2025 huggingface dataset:
High-amplitude/low-frequency impulse calibration of microphones: A new method
Authors: Hunt Alan , Schomer Paul D.
Published: October 2005

This paper describes a new method to measure the peak amplitude response and the droop (low-frequency response) of a microphone and its associated amplifiers. The requirements for the new method was that it be simple, inexpensive, and accurate. An acoustic “step function” would be an ideal source for testing the large-amplitude and low-frequency response of microphones, especially for measurements of impulsive noise. Unfortunately, a positive-going acoustical step-function source is difficult to obtain. This method involves the use of a negative step-function input which is applied by closing a microphone inside a thin membrane which is inflated and then burst. The sudden decrease in pressure represents a negative-going step-function input to the microphone. The peak output voltage produced by the microphone must be proportional to the initial static pressure within the membrane and the return (decay) of the voltage output of the microphone to zero directly represents the droop of the microphone and system. The low-frequency cutoff of the system is easily calculated from the time constant of the decay curve.
Shape optimization of pressure-gradient microphones
Authors: Norum T. D. , Seiner J. M.
Published: October 2005

Recently developed finite-element computer programs were utilized to investigate the influence of the shape of a body on its scattering field with the aim of determining the optimal shape for a pressure-gradient microphone. Circular cylinders of various aspect ratios were evaluated to choose the length to diameter ratio best suited for gradient microphone application. Alterations of the basic cylindrical shape by rounding the edges and recessing at the centerline were also studied. It was found that for a ±l-dB deviation from a linear pressure-gradient response, a circular cylinder of aspect ratio near 0.5 was most suitable, yielding a useful upper frequency corresponding to ka = 1.8. The maximum increase in this upper-frequency limit obtained through a number of shape alterations was only about 20%. An initial experimental evaluation of a single-element cylindrical pressure-gradient microphone of aspect ratio 0.14 utilizing a piezoresistive type sensor was also performed and is compared to the analytical results.
Improved design of spherical multimode hydrophone
Authors: Ko S. H. , Pond H. L. , Alatalo F. A.
Published: October 2005

An earlier model for a spherical multimode hydrophone [S.H. Ko, G.A. Brigham, and J.L. Butler, J. Acoust. Soc. Am. 56, 1890–1898 (1974)] is able to predict the hydrophone response curves in which resonances are present. In order to eliminate these resonances, the surface area of a given hydrophone is divided into selected areas which are separated from one another and such that the sum of voltages from the elements of an area is zero for the resonant mode, while the sum of voltages due to the nonresonant modes still provides the essential information about the direction of the incoming acoustic wave. This method was used successfully to remove the lowest (n = 3) resonant mode [H.L. Pond, F.A. Alatalo, and S.H. Ko, J. Acoust. SOc. Am. 60, Suppl. (1976)]. However, the elimination of the n = 3 mode is not sufficient. For higher modes, the technique developed here is to keep only two zones instead of adding more zones and to select the position of the line of division between zones by using a weighting factor, so that the, n = 3 mode resonance is eliminated and the effect of the resonance for the other modes is greatly reduced. Experimental results are in agreement with the theoretical results. [Work supported by CNM.]
Operation of an ultrasonic flowmeter on a sodium loop of a fast breeder reactor
Authors: Karplus H. B. , Forster G. A.
Published: October 2005

The flow of fluid in a pipe is determined from the upstream and downstream flight times of ultrasonic (4 MHz) pulses traveling obliquely across the pipe. Temperature effects on dimensions, sonic velocity, refraction angles, etc., are compensated from the measured mean-pulse travel times. This mean-pulse travel time also yields mean fluid temperature. This permits a pair of instruments on the hot and cold leg of a heat transfer loop to give total power flow. Total time delays across the pipe were measured over the temperature range 350°–70 °C and compared with values computed based on expansion coefficient and elastic modulus data from the Nuclear Materials Handbook. Ultrasonically measured flow rates were compared with the installed electromagnetic and hydrodynamic flowmeters as well as with a special neutron activation flow calibration technique. The transducers for the ultrasonic system were specially designed to be clamped to the outside of the hot pipe using gold foil between optically flat surfaces with a clamping force of 2000 N.
Two-phase model to predict the inelastic, seismic response of a steel frame
Authors: McNiven Hugh D. , Matzen Vernon C.
Published: October 2005

Previous papers reported on the use of a nonlinear differential equation (containing a Ramberg-Osgood term) to represent the inelastic, seismic behavior of a single-story steel frame. The structure was tested on the shaking table at the Earthquake Engineering Research Center at the University of California, Berkeley. The correlation between the predicted and measured acceleration time histories was exceptionally good. However, the computed displacement time histories did not predict the permanent offset experienced by the structure. The reason for this shortcoming is that the hysteretic behavior of virgin steel is different in the first inelastic excursion than it is in subsequent excursions. The Ramberg-Osgood model can represent only the subsequent hysteretic behavior. To alleviate this deficiency, the present paper presents a two-phase model. One set of parameters is established for the initial phase of the response, in which hysteretic behavior is approximately elastic, perfectly plastic; and another set is established for the second phase, in which the hysteretic behavior has a more rounded transformation from elastic to plastic deformation. The importance of this work lies not so much in its application to steel, as in its potential for application to degrading materials like reinforced concrete and masonry.
Tale of two standards — and what happened after
Authors: Corliss Edith L. R. , Roberts Jean , Stewart Kenneth C. , Moore Elizabeth F.
Published: October 2005

In 1969, the American National Standards Institute adopted a set of standards for normal, unimpaired hearing based upon data snmmarized by the International Standards Organization (ISO). In the USA, the American Standards Association (Later, ANSI) had maintained, since 1951, a set of standards based upon data derived from the National Health Survey of 1935–1936. There have been several additional National Health Surveys, covering groups of various ages, with medical examinations and carefully controlled pure-tone audiometric testing making possible various criteria for selection of the normal range. Despite the wider range of ages and the use of various criteria for selection of normality, the results of these show rather close agreement with one another, and with the earlier survey data as well. The implicaitons of these results to the description of normal, unimpaired hearing will be discussed.
Speech intelligibility in noise with ear protectors
Authors: Abel S. M. , Alberti P. W. , Riko K. , Madsen R.
Published: October 2005

This research investigates the effect of ear protectors on the intelligibility of speech in noise. The listeners are adults, 35–65 years old, with normal hearing, bilateral high frequency or flat loss between 500 and 4000 Hz. They may be fluent or poorly conversant with spoken English. Taped lists of 25 words are presented free field under a variety of conditions in which the signal-to-noise ratio (+5 and −5 dB), the spectrum of the background noise (white versus crowd), and the presence of ear protection are varied. Preliminary data indicate that in normal listeners the number of words correctly repeated decreases as signal-to-noise ratio decreases and that speech perception is poorer in noise than in quiet. When ear protectors are worn for speech presented in crowd noise some improvement in hearing is evident. In contrast, for this condition subjects with a high-frequency loss show a marked deterioration in performance. [Work supported by Ontario Min. Health.]
Effect of selective adaptation on the discrimination of small differences in voice onset time (VOT)
Authors: Ganong William F.
Published: October 2005

The effect of selective adaptation (i.e., listening to a rapidly repeated syllable) on the discrimination of voiceless stimuli which differ only in VOT was investigated. In an AX procedure under conditions of minimal stimulus uncertainty, subjects in the unadapted state were able to discriminate (d′=1)small (5 msec) differences in the VOT of stimuli from the voiceless end of a /ba/—/pa/ continuum. Control experiments showed this discrimination was not based on memorization of the aspiration noise waveform, and that subjects could represent small differences in VOT in long-term memory. Adaptation depressed discrimination slightly, showing that adaptation can affect a perceptual task which does not depend on phonetic categorization. The data were not precise enough to indicate whether adaptation affected a level sensitive to the acoustic similarity of the adapting and test stimuli or to the relationship of the adapting stimulus to the phonetic category.
“Cross talk” between voicing and place cues in initial stops
Authors: Repp Bruno H.
Published: October 2005

The dependence of the voicing boundary on place cues was investigated by orthogonally varying the F2 and F3 transition onset frequencies of syllable-initial stop consonants, as well as their voice onset time (VOT). There is evidence for changes in the voicing boundary tied to the perceived place category, but there are also reliable changes within place categories. The latter are often irregular and subject to large individual differences. A much more consistent finding is the dependency of the place boundaries on VOT: The labial-alveolar and alveolar-velar boundaries converge as VOT increases, resulting in a reduction of the size of the alveolar category. This effect appears to be a continuous function of VOT, i.e., it does not directly depend on the perceived voicing category. [Work supported by NICHD.]
Community reaction to impulse noise
Authors: Seshagiri Baily V.
Published: October 2005

A survey has been conducted to assess the reaction of communities exposed to impulse noise. Three communities were selected in different cities of Ontario, where significant numbers of people are exposed to impulse noise of a particular type—that produced by the operation of drop forges. Approximately 600 interviews were completed on a double-blind basis using a specially constructed questionnaire. The noise environment in the survey areas was established by analog and digital monitoring. Analysis of the data indicates significant correlation between disturbance responses and the measured impulse noise level. A wide range of noise descriptors have been tested, including impulse level measured with slow, fast, and impulse response, equivalent sound level, percentile levels, and level above ambient. Multiple-regression analysis has been carried out to investigate the effect of independent variables such as income, age, education, etc.
Symmetry in the direction of substitution for segmental speech errors
Authors: Shattuck-Hufnagel Stefanie , Klatt Dennis H.
Published: October 2005

A model of the utterance production process is proposed in which segmental substitution errors arise from confusion between two simultaneously available and similarly represented planning segments. This model predicts that each segment will serve equally often as the intended target and as the intrusion in errors. Further, the relative frequency that intended segment type x is replaced by intrusion segment type y should be the same as the relative frequency that y is replaced by x, for all x≠y of the confusion matrix. These predictions are confirmed by the pattern of substitutions for 23 consonantal segments in two independently collected corpora of 1351 and 1471 errors. A small number of consistent exceptions are discussed in light of a patatalization process that occurs in spoken English. One interesting implication of these observations is that “stronger” segments do not tend to replace “weaker” segments in speech errors, no matter what the definition of strength. (Work supported in part by an NIH grant.]
Suppression of aerodynamically induced cavity pressure oscillations
Authors: Shaw L. L.
Published: October 2005

A flight test program was performed to gain further insight into the phenomenon of flow-induced cavity pressure oscillations and to evaluate the effectiveness of numerous suppression concepts in eliminating or reducing the pressure oscillations. The cavities tested were rectangular with approximate dimensions of 17-in. long, 8-in. deep, and 9-in. wide and were instrumented with microphones, static pressure ports, and a thermocouple. The flight speeds ranged from Mach number 0.6 to 1.3 at pressure altitudes of 3000, 20 000, and 30 000 ft. The suppression devices included leading edge spoilers and deflectors and trailing edge ramps and deflectors. Several combinations of these were tested. The results indicate that the flow-induced pressure oscillations in a cavity, of the dimensions tested and for the speed range tested, can be significantly reduced with leading edge spoilers in conjunction with a trailing edge ramp. A 40-dB reduction was achieved for the predominant modal frequency. Other combinations of the suppression devices afforded some reduction but the spoiler-ramp combination proved most effective.
Noise of deflectors used for flow attachment with STOL-OTW configurations
Authors: von Glahn U. , Groesbeck D.
Published: October 2005

For future STOL aircraft utilizing engine-over-the-wing (OTW) installations in which the exhaust nozzles are located above and separated from the upper surface of the wing, an external jet-flow deflector can be used to provide flow attachment to the wing/flap surfaces for lift augmentation. In the present work, the deflector noise in the flyover plane measured with several model-scale nozzle/deflector configurations is examined. The OTW configurations consisted of a circular nozzle (5.18-cm diameter) mounted 0.1 wing chord lengths above and aft of the wing leading edge. Wing chords (flaps retracted) of 33 and 49.5 cm were used. Tests included flap settings of 20° and 60° and jet Mach numbers of 0.6 and 0.8. The data indicate that the effective sound pressure level of the deflector peaks in the forward quadrant. With some deflector/wing combinations, a severe tone/haystack was obtained at a model-scale frequency near 6-8000 Hz. The effective sound pressure level is a primary function of deflector immersion in the jet flow and the deflector span. Peak deflector noise levels as much as 12 dB above those of other jet/flap interaction noise sources were obtained.
Sonic phase and group velocity in ice plates floating on water
Authors: Huang Peter H. , Mayer Walter G.
Published: October 2005

An expression for the phase velocity dispersion of vibrational modes for an ice plate floating on water is obtained which is consistent with the seemingly different expressions contained in the reflection coefficients given by various authors. Examples for different ice parameters are given, and the dispersion relations for the group velocities is shown to be more sensitive to variations in ice properties than is the phase velocity. [Work supported by the Office of Naval Research, U. S. Navy.]
Resonance theory for acoustic plane wave transmission through a fluid-loaded layer or plate
Authors: Fiorito R. , Madigosky W. , Uberall H.
Published: October 2005

Sound transmission through a fluid layer which is imbedded in lighter density fluid is analyzed in terms of a resonant transmission theory. Expressions for the transmission coefficient (T) have been obtained indicating that T can be decomposed into resonance terms corresponding to symmetric and antisymmetric propagation modes in the layer. A computer progarm is utilized to compute both total T and T for each resonance for several cases of interest. Dispersion curves for the layer are obtained and compared to calculations and experimental data in the literature. The resonance widths are also calculated and an interpretation of total T as a function of angle of incidence and frequency thickness product is made in terms of these individual resonances. A similar but more complicated analysis holds for the elastic plate.
Unusual characteristics of free bending waves in thick plates with fluid loading
Authors: Pierucci Mauro , Graham Thomas S.
Published: October 2005

Exact, steady-state solutions, representing straight-crested free bending waves, were calculated for the infinite Timoshenko-Mindlin plate with fluid loading. In general there are three different types waves, two of which are roughly similar to plate waves in vacuum, and a third wave which is unique to fluid-loaded plates. The unusual behavior of this third free bending wave is the subject of this paper. Calculated solutions are presented as loci of complex free bending wave numbers for steel plates and plates of a softer material for different conditions of fluid loading. The principal finding of this paper is that the loci of free bending wave number, and the character of the waves, change drastically with fluid density. Behavior under one fluid loading condition thus cannot be easily extrapolated to predict behavior in a different fluid. As a result of this work, it is concluded that nearfield solutions to plate radiation problems are more complicated than previously thought. One result of particular interest is that free bending waves in steel plates with water on one side are qualitatively different from those occurring with water on both sides. The results therefore have a very practical value.
The coincidence of higher-order acoustic modes in pipes with the pipe vibrational modes
Authors: Walter J. L. , McDaniel O. H. , Reethof G.
Published: October 2005

A phenomenon which occurs in aerodynamic noise problems in piping systems is explained as suggested by Bull [M. K. Bull, 9th International Congress on Acoustics, 1977] and as concurrently developed by the authors. The phenomenon, reported by several researchers [A. V. Karvelis, Ph. D. thesis (PSU, 1975); J.G. Seebold, ASME, 1972, Bull, op.cit.], is a sharp drop in pipe transmission loss which occurs near the cutoff frequencies of many of the internal higher-order acoustic modes, but does not occur far above cutoff, even though the mode is propagating. An examination of the acoustic and shell wave propagation has shown that coincidence, i.e., a match in wave number and phase velocity, occurs in the axial direction near the cutoff frequencies. An analytic model is presented that demonstrates this coincidence using classical theory. [Work supported by NSF.]
Time-domain processing of target range information by central auditory neurons in the echolocating bat, Eptesicus fuscus
Authors: Feng A. S. , Simmons J. A. , Kick S. A.
Published: October 2005

Echolocating bats (Eptesicus fuscus) perceive either monaurally or binaurally the range of sonar targets with an acuity of about 1 cm, or a time delay acuity of about 60 μsec. Single-unit recordings from cortical and midbrain auditory neurons in unanesthetized bats indicate response properties to stimuli consisting of pairs of simulated echolocation signals (three-harmonic descending FM sweeps with energy from 23 to 100 kHz) with naturally occurring transmission-echo time delays and intensity differences. While many neurons respond to both transmissions and echoes given sufficient intensities and long echo delays, some neurons respond exclusively to the pair when the time delay is within a narrow range. Their temporal response selectivity increases with decreasing overall absolute transmission-echo intensity but is independent of intensity differences between transmissions and echoes. These results demonstrate “tuning” of central auditory neurons to specific echo delays, providing the neural basis for target range perception in bats and possibly perception of temporal structure of sounds in other animals. [Work supported by NSF and NIH.]
A map of auditory space in the midbrain of the owl
Authors: Knudsen E. I. , Konishi M.
Published: October 2005

Auditory units that responded to sound only when it originated from a limited area of space were found in the lateral and anterior portions of the midbrain auditory nucleus (nucleus mesencephalicus lateralis pars dorsalis, MLD) of the owl. The response properties of these units were studied in five barn owls (Tyto alba) using a remotely controlled, movable sound source under free-field, anechoic conditions. The area of space to which such a unit responded was virtually independent of the nature (tone, click, or noise) and the intensity of the sound stimulus, and was defined as the unit's receptive field. Within a unit's receptive field could be found a small area to which the unit would respond with greatest vigor. This area of space was termed the unit's best area. Units in the lateral and anterior portions of MLD were systematically arranged according to the azimuth and elevation of their best areas. Units with contralateral best areas were located posterolaterally; units with ipsilateral best areas were located anteromedially. Elevation was arrayed along the dorsoventral axis with high best areas located dorsally and low best areas ventrally. [Work supported by NIH.]
Representation of interaural time and intensity differences for clicks at the brachium of the inferior colliculus in the rat
Authors: Clopton B. M. , Silverman M. S.
Published: October 2005

A click presented at one ear evokes a synchronous discharge in the brachium of the inferior colliculus on the opposite side. We sampled this response in rats by recording gross potentials from the surface of the brachium and observed the effect of clicks delivered to the ipsilateral ear on the magnitude of the response. Strong binaural interaction was observed as interaural intensity differences (IID's) and interaural time differences (ITD's) were varied. This interaction for IID's agreed with that previously reported for data pooled from single-unit observations, but the brachial potential technique allowed extensive IID and ITD combinations to be investigated in a single animal. Ipsilateral clicks that were more intense than contralateral clicks by 20 dB or more usually suppressed the contralateral response by at least 75%. Little ipsilateral suppression or even facilitation was observed for binaural clicks of equal intensity or with contralateral clicks more intense. ITD's of 200 μsec or less often had effects of similar magnitude, but the time effects' usually depended on IID's falling within the physiological range. Anesthetic effects were observed, and previous findings concerning the effects of developmental auditory deprivation and of selective lesioning of afferent pathways on binaural interactions in single neurons were confirmed.
Visual attention and tone-burst evoked potentials
Authors: Anderson B. W. , Oatman L. C.
Published: October 2005

Tone-burst evoked potentials were used to examine the differential effects of visual attention on different frequencies. Unanesthetized cats, chronically implanted in the auditory cortex, cochlear nucleus, and round window, were trained to attend to a visual stimulus while irrelevant stimuli (85 dB SPL tone bursts) were continuously presented at a rate of 1/sec. Peak-to-peak amplitudes of evoked potentials from the auditory cortex and cochlear nucleus were significantly reduced during the attention period when compared to the pretest and post-test control periods, but no significant changes were found at the round window (cochlear microphonic) for the same periods. The greatest suppression occurred in the middle frequencies (700–5000 Hz) although some suppression occurred across all frequencies. These data demonstrate that, during attention to a visual stimulus, auditory stimuli are attenuated maximally in the middle frequencies presumably via the olivocochlear bundle.
Auditory sensitivity in the rabbit determined by a conditional nictitating of membrane response
Authors: Martin G. K. , Lonsbury-Martin B. L. , Kimm J.
Published: October 2005

Auditory sensitivity was measured in New Zealand white rabbits trained by means of a behavioral technique utilizing classical conditioning of the nictitating membrane (NM) response. Conditioning trials consisted of the presentation of a 350 msec pure tone stimulus of which the final 100 msec overlapped with the occurrence of a shock to the posterior orbital region. A conditioned NM response was defined as a 0.5 mm deflection with a latency ranging from 130 to 260 msec following tone onset. Threshold and latency-intensity functions were collected from 500 Hz to 32 kHz using the method of constant stimuli under closed field conditions. Animals were most sensitive to test stimuli between 8 and 16 kHz with maximum sensitivities at sound pressure levels ranging from −1 to 11 dB SPL. For frequencies above 16 kHz and below 3 kHz, sensitivity rapidly decreased. The latency of the NM response was found to be an inverse function of stimulus intensity over a fairly large dynamic range similar to the latency-intensity functions obtained with operant reaction-time tasks. A number of features will be discussed that make the rabbit NM preparation a highly desirable behavioral and/or neurophysiological model for studying auditory phenomena.
Some unexplained properties of bird song
Authors: Beaver Joseph C.
Published: October 2005

The standard theory of avian “song” production of Greenewalt [Bird Song: Acoustics and Physiology, Washington, D.C.(1968)] claims a generation by the syringeal internal tympaniform membrane, vibrating at a “carrier frequency,” with amplitude modulation supplied by secondary vibration of the external labium. Whether these are driving or driven members is currently under investigation. However, several interesting questions remain either unaddressed or unresolved. Vertical spectrographic lines appear at the onset of “voicing” for some species comparable to those for unvoiced stops in human speech; “trills” (8–25 per sec) too slow for “amplitude modulation” are found in others. What are the articulatory correlates for these phenomena? Again, Greenewalt has argued that for species which generate a harmonic series (he admits even most passerines can and do), the harmonic emphasized varies in ratio to how much the bird descends below a “frequency threshold” where the Fourier transform is actuated, but Sutherland and McChesney [“Sound production in two species of geese,” Living Bird 4, (1965)] have demonstrated that the harmonic emphasized by the blue and snow goose depends on tracheal length. Tracheal length for many species is such that it could reinforce source-generated harmonics. Possible articulatory correlates for the first two phenomena are discussed, and for the third problem spectrographic evidence is presented to support a theory that a frequency capable of tracheal reinforcement serves as a “target,” or “home” frequency for many species.
Improving the acoustic properties of a dolphin tank
Authors: Poché Lynn B. , Rogers Peter H. , Carlson William V.
Published: October 2005

In many cases, dolphin tanks, like auditoriums, are designed with no special effort directed toward achieving acoustical perfection. Our measurements were to be made in a small pen in a large semicircular tank which was divided much the same as a railroad roundhouse, and contained seals and sea lions as well as dolphins. The walls were smooth concrete. Our object was to measure dolphin echolocation signals, and both reverberation and isolation presented serious problems. A wood lining which is echo suppressing in the frequency range of 10–150 kHz was developed and installed. The lining was constructed in 6-ft square curtain panels, which were made up from small (3.5 × 7 × 2.5-in.) blocks. This built-up construction was necessitated by the particular grain orientation and pressure treatment of the wood required. The development of a satisfactory surface configuration and grain orientation was carried out in a small laboratory tank using 12-in. square panels. Echo-reduction measurements made in the USRD Lake Facility on full-size panels and in the dolphin tank on the completed lining are in good agreement with the small-tank data and show about 15–30 dB echo reduction over the entire frequency range. Transmission loss increases from about 15 dB at 10 kHz to 40 dB at the high frequencies.
Prenatal sound transmission and exceptional antennae
Authors: Truby Henry M.
Published: October 2005

In the antedating of infantile speech-and-hearing acquisition, largely on the basis of cryprint and auditory response criteria, investigation of the neonatal period soon indicated the antecedental significance of the prenatal period [H. M. Truby, “Prenatal speech: A speculation,” CRI SR 2567 (1967)]. Observations of some years re early antenatal hearing in the developing human prenate (fetus) [B. Johansson, E. Wedenberg, and B. Westin, “Measurement of tone response by the human fetus,” Acta Otolaryngolica 57, 188 (1964)] corresponded with observable vocalization maturation in prematurely delivered infants (premies) of the 900-g-and-under class [H. Truby, J. Lind, and J. Bosma, “Cry sounds of the newborn infant (1960),” Acta Pædiatrica 163, 51 (1965)]. In exploration via contact microphony of the transmission properties of the amniotic sac, from midpregnancy on, the unique mother-prenate juxtaposition (Merriam-Webster IlI, p. 1229) is demonstrated to be eminently suitable for direct biophysiological sound transmission to the alert unborn baby of maternal speech, singing, humming, etc. —as well as shouting, screaming, crying, etc. — consequently placing said prenate in, for example, optimal oral-aural relationship for speech imprinting [H. Truby, “Prenatal and neonatal speech…” in Child Language — 1975, 57–101 (1976)]. Auscultation and stethoscopic recording at the external abdominal wall of the pregnant mother during speech, reveal a high order of intelligible speechsound transmission available in utero to the developing prenate. Serendipitously, the amniotic sac is revealed as an exceptional antenna for transmitting extracorporeally generated, conventional sound phenomena. Thus, in summation: The extended amniotic sac in vivo is an exceptional antenatal hearing medium, speechsound processor, and bioacoustic antenna and transmitter. [Author support: Pediatrics Department, Mt. Sinai Medical Center, Miami Beach, FL.]
Predicting the perceived magnitude of noise
Authors: Scharf B. , Hellman R. , Bauer J.
Published: October 2005

How can one best predict subjective ratings of noise magnitude loudness, noisiness, unacceptability, annoyance, etc.)? To answer this question we applied six sound-level weightings (A, B, C, D1, D2, and E) and five calculation systems (Mark VI, Mark VII, PNL, PNL with tone correction, and Zwicker's) to over 500 spectra from 23 different studies in which listeners judged noise magnitude, usually by a matching procedure. These spectra represented a wide variety of noises: aircraft, artificial, industrial, vehicular, household, etc. In general, the calculation systems predicted perceived magnitude with less variability and greater validity than the simple frequency weightings. Among the weightings the D's and E were better than B and C, with A falling in between. Among the calculation systems, Mark VI, Mark VII, and Zwicker's were about equal to one another and were better than PNL. Except for Zwicker's, the calculation systems were more accurate when the judged attribute was noisiness, acceptability, annoyance, or the like than when the attribute was loudness. [Research supported by the Office of Noise Abatement and Control, EPA.]
Tactile aids to speech reception
Authors: Miller J. D. , Scott B. L. , Filippo C. L. De , Ether N. P. , Sachs R. M.
Published: October 2005

Uses of the tactile sense to aid speech reception (usually in conjunction with lipreading) are reviewed. In the noninstrumental approach, the receiver's hands are placed on the talker. In one Instrumental approach, the unprocessed speech waveform or its envelope is transduced by a single vibrator. In those approaches guided by Helmholtzian place theory (“tactile vocoders”), the acoustic spectrum is analyzed into frequency bands and their envelopes are represented in an ordered, usually linear, spatial array on the skin. In the perceptual approach, auditory-perceptual dimensions relevant to speech are mapped onto tactile-perceptual dimensions In a manner arbitrarily selected by the experimenter. Observations at Central Institute for the Deaf will illustrate issues pertinent to the development and eventual clinical use of tactile aids. These are: problems of aid evaluation including appropriate training of subjects, criteria for selection of clients, and practial problems associated with daily use (safety, reliability, feedback, noise, and cost). A review of the accomplishments of the last 15 years substantiates that progress has been made toward clinical application. [Supported by NS 03856 and RR 00396.]
Evaluation of cochlear implants as an auditory prosthesis
Authors: Bilger R. C.
Published: October 2005

Thirteen persons who had single-channel electrodes implanted in scala vestibuli were subjected to a large battery of psychoacoustic tests. The battery included measures of sound-field thresholds; intensity, frequency, and temporal discrimination; masking; pattern recognition; word recognition; and lipreading. The results of these tests can be organized around the concept of listening through a single auditory channel. [This work was conducted under contract from NINCDS (NO1-NS-5-2331) to the Eye and Ear Hospital of Pittsburgh.]
Azimuth effects on the Kemar Mannequin
Authors: Gilman Samuel , Dirks Donald , Kumley Warren
Published: October 2005

The effect of head shadow and diffraction by the Kemar mannequin was explored with both pure-tone and pink-noise sound fields in an anechoic chamber. Polar recordings of 360° rotation of the mannequin were made for each 13 octave from 0.25 to 12.5 kHz with the point source on the same horizontal plane as the Zwislocki coupler in the mannequin's ear. Simultaneous magnetic tape recordings were transferred digitally to a computer programmed to compare the data with published human data. Comparisons were made for the full azimuth range for each frequency and for the full frequency range at each 15° of azimuth. Results shown that pink-noise data agrees closely with averaged human results [E.A.G. Shaw, J. Acoust. Soc. Am. 56, 1848–1861 (1974)]. Pure tone results show good correspondence with the same averaged human data at low and middle frequencies but show deviant peaks at higher frequencies. At least some of these variations appear to be related to detailed pinna geometry.
The locatability of vocalizations in Old World monkeys
Authors: Brown C. H. , Beecher M. D. , Moody D. B. , Stebbins W. C.
Published: October 2005

The acuity of directional hearing in Old World monkeys (Macaca) was assessed psychophysically through positive reinforcement operant conditioning procedures. The monkey's observing response, contact with the response disk, initiated a train of acoustic stimuli presented from the standard location, 0° azimuth. Intermittently the location of the stimulus changed from the standard to one of several comparison locations. Monkeys reported the detection of a change in the azimuth of the signal by releasing contact with the response disk. Thresholds for the acuity of acoustic localization were determined under free-field conditions in an anechoic chamber by the method of constant stimuli. Monkeys were tested with an array of natural calls and bandpass-filtered components of calm sampling several categories of conspecific vocalizations. The results indicate that frequency modulation and bandwidth were relatively more salient than the harmonic content of the call for directional hearing. The locatability of vocalizations may be selected by the biosocial context in which they are emitted. [Work supported by NSF.]
Perception of clicks in music
Authors: Gregory Andrew H.
Published: October 2005

Subjects were asked to judge the position of a click which occurred during a short piece of music. Clicks were on average judged to be later than their actual position for a slow tune, but almost no bias in the judgement of click position was found for a fast tune. The click and the music were presented through headphones to different ears, and the clicks were judged to be significantly later if they arrived at the right ear rather than the left. There was also a significant tendency for clicks to be attracted to phrase boundaries in the music. These last two results are similar to those from experiments with a click during speech, but the late judgements of a click in music contrasts with the tendency for early judgements of a click in speech.
Serial auditory thresholds in relation to noise and other factors
Authors: Roche A. F. , Siervogel R. M. , Himes J. H. , Johnson D. L.
Published: October 2005

Six-monthly serial data from 224 children aged 4–18 years include puretone auditory thresholds, noise exposure, otological histories, and data relating to body size and maturity. Otological abnormalities in these “normal” children may be associated with higher auditory thresholds. Also auditory thresholds are related negatively to stature and levels of sexual and skeletal maturity. The girls have slightly lower thresholds than the boys; this sex difference is larger in the older children and the median total noise exposure scores are considerably higher for boys than girls in the older groups indicating noise exposure may adversely affect hearing ability. Furthermore, in the older groups, especially boys, the six-monthly increments are larger, in the direction of hearing loss. The noise exposure data indicate specific important sources of noise. [Work supported by U.S. Environmental Protection Agency and the Aerospace Medical Research Laboratory.]
Toward a theoretically based DRC for impulse noise
Authors: Price G. Richard
Published: October 2005

The presently accepted damage-risk criterion for impulse noise [CHABA. Rep. WG-57 (1968)] makes no specific allowance for the spectral tuning of the ear. Data from the cat ear, reported at the 9th ICA (G. R. Price, 1977), indicate that the stapes displacement at the threshold of loss for spectrally simple impulses declines as a function of frequency at about 6 dB/octave. Assuming a similar pattern to hold for the human ear, a curve relating the free-field peak pressure levels of gunfire impulses to the threshold of loss has been developed. The curve allows progressively less pressure (−3 dB/octave) as the spectral peak of the impulse rises to the midrange and allows increases in pressure if the spectral peak is higher than that. For the low-frequency impulses (most gunfire) this is the opposite of the CHABA prediction. Validation with experimental ears and weapons impulses remains to be done.
Longitudinal changes in auditory sensitivity in laboratory subjects
Authors: Cushing E. Marion , Ward W. Dixon
Published: October 2005

Audiometric records of some 60 student subjects in our noise exposure experiments, who had been exposed twice a week, for periods of time ranging from 3 months to 3 yr, to noise doses severe enough to produce 10 to 30 dB of TTS2 (auditory fatigue measured 2 min after exposure), were examined for long-term effects. The median of the first three daily pre-exposure audiograms of each subject was compared to the last three and the differences analyzed. Although an apparent grand mean decrease in sensitivity of about 2 dB was found, all test frequencies (0.25–8 kHz in half-octave steps) showed the same change, which indicates that the shift was a behavioral one rather than a real loss of auditory sensitivity; that is, there was no greater change at 2.8 or 4 kHz than at any other frequency. Examination of individual records showed an essentially random pattern of shifts. Thus under the conditions of our experiments, in which full audiometric recovery occurs between successive exposures, no cumulative effects seem to be occurring. Results do not support the microtrauma hypothesis. [Research supported by the National Institute for Occupational Safety and Health, Public Health Service.]
Effective intensity of interrupted wide-band noise
Authors: Viemeister N. F. , Widin G. P.
Published: October 2005

Previous observations have suggested that for modulation frequencies above 2 kHz, detection of sinusoidal amplitude modulation of wide-band noise is based upon detection of an increase in average power produced by adding modulation. The present experiments using pulse-modulated (interrupted) noise further support this suggestion and indicate an auditory analogy to the Talbot-Plateau law of vision. Specifically, at interruption rates for which the temporal fluctuations are essentially “fused”: (1) discriminability between 250-msec bursts of modulated and unmodulated noise is minimal when the average power of the waveforms is equal; (2) the thresholds for detection of an unmodulated noise signal masked by either modulated or unmodulated noise are identical when the average power of the maskers is equal. The effects of interruption rate, duty cycle, and the role of short-term spectral cues will be discussed. [Research supported by NIH and by NSF.]
Choice reaction time to intensity increments in continuous white noise
Authors: Widin Gregory P. , Viemeister Neal F.
Published: October 2005

Measurements of choice reaction time (RT) to a 100 msec increment in continuous noise were obtained as a function of noise level and signal-to-noise ratio. Hit latencies are generally shorter than those for correct rejections. Under accuracy instructions, for both hits and correct rejections, RT monotonically decreases with increasing signal-to-noise ratio, but constant signal-to-noise ratio yields constant mean latency, indicating the applicability of Weber's law with RT as dependent variable. This constrast with the results of Raab and Grossberg for type-d HT [J. Exp. Psychol. 69, 609–612 (1965)]. Under speed instructions, and with mean RT's between 100–150 msec, d′ increases with increasing signal-to-noise ratio, but is approximately constant at fixed signal-to-noise ratio, again in accordance with Weber's law. [Research supported by NSF and NIH.]
Binaural frequency selectivity measured with a central masking paradigm
Authors: Tucci D. L. , Calder H. B.
Published: October 2005

Central masking was employed to investigate frequency selectivity of the binaural auditory system. Using a Bekesy adaptive procedure, four subjects were required to maintain a masker intensity such that a constant-intensity signal presented to the contralateral ear was just detectable. Several masker frequencies were investigated adjacent to the signal frequency in order to generate binaural “psychophysical tuning curves” for signals of 500 and 1000 Hz. Signal duration was 50 msec inclusive of 20 msec rise and fall times. The signal intensity was fixed at 3, 8, or 11 dB SL. The pure-tone masker was gated repeatedly with a duty cycle of 50% and a duration of 250 msec. The signal and masker were presented concurrently, with the masker onset preceding the signal onset by 20 msec. Results showed the asymmetric masking pattern characteristic of previous psychophysically and physiologically derived tuning curves. The functions displayed steeper slopes for maskers above the signal frequency. However, functions obtained in this study generally had steeper slopes than functions reported in previous psychophysical investigations of monaural frequency selectivity.
Ultra-audiometric hearing among the “profoundly deaf.”
Authors: Berlin Charles , Berlin Harriet , Halperin Henry , Wexler Kathy , Smith Sharon
Published: October 2005

We recently reported an unusual audiometric configuration in a woman misdiagnosed as having “an hysterical hearing loss” in which she detected 12 000 Hz signals at 45 dB SPL. In a series of tests, we uncovered a sizeable percentage of deaf people who have better hearing above than below 8000 Hz. Virtually all these people have unusually good speech considering the amount of loss in the so-called speech frequencies. We will present speech samples with audiograms and postulate the following: (1) Zero dB HL for 12 kHz is approximately 25 dB SPL; (2) an audiometric configuration such as demonstrated by these patients permits (a) a modicum of sensitivity to transients in the field (but not from frequency limited hearing aids); (b) time-code perception for broadband signals, and (3) may give-the patient considerable access to temporal monitoring of speech especially with sibilants and plosives. At present we have no idea of the etiology of these hearing losses; a companion paper will describe a translating hearing aid we built for two patients and discuss some of our experiences with the aids. [Supported by NIH, DRF, and The Kresge Foundation.]
Temporal integration in dysphasic children
Authors: Hochman Renee , Thal Donna , Maxon Antonia
Published: October 2005

The issue of a speed constraint on the auditory processing of dysphasic children [P. Tallal and M. Piercy, Neuropsychologia 13, 69–74 (1975)] was reexamined in our study of temporal integration in seven dysphasic children. Temporal integration was indirectly measured in terms of increases and decreases in intensity required for threshold responses to 1000 Hz stimuli of varying durations (20, 200, and 500 msec). Threshold-duration functions were plotted and mean threshold shifts were computed, reflecting the differences in intensity required to perceive the 200 and 20 msec stimuli. All of the dysphasics responded to both the long and short duration stimuli. A mean threshold shift of 18.11 dB was observed in the dysphasic children. The mean threshold shift of the dysphasic subjects was not significantly different from the 15.72 dB mean threshold shift observed in normal children [A. Maxon and I. Hochberg, J. Acoust. Soc. Am. 61, S88(A) (1977)] for a tenfold duration change. In conclusion, normal temporal integrative functioning was found in the dysphasic subjects, indicating an ability to use short duration information.
Analytic versus synthetic perception of complex tones
Authors: Burns Edward M. , Houtsma Adrianus J. M.
Published: October 2005

The ability of observers to track the pitch of individual harmonics of a complex tone (analytic perception) confounds interpretation of the results of many experiments on fundamental tracking of complex tones (synthetic perception). This is particularly true for 2AFC paradigms and makes pitch discrimination results for complex tones difficult to interpret. Data are presented which illustrate this problem. In one experiment observers were required to detect a change in the (missing) fundamental of a “complex” tone comprising one, two, or three harmonics in a 2AFC task. Half of our observers produced results equivalent to those of Houtgast [J. Acoust. Soc. Am. 60, 405–409 (1976)] except that our results were independent of S/N ratio. Houtgast argued for the existence of subharmonic pitch cues. We propose an interpretation based on comparisons of harmonics of stimulus tones. Another 8AFC musical interval identification experiment using tone complexes of non-successive harmonics shows also the confounding effect of harmonic tracking. [Work supported by NIH.]