bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Frequency and Intensity Anchors on Both Pitch and Loudness Judgments
Authors: Pierce Linda
Published: October 2005

The effects of an extreme anchor stimulus were compared for pitch and loudness judgments. The cross-continua effects of an extended range were also examined by using a two-dimensional stimulus context. Subjects rated both the pitch and loudness of pure tones on two seven-point category scales in each of three conditions. All subjects heard all combinations of a set of pure tones at five frequencies between 1000 and 2000 Hz and five intensities between 40 and 60 dB above threshold. One group of subjects heard only these 25 stimuli. Two groups also heard and rated extreme stimuli: one group received a higher-frequency tone (3800 Hz) at median level every sixth stimulus and the other group received a tone at greater level (75 dB above threshold) at median frequency every sixth stimulus. For their corresponding dimensions, the effect of the extreme stimulus in level was greater than that for the extreme stimulus in frequency. However, the frequency anchor reduced discriminability among the levels without a corresponding effect for the sound-pressure-level anchor on the pitch judgments. These results were attributed to two factors: the quantitative character of loudness versus the qualitative character of pitch and the relative distances of the two anchors from the other stimuli on the corresponding dimension.
Sort Board for Random Access of Auditory Stimuli
Authors: Coker Cecil H. , Pruzansky Sandra
Published: October 2005

An apparatus is described that allows subjects to initiate presentation of auditory stimuli at random and to sort, rank, or otherwise arrange the stimuli in a two-dimensional array. The system consists of (1) a square board with 256 holes; (2) a set of up to 36 freely movable control pegs; (3) a general-purpose DDP-516 computer; (4) a random rapid-access disk. When a subject presses down on a peg placed in any of the holes, the computer identifies the peg and presents an auditory stimulus. In a pilot study using this system, subjects were asked to arrange two-parameter complex tones so that proximity of pegs on the board reflected similarity. The tones were stored on disk in digital form. The computer identified the peg, retrived from disk the stimulus assigned to that peg, and updated a CRT display containing an image of the board and the location of each peg at last operation. A chronological history of the subject's performance, including the sequence of stimulus presentation, location of the peg at each operation, and the interval between successive stimulus presentations, was recorded on digital tape.
Intensity Characteristics of Mechanoreceptors
Authors: Zwislocki J. J. , Adams W. B. , Kletsky E. J.
Published: October 2005

According to recent detailed recordings of neural firing rates, the intensity characteristics of auditory and other mechanoreceptors closely approximate the input-output function of an rms detector. This becomes particularly clearly evident when the stimulus consists of a sinusoid added to random noise. The characteristic remains the same for both extrinsic and intrinsic noise. It can be expressed by means of a simple equation that contains no free constants. The rms properties of auditory receptors appear to be reflected in psychophysical experiments that deal with monaural and central masking, signal detection as a function of duration, and loudness. In spite of great similarities, the mechanoreceptors should not be considered as true rms detectors, since they show some phase sensitivity. The difference can be ignored, however, under many experimental conditions.
Sensitivities in Absolute Identification, Magnitude Estimation, and Category Scaling
Authors: Braida L. D.
Published: October 2005

“Preliminary Theory of Intensity Resolution” [N. I. Durlach and L. D. Braida, J. Acoust. Soc. Amer. 46, 372–383 (1969)] predicts that the same set of sensitivities applies to absolute identification, magnitude estimation, and category scaling, when the same set of stimuli is used in all three paradigms. This paper describes experiments designed to test this prediction. In all cases, the stimulus set consisted of ten tone pulses, differing only in intensity, which were spaced by equal-decibel increments. While the sensitivity measures obtained for identification and category scaling were in close agreement, sensitivity in magnitude estimation was less than in the other paradigms. The form of the cumulative sensitivity functions obtained was essentially logarithmic for all paradigms, but the dependence of total sensitivity upon total intensity range was different for magnitude estimation than for the other paradigms. The data suggest that magnitude estimates were made relative to a large fixed context of sounds, while in the other paradigms the judgmental context was adjusted to the range of intensities presented. [Work supported principally by the National Institutes of Health and in part by the Joint Services Electronics Program.]
Dichotic Summation of Loudness over Time
Authors: Scharf B. , Weissmann S. M.
Published: October 2005

The loudness of two 5-msec tone bursts, presented dichotically, was measured as a function of the temporal separation, ΔT, between the onset of the burst in one ear and the onset in the other ear. Measurements were made at 40, 70, and 90 dB SPL. Over-all loudness did not change as ΔT was increased from 0 msec (when the signal was binaural) to about 10 msec. Beyond 10 msec, the loudness decreased steadily until, at a ΔT greater than 200 msec, the two bursts were no louder than either alone. Similar results were obtained with 5-msec bursts of white noise. These results also resemble those obtained with monaurally presented tone bursts. However, the absence of peripheral adaptation in the dichotic presentation may account for some differences between the dichotic and monaural results. For example, whereas summation between two monaural bursts decreases at high levels, summation between two dichotic bursts is independent of level. [Research supported by a grant from the National Institute of Neurological Diseases and Stroke.]
Effect of Increments in a Sinusoidal Pedestal on the Vertex Potential
Authors: Nichols T. L. , Tanenholtz S. D.
Published: October 2005

The averaged auditory evoked potential (measured from vertex to earlobe) was obtained under several conditions of pedestal-plus-increment stimulation. The pedestal was a 1000-Hz sinusoid presented to human subjects at either 50, 60, or 70 dB SPL. The increments were 100 msec bursts of the same 1000-Hz sinusoid. The increments were presented at 3-sec intervals, and ranged from 1 to 12 dB above each pedestal level. The functions relating log (N1−P2) to ΔI were of the form described by A. Davis, C. Bowers and I. Hirsh for noise-masked sinusoidal pips [“Relations of the Human Vertex Potential to Acoustic Input: Loudness and Masking”, J. Acoust. Soc. Amer. 43, 431–438 (1968)], but were much steeper. Increments of 2 dB resulted in N1−P2 potentials of 6μV, and increments of 12 dB resulted in N1−P2 potentials of 13μV. Virtually the entire dynamic range of the auditory evoked potential was accounted for by a 12-dB change in stimulus and most of the range was accounted for by the first 6 dB.
Dynamical Model for Ultrasonic Shear and Compressional Relaxation in Liquids
Authors: Litovitz T. A. , Montrose C. J.
Published: October 2005

Ultrasonic studies in liquids have shown that shear and structural relaxation processes can not generally be described in terms of a simple rate or single relaxation process. In this paper, we present a physical model for the structural dynamics of liquids in terms of which both the shear and compressional relaxation time spectra are calculated. The model relates the strain dynamics of the liquid to fluctuations in an ordering parameter characterizing the local liquid structure. The kinetics of the ordering parameter are assumed to be governed by the combined effects of a simple rate process and diffusion. The predictions of the theory for the frequency dependence of the compressibility and rigidity are in quite good agreement with data in a number of liquids. [This work was supported in part by the Atomic Energy Commission.]
Ultrasonic Absorption in Triethylamine-Water Solution near its Critical Solution Temperature
Authors: Yun S. S.
Published: October 2005

Ultrasonic absorption and velocity (1, 5, 10 MHz) in triethylamine-water binary liquid system were investigated through the critical solution temperature by means of the pulse-echo method. The results were obtained for the variation of velocity with temperature and also for the behavior of the attenuation near the critical point. For each frequency investigated, the absorption exhibited a marked maximum at the critical solution temperature similar to the results shown in the earlier work at 600 KHz [A. G. Chynoworth and W. G. Schneider, J. Chem. Phys. 19, 1566 (1952)]. However, the temperature dependence of the attenuation near the critical temperature is quite different from the observations made earlier at higher frequencies (1–9 MHz) [G. F. Alfray and W. G. Schneider, Discussions Faraday Soc. No. 15, 218 (1953)]. The differences between the present and the earlier work are compared and discussed. [The work was supported in part by an Ohio University Research Grant and a National Science Foundation Grant.]
Acoustic Shielding Properties of a Free-Standing Wall
Authors: Purcell Jack B. C. , Noppe Roger C.
Published: October 2005

Acoustical measurements have been conducted to determine the shielding properties of a free-standing wall 10 ft high and 120 ft long situated in an open field of black-top surfacing. The sound source (octave bands of noise) consisted of a high-level high-fidelity loudspeaker positioned at a number of multiples of the wall height on a centerline normal to the wall axis. The microphone was in turn placed at “mirrored” distances along the center line on the opposite side of the wall. Measurements were obtained for five source positions and five corresponding microphone positions for a total of 25 sets of measurements. A second series of measurements was performed identical to the first series but without the wall. Care was taken to maintain an identical source level. The excess attenuation was determined by comparing the data obtained in the two test series. The results indicate that significant deviations can be expected in the acoustic-shielding properties of a wall from data previously reported in the literature.
Speech Perception in Classrooms
Authors: Kingsbury H. F. , Strumpf F. M.
Published: October 2005

The acoustical conditions in classrooms of increasing size frequently result in poor speech intelligibility. Speech intelligibility is a function of several variables of which speech level (vocal effort), background noise level, and acoustical design characteristics are perhaps the most important. This report discusses the influence of these stated factors on speech intelligibility in three different rectangular classrooms of varying size and design characteristics. Speech intelligibility for the varying conditions wa determined by use of the modified rhyme test (MRT). The articulation index was also computed for the various signal-to-noise levels used in the tests. Data are presented in the form of computer-drawn contour maps showing noise distribution and speech intelligibility in the rooms. [The work being reported was supported by a grant from the U. S. Office of Education.]
Signal Processing to Reduce Multipath Distortion in Small Rooms
Authors: Flanagan J. L. , Lummis R. C.
Published: October 2005

The transmission between a sound source and a microphone in a small hard-walled room is characterized by multiple peaks and sharp valleys. Sound received by such a microphone often is judged to be undesirably distorted or spectrally colored. A technique is described for combining the signals from two or more microphones to produce a single output having less multipath distortion than any of the individual microphone signals. The output from each microphone is filtered to separate it into a number of bandpass signals occupying contiguous frequency bands. The microphone with greatest long-time response in a given frequency band contributes that band to the output. Each microphone, then, is used only for those frequency bands in which its response is greater than any other microphone, so that the combined output contains less spectral coloration than the signal from any individual microphone. The performance of the process was studied by simulation on a digital computer, and sample recordings are included.
Model for the Determination of the Size and Orientation of Reflectors from Ultrasonic Frequency Analysis
Authors: Whaley H. L. , Adler L.
Published: October 2005

Experiments were carried out which determined the dependence of spectral variations in a reflected ultrasonic pulse on the size, shape, and orientation of the reflector. A widebanded ultrasonic pulse was used, and reflectors consisted of the flattened ends of metal rods immersed in water and machined discontinuities in metal blocks. The distributions of spectral energies of such pulses are influenced by the angular orientation and size of the reflector, but not by its specific acoustic impedance. An analytical model is developed, which assumes that interference of the waves received from the extremes of the reflecting surface is responsible for the variations of the received frequency spectrum. An expression is derived that accounts for the measured frequency variations in terms of size and three-dimensional angular orientation of the reflector, water path, and off-axis alignment. The experimental results are explained very well by this model. It has been shown also that the method can be used successfully to characterize hidden defects in metals. [Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corporation.]
Interruptibility of Speech
Authors: Ladefoged Peter , Silverstein Raymond O.
Published: October 2005

We have conducted a preliminary set of experiments on the ability of a speaker to interrupt himself when given a cue to do so at unexpected moments. Subjects were asked to repeat short utterances, each containing only one primary stress, at a fixed rhythm determined by a metronome. Contrary to our expectations, we did not find any particular point in these utterances when a speaker finds it harder to stop saying what he originally intended to say and start saying something else instead. Subjects were able to respond about 350 msec after the presentation of the cue (a 1-kHz tone), irrespective of where in the utterance the cue was presented. But when the cue was presented not within but just before the utterance, subjects took far longer (up to 750 msec) to respond. It is hypothesized that while a speaker is planning the articulations for a short utterance (in this case a single stress group), there is a period during which he cannot readily plan another utterance. [Research supported by ONR.]
Significance of Intra- and Intersentence Pause Times in Perceptual Judgments of Oral Reading Rate
Authors: Lass Norman J.
Published: October 2005

The purpose of this investigation was to determine if alterations in intra- and intersentence pause times in an individual's recorded reading of a standard prose passage (with no changes made in speech time) would result in alterations in perceptual judgments of his oral reading rate. Intra- and intersentence pause times were manipulated in one of the following ways: no change; 25% increase; 25% decrease; 50% increase; 50% decrease; 75% increase; 75% decrease. Electronic reproductions of the original tape recording were made; the removal or addition of pause time was accomplished in all cases by the removal or addition of the appropriate percentages of actual tape at each pause point. The original and pause-altered recordings were arranged in random order on a master tape and played to a group of 78 judges for rate evaluations using an equal-appearing intervals scale. Results of listener evaluations indicate that pause time is an important variable in perceptual judgments of oral reading rate. [Research supported by the National Institute of Neurological Diseases and Blindness.]
Innervation of the Cochlea
Authors: Smith Catherine A.
Published: October 2005

Recent physiological studies have raised questions regarding the validity of previous anatomical information on the afferent innervation of the organ of Corti. Important questions are: What is the relative number of nerve fibers to inner and outer hair cells? How long a segment of basilar membrane is innervated by a single fiber? Is there any dichotomy of fibers to inner and outer hair cells? These and other questions are considered in the light of past and recent studies. The pathways and terminals of the efferent olivocochlear tract have been well defined in some animals. For example, the well-documented concentration of efferents in the basal two-thirds of the guinea pig cochlea has been confirmed in the chinchilla but the number of efferents per outer hair cell is less in the latter animal. Our (Iurato and Smith) recent studies have shown that the outer hair cells are innervated for the most part by the crossed efferents whereas the inner spiral bundle is mostly, if not entirely, derived from the homolateral tract. An analysis of the sensory structure and innervation of the bird's basilar papilla (Takasaka and Smith) have revealed some parallels in terminal efferent fibers between pigeon and rodents. The large efferent findings associated with well-developed subsynaptic cisternae are found only in a particular location and on a differentiated type hair cell.
Relations Among the Various Single-Number Ratings of Environmental Noise
Authors: Schultz T. J.
Published: October 2005

This paper reviews 15 rating scales or procedures currently used in this country and in Europe, for the evaluation of noise in terms of the corresponding subjective response. The family relations among these ratings are shown and some psychoacoustical reasons are given for the frequently noted fact that, despite apparently great differences in the formulations of these ratings, they show high correlation among themselves when applied to a large variety of noise spectra.
Office Machine Quieting
Authors: Eisner Mark
Published: October 2005

Noise problems occur when machines that type, punch, duplicate, etc., are installed in large office areas. These office areas are staffed primarily by women who operate the machines. The noise levels generated by the machines may be high enough to make speech unintelligible and telephone usage difficult. In addition, the people working in a noisy environment may become annoyed. This annoyance often causes absenteeism and high staff turnover, which may result in inefficient and uneconomical operation. A 6–10 dBA reduction in noise levels can be achieved by treating the covers of the machines with damping compound and sealing openings that transmit the sound generated by the operating mechanism. This noise reduction does not affect the performance of the machine.
Ultrasonic Absorption Measurements in Napthalene Single Crystals at Low Temperatures
Authors: Wilson J. D. , Yun S. S.
Published: October 2005

The attenuation of ultrasonic waves was measured in single crystals of napthalene at frequencies from 15 to 45 MHz over a temperature range from 23°C down to −180°C. The absorption was anomalously high at low temperatures (−140°–−170°C), and a maximum occurred in this temperature region for all frequencies. The peak was observed to shift to a higher temperature with increasing frequency. These phenomena are compared with the temperature dependence of the absorption coefficient of organic crystals in terms of the Liberman resonance absorption theory [L. N. Libermann, Phys. Rev. 113, 1052 (1959)]. Experimental evidence from other organic crystals has supported the predicted high absorption; however, the peak had not been previously observed. [The work was supported in part by an Ohio University Research Grant and a National Science Foundation Grant.]
On Obtaining Transition Rates from Sound Absorption and Dispersion Curves
Authors: Shields F. Douglas
Published: October 2005

The problem of obtaining transition rates from acoustic measurements of vibrational relaxation times is discussed. The error involved in using the Schäfer equation, τ1 = τC1/Σ1C1, to obtain the relaxation times for a single mode from the measured relaxation time is evaluated by calculating the sound absorption and dispersion from the reaction equations using the method of Tanczos. The analysis shows that the absorption and dispersion curves closely approximate the single-relaxation-time curve in a series relaxation process as long as the v-v transfer is at least as fast as the v-t transfer. The calculations rule out a v-v process for the CO2/H2O interaction. [This work was supported by the U. S. Office of Naval Research.]
Sound Measurements in Fluid in the Vicinity of the Critical Point
Authors: Carome E. F. , Fritsch K.
Published: October 2005

Measurements of the velocity of sound in fluids at frequencies in the low kilohertz range are being made using resonant cavity techniques. Both condenser microphones and piezoelectric plates are being used as sources and receivers in this work. Data obtained recently in carbon dioxide and sulfur hexafluoride will be used to illustrate the application of this method in the study of the behavior of fluids in the vicinity of critical points. [Supported in part by the Office of Naval Research and NASA.]
Traveling Wave Reflection Methods for Measuring Ultrasonic Attenuation in Thin Rods and Wires
Authors: Papadakis Emmanuel P.
Published: October 2005

Two methods are outlined for determining the ultrasonic attenuation in thin rod-shaped specimens bonded to wire transmission lines. One method involves digital (video) pulses or short rf bursts resulting in separated echoes. The other employs rf bursts longer than three round trips in the specimen, resulting in overlapped (stepped) echoes from the specimen. Use of three echo amplitudes or the amplitudes of three interference steps permits the calculation of the reflection coefficient R at the transmission line/specimen junction and the attenuation coefficient α in the specimen. Formulas are given for R and α. Illustrative experiments are described.
Design and Construction of the NEFBRACS Line Transducer
Authors: Smith D. A.
Published: October 2005

NEFBRACS is an acronym for nearfield bearing and range accuracy calibration system. The success of NEFBRACS depended upon the design and construction of a horizontally mounted, especially shaded, 22-ft-long line transducer. The transducer was to generate a cylindrical wave in the region to be occupied by the sonar system transducer under test. A computer program was developed for computing the field pressure amplitude and phase, so that optimum shading coefficients could be chosen. One of the most difficult construction problems was the horizontal mounting of 31 elements; the mounting had to be transparent, yet strong enough to support itself with negligible bending. The finished line comprises 31 PZT-4 cylinders, 12 × 12 × 18 in. thick. Corprene plugs were inserted into the center of each element and the element put in Scotchcast 221. The finished element was a 34 × 34-in. cylinder. The elements were inserted in RHO-C rubber “spiders,” which were in turn mounted in a 22-ft-long, 6-in.-diam, expanded metal pipe. The line behaves as a line of point sources to within measurement accuracy.
Acoustic Radiation from Multiple Surfaces
Authors: New Ronald
Published: October 2005

A significant part of the current research effort in Acoustic Radiation Theory is concerned with transducer arrays and the effects of the interaction therein. There exist two broad subclasses of the total problem: (1) one or more vibrating elements on a single common surface (baffle) and (2) one or more vibrating elements on multiple surfaces. Problems within the first subclass have been treated extensively. Few solutions exist for problems within the second subclass and those that do are very restricted. This exposition seeks to extend the list of analytic developments to include solutions to certain multiple surface problems. Initially, we obtain a formal solution to the problem of two vibrating spheres using the method of Green's functions. The extension to N vibrating spheres, or arbitrary radii and location, follows and is obtained directly from the two-sphere problem. It is shown that the method is generally applicable to the N-body problem if the individual body shapes conform to a “separable” coordinate system and the total field can be made to satisfy the Sommerfeld radiation condition.
On the Temporal Organization of Syllabic Processes
Authors: Lindblom B.
Published: October 2005

With respect to temporal phenomena, human speech production exhibits many complex but lawful patterns. There can be little doubt that during the production of an utterance, the nervous system accomplishes its task with great precision and a high degree of automacity. An understanding of pronunciation and its temporal organization is an urgent goal both in the fundamental study of language and speech and in various applications. The purpose of this paper is to contribute towards assessing our present knowledge about temporal mechanisms in speech. Special attention will be devoted to the work of Chistovich and Kozhevnikov. These investigations suggest the interpretation of the classical notion of the syllable as a mechanism of articulatory programming upon which higher-level mechanisms of “rhythm generation” operate and within which temporal relations between successive gesture initiations are controlled. The present review discusses available evidence in terms of this conceptualization. Examples will be given of mechanisms of “intersyllabic” timing such as, for instance, synactic processes, syllabic structure, and segmental shape and mechanisms of “intrasyllabic” timing such as those underlying the synchronization of phonatory and articulatory events, articulatory coordination, and coarticulation and the acoustic duration of vowel and consonant segments.
Perception of Temporal Phenomena in Speech
Authors: Huggins A. W. F.
Published: October 2005

The perceptual results of altering segment durations in speech fall into two classes: (1) those in which the identity of the utterance changes and (2) those in which the naturalness of the utterance changes. (Note that grossly unnatural speech may be incomprehensible.) Experiments of both the foregoing types will be reviewed, and some new results will be presented on temporal compensation in perception—that is, on how a subliminal change in the duration of one phoneme affects the perceived duration of an adjacent phoneme. [This research was supported in part by the Science Research Council (U.K.) and in part by NINDB grant.]
Attempts to Condition the Acoustic Reflex
Authors: Bates Marjorie Anne , Loeb Michel , Smith Richard P. , Fletcher John L.
Published: October 2005

Using a delay conditioning paradigm, an attempt was made to condition the acoustic reflex, as produced by a 1000-cps tone, to onset of a light. Responses were measured in humans with an acoustic impedance bridge. Two out of 12 Ss gave obvious anticipatory conditioning responses; four other Ss also gave anticipatory reactions, but there was some doubt concerning these results. The remaining six Ss failed to condition. Application of the results are discussed in connection with protection from noise and future lines of research are suggested.
Vibrational Holography of the Tympanic Membrane: Further Findings
Authors: Tonndorf Juergen , Khanna Shyam M.
Published: October 2005

At the 78th Meeting, photographs of the vibratory pattern of the tympanic membrane were presented [Khanna et al., Tonndorf and Khanna]. They were obtained with the aid of time-averaged holography from cadaver ears of cat and man. These findings, which are compatible with the catenary principle of tympanic membrane action as postulated by Helmholtz (1868), need further elaboration. With frequency above 2000 Hz, the patterns become gradually restricted in area and subdivide into multiple quasi-independent subpatterns. Volume displacements for constant SPLs calculated from such photographs decrease with frequency in a similar manner and were found to be in excellent numerical agreement with such values calculated from available impedance data obtained in living animals or human subjects. This latter agreement (1) justified the use of cadaver material in the present experiments and (2) shows that the multiple subpatterns at higher frequencies are still in phase over the entire surface of the tympanic membrane. (Time-averaged holography is not sensitive to phase.) A revised formulation of the total middle-ear transformer ratio, which includes the catenary effect, is presented. [Supported by NIH grants.]
Mössbauer Effect Studies of the Middle Ears of Guinea Pigs, Cats, and Frogs
Authors: Taylor K. J. , Johnstone B. M.
Published: October 2005

The Mössbauer effect has been used to measure transfer characteristics of the middle ears of guinea pigs, cats, and various species of frogs. These show a remarkable similarity to each other in form and efficiency up to about 8 kHz. All have a roll off at about 6 dB/oct at low frequencies, but even up to 30 kHz neither the guinea pig nor the cat shows a roll off, which could be expected to occur as a result of the mass of the system becoming significant in the impedance. All the ears examined show a resistive type transmission loss of at least 15 dB and from these results it would seem that the detail of the structure of the middle ear is unimportant to the efficiency. These results are significantly different from those obtained by impedance measurements and offer a more rigorous basis from which to analyze middle-ear function.
Increase in Cochlear Cell Damage as a Function of Variations in Exposure to “Acid Rock” Music
Authors: Lipscomb David M.
Published: October 2005

Fourteen guinea pigs were variously subjected to high-intensity rock music peaking at 122 dB SPL. During the stimulation periods, the music was interrupted for 1 min every 4 min to approximate the intermittent exposure occasioned at discotheques. Total exposure time ranged from no exposure to 80 h. Surface preparations of the cochlear tissue were prepared and underwent phase-contrast microscopic inspection. As anticipated, the amount of cell damage increased as a function of increase in exposure time. For example, an ear exposed to the stimulus for a total of 5 h sustained damage to 1.73% of the total cell population. For an ear exposed for 45 h, 1.95% of the cells were damaged. After 80 h of intermittent exposure to the intense music, however, 7.57% of the cell population was found to be irreversibly destroyed, demonstrating a nonlinear growth in cochlear cell damage with increased exposure duration. An important fact is noted in that cell destruction discovered in response to the acoustically complex stimulus was greater at the apical region of the cochlea with gradually lessening amounts of damage noted in specimens removed from lower coils. Numerous phase-contrast photomicrographs illustrate the patterns of cell damage caused by the sound stimulus. The results of this study are compared to an earlier report which had noted more widespread cell damage.
Finite and Small Amplitude Underwater Gas Bubble Oscillations Compared
Authors: Epstein David
Published: October 2005

Bubble oscillation is well described by the nonlinear Keller-Kolodner equation. Although compressibility effects, which strongly influence the motion, are considered, analysis starts with incompressible approximation. The key parameter is p1/p0, the ambient/bubble pressure ratio. This ranges from zero to unity; near the lower limit finite amplitude pulsations occur; near the upper, simple harmonic motion ensues. The equation determining the maximum and minimum bubble radii, with p1/p0 as parameter, is graphed; these endpoints coalesce at a level where p1/p0 = 1. Further, taking compressibility into account, at each depth the end-points also converge to an equilibrium radius. T̄ has a simple power law dependence on p1/p0; this is generally not true for the finite amplitude period T1. The curves for T̄ and T1, as calculated from the Willis formula, cross; hence the actual T1 vs depth may be inferred. The shape of the bubble radius vs time curve changes from pulsation to simple oscillation with depth; this is asymptotically correct at any level, since T1 → T̄.
Rectified Diffusion under Adiabatic Conditions
Authors: Fogler H. S. , Verma V. K.
Published: October 2005

The theoretically predicted bubble growth rate for rectified diffusion under isothermal conditions is much lower than the rate found experimentally by Eller [J. Acoust. Soc. Amer. 46, 1246 (1969)]. The assumption of isothermal condition can only be justified for infinite thermal diffusivity. For real gas bubbles, however, the thermal condition lies between the isothermal and adiabatic limits. Our analysis was undertaken to establish the adiabatic limit. Contrary to the case of isothermal collapse, wherein the increased pressure (hence the surface concentration) can only result in an outwards diffusional flux, the solubility inversion effect for gases can cause first inwards and then outwards diffusional flux during the same phase of adiabatic collapse. In particular, when the heat of solution, ΔH0, of the gas is less than −(νBT0)/(ν − 1), where ν = Cν/Cr, and B is the gas constant, the diffusional flux changes direction as mentioned above at RR0=[(νν − 1)(BT0−ΔH0)]13(ν − 1). This flux reversal can cause the bubble to grow much faster than in the isothermal case.
Singular Perturbation in Acoustic Cavitation
Authors: Skinner L. A.
Published: October 2005

Approximate solution of a model ordinary differential equation problem illustrates essential ideas in a new approach to acoustic cavitation theory. Rectified diffusion bubble growth through resonance size has been analyzed for the first time. This is a singular perturbation problem. The asymptotic expansion appropriate for the thin boundary layer of concentration oscillation effects is not uniformly valid. Details of the resonance domain, which is characterized by relatively rapid growth, are discussed. This work is based on a previous paper dealing with cavitation threshold [J. Acoust. Soc. Amer. 47, 327–331 (1960)].
Real-Time Acquisition and Analysis of Acoustic Propagation Data at Sea
Authors: Lowenstein Carl D.
Published: October 2005

A system for the analysis of acoustic signals from both transient and continuous sources has been developed for installation aboard the research platform FLIP. The system is built around a Digital Equipment Corporation PDP-8/I computer. A six-channel A:D converter allows simultaneous sampling of six hydrophone channels. The data are transmitted to core storage, and thence to an intermediate magnetic tape. The computer performs spectral analyses using the fast Fourier transform algorithm. Averaged spectrum values can be recorded on tape for later plotting, or displayed in real time on a cathode-ray tube. [This report represents the results of research sponsored by the Office of Naval Research.]
Two-Mass Model of the Vocal Cords
Authors: Dudgeon D. E.
Published: October 2005

Early vocal system models consisted essentially of a pulsating source, which was used to drive a time-varying filter representing the vocal tract. A later model attempted to parallel the human vocal system more closely by including a mechanical (mass-spring) oscillator, representing the vocal cords, driven by feedback within the vocal system model. This provided a self-excited source for driving the vocal tract analog, bringing speech synthesis and human speech production closer together. The two-mass vocal cord model is a slightly more complex version of the mechanical oscillator, and is designed to incorporate more phenomena observed in human vocal cords by high-speed motion picture techniques. This slight increase in complexity enables even closer analogies between synthetic and human vocal systems. In particular, experiments with this model show that it can sustain phase differences in the displacements of the upper and lower edges of the vocal cords as do the human vocal cords. Other experiments with the two-mass model indicate that there are a range of frequencies at which the vocal cords cannot be driven by the feedback system. These frequencies are related to the natural frequencies of the vocal tract configuration.
Vocal Fold Length Characteristics Associated with Modal, Falsetto, and Varying Intensity Phonations
Authors: Brown W. S. , Hollien Harry
Published: October 2005

Previous investigations concerned with the characteristics of vocal fold lengthening during changes in fundamental frequency have used relatively large intervals among the phonated frequency levels. Also, only limited data exist for vocal fold length associated with the falsetto voice—or as a function of vocal intensity. The present study, by means of conventional laryngeal photography, furnished vocal fold length data (1) associated with small frequency increments (semitone steps) both for the modal and falsetto registers and (2) as a function of vocal intensity. Based on the obtained data, the following conclusions appear tenable: (1) As expected, the vocal folds become longer as f0 is increased in semitone steps within the modal register. However, this variation is neither linear nor smooth; indeed a “stairstep” function (with occasional reversals) most closely typifies this trend. (2) For the limited number of samples studied, variations of vocal intensity appear to have little affect on vocal fold lengthening. (3) For the two subjects on which falsetto data were obtained, different patterns of vocal fold lengthening occurred.
Comparison of Sustained Vocal Fry and Terminal Breath Group Phonation
Authors: Shipp Thomas , McGlone Robert E.
Published: October 2005

The acoustic periods associated with sustained vocal-fry phonation and those characteristic at the termination of speech breath groups has led to the speculation that the two modes of phonation are similar. In the present study, simultaneously acquired measures of intrinsic laryngeal muscle activity, subglottal pressure, air flow, and the acoustic signal were compared for the same subject during the production of sustained vocal fry and at the ends of breath groups. Results showed that for the one subject studied sustained vocal fry and terminal fry phonation had highly similar patterns of laryngeal muscle activity, aerodynamic characteristics, and fundamental frequencies.
Role of the Cerebellum in a Speech Servosystem
Authors: Buxton Lawrence F.
Published: October 2005

Communication theorists have postulated the presence of a servosystem, utilizing negative feedback, underlying the speech process. The present paper discusses the role of the cerebellum as a regulator in such a servosystem. Because it receives, and sends, fiber tracts from all levels of the nervous system, the cerebellum may perform the three functions of the regulator: scanning, comparison, and correction. The cerebellum receives sensory information from activated muscles (scanning), integrates this data with information from sensory engrams (comparison), and sends information back to the cortex via thalamo-cortico fibers conveying data for compensatory movements to reduce the error signal (correction). The servosystem theoretically begins in the ideomotor center of the cerebrum, located in the supramarginal gyrus of the parietal lobe, which sends impulses to the motor and premotor cortex, with concurrent signals sent to the cerebellum via cortico-ponto-cerebellar fibers. The sensory engram, containing records of motor patterns, is discussed in terms of the predictive and damping functions of the cerebellum as an error-sensitive device that reacts to discrepancy between ordered state and realized state. Finally, the role of the cerebellum is discussed in terms of spatio-temporal function of sensory feedback for speech.
Investigation of Masking in the Cochlear Nucleus of the Cat
Authors: Pollak G. D. , Glaser E. M.
Published: October 2005

The behavior of averaged slow waves from the cochlear nucleus in response to tone bursts masked by narrow- and broad-band AM noise has been investigated in anesthetized cats. The results obtained when using narrow-band noise may be summarized as follows: (1) the noise was effective in masking the response to the tone only when located within a limited band of frequencies (MBW) around the tone frequency; (2) the MBW increased as the power of the tone frequency with an exponent of 0.69; (3) the MBW increased as the intensity was raised, with S/N held constant. When noise whose bandwidth significantly exceeded the MBW was used as the masking stimulus, the degree of masking was essentially the same as that produced by narrow-band noise of equal power, but whose spectrum was entirely within the MBW. This latter result seems contrary to what would be expected from critical-band theory considerations. It is suggested that, at least for the wide-band noise condition, the averaged slow-wave response may be a poor indicator of behavioral masking. [Research supported by the National Institutes of Health.]
Electrophysiological Studies on the Spatial Distribution of the Crossed Olivocochlear Bundle along the Guniea Pig Cochlea
Authors: Teas D. C. , Konishi T. , Nielsen D. W.
Published: October 2005

Changes in the electrical potentials in the cochlea were recorded at various locations along the cochlea, when the crossed olivocochlear bundle (COCB) was stimulated electrically on the floor of the fourth ventricle. Cochlear microphonic (CM) was recorded from Turns I, II, and III, and endocochlear potential (EP) from Turns I and III. Responses of the individual auditory nerve fibers were recorded in the modiolus. The site of the termination of these fibers could be ascertained by their best frequencies. Tetanic stimulation of COCB terminated 10 msec prior to the tone bursts. The effect of COCB stimulation on slow potentials in the scala media and augmentation of CM decreased as a function of distance between recording site and the round window. Decreases in discharge rate showed a wide variation among the fibers with best frequencies above 10 kHz. The greatest decrease in discharge rate was obtained in fibers with best frequencies between 7 and 9 kHz. Effectiveness of efferent stimulation on discharge rate of auditory fibers decreased gradually as their best frequencies decreased below 7 kHz. [This work was supported by the PHS.]
Responses of Single Cortical Cells to Repetitive Clicks
Authors: de Ribaupierre F. , Goldstein M. H. , Yeni-Komshian Grace
Published: October 2005

Intra- and extracellular recordings from single cells in the primary auditory cortex of unanesthetized cats were obtained using glass micropipets. Repetitive clicks were presented in trains of 500-msec duration. Over 100 units were systematically studied with click trains, single clicks, noise bursts, and tone bursts, presented 1/sec. 30% of the cells did not respond to repetitive clicks. These units did not respond to single clicks either, but responded to noise and/or tone bursts. 20% “followed” repetitive clicks with considerable scatter for rates up to 10–50/sec. Intracellular recordings from these cells showed stimulus-locked IPSPs for clicks. 30% followed repetitive clicks with precise locking with limiting rates of 10–1000/sec. These cells were “on” responders for tone and noise bursts and showed, when penetrated, a synchronization of EPSPs to repetitive clicks. The remaining 20% did not follow repetitive clicks but had click-rate-dependent responses, transient or sustained, to the trains. [Research supported in part by the National Institute of Neurological Diseases and Stroke and the U. S. Air Force Office of Scientific Research.]
Aircraft Noise Exposure Tradeoff Studies at Three Major Airports
Authors: Bishop Dwight E. , Horonjeff Richard
Published: October 2005

In a continuation of aircraft noise studies reported earlier, the relative effectiveness of three changes in aircraft operating procedures and aircraft hardware in reducing noise exposure around O'Hare International Airport—Chicago, John F. Kennedy Airport—New York, and Los Angeles International Airport were rated by determining the changes in land areas falling within noise exposure forecast (NEF) 30 and 40 contours. NEF contours for projected 1975 operations were calculated for changes, which included power cutbacks after takeoff and two segment approaches for all aircraft, and retrofit of current four-engine turbofan aircraft with either acoustically lined nacelles or with a “quiet” engine. Substantial reductions in land areas within NEF 30 and 40 contours occurred with retrofits and operational changes. Differences in effectiveness in reducing NEF contours between lined nacelle and “quiet” engine retrofits were moderate reflecting the increasing influence of noise from other aircraft on NEF values as four-engine turbofan aircraft noise levels are drastically reduced. [Work supported by the Federal Aviation Administration under contract.]
Acoustic Absorption in Some Composite Materials
Authors: Higgs R. W. , Eriksson L. J.
Published: October 2005

An experimental study was made of several absorber concepts utilizing composite material techniques. The sound velocities and absorption coefficients of lead wool-polyurethane composites and nickel-Cerrobend composites were measured as a function of composition, frequency, and pressure. The frequencies used ranged from 20–100 kHz and the composites were subjected to hydrostatic pressures ranging from 100 to 2000 psi during the measurements. It was shown that the absorption maximum occurs where the modulus is changing most rapidly with composition; at this composition, the absorption was most unstable with pressure. The theory of composites was applied to the moduli of the composites, and the agreement was quite good. A comparison of the absorption data with Merkulova's model [“Acoustic Properties of Some Solid Heterogeneous Media at Ultrasonic Frequencies,” Sov. Phys.—Acoust. 11, 55–59 (1965)] is given.
Active Electroacoustic Absorbers
Authors: Bobber R. J.
Published: October 2005

The behavior of an active electroacoustic transducer has been analyzed for optimum operation as an absorber of underwater sound—specifically as the characteristic impedance of an acoustic transmission line. It was found that the electronic generator that controls, but does not necessarily drive, the transducer functions primarily as a means for tuning out the mechanical reactance. A secondary function is to load the transducer electrically with either a positive or negative resistance, depending on the magnitude of the mechanical resistance. Most of the energy is absorbed in the mechanical resistance. The blocked electrical impedance of the transducer has a negligible role in the absorption process. Control of the transducer by the electronic generator is not critical. Conventional transducer design can be used.
Low-Noise Condenser Microphone
Authors: Erikson Kenneth
Published: October 2005

The limiting self-noise level of a conventional condenser microphone is determined by the Nyquist noise of the backplate air film resistance. This acoustic resistance is used to damp the microphone diaphragm for flat frequency response near the resonance frequency. This paper discusses condenser microphones constructed with backplates of very low acoustic resistance. Reductions in self-noise on the order of 40 dB can be achieved. Electronic compensation for flat frequency response can then be introduced at a point in the circuitry that does not add noise. With this noise source eliminated, the Nyquist noise of the acoustic radiation resistance and the internal mechanical resistance of the diaphragm become the limiting noise levels. Measurements of these noise levels are discussed.