bluuebunny/crossref_metadata_2025 huggingface dataset:
Tonotopic Organization of the Auditory Thalamus of the Squirrel Monkey
Authors: Gross N. B. , Lifschitz W. S. , Anderson D. J.
Published: October 2005

Single unit responses were recorded from the auditory thalamus of anesthetized squirrel monkeys. The microelectrode penetrations had an orientation perpendicular to the sagittal plane. The small cell division is tonotopically organized such that the cells in the most lateral aspect of this division have their ‘best frequencies” (BF) in the low-frequency range with a progressive shift in the BF toward the higher frequencies the further medially the sampling progressed, with 37 kHz being the highest BF recorded. Dorsal to and extending ventro-medially are large cells which are darkly stained. In addition, there is a bulbous extension more ventrally of large cells, less dense and perhaps less darkly stained. Cells in these subdivisions were not always responsive to tones. Within the border region of the small cell division and both the ventro-medial extension of the large cell division and the large cell division of bulbous extension, there was a high to low sequence within a comparatively short distance. Beyond this region, in both subdivisions, there were one or two additional reversals of BF.
Tonotopic Organization over Levels of the Auditory System for Cat and Rat
Authors: Clopton B. M. , Winfield J. A. , Flammino F. J. , Miller J. M.
Published: October 2005

Published information on single-unit tonotopic organization at the CN, SOC, NLL, IC, MGB, and auditory cortex in cat was examined for least-squares fit with various functions. Linear and log regressions of characteristic frequency on anatomical distance were generally more successful than other possibilities such as power functions, but certain conclusions held regardless of the function. Distance devoted to the frequency range decreases progressively from CN to MGB. Goodness of fit, an index of tonotopic organization, decreases progressively from CN to cortex. The second conclusion suggests that organization emanating from frequency analysis at the receptor is reflected at a given level after a cumulative diffusion at preceding levels. Possibilities for the nature of this diffusion process were considered and comparative implications were investigated using the rat. Tonotopic organization of single units at CN and IC was examined and compared to the cat data. [Supported in part by the National Institute of Neurological Diseases and Stroke.]
A Digital Signal-Processing Technique Applied to the Analysis of Cochlear Nerve Potentials
Authors: De Sauvage R. Charlet , Anderson D. J. , Pugh J. E.
Published: October 2005

A digital correlation method has been used to determine relative amplitude and latency relations among auditory-nerve averaged evoked responses (AER). The potentials used as examples were recorded in the proximity of the guinea pig cochlea in response to acoustic clicks ordered in intensity from 0 to 80 dB above threshold. Twenty to one hundred sample sequencies, each containing 240 values spaced 50 μsec apart were averaged. The response to the highest intensity click is taken as a master AER and each successive AER was measured with respect to it. The calculations consisted of determining the maximum magnitude and corresponding shift value of the circular cross-correlation function between the master AER and each series member. An economized search procedure was used to find these maxima. Savings were obtained by assuming that lower sound intensities result in longer latencies and that only points corresponding to shift values in the immediate neighborhood of the previously determined maximum need be computed. The usual method (“L” Electro-Cochleogramme, J. M. Aran and M. Portmann, Bordeaux, France) consists of estimating the peak-to-peak amplitude of N1 and its latency directly from the AER. Although the peak-to-peak method is simpler to implement, it requires a more favorable signal-to-noise ratio. For clinical applications, the benefits from the correlation technique are derived from a lower number of samples but more importantly from the possible use of a non-invasive recording technique versus the transtympanic approach of Aran.
Right-Ear Advantage in Choice Reaction Time to Monaurally Presented Vowels: A Pilot Study
Authors: Studdert-Kennedy Michael
Published: October 2005

In a pilot experiment with five subjects, monaural reaction times for the identification of three synthetic, steady-state vowels, /ɪ,ɛ,æ/, were measured as a function of their duration (80 msec vs 20 msec). On the long (80 msec) vowels, four of the five subjects were faster in identifying vowels presented to their right ears than those presented to their left. But the mean right-ear advantage of 22 msec was not significant. On the short (20 msec) vowels all subjects showed a right-ear advantage and the mean advantage of 48 msec was significant. The shift in the right-ear advantage, as a function of vowel duration, showed small between-subject variability and was highly significant.
Perceptual Difficulty and the Right-Ear Advantage for Vowels
Authors: Godfrey John J.
Published: October 2005

An experiment was designed to test the hypothesis that the right-ear advantage for speech in dichotic listening is correlated directly with perceptual difficulty, whether due to an inherent property of the stimulus (such as the “encodedness” of consonants) or to other loading factors in the perceptual situation. Brief vowel excerpts were presented dichotically, and perceptual difficulty allowed to vary along three dimensions: duration of stimuli, S/N ratio, and phonetic discriminability among vowels. Significant right-ear advantages were indeed found, although not entirely in accord with the original hypothesis. Results are discussed in terms of both the degree of perceptual difficulty and the speech-processing mode of perception.
Ear Advantage for Stops and Liquids in Initial and Final Position
Authors: Cutting James E.
Published: October 2005

Some parts of the sound pattern of speech appear to require more linguistic processing than others. In general, consonants require more processing than vowels. The magnitude of the right-ear advantage in dichotic listening tasks is one measure of the amount of linguistic processing necessary for certain classes of speech sounds. Consonants typically yield right-ear advantages while vowels typically yield no ear advantage. The present study observed the ear advantage for stop consonants and liquids, while varying the syllable position in which they occurred. In an ear-monitoring task subjects identified the stops in pairs like /bi/-/gæ/ and /ib/-/æg/, and the liquids in pairs like /li/-/ræ/ and /il/-/ær/. Stops yielded equal right-ear advantages in both initial and final position. Liquids showed a different pattern of results: initial liquids yielded a right-ear advantage, while final liquids yielded no ear advantage. These results suggest that initial liquids are perceptually more like consonants, while final liquids are perceptually more like vowels.
The Effect of Varying Labels on the Identification of Speech and Nonspeech Stimuli Presented Dichotically
Authors: Muraski A. A. , Sharf Donald J.
Published: October 2005

When stop bursts labeled as speech sounds were presented dichotically, subjects identified them correctly more often with the right ear than with the left. When labeled as noises of varying pitch, they were identified more often with the left ear than with the right. In the experiment to be presented two types of stimuli, stop bursts (/p,k,t/) and narrow-band noise bursts with frequencies centered around 250 Hz, 1000 Hz, and 4000 Hz were presented in both monotic (control) and dichotic (test) conditions. Forty subjects were divided into four groups. Two of the groups were given stop bursts only, the other two noise bursts only. Of each pair, one group was first instructed to identify the stimuli as speech sounds (/p/, /k/, or /t/), the other as noises of different pitch, low, middle, or high. The tests were then repeated with the instructions reversed. A significant right-ear advantage for stop bursts was found when the first instruction called for speech labeling and a non-significant left-ear advantage when the first instruction called for pitch labeling. No significant left-or right-ear asymmetry was found for noise bursts with either the pitch or the speech labeling condition, regardless or order of presentation.
Effects of Attenuation of One of Two Channels on Perception of Opposing Pairs of Nonsense Syllables When Monotically and Dichotically Presented
Authors: Brady-Wood Susan , Shankweiler Donald
Published: October 2005

A two-channel listening experiment was carried out in which subjects had to identify each member of pairs of nonsense syllables which coincided in time of onset and offset. The purpose of the experiment was to compare the effect of varying the intensity of the stimuli in one channel when stimuli pairs were presented dichotically (one to each ear) with the effect that occurred when both stimuli were directed monotically to a single ear. We could thus compare the effect of attenuation of one of the two competing speech signals when the competition involved peripheral masking (the monotic condition) with the effect obtained when the locus of masking was exclusively central (the dichotic condition). In the monotic case, the decrement in identification performance was nearly asymptotic with 10 dB of attenuation, whereas in the dichotic case the decrement in performance with attenuation was much less steep, not having reached asymptote at 25 dB of attenuation. These results agree with findings in visual masking studies with respect to the relatively greater importance of intensity difference among stimuli in peripheral masking than in central masking. [This research was supported in part by NSF Grant No. GJ-9.]
The Effect of Varying Syllable Microstructure on Voiceless Preponderance in Dichotic Listening
Authors: Berlin Charles I. , Hughes Larry F. , Thompson Carl L. , Cullen John K. , Hannah Joseph E.
Published: October 2005

Previous data [S. S. Lowe, J. K. Cullen, Jr., C. I. Berlin, C. L. Thompson, and M. E. Willett, J. Speech Hearing, Res. 13, 812–822 (1970); C. I. Berlin, M. E. Willett, C. L. Thompson, J. K. Cullen, Jr., and S.S. Lowe, J. Acoust. Soc. Amer. 47, 75–76 (1970)] show that when the onsets of the six English stops are aligned in dichotic CV pairs, voiceless CVs are more intelligible than voiced. This experiment reports the effect of maintaining onset alignments but changing voicing onset times (VOT) of the syllables. Thus, two types of voiceless CVs (+60 and +90 msec VOT) and two types of voiced CVs (−30 and 0 VOT) competed with each other in a dichotic paradigm. Changing VOT for the voiceless items had little effect on overall intelligibility. Using a 0-msec VOT voiced item, however, generated greater probability that the voiceless dichotic items would be perceived correctly. The relationship of this observation to the “lag effect” and suppression of one item by another will be discussed.
Regulations Concerning Power Plant Environmental Impact Statements and Noise Control
Authors: Bradley Wayne E.
Published: October 2005

A prolific amount of legislation concerning power plant noise control has emerged during recent months. The degree to which these regulations affect an individual station depends largely upon the type of plant, its location, and whether it is an existing or proposed installation. This new legislation may be divided into two different but closely related categories concerning (a) the preparation of environmental impact statements and (b) noise control to meet various federal, state, and local codes. Environmental impact statements are often requested for new installations by the AEC, Corps of Engineers, or state agencies, depending on the type and location of the station. While some agencies are vague in requesting noise information, others are more specific and require a considerable amount of information. The OSHA in-plant sound level criterion governing the allowable employee exposure is presently the only specific noise regulation applying to all existing and proposed plants. However, states, counties, and cities are rapidly promulgating specific property line criteria governing day and nighttime octave-band sound-pressure levels, pure tones, maximum short-term sound levels, and construction noise. Meeting these codes frequently involves substantial interior and exterior noise control.
OSHA Compliance Plans for Power Plant
Authors: Mull Harold R.
Published: October 2005

Widespread enforcement of the noise control provisions of the Occupational Health and Safety Act is just getting underway. Therefore, companies now being cited for excessive noise will have little precedent to guide them. Initial reaction is often one of dismay, with a desire to contest the action. Most companies, however, will decide to comply with the regulations. This means a compliance plan must be made and submitted to OSHA for approval. A typical plan could include control of individual noise sources, retirement of noisy machines, mandatory hearing protection, and changes in processes. The various steps in the plan must be scheduled with completion dates shown. The elements of a typical plan are discussed and options described.
Design of Forced and Induced Draft Fan Silencing Systems to Meet Community and Hearing Damage Noise Control Requirements
Authors: Schiff M. I.
Published: October 2005

The noise generated by forced and induced draft fans is a serious consideration in the selection of a site of new steam-generating power plants and in the choice of the proper fan equipment. Until the enactment of OSHA, the concern of the power plant designer was directed to the effect of fan noise on the community. In most cases noise control equipment was installed to local code requirements (where they existed) or to satisfy neighborhood complaints. With the passage of OSHA, a new dimension was added to power plant noise control. Community concern is no longer the sole criterion. It is now necessary to control the noise within the power plant to safeguard employees' hearing. This paper will indicate the procedures that an engineer should follow to ensure that forced draft and induced draft fan noise will meet OSHA requirements as well as those of the community. The acoustical considerations of silencer and fan-room noise control equipment will be analyzed and checked to determine d noise control has achieved appropriate design limits for power plant operators as well as the neighborhood community.
The Sea Surface as a Random Filter for Underwater Sound Waves
Authors: Fortuin L.
Published: October 2005

The random filter can be divided into two parts that are connected in parallel: a deterministic part (describing the coherent reflection) and a purely random part (characterizing the incoherent scattering). The former is determined by the mean value of any system function, e.g., the transfer function; the latter represents the fluctuations around that average value. Both filter sections can be described by surface integrals derived from the Helmholtz integral [L. Fortuin, J. Acoust. Soc. Amer. 52, 302–315 (1972)]. Numerical evaluation of these surface integrals reveals that in many practical cases they produce the same results as the Fraunhofer approximation. Using the Fraunhofer formula for the random filter part, its correlation properties in time, frequency, and space are analyzed.
Pressure Dependence of MgSO4 Acoustic Relaxation Frequency in the Ocean
Authors: Bezdek H. F.
Published: October 2005

Utilizing horizontal transmission paths located at various depths in the ocean, the absorption of sound waves has been measured at nominal frequencies of 30, 44, 60, 75, 90, and 144 kHz. Analysis of the data indicates that both the relaxation frequency, which is usually attributed to the presence of MgSO4 in the sea, and the chemical compressibility are functions of pressure. As pressure increases, the relaxation frequency shifts upward, from a value of 45±12 kHz at a depth of 200 m to a value of 70±15 kHz at a depth of 2800 m.
Dependence of the Low-Frequency (1 kHz) Relaxation in Seawater on Boron Concentration
Authors: Fisher F. H. , Levison Stuart A.
Published: October 2005

Earlier work reported at the 84th Meeting of the Acoustical Society of America [F. H. Fisher, E. Yeager, R. Bressel, and J. Miceli, J. Acoust. Soc. Amer. 53, 364(A) (1972)] indicated that the boric acid-borate system was responsible for the low-frequency sound absorption in seawater. By diluting seawater with 0.7M NaCl, the relaxation time, measured by the T-jump method, increased approximately inversely proportional to the boron concentration, indicating a bimolecular reaction. To decrease the relaxation time in order to put the relaxation in a more accessible region for acoustic experiments, boron was added to seawater. Measurements by the T-jump method showed no substantial change in the relaxation time for boron concentrations 2×, 5×, and 10× the seawater value of 0.0004M. This indicates that at least two steps are involved in the chemical reactions related to the 1-kHz relaxation. [This report is the result of research sponsored by the Office of Naval Research.]
Experiment Analysis of the Motion of a Vibrating Membrane by Optical Spatial Filtering
Authors: Clark J. A. , Mehta A. V.
Published: October 2005

An optical spatial filtering method of vibration analysis described previously [J. A. Clark, J. Acoust. Soc. Amer. 53, 338(A) (1972)] is employed to analyze the modes of vibration of an acoustically excited circular membrane over a broad range of frequencies. Data are obtained as whole field iso-slope contours displayed on the membrane image. Examples are shown of data recorded by time average, real time, and stroboscopic photographic methods. Several calibration procedures are described and compared. The analysis clearly reveals an extensive set of circular vibrational modes which can be identified with exact theoretical solutions. The Q of each mode is found to be easily determined. Effects of anisotropic tension and changes in the manner of acoustical excitation are also described. [This work supported by ARPA and monitored by ONR.]
On the Influence of Shear and Rotary Inertia on the Vibrations of Thin Circular Rings
Authors: Maddox N. R. , Rentzepis G. M.
Published: October 2005

A higher-order theory of free oscillations is derived here by adopting Novozhilov's thin shell theory, restricting the motion of the toroidal shell's cross section in its own plane to that of a rigid body, while permitting it to warp out of it, and by employing Hamilton's principle. The reduction from the shell theory to a ring theory is accomplished through a lengthy procedure which permits a systematic incorporation of the shear effects and the rotary inertia terms into the equations of motion. Assuming that the plane of the ring is a plane of symmetry the equations of motion reduce to two separate sets, one for the in-plane motion, the other for the out-of-plane motion. The influence of the shear and rotary inertia terms is subsequently examined. It is shown that their presence has no pronounced effect on the eigenfrequencies of the in-plane and out-of-plane vibrations for small radii ratios and low number of nodes. However, as the radii ratio increases or/and the number of nodes increases the influence of shear and rotary terms becomes serious. For the torsion predominant nodes their influence is profound for a larger spectrum of values of radii ratios and number of nodes.
Forced Response of a Discontinuously Constrained Damped Ring
Authors: DiTaranto R. A. , Lu Y. P. , Douglas B. E.
Published: October 2005

Experimental and theoretical results are presented and discussed for the radial driving-point mechanical impedance of a damped composite ring made of a thin-walled ring having a finite number of mass segments equally spaced and attached to its circumference by a viscoelastic material. The theoretical analysis considers the kinetic and potential energies of a thin-walled ring; the kinetic energies of tangential, rotational, and radial motions of each of the mass segments; and the energy of the viscoelastic material due to the relative motion of the ring and mass segments. The effects of the operational temperature and frequency ranges of concern on the viscoelastic material properties are taken into account in the analysis and calculations. Radial point impedance tests were conducted on two steel rings (4.06 and 5.125 in.) having 12 and 16 mass segments attached with an acrylic base viscoelastic material and a coal-tar base epoxy, respectively. Experimental data show good comparison with theoretical results over a wide frequency range of interest.
Surmounting the Inherent Errors in the Trifilar Pendulum Measurement of Moment of Inertia
Authors: Pal D. , Gaberson H. A.
Published: October 2005

The trifilar pendulum is a comparatively simple apparatus for the measurement of the moment of inertia, but a thorough analysis of the many potential errors in such measurements does not exist in the literature. It typically consists of a circular platform suspended by three parallel cables attached equidistantly around a circle near the periphery of the platform. One measures the period of torsional oscillation of the pendulum empty and with the object in question centrally placed on the platform, and from a simple formula obtains the moment of inertia of the object about the axis of rotation. The published theory assumes that the object to be measured is placed on the platform with its mass center coincident with the mass and geometric centers of the platform. A detailed analysis of the error introduced by mass center offset is presented. All of the various measurements and pendulum properties are examined to evaluate the maximum possible total error. The final equation clearly shows the effect of the ratios of platform to object mass and moment of inertia. It is shown that period measurement is the most sensitive of the required measurements. An error estimation formula is given.
Simulation of Multicorrelated Random Processes Using the FFT Algorithm
Authors: Wittig L. E. , Sinha A. K.
Published: October 2005

A technique for the digital simulation of multicorrelated Gaussian random processes is described. This technique is based upon generating discrete frequency functions which correspond to the Fourier transform of the random processes and then using the fast Fourier transform (FFT) algorithm to obtain the actual random processes. The main advantage of this method over other methods is computation time; it appears to be more than an order of magnitude faster than present methods of simulation. One of the main uses of multicorrelated simulated random processes is in solving nonlinear random vibration problems by numerical integration of the governing differential equations. [This research is supported in part by NASA.]
Middle-Ear Transmission Change as Measured by Aural Combination Tone Phase Behavior
Authors: Rabinowitz W. M. , Goldstein J. L.
Published: October 2005

The phase of the prominent 2f1 − f2 inner-ear aural combination tone is strongly dependent, by 6° to 12°/dB, upon the lower primary stimulus component amplitude. This phase sensitivity has been exploited to measure middle-ear transmission change during the application of static differential eardrum pressure (0 to ±400 mm H2O) and from activation of the acoustic reflex by intense contralateral noise. Increasing pressure differentials cause increasing transmission reductions with about 20-dB attenuation obtaining at 625 Hz for +300 mm H2O pressure (external ear minus middle ear). With the acoustic reflex, middle-ear attenuation is graded with contralateral eliciting level and reaches about 10 dB at 625 Hz for the maximal elicitor used. These data are in good agreement with published work, and form the basis for an expanded study of human middle-ear mechanisms.
Excitatory and Inhibitory Events in Hair Cells and Afferent Nerve Terminals Explored with Intracellular Microelectrodes
Authors: Flock Åke
Published: October 2005

Intracellular penetrations of hair cells and supporting cells, verified by electrophoretic dye marking, were obtained in the lateral-line canal organ of the burbot (Lota lota). Cells with a high membrane potential (range 10–65 mV) had a high resistance (range 8–110 MΩ). In response to a 70-Hz stimulus, hair cells generate a receptor potential of the fundamental frequency which can be contaminated, in damaged cells, by the external microphonic potential recognized as second harmonic distortion. In supporting cells nothing or a small second harmonic was seen. When efferent nerve fibers were fired, long-lasting hyperpolarizing potentials developed in hair cells but not in supporting cells. Simultaneously, there was a decrease of cell resistance and an augmentation of the receptor potential. Excitatory postsynaptic potentials (EPSPs) were recorded intracellularly from nerve terminals within the sensory epithelium, presumably from their non-myelinated portions. These are graded depolarizing pulses, with amplitudes of 0.5–2 mV and a duration of about 2 msec. Spontaneously, they occur at random; during stimulation they summate temporally and phase-lock to the stimulus. Efferent stimulation reduces the amplitude of the EPSPs and decreases the probability for firing of action potentials in the myelinated afferent nerve fibers.
The Tectorial Membrane: Position and Ion Content Studied with the Electron Probe
Authors: Flock Åke
Published: October 2005

When a beam of high-energy electrons excites atoms in a specimen surface, electrons and electromagnetic irradiation are emitted. Such electrons are used to create the scanning electron microscope image. The energy spectrum of x rays emitted by each element is characteristic of its atomic weight, which can be determined by an x-ray spectrometer. In this study non-fixed guinea pig temporal bones, rapidly extirpated and with bulla opened, were quenched in liquid propane at −192°C. The cochleae were fractured under liquid nitrogen, freeze dried, and covered with a thin layer of gold. This procedure brings to a minimum artifactual distortion of topography and ion redistribution. It was found that the lower surface of the tectorial membrane is roughly parallel to the reticular lamina from the Hensen cells to a point on the modiolus side of the inner hair cells. The scalae contain a fibrous matrix which captures ions during freeze-drying. X-ray spectroscopy shows emission from Cl and K in scala media, from these ions in the same relative proportions in the tectorial membrane and inner sulcus, but from Cl only in scala tympani. It is concluded that the tectorial membrane and subtectorial space belong to the endolymphatic compartment.
Direct Current Potentials due to Parametric Excitation of Cochlear Hair Cells
Authors: Boston J. R.
Published: October 2005

Davis's suggestion that the CM is produced by a periodic change in hair-cell resistance [Symp. Quant. Biol. 30, 181–189 (1965)] has been widely accepted. It has also been suggested by several investigators that the summating potentials observed in the cochlea are due to an asymmetry in the hair-cell transduction process. Theoretical considerations presented in this paper show that the parametric excitation implied by Davis's model is sufficient to produce a dc cochlear potential without assuming an asymmetry. Further, parametric excitation interacts with any asymmetries in the transduction process, modifying the effects of the asymmetries. The nature of the parametric interactions are demonstrated by considering the hair-cell transduction process to be a parametric process with a specific type of asymmetry. The asymmetry can be justified on a physiological basis, and the resulting dc potential has properties in common with the observed SP−, specifically, a linear growth with excitation until a saturation level is reached at high excitation.
Mechanical Response to Electric Stimulation of the Cochlea
Authors: Moxon E. C.
Published: October 2005

Single auditory-nerve fibers in anesthetized cats respond to sinusoidal electric stimuli delivered to the cochlea through electrodes contacting the round-window membrane and the periosteum of the middle-ear cavity. In addition to a response component attributable to direct electric excitation of nerve, a type of response is found in which analogous electric and acoustic stimulus waveforms appear to be transformed similarly into patterns of auditory-nerve activity. The response characteristics suggest that this response type is mediated by a linear cochlear electromechanical phenomenon. Measurements of round-window membrane motion confirm the existence of the postulated electromechanical transduction. In the range of measurement (100 Hz to 12 kHz), round-window volume velocity is proportional to stimulus current, the constant of proportionality being approximately 3×10−6 cm3/mA-sec. This electromechanical effect is essentially independent of normal mechanical-to-electrical cochlear transduction processes. The results indicate that a cochlear electromechanical phenomenon may be responsible for one type of perceptual response which has been described in reports of the effects of electric stimuli on the human cochlea. [Supported by NIH Grants GM01555 and NB01344.]
Electrophysiological Audiograms from the Peripheral Auditory System of the Bat Pteronotus parnellii
Authors: Pollak G. D. , Henson O. W.
Published: October 2005

Electrodes implanted adjacent to the perilymphatic duct were used to record cochlear microphonic (CM) and N1 (auditory nerve) potentials evoked by constant frequency tone bursts in five unanesthetized Pteronotus p. parnellii (Gray). The CM audiograms were very sharply tuned to a frequency between 60 and 63 kHz and were similar to those previously described by Pollak et al. [Science 176, 66–68 (1972)]. The N1 potentials had both ON and OFF components. The N1 OFF audiogram exhibited sensitivity peaks are 91 kHz, 70 kHz, and 60–63 kHz. The N1 OFF peak in the 60–63 kHz region corresponded in frequency to the peak in the CM audiogram. The sensitivity peaks at 70 and 91 kHz were not nearly as sharp as the peak in the 60-kHz region. No tuning was observed in the N1 OFF audiogram at frequencies below 60 kHz and the thresholds for these frequencies were high in each animal. The N1 ON audiogram was a mirror image of the N1 OFF audiogram; the ON thresholds were low for the frequencies at which the OFF were high and vice versa. The N1 ON response audiogram had one fairly sharp sensitivity peak at about 63 kHz and a sharp insensitive peak at 91 kHz. The ON thresholds for the frequency range 25–55 kHz were uniformly low. The frequencies of the fundamental and second and third harmonics of the emitted pulses and returning echoes closely correspond to the tuned peaks and the low ON thresholds (25–55 kHz) of the neural audiograms. Previous reports have stressed the importance of the 45–60 kHz second harmonic as a source of information but the neural audiograms strongly suggest that the 22–30 kHz fundamental and 67–90 kHz third harmonic are also important components of P. parnellii's biosonar signals. [Supported by PHS Grant NB7616-11.]
Effect of Ethacrynic Acid upon Energy Utilization in the Cochlea
Authors: Kusakari J. , Thalmann R.
Published: October 2005

The influence of ethacrynic acid (EA) upon the endolymphatic potential (EP) and the high-energy compounds ATP and P-creatine in the stria vascularis was studied at control conditions and following ischemia. While both EP and high-energy phosphates drop rapidly and at comparable rates due to ischemia and other interferences with energy production (cyanide or dinitrophenol), no major changes in high-energy phosphates occur when EP is severely depressed due to EA intoxication. Moreover, if EA-intoxicated ears are subjected to ischemia the levels of ATP and P-creatine are maintained much longer than in untreated controls, and the decline of EP is much slower with initial rates of change roughly proportional to the preischemic (predamaged) level of EP. These findings, obviously expressions of a reduced metabolic rate, indicate that the early effects of EA upon EP are not caused by an impairment of energy production or by changes in permeability, but rather are due to an interference with energy utilization, most likely by inhibition of the energy consuming processes mediated by the Na+K+-ATPase system.
Differences in Auditory Sensitivity Between Guinea Pig and Chinchilla
Authors: Drescher D. G. , Eldredge D. H.
Published: October 2005

Species differences in (a) acoustic impedance at the tympanic membrane and (b) the ratio of sound pressure at the tympanic membrane to sound pressure in the field (Pd/Pf) contribute significantly to species differences in (1) behavioral auditory thresholds and (2) sensitivity to noise-induced cochlear fatigue. Chinchillas exposed continuously for two or more days to an octave band of noise centered at 0.5 kHz at 105 dB SPL or centered at 4.0 kHz at 80 dB SPL show shifts in behavioral auditory thresholds of more than 50 dB at appropriate frequencies and corresponding loss of sensitivity for cochlear microphonic responses. Guinea pigs show only trivial loss of CM under the same exposure conditions. CM measurements indicate that in the chinchilla the transmission ratio, bulla closed/bulla open, is approximately 0 dB, but at low frequencies in the guinea pig transmission ratios of about −18 dB corresponding to impedance changes described by Zwislocki [J. Acoust. Soc. Amer. 35, 1034 (1963)] are confirmed. Also, in the guinea pig resonances for Pd/Pf occur at 7.5 to 10 kHz in contrast to the resonances at 2.5 to 5 kHz in the chinchilla [G. von Bismarck, M. S. Thesis, MIT, Cambridge, Mass. (1967)].
Ultrasonically Induced Cavitation in Biological Tissues
Authors: Senapati N. , Lele P. P.
Published: October 2005

Knowledge of the mechanism of tissue damage by ultrasound of low megahertz range is essential for prediction of safe dosage levels for diagnostic applications as well as for the prediction of the reproducibility of its therapeutic effects. This communication will deal with the cavitational aspects of tissue damage. Studies on ultrasonic irradiation of prepared non-biological liquids showed characteristic acoustic emissions of strong half-harmonic signals from the media, the power content of which was found to be fairly stable. The half-harmonic power has been defined as the “cavitation intensity,” which was found to increase exponentially with the irradiation intensity. Similar studies on blood plasma and frog liver confirmed the presence of cavitation as well as the functional relationship between the cavitation intensity and the irradiation intensity. The acoustic emission from the target during the ultrasonic irradiation of the cat brain was also characteristic of cavitation. For focused beams of ultrasound, as are normally used to cause focal lesions at the target, the cavitation intensity distribution at the target was computed from the acoustic intensity distribution. In order to predict the ultrasonic damage to structurally homogenous tissues, the computed cavitation intensity was correlated with the stress and energy intensity in the media. Based on the nature of the cavitation spectrum, statistical models were developed to predict tissue damage, due to single ultrasonic bursts, as a function of irradiation parameters, viz., the total acoustic power, pulse duration, and irradiation frequency. The predicted damage has been found to correlate well with the published experimental data.
Ultrasonic Attenuation in Tissues
Authors: Allegra J. R. , O'Day P. M.
Published: October 2005

The possibility that a thermal conduction mechanism might explain the high attenuation of ultrasound in biological systems is reported. This thermal conduction mechanism arises due to inhomogeneities in the biological materials. It is known that this thermal conduction mechanism is quite significant for small inhomogeneities (0.1 to 1 μ) at frequencies between 1 and 10 MHz .This knowledge is applied to biological materials with the understanding that these materials contain inhomogeneities of this same approximate size. It is found that this mechanism could explain the observed linear frequency dependence of the ultrasonic attenuation in many biological materials, and also that the observed high attenuation can be accounted for in this theory. It is also shown that the thermal conduction attenuation for proteins the size of hemoglobin is small compared to the experimental data.
Ultrasonic Reduction of Mitotic Activity in Regenerating Rat Liver
Authors: Kremkau F. W. , Witcofski R. L. , Meschan I.
Published: October 2005

In the adult rat liver there is ordinarily little cell division, but in response to an urgent demand for cells (as occurs after partial liver removal) large numbers of cells divide. The purpose of this study was to measure levels of mitotic activity (stimulated by partial hepatectomy) after ultrasonic treatment of the intact liver. Anesthetized male Charles River rats were treated with ultrasound and their mitotic indices compared with control animals. A continuous 2-MHz 100-mW/cm2 unfocused sound beam was oriented to impinge on the liver. The transducer was placed on the abdomen for a treatment time of five minutes. Temperature rises were less than 5°C at the transducer-abdomen junction and less than 1°C in the liver. Within two hours of treatment about 70% of the liver was surgically removed. Twenty-eight to 30 hours after partial hepatectomy (the time of peak mitotic activity in control animals) the mitotic index of the regenerating liver tissue was observed. Treated animals showed a reduction in mitotic index to about one-half that for controls. Statistical analysis showed the results to be significant at the 1% level. [This work was supported in part by grants from R. J. Reynolds Industries, Inc., and the USPHS, Food and Drug Administration, Grant RL-00129.]
Ultrasonic Velocity and Attenuation in Ammonium Dihydrogen Phosphate
Authors: Hanse J. G. , Leisure R. G.
Published: October 2005

The velocity and attenuation of ultrasonic shear waves have been investigated as a function of temperature in single-crystal ammonium dihydrogen phosphate (ADP). Particular emphasis was placed in the region near the antiferroelectric critical temperature. As the antiferroelectric transition is approached from high temperature, the dielectric polarization relaxes from the paraelectric to the antiferroelectric configuration. This relaxation process causes the shear velocity and attenuation to shift anomalously. This change in velocity can be described in terms of an elastic Curie-Weiss law with a negative absolute critical point. For the first time the ultrasonic attenuation measured near an antiferroelectric transition will be reported. The anomalous attenuation shift is used to calculate the polarization relaxation time associated with the transition and the relaxation time will be compared to existing microwave and Raman spectrum experiments.
Experimental Verification of the Parametric Array in Air
Authors: Bennett M. B. , Blackstock D. T.
Published: October 2005

An experimental investigation of the parametric array in air was conducted using a squirter transducer for the sound source. Separate elements of the transducer, excited at frequencies of 18.6 and 23.6 kHz, produced 16.2° and 16.6° primary beams, respectively. Since the source levels were not strong (typically 95–105 dB re 0.0002 μbar), the 5-kHz difference frequency signal generated by the parametric array was relatively weak. Preliminary measurements indicated the presence of spurious difference frequency signals as a result of intermodulation distortion in the receiving system. After the spurious signals were suppressed, by judicious choice of electronic components and by the addition of an acoustic filter in front of the microphone, the classic parametric array properties were observed. The 5-kHz beam was narrow (≃15°) and had no sidelobes; the beam narrowed slightly with increasing range. The propagation curve first increased, reached a broad maximum, and then gradually decreased. Because of space limitations, all measurements were taken in the nearfield of the parametric array. Beam patterns and propagation curves were also measured for the sum frequency and second harmonic signals. Comparison of the measured results with theory conclusively demonstrated the existence of the parametric array in air. [This work was sponsored by AFOSR and by ONR.]
Laser-Excited Pencil Beam Array
Authors: Larson Richard S. , Westervelt Peter J.
Published: October 2005

An intensity modulated laser beam is incident on a conical reflector which produces a spreading fan of light. The fan acts like an acoustic directional array, producing an acoustic beam along the incident direction of the laser beam. The radiated acoustic intensity in the farfield is given by I = 12ρ0c0(aωβP04πrcp)2 1a2+k2 sin2θ, where P0 is the average power of the laser, a is the intensity attenuation coefficient for the laser beam, θ is the angle measured from the laser beam direction, k = ω/c0, ω is the modulation frequency, c0 is the speed of light, cp is the specific heat per unit mass, β is the logarithmic coefficient of thermal expansion, and ρ0 is the density. Maximum radiation occurs at θ = 0. [This work was supported by the U. S. Office of Naval Research.]
Experiments on a Laser-Excited Array
Authors: Muir T. G.
Published: October 2005

The generation of highly directive sound through thermodynamic expansion of media illuminated by modulated laser light has recently been proposed by Westervelt and Larson [J. Acoust. Soc. Amer. 53, 384(A) (1973), and paper Q12, 85th Meeting Acoust. Soc. Amer.]. Measurements on the field of a thermoacoustic array so created are reported in the present paper. A pulsed ruby laser operating in the conventional mode was fired into an absorptive copper sulfate solution. The noiselike light burst was found to generate a sound burst perpendicular to the optical path with a directivity as predicted by the Westervelt-Larson theory. Data on the conversion efficiency and on other critical parameters of the experiment are discussed and interpreted with respect to theory. [This work was supported by the U. S. Navy Office of Naval Research.]
Wide-Band Response of the Parametric Acoustic Array
Authors: Foote K. G.
Published: October 2005

Westervelt's theory of the parametric acoustic array [J. Acoust. Soc. Amer. 35, 535–537 (1963)] is generalized to continuum sources of arbitrary spectral composition. A general expression for the angular distribution of difference frequency radiation is derived, in the random phase approximation, and evaluated for the case of a delimited band of white noise in a medium of constant attenuation.
Auditory and Phonetic Levels of Processing as Revealed by Reaction Time
Authors: Tash Jeffrey , Pisoni D. B.
Published: October 2005

When listening in the speech mode, a subject can identify the phonetic class of a sound but cannot discriminate between acoustically different sounds selected from the same phonetic category. Auditory information about the physical characteristics of these stimuli appears to be unavailable for use in discrimination as a consequence of phonetic categorization. Same-different reaction times (RT) were obtained to provide evidence for distinct auditory and phonetic levels of processing. Pairs of synthetic speech stimuli varying in voice onset time between /ba/ and /pa/ were presented to listeners who were required to respond “same” if both stimuli were the same phonetic segments (i.e., /ba/-/ba/ or /pa/-/pa/ or “different” if both stimuli were different phonetic segments (i.e., /ba/-/pa/ or /pa/-/ba/). RT for “same” responses was faster to pairs of acoustically identical stimuli (A-A) than pairs of acoustically different stimuli (A-B) belonging to the same phonetic category. RT for “different” responses was slower for a two-step difference than for a four-step or six-step difference across the boundary. These results indicate that low-level acoustic information may be available to listeners, but this is dependent upon level of processing required by the particular information processing task employed.
Perception of Some English Consonants Embedded in a Sentence
Authors: McGregor Lilian , Singh Sadanand
Published: October 2005

The purpose of this study was to investigate listeners' utilization of distinctive features in judging phonemic similarity in connected speech in varying noise and quiet conditions. Sixteen initial consonants were presented in monosyllables embedded within a simple declarative sentence in a position of relative unstress. Five listeners judged 1680 triads in random order in 6 dB, 12 dB, and no-noise conditions each. IND-SCAL analysis yielded a five-dimensional solution in the quiet condition. The features stop/fricative, sibilance, voicing, back/front, and velarity were retrieved on these dimensions. These features accounted for 28%, 16%, 9%, 9%, and 8% of the variance, respectively. A five-dimensional solution in the condition of 12 dB S/N ratio was interpreted as stop/fricative (30% of the variance), sibilance (25%), voicing (11%), and velarity (6% of the variance). The 6 dB S/N ratio condition was analyzed in a four-dimensional space. Interpretations were sibilance (28% of the variance), stop/fricative (20%), voicing (11%), and velarity (8% of the variance). When masking interfered the weighting of features changed; sibilance and voicing becoming more prominent in noise while front/back place disappeared. Individuals weighted features differently.
More on the Effects of Noise on the Apprehensibility of Consonant Attributes
Authors: Voiers W. D.
Published: October 2005

Miller and Nicely's classic work on the confusability of consonant phonemes yielded data only for a limited set of phonemes in a single vowel context and permitted no examination of the speaker's effect on phonemic confusions. The Diagnostic Rhyme Test (Form IV), as recorded by six male speakers, was administered to a listening crew under 11 conditions of speech-to-noise ratio. Results were analyzed to show the general effects of noise on the apprehensibility of six consonant attributes, the effects of vowel context on the apprehensibility of consonant attributes (transitive dependencies), and the effects on the apprehensibility of each attribute of the states of other attributes of the same phoneme (ipsative dependencies). The results were further analyzed to permit examination of the degree and nature of interspeaker differences in consonant intelligibility.
Intelligibility and “Tonality” of 200 Monosyllable Words (CID W-22) for 10 Half-Octave Bandpass Filtering Conditions
Authors: Ryals Brenda M. , Asp Carl W.
Published: October 2005

The 200 words were bandpass filtered separately through 10 adjacent half-octave conditions ranging from 210–297 Hz to 4709–6660 Hz. A separate group of eight normal-hearing adults judged each condition at a most-comfortable-loudness level. As expected, significantly higher intelligibility scores were obtained for the conditions 1177–1665 Hz and 1682–2378 Hz. Eighty-five (42%) of the 200 words achieved a score of 50% or greater for at least one of the conditions. These 85 words were assigned “tonality” (frequency) regions of low, low-middle, middle, middle-high, or high. The percent of words for each region was 2%, 11%, 69%, 17%, and 1%, respectively. The phonetic content of the words for each tonality will be discussed. The total intelligibility of each of the 200 words was computed across the 10 conditions. Fifty-one words (26%) had a total intelligibility score greater than 10%, 127 words (63%) had a score of between 1% and 9%, and 22 words (11%) had a score of 0%.