bluuebunny/crossref_metadata_2025 huggingface dataset:
Lateral Pharyngeal-Wall Movement during Esophageal Voice Production
Authors: Ewanowski Stanley J. , Hixon Thomas J. , Kelsey Charles A. , Minifie Fred D.
Published: September 2005

Time-motion modification of ultrasonic echo ranging, as described in preceding abstracts, was used to monitor pharyngeal-wall movement during prephonatory and phonatory stages of esophageal voice production. The data from several subjects, one of whom was rated as having excellent esophageal speech, showed a marked pharyngeal-wall displacement during the injection or prephonatory stage. Pharyngeal-wall movements during the production of VCVCV trisyllables and during connected speech were comparable to those of normal speakers. Outward movements were dominant during consonant production, while inward movements predominated during the production of vowels. Differences were noted between the production of high and low vowels. [This research was supported by the National Institutes of Health.]
Function of Laryngeal Muscles in Regulating Fundamental Frequency and Intensity of Phonation
Authors: Hirano Minoru , Vennard William , Ohala John
Published: September 2005

Electromyographic recordings of the activity of selected intrinsic laryngeal muscles of a professional singer and several untrained subjects were made during both singing and speech. The mechanism regulating fundamental frequency and intensity differed for different registers and fundamental frequencies. For low-pitched phonation in chest register, laryngeal muscles contributed pronouncedly to changes in fundamental frequency and intensity; whereas for high-pitched phonation in falsetto register, their contribution was less. Therefore, one can presume that for high falsetto the air-flow rate was the dominant factor regulating fundamental frequency and intensity. There was no essential difference of the muscular activity patterns between speech and singing in chest register as far as regulation of fundamental frequency and intensity of voice is concerned. [This research was partially supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare, and the Office of Naval Research.]
Experimental Investigations of the Muscular Control of the Tongue in Speech
Authors: Smith Timothy S. , Hirano Minoru
Published: September 2005

Using thin-wire bipolar electrodes, electromyographic recordings have been obtained from selected extrinsic muscles of the tongue and suprahyoid muscles. Five male subjects were used in this study, all of whom were speakers of general American English. In each case, the text consisted of 36 CVC nonsense syllables, in a suitable frame. In addition, an x-ray film was made of one subject pronouncing the basic text. Specific patterns of muscular activity have been isolated for the basic consonant and vowel gestures, but these patterns show systematic variation dependent upon phonetic context. It is of interest that the electromyographic patterns were relatively similar from subject to subject. The paper will discuss the relationship of the data to models of speech production. [This research was supported by the National Institutes of Health and the National Science Foundation.]
Coherence of Acoustic Signals Reradiated from the Time-Varying Surface of the Ocean
Authors: Parkins B. E.
Published: September 2005

The space and time variation of a monochromatic acoustic plane wave reradiated by the moving, rough surface of the ocean is described using coherence theory. The complex degree of coherence of the pressure field is calculated approximately for the extreme cases of slightly rough and very rough surfaces. For both of these cases, the results are specialized to the situation of a wind-generated sea described by the Neumann-Pierson directional wave spectrum, and the dependencies of the coherence upon surface roughness and the angles of incidence and observation are shown. For the case of a slightly rough surface, the reradiation is principally a reflection, and the coherence in the direction of specular reflection is the same as that for a smooth surface. Away from this direction, there is scattering; and the coherence depends upon the surface roughness. For very rough surfaces, there is diffuse scattering in all directions with no reflection; and the coherence depends upon the surface roughness for all angles of observation.
Results for a Surface-Loss-Measurement Program
Authors: Beam John P. , Nielsen Richard J.
Published: September 2005

A study of surface loss was conducted with a projector and two receivers mounted in deep water south of Bermuda. Using a pulse repetition rate of 8.3 sec, 84 sample records have been collected, each of which contains approximately 900 750- or 1500-Hz 30-msec pulses. Wind speeds during the course of the experiment ranged from 2.5 to 40 kt. Plotted against wind speed, the results of the experiment show that the mean loss for both frequencies increases quickly for winds above 20 knots. When mean surface loss is plotted against the frequency—wave-height, product the loss increases by 4.5 to 5 dB as the frequency—wave-height product increases from 3 to 42.
Reverberation from an Arbitrary Transient Source
Authors: Urick R. J.
Published: September 2005

For simple distributions of scatterers in the sea and with the customary assumptions needed for tractability, a simple expression is found for the reverberation level following emission of a source pulse whose envelope is an arbitrary function of time. The result is equivalent to convolving the source intensity function with the impulse response of medium plus scatterers. The impulse response is proportional to the product of a scattering coefficient and the inverse cube of the time for surface/bottom reverberation, and the inverse square of the time for volume reverberation. The result is found to reduce to the well-known expressions for the reverberation level for the two types of source waveforms commonly used in sonar: the flat-topped ping of definite duration and the short transient, specified only by its energy flux density at unit distance.
Resonant Acoustic Scattering from Air-Bladder Fishes
Authors: Batzler W. E. , Regan M. C. , Pickwell G. V.
Published: September 2005

Mesopelagic fishes inhabiting horizontally stratified layers are believed to be the principal source of strong back-scattering from these layers. The target strength of an individual fish is low and difficult to measure, even at its resonant frequency. A novel procedure that gives the scattering response, or target strength and resonance “Q,” as a function of frequency also yields a theoretical volume of air, which is then compared with the volume of the bladder. Measurements were made at NUWC's Transdec calibration pool. Small rubber balloons, live goldfish, anchovies, and Fundulus were used as acoustic targets. Acoustic frequencies used were in the range 0.4 to 4.0 kHz. All fish were small as compared with the acoustic wavelength. The balloon targets exhibited a fairly sharp resonant response with Q's as high as 15, corresponding to target strength enhancements of about 30 dB. The resonance curves for the scattering from fish targets were broader, and Q's in the range 3–5 were observed. With the bladders completely deflated, the fish produced no measurable response. Tests in a sound-transparent pressure chamber clearly demonstrate the upward shift in resonant frequency expected with increase in water depth.
Attenuation and Bottom-Reverberation Measurements in the Brazos River
Authors: Muir T. G. , Adair R. S. , Pruitt J. G.
Published: September 2005

The use of high-frequency acoustic techniques for detection and study of submerged objects and geological features in rivers can be limited by both attenuation and reverberation. These parameters were measured in a pilot study of the lower reaches of the Brazos River near Houston, Tex. The attenuation was due to the suspended particulate matter carried by this muddy river. At a frequency of 200 kHz and for a particulate concentration of 0.025% by weight, the attenuation was found to be 1.5 dB/100 yd. Reverberation from the bottom sediment was measured at a frequency of 85 kHz as a function of transducer grazing angle. The reverberation data are interpreted as a scattering strength per unit area of bottom insonification and fall in the range of scattering strengths reported by others for fine mud. [This work was supported by the Office of Naval Research.]
Amplitude Distributions of Monostatic Bottom-Scattered Signals
Authors: Hurdle Burton G. , Flowers Kenneth D. , Thompson Kingsley P.
Published: September 2005

Using a directional transducer, amplitude distributions of monostatic bottom-scattered signals were obtained for grazing angles from 90 to 30°. The area of operation was a region with nearly constant water depth, type of bottom, and roughness characteristics. The transducer was operated at 19.5 kHz and has a beam width of 8° to the half-power points. A number of long pulses were recorded with the source-receiver maintained at a constant depth and depression angle. The distributions for low angles tend toward Rayleigh. For grazing angles between 70° and 90°, the distributions deviate markedly from those of Rayleigh. The distributions in this region show a transition from near-Rayleigh at 70° to multiple-peaked distributions at 90°.
Laser Interferometer for the Measurement of Submicroscopic Displacement Amplitudes and Their Phases in Small Biological Structures
Authors: Khanna Shyam M. , Tonndorf Juergen , Walcott W. W.
Published: September 2005

An interferometer is described. It is designed for measurements of submicroscopic displacement amplitudes of small biological structures in living animals. Its output is frequency independent. The instrument may be used for measuring: (1) absolute displacement amplitudes as low as 3 × 10−10 cm between 20 and 20 000 Hz; (2) phase angles of the displacements with respect to that of the applied sound signals; and (3) transient responses of the vibrating structures. Theory of operation is discussed. Fabrication of microscopic mirrors and construction details of the interferometer are given. Experiments performed with the aid of an earphone as a vibrating object are included to show the characteristics of the interferometer. Calibration is precise (within 1 dB), and repeatability is excellent, both with respect to amplitude (within 1 dB) and phase within 5°. Experiments on living animals and cadavers, giving amplitude and phase data will be included in a separate paper. [This work was supported by grants from the National Institutes of Health.]
Submicroscopic Displacement Amplitudes of the Tympanic Membrane (Cat) Measured by a Laser Interferometer
Authors: Tonndorf Juergen , Khanna Shyam M.
Published: September 2005

A laser interferometer, designed and constructed in this laboratory, was evaluated with respect to its applicability to measurements of amplitudes and phases in the ear. In measurements on the tympanic membrane, the prevailing S/N ratio made it convenient routinely to measure amplitudes of 1 × 10−7 cm in living animals. At low frequencies, this corresponds to SPL's of approximately 60 dB. In fresh cadavers, however, while there was no immediate change in the magnitude of the responses, readings were extended to 1 × 10−9 cm owing to the absence of pulse and breathing. In all experiments, repeatability was excellent, and between-animal variations were low. The resulting characteristics obtained in living animals, with the tympanic bulla closed, was generally similar to those obtained earlier, with some noted exceptions. The amplitude curve failed to show the slight hump around 1 kHz found before. The phase curve was much more complex than earlier ones and cannot be approximated by the assumption of simple network models. [This work was supported by grants from the National Institutes of Health.]
Noise-Induced Hearing Losses in Cats: Effects of Bandwidth, Intensity, and Exposure Duration
Authors: Funasaka Sotaro , Elliott Donald N.
Published: September 2005

The cat's auditory threshold was determined with behavioral methods before and at intervals after exposure to intense thermal noise. Using two bands of noise with different upper cutoffs (500–504 and 500–508 kHz) and two intensity levels, exposure duration was gradually increased (three exposures at each D) until PTS occurred for each cat. The shapes of the postexposure audiograms were determined, and recovery curves were traced. The shapes of the postexposure audiograms were found to differ significantly as a function of the upper cutoff limits, the intensity levels, and the different exposure durations. For example, the frequency showing the greatest loss was not invariable across all conditions. In addition, there were significant individual differences in both the amount of TTS and the shape of the postexposure audiogram. The relationship between individual susceptibility to TTS and PTS was also determined and will be reported.
Hair-Cell Damage Produced by Toy “Cap Guns.”
Authors: Poché Lynn B. , Stockwell Charles W. , Ades Harlow W.
Published: September 2005

Fourteen young guinea pigs were individually exposed to 500 rounds of paper “caps” fired in a toy gun at a distance of 30 cm. The gun was fired at intervals of 1–5 sec. After 7 wk survival, the cochleas were removed and each complete organ of Corti examined using Engström's surface-preparation technique. Cochleograms (tabular forms showing position and condition of each cell) were prepared for each row of hair cells. Curves were plotted showing number of damaged cells as a function of distance from the round window. In approximately 80% of the cases, total destruction of hair cells occurred in a narrow band midway along the organ of Corti. Averaged curves of damage for the group are presented and compared with similar curves for another group that was exposed to high-intensity pure tones. [The research was supported by NASA contract.]
Thoughts on Language and Speaking
Authors: Halle Morris
Published: September 2005

A speaker's and hearer's knowledge of the language in which an utterance is produced plays a fundamental rôle in the understanding of the utterance. An attempt will be made to assess somewhat more precisely what knowledge of the language may contribute to understanding. A number of illustrative examples will be analyzed, and an attempt will be made to draw some inferences concerning the significance of these facts for further work on the automatic processing of speech.
New Lord Manufacturing Company Acoustical Facility
Authors: Holmer Curtis I.
Published: September 2005

A facility for measurement of transmission loss and sound-power radiation has recently been completed at Lord Manufacturing Company. The facility includes a source room of irregular shape (∼2100 ft3 volume), and a rectangular main reverberant room of ∼11 000 ft3 volume, both of 12-in. concrete-filled, concrete block construction. A unique feature is a modular steel panel filler wall for providing flexibility in varying TL sample size from 6×8-ft samples to 3×3-ft samples. Data are shown that indicate the facility is capable of reverberant-field TL testing with 110-oct resolution from 125 to about 10 000 Hz with samples up to about 16 lb/ft2 mass law. Beranek's criterion of 20 modes/band is satisfied in the main room to 63 Hz for 1-oct analysis, 80 Hz for 13-oct analysis, and 125 Hz for 110-oct analysis.
Decibel Averaging in Reverberant Power Measurements
Authors: Lubman David , Bowers Harry D.
Published: September 2005

The measurement of sound power in a reverberant room makes use of the level corresponding to room-averaged sound intensity, 10 log 〈I〉. But when measurements are in decibels—as is usually the case—it is computationally simpler to employ the room-averaged level 〈10 log I〉. This substitution leads to a bias in the direction of underestimating the true power. In many practical situations, the bias can be estimated theoretically and added as a correction term to the simple average level. For pure-tone excitation, the bias term is largest, amounting to 2.5 dB. For noise excitation, the bias decreases with the product of noise bandwidth B and reverberation time T. When BT>30, bias is less than 0.5 dB. When BT>130, bias is less than 0.1 dB; and decibel averages may be substituted for intensity averages with impunity.
Sound Transmission through Sandwich Panels
Authors: Holmer Curtis I.
Published: September 2005

An expression for the transmission coefficient of an infinite, symmetric sandwich panel is obtained by modification of Feshbach's expression [L. L. Beranek, Noise Reduction (McGraw-Hill Book Co., New York, 1960), p. 298, Eq. 13.28] for infinite homogeneous panels. Kerwin's theory of bending stiffness of a three-ply sandwich is used to obtain a ldquo;critical frequency.” The effect of finite shear stiffness in the sandwich core is to introduce a frequency dependence in the bending stiffness, which in turn implies a critical frequency, which is a function of driving trace wavelength. The expression derived may be numerically integrated to determine transmission loss in a diffuse sound field. Sample computations are compared with experimental results from several different panels. The predicted results compare very favorably with TL tests on panels with nearly free-free edges.
Influence of Diffusivity on the Transmission Loss of a Single-Leaf Wall
Authors: de Bruijn A.
Published: September 2005

Sound transmission loss tests on single-leaf walls have shown deviations from theoretically predicted values calculated for a random-incidence sound field acting on an infinitely large wall. Better agreement was obtained with the introduction of an upper bound for the integration with respect to the angle of incidence in order to obtain an average value for the transmission loss. Nevertheless, minor deviations persist, especially in the vicinity of the coincidence frequencies. In the present paper, the influence of diffusivity has been investigated by means of a random vibration method. The representation of the exciting pressure is given by the cross-correlation function in time and space. For a true random-incidence field, the function is given by φρr(r,ω) = sin(kr)/kr, where k is the wavenumber and r the distance between the points under consideration. This has been generalized to fit the wide range of correlation relations met in practice. Computations show that relatively large deviations from the random-incidence condition effect an upward shift of the transmission loss curve, but make only minor changes in its shape.
Effect of Shape of Transmission-Loss Curve on Subjective Reaction to Transmitted Noise
Authors: Clark Duncan M.
Published: September 2005

The use of single-number ratings is quite common in describing the acoustic performance of various building elements, e.g., the sound-transmission class of a wall or the impact-noise rating of a floor. The determination of single-number ratings involves certain assumptions regarding the relative importance of various frequency bands. In the sound transmission class (STC) rating system, for instance, a TL curve of irregular shape must be compared to a standard reference curve. The contribution of various frequency bands depends on the shape of the reference curve and on the method of comparison. An experiment has been carried out to determine subjectively the effect of various irregularities in TL curves as compared to a standard curve such as the STC contour. Results so far show that for frequencies in the range 500, 1000, and 2000 Hz, a dip 1 oct wide would effectively reduce the STC rating by 5 as compared to a dip 13 oct wide of the same depth.
Room-Acoustics Measurements, Using a Calibrated Steady-State Sound Source
Authors: Watters B. G. , Kirkegaard R. L. , Johnson F. R.
Published: September 2005

Auditoria are often assumed to be diffuse reverberant rooms to which the statistical theory of room acoustics may be applied. We believe that this assumption should be questioned in at least two commonly occurring situations. One is when the sound source is located in a “coupling” device such as a concert shell. The second is when the resulting sound pressure is to be evaluated at positions near the room's boundaries such as at a typical seated listener's head position. This second effect as it pertains to individual sound paths has been discussed earlier [T. J. Schultz and B. G. Watters, “Propagation of Sound across Audience Seating,” J. Acoust. Soc. Am. 36, 885–896 (1964)]. We have measured the steady-state SPL's in a number of auditoria, using a calibrated ILG sound source located on the stage. These values will be compared to the SPL's calculated from the source power level and the halls' volumes and reverberation times.
Radiation Characteristics of a Circular Transducer Surrounded by a Concentric, Structure-Reinforced Circular Shell
Authors: Hamilton K. B. , Douglass R. E.
Published: September 2005

A two-dimensional mathematical model consisting of a cylindrical radiator within a concentric elastic cylindrical shell with supporting structure has been treated. The structure was idealized as masslike stringers running in the same direction as the generatrix of the shell. A velocity distribution was specified on the radiator in order to produce a directive beam. Farfield beam patterns and velocity distributions on the shell were computed with and without structure to assess the effects of the structure. The numerical results, for the cases considered to date, exhibited large local velocities on the shell due to standing wave buildup in the presence of the structure. However, the farfield beam patterns were not altered as much by the addition of the structure as was the shell velocity.
Study of the Beam Patterns of a Cylindrical Transducer Array Located within an Elliptic Shell
Authors: Douglass Richard E.
Published: September 2005

A two-dimensional mathematical model consisting of a cylindrical radiator within an elliptic shell has been investigated. In this study, a velocity distribution was specified on the cylinder to simulate staves of a cylindrical transducer array. A portion of the staves were phased to a plane in order to transmit a directive beam. Farfield beam patterns were computed as the active array was steered by rotation within the elliptic shell. It was found that the peak intensity and side-lobe levels of the beam patterns varied with beam steering. The lobe structure was not symmetric about the main lobe for off-axis steering angles, and a region of relatively high side lobes appeared on one side of the main lobe. However, the main lobe was always in the beam-steering direction, and the beamwidth was not altered.
Transient Effects in Transducer Arrays
Authors: Sherman C. H. , Porter D. T.
Published: September 2005

The familiar transient behavior of electromechanical transducers vibrating in vacuum is modified by acoustic effects when these transducers vibrate in a medium such as water. These effects are of particular interest in the large transducer arrays used in sonar, where the acoustic interactions between transducers causes different transient behavior at different locations in the array. A finite-difference iteration solution of the differential equations that describe the interacting transducers has been carried out in order to investigate some of these effects. The acoustic interactions are included in an approximate way that becomes more exact as the transducers are made smaller. The velocity of each transducer is computed as a function of time from the instant of sudden application of the driving voltages until steady state is reached. The convergence of the method has been checked by comparison with independent calculations of the steady-state velocities. Results will be given and discussed for different transducer and array parameters including cases of beam steering.
Acoustic Radiation from a Random Line Source
Authors: Gardner S. B. , Lindemann O.
Published: September 2005

A general result is derived for the cross-spectral density of the velocity potential produced by stationary and homogeneous random sources distributed along an infinite line. The general expression is evaluated for a line of uncorrelated point sources. For separations parallel to the source axis, the normalized cross-spectral density of the velocity potential is given by a single Bessel function. For separations in the radial direction, the normalized cross-spectral density is complex with a real part given by a Bessel function, and an imaginary part given by a Struve function. These results may be useful in the development of a mathematical model for the sound field produced by a stream of bubbles. [Work supported by the Office of Naval Research.]
Tonotopic Arrangement of Narrowly Tuned Units in Primary Auditory Cortex
Authors: Abeles M. , Daly R. L. , Goldstein M. H. , McIntosh J. S.
Published: September 2005

Investigation of tuning characteristics of single units in AI of immobilized, unanesthetized cats revealed that about one-half of the units have narrow response ranges. Each electrode track was classified according to the characteristic frequencies (CF's) of its narrowly tuned units. The groups were: Tracks with unit CF's below 10 kHz, 10–20 kHz, 20–30 kHz, 30–40 kHz, and above 4:0 kHz. Track positions for each group were plotted on a standard cat cortex. There was considerable overlap between groups, and group centroid moved posteriorly for the lower frequencies. Results are in general agreement with Evans et al. [J. Physiol. 179, 238–247 (1965)]. After unit study, some cats were anesthetized and evoked “spikes” from 1×1-mm patches of strychnine-treated cortex were recorded for comparison with unit data. The strychnine-spike tuning characteristics corresponded to those of some but not all units under a patch. [Work supported in part by the Public Health Service, U. S. Department of Health, Education, and Welfare, and by the U. S. Air Force Office of Scientific Research.]
Electrical Stimulation of the Crossed Olivocochlear Bundle: Its Effect on Spontaneous Firings of Auditory-Nerve Fibers
Authors: Wiederhold M. L. , Kiang N. Y. S.
Published: September 2005

In anesthetized cats, the response rate of single auditory-nerve fibers to low-level tones at the characteristic frequency remains markedly reduced during trains of shocks to the crossed olivocochlear bundle (COCB). For most fibers an identical COCB shock train does not result in maintained reduction of “spontaneous” activity. In cats with low thresholds for N1 responses to clicks, fibers with characteristic frequencies within a restricted range exhibit partial suppression of “spontaneous” activity during COCB stimulation. These frequencies are in the most sensitive portion of the cat's audiogram. Our present view is that part of the “spontaneous” activity in these very sensitive fibers represents responses to low-level acoustic noise and can be suppressed by COCB stimulation. Presumably, in less sensitive cats the “spontaneous” discharges of auditory-nerve fibers are not generated by any acoustic input and are not suppressed by COCB stimulation. [This study was supported by grants from the National Institutes of Health and the Joint Services Electronics Program.]
Mechanism of Production of Cochlear Microphonics
Authors: Honrubia Vicente , Allen Stephen , Ward Paul H.
Published: September 2005

The endocochlear potential (EP) was changed by application of extrinsic electric currents across the cochlear partition. When the EP change was sufficient to reverse the dc gradient across the reticular lamina, the cochlear microphonics (CM) reverse their polarity. The size of the CM depended on the magnitude of the dc gradient. The behavior of the hairs on the reticular lamina of the organ of Corti is similar to that of a variable resistor located between the positive EP and the hair cells' negative resting potential. The effective resistance value of this mechanosensitive portion of the cell membrane is approximately 24 000 Ω, and the physiological changes during acoustic stimulation are smaller than ±5%. [Research supported in part by USPHS grants.]
Modes of Auditory Response in the Fissiped Carnivores
Authors: Peterson Ernest A.
Published: September 2005

As part of a program to furnish preliminary but scientifically acceptable estimates of hearing for a broad sample of representative mammals, ac cochlear potentials (CM) were measured in at least one representative from each of the seven fissiped carnivore families. A total of 66 individuals from 12 species were studied. Several response parameters including CM sensitivity level, response bandwidth, and maximum output were used to evaluate peripheral auditory efficiency. It was found that although interspecies differences in performance were great, it was possible to establish common patterns of response. The relation of these groupings to conventional taxonomic classification and to possible artifacts associated with the method of recording will be discussed. [This research was supported by the U. S. Public Health Service under a grant from the National Institute of Neuroogical Diseases and Blindness.]
Changes in the Cochlear Microphonic Resulting from Exposure to a 500-Hz Tone
Authors: Price G. Richard
Published: September 2005

Previous work on the effects of 5.0-kHz stimulation [Price, G. R. (1967). J. Acoust. Soc. Am. 42, 1156(A)] was duplicated on 45 cat ears with 500-Hz stimulation. Changes in cochlear-michrophonic (CM) sensitivity measured at 12 frequencies were the index of loss. Exposure times totaled 80 min, and intensities ranged from that intensity necessary to produce a maximum in CM to 30 dB above that intensity. Data indicate that losses accumulate at a rate that is linear in log time at the lowest intensity and linear in time at the highest intensity. These data are also compared with the previous data regarding the spread of loss within the cochlea.
A Test for Cochlear Linearity from Cochlear Nerve Spike Discharges in Response to Combination Click Stimuli
Authors: Goblick Thomas J. , Pfeiffer Russell R.
Published: September 2005

The interleaving peak structure of poststimulus time (PST) histograms of low-frequency cochlear nerve fiber responses to acoustic clicks of both polarities implies that a cochlear neuron is excited by a damped oscillatory waveform that is half-wave rectified. The oscillatory waveform is presumably related to the impulse response of the basilar membrane and is referred to here as a click excitation function (CEF). For a stimulus consisting of two closely spaced clicks the amplitude and delay of the second click relative to the first click can be adjusted so that one-half cycle of the CEF due to the first click nulls or cancels a particular half-cycle of the other CEF. A null produced in this manner can be detected from the PST histograms of responses of a particular fiber to both polarities of the click pair stimulus. This nulling technique has been used on many cochlear nerve fibers, with characteristic frequencies from 250 to 1700 Hz, to measure the amplitudes of half-cycles of one CEF relative to those of the other to within ±1 dB. If linear superposition of the CEF's due to individual clicks occurs, the null measurements from the PST histograms must satisfy certain self-consistency relations. Thus, this nulling technique provides a means of testing the linear superposition of CEF's that is usually assumed in models of the peripheral auditory system. [This investigation was supported by PHS research grants from the National Institutes of Health.]
Vibration and Galloping of Transmission Lines
Authors: Edwards A. T.
Published: September 2005

Aerodynamically excited vibrations of overhead conductors impose serious economic and operational difficulties on heavy-duty transmission lines. The various types of vibration that are of engineering significance, field observations, and methods of study and of controlling these problems will be reviewed. A full-scale galloping test line fitted with air foils to produce the aerodynamic instability caused by natural icing will be described.
Mechanisms of Flow-Induced Oscillation of Bluff Cylinders
Authors: Parkinson G. V.
Published: September 2005

A lightly damped elastic cylindrical bluff body, with axis normal to an incident flow, may, depending on flow and body parameters, experience one of three forms of transverse oscillation. A cylinder of noncircular section will, over certain ranges of attitude of the section to the flow, exhibit galloping oscillation arising from instability of the dynamical system to the transverse component of fluid force on the cylinder. The oscillation, which can be soft or hard, is analyzed using a quasistatic model and the theory of weakly nonlinear differential equations. Any cylindrical section has a characteristic frequency of wake vortex formation, proportional to flow velocity. At velocities for which this frequency is close to a natural frequency of the elastic system, a resonant vortex-induced oscillation will occur. No satisfactory theory is available, but measurements of surface loadings and wake phenomena during oscillation are providing data on which to build a theoretical model. Any cylinder may experience buffeting oscillations from random turbulent fluctuations in the incident flow and/or the cylinder wake. These oscillations can be analyzed by statistical methods.
Comparison between Measured and Calculated Vibrations of a Reinforced Concrete Building
Authors: Ward H. S. , Rainer J. H.
Published: September 2005

The first four lateral modes and frequencies of vibration of a 15-story reinforced concrete building were obtained from an analysis of wind-induced vibration measurements. The building consists of flat slabs supported on columns and shear walls. Theoretical values of the vibrational modes are calculated using different structural models and considering upper and lower bounds of floor weights and material properties. For some select models, the influence of foundation compliance in the rocking and sliding mode is also investigated theoretically. Results indicate that changes in modal frequencies may be substantial for practically realizable variations in material properties. Measured frequencies of the building fall within the calculated frequency bounds for one particular mathematical model. It is also demonstrated that the frequencies of the lower modes of vibration may be decreased significantly by foundation rocking.
Newborn Infant Cry in Relation to Nonhuman Primate Vocalizations
Authors: Lieberman Philip , Harris Katherine S. , Wolff Peter
Published: September 2005

Cries were recorded from 20 normal newborn infants from birth to the fourth day of life. Sound spectrograms and oscillograms showed that these cries were similar to the vocalizations of nonhuman primates insofar as the infants seemed to produce these sounds by means of a uniform-cross-section, schwalike, vocal-tract configuration. Under certain conditions, the laryngeal excitation was breathy and the formant frequencies corresponding to an open boundary condition at the glottis were generated. The spectrograms reported by Truby, Bosma, and Lind [Newborn Infant Cry] can be similarly interpreted, although they do not do so. Furthermore, their simultaneous x-ray motion pictures show a rigid supraglottal tract during cry, as we hypothesize. The question now is to determine when infant vocalizations become more complex than the basic primate cry. When and under what conditions do infants go beyond the nonhuman stage?
Amplitude Modulations of Sustained Vowels in Patients with Laryngeal Diseases
Authors: Koike Yasuo
Published: September 2005

The amplitude of sustained vowels produced by patients with various laryngeal diseases was measured during 30 consecutive vibratory cycles. Methods of time-series analysis were adopted to analyze the obtained data. It was apparent that patients with laryngeal neoplasms often revealed fairly periodical short-term modulations in the vowel amplitudes, and that most cases of unilateral laryngeal paralysis yielded almost random variations that were not dependent on time. Some of the amplitude modulations were accompanied by perturbations in pitch periods, while others were not related to pitch perturbation. The feasibility and limitations of applying vowel amplitude modulation for the evaluation of pathological conditions in the larynx are discussed.
Linguistic Segmentation of Acoustic Speech Waveforms
Authors: Resnikoff H. L. , Sitton G. A.
Published: September 2005

Time variation of the moments of the distribution of reciprocals of time intervals separating successive zero crossings of the pressure-time speech waveform appearing in a moving 10-msec window are highly correlated with linguistic variations in the signal. Digital-computer analysis of such moments for isolated words uttered in a natural environment shows that fricatives, particularly the /s/ phoneme, are discriminated by the sign of the higher odd moments, whereas nasals and liquids are distinguished by the characteristically constant small values of the even moments. Boundaries for certain phoneme classes can be consistently defined and determined to within 20 msec.
Identification of Vowel Formants in Short Segments of Speech
Authors: Weiss Mark R. , Parsons Thomas W. , Aschkenasy Ernest
Published: September 2005

A study has been made of vowel formant behavior and a method developed for reliably identifying the first three formants from spectra of isolated 24-msec segments of speech. The problem in formant identification is to distinguish each formant from other spectrum peaks, including other formants. This problem is complicated by extensive overlap of the frequency ranges in which formants characteristically occur, and by irregular variations in formant amplitude, particularly during rapid changes in formant frequency. During the study, formant behavior in several thousand spectra was examined. These data were obtained by fine-resolution spectrum analysis of 100 words spoken by five adult male talkers. The study revealed simple relationships between a formant and the amplitudes and frequencies of the largest and second-largest peaks in its frequency range. These relationships can be reduced to a set of rules that are programmable for execution by computer. Such a program has identified formants with an error rate of less than 5% over a set of 1500 words. [This research was supported by Rome Air Development Center.]
Acoustics of the Jesse H. Jones Performing Arts Hall, Houston Texas
Authors: Klepper D. L. , Newman R. B. , Watters B. G.
Published: September 2005

This multipurpose, multiform hall, opened in October 1966, accommodates the full range of musical and theatrical events. The ceiling of the hall consists of an array of hexagon-shaped damped steel panels that can be moved in groups to adjust the hall's seating capacity and its acoustical environment. The ceiling can be lowered to exclude the upper balcony, reducing the seating capacity from 3000 to 2400. Mesh curtains toward the rear mezzanine and orchestra level reduce the seating capacity to 1800. A stage enclosure of damped steel construction can be either 40 ft deep for full orchestra or 25 ft for smaller groups. The reverberation time of the hall at midfrequencies is 1.8 sec in the symphony and opera configurations (3000 seats) and 1.4 sec in the drama configuration (1800 or 2400 seats, all draperies exposed). This paper compares acoustical data obtained in a 110-scale model with measurements in the completed hall.
Acoustics of Northrop Memorial Auditorium
Authors: Ramakrishna B. S. , Smits T. I.
Published: September 2005

This study presents a number of basic acoustical measurements such as the reverberation time, sound-pressure distribution, noise levels, etc., made in the multipurpose Northrop Memorial Auditorium of the University of Minnesota prior to an acoustic remodeling that the auditorium is expected to undergo in the near future. The Northrop Auditorium has a capacity of 4824 seats and has possibly the shortest reverberation time among halls of comparable seating capacity. Some attempts at relating the subjective experiences with the physical measurements will be described. Results of certain trials in designing a centralized proscenium loudspeaker assembly are also given.
Acoustical Performance of Two Music Buildings
Authors: Richards Roy L.
Published: September 2005

Music buildings at Washington State University and Central Washington State College, completed 2 and 4 yr ago, respectively, were the subject of an acoustical study involving measurements and user judgments. Although the two buildings are similar in size and facilities, the acoustical performances are not the same. Each building contains a 400-seat recital hall, but the acoustics of the two are quite different (one is almost twice the volume of the other, 171 000 vs 93 000 cu ft). Data are presented on reverberation time, sound-transmission loss, and background-noise measurements made throughout each building. The teaching staff of both buildings were asked to rate their impressions of the acoustics by completing brief questionnaires. On the basis of questionnaire responses, the original design criteria are examined and some proposals offered.
Acoustical Observations in Greek and Roman Theaters
Authors: Shankland R. S.
Published: September 2005

During the past several years, it has been possible to make acoustical observations in the Greek theaters at Syracuse, Segesta, Agrigento, and Taormina in Sicily, and in the Roman theaters at Ostia Antiqua, Fiesole, and Pompeii in Italy. Articulation tests made in the unoccupied theaters under a variety of conditions and in numerous seat locations show considerable variations in the hearing conditions. It has been possible in some degree to separate the effects of background noise, loudness, directionality, and shape factors on the observed articulation conditions. In several of the more perfect theaters, interesting interference and diffraction effects were observed and studied in some detail. These largely disappear is theaters with less perfect geometry and would be entirely absent with an audience present. However, they provide insight into the special acoustical properties of these structures.
Resonances in the Brass Instruments and the Hand Stopping of Horns
Authors: Backus John
Published: September 2005

Equipment described previously to measure resonances in the clarinet [J. Acoust. Soc. Am. 37, 1203 (A) (1965)] has been applied to the brass instruments. The trumpet shows some 15 resonances; the trombone and French horn show about twice as many. The resonance curves show that the lowest resonance is much too flat to be the fundamental of the harmonic series that the higher resonances approximately fit. Horn players can produce a tone of different quality, called a “stopped” tone, by thrusting the hand as far as possible into the bell. The pitch of the instrument also apparently rises a semitone. Among musicians this is explained erroneously as being due to the shortened air column produced by inserting the hand. Mutes are available that produce, in horns, the equivalent of hand stopping. Such mutes add a considerable acoustic mass to the open end of the horn, and so effectively lengthen its air column, lowering all the resonance frequencies. Resonance curves for a horn made with and without such a stopping mute show that each resonance is pulled down to a frequency that is about a semitone above the unstopped frequency of the next lower resonance. Hence, the apparent result is a rise in pitch of the stopped note.
Subharmonic Excitation—Thresholds and Limits
Authors: Kronauer R. E.
Published: September 2005

In systems with many resonances and some small nonlinearities, it is clear that one excited resonance can directly generate frequency components at multiples of the driven frequency and thereby excite superharmonic resonances. That a similar kind of process can sustain oscillations at frequencies that are fractions of the driven frequency is far less obvious; it is, in fact, necessary to postulate the existence of subharmonic resonances a priori. The physical interpretation of this necessity is that the subharmonics are “hard excited,” requiring an initial threshold stimulus before they can be sustained. Working in the framework of systems with finite degrees of freedom, this paper will examine the process of energy exchange between oscillations and the effects of dissipation and frequency separation on the ability to sustain subharmonics.
Up-Converter Parametric Amplification of Acoustic Waves in Liquids
Authors: Berktay H. O. , Al-Temimi C. A.
Published: September 2005

The parametric amplification of an acoustic wave at its own frequency due to its interaction with a pump wave is found to be impossible in a homogeneous fluid because of the degenerative effects arising from the interaction between the pump wave and the upper-idler. However, a simple approach suggests that up-converter type of parametric amplification can be obtained if an incoming plane wave is assumed to interact with a locally generated high-frequency pump column. In this paper, earlier analyses are extended by using a quasilinear approach in the calculation of the interaction effects, then the effects of extra-absorption occurring at higher intensities are discussed, and the effects due to the shadow of the pump-transducer mounting formed by the incoming plane wave are indicated. Experimental results are in good agreement with the theoretical work and show that up-converter type of parametric amplification can be obtained even at modest pump-wave intensities.
Subharmonic and Other Low-Frequency Emission from Gas Bubbles in Sound-Irradiated Liquids
Authors: Neppiras E. A.
Published: September 2005

When a sound field of sufficient intensity is established in a liquid, the acoustic spectrum recorded on a wide-band microphone contains lines at frequencies below the fundamental (f0) as well as the expected components at harmonics of f0 with (sometimes) white noise. This paper discusses the various ways by which these low-frequency resonances can be generated by oscillations of gas bubbles in the liquid. There appear to be three mechanisms: (1) Integral subharmonics of f0 are generated by oscillations of bubbles whose radial resonant frequencies are submultiples of f0. (2) Bubbles of any size may be shock excited to emit at their radial resonant frequencies. It is shown that large bubbles of certain preferred sizes are normally present, and their resonances may account for other observed low-frequency lines that are not integral submultiples of f0. (3) Possibly, surface oscillations of bubbles contribute to the strong response at the first subharmonic (f0/2). Experimental results justifying these conclusions will be reviewed. [Work supported in part by a grant from National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Virtual Arrays for Underwater Reception
Authors: Berktay H. O. , Al-Temimi C. A.
Published: September 2005

A simple device that utilizes interaction between an incoming signal wave of low frequency and a locally generated high-frequency pump wave to provide highly directional reception is described. The device consists of a pump transducer and of a receiving transducer, which is placed along the acoustic axis of the former. A theory of how the device works is given, in which the study of the nonlinear interaction between the two waves is based upon simplified representation of the pump-field configuration. Results obtained with two experimental models show good agreement with the predictions based on this simplified theory. Considerations affecting the design of a practical device are discussed, and suggestions are made regarding the formation of arrays of such devices for beam shaping, for side-lobe reduction, or for beam deflection.