bluuebunny/crossref_metadata_2025 huggingface dataset:
Hearing and Vocal Output in Mice
Authors: Berlin Charles I.
Published: November 2005

Previous single-unit studies, round-window cochlear potentials, and behavioral audiometry had shown the most sensitive frequencies of moose hearing to lie between 10 and 20 kHz. Analysis of distress calls of normal adult wild and laboratory mice shows a peak of vocal output under stress at 10–12 kHz, with energy present past 100 kHz; most laboratory mice with genes for deafness show reduced ranges of distress-cry output, but with peaks similar in frequency to the normal. However, one strain of congenitally deaf mice (Df/Df) emits calls virtually identical to the normal-hearing mouse, and these calls are sufficient to elicit scurrying behavior from normal-hearing mice. Results are interpreted re: genetic patterns of communication for survival. [Supported by grants from the National Institute of Neurological Diseases and Blindness.]
Some Results from the Normalization of Speaker Differences in a Mechanical Vowel Recognizer
Authors: Hemdal John F.
Published: November 2005

The values of the acoustic parameters of the same phonetic event may vary from speaker to speaker. The absence of invariant parameters in vowel production suggests that a computer program should be self-adaptive in order to recognize the phonetic events of different speech productions. Self-adaptation, however, would be difficult unless phoneme classification could be accomplished through the use of simple boundaries and changes, while maintaining the requisite accuracy. This paper presents data that indicate that vowels may be accurately classified by simple boundaries in the F1-F2 plane, when sufficient control over the production is exercised. This accuracy is maintained from speaker to speaker by small, but important, boundary shifts. These shifts for adaptation to new speakers are determined by simple measurements on a small body of prior utterances produced by the corresponding speaker. Results for 176 consonant-vowel-consonant words produced by six speakers are presented with the rules and measurements for shifting these boundaries and the improvements obtained from them. [This research was supported by the U. S. Office of Education, Cooperative Research.]
Deconvolutlon of Speech
Authors: Oppenheim Alan V.
Published: November 2005

A generalization of the linear-filtering problem has led to a class of nonlinear filters for the separation of multiplied and convolved signals. In the case of convolved signals, the input is transformed by a system φ having the property that the Fourier transform of its output is the complex logarithm of the Fourier transform of its input. After linear filtering, the signal is transformed by the inverse of φ. The objective of this processing is to separate the convolved signals rather than to carry out a detection. Consequently, phase information must be retained, or regenerated by using the Hilbert transform if the signal to be recovered is minimum phase. This processing has been applied to speech to separate the effects due to the excitation and vocal tract. Examples of spectra obtained in this way are used to illustrate the method. [This work is supported by the Joint Services Electronics Program, the National Science Foundation, and the National Aeronautics and Space Administration.]
New Approach to Speech Compression
Authors: Seo Hideo
Published: November 2005

A systematic and quantitative method of computer-synthesized speech for speech-compression research is presented. This paper describes how to increase the communication capacity of the ear as the vital information channel in audio communications. The author presents the technique for the best kind of pitch, loudness, and intelligibility of speech with the advanced systematic approach by sectioning-out portions of phonemes without destroying cognitive qualities by the use of a digital computer. A sample of speech record in regular audio tape is fed to the AD converter through the Direct Data Channel attached to the IBM data-processing system. The digitized data is then analyzed, and the optimum control of trimming-out sections of the above record, by carefully minimizing the transients, is achieved by software programs. The resultant BCD output is subsequently converted to analog data by the DA converter. The associated software, as well as hardware programs, are presented. This work was done in connection with the author's Ph.D. thesis at the University of South Carolina, and the synthesized speech was made at the Computer Laboratory in the Electrical Engineering Department.
Underwater Sound Scattering from a Family of Modeled Rough Surfaces
Authors: Mitchell Stephen K.
Published: November 2005

Experimental measurements have been made of the scattered field of underwater sound from four irregular surfaces which were modeled from pressure-release expanded polystyrene. The first surface, described in a previous paper [“Underwater Sound Scattering from an Irregular Surface,” J. Acoust. Soc. Am. 34, 1240(A) (1966)], is 85×85 cm along the base and has a root-mean-square height of 0.925 cm. Three new models were made. Two differed from the first only in the scaling factor of the vertical dimension; one has a relief of 12 and the other, a relief of 14 the original model. The fourth model has the same vertical scaling as the first, but horizontal scaling twice that of the first; i.e., the base was “stretched” while keeping the heights unchanged. The surfaces were insonified at 100 and 200 kHz by piston transducers having 8° beamwidths; the incident grazing angles were between 30° and 90°. The scattered field was measured at grazing angles from 10° to 100° The results demonstrate the relation between the nature of the surface roughness and the nature of the scattered field. [This work was sponsored by the U. S. Naval Ship Systems Command.]
Range-Doppler Analysis of Underwater Acoustic Backscatter
Authors: Thomas R. S.
Published: November 2005

Experiments have been performed in the deep ocean transmitting CW pulses and detecting backscattered acoustic energy with a narrow-beam transducer situated near the ocean surface. Short-term spectral analysis was performed on the backscattered sound signals and averaging carried out over numbers of samples. Statistical models of reverberation as functions of range and Doppler thus obtained give a measure of the range and radial velocity spread of backscatterers. Samples of surface reverberation exhibit double peaks on the Doppler axis, and some samples of volume reverberation show the existence of ocean current shears with changing depth.
Measurement of the Frequency Spectrum of Pulsed Sine Wave Reverberation
Authors: Garabed Edward P.
Published: November 2005

New signal-processing techniques used in airborne active sonar systems have provided the impetus for this paper. The frequency spectrum of reverberation is needed in order to develop an optimum signal-processing system. A sea test was conducted in a 1500-fathom water-depth area to gather reverberation data. Data were gathered using a vertically directional line transducer at a depth of 60 ft. Reverberation from 1-sec-duration pulsed sine-wave sonar centered at 15.4 kHz was analyzed and the spectrum measured. Average reverberation level as a function of time curves for 100-, 10-, and 1-Hz filter bandwidths are presented. The reverberation spectrum at 2, 3, 4, 5, 6, 7, and 8 sec after the end of the pulse have been graphed and are compared to the pulse spectrum, τ sin(12Wτ)/12Wτ. The verberation spectrum is shown to be significantly wider than the pulse spectrum. The effect of scatterer velocity on volume scattering strength and a general formula for reverberation bandwidth are also presented.
Volume-Scattering Measurements in the Western North Atlantic and Gulf of Mexico
Authors: Van Schuyler Peter
Published: November 2005

Volume-scattering measurements conducted during July 1966 by the U. S. Naval Oceanographic Office are presented for three locations in the western North Atlantic Ocean and Gulf of Mexico. Two-pound explosive charges of TNT, detonated at a depth of 350 ft, were used to investigate the frequency dependence and diurnal variation of volume reverberation levels. Scattering strengths ranging from −48 to −70 dB for each of the three locations are presented as a function of frequency, in 13-oct bands between 2.5 and 20 kHz, and local time. The data show marked frequency-dependent similarities existing in the areas, with the greatest increase in scattering strength occurring below 5 kHz, the maximum diurnal variation occurring at 3.2 kHz, and common peak resonant frequencies observed at 16 kHz during daylight and at both 5 and 16 kHz at night. A comparison with data from an area northeast of Nassan indicates the reported results are an average of about 5 dB higher at night, while daylight scattering strengths show significantly greater values only below 6.4 kHz.
On the Statistics of Ambient Noise
Authors: Arase Elizabeth M. , Arase T.
Published: November 2005

The statistics of ambient noise have been investigated previously for single receivers [A. H. Green, Bell Lab. Tech. Rept. No. 10, (1962)], but no studies were made for ambient noise with arrays. Data are presented for ambient noise measured with 30- to 60-element arrays. Amplitude samples of ambient noise were taken at 30-msec intervals. The period is long enough to ensure that successive samples are independent. Sets of 2000 to 3000 points were taken, making the time for each set short enough that the noise can be assumed to be stationary over this period. Noise statistics were also taken with random addition of the elements. No significant difference was found for the statistics of the two cases. Distribution functions and moments up to the fourth order were computed and will be presented. [Hudson Laboratories of Columbia University Informal Documentation No. 126. This work was supported by the U. S. Office of Naval Research.]
Electronic Suppression of Reverberation
Authors: Schroeder M. R.
Published: November 2005

Several methods for electronic processing of reverberant sound signals to suppress echoes and reverberation are discussed. Potential applications of these methods in sound reinforcement, conference telephony, and underwater speech communication are described. The implications of a recently proposed self-adaptive echo canceler [M. M. Sondhi, J. Acoust. Soc. Am. 40, 1255(A) (1966)] for improving the stability of sound-reinforcement systems are considered.
Instrumentation Role in the Observation of Geoacoustical Phenomena from Artificial Sources
Authors: Fehr Uri
Published: November 2005

Many physical principles have been applied to transform atmospheric-pressure fluctuations 1 sec and longer into electrical signals for the purpose of monitoring infrasonic signals. A survey of some infrasonic sensors is taken, with calibration and testing of several at the UCLA calibration facility. An attempt was made to define the capabilities of each available sensor. Several experiments are described, which include the monitoring of static and dynamic firing of rockets as well as that of explosions. The difficulties in interpretation of data are explained in relation to various instruments, taking into account wind effects, ground vibrations, natural pressure fluctuations, and other phenomena producing noise at the frequency range of interest.
Investigation of the Nature and Source of Infrasonic Noise in a Wind Field
Authors: Maxwell Gerald G.
Published: November 2005

The nature and source of infrasonic noise in a wind field is investigated by means of pressure cross-correlation measurements. The work is accomplished in two parts, Phases A and B. The results of Phase A indicate that, when a wind field is measured by a microphone, the dominant part of the noise detected is caused by the microphone disturbing the wind flow. The cross-correlation coefficient is shown to be a function of the separation between the microphone ports, the frequency of turbulence, and independent of the wind speed. As a result of the conclusions on Phase A, windscreens were developed to reduce the flow noise; and Phase B covers investigation of the wind field using multiple windscreens. These devices reduce the noise as much as 18 dB at wind speeds of 5 mph. It is shown that a small part of the noise under the windscreens is still generated by the flow, but it is evident that the remainder of the pressure fluctuations are caused by turbulent pressure calls that move along with the wind flow.
Three-Dimensional Imaging of Sound Fields by Bragg Diffraction of Light
Authors: Korpel A.
Published: November 2005

A discussion is given of the image-forming properties inherent in the process of light-sound interaction. It is shown that, in certain configurations, the diffracted light carries all the information necessary to image the sound field in amplitude and phase. Experimental techniques are discussed and results presented which were obtained with an experimental ultrasonic microscope operating at 24 MHz.
Sound Holography and Optical Reconstruction
Authors: Mueller R. K.
Published: November 2005

Image formation and sound holography for general wave fields are discussed to provide the background for the discussion of acoustic holography, which covers the following aspects: acoustic holography by scanning methods, nonacoustic recording of acoustic holograms, the surface as a recording medium, surface response to sonic radiation pressure and its application to real-time holography. Problems connected with optical reconstruction of acoustic holograms and potential applications of acoustic holography.
Velocity Dispersion in Liquid Benzene at Ultrahigh Frequencies
Authors: O'Connor C. Leonard , Schlupf Joseph P. , Stakelon Thomas S.
Published: November 2005

Measurements of the Doppler shift of Brillouin components in the scattering of radiation from a 75-mW gas laser operating at 6328 Å were made in liquid benzene at 20°C. An experimental system was designed to allow velocity measurements to be made over a substantial portion of the dispersion region, namely, from about 0.6 to 6.0 Gc/sec. The scattered radiation was analyzed by a pressure-scanned Fabry-Perot interferometer with a finesse of about 60. The plate separation was varied with each scattering angle such that the spectral range of the interferometer was close to three times the separation of the central unshifted line and one component of the Brillouin doublet. The experimental results, in terms of the intensity ratio IC/2IB and the velocity measurements, are compared with those predicted by Mountain and Kneser. More recent spectroscopic data have been used to evaluate the upper limit of the dispersion curve.
Accuracy and Precision of the Stimulated Brillouin Technique for the Measurement of Hypersonic Velocity in Liquids
Authors: Goldblatt Norman , Litovitz T. A.
Published: November 2005

Experiments by several investigators seem to indicate the possibility that the technique of stimulated Brillouin scattering (SBS) in fluids do not yield the same results for hypersonic velocities as predicted either by theory, CW-laser, or standard ultrasonic techniques. The possible sources of these discrepancies will be considered. A practical experimental arrangement using SBS that yields a precision of better than ±0.5% is described. Although a systematic deviation exists, the data agree with accepted values in water to within the above limits. Data in other liquids and in gases are also considered. A comparison of the usefulness of CW and pulsed-laser techniques for the measurements of hypersonic velocity will be presented. [Work supported by the U. S. Atomic Energy Commission.]
Derivation of the Velocity and Absorption of Sound in Liquids at Gigacycle Frequencies from Analysis of Brillouin Spectra
Authors: Piercy J. E. , Hanes G. R.
Published: November 2005

Brillouin spectra of light scattered by thermal fluctuations in an acoustically relaxing medium have been calculated from molecular parameters using (a) normal three-component acoustic theory, (b) acoustic theory assuming temporal decay, (c) Mountain's new theory. Relative to Theory (a), Theory (b) predicts a smaller Brillouin displacement in the relaxation region. Theory (c) predicts an even smaller displacement that is dependent on the apparatus profile because of assymetry in the Brillouin component. The shift is in a direction to reduce the discrepancies described in the literature between the dispersion derived from Brillouin spectra and that expected for vibrational relaxation. It also appears to eliminate the discrepancies indicated by our measurements of 90° scattering in mixtures of benzene with toluene, which correspond to f/fr ratios of 0.5 to 7 for the benzene-toluene system. A plausible, simple mechanism for the fourth component of Mountain is introduced to explain the nature of the additional shift introduced by Theory (c).
Measurements of Earphone Voltage at Hearing Threshold and Earphone Pressure at Ear-Canal Entrance
Authors: Shaw E. A. G.
Published: November 2005

The special earphone described earlier (five driver units in a circumaural enclosure) has been used to determine hearing threshold levels of from 1 to 16 kc/sec for 3–6 subjects. Changes in driver voltage at hearing threshold and ear-canal pressure response levels with repeated measurements may be related to three mechanisms. (1) Changes in earphone-ear coupling account for most of the apparent changes in hearing threshold above 4 kc/sec (e.g., standard deviation 5 dB at 8 kc/sec). (2) Apparent changes in earphone response are attributed to probe-tube position errors at certain frequencies (5 and 10 kc/sec). (3) Threshold changes attributable to the subject average 2 dB at all frequencies with a 5–15-day interval between measurements.
Diver Positioning Response System (DPRS)
Authors: Thompson C. L. , Hollien H.
Published: November 2005

A system is described that provides a rigorously controlled milieu within which the testing of hearing and speaking functions underwater can be accomplished. Provisions are made for (1) the presentation and reception of acoustic stimuli, (2) the transmission of visual material for use either as multiple-choice hearing-test response items or as test material for studies of speech production, and (3) the transmission of multiple choice responses by the subject to a digital (IBM) surface control unit. Research is currently in progress utilizing this unit (DPRS) in (1) the evaluation of normal hearing thresholds for pure tones and speech, (2) evaluating diver's capabilities to speak underwater, and (3) evaluating commercial underwater speech-communications systems. [This research is supported by a grant from the Physiological Psychology Branch of the Office of Naval Research.]
“Polyacusis” Accompanying Hearing Loss
Authors: Corliss Edith L. R. , Burnett Edwin D. , Stimson Harold F.
Published: November 2005

During audiometric test, H. F. Stimson observed that signals of above 3500 Hz produced different pitches in his right and left ears; the right ear's sensation was appropriate to a lower frequency. Upon raising the level, the pitch perceived in the right ear persisted, but another tone appeared. Further investigation of the right ear showed: Above 3700 Hz these tones remain fixed, independent of the frequency of the stimulus that evokes them. Pitch matches can be made either via the left ear, or by additional stimulus at the right ear, but no beats are heard. The tone perceived above threshold is matched by about 2200 Hz. At higher levels, an additional tone corresponding to 1400 Hz appears, and at still higher levels, one corresponding to 1700 Hz. Frequency matches were reproducible within 2% even over weeks. The absence of beats, the tonal purity and constancy of the spurious responses, and their coincidence with pitch sensations evoked by signals of lower frequency imply that the effect originates in a mechanism beyond the cochlea.
Joint Acceptance for Cylinders
Authors: Wenzel Alan R.
Published: November 2005

A theoretical analysis of the response of a thin cylindrical shell to a random loading is given, and equations defining the joint acceptance for a cylinder are derived. The governing equations of motion are taken to be the Reissner shallow shell equations, which are written as a single matrix equation. The solution gives the spectral density function of both the radial displacement and stress function in terms of the normal modes of the cylinder and the spectral-density function of the external pressure field. The final equations involve an external-pressure-structural-mode coupling term similar to the joint acceptance as defined by Powell, which then serves as the basis for defining the joint acceptance for a cylinder. Utilizing previous results obtained by the author, the equations derived in the text are applied to the case of a cylinder in a diffuse sound field. [This work was supported by National Aeronautics and Space Administration.]
Modal Analysis of the Response of Structures to Nonhomogeneous, Nonstationary, Random Fields
Authors: Lennox W. C. , Beer F. P.
Published: November 2005

Extending results obtained by Powell [Random Vibrations (MIT Press, Cambridge, Mass., 1958)], the generalized power spectrum of the response y(x,t) of a linear structure to a nonhomogeneous, nonstationary, random field f(x,t) is expressed as φyy(x ; ω1,ω2) =  ∑ m,n ψm(x)ψn(x)Hm*(ω1)Hn(ω2)φm,n(ω1,ω2), where ψm is a mode shape, Hm the corresponding frequency response function, and φm,n the generalized cross-power spectrum of the inputs to the modes m and n. The latter is expressed as ψm,n(ω1,ω2) = 1(2π)2 ∫∫−∞∞ Ψm*(k1)Ψn(k2)Φff(k1,k2,ω1,ω2)dk1dk2, where k is a wavenumber, Ψm the Fourier transform of ψm, and Φff the generalized power spectrum of the input field. Remarkably simple expressions are obtained for the mass and time averages of φyy.
Transient Axisymmetric Motion of a Finite Thick Hollow Elastic Cylinder
Authors: Cinelli G. , Pilkey W.
Published: November 2005

Using the dynamic displacement equations of elasticity for axisymmetric motion, normal mode solutions are found for the transient displacements and stresses in a finite thick hollow elastic cylinder when all of its surfaces are subjected to loads which are arbitrary functions of space and time. It is shown how these solutions are obtained by means of finite integral transforms, which, in turn, are derived from the solution for the corresponding eigenvalue problem. The surface tractions are specialized to standard forms such as an impulse, sinusoid, etc., which enable the free, harmonic, and static motions to be recovered. Physical quantities such as resonance and mechanical impedance are derived and studied. Next, plane-strain motion is obtained from the general solutions as a special case. Problems in numerically evaluating the eigenvalues are discussed. [Work partially supported by the U. S. Atomic Energy Commission.]
Spherical Radiator Encased in a Thick Shell
Authors: Molloy C. T. , Yeh G. C. K.
Published: November 2005

Transmission of sound waves from a spherical transducer through a fluid medium and a concentric viscoelastic shell to a fluid medium of infinite extent has been analyzed. Formulas for the acoustic field when the transducer is driven with constant amplitude, sinusoidal radial velocity, have been derived. The shell is considered to be a viscoelastic medium, and the approximations of thin-shell theory have not been used. The formula for the insertion loss due to the presence of the shell has been derived and programmed on a digital computer. Numerical results show that the insertion loss is an oscillatory function of frequency, indicating the existence of regions of favorable and unfavorable transmission, which are primarily controlled by the transducer-shell spacing. The magnitudes of the maxima and minima of the insertion loss are determined primarily by the mass per unit area of the shell. The insertion loss function does not depend strongly upon the elastic constants or the material dissipation of the shell. [Work supported by U. S. Navy Ordnance Systems Command.]
Experimental Evaluation of Signal Processing Techniques for Reverberation-Limited Sonar
Authors: Muir T. G. , Allen D. A. , Wunderlich K. W.
Published: November 2005

The results of resolution experiments on several signal processors is discussed. Echo-ranging data were taken with an experimental sonar in the presence of reverberation in order to evaluate several signal processing schemes thought to improve sonar resolution. These schemes include multiplicative processing, sum-difference additive procession, and Dolph-Tschebyscheff shading. The dependence of the echo-to-reverberation ratio on azimuth for a single target in a backscattering environment was studied. The two-target resolution capability of these processors was also studied. Data obtained from these measurements are compared to those obtained from the experimental sonar with no such processing. The results are interpreted to demonstrate how increased resolution may be achieved for reverberation limited echo-ranging applications. [This work was sponsored by the U. S. Office of Naval Research.]
New Tenor Violin
Authors: Hutchins Carleen M.
Published: November 2005

The early tenor violin (TENORE, to hold), tuned approximately 1 oct below the present violin, carried a prominent part in early polyphonic music where its counterpart in the viol family had been used extensively. Thus the gradual suppression over the last 200 yr of the tenor voice in the violin family seems a strange deficiency, since the true tenor tone color is not adequately replaced by either the violas or the violoncellos. A possible explanation is offered for the demise of the tenor due to relative dimensions in early tenors and 'cellos, and the resultant tone quality based on placement of resonances. These factors will be discussed and demonstrated on the tenor and baritone instruments of the new violin family, and on a conventional 'cello. [Work supported by the John Simon Guggenheim Memorial Foundation, the Martha Baird Rockefeller Fund for Music, and the Catgut Acoustical Society.]
Resonances in the Bassoon
Authors: Backus John
Published: November 2005

Resonance frequencies in the bassoon have been plotted with the equipment, previously described [J. Acoust. Soc. Am. 37, 1203 (1965)], which simultaneously draws on a strip chart the resonance curve of the instrument under external excitation and a plot of the positions of the harmonics of the fundamental frequency (the frequency of the lowest resonance). Curves for the low register of the bassoon show that the two resonances above the lowest are close to but above the second and third harmonics. Higher resonances agree only fortuitously with harmonic frequencies. In the middle register of the instrument, which is produced in playing by opening small holes at appropriate places and thus destroying the lowest resonance, the relationship between the resonances and the harmonics seems to be completely random. It is found that over much of its range the instrument plays below the frequency of the lowest resonance by more than a semitone. This worsens the agreement between the resonance frequencies and harmonics of the playing frequency.
Measured End Corrections for Woodwind Tone-holes
Authors: Benade A. H. , Murday J. S.
Published: November 2005

Impedance parameters of a tone-hole system are expressible in terms of geometrical hole lengths L plus added end corrections. These were estimated from frequency measurements on resonators. Account was taken of boundary-layer effects, which are small above 300 Hz. For a hole or tube of radius b, each correction is of the form ΔL=b⋅E, where E depends on the end geometry. For a tube whose flange has an outer radius (b+w), the measured end correction is Et=0.821−0.13[(w/b)+0.42]−64. A disk of radius r placed normal to the tube axis at a distance h from its end (e.g., a pad poised over its tone hole) gives Ed=0.61(r/b)0.18(b/h)0.39 for 1≤(r/b)≤4, provided Ed≥0.65. For a hole of radius b drilled through the wall of a pipe whose outside radius is R, the outer-surface correction is E0=0.64[1+0.32ln(0.3R/b)] for 1.5≤(R/b)≤7. The inner-surface correction for this hole is found using a doubly closed resonator tube of inside radius a and of variable length, into whose side is inserted an open side-branch of variable length and radius. The inner correction at 300 Hz is Ei=[1.3−0.9(b/a)] for (b/a)≤0.72.
Shadowgraph Visualization of Jet Noise
Authors: Lowson M. V. , Ollerhead J. B.
Published: November 2005

Shadowgraph visualization of supersonic jet flows can reveal both the flow structure and acoustic field of the jet. The acoustic field takes the form either of Mach waves or of a spherical radiation centered on points near shock intersections in the supersonic jet flow. Several shadowgraph pictures of cold supersonic jets are presented to demonstrate different facets of the flow field and to show the importance of film-to-flow distance on resolution. From the pictures, it appears that a major part of the observed noise field arises from shock interactions within the jet. [Work supported by the National Aeronautics and Space Administration.]
Acceptable Noise Exposures
Authors: Botsford James H.
Published: November 2005

A simple method for determining permissible noise exposures has been developed from the NAS-NRC CHABA report [Kryter, Ward, Miller, and Eldredge, J. Acoust. Soc. Am. 39, 451–464 (1966)]. The data of this report imply that the susceptibility of the ear to noise injury varies with frequency in the same manner for steady, varying, and interrupted noise. Utilizing this property, nine contours of equi-noxious octave-band sound-pressure levels were defined and, for each, the total noise duration permissible daily was calculated for various numbers of periodic interruptions. This total noise duration increases rapidly with the number of interruptions, passes through a maximum value for interruptions about 5 min in length, and becomes constant for noise bursts shorter than 2 min. Five hundred eighty typical manufacturing noises were sorted into ten groups by the octave-band levels of the nine contours and an A-weighted level was then assigned to each contour so that the sorting of the noises using this measure most nearly duplicated that obtained using octave bands. The results indicated that acceptable noise exposures can be identified as accurately using A-weighted levels as can be done using octave-band levels.
ROC Curves for Multiple-Signal Levels in a Detection Task
Authors: Tucker Ann , Evans Rand B. , Jeffress Lloyd A.
Published: November 2005

Seven signal levels were presented to four observers in a pseudorandom fashion. A 500-Hz tone was used, and the signal duration was maintained at 100 msec with a rise-decay time of 10 msec. Wide-band (100–3000 Hz) continuous noise was used as the masker. The listening interval was indicated by a light, and observers were instructed to clarify or rate the loudness of the masked signal by using one of 10 ordered push buttons. On some trials noise alone was present; on the remaining trials (2E/N0)12 ranged from 2.0–5.0. Receiver operating characteristics were plotted for each signal level, and a remarkably small number of trials was needed to yield satisfactory curves. The multiple-level rating procedure yields smooth curves for seven signal levels in about the same time previously needed for only one level. The observer's task, to rate the loudness of the stimulus, appeared to be simpler than that of earlier studies, in which he was asked to rate his “certainty” that a signal was present. [Work supported by a contract with the Naval Ship Systems Command, Department of the Navy, and through a grant from the National Aeronautics and Space Administration.]
Time Uncertainty in 2AFC and 4AFC Experiments
Authors: Main Dana B. , Tanner Wilson P. , Rivette C. Laurence
Published: November 2005

In the four-alternative forced-choice (4AFC) experiment, one of the following four acoustic-signal alternatives was presented with equal probability in a single observation interval to three observers: two signals 12 sec apart, denoted 11; one signal near the beginning of the observation interval, denoted 10; one signal near the end of the observation interval, denoted 01; no signal, denoted 00. Six 2AFC experiments were completed on the same observers in which each alternative was paired with every other alternative: 11-00; 10-01; 11-01; 11-10; 10-00; and 01-00. The data have been analyzed within the framework of the theory of signal detectability. The boundaries of decision spaces were determined by using d′ from the 2AFC data. A technique for defining the decision space from the 4AFC data is presented. The relationships between the decision space from the 2AFC and 4AFC within an observer and from the human observer to the ideal observer are discussed. [The research for this paper was supported by the Advanced Research Projects Agency, Assistant Director, Behavioral Sciences, Command and Control Research, and was monitored by Behavioral Sciences Division, Air Force Office of Scientific Research, under contract.]
Implications of a Hypothetical, Varying Threshold for Models of Binaural Masking
Authors: Hafter Ervin R. , Dolan Terrence R.
Published: November 2005

Attempts have been made to explain “binaural trading ratios” by proposing that amplitude is converted to time by a peripheral threshold sensitive to the slope of the acoustical waveform. Such a mechanism also has implications for explanations of binaural-detection phenomena. Models which attempt to account for these phenomena on the basis of an interaural time shift are inadequate for conditions in which the noise differs in interaural level. This problem shows up clearly in cases where detectability varies with the level of noise at the nonsignal ear. Time-shift models do not predict this reduction in detection, since the decreasing noise level at one ear does not affect the magnitude of the interaural shift of time. If the acoustical-to-neural transfer function involves a varying threshold, the reduction of noise in the nonsignal ear results in an increase of variance of interaural time shifts due to noise alone; this in turn leads to decreased detectability of the time shifts owing to adding signal at one ear. Computations supporting this view are presented.
Effect of Relevant Cues on Attention in Binaural Listening
Authors: Durrant John D.
Published: November 2005

Several experimenters have demonstrated the importance of the relevance of information in complex listening situations. However, in general, these experimenters have concerned themselves mainly with the decremental effects of irrelevant information on task performance and attention selection of one of two competing messages. The present writer is concerned with the influence of relevant information, i.e., the effects of inserting relevant cues into irrelevant information presented at the nontest ear. Twenty-three college students (experimental group) were given an intelligibility test under this condition—i.e., word lists presented at one ear and irrelevant contextual speech, with inserted cues, at the other ear. Twenty-nine college students received the same test under the same condition, but without the cues. The attention selection of the cues significantly improved the scores of the experimental group over those of the control group. Various operant factors in the test situations with their “real life” analogs are discussed. The results of this study are discussed in relation to Deutsch and Deutsch's theories of attention.
Some Observations of Laryngeal Phenomena Derived from High-Speed Motion Pictures
Authors: Soron Henry I. , Michaels Sheldon B. , Lieberman Philip
Published: November 2005

The activity of the larynx was photographed by a Fastax high-speed camera during the production of short, normal vowels; short, breathy vowels: tense and lax glottal stops; and the VCV utterance /ɛhɛ/. During the breathy vowel the arytenoids are separated. A triangular aperture is thus formed at the posterior portion of the glottis in contrast to the complete closure typical of normal vowels. The glottal stop is produced by the contraction of the sides and anterior of the larynx at and below the level of the false vocal cords. During the closure of the tense glottal stop some vocal cord motion was observed. The rate of closure and relaxation for the tense and lax glottal stops appears to be approximately constant. The pattern of laryngeal activity for both vowels of the utterance /ɛhɛ/ differed from that typical of normal short vowels insofar as vocal cord motion started before closure of the arytenoids, giving a breathy effect.
Study of Voicing in Initial Stops Found in the Prelinguistic Vocalizations of Infants from Different Language Environments
Authors: Preston Malcolm S. , Stark Rachel E. , Yeni-Komshian Grace
Published: November 2005

Recent work at Haskins Laboratories suggests that the time interval between the release of air pressure and the onset of voicing is an effective measure for sorting initial stops into phonemic categories. In general, it appears that three positions along the continuum of voice-onset time may be utilized: 70–100-msec voicing lead; 0–30-msec voicing lag; and 50–110-msec voicing lag. English utilizes the two voicing-lag positions while Arabic makes use of the voicing-lead and short-voicing-lag positions. This paper reports the results of a cross-language study of voicing in initial stops occurring in the prelinguistic vocalizations of three English and three Arab infants all between 11 and 14 months of age. In addition, data obtained six months after acquisition of a hearing aid are presented for two 24-month-old severely deaf English children. (Investigation supported in part by the National Institute of Child Health and Development.)
Effect of Gas Constants on Voicing Frequency
Authors: Michaels Sheldon B. , Wathen-Dunn Weiant
Published: November 2005

It is well known that the composition of the exhaled gas has no large effect on voicing periodicity but, so far, the question of small effects has been left open. Mathematical models of vocal-cord action, though admittedly imperfect, nevertheless indicate, by virtue of the fact that the expressions contain gas constants, that some effects might be expected to occur. However, the results of experiments to detect such effects are too greatly influenced by talker variability when conversational speech is used as the test material. The present paper describes an experiment designed to reduce the effect of talker variability. The subject is presented with a complex tone through earphones. It is his task to match the frequency of the tone vocally, but after it has been removed and noise sufficient to mask his own performance substituted on the earphones. Under such conditions, the usual auditory feedback is lacking, and only proprioceptive feedback is available to position and tension the vocal cords. Preliminary results from measuring voicing frequency with various gases will be reported.
Application of a Head-Contact Microphone to Hands-Free Speech Communication under Hazardous Conditions
Authors: Sebesta George J. , Mellen Arthur J. , Hofer Alan
Published: November 2005

Speech communication is required in certain hazardous conditions where the hands must be left free, such as military operations involving searching tunnels and operation of open vehicles such as a motorcycle. A compact field telephone has been developed for the former application, utilizing a head-contact inertia-operated microphone and logarithmically responsive amplifier. These components and a battery are assembled on a specially-designed cap. A reel carrying a half-mile of disposable cable is worn on the belt. The microphone is of the variable-reluctance balanced-armature type. The components are described.
Wave-Induced Fluctuations in Shallow-Water Sound Propagation
Authors: Westervelt P. J. , Halpin H. , Williams A. O.
Published: November 2005

Relative fluctuations ΔI/I of acoustic intensity, caused by surface-wave patches passing over a source and receiver bottom in shallow water, are analyzed theoretically and compared with Scrimger's measurements [J. Acoustic. Soc. Am. 33, 239–247 (1961)]. A patch is treated as an acoustic dipole, driven by the primary source-image field, and reradiating to interfere with the main signal. ΔI/I depends on wave height A, acoustic wavelength λ, and the patch's position along a horizontal line directly over source and receiver. For Scrimger's longer wavelengths, the following agreements with experiment appear—A/λ is a major but not sole parameter; ΔI/I∝A (λ fixed); ΔI/I varies linearly to quadratically with 1/λ (A fixed; ΔI/I is greatest for patches practically over source or receiver, least at midrange; ΔI/I has fundamental frequency equalling that of a train of patches. Combining patches into wave trains appears necessary, but may not be sufficient, to calculate absolute magnitudes and to explain, at larger A/λ, saturation of ΔI/I and appearance of harmonics in its frequency spectrum. [Supported in part by U. S. Navy Office of Naval Research.]
Acoustic Propagation in a Continuously Refracting Medium
Authors: Ai D. K. Y. , Solomon L. P.
Published: November 2005

To calculate acoustic-ray paths in the ocean, it is essential to know the speed-of-sound variation with depth. Generally, linear- or quadratic-curve fits to experimental points are used. This leads to models with as many as 150 layers. The solutions are purely numerical in character. This paper proposes a three-layer model in which each layer uses an analytic expression for the speed of sound variation. This results in analytic, easily handled expressions for the ray paths. The speed of sound and its first derivative are matched at each layer interface; the depth of each layer is adjusted, dependent upon the experimental points. The upper layer is either a quadratic or cubic polynomial, the middle layer is a hyperbolic cosine, and the lower layer is linear. The model includes reflections from arbitrary analytic bottoms and flat ocean surfaces. The computer is used purely for computational results, not for integration. This theory may be considered as a “zeroth”-order analytic solution for more complex propagation models.
Omnidirectional Scanning and Relief Presentation for Ultrasonic Visualization of Intracranial Anatomy
Authors: Fry William J.
Published: November 2005

The application of new scanning (omnidirectional), echogram composition (band assembly), and display (relief presentation) methods to the ultrasonic visualization of intracranial anatomy is described. These methodologic advances are implemented by a general purpose on-line digital computer that makes possible a flexible approach to the development of a more sophisticated generation of such instrumentation facilities. At this stage of the evolution of instruments for viewing the brain, it is desirable to separate certain problems specifically associated with transskull operation from those concerned with determining what anatomic features can be detected and localized when examining pulses are employed in the absence of enhancement of impedance differences at interfaces and under the condition that the acoustic energy not traverse bone. Results for rhesus monkey brain in vivo under such experimental conditions are illustrated.
BUDTIF Thresholds: Variability and Bias
Authors: Campbell Richard A.
Published: November 2005

Threshold determination with the block up-and-down, two-interval forced-choice (BUDTIF) method has been investigated by obtaining 10 repeated 75% correct thresholds from human subjects. Major parameters were number of trials per block (2, 4, and 8) and number of trials per threshold (16–144). Measures of within- and between-day variability and within-run variability were closely related to one another and were generally inversely related to block size and number of trials per run. The effect of number of trials on variability with a block size of four trials was minimal however. For example, the mean between-day standard deviation was 0.80 for 32 trials and 0.73 for 144 trials. Mean thresholds were directly related to block size, as one would expect from the binomial bias. Thresholds also tended to become lower with increased trials per run. Efficiency was generally inversely related to trials per run and directly related to block size, although the trends are somewhat mixed. The variability observed in these data differ from that observed in stimulated listeners. This is interpreted to indicate that the assumption of trial-by-trial independence in human observers is much less tenable than commonly asserted.
Experimental Study of Aerodynamic Sound from a Rotating Disk
Authors: Chanaud Robert C.
Published: November 2005

The broad-band sound generated aero-dynamically by a smooth disk rotating in its own plane was measured. The low-frequency part of the spectrum was caused by vortex formation at the disk edge, and appeared acoustically as a point pressure dipole on the disk axes and aligned with the axis. The high-frequency part of the spectrum was caused by the interaction, with the disk edge, of the boundary layers on both faces and on the periphery. The location of the effective source moved closer to the edge with increasing frequency, and was pressure dipole in nature. Addition of a sandpaper ring to both faces caused generation of high-frequency sound at the point of roughness as predicted by [J. Acoust. Soc. Am 37, 516–522 (1965)]. Acoustically, the source appeared as dipoles whose axes were about 70° to the axis. Edge and roughness caused sounds are exceptions to the concept that surface dipoles account only for reflection of quadrupole sources [Powell, J. Acoust. Soc. Am. 32, 982–990 (1960)].
Right-Angle Reflector Technique for the Ultrasonic Examination of Material Properties
Authors: Rollins Fred R. , Levy S. L.
Published: November 2005

An ultrasonic goniometer is described that utilizes a single transducer and a reflector composed of two plane orthogonal surfaces. With the instrument immersed in a suitable coupling liquid, the transducer rotates about an axis colinear with the intersection of the orthogonal surfaces. The amplitude of the reflected signal is automatically recorded versus the angle of incidence measured relative to one of the reflector walls (the removable specimen). Amplitude variations can be related to the excitation of surface waves, Lamb waves, critical refraction conditions for body waves, and other physical properties of the reflecting surfaces. The instrument has been extremely useful in measuring surface wave velocities for both single crystal and polycrystalline specimens. On copper and quartz single crystals, good agreement has been achieved with theoretical predictions of surface wave velocity as a function of propagation direction. [Phys. Rev. 119, 533 (1960); J. Acoust. Soc. Am. 41, 921 (1967)]. The sensitivity of the device to other physical parameters will be discussed. [Work supported in part by the Office of Naval Research].
Subharmonics Generated by Bubbles in Sound Fields
Authors: Neppiras E. A.
Published: November 2005

Measurements have been made of the acoustic output from isolated air bubbles in water and glycerol-water mixtures subjected to sound fields. A mechanical device has been developed for generating small bubbles of uniform size at a controlled rate. The bubbles are allowed to rise along the axis of a radial-focusing transducer capable of operating over a wide frequency range (10–60 kc/sec) at intensities up to the cavitation threshold. It is found that driven at twice their natural radial resonant frequency may emit a strong signal at half the excitation frequency. A weak emission at the subharmonic is observed even at low drive intensities. At a certain threshold, often well below the threshold for transient cavitation (estimated from white noise), the response suddenly increases, and may remain at a high constant level for many cycles. At the cavitation threshold, the output becomes intermittent, and other bubbles are formed and emit, along with a large increase in white noise. The indications are that nonlinear radial vibrations contribute most to the subharmonic response. [Work supported by a contract from National Institutes of Health, U. S. Department of Health, Education, and Welfare.]