bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Finite Element Model for a Guided Spherical Shell
Authors: Georgopoulos G. , Royster L. H.
Published: October 2005

A doubly curved anisymmetric spherical-shell finite element is utilized in order to predict the dynamic response of spherical shells for the Class V flextensional underwater acoustic transducer. The spherical shell is represented as a finite number of spherical frustra, joined at nodal circles. Norozhilov's “Thin Shell Theory” is applied and the element stiffness and mass matrices are derived and numerically integrated by utilizing Gauss-Legendre polynomials. The frequency coefficients of a spherical shell are defined. An IBM 360/75 computer is used for obtaining numerical results for varying thickness and opening angle, with guided clamped, guided pinned, clamped, and pinned boundary conditions. Numerical results for the Class V flextensional underwater transducer shell are included. Finally, a convergent test is carried out for a different number of finite elements for the Class V flextensional underwater transducer shell having pinned boundary conditions. The results agreed almost perfectly with earlier results obtained experimentally.
Underwater Modulation Effects
Authors: Hayre H. S.
Published: October 2005

The use of Kirchhoff-Huygens' integral is made to show that both amplitude and angle modulation are produced by the relative motion of the signal source and the randomly scattering ocean surface or the target with its associated random medium effects. Furthermore it is shown that these two modulation effects are statistically dependent. The case of a Doppler system where the amplitude modulation effects are essentially eliminated by hard limiting is studied. Therefore the dependence of the Doppler signal spectrum and its bandwidth on the surface roughness, as well as the angle of incidence, are derived for an operational frequency of 50 kHz. The cases of one-dimensional isotropic surfaces, as well as surfaces with along- and cross-wind, statistically independent, spatial height correlation functions are considered. The results are expressed in empirical forms to show their usefulness to system designers and operational personnel.
Doppler Spreading of Reverberation in Shallow Water
Authors: Ross J. M. , Brochu C.
Published: October 2005

Reverberation data have been gathered with a narrow-beam transducer, which transmitted a 1.4 sec CW pulse at 9.5 khz. The transducer was towed through the waters of the Scotian Shelf and Gulf of St. Lawrence at various depths. Conditions exist in these relatively shallow water areas where surface, volume, and bottom are all, at different times, the dominant backscattering mechanism. In winter, because of the typically strong positive thermal gradients, surface reverberation dominates. In summer, two common situations exist: (1) a strong negative gradient, where bottom is the dominant backscatterer, and (2) a pronounced sound channel where volume may be the dominant backscatterer if leakage is small. If sufficient leakage occurs, contributions from bottom and volume reverberation can both be significant. When surface reverberation dominates, spectral bandwidths are a function of the sea surface conditions. When bottom reverberation is dominant, the spectral spreading is greater than that associated with the system resolution, probably due to variations in shear currents. The spreading associated with volume reverberation lies between that of bottom and surface backscattering, but the scattering strength is significantly lower.
An Acoustic System for Measuring the Waveheight of Sea Surface Waves
Authors: Roderick William I.
Published: October 2005

An upward-looking echo-sounder system has been designed to measure the time varying waveheight of sea-surface waves. A narrow beam of pulsed acoustic energy was focused on the sea surface by utilizing the transitional region from the near to farfield characteristics of a circular piston transducer. The transducer, operating at 360 kHz, was pulsed at 10-msec intervals to sample the waveheight. By transmitting short pulse lengths, the wide-band characteristics of the transducer were used to discriminate against near-surface bubble reverberation. The system is linear and can presently measure surface wave frequencies below 4.5 kHz. Waveheights as small as 0.05 in. were measured in a model tank by comparing the echo-sounder results with results obtained from a micrometer. An experiment, conducted in the Thames River, compared the performance of the echo sounder to a 15-ft resistive wave staff. Comparisons of ensemble-averaged power spectral densities obtained from the wave staff and the transducer, positioned 10 ft below the surface, were excellent for wave frequencies below 4.0 Hz.
Deep-Scattering-Layer Observations off New Zealand
Authors: Batzler W. E.
Published: October 2005

Acoustic volume scattering measurements made during the 1971 winter season at 18 deep-water stations north and east of Auckland, New Zealand, are presented in terms of volume scattering strength and column strength. (Columns extend from near surface to a depth of 1000 yds.) Both pulse-type data, at 5.0 and 12 kHz, and explosive-source data were obtained. At a given frequency, there is little station-to-station change in column strength over the 12-oct bands from 1 to 20 kHz. Typically, column strength rises sharply from 1 kHz to a maximum at 5 or 6 khz followed by a slight droop and another maximum at 16 kHz. Values fall in the range −40 to −70 dB. With one exception, night column strengths are higher than day values; this day-to-night difference has a maximum in the neighborhood of 3 kHz. The pulse results, expressed as volume scattering strength versus depth, also show station-to-station similarities; the principal scattering layers occur at about the same depths, and column strengths do not differ greatly. The distribution of volume scattering strengths with depth reveals distinguishing station-to-station differences not provided by the explosive data. Column strengths obtained from pulse data are in satisfactory agreement with those obtained from explosive measurements. Comparisons show that scattering levels off New Zealand are as high or higher than those observed in other North and South Pacific areas.
Long-Term Ambient Noise Measurements in the N.E. Pacific Ocean
Authors: Scrimger J. A.
Published: October 2005

Long-term (one-year) open ocean measurements of ambient acoustic noise were made in the N.E. Pacific Ocean using instrument packages placed on seamounts. The seamounts Cobb [summit 15 fathoms (f)], Union (summit 160 f), and Bowie (summit 16 f), extended over 612° of latitude in a near N-S direction. Packages were placed on seamounts Cobb and Bowie on terraces at about the 110-f level and on Union near the summit at about the 170-f level. Averaged 4-min samples of noise level in the 150- to 300-Hz frequency baud were obtained once per hour and recorded as a bar graph on strip paper chart. Usable data yield was about 50%. The data are presented in the form of histograms of frequency of occurrence of noise level in 5-dB intervals by months. There appears to be about a 4-dB increase in noise level in the band in the winter months. A brief description of the instrument package and the technique used for placement and recovery will be given.
Effects of Context on Voiceprint Identification
Authors: Hazen Barry
Published: October 2005

This study investigated how well the file card system of Voiceprint Identification reported by Kersta (1962) fulfills its purpose of minimizing the effects of contextually caused spectral variation, and how well it serves as either a population reduction or identification tool. Subjects received training equivalent to that received by the experimenter in the Voiceprint Identification Training Course, and achieved error rates approximating those achieved by Kersta's subjects for similar training tasks. Experimental tasks required subjects to identify unknown speakers from a population of 50 known speakers by first eliminating all known speakers they were certain were not the unknown speaker, and then attempting identification. Ten attempts were made where the unknown and known speech samples of the same speaker were excerpted from the same phonetic contexts, and 10 attempts where they were excerpted from different contexts. Statistically significant differences in subject performance for same and different context tasks indicated that the file card system does not substantially minimize the effects of contextually caused spectral variation. The magnitude of error rates suggests that it cannot be used for either population reduction or identification.
Talker Differences as They Appear in Correlation Matrices Derived from Spectra of Continuous Speech
Authors: Li K.-P. , Hughes G. W.
Published: October 2005

Previously, we have shown that stable estimates of correlation matrices derived from the outputs of bandpass filters can be obtained from about 30 sec. of continuous speech [K.-P. Li, G. W. Hughes, and A. S. House, J. Acoust. Soc. Amer. 46, 1019–1025 (1969)]. The present study describes the measurement and properties of intertalker and intratalker variability among these matrices. Three measures of the difference between two matrices were investigated, average absolute difference, Euclidian distance, and correlation between matrices. All measures of difference are consistently less for intratalker data than for intertalker comparisons. For our population of 30 talkers, the distribution of these differences shows only about 1% overlap to confound absolute identification of a given talker. The effects of processing and sample size are discussed, and applications to talker identification and normalization schemes suggested.
Some Problems in the Derivation of a Phonetic Referent for Evaluation and Lexical Representation in Automatic Recognition of Continuous Speech
Authors: Dixon N. R. , Tappert C. C.
Published: October 2005

One of the basic problems in Automatic Recognition of Continuous Speech exists relative to the representation of talker performance. Phonetically, the problem results in a requirement at the lexical level for either “narrow” transcriptions or a variety of “broad” transcriptions for representing any word. If pattern classification procedures are utilized in acoustic analysis, the former presents many problems involving inventory size. More importantly, a question arises concerning the appropriateness of the referent employed in performance evaluation. For speech, the referent—a description of what the talker actually produced rather than intended—is, even with a highly trained phonetician, many times difficult to obtain. It is clear that a single “ideal” transcription for each lexical item is inappropriate. Traditionally, in speech recognition work involving phonetic classification, a single transcription is provided for each of the words to be recognized. Systems have been proposed in which partial representation of “phonemes” may provide sufficient information for more sophisticated, i.e., context dependent, processing at a later time. However, it is not clear that these systems will be able to account for some of the dissimilatory, assimilatory, and/or ideolectical variants that a phonetician would certainly use in describing talker performance.
An Automatic Method for Computer Recognition of Continuous Speech
Authors: Purves R. Byron , Strong William J.
Published: October 2005

An automatic speech recognition system for syntactically acceptable units of continuous speech has been implemented on a digital computer. The input speech to the system is carefully spoken by a single cooperative male speaker. A primary segmentation is attempted by delineating the boundaries of fricatives, stops, and nasals. The remaining vocalic sections are subsegmented on the basis of short-time phoneme identification. The principle identification procedure uses cepstrum matching; however, auxilliary use is made of zero crossing and slope change rates for fricatives, and apparent place of articulation for stops. Three phoneme choices are assigned to each segment. In order to recognize the utterance, successive phoneme strings are generated from these choices until one is found which satisfies the lexical and syntactic constraints. The lexical constraint requires that the phoneme string consist only of “phonemicon” (phonetic dictionary) entries and the syntactic constraint requires that the word string satisfy a simplified English syntax. A relatively simple syntax checking algorithm has been devised for this purpose, which, although it admits some non-sense structures, imposes a severe constraint on allowed word strings.
Use of Syntactic Segmentation and Stressed Syllable Location in Phonemic Recognition
Authors: Lea Wayne A. , Medress Mark F. , Skinner Toby E.
Published: October 2005

Automatic speech recognition is expected to be more successful when syntactically related information is incorporated into early stages of recognition. Phonemic decisions, in particular, are expected to be more accurate and less ambiguous when contextual information is considered. A computer program has been developed for detecting boundaries between syntactic constituents from fall-rise fundamental frequency (F0) contours in connected speech. Another program detects some stressed syllables from F0 contours, intensity contours, and timing information. Resulting boundary detections and stressed syllable locations are used by a preliminary method for estimating distinctive features of some phonemes in connected speech. Vowel and consonant recognition is attempted first in the stressed syllables. Other readily detected segments, such as coronal unvoiced strident fricatives, are also found. Detected constituent boundary positions are compared with stored information about boundary positions, and are used both to choose candidate sentences independently and to help clarify phonemic results. Results for a limited sentence-recognition task are reported, and extensions to more versatile sentence recognition from syntactic segmentation, stressed-syllable location, and distinctive features estimation are suggested.
An Analysis of Wavefunction-Derived Speech Recognition Features
Authors: Pfeifer Larry L.
Published: October 2005

Based upon a wavefunction representation of wide-band filtered speech (five fixed-frequency bands), recognition features can be computed pitch synchronously and then later combined at the phoneme level. The pitch synchronous wavefunction frequency data at times acts as a formant tracker and at other times does not. The phoneme features from wavefunctions cluster much the same as equivalent formant features but not necessarily at the same locations in feature space. For certain types of sounds (e.g., /aɔ/), the detailed description provided by the wavefunction parameters can be useful in distinguishing one from the other. These and other relationships between formant and wavefunction based recognition features will be discussed.
A Model for Word-Level Conversion of Arbitrary Text to Speech
Authors: Allen J.
Published: October 2005

While the acoustic correlates of linguistic structures above the word level are of great importance in speech synthesis, it has not been possible to develop a comprehensive theory for these effects. At the single word level, however, the present model shows how any English word can be converted to 1PA symbols with stress marks sufficient to drive a phonemic synthesis-by-rule algorithm. Words are either partitioned into constituent morphemes, or processed by a large set of letter-to-sound rules. The latter rely on the lexicon to contain high-frequency exceptions, and assume that all polymorphemic words have been split up into their constituent morphs. Both monomorphemic and polymorphemic lexical stress rules are applied, and morphophonemic rules provide low-level adjustments. The complete process provides a partial model for native speakers reading aloud, as well as the means to test current linguistic phonological theories.
Plane-Wave Simulator in a Mechanically Driven Standing Wave Hydrophone Calibrator
Authors: Abbagnaro L. A. , Bauer B. B.
Published: October 2005

A method has been developed to provide plane-wave operation in the Mark III pressure gradient hydrophone calibrator [Wide Range Calibration System for Pressure Gradient Hydrophones, B. B. Bauer, L. A. Abbagnaro, and J. Schumann, J. Acoust. Soc. Amer. 51, 1717 (1972)]. Since this calibrator uses a mechanical drive rather than a transducer drive to establish the standing wave field, conventional time delay techniques could not be employed. Rather, two loudspeakers were used in conjunction with the calibrator drive to achieve a plane wave at the center of the tank. A simple operating procedure is described for using the plane-wave mode, and some experimental results are presented.
A New Underwater Microphone for Swimmer's Masks
Authors: Abbagnaro L. A. , Schumann J. , Bauer B. B.
Published: October 2005

A new underwater microphone for use with swimmer's masks was developed. This unit features an equalized fluid-filled internal structure, which renders it pressure insensitive, permitting use at all diving depths. The transducer response is controlled mechanically rather than acoustically and exhibits no change with pressure variations. The new microphone is small enough to fit into most diving mask cavities and makes use of its pressure gradient design to minimize unwanted mask speech coloration. Performance data in free-field and in a typical diving mask were obtained for this device. [Work was supported by the U. S. Navy Explosive Ordance Development Facility.]
An Electrical Load for Simulating a Transducer in an Array
Authors: Nowlin W. C. , Truchard J. J.
Published: October 2005

Individual transducer elements of large sonar arrays are subject to electrical impedance changes as a result of acoustical interactions between neighboring driven elements. In order to transmit acoustic power, the elements are driven individually or in groups by power amplifiers. When a prototype amplifier is constructed, an entire array of transducers and amplifiers may not be available for testing the amplifier. A passive electrical dummy load was constructed to have impedance characteristics equivalent to the particular type of transducer that a prototype current-source switching amplifier was to drive. An active port was added to the electrical dummy load to change the amplifier's load impedance at all frequencies of interest, thereby simulating different positions in a transducer array in which more than one element is driven. A digital computer program was written to calculate the drive voltage to be applied to the active port to obtain the desired impedance at a given frequency. The dummy load design technique is described. The dummy load impedance characteristics are compared with those of the transducer loads to be simulated; agreement is shown to be very good. [This work was sponsored by Naval Ship Systems Command.]
Designing a Reflecting Surface Array of Compliant Tubes
Authors: Brigham G. A.
Published: October 2005

A rather detailed model that considers multiple radiation coupling of compliant tube arrays has been developed and utilized for the purpose of designing several arrays. The model was generated by an iterative extension of the static solution to a uniformly loaded oval shell, and includes multiple cross-sectional bending modes as well as multiple radiation modes, although the latter restricts the model to tubes with an elliptical cross-section. No account is taken of bending in the direction of the tube's cylinder axis, since the maximum correction this introduces to the cross-sectional flexural wavenumber is a term on the order of (3HC1/SC)2 compared to unity, with H the wall thickness, C1 the shell material's longitudinal velocity, C the acoustic velocity in water, and S the cross-sectional midsurface circumference. As this factor is typically of order 5% or less, it is ignored. Numerical results for a 10-tube array are compared with experimental data for verification of the computer model. In addition several computer-evaluated array reflectivities are shown for different tube configurations. Finally, both center frequency and bandwidth are displayed as functions of array parameters. [Work performed under contract with NUSC.]
Self and Mutual Acoustic Radiation Impedances for Two Coplanar Unbaffled Disks
Authors: Van Buren A. L. , King B. J.
Published: October 2005

The self and mutual acoustic radiation impedances for two coplanar unbaffled disks are calculated using an eigenfunction expansion in terms of oblate spheroidal wave functions. Terms representing outgoing waves from both disks are included. One disk is assumed to be vibrating with a rotationally symmetrical normal velocity distribution, and the other disk is assumed to be stationary. The determination of the expansion coefficients from these boundary conditions is facilitated by the use of an addition theorem which expresses spheroidal wave functions with reference to one coordinate frame in terms of spheroidal wave functions with reference to a second coordinate frame. Numerical results for the special cases where the vibrating disk is either oscillating uniformly or vibrating uniformly on only one side are presented and discussed.
Calculations and Measurements of the Axially Symmetric Extensional Vibrations of a Circular Disk with a Concentric Hole (A Free-Flooded Ring)
Authors: Sinsky J. A.
Published: October 2005

A complete mathematical model of a free-flooded ring transducer must predict the ring's surface velocity distribution when the forces acting on the ring are known. The acoustic radiation from a radially oscillating cylindrical ring is a function of its surface velocity distribution. In particular, the farfield radiation on the axis of the ring is a sensitive function of the difference between the inside and outside radial velocities and the axially directed edge velocity. Accelerometer measurements in air were made on a number of aluminum rings of varying thickness oscillating in axially symmetric extensional vibrations, and the experimental results are compared with the two-dimensional theory of Gustafsson and Kane for high-frequency extensional vibrations of elastic isotropic plates. The results indicate that the theoretical analysis is adequate to predict the surface velocity distribution of a “thick ring.” Comparisons are also made between the theoretical analysis and “back of the envelope” approximations commonly used by transducer engineers for an elastic ring's surface velocity distribution.
Noise Reduction of a Consumer Electric Clock
Authors: Viebrock W. M. , Crocker M. J.
Published: October 2005

The noise from a consumer electric clock was studied. The clock was placed in an anechoic room for sound pressure level analysis to determine the noise sources, which were found to be impacts at the electric motor rotor bearing and impacts between gear teeth of the rotor pinion and the first reduction gear. Study of the clock case revealed that case resonances were being excited by the impacts within the mechanism with resultant noise radiation. Modifications to the case to increase damping were successful in reducing the noise associated with these resonances, although a different damper must be devised for production feasibility. Noise reductions were also obtained by modifications to the clock motor itself including reduction in magnetization of the rotor; use of softer rotors and first reduction gears; reduction in the inertia of the first reduction gear; and increase in load applied by a friction drag to the gear train. [This work was supported by Westclox Division, General Time Corporation, LaSalle, Illinois.]
Economics of New Plant Sites Based on Acoustical Considerations
Authors: Teplitzky Allan M.
Published: October 2005

Environmental noise at the property line due to an industrial operation is one element that determines the minimum site area requirements for a new plant. Residents in communities surrounding a plant hear the noise created within the plant that is attenuated by the building and the size of the buffer zone between the plant and the community. In suburban and rural areas where the ambient background noise may be low, sites for heavy industry plants become exceedingly large if insulated metal type siding is used for the building walls to achieve a satisfactory sound level at the property line. When large sites are not available, or if the price of land is high, the site area can be considerably reduced by the use of masonry or multilayered insulated metal types of siding. For a plant with an interior noise level of 90 dBA, the site area for a plant with masonry siding may be less than 10% of the site area for the same plant with insulated metal siding. The use of high sound transmission loss walls for plant buildings necessitates that noise from other sources such as fans, ventilating system, steam vents, etc., be reduced to meet the property line sound criterion. This paper presents a graphical method for estimating plant site area and setback requirements based upon maximum allowable property line noise levels, plant noise levels, and type of building siding selected for the construction. In addition, a method is proposed for determining the economic break-even point for purchasing additional property as an acoustical buffer zone versus the cost of improving the sound transmission loss of the building siding.
Evaluation of Noise Control for the World Trade Center PATH Terminal
Authors: Kessler F. M.
Published: October 2005

Track vibration isolation in the form of “tie-in-pocket” construction, a highly acoustical absorbent metal pan ceiling construction, and other noise control features were used at the newly built World Trade Center PATH Terminal Noise measurements were made at numerous positions at the Church Street PATH Terminal prior to its discontinuance as a terminal and at the World Trade Center PATH Terminal just after its completion. The results of these surveys in platform an improvement in passenger comfort due to the reduction in platform and concourse noise levels. These data were analyzed and compared as to noise criteria (NC), statistical A-weighted noise level, and statistical octave-band spectra. A noise level criterion of L10 = 75 dBA for passengers waiting at the platform was developed and compared with noise levels measured at the two terminals and at a typical midtown street location. Testing of the track lubrication system was also accomplished.
Low-Frequency Sound Radiation Characteristics of Simply Supported Plates
Authors: Moore James W. , Crocker M. J.
Published: October 2005

Sound radiation from vibrating plates is important in many engineering problems. Theories for the sound power radiated by simply supported plates have been developed by Maidanik [J. Acoust. Soc. Amer. 34, 809–826, (1962)], Smith and Lyon [NASA CR-160 (1965)], and others. In this paper, formulas have been derived which predict the sound power and farfield directivity pattern for a plate vibrating well below coincidence. It can be clearly shown that the sound power radiated is the same as for four monopoles located at the corners of the plate having equal strengths related to the plate vibration amplitude and a phase relationship depending on the type of mode excited. Similar formulas were derived for acoustic edge modes. The sound pattern for edge modes is that of two acoustic line sources. The sound power radiated by both corner and edge modes is found to depend strongly on the product of the wavenumber and the plate dimensions and on the type of mode. [Work supported by American Standard Research and Development Center, New Brunswick, New Jersey, and conducted when both authors were at the Herrick Laboratories.]
Patterns of Activity in Single Neurons of the Auditory Cortex in Unanesthetized Macaque Monkeys
Authors: Brugge J. F. , Merzenich M. M.
Published: October 2005

Action potentials were recorded from single neurons in auditory cortex on the supratemporal plane in 10 hemispheres in nine monkeys (macaca mulatta). Each monkey was trained to sit quietly in a chair with its head restrained. Pure tones were delivered monaurally or binaurally through rubber ear molds that fitted tightly into each external auditory canal. When one ear is stimulated, the number of spikes and the firing pattern depend upon the position of the stimulus within the response area of the cell. For most neurons, spike count is a nonmonotonic function of SPL. Commonly, neurons discharge a train of spikes throughout a tone of several hundred milliseconds duration at suprathreshold levels at best frequency. A few cells adapt quickly and discharge only a few spikes at onset of the tone. Others are inhibited by the tone or are excited only at the termination of the sound. When tones are delivered binaurally, the number of spikes and their temporal order are very sensitive to small interaural differences in SPL. At low frequencies, spike count is a periodic function of differences in time of arrival of the stimulus at the two ears. Neurons can have a characteristic delay. Within a given penetration, phase-sensitive neurons with very similar best frequencies and spike-count functions can have very different firing patterns.
Intensity Function for Cortical Potential Evoked by Electrical Stimulation of the VIIIth Nerve
Authors: Walloch Richard A.
Published: October 2005

The effect of intensity tipon the amplitude of the cortical potential evoked by electrical stimulation of the contralateral VIIIth nerve in an anesthetized guinea pig was studied. Square pulses, 0.5 msec in duration, were delivered through stainless-steel electrodes implanted in the VIIIth nerve. The stimulus intensity was randomly varied and the amplitude of the cortical potential was measured from a storage oscilloscope in a double blind manner. The amplitude at first rose sharply and then plateaued as the current intensity was further increased. The intensity function for electrical stimulation was different from that usually observed for acoustical stimulation in two respect. (1) For similar increases in stimulus intensity, a greater increase in the amplitude of the evoked potential was observed with electrical stimulation than with acoustical stimulation. This suggests the use of loud sound in behavioral transfer tests between acoustical and electrical stimulation of auditory centers. (2) Increases of stimulus intensity beyond that needed to produce plateau levels caused a reduction in the evoked potential amplitude with acoustical stimulation, but no reduction was observed with eleetrical stimulation. These data suggest that the reduction observed at high intensities of acoustical stimulation is due to a cochlear process, most probably the cochlear microphonic. [Supported in part by the National Institute of Neurological Diseases and Stroke and the Deafness Research Foundation.]
Effects of Frequency and Phase Reversal on Early Components of the Evoked Cortical Response
Authors: Zerlin S. , Naunton R. F.
Published: October 2005

The latency of the Na peak, a landmark of the early evoked response that occurs about 20 msec after stimulus onset, was studied with respect to (a) stimulus frequency and (b) phase reversal. Third-octave clicks (center frequencies 500, 1000, 2000, and 4000 Hz) were presented to normal-hearing listeners at sensation levels (SLs) of 5, 20, 35, and 50 dB; systematic decrease in latency was seen between 500 and 4000 Hz, approximately 2 msec at 50 SL and 5 msec at 5 SL. The effect of phase change was studied with a 250-Hz tone burst gated on at the axis crossing and off 3 cycles later; the first half-cycle of the tone burst began as either a condensation or a rarefaction (180° phase change). Results showed that the Na response to the stimulus beginning as a rarefaction occurred about 2 msec earlier than the response to the stimulus beginning as a condensation. These results may be interpreted as illustrating the close relation between cochlear events sad the early evoked cortical response.
Cerebral Asymmetry in Infants, Children, and Adults: Auditory Evoked Responses to Speech and Music Stimuli
Authors: Molfese Dennis L.
Published: October 2005

Adults process language and music sounds in different hemispheres of their brain (Kimura, 1967). This cerebral asymmetry is thought to occur during language development after 2 years of age (Lenneberg, 1967). However, recent research (Eimas, Siqueland, Jusczyk, and Vigorito, 1971) indicates that infants can categorically perceive speech sounds. It is likely that some cortical area has already specialized to process these sound. To determine if cerebral asymmetry is present, auditory evoked responses (AER) to speech syllables, words, music and speech noise were recorded from the temporoparietal language processing area Cohn, 1971) in the left hemisphere and from the corresponding area in the right hemisphere for three groups of 10 subjects—infants, children, and adults. AER waveforms were averaged and measured for amplitude changes between N2 and P2 wave components for each hemisphere. Verbal stimuli elicited greatest AER activity from the left hemisphere while the mechanical stimuli elicited the largest responses from the right hemisphere in all subjects. Furthermore, the degree of lateralization decreased with age. The results were interpreted as support for the notion that the brain is specialized to process language and music differentially from birth.
Concentration Dependence of the Visoelastic Parameters of Aqueous Glycerol
Authors: Bell C. E. , Davis C. M.
Published: October 2005

The shear and longitudinal elastic properties of glycerol-water mixtures have been investigated by means of ultrasonics [Slie et al., J. Chem. Phys. 44, 3712 (1966)]. These data were used to estimate the relaxational parameters of pure water by means of extrapolations from low temperature. The resulting 0°C data were again extrapolated as a function of concentration to pure water. In the present investigation, Brillouin scattering has been used to minimize both the temperature and concentration extrapolations. The Brillouin and ultrasonic results are found to be in significant disagreement. The effect of this disagreement on the viscoelastic parameters of pure water is discussed.
Acoustic Velocity of Fluorocarbon Liquids
Authors: Feldman H. R.
Published: October 2005

The semiempirical theories of Rao and Schaaffs, which relate the acoustic velocity in a liquid to its chemical structure, have been extended to include liquids containing fluorine atoms in the molecule. The measured acoustic velocities of nine fluorocarbon liquids were compared with the velocities predicted by the theories. The value of Rao's bond addendum [D. Sette, Ricerca Sci. 20, 102 (1950)] for the C-F bond, which minimizes the rms deviation from the measured values of acoustic velocity, is 114 cm3 (m/sec)12. Use of this value results in an rms deviation of 55.6 m/sec for the nine compounds. If one eliminates the two acids (perfluoroacetic and n-perfluorobutyric), which one would expect to be associative, the rms deviation is 38.8 m/sec for the seven remaining compounds. A single parameter fit for Schaaffs' raumerfullung C-F bond addenda [W. Schaaffs, Ergeb. exakt. Naturwiss. 25, 109 (1951)] results in an rms deviation of 46.0 m/sec, and a two-parameter fit in an rms deviation of 37.3 m/sec for the nine liquids. Further measurements of acoustic velocity have been or will be made on other fluorocarbons to obtain better values for these constants. An understanding of the acoustic properites of fluorocarbon liquids is important because their unusually low acoustic velocities make them useful as refractive media in acoustics.
Ultrasonic Wave Propagation in the Critical Temperature Region of β,β′-Dichloroethyl Ether + Hexane
Authors: Bains Elizabeth C. , Breazeale M. A.
Published: October 2005

Ultrasonic attenuation and velocity measurements in the critical temperature region of the binary system β,β′-dichloroethyl ether + hexane are presented. This system has an upper critical solution temperature at 12.7°C. Measurements were taken at frequencies between 1 and 9 MHz. The dependence of both attenuation and velocity on temperature and on frequency was investigated. The temperature dependence of the attenuation compares favorably with the theory of Fixman (J. Chem. Phys. 36, 1961 (1961); however, the frequency dependence does not. The frequency dependence of the attenuation cannot be fit by a function that is a single power of frequency. A velocity dispersion is observed in the critical region. [Research supported by the U. S. Office of Naval Research.]
Low-Frequency Ultrasonic Absorption in Triethylamine-Water Solution near its Critical Solution Temperatare
Authors: Yun S. S.
Published: October 2005

The ultrasonic absorption at low frequencies (0.3–4.5 MHz) in a triethylamine-water binary liquid solution has been measured through the critical solution temperature by means of the pulse-echo method. For each frequency investigated, the absorption coefficient exhibits a marked maximum at the critical solution temperature similar to the results shown in the earlier work at 600 kHz by A. G. Chynoweth and W. G. Schneider [J. Chem. Phys. 19, 1566 (1952)]. The temperature dependence of the attenuation α/v2 in the single phase of the solution is examined in terms of Fixman's theory and compared with the earlier results obtained for higher frequencies [S. S. Yun, J. Chem. Phys. 52, 10, 5200 (1970)]. The frequency dependence of the absorption coefficient is discussed. [This work, performed at John Carroll University, was supported by a NONR contract, NSF grant, and an Ohio University research grant.]
Vibrational Relaxational in CO2/O2 Mixtures
Authors: Bass H. E. , Shields F. Douglas
Published: October 2005

The acoustic absorption in mixtures of CO2 and O2 has been measured for 90%, 80%, and 70% concentration of O2 at 600°K and 450°K and 80% and 10% concentration of O2 at 300°K. The absorption has been analyzed to extract the rate of energy transfer between the vibration of the bending mode of CO2 and the O2 virbation and the rate at which O2 deexcites the bending mode of CO2 in a v-t process. [Work supported by the Office of Naval Research.]
Static and Dynamic PVT Measurements on B2O3 Glass Using an Acoustic Densitometer
Authors: Corsaro Robert D.
Published: October 2005

An acoustic densitometer has been used to determine the volume of a B2O3 glass sample over a wide range of temperatures and pressures, and the corresponding thermodynamic volume derivatives have been evaluated. At temperatures near the glass transition (280°C), the dynamic volume relaxation corresponding to a pressure perturbation (“pressure jump”) was also observed. Under such conditions, both the dynamic and static values of the compressibility may be evaluated, along with the apparent spectrum of relaxation times. These properties are then compared with predictions based on models of the glassy state.
Subjective Rating of Broad-Band Noises Containing Pure Tones
Authors: Goulet Pierre , Northwood T. D.
Published: October 2005

For rating the noise of broad-band sources the custom is to utilize A-weighted levels, but there is no consensus on the subjective importance of pure-tone components that may be present. This study was to provide some direct evidence on this point. Nine subjects participated, individually, and the procedure was to have the subject match pairs of noises by adjusting the level of one of them. Two experiments used a modified random noise to which a pure tone in the range 250–2000 Hz could be added. The first experiment involved a simple comparison in a quiet environment. The second involved similar noises but with the addition of a local “wanted” sound in the form of music, and the subject matched noises from the viewpoint of “intrusiveness.” A third experiment was similar to the first but utilized actual machine noises as the basic spectra. All three experiments indicated that the A-weighted level remains an adequate (slightly conservative) rating number even when pure tones are present.
The Effectiveness of Motorcycle Helmets as Hearing Protectors
Authors: Harrison R. T.
Published: October 2005

Measurements of the at-ear noise attenuation provided by several popular motorcycle helmets were made. To do this, a probe microphone was placed in a subject's ear. He then operated a motorcycle through a test cycle, which included the motorcycle's entire performance range. He then donned a motorcycle crash helmet and repeated the test cycle. In each case the at-ear noise was recorded and analyzed. A comparison of the analyses revealed the attenuation characteristics of each helmet tested. In addition to helmet manufacturer, helmet size and type of eye protection fitted were varied. Three different subjects were used to establish differences from person to person.
Effects of Continuous and Intermittent Noise on Work Behavior
Authors: Repko J. D. , Loeb M.
Published: October 2005

A synthetic-work approach was employed in an investigation of the effects of 90-dB continuous and periodic 96-dB intermittent broad-band noise on human performance. Ten Navy and Air Force ROTC cadets worked the tasks of a multiple-task performance battery (MTPB) 12 h a week (in three, 4-h sessions) during a 4-week training period. Subsequently, they were required to work 4 days, 8 h per day on a split-shift schedule during the presence of noise, and finally, work 2 additional days on the same split-shift schedule under quiet conditions. Mean percentage of baseline performance (a composite index of performance) was enhanced by a periodic 96-dB intermittent noise, and the extent of the effect varied as a function of the number of tasks concurrently performed in the work situation. On the other hand, 90-dB continuous noise neither enhanced nor degraded performance. [Research supported by the U. S. Army Behavior and Systems Research Laboratory, Army THEMIS Contract; and by U. S. Army Medical Research and Development Command.]
Measurement and Analysis of Noise from Detonating Cord Applications
Authors: Viksne A. , Logan T. H. , Easton J.
Published: October 2005

A series of tests were conducted to measure the acoustical characteristics of 10 different types of commercially available detonating cord. Test measurements were made using impulse sound level meters, recorded on tape, and analyzed for amplitude and frequency content. A number of curves are presented showing the variation in the sound pressure level with explosive core load in grains per foot, and direction of the blast wave. Covered and uncovered cord were detonated and the SPLs compared. Values obtained from these tests are compared with noise criteria for hearing damage and community response to high-intensity explosive noises. Results from sonic boom tests are used to correlate community reaction to the noise from blasting.
Language Lateralization in a Case of Extreme Psychosocial Deprivation
Authors: Krashen Stephen , Fromkin Victoria , Curtiss Susan , Rigler David , Spitz Sarah
Published: October 2005

Verbal and nonverbal dichotic listening tests were conducted on “Genie,” a 15-year-old right-handed girl, who endured 10 years of extreme isolation from age 3 to 13. When Genie was first admitted to the hospital there was little evidence of her having acquired any language. Her nonverbal dichotic results are not unusual; environmental sound perception appears to be normally lateralized to the right hemisphere. Her verbal dichotic listening results are singular in both direction and degree; she shows a left ear (right hemisphere) superiority to a degree matched only in split-brain and hemispherectomized subjects. This suggests that ear competition is taking place only between left ear contralateral and right ear ipsilateral pathways. These results are discussed in view of her steady but modest progress in language acquisition.
Memory for Dichotic Pairs: Disruption of Ear Report Performance by the Speech-Nonspeech Distinction
Authors: Day Ruth S. , Bartlett James C. , Cutting James E.
Published: October 2005

When dichotic pairs are presented in rapid succession, the best strategy is usually to segregate the items by ear of arrival. If the stimuli fall into distinguishable classes such as letters and digits, then report by class is roughly comparable to that obtained by the ear method. In the present experiment, a stimulus class distinction markedly interfered with listeners' ability to use the ear report method. The classes were speech (/ba, da, ga/) and nonspeech (500-, 700-, and 1000-Hz tones). A trial consisted of three successive pairs of speech to one ear and nonspeech to the other. In separate blocks of trials, subjects reported the order of arrival for a given stimulus class (speech or nonspeech) or for a given ear (left or right). Performance was excellent for both types of report as long as all the speech went to one ear and all the nonspeech went to the other ear. However, when speech and nonspeech switched between the ears during a trial, class report remained excellent but ear report dropped substantially. The status of stimuli as speech or nonspeech, then, is a fundamental distinction, one that can reduce the effectiveness of the normally useful ear report method in dichotic memory tests.
Perception and Production of Stops in Bilinguals and Unilinguals
Authors: Caramazza Alfonso , Yeni-Komshian Grace , Zurif Edgar , Carbone Ettore
Published: October 2005

Cross-language studies have shown that voice onset time (VOT) is a sufficient acoustic cue to separate initial stop consonants into phonemic categories. The present study is an attempt to investigate further the efficacy of VOT as a linguistic cue by examining the perception and production of stop consonants in three groups of subjects: unilingual Quebec French, unilingual Quebec English, and bilingual French-English speakers. Perception was studied through a labeling procedure using synthetically produced stop+vowel syllables. Production was assessed through spectrographic measurements of VOT in word-initial stops. The six stop consonants of each language were investigated. The two groups of unilingual subjects had different perceptual functions and the bilinguals' responses were in an intermediate position. The production data indicate that VOT can separate between the English phonemic categories of /p,t,k/ and /b,d,g/, but this measure was not adequate for the Quebec French stop categories. In addition, the data show that language switching in bilinguals is well controlled at the production level but poorly controlled at the perception level. [Research supported in part by National Research Council of Canada and PHS research grant from NINDS.]
Phonation and Loudness
Authors: Bernstein Jared
Published: October 2005

Often when vowel loudness is measured, only SPL, duration, fundamental frequency, and formant frequencies are considered as causes of loudness. In the present study, differences in loudness were measured which apparently are a function of the mode of laryngeal vibration. Stimuli were constructed by having speakers produce a series of vowels at a single fundamental frequency and at several sound pressure levels (SPLs). The sustained vowel sounds were then electronically equalized for SPL and presented to subjects as pairs of isolated vowels. Differences in loudness were reported by subjects when asked to make paired comparisons. Vowels with equal duration, SPL, formant frequencies, and fundamental frequency were judged to be different in loudness as a function of the phonation quality associated with the vowels' position in the voice range of the speakers.