bluuebunny/crossref_metadata_2025 huggingface dataset:
Discriminability, response bias, and phoneme categories in speech discrimination: II. Place of articulation
Authors: Wood Charles C.
Published: October 2005

The term “phoneme boundary effect” refers to the observation that synthetic speech stimuli which lie across a boundary between phoneme categories are discriminated more accurately than comparable stimulus differences which lie within a phoneme category. At the last meeting of the Society [C. C. Wood, J. Acoust. Soc. Am. 58, S58(A) (1975)], I described experiments which investigated the voiced-voiceless boundary effect in discrimination of differences in voice onset time (VOT). The present experiments investigated discrimination of stop consonants differing in place of articulation as cued by differences in the direction and extent of second and third formant transitions. The principal results were directly comparable to those of the VOT experiments: (a) there were both clear increases in discriminability and marked changes in response bias near the [b]-[d] and [d]-[g] boundaries and (b) increases in discriminability at the phoneme boundaries were also obtained when the formant transitions were removed from syllable context and presented in isolation. Unlike the VOT results, however, the increases in discriminability for isolated formant transitions were smaller than for the full-syllable stimuli and were also influenced by presentation order of the discrimination tasks. These latter results suggest that subjects' biases and expectancies regarding the synthetic stimuli may influence their discrimination of “isolated” phonetic cues. This possibility is currently being investigated.
Optimum phase shading of variable-beamwidth sonar transmitting arrays
Authors: Wang H. S. C.
Published: October 2005

To meet the requirement of transmitting acoustical power with variable beamwidth from certain sea-borne weapons, an array pattern synthesis method via phase shading was developed. The method is based on considerations of power radiated by the array into special regions of sea space and can be viewed as an extension of the author's earlier work [H. S. C. Wang, J. Acoust. Soc. Am. 57, 1076 (1975)] to include phase shading angles as independent array variables. To synthesize a specified or desired radiation pattern, object functions which are suitable linear combinations of acoustical power radiated into various regions of the sea were formulated. Method of steepest ascent was then used to search for a set of phase shading angles which gives a maximum value of an object function. The shading so obtained is considered to be optimum in the sense that the main beam power is always a maximum subject to the constraints on sidelobe level, main beam ripples, etc. As an illustrative example, a radiation pattern of 50° beamwidth is synthesized for an equally spaced 8-element linear array of half wavelength spacings. The reduction of on-axis main beam power is only 3.6 dB as compared with that of an unshaded array of the same excitation level.
Measurement of high-frequency underwater acoustical signals using a computer-based system
Authors: Kodosky J. L. , Nowlin W. C. , Truchard J. J.
Published: October 2005

A general purpose underwater acoustical measurement system may use analog-to-digital converter systems that have insufficient speed to meet the Nyquist sampling requirement at high signal frequencies and still provide accurate results. Acoustic test facilities are usually designed to operate over a wide range of frequencies so that at high frequencies the dimensions of the test facility are many wavelengths. Consequently, a special technique similar to that used in a sampling oscilloscope can be used to make a measurement. Some simple examples for the application of this technique are discussed. The requirements for measurement to a given accuracy are determined for various signal-to-noise ratios.
Long term castor-oil absorption by MIL-C-6183A Corprene
Authors: Fife M. E.
Published: October 2005

The long-term degradation of Corprene-backed hydrophones has been investigated by the use of color microphotography using finegrain film with slide-projected magnifications up to 500 × life size. Oil absorption is significant and visually obvious when compared to pure cork and non-oil-soaked Corprene. Variations in cork to neoprene ratio and grain of various samples of the same military specifications are visually apparent and their effect on oil absorption is discussed.
Technique for signal generation and electronic beamsteering of a parametric array
Authors: Stowe D. W.
Published: October 2005

A unique technique for generating the drive waveform and for electronically steering the beam of a parametric array has been demonstrated in recent in-water tests. The signal-generation technique involves pulse-width modulation of a 21-kHz square-wave carrier to produce the two primary frequencies required to drive the array. The difference frequency generated by the sonar (nominally 5 kHz) can be tuned to a particular frequency or can be readily chirped. Electronic beamsteering in two dimensions was achieved by providing a variable time delay for each element of a 2-dimensional 61-element array. The variable delay was achieved by varying the rate at which the modulated carrier was clocked through a matrix of shift registers. The nonlinear beam can be steered to a particular angle or scanned by linear variation of the clock frequency. In-water tests at the NUSC Millstone Research Facility confirmed the proper operation of the signal generator and beamsteering electronics and demonstrated beamsteering. [Work supported under Navy Contract N00017-72-C-4401.]
Experimental data for a rectangular parametric array
Authors: Bennett M. B. , Dittman C. W.
Published: October 2005

Experimental beam patterns and propagation data were obtained for a rectangular transducer array which was operated parametrically. The transducer was designed to produce a beam which was relatively broad in one plane and narrow in the other. The primary beams were approximately 3° × 22°, and from the data obtained, it was found that the difference-frequency beam in the broad plane could be predicted by the product of the two primary beams in that plane. The first minor lobes for each primary beam in the broad plane were also relatively broad, and thus, bonafide sidelobes at a level of −27 dB relative to the major lobe were exhibited by the difference-frequency beam. The propagation characteristics were typical of those of a parametric array. [This work was supported by Naval Sea Systems Command.]
Penetration into a sand sediment of difference-frequency sound generated by a parametric array
Authors: Jarzynski J. , Flax L.
Published: October 2005

A theoretical investigation was made of the sound field in a sand sediment, due to a parametric array located in the overlying water. The following approximations were used. First, the array was represented by a line distribution of end-fired virtual sources. Secondly, the ray method was used to calculate the sound field in the sand from each source. Attenuation in the sand was treated as a perturbation. That is, the ray paths were found for an equivalent lossless medium, while the fields along these paths were obtained using the measured attenuation coefficient of the sand. The sound field of the array was then calculated by summing the contributions from the line distribution of virtual sources extending from the projector to the sand surface. Calculations were made for an array grazing angle of 15° and difference frequencies of 5, 10, and 20 kHz. The results are compared with the experimental data of Thompson and Muir [Proceedings of the 1973 Symposium on Finite-Amplitude Wave Effects in Fluids, edited by L. Bjomo (1974), p. 119.]
Velocity of sound in superheated water
Authors: Trinh Eugene , Apfel Robert
Published: October 2005

We present the first measurements of the sound velocity of distilled water superheated to 150°C at atmospheric pressure. This was accomplished by using a prepressurization scheme [E. Harvey et al., J. Cell. Comp. Physiol. 24, 1 (1944); 24, 23 (1944)]. This procedure eliminates the microscopic gas prockets which ordinarily prevent a liquid from undergoing significant superheating. A modified all quartz spectrophotometer cell holds the liquid in which an acoustic standing wave of 2.5 MHz has been established. An optical schlieren method has been used to visualize this standing wave, thus allowing an absolute measurement of the acoustic wavelength and thereby the calculation of the sound speed. The error in the data obtained so far is estimated to be less than 0.2%. At the present time we are trying to gather additional data at higher temperatures, to refine the thermal control system, and to reduce the error. [This work supported by U. S. Office of Naval Research.]
Measurement of acoustoelastic and third-order elastic constants of rail steel
Authors: Egle D. M. , Bray D. E.
Published: October 2005

Measurements of the stress-induced changes in ultrasonic wave speeds in several samples of steels typically used in railroad rails are presented. All of the five possible relative changes in wave speeds for an initially isotropic material subjected to a uniaxial state of stress have been determined and agree to within the limits of accuracy of the measurement with the second-order theory of Hughes and Kelly. The third-order elastic constants are calculated from the acoustoelastic data.
Acoustic transmission and scattering of a plate with an impedance discontinuity
Authors: Stepanishen P. R.
Published: October 2005

The effect of a line impedance discontinuity on the acoustic transmission and scattering of a plate is investigated using the Timoshenko Mindlin plate theory. In addition to the transmitted and specular reflected planar waves which are generated by an acoustic plane wave impinging on a fluid loaded plate, the introduction of a line discontinuity results in a cylindrical wave which originates at the discontinuity. At small frequency-plate products, the cylindrical wave exhibits dipole and quadrapole directivity characteristics which are directly related to the translational and rotational impedance of the discontinuity. At large frequency-plate thickness products, the cylindrical wave exhibits highly directional acoustic coincidence characteristics which are related to the transmission coefficient of the plate. Numerical results are presented to illustrate the effects of plate damping, the frequency-plate-thickness product, and the angle of incidence of the excitation on the cylindrical wave.
Toward understanding violin plate tuning
Authors: McIntyre M. E. , Woodhouse J.
Published: October 2005

As Hutchins has shown, violin makers observe a surprising sensitivity, to small plate-thickness perturbations, of the internal damping of vibration modes of violin plates. Progress towards a systematic theory of this phenomenon is reported. The method used provides a simple framework for describing the effect on internal damping of mode shape, boundary conditions, and geometry for a wide class of materials. One important fact to emerge is that more material parameters may enter than have traditionally been measured, and indeed the usual measurement technique employing thin strips is seen to be incapable of measuring them. A more suitable technique using flat plates is described and illustrated with some computations and preliminary experimental results. These confirm the prediction that “plate-tuning effects” similar to those found in wooden violin plates can also occur in isotropic plates, for frequencies well below the level where shear motion needs to be taken into account. [We thank the Science Research Council for financial support and the Cambridge University Engineering Department for providing experimental facilities.]
On the timbre of the pizzicato violin
Authors: Shonle John I.
Published: October 2005

Several factors contribute to the timbre of the violin played pizzicato. The obvious one is the transient envelope. However, the spectrum also has some distinctive features. There is an appreciable amount of nonharmonic sound present, especially for the higher tones, which may be identified with the air and wood resonances. The number of harmonic partials which are appreciable is quite limited as compared to the bowed tone, with the higher tones having fewer partials. Specific examples of spectra will be presented.
Technique for measurement of material damping
Authors: Heine J. C.
Published: October 2005

A damping test designed to provide damping data for engineering alloys in a stress range between 100 and 50 000 psi, in a frequency range between 20 and 1200 Hz and in a temperature range between −100° and 650°F is described. Techniques employed to minimize extraneous or parasitic energy losses are discussed. Test results are displayed for typical materials with very low and very high internal damping. The procedure for estimating the specific damping capacity of an alloy from the loss factor determined for a test specimen is outlined.
Vibration-damping treatments: A manufacturer's view of past trends and future needs for products and test methods
Authors: Brown Steven M.
Published: October 2005

The state of the art with respect to vibration damping and vibration-damping testing is discussed from the point of view of the manufacturer of vibration-damping treatments. Past product types and test methods are considered. General avenues for future product requirements and future tests are indicated.
Method for evaluating the loss factor of damping materials and simple structures
Authors: Schloss F.
Published: October 2005

A direct evaluation of the loss factor of damping materials and simple structures may be made continuously as a function of frequency by measuring the phase angle of a transfer impedance, i.e., the phase angle between the force at a blocked end and the motion at the driven end. The accuracy is greatest with large damping, thereby supplementing other methods. Measurements are presented for several materials and structures over the frequency range 10–1000 Hz.
Measurement and control of internal damping in polymers
Authors: Massa D. J.
Published: October 2005

The measurement of modulus and internal damping in polymers by dynamic mechanical methods is reviewed, with emphasis on the determination of dynamic tensile and shear moduli and losses from 0.5–110 Hz, using the Rheovibron and torsion pendulum methods. Relationships between polymer structure and internal damping are illustrated for selected vinyl polymers and for aromatic polycarbonates and polyesters. Application of information concerning the frequency and temperature dependence of primary and secondary relaxation processes to the design of polymers having useful mechanical and internal damping properties is discussed.
Influence of geometry and mode shape on the internal damping of vibration modes
Authors: McIntyre M. E. , Woodhouse J.
Published: October 2005

Internal damping of vibration modes of plates and shells can depend on mode shape, boundary conditions, and geometry. A systematic theoretical investigation based on linear viscoelastic theory and Rayleigh's variational principle shows that in an isotropic material these effects stem from a complex Poisson's ratio analogous to the familiar complex Young's modulus, while for anisotropic materials they are influenced by other constants similarly becoming complex. The imaginary parts of these constants can not all be measured by the usual method of analyzing bar modes: measurements must be made on plates. A method is described and is illustrated by numerical and preliminary experimental results. Some effects of the kind described have been shown to be of great importance in the construction of musical instruments of the violin family, and they deserve attention in any situation where Q's of vibration modes are required to be accurately known. [We thank the Science Research Council for financial support and the Cambridge University Engineering Department for experimental facilities.]
Social and psychological impact of transportation noise
Authors: Singer Jerome E.
Published: October 2005

The most common form of noise in our modern American society is produced by transportation. The direct effects of this noise—otological damage, temporary threshold shifts, speech interference, etc.—have been intensively studied and are relatively well documented. In contradistinction, the social and psychological effects of this noise are indirect and not easily identified or measured, and hence, have not been the subject of many investigations. Those studies which have been done must be interpreted in the light of the context of the noise and the pervasiveness of human adaptation. They can be classified into studies of aftereffects, of social effects, of learning effects, and of quality of life. While none of these effects seems particularly severe in itself, the number of people potentially affected is so large that in the aggregate these nonspecific effects may have more impact than the direct effects induced by transportation noise.
Fundamental frequency and perceived vowel duration
Authors: Pisoni D. B.
Published: October 2005

What is the relationship between variations in fundamental frequency and perceived duration? At the last meeting of the Society, Prof. Lehiste presented some data dealing with this question. Basically, she found that when listeners are asked to judge the duration of pairs of vowels of equal duration they typically judge the first member of the pair as longer than the second. However, when the second member of the pair contained some variation in FO, listeners perceived it as longer than the first stimulus. In this paper we present the results of two experiments that bear on the general questions raised by Prof. Lehiste's findings. Subjects were presented with all possible pairs of synthetic vowels which varied in duration (160, 200, 240 msec) and fundamental frequency (falling: 200–90 Hz; level: 145 Hz; or rising: 90–200 Hz). They were asked to judge which vowel was longer. The results showed that, in general, vowels containing either a rise or a fall in fundamental frequency were perceived as longer than the corresponding vowels with level fundamentals. These findings were true regardless of the order of presentation of the pair of vowels. The results will be discussed in terms of the interaction between segmental and suprasegmental cues in speech perception. [Research supported by NINCDS Grants NS-12179-01 and NS-07040-01.]
Central masking for subjects with lesions involving the auditory temporal cortex
Authors: Calder H. B. , Noffsinger D.
Published: October 2005

Unmasked and centrally masked thresholds were measured for normal listeners and for listeners with unilateral lesions involving the auditory temporal cortex. The signal was a 1000-Hz pure tone with duration of 20 or 100 msec. The masker was a 60-dB SPL, 1000-Hz pure tone and was either continuous or gated with a 200-reset duration. Signal and masker were presented to different ears. Both signal and masker were presented via hearing aid receivers to maximize interaural attenuation. In the gated masker condition, delay between masker and signal onset ranged from 20 to 150 msec. Data from the normal listeners agreed well with those from previous studies. Masked thresholds for the cortical-lesioned subjects were much higher than for the normal listeners. Generally, maximum threshold shift was observed when the masker was presented to the ear ipsilateral to the lesioned hemisphere. When the masker was presented contralateral to the lesioned hemisphere, performance was normal. One of the cortical-lesioned subjects had greater than normal threshold shifts for both ears. As signal onset delay increased, masker effectiveness decreased for all subjects.
Context-independent properties for place of articulation in stop consonants
Authors: Stevens Kenneth N. , Blumstein Sheila E.
Published: October 2005

Previous studies investigating the role of bursts and formant transitions as cues for stop consonants have emphasized the lack of acoustic invariance for a given place of articulation in different vowel contexts. A series of perception experiments was conducted to determine whether there are more general properties of the acoustic signal that uniquely specify a particular place of articulation. In the first series, several synthetic continua representing the phonetic dimensions [ba da ga], [bi di gi], and [bu du gu] were presented to listeners for identification. These continua consisted of stimuli in which (a) only the direction and extent of the F2 and F3 transitions varied and (b) both the spectrum of an initial burst and the direction and extent of F2 and F3 varied. In a second series of experiments, [di gi] and [bu du gu] stimuli with various combinations of bursts and transitions were identified and rated by listeners. Results indicated that the phonetic dimensions [b], [d], and [g] exhibit general acoustic properties independent of the particular vowel context. These properties can be defined in terms of location and diffuseness of spectral energy at stimulus onset. [Work supported by NINCDS.]
Perceptual study on nasality using synthetic sounds
Authors: Kasuya H. , Takeuchi S. , Kido K.
Published: October 2005

The acoustic correlates of nasality have been investigated from a perceptual point of view. An active model for specifying nasality obtained on the basis of perceptual experiments showed quite reasonable results for nasal murmurs but not necessarily for nasalized vowels [S. Takeuchi et al., preprints of the SCS-74, Vol. 3, pp. 141–148]. For improving the model, more detailed experiments were performed with speech sounds synthesized by adding a pole-zero pair or a pole only to the non-nasalized vowel spectra. By taking the contributions of the frequency locations of such a pole-zero pair or pole to the perception of nasality into account, the nasalized vowels were fairly well specified by our model.
Speech rate influences on the perception of stop voicing
Authors: Summerfield Quentin
Published: October 2005

Measures from speakers of British English show that voice-onset times (VOT's) produced in prestressed, prevocalic stop-consonants decrease as speech rate increases. Complementary adjustments occur in perception: if the syllabic rate of a synthetic precursor phrase which introduces test syllables drawn from a CV VOT continuum is increased, phoneme boundaries shift to shorter VOT's. The perceptual effect (a) is dependent upon timing variations in at most the 750 msec of the precursor immediately preceding the test syllable; (b) is almost unaffected by a mismatch of vocal tract length between precursor and test syllable; and (c) is substantially diminished if the silent closure interval between precursor and test syllable is longer than about 100 msec. These results suggest that the effect is not subsumed by the perceptual extraction and application of a speaker-dependent, speech-rate parameter but depends upon immediate computations of timing relations over short stretches of perceptually continuous running speech. Further experimentation is required to specify how perceptual measures of the durations of the vowels, the closure interval and the VOT, in VCV contexts, interact and so to determine the status of these variables as cues and/or contexts for the perception of stop voicing in running speech. [Work supported by J.S.R.U. at The Queen's University of Belfast, U.K.]
Static and dynamic acoustic cues in distinctive tones
Authors: Abramson Arthur S.
Published: October 2005

It is conventional to classify phonemic tones into dynamic or contour tones and static or level tones. The perceptual relevance of this impressionistic dichotomy is considered here for Central Thai, which has two dynamic tones (falling and rising pitches) and three static tones (high, mid, and low). A fundamental-frequency range appropriate to an adult male voice was used to synthesize three series of tonal variants on a syllable type available for five tonally differentiated words: (1) sixteen f0 levels at intervals of 4 Hz, (2) sixteen f0 movements from a mid origin to end points ranging from top to bottom of the range in steps of 4 Hz, and (3) seventeen variants rising from the bottom to end points from top to bottom in steps of 4 Hz. The stimuli were played to native speakers for identification. The results indicate that level variants contain sufficient cues for identification as static tones but with considerable overlap. Identification, however, is enhanced by slow f0 movement. Rapid f0 movement is required for dynamic tones. Although imprecise, the typological dichotomy is useful.
Acoustic phase variation and prediction of moving-source parameters in an isospeed channel
Authors: Jacyna G. M. , Jacobson M. J.
Published: October 2005

The effects of arbitrary motion of a cw source and depth-dependent sound speed on the total acoustic field at a fixed receiving point are considered briefly. An application is made to a channel of uniform depth in which the source follows a short straight-line path with constant velocity. Both primary and cumulative phase of the total acoustic field are investigated as a function of receiver time for various source trajectories and phase rate is examined in terms of an arbitrary, but fixed, receiver frequency. For large source ranges, approximate cumulative phase can be expressed as a hyperbolic function of time. The space factors of two arrays of colinear, equally spaced, omnidirectional point receivers, together with power spectra or the cross-correlation function, are employed to illustrate one method for determining source speed, location, and bearing. Additionally, if cw source frequency is unknown, it can be determined explicitly. [Work supported by ONR.]
Velocity dependence of multipath transmission fluctuations from a moving source
Authors: Flanagan R. P. , Clark J. G. , Weinberg N. L.
Published: October 2005

Propagation from a moving source to fixed receivers has been analyzed using coherent ray-tracing techniques. The cases studied include radial motion at velocities up to 20 kts from a shallow source to receivers below the SOFAR channel. The time rate of change of phase due to boundary interaction and travel time variation for various rays are examined. The resulting amplitude time series are compared on both normal and expanded time scales illustrating the effect of source velocity. The principal objective, however, is to study the velocity dependence of multipath interference effects and their influence upon array reception of multipath signals.
Ray diffusion in inhomogeneous sound channels
Authors: Mellen R. H. , Browning D. G. , Goodman L.
Published: October 2005

Low frequency propagation measurements in sound channels often show a frequency-independent attentuation that is evidently caused by scatter from internal inhomogeneities. Using the Garrett-Munk internal wave model [J. Geophys. Res. 80, 291–297 (1975)] as the scatter mechanism, approximate solutions for the ray-diffusion equation are obtained for typical inhomogeneous sound channels with source and receiver on the axis. The resulting attentuation coefficients are in good agreement with experiment. [Work supported by NUSC.]
Effect of internal tides on underwater sound propagation
Authors: Zarur G. L. , Graves R. D. , Nagl Anton , Überall H.
Published: October 2005

We have developed a normal-mode computer program for stratified media which, in a manner similar to methods of Pedersen and Gordon and of Stickler, approximates an arbitrary sound velocity profile by segments piecewise linear in depth and employs Airy-function solutions in each segment, or trigonometric functions for near-vertical portions of the profile. This program has been used in order to investigate effects of profile fluctuations on the propagation properties of underwater sound. In particular, we considered the changes in velocity profiles recently calculated by Mooers [J. Acoust. Soc. Am. 57, 1067 (1975)] as caused by the action of internal tides. Significant effects on the location and intensity of caustics and convergence zones have been found. [Supported by the Office of Naval Research Code 486.]
Comparison between computed and measured beam ambient noise
Authors: Marshall S. W. , Wales S. C.
Published: October 2005

Ambient noise at low frequency (20 ⩽ f ⩽ 120 Hz) has been modeled using a discrete source, Monte Carlo program (SIAM). The statistics of ambient noise levels in the beam of a horizontal array have been computed for a specific case (beamwidth = 15°) where a survey of surface ships together with measured transmission loss provided the inputs to the model. These computed results are compared to data from a horizontal array taken at the same time and at the same location as the propagation data. Results from the two methods are in quantitative agreement, indicating that this method of beam noise prediction is valid. [Work supported by ONR.]
Measurement of boundary-layer pressure fluctuations at low wave number on a rough wall
Authors: Farabee T. M. , Geib F. E.
Published: October 2005

Measurements of the spectral density of the wall-pressure fluctuations at low wave number on a rough wall are presented. The data were obtained in air with a linear array of six flush-mounted microphones whose outputs were combined in a manner that provides a direct measure of the spectral density as a function of wave number and frequency. Measurements were made at a number of flow speeds ranging from 30 ft/sec (9.1 m/sec) to 160 ft/sec (48.8 m/sec) and for frequencies up to 20 kHz. Three roughness conditions were employed, two of which were hydraulically rough. Roughness Reynold's numbers based on roughness height, friction velocity, and kinematic viscosity ranged from 20 to 1200. Comparisons are made with smooth-wall data and show that the roughness markedly affected the convective and acoustic components of the pressure field.
Electrophysiological correlates of basilar membrane motion in the turtle
Authors: Paton J. A. , Moffat A. J. M. , Capranica R. R.
Published: October 2005

We have studied the response properties of single fibers in the auditory nerve of the red-cared turtle, Pseudamys scripta elegans, as a means of inferring basilar membrane mechanics in an evolutionary forerunner of the mammalian cochlea. Responses to tone bursts and clicks were recorded with glass micropipettes from over 100 different auditory fibers in a number of animals. All of the units were simply tuned, with a single frequency to which they respond maximally (best excitatory frequency, BEF). The BEF's were uniformly distributed from 80 to 450 Hz. The most sensitive units had BEF's near 300 Hz with thresholds between 30 and 40 dB SPL. The sharpness of tuning (Q10 dB) of units increased monotonically with BEF. In response to clicks, the units discharged several times with inter-spike intervals which decrease with BEF. For all units the latency at 20 dB above threshold was shorter for condensation than for rarefaction clicks. We conclude that frequency analysis along the basilar membrane of this species is very similar to that in mammals; the primary difference is that the frequency range of the turtle is more restricted. [Work supported by NSF Grant BMS 74-20053.]
Effects of anoxia on the response properties of auditory nerve fibers in the American toad
Authors: Capranica R. R. , Moffat A. J. M.
Published: October 2005

Single-unit recordings in the eighth nerve of toads (Bufo americanus) were compared before, during, and after anoxia. The animals were made anoxic by introducing CO2 into the lungs by means of a canula inserted through the glottis. The threshold of an auditory nerve fiber increased by 10–30 dB within 2–3 min following the onset of CO2. The best excitatory frequency of the fiber remained the same. Spontaneous activity decreased and the tuning curve broadened. During anoxia, tone-on-tone inhibition persisted. Upon switching from CO2 back to an air-oxygen mixture, the response properties of a fiber returned to their initial state within 10–15 min. [Supported by NIH Grant NS-09244.]
Frequency encoding in field crickets
Authors: Paton J. A. , Capranica R. R.
Published: October 2005

We have studied the properties of auditory interneurons in field crickets as they relate to the encoding of frequency information in communication signals. Tungsten microelectrodes were used to record from single units in the neuropil of the prothoracic ganglion of the Australian field cricket, Teleogryllus oceanicus. Based on their maximal frequency sensitivity, four types of tonic, short-latency units were found: (1) 5-kHz units with ipsilateral input; (2) 5-kHz units with contralateral input; (3) broadly tuned 15-kHz units; and (4) 5-kHz units which are inhibited by frequencies below their best excitatory frequency. Thus information encoded in “labelled lines” was available at this level of the auditory system for both gross frequency discrimination between 5 and 15 kHz and fine frequency discrimination near 5kHz. The possibility also exists for latency encoding of frequencies near 5kHz due to the frequency-specific latency of the last type of interneuron listed.
Introductory remarks
Authors: Frederick Julian R. , Cook Richard K.
Published: October 2005

Acoustic emission is a relatively new area of technology that is rapidly becoming a useful method for the nondestructive testing of materials. It is defined as “a transient elastic wave generated by the rapid release of energy from a localized source within a material.” Common sources of acoustic emission are dislocation motion, twinning, and crack propagation. Some of the first quantitative measurements of acoustic emission were reported by Warren P. Mason and his colleagues in 1948, and this session is being presented in recognition of his pioneering work. The invited papers that follow review the present state of the theory and experiment in acoustic emission and describe some of its uses in engineering, one of the most promising of which is the monitoring of nuclear pressure vessels to detect crack growth.
Study of the acoustic features of word juncture using speech analysis and synthesis
Authors: Nakatani Lloyd H. , Dukes Kathleen D.
Published: October 2005

People can usually distinguish the word juncture in contrastive twins of word pairs such as play nice and plain ice. We can see many features which differ between the twins in spectrograms, but observation alone cannot tell us which features ate important to the perception of juncture. The contributions of pitch, amplitude, timing, and segmental features to juncture perception were studied as follows. Parametric representations of twins X and Y were obtained by analyzing natural speech, and the above features were exchanged between the twins in a complete factorial design. A feature f was considered important for juncture perception if exchanging f between X and Y also caused perception to be exchanged; that is, listeners heard Y when presented with X possessing feature f of Y, and vice versa. Listeners' responses indicated that all the features were important, but the importance of any particular feature or set of features depended on the juncture consonant. Features also interacted prominently for some consonants
Tuning of isolated musical intervals
Authors: Rakowski A.
Published: October 2005

Systematic deviations from the equally tempered values were observed while tuning the frequency of a pure tone up and down against the standard frequency, to tune up 12 musical intervals within an octave in randomly selected order. The standard frequencies were 125, 250, 500, and 1000 Hz. Four trained music students served as subjects and the total number of observations per point was not less than 80. It has been shown that small intervals are tuned smaller and large intervals larger than it could be predicted from the equally tempered scale. The observed octave enlargement effect is in agreement with the previously published data.
Experiments to assess musical instrument quality
Authors: Bowsher J. M.
Published: October 2005

Work in progress, supported by the Science Research Council, on the transient behavior of trombones and its possible relation to quality is described. The approach is along three paths: (a) a measurement of the input impedance firstly in the steady state and then in the transient state; (b) a study of the basic fluid dynamics of the system to examine the significance of the effects of microturbulence, boundary-layer fluctuations, etc. on the starting transient; (c) a psychological study of the decision processes employed by players and listeners and the subjective magnitudes involved when assessing instrument quality. Although only very preliminary indications are to hand, approach (c) is beginning to seem the most useful and data obtained in respect of other instruments also indicate that nonacoustical factors may be paramount in determining the overall judgment of the musical quality of an instrument. For example, according to our first investigations, the most important attribute of a trombone seems to be the mechanical behavior of the slide.
Wind instrument final adjustment procedures
Authors: Benade A. H.
Published: October 2005

Many aspects of the “goodness” of wind instruments are perceptual correlates of strong cooperation between several air-column modes in the production of each note in the scale. Laboratory resonance and spectrum measurements are immensely useful in showing the basic properties of an instrument, but its final adjustment should be made under playing conditions using auditory cues. Accurate mapping of intermode relationships is possible using listening experiments based on the dependence of intermode coupling on playing level, effects of bore perturbations on the lower-mode frequencies, changes in the upper-mode frequencies by shading of tone holes or bell, changes associated with the use of register holes and unconventional fingerings, and also the changes arising from control of mouthpiece, reed, and embouchure. Once the properties of the played instrument are mapped, adjustment procedures can be worked out and applied under the guidance of further playing experiments in order to improve performance in a manner consistent with other musical requirements such as tuning. Practical illustrations will be presented for all woodwind and brass instrument types.
Redevelopment of an eighteenth-century oboe reed
Authors: Hadden W. James , Vas Dias Harry A.
Published: October 2005

The design of reeds to be used with modern reproductions of early eighteenth-century oboes is discussed. As a starting point, an extensive pictorial-historical search was conducted which revealed striking differences from present-day reed shapes. The search for the optimal reed design has been aided by elementary acoustical analyses, and tested by the usual criteria of trueness of scale and ease of sound production. The current best approximation will be demonstrated, as will be other interesting failures.
Discrimination of speech-sound categories by the chinchilla: A progress report on syllable-initial voiced-plosive consonants
Authors: Miller James D. , Kuhl Patricia K.
Published: October 2005

Chinchillas are being trained to discriminate between pairs of four categories of syllables: bV, dV, gV, and V. Within each category, irrelevant variations are introduced in sound levels, talkers (6 male and 6 female), and vowels (/i, I, ɛ, æ, a, ɔ, u, ʌ/). Preliminary results indicate that while all of these tasks are difficult for the chinchilla, CV vs V and bV vs dV appears to be the easiest, bV vs gV intermediate, and dV vs gV appears to be nearly impossible. The definite, but limited, success of the chinchilla in discriminating these speech-sound categories is interpreted in terms of the chinchilla's poor resolution of spectral differences along the cochlear partition when compared to man. [Supported by NIH Grant NS 03856 to CID.]
Face-to-face communication in noise
Authors: Waltzman Susan B. , Levitt Harry
Published: October 2005

An experiment was performed to check the validity of the distance vs speech-interference level curves for face-to-face communication in noise. Monosyllabic word intelligibility was measured both with and without visual cues at talker-to-talker distances of 2, 4, and 8 ft, and at speech-interference levels of 65, 75, and 85 dB. The curves were found to be reasonably consistent with the data when no visual cues were available, but underestimated tolerable speech-interference levels for barely reliable communication with visual cues. Another major source of error was the difference between the observed rate of attenuation with distance of the speech signal and the idealized free-field rate of attenuation assumed for these curves. Errors resulting from this assumption were found to be consequential only at the larger talker-to-listener distances. Other important factors which affected the accuracy of the curves were the total speech power of the talker, the shape of the speech power spectrum, and the rate at which the talker raises his/her voice in noise.
Some features of perceptual errors
Authors: Goldstein Louis , Browman C. P.
Published: October 2005

Two questions about the relationship between phonetic features and perceptual errors are explored: (1) When we mishear an utterance, what features are most likely to be in error? (2) Is there a hierarchy of feature values with respect to the likelihood of a given phoneme being incorrectly perceived; i.e., are phonemes with one value on a given feature more or less likely to be misheard than phonemes with another value on this same feature? Questions are answered with respect to a previously reported experiment [L. Goldstein, J. Acoust. Soc. Am. 58, S58(A) (1975)], in which subjects heard one-, two-, and three-syllable meaningful speech segments cut out of context and reported what they heard. Results are relevant to constructing a hierarchy of acoustic information, in terms of the importance of this information for a listener making higher-level decisions about what word or phrase has been perceived. [Work supported by NIH.]
Remote acoustical sensing of ocean parameters
Authors: Munk Walter H. , Worcester Peter F.
Published: October 2005

We have conducted some measurements preliminary to the possible establishment of an environmental acoustic array off California. Some simultaneous two-way transmissions with sources and receivers at approximately 1 km depth and separated by 25 km will be discussed. For this geometry there exist essentially an upward path and a downward path; each has only a single turning point. At frequencies below a cycle per day we hope to use the array in a deterministic mode to study the drift of mesoscale eddies and intrusive features. At higher frequencies we expect to obtain information about the statistical properties of internal waves. Some preliminary results will be given.
Acoustic sensing of ocean processes
Authors: Jobst W. , Clark J.
Published: October 2005

It is shown that acoustic ray paths between a fixed source and fixed receiver act as continuous lines of environmental sensors. For an axial ray, the phase response is identical to that of an unshaded line array steered perpendicular to the direction of acoustic transmission. The axial-ray response to the internal-wave continuum and to internal tides are calculated, and it is shown how acoustics can be used to map ocean processes. The phase response for nonaxial rays is estimated using a ray trace program with the speed of sound variable as a function of range and time.
Acoustic phase processing for sensing ocean parameters
Authors: Adams S. L. , Jobst W. J.
Published: October 2005

The received phase of a transmitted acoustic continuous wave (cw) signal has been shown to provide a measure of ocean parameters along the propagation path. This paper contains a review of the problems encountered in measuring phase and considerations for designing a phase estimation algorithm. The algorithm must consider the characteristics of the phase process, the noise, and especially the problem of multipath fades. Spectral analysis of the phase process must be done with care because of the large fraction of energy concentrated at the low (semidiurnal and below) frequencies. An analysis of quantization error in the measurement of phase and estimation of the phase spectrum is presented. [Work supported by ONR, Code 222.]
Backscatter measurements using side-looking sonar
Authors: Lowenstein C. D.
Published: October 2005

Signals from a 110-kHz side-looking sonar have been digitally processed in real time to remove the variations due to small-scale vehicle motions and transducer beam pattern. The residual signals can be used to measure the backscattering coefficient of the ocean bottom at grazing angles from 45° down to 6°. The system is calibrated by use of a cross-frequency reference transponder. Data have been gathered in several areas of the Eastern Pacific and in the North Atlantic. [Work supported by U.S. Navy.]
Acoustic microstreaming as initiator of intravascular mural thrombi in vivo
Authors: Williams A. R.
Published: October 2005

Acoustic microstreaming (i.e., rapidly rotating small-scale fluid motion) was developed inside intact blood vessels in vivo when a discrete portion of the vessel wall was driven to oscillate at an ultrasonic frequency. Young adult male mice were anaesthetised by the intraperitoneal administration of Nembutal and portions of the exposed femoral artery or vein were coupled to the hemispherical tip of a 115-mm-radius steel wire oscillating in its transverse mode at 20-kHz. Alternatively, the 52.5-μm-diameter tip of an exponentially tapered, steel velocity transformer oscillating in its longitudinal mode at 85.6 kHz was coupled to the outside of a terminal branch of the mouse's mesenteric circulation (vessel diameters about 40 to 100 μm). The irradiated femoral vessels were examined using a variety of histological techniques while the transparent mesenteric vessels were viewed directly through a microscope during the ultrasonic exposure (a 16-mm microcinematographic film will be shown). Both techniques have provided complementary information for a variety of amplitude dependent thrombogenic effects of acoustic microstreaming in vivo. These include the formation of platelet thrombi which may adhere to the vessel wall or embolise downstream and the induction of widespread blood coagulation which may seal the vessel. Thus, the intravascular presence of a generator of high-amplitude acoustic microstreaming (e.g., any of the various forms of ultrasonic cavitation which might occur in vivo) could, under certain circumstances, constitute a significant thrombogenic health hazard both at the site of irradiation and downstream from that site.
Theoretical thresholds for small-scale bioeffects from sonically produced stresses
Authors: Nyborg Wesley L.
Published: October 2005

It was shown in experiments at 20 kHz with single resonant bubbles (Rooney, 1970) and vibrating wires (Williams, Hughes, and Nyborg, 1970) that bursts of sonically produced viscous stress in the vicinity of 5000 dyn/cm2 cause membranes of RBC (red blood cells) to leak hemoglobin. For platelets and white blood cells the viscous-stress thresholds for functional change are lower by about a factor of ten. (Williams, 1974; Crowell, Kusserow and Nyborg, 1976; Brown, Lemuth, Hellums, Leverett and Affrey, 1975.) Using the above information together with approximate acoustical theory, thresholds can be estimated for cellular changes at megahertz frequencies, provided that stable gas bubbles are present, of resonance size. According to such estimates, microscale biological change can occur if a stable resonant bubble is present in blood plasma and is set into pulsation by a 1-MHz plane travelling wave with intensity of the order of 1 mW/cm2. Such an intensity is much lower than reported thresholds for bioeffects of megahertz ultrasound. Possible reasons for this will be discussed. [Supported by NIH grant GM 08209.]