bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for a general template in central optimal processing for pitch of complex tones
Authors: Gerson A. , Goldstein J. L.
Published: October 2005

Optimum prcessor theory sucessfully accounts for earlier pitch data by including the constraint that component tones in a complex stimulus are estimated as successive harmonics. This constraint gives the paradoxical prediction that a periodic complex tone comprising nonsuccessive harmonics cannot evoke periodicity pitch corresponding to its period. Most published data from pitch-shift experiments imply the necessity for this constraint. New periodicity pitch experiments on pitch shift and musical interval recognition were performed which prove that the theoretical constraint is not generally true. New and old data are reconciled by replacing the maximum likelihood estimation of the theory with maximum posterior probability estimation and removing the successive harmonic constraint. Periodicity pitch is estimated by optimizing the match between the aurally measured frequencies of stimulus components and a general harmonic template over some a priori expected pitch range. The new, more general, formulation reduces in many experimental situations to the successive harmonic constraint as a special case.
Psychophysical tuning curves measured in simultaneous and forward masking
Authors: Moore Brian C. J.
Published: October 2005

The level of a masker necessary to mask a probe fixed in frequency and level was determined as a function of masker frequency using a two-interval forced-choice technique. Both simultaneous- and forward- masking techniques were used. Parameters investigated include the level of the probe tone and the frequency of the probe tone. The general form of the psychophysical tuning curves obtained in this way is quite similar to that of single-neurone tuning curves, when low-level probe tones are used. However, the curves obtained in forward masking generally show sharper tips and steeper slopes than those found in simultaneous masking, and they are also generally sharper than neurophysiological tuning curves. For frequencies of the masker close to that of the probe a simultaneous masker was sometimes less effective than a forward masker. The results are discussed in relation to possible lateral suppression effects in simultaneous masking, and in relation to the observer’s use of pitch cues in forward masking. It is concluded that neither the simultaneous-masking curves nor the forward- masking curves are likely to give an accurate representation of human neural tuning curves.
Fundamental frequency in the speech of infants and children
Authors: Keating Patricia , Buhr Robert
Published: October 2005

Fundamental frequency ranges of six normal infants and children from 33 to 169 weeks were determined by narrow-band spectrographic analysis. Fundamental frequency values ranged from 30 to 2500 Hz, well outside the values reported in previous studies of noncry utterances. The use of fry, modal, and high registers is also discussed.
Multiphonic tones in the woodwind instruments
Authors: Backus John
Published: October 2005

The orchestral woodwind instruments have been empirically designed to give musical tones heard with a single definite pitch and a characteristic quality. However, certain unorthodox fingerings and/or embouchure adjustments can result in tones of a quite different character. They are heard as perhaps two separate pitches sounding simultaneously, or as perhaps a tone of rather indefinite pitch but of a ’’rough’’ or ’’beating’’ quality. Such tones have been named multiphonics. They were investigated as follows: The instrument was fingered and blown to produce a multiphonic tone. A microphone, supplied with an appropriate probe, picked up the internal standing wave; the microphone output was recorded on tape. Loops made from this tape allowed the internal standing wave to be reproduced continously for analysis. The input impedance curve of the instrument with the multiphonic fingering was also plotted. It was found that multiphonic tones consist of two independently generated main components, one associated with the lowest resonance of the instrument, and the other with the third and fourth resonance. Furthermore, the higher-frequency component is amplitude modulated somewhat by the low-frequency component because of the nonlinearity of the air flow through the reed aperture. This results in two more components whose frequencies are given by the difference and sum, respectively, of the two main component frequencies. Interactions of harmonics of the main components may generate other smaller higher-frequency components. Listening tests demonstrated that the ear generally can hear the two main components and the difference frequency; in some cases other components can also be heard.
Determination of volume scattering and possibly biological content from sea-bottom echo fluctuations
Authors: Nanda J. N.
Published: October 2005

The results of the observations made during the ’’Downwind’’ expedition of 1958 in the South Pacific are discussed and the average root-mean-square deviation of the volume scattering coefficient in the mid Pacific is obtained as 0.8×10−4. The coefficient would be more than three times this value if the scattering follows a standard statistical distribution. This value is of the same order as reported in literature. From the observed mean-square deviation, we first subtract the contribution, if any, from the thermal microstructure. Precautions are taken so that the variance due to the movement of the transducers of multipath transmission is negligible. The volume scattering is attributed primarily to the biological content, but has contributions also from other inhomogeneities, such as air bubbles, cavitation bubbles, and inorganic debris, indirectly related to the biological content. An estimate of a very low biological content in a particular area was confirmed by net hauls. The method is independent of the reflectivity of the sea bottom and promises to be an inexpensive tool for fishery work.
Detection of intensity differences between brief adjacent tonal stimuli
Authors: Sparks David W. , Nixon James C.
Published: October 2005

Four experiments are reported in which observers were required to detect small intensity changes between brief adjacent tonal stimuli using a 2AFC procedure. Tonal durations and interburst intervals in experiment I were covaried between 20 and 320 ms and listeners were required to detect burst pairs having a 1.5-dB intensity decrement between bursts. Detection was poorest for the shortest combinations of tone-burst and interburst interval and improved with increases in the duration of either. In experiment II, intensity was the independent variable and performance was evaluated when there was unequal energy between the two bursts contained within each observation interval. Differences in the total signal energy between observation intervals appear to have been the detection cue for the shortest tone-burst –interburst-interval combination. In experiment III, detection performance was evaluated when there was equal energy between tone bursts in each observation interval. The between tone-burst intensity difference had to be dramatically increased over experiment II for equivalent performance at the shortest burst-duration –interburst-interval combination. In experiment IV, intensity -detection performance was compared under conditions of monotic and dichotic stimulation. Dichotic performance was superior to monotic performance.
Simple pitch-dependent algorithm for high-quality speech rate changing
Authors: Neuburg Edward P.
Published: October 2005

A new time-domain method is described for speeding up or slowing down speech without changing its quality; spectral shape and pitch contours are preserved. The method is easily implementable in real time, and is effective for noisy speech. It consists of a simple pitch detector followed by an algorithm that discards (or repeats) pieces of speech equal in length to a pitch period. The method is not pitch synchronous. Rate changes from 0.5 to 2.0 sound natural; slow down to 0.1 is intelligible.
Temporal switching between binaural information sources
Authors: Pollack Irwin
Published: October 2005

An estimate of the rate of perceptual switching between two binaural information sources was sought by a procedure which employed an emergent perceptual property—the shape of the binaural sound image. Random polarity-modulated pulse trains were delivered to the two ears with controlled periods of interaural phase agreement and of phase disagreement. As the rate of alternation between the two interaural states is increased, discrimination suffers. With equal periods of phase agreement and disagreement, threshold periods of 2.2–3.4 msec, or about 300–450 alternations per second, are obtained. Such rates far exceed estimates of the rate of interaural switching obtained by other experimental paradigms. With unequal periods of agreements and disagreements, a minimum threshold period of 1.5 msec is the limiting factor. Large individual differences were noted. Other procedures for coding binary information yielded similar results. Rapid switching rate thresholds are obtained for narrow-band signals over a wide frequency range. A ’’central integration time’’ is identified with the threshold interaural switching period, and appears to be identical with the minimum integration time for monaural tasks.
Adaptation of residue pitch
Authors: Hall Joseph W. , Soderquist David R.
Published: October 2005

Residue pitch was examined by means of adaptation. The monaural perceptibility of a residue pitch was measured before and after exposure to ipsilateral or contralateral adapatation stimuli of variable spectral composition. Several aspects of adaptation were investigated: pitch channel specificity, number of stimulus components necessary to adapt a residue channel, importance of temporal and spectral factors for adaptation, and the relation between pure-tone and residue pitch. It was found that there are residue-pitch channels specifically sensitive to the spectral region and ear of presentation of the stimulus. At least two harmonics were necessary to adapt a residue channel, and pitch channels were found to be insensitive to temporal factors. Residue and pure-tone pitch seemed to be extracted by different mechanisms, haveing independent channels. The data presented augment the understanding of ptich perception and suggest refinements for pitch-perception models.
Speech perception by the chinchilla: Identification functions for synthetic VOT stimuli
Authors: Kuhl Patricia K. , Miller James D.
Published: October 2005

In an attempt to clearly differentiate perceptual effects that are attributable to ’’auditory’’ and ’’phonetic’’ levels of processing in speech perception we have undertaken a series of experiments with animal listeners. Four chinchillas (Chinchilla laniger) were trained to respond differently to the ’’endpoints’’ of a synthetic alveolar speech continuum (0 ms VOT and +80 ms VOT) and were then tested in a generalization paradigm with the VOT stimuli between these endpoints. The resulting identification functions were nearly identical to those obtained with adult English-speaking listeners. To test the generality of this agreement, the animals were then tested with synthetic stimuli that had labial and velar places of articulation. As a whole, the functions produced by the two species were very similar; the same relative locations of the phonetic boundaries, with lowest VOT boundaries for labial stimuli and highest for velar stimuli, were obtained for each animal and human subject. No significant differences between species on the absolute values of the phonetic boundaries were obtained, but chinchillas produced identification functions that were slightly, but significantly, less steep. These results are discussed with regard to theories of speech perception, the evolution of a speech-sound repertoire, and current interpretations of the human infant’s perceptual proclivities with regard to speech-sound perception.
On reducing the buzz in LPC synthesis
Authors: Sambur M. R. , Rosenberg A. E. , Rabiner L. R. , McGonegal C. A.
Published: October 2005

A method for reducing the characteristic buzz of LPC synthetic speech is presented. The method consists of the use of a nonimpulse source for exciting the LPC synthesizer during voiced sounds. One novel feature is that the temporal parameters of the source are kept in fixed proportion to the pitch period. An extensive perceptual experiment has shown that the resulting quality of the synthesis is significantly preferred over the quality of the standard LPC synthesis.
Ultrasonic velocity and attenuation in mammalian tissues
Authors: Chivers R. C. , Parry R. J.
Published: October 2005

A compilation, from the original papers, is presented of the data on the acoustic properties (i.e., velocity and attenuation) of mammalian tissues in the megahertz range of frequencies used in medical ultrasonics. The actual values reported have been quoted to present a clear picture of the current state of knowledge in order to enable it to be assessed and to enable future workers to compare their own results directly. In the 20 years since the last such compilation, the progress in estimating the relative contributions of the animal species, the condition of the tissue, the temperature and frequency at which measurements were made, and the method of measurement to the observed variation has been small. It is hoped that this compilation together with its summarizing tables will both be of practical use to the worker in the field and also encourage the establishment of a stronger body of fundamental information for the application of ultrasonics in biology and medicine.
Calculations of the effects of nonparallelism on measurements of ultrasonic attenuation and velocity
Authors: Calder I. D.
Published: October 2005

When pulse-echo methods are used to measure sound velocity and attenuation, a lack of parallelism between the sound generator and the reflector causes an interference envelope to be superimposed upon the echo train if the attenuation is low. This envelope is calculated for nonzero attenuation and several transducer-reflector configurations: (a) a tilted reflector with pistonlike sound generation, (b) a tilted reflector with an initial nonuniform amplitude distribution on the transducer, and (c) a spherically curved reflector and a nonzero beam deviation. In each case expressions are obtained for the echo envelope, for the positions of the maxima and minima and for corrections to measurements of sound velocity and attenuation. The results are applied to data taken with samples of solid helium.
Adiabatic mode theory of underwater sound propagation in a range-dependent environment
Authors: Nagl Anton , Überall H. , Haug Anton J. , Zarur G. L.
Published: October 2005

For an ocean sound channel whose environmental parameters depend not only on depth, but in a gradual fashion also on range, the wave equation may be separated by the adiabatic range variation method of Pierce [J. Acoust. Soc. Am. 37, 19 (1965)]. This method is used here to calculate underwater sound propagation in a channel with arbitrary (but gradual) range dependence, and also with arbitrary depth dependence of the sound velocity profile, by employing Airy function solutions of segmentwise linearized problems. Our results are illustrated for a realistic deep-water propagation case with profile data collected in the western North Atlantic, as well as a shallow-water example from the Norwegian Sea, and compared against the experimental transmission loss data, and the results of calculations using other methods for the same cases.
Sound dispersion in a quasi-Lorentz gas
Authors: Monchick L.
Published: October 2005

It is shown that some well-known formulas connecting viscous drag and thermal transfer in the continuum to the free molecular flow regime can be used to extend the Temkin–Dobbins formulas for sound dispersion in a dusty gas to very small particle sizes.
Wave propagation in a piezoelectric two-layered cylindrical shell with hexagonal symmetry: Some implications for long bone
Authors: Ambardar Ashok , Ferris Clifford D.
Published: October 2005

Harmonic wave propagation is considered in a two-layered cylinder of dissimilar but transversely isotropic materials such as bone. The model includes the approximate piezoelectric behavior of long bone and the frequency equation is shown to constitute a 16th-order determinant. A frequency equation is also derived for the nonpiezoelectric case. Though the frequency equations are much too complicated to be treated analytically, they are shown to lead to simpler forms for the special cases of axial symmetry, very long and very short wavelengths. In the absence of established values for the piezoelectric moduli of bone and of the elastic constants of the inner spongy layer, a numerical solution to the model does not seem worthwhile at present.
Large-amplitude vibration of oblique panels
Authors: Srinivasan R. S. , Ramachandran S. V.
Published: October 2005

This paper deals with the large-amplitude free vibration of skew plates having variable thickness. Two governing nonlinear differential equations in terms of the lateral deflection and ’’force function’’ are derived in the oblique coordinates. The edges of the plate are assumed to be clamped and free to move in the plane of the plate. The differential equations together with the boundary conditions are transformed into nonlinear algebraic equations by using the integral equation for beams along the oblique directions. These algebraic equations are then solved by the Newton–Raphson procedure. Numerical work has been done and graphs showing period versus amplitude are presented for different values of thickness parameter, skew angle, and aspect ratio.
Echosonde interferometer for atmospheric research
Authors: Brown Edmund H. , Little C. Gordon , Wright Wayne M.
Published: October 2005

A preliminary version of an echosonde interferometer is described and some of the first results obtained with it are presented. The results demonstrate that the formation of an acoustic interference pattern from a pair of coherent sources extends to the sound field scattered by turbulent fluctuation and that an echosonde interferometer is practicable. Possible applications to the remote sensing of atmospheric temperature profiles are discussed.
Model experiments on surface waves
Authors: Donato R. J.
Published: October 2005

Experiments are described in which exponential attenuation factors for surface waves both in the direction of propagation along a complex impedance surface and perpendicular to the surface are measured. The surface impedance calculated from these attenuations is then compared to that measured in an impedance tube.
Application of a quartz crystal with electrode-tab configuration for simultaneous mass and temperature determination
Authors: van Ballegooijen E. C. , Boersma F. , van der Steen C.
Published: October 2005

In this paper the possibility of using a quartz crystal coated with electrodes and a tab for simultaneous mass and temperature determinations is investigated. The practical applicability of the recently introduced method, based on the properties of the resonant frequencies of an electrode-tab system, strongly depends on the accuracy by which mass and temperature can be determined. It is shown from the experiments presented in the paper that the accuracy of the method is strongly improved by measuring the temperature with the help of the higher-order harmonic overtones related to the electrodes, and by measuring the mass with the help of the fundamental resonant frequency related to the tab. An analysis to determine the error in the mass and temperature, resulting from calibration and experimental errors, is given. The results from the analysis show that a mass change of 10 Å (copper) and a temperature change of 0.01 °C can be determined within 3% and 18%, respectively. Some suggestions are given for further improvement of the method in order to make it useful for practical applications.
Psychological Assessment of Aircraft Noise Index
Authors: Hayashi Chikio , Kondo Susumu , Kodama Habuku
Published: October 2005

The aim of this paper is to describe the nature and development of a new index called Psychological Assessment of Aircraft Noise Index (PAANI). An intervening variable UFR (Unfavorableness Ratio) is used without setting directly the relation between psychological measurements and psychological reaction of the inhabitants to aircraft noise as is done for  Weighted Equivalent Continuous Perceived Noise Level  and  Noise and Number Index.  UFR is made for an aircraft by using the  Theory of Quantification,  which evaluates the physical measurements (maximum A-weighted noise level, duration of noise above 70 dB, and frequency spectra of the noise). The characteristic I (r) of the noise at the rth location is defined as the number of aircraft over fixed value of UFR on the distribution of UFR calculated from the aircraft passing over the location. While the psychological reaction to noise of the inhabitants in the rth location is estimated from data obtained by a social survey, the PAANI is determined from the distribution of Guttman scores of noise reaction shown by the inhabitants in the location. The characteristics of I30(r), which is the number of aircraft over 30% of UFR at the rth location, correlates well with the index of psychological reaction of the inhabitants of the rth location for all r locations.
Performance sensitivity of array detectors to a p
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i spatial knowledge
Authors: Liu C. S , Nolte L. W.
Published: October 2005

Performance of array detectors degrades when the a priori spatial knowledge of the signal direction or interfering noise direction is inaccurate. Two classes of signal waveforms are considered; one is the known-waveform signal, the other is the Gaussian signal. For the known-waveform-signal case, an explicit functional form is derived for the detectability index to characterize the degraded receiver-operating-characteristic (ROC) curve which is due to either mismatch of signal direction or inaccurate noise direction. For the Gaussian-signal case, the distribution of the sufficient statistic is shown to be a ’’generalized chi-square distribution.’’ Then, the performance and its sensitivity to the signal-direction mismatch are evaluated in terms of probability of detection (PD) and probability of false alarm (PF). Closed form expressions for PD and PF are shown for a single-frequency case. The array factor, which depends on the geometry of the array sensors, plays an important role in the sensitivity study. For the Gaussian signal in independent noise, the performance loss of the processor is a function of the array factor and the angular distance between the true source location and the assumed source location. For the known-waveform signal in independent noise, performance degradation is closely related to the array factor. The detectability index for the known-waveform signal, with directional noise, is related in a more complicated way to the array factor. In general, a low-directivity array is desirable in the incorrect signal-direction cases and a high-directivity array is desirable in the incorrect noise-direction cases. By comparing the relative detection performance degradation of the known-waveform signal processor with that of the Gaussian-signal processor, we conclude that the Gaussian-signal processor is less sensitive to the uncertainty than is the known-waveform processor. This is due to the fact that the received signal phase which is used in the known-waveform signal processor, is more sensitive to the inaccuracy of the spatial knowledge than is the received-signal energy which is used in the Gaussian-signal processor.
The effect of amplitude envelope on the pitch of sine wave tones
Authors: Hartmann W. M.
Published: October 2005

Psychophysical experiments show that the pitch of a short sine wave tone depends upon the amplitude envelope of the tone. Subjects find that the pitch of an exponentially decaying tone (1dB/ms) is higher than the pitch of a (20-ms) rectangularly gated tone of equal frequency. The percentage difference in frequency required to produce equal pitches with the two envelopes depends upon frequency f0: 2.6% at f0=412 Hz, 1.4% at f0=825 Hz, 1% at f0=1650 Hz, and 0.7% at f0=3300 Hz. The pitch change is insensitive to the relative intensities of the two tones. The spectra of tones with the two different envelopes suggest no obvious explanation for the pitch change. However, the weighted time-varying spectra for tones with two different envelopes evolve differently with time. Alternatively the pitch change can be derived from a modified version of the auditory phase theory of Huggins.
Binaural detection at high frequencies with time-delayed waveforms
Authors: McFadden Dennis , Pasanen Edward G.
Published: October 2005

Recent research has demonstrated that the binaural system can utilize ongoing interaural time differences for lateralization at high frequencies as well as at low frequencies. The requirement is that the signal be complex so that the time difference appears as a delay in the envelope of the waveform at one ear. Reported here are several masking experiments that examine detection performance with time-delayed signals or maskers. In the first experiment, the signal was a 50-Hz band of noise centered at 4000 Hz that was time delayed by different amounts on different blocks of trials; the masker was a similar band of noise, presented diotically. Large masking-level differences (MLDs) were obtained for some values of time delay, but the MLDs did not increase monotonically with time delay as they should were envelope time delay the basis for detection performance. Subsequent experiments, in which the masker was time delayed and the signal was a diotic, high-frequency tone, revealed that detectability follows the autocorrelation function, and that MLDs as large as 24 dB can be obtained at 4000 Hz at time delays corresponding to negative values in the autocorrelation function. Examination of the signal-plus-masker waveforms in these conditions reveals that ongoing interaural differences in level and cycle-by-cycle time exist in those conditions that yield MLDs. Since the time differences are small by usual standards, the basis for detection performance in these conditions appears to be the ongoing interaural level differences. In a final experiment, lateralization performance was measured for a time-delayed, complex waveform in the presence of maskers of various intensities. The results show that subjects are able to extract information about the time delay in the envelope even when the signal is added to a masker of equal intensity or greater. Thus, at the small signal-to-noise ratios used in our detection experiments, extraction of envelope time information was impossible, but also unnecessary, for detection was accomplished on the basis of another cue—most likely the ongoing interaural level differences.
Impedance of acoustic and structural waveguides at their cutoff frequencies
Authors: Junger M. C.
Published: October 2005

Two classes of waveguides are studied: acoustic waveguides conducting pressure waves generated by a constant-velocity source; and structural waveguides excited by a constant force shaker. The high-pass cutoff frequencies of propagating modes of both waveguide classes equal the natural frequencies of the corresponding standing-wave modes of the waveguide cross section. In acoustic waveguides, cutoff frequencies correspond to an infinite impedance at the source. In structural waveguides, cutoff frequencies coincide with vanishing drive-point impedance, the resonant mode short circuiting the other modes. This distinctive behavior is associated with the prescribed excitations and definition of drive-point impedance rather than with the nature of the waveguide.
Radiation pressure—the history of a mislabeled tensor
Authors: Beyer Robert T.
Published: October 2005

The acoustic radiation pressure has found practical application in recent years in instruments measuring sound intensity and in experiments on acoustic levitation. The concept of radiation pressure has, however, long fascinated both optical and acoustical physicists. The history of light radiation pressure goes back more than 200 years to Leonhard Euler, while the concept of acoustic radiation pressure dates from the time and work of Rayleigh. It was pointed out by Brillouin that what we call radiation pressure is not a pressure at all, but a diagonal tensor, all the diagonal terms of which are not identical. The size of the effect is small, and the values obtained for the radiation pressure are very sensitive to boundary conditions and to the approximations that must necessarily be employed. In addition, although the phenomenon is primarily one of nonlinear acoustics, it can be observed down to the lowest sound intensities under certain conditions. Thus, the Rayleigh radiation pressure vanishes for the linear case, but the usually measured Langevin pressure does not. It might be said that radiation pressure is a phenomenon that the observer thinks he understands—for short intervals, and only every now and then.
Experimental demonstration of the absorption of sound by sound in water
Authors: Moffett Mark B. , Konrad William L. , Carlton Lynn F.
Published: October 2005

Intense low-frequency sound can severely attenuate sound of higher frequencies via spectral redistribution. On the other hand, intense high-frequency sound does not appreciably alter a lower-frequency sound field. An experiment is described wherein a 68-kHz underwater sound beam was made to propagate collinearly with a 244-kHz beam, demonstrating the absorption of sound by sound. The results are in good agreement with the theory of F. H. Fenlon [J. Acoust. Soc. Am. 51, 284–289 (1972)].
Point source moving above a finite impedance reflecting plane— experiment and theory
Authors: Norum T. D. , Liu C. H.
Published: October 2005

A widely used experimental version of the acoustic monopole consists of an acoustic driver of restricted opening forced by a discrete frequency oscillator. To investigate the effects of forward motion on this source, it was mounted above an automobile and driven over an asphalt surface at constant speed past a microphone array. The shapes of the received signal were compared to results computed from an analysis of a fluctuating-mass-type point source moving above a finite impedance reflecting plane. Good agreement was found between experiment and theory when a complex normal impedance representative of a fairly hard acoustic surface was used in the analysis.
Revised estimate of minimum audible pressure: Where is the ’’missing 6 dB’’?
Authors: Killion Mead C.
Published: October 2005

Eardrum pressures at hearing threshold have been calculated from both earphone data (ISO R389−1964 and ANSI S3.6−1969) and free-field data (ISO R226−1961). When head diffraction, external-ear resonance, and an apparent flaw in ISO R226 are accounted for in the free-field data, and real-ear versus coupler differences and physiological noise are accounted for in the earphone data, the agreement between the two derivations is good. At the audiometric frequencies of 125, 250, 500, 1000, 2000, 4000, and 8000 Hz, the estimated eardrum pressures at absolute threshold are 30, 19, 12, 9, 15, 13, and 14 dB SPL, respectively. Except for the effects of physiological noise at low frequencies, no evidence of the ’’missing 6 dB’’ is seen, an observation consistent with the experimental results of several recent studies.
Low-level pure-tone masking: A comparison of ’’tuning curves’’ obtained with simultaneous and forward masking
Authors: Vogten L. L. M.
Published: October 2005

Simultaneous and forward pure-tone masking are compared, using a fixed-level probe of 20-ms and a 200-ms masker. For a 1-kHz probe of 30 dB SPL the required masker level Lm is measured as a function of the time interval Δt between masker offset and probe onset. When masker and probe have equal frequencies a monotonic relationship is found for phase π/2 but not for phase 0. When the masker frequency fm is 50 or 100 Hz below the probe frequency fp a nonmonotony is found, with a minimum at Δt=0, the transition between simultaneous and forward masking. When fm is 50 or 100 Hz above fp, however, the relationship of Lm to Δt is monotonic. In the case of simultaneous masking the iso-Lp curves, which give Lm as a function of fm, show a typical asymmetry around fm=fp, leading to the positive shift of the maximum masking frequency MMF previously reported for stationary pure-tone maskers. In the case of forward masking, however, this asymmetry ceases to exist. We conclude that simultaneity of probe and masker is a necessary condition for the occurrence of a low-level positive MMF shift. The results are discussed in the light of psychoacoustical and neurophysiological data on two-tone suppression. A possible interpretation of the nonmonotony and of the positive MMF shift is suggested in terms of the physiological asymmetry in two-tone suppression.
Inversion of articulatory-to-acoustic transformation in the vocal tract by a computer-sorting technique
Authors: Atal B. S. , Chang J. J. , Mathews M. V. , Tukey J. W.
Published: October 2005

We present numerical methods for studying the relationship between the shape of the vocal tract and its acoustic output. For a stationary vocal tract, the articulatory-acoustic relationship can be represented as a multidimensional function of a multidimensional argument: y=f(x), where x, y are vectors describing the vocal-tract shape and the resulting acoustic output, respectively. Assuming that y may be computed for any x, we develop a procedure for inverting f(x). Inversion by computer sorting consists of computing y for many values of x and sorting the resulting (y,x) pairs into a convenient order according to y; x for a given y is then obtained by looking up y in the sorted data. Application of this method for determining parameters of an articulatory model corresponding to a given set of formant frequencies is presented. A method is also described for finding articulatory regions (fibers) which map into a single point in the acoustic space. The local nature of f(x) is determined by linearization in a small neighborhood. Larger regions are explored by extending the linear neighborhoods in small steps. This method was applied for the study of compensatory articulation. Sounds produced by various articulations along a fiber were synthesized and were compared by informal listening tests. These tests show that, in many cases of interest, a given sound could be produced by many different vocal-tract shapes.
The upper limit of underwater auditory frequency discrimination in the California sea lion
Authors: Schusterman Ronald J. , Moore Patrick W.
Published: October 2005

It was hypothesized that at similar or even greater sensation levels (SLs) the frequency discrimination of the sea lion (Zalophus californianus) in water would be much poorer in the range of frequencies between 32 and 48 kHz than it would be between 16 and 28 kHz. Difference limens were estimated for frequencies of 16, 24, 28, 34, and 38 kHz. Results clearly supported this hypothesis. Between 16 and 28 kHz, the Weber ratio (ΔF/F) was 20 or, in other words, Zalophus could discriminate frequencies in this range which were 2.0% apart. At 34 kHz, frequency resolution became twice as coarse as it was at 28 kHz. Performance at 38 kHz deteriorated to such an extent that the sea lion was capable of only discriminating frequencies which were 11.2% apart. The present results showing a loss of good frequency resolution much above 32 kHz in Zalophus despite increased SL as compared to the loss of frequency resolution in phocids above 60 kHz are consistent with the notion that one of the major differences between the underwater hearing of otariids and phocids is the high-frequency cutoff. Although the sample of species and individuals involved in behavioral comparisons is very small, comparative anatomical evidence supports the idea that in water phocids obtain more spectral information from high frequencies than do otariids.
A new artificial ear for telephone use
Authors: Modena Giulio , Reolon Aldo
Published: October 2005

Up until today the CCITT has recommended provisionally the use of the IEC artificial ear as an acoustic load to measure the sensitivity/frequency curve for telephone receivers. This artificial ear was obtained for audiometric requirements. In the telephone use the acoustic leak greatly influences the acoustic load. In this paper we describe an automatic system for the impedance measurement in module and phase versus frequency of the human ear measured during the telephone use. The measurements were obtained with a telephone handset in a normal use. The telephone handset was the acoustic source. A microphone probe at the handset auricle center drew the acoustic pressure. Measurements were made on 50 subjects at two different sound levels. After obtaining the electric simultation of the acoustic impedance shape we built a prototype of a new artificial ear for telephone use. The results obtained using constructed prototypes are shown. Measurements were carried out of the response curves of three different telephone receivers inserted in three types of handsets. The results obtained using human subjects are compared with those obtained using the IEC artificial ear and the new artificial ear for telephone use.
Prototype of bispectral passive imaging systems aiming machine-system diagnosis
Authors: Sato Takuso , Sasaki Kimio , Nonaka Masaharu
Published: October 2005

A prototype of bispectral passive imaging system designed for the diagnosis of machine systems from their noises is presented. The principle is generalized aiming machine-system diagnosis and the concrete construction of scanner of a microphone and the details of the signal processings as well as the obtained images are shown. Typical characteristics of the system are as follows: (a) images to be reconstructed, spatial distribution of the degree of interference among three frequency components or spatial distribution of intensity of noises emitted from the object; (b) maximum resolution, 15/f cm where f is the used frequency (f=0.5∠10 kHz); (c) time required to obtain one image, from 30 to 90 min depending on the number of sampling points; (d) display of result, print out on a typewriter or colored display on a TV monitor.
Attenuation in surface ducts
Authors: Mellen R. H. , Browning D. G.
Published: October 2005

Two surface duct propagation experiments are examined in which absorption and diffraction appear to be the dominant attenuation mechanisms. The absence of an excess diffusion loss suggests that little or no internal scatter occurs in a mixed layer. This result is consistent with the internal wave scatter hypothesis.
Responses of two suddenly coupled strings for random forcing functions
Authors: Okada Kiyoshi , Sato Takuso , Sasaki Kimio
Published: October 2005

The nonstationary responses of two strings suddenly coupled by a spring at a fixed point are discussed. The initial conditions for two strings are given statistically as the stationary responses for independent white random inputs. The coupling is taken place when the distance between coupling points of two strings coincides with the natural length of the spring. Numerical examples are also given by using the characteristics of the real, double, simple, catenary trolley lines as the parameter of the system.
A-weighted equivalents of permissible ambient noise during audiometric testing
Authors: Killion M. C. , Studebaker G. A.
Published: October 2005

Using the relative octave band levels obtained by Botsford [Sound Vib. 3, 16–28 (1969)] for various noise spectra, it is possible to calculate the A- and C-weighted sound levels of typical noises just meeting the requirements of ANSI S3.1-1977. Such a calculation indicates an A-weighted sound level of approximately 15 dB is required to meet the maximum permissible octave band levels for testing at audiometric zero in the ears-not-covered condition. For the average typical curves shown by Botsford, the calculated A-weighted sound levels range from 14.0 to 16.5 dB. For the case where the ear is covered by an earphone mounted in an MX-41/AR cushion, an A-weighted level of 22 dB or less appears to be required. For applications requiring determination of hearing threshold down to the conventional upper limit of ’’normal hearing,’’ (25 dB HL) the corresponding A-weighted noise levels are 40 dB for sound field testing and 47 dB for earphone testing.
Spectral structure of an ultrasound wave scattered by a random surface: Application to the scattering of sound from the sea surface
Authors: Gazanhes C. , Leandre J. , Lefebvre J. P.
Published: October 2005

The scattering of a sound wave by the sea surface is accompanied by random fluctuations of amplitude and phase which depend on the surface conditions. A theoretical model based on Helmholtz’s theorem is proposed, which leads to a simple expression for the power spectral density of a scattered signal. This expression permits a computer simulation of the phenomena to be made that may be verified experimentally by means of spectral analysis. The technique employed leads to a resolution of 0.25 Hz. The experiments were conducted on a reduced model in an acoustic tank. Measurements were made using a monochromatic signal of 150 kHz for specular reflection and for three different surface conditions. The results of the numerical simulation are in good agreement with experiment.
Deep-water acoustical analysis of stationary and moving broadband sound sources
Authors: Jacyna G. M. , Jacobson M. J.
Published: October 2005

Deep-water sound transmission from a moving source to a fixed receiver is studied, where the source emits a random broadband signal whose expected distribution is normal. A bilinear sound-speed profile is employed, the source is located above the SOFAR axis, and the receiver below. Long ranges are assumed, so that only SOFAR rays need be considered. Basic propagation equations are given, and travel time and spreading loss expressions are approximated in stability regions within which all four SOFAR rays exist for each number of SOFAR-axis crossings. General equations are derived for the received average power spectrum and power in terms of the spectrum at the source. Then, the broadband signal is taken to be bandlimited white noise. The received spectrum is simplified and examined for nonmultipath, multipath, and Doppler contributions. The influences of range, source speed, frequency, and observation time are considered. Average power at the receiver is studied similarly. Received spectra for a stationary source are investigated, and exhibit greater variations than those arising from a moving source. However, received average power for stationary and moving broadband sources are about equal. Average received power from cw and broadband sources, both moving and stationary, are compared. Power variations in the cw case are found to be much larger than in the broadband case.
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 is made of the sound field in a sand sediment due to a parametric array located in the overlying water. The following approximations are used. First, the array is represented by a line distribution of end-fired virtual sources. Secondly, the ray method is used to calculate the sound field in the sand from each source. Attenuation in the sand is treated as a perturbation. That is, the ray paths are found for an equivalent lossless medium, while the fields along these paths are obtained using the measured attenuation coefficient of the sand. The sound field of the array is then calculated by summing the contributions from the line distribution of virtual sources extending from the projector to the sand surface. Numerical results are obtained for array grazing angles in the range 10°–40° and for difference frequencies of 5, 10, and 20 kHz. The results are compared with experimental data.
Multiple scattering of elastic waves by cylinders of arbitrary cross section. I. SH waves
Authors: Varadan Vijay K. , Varadan Vasundara V. , Pao Yih-Hsing
Published: October 2005

A scattering matrix approach, that involves only the transition matrix of a single obstacle, is proposed for studying the multiple scattering of elastic waves in a medium (matrix) containing identical, long, parallel, randomly distributed cylinders of arbitrary cross section. The elastic properties of the cylinders are assumed to be different from those of the matrix. A statistical approach in conjunction with Lax’s ’’quasicrystalline’’ approximation is employed to obtain equations for the average amplitudes of the scattered and exciting fields which may then be solved to yield the dispersion relations of the composite medium. Dynamic elastic properties of the composite medium containing circular and elliptical cylinders are found in the Rayleigh or low-frequency limit. Numerical results displaying phase velocity and damping effect of the composite medium are presented for a wide range of frequencies.
Fourth-order acoustic torque in intense sound fields
Authors: Wang T. G. , Kanber H. , Olli E. E.
Published: October 2005

We report the first observation of a fourth-order acoustic torque in intense sound fields. The torque was determined by measuring the acoustically induced angular deflection of a polished cylinder suspended by a torsion fiber. This torque was measured in a sound field of amplitude greater than that in which first-order acoustic torque has been observed.
A comparison of Doppler sodar antenna configurations used for horizontal wind measurement
Authors: Davey Robert F.
Published: October 2005

The performance of two antenna configurations is evaluated using a parametric optimization technique that predicts the relative accuracy of horizontal wind measurement. Consideration is given to the effect of atmospheric attenuation and the relation between the thermal- and velocity-structure parameters as well as to the geometric effects. Using a baseline case with a maximum measuring altitude of 500 m, optimum antenna orientations are determined for the familiar axisymmetric three-transmitter configuration and for a two-transmitter system using a tilted receiver antenna. The sensitivity of each system to small changes in the geometry and to modifications in the assumed attenuation and structure parameter ratio is examined. The two-transmitter system is found to generate velocity measurements with accuracy comparable to the three-transmitter geometry at the design point. However, the effect of the preferred orientation at lower heights results in poorer comparative performance.
Method for computing motion in a two-dimensional cochlear model
Authors: Sondhi Man Mohan
Published: October 2005

We describe an effective technique for computing the steady-state motion in a two-dimensional cochlear model. With the cochlear fluid assumed incompressible and inviscid, the problem reduces to solving Laplace’s equation for a region with a yielding boundary (corresponding to the basilar membrane). From an integral equation representation of this solution, a pair of second-order differential equations is derived. The solution of these differential equations gives the velocity of the basilar membrane and hence other related quantities, e.g., displacement, pressure, driving-point impedance at the stapes. Higher-order approximations, as well as extensions to nonlinear membranes are discussed.
Comment on ’’Acoustic diffraction of a plane wave by a semicircular infinite soft strip’’ [J. Acoust. Soc. Am. 62, 250–254 (1977)]
Authors: Corrington Murlan S.
Published: October 2005

The hypergeometric series used in the paper can be summed in closed form.