bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation of beamed signals through inhomogeneous media: A diffraction theory
Authors: McCoy J. J. , Beran M. J.
Published: October 2005

A theory, which is suitable for making estimates of the acoustic field radiating from either a completely coherent (i.e., deterministic) or a partially coherent source is derived and discussed. The theory outputs are measures of beam bending and spreading due to refraction and diffraction. For the random source problem, the theory also provides estimates of the coherence of signals received by pairs of spatially separated hydrophones. The theory is based on an approximation that may nominally be termed parabolic. The limits of validity of the various approximations are discussed and a solution algorithm, which might be classified as an extended ray-trace algorithm, is presented. A special case, in which this algorithm can be carried out analytically, is dicussed.

Subject Classification: [43]30.20; [43]60.20; [43]30.35; [43]20.30.
Long-range acoustic propagation paths: Antigua–Newfoundland
Authors: Nutile D. A. , Guthrie A. N. , Fitzgerald R. M. , Shaffer J. D.
Published: October 2005

The propagation paths from shallow explosive sources to a SOFAR axial receiver are determined by analyzing measured shot signatures. The charges were detonated along a 2800-km track between Antigua and Newfoundland. Propagation was through several distinct water masses, each of which produced different observable effects on the shot signature. Because of the shallow depth of the source, the number of turning points below the SOFAR axis is the prime determinant of the time dispersion of the arrivals and is a convenient basis for classifying them. The range dependence of the dispersed arrivals depends on the large-scale oceanography and discloses the identity of the ray paths which produce it.

Subject Classification: [43]30.20.
Acoustic signatures from deep water implosions of spherical cavities
Authors: Orr Marshall , Schoenberg Michael
Published: October 2005

Hollow glass spheres of various sizes have been preweakened to implode at ocean depths of approximately 3 km and sunk using chain weight. Acoustic signals generated from the implosion of these spheres have been analyzed. Pressure signatures, energy-density spectra, and total acoustic energy in the frequency band 96–5000 Hz are presented. The signatures of all the implosions have many features in common. Basically each consists of a low flat negative-pressure pulse followed by a sharp positive-pressure spike of roughly 0.2-msec duration. The efficiency of the conversion of available potential energy to radiated acoustic energy is approximately 18%. Total radiated acoustic energy for spheres of 43.2-cm diameter imploding at a 3-km depth is about 53 dB re 1 J. Preweakened glass spheres show promise as a tool in the study of the sedimentary structure of the ocean bottom due to the impulsive character of the signal that is radiated upon implosion.

Subject Classification: [43]30.50, [43]30.60, [43]30.70.
Hidden depths: Acceptable ignorance about ocean bottoms
Authors: Williams A. O.
Published: October 2005

Normal-mode analysis of underwater sound propagation in principle requires knowledge of pertinent physical parameters at all depths in the water and the bottom material—an unattainable omniscience. We present a method for determining the maximum depth to which this knowledge is necessary in order to hold the fractional errors in mode eigenvalues to prescribed limits. Let hn represent a vertical distance below the lower turning point of the nth-mode solution. Insertion or removal of a horizontal plane reflector, at this depth, alters the mode eigenfunction and therefore the eigenvalue En. The fractional error ΔEn/En is a calculable function of hn; this error being stipulated, hn can be found. The calculation need be made only for the highest mode that contributes significantly. Conversely, if all parameters are known to depth h, the consequent errors can be found. Two examples are analyzed, with simplifying restrictions: deep isovelocity water, low frequencies, many modes, bottoms that are isovelocity (the Pekeris case) or have a positive gradient of sound speed. For fractional errors of 10−4 to 10−6, h is a few acoustic wavelengths. In each example, bottom absorption has little effect on the result.

Subject Classification: [43]30.20, [43]30.50, [43]30.25.
Convergence of an iterative solution for a class of nonlinear vibration problems
Authors: Stani?ić M. M.
Published: October 2005

A nonlinear equation describing the motion of a nonlinear oscillator has been reduced by proper substitution to an integro-differential equation and then solved by means of an iterative technique for an arbitrary forcing function. The effect of the nonlinear terms on the convergence has been studied. It has been shown that such a solution converges sectionally in an interval Δτ. An inequality has been determined which yields a maximum Δτ regardless of the form of the forcing function if ε=0. However, for a nonzero ε the interval of convergence is highly dependent of the form of the forcing function.

Subject Classification: [43]40.30, [43]40.20.
Power spectral representation of nonstationary random processes defined over semi-infinite intervals
Authors: Mark William D.
Published: October 2005

A new sequence of locally time-averaged power spectra is defined that describes the time evolution of the frequency content of nonstationary random processes and linear system impulse response functions. The exact input-response relations for these spectral sequences are shown to be finite discrete convolutions of the input and system spectral sequences. Expressions for the coefficients of a Laguerre function expansion of the time-varying mean square response are derived from the response spectral sequence, and the time resolution and convergence of the expansion are discussed. Simple formulas are derived for generation of the spectra from recorded sample functions using Fourier transform computational algorithms. The relationship of the spectra to the Laplace transform is also developed. Physical interpretation of the spectra is discussed in detail and related to the uncertainty principle for Fourier transforms.

Subject Classification: [43]45.40; [43]60.20; [43]20.50; [43]30.30; [43]40.35.
Binaural interaction in cat and man. II. Interaural noise correlation and signal detection
Authors: Geesa Ben H. , Langford Ted L.
Published: October 2005

Detection of diotic 500-Hz tones partially masked by diotic and dichotic noise was measured for two cats and two human observers. The interaural correlation of the masker was varied in five steps from +1.0 to −1.0 mixing a noise common to each ear with that from two independent noise sources. For the cats, an avoidance response was used to measure the detectability of the signal. As found in other studies, the sensitivity of the cat in the homophasic condition was less than that of man and smaller MLD’s were obtained for the cat in the antiphasic conditions. An indirect estimate of the binaural critical band for the cat is larger than that for man. Subject Classification: [43]65.58, [43]65.62; [43]80.50; [43]65.75.
Acoustic reflex threshold of the chinchilla as a function of stimulus duration and frequency
Authors: Woodford C. M. , Henderson D. , Hamernik R. P. , Feldman A. S.
Published: October 2005

Acoustic reflex thresholds and the threshold-duration function were obtained from 27 chinchilla. The reflex threshold was found to be approximately 20 dB lower than that of man with a small frequency effect evident after correction for sound pressure transformation function of the pinna and external auditory meatus. The temporal integration function reflected by acoustic reflex threshold is of much greater magnitude than that obtained psychophysically in chinchilla and man.

Subject Classification: [43]65.50, [43]65.24, [43]65.68.
Linguistic uses of segmental duration in English: Acoustic and perceptual evidence
Authors: Klatt Dennis H.
Published: October 2005

The pattern of durations of individual phonetic segments and pauses conveys information about the linguistic content of an utterance. Acoustic measures of segmental timing have been used by many investigators to determine the variables that influence the durational structure of a sentence. The literature on segmental duration is reviewed and related to perceptual data on the discrimination of duration and to psychophysical data on the ability of listeners to make linguistic decisions on the basis of durational cues alone. We conclude that, in English, duration often serves as a primary perceptual cue in the distinctions between (1) inherently long verses short vowels, (2) voiced verses voiceless fricatives, (3) phrase-final verses non-final syllables, (4) voiced versus voiceless postvocalic consonants, as indicated by changes to the duration of the preceding vowel in phrase-final positions, (5) stressed verses unstressed or reduced vowels, and (6) the presence or absence of emphasis.

Subject Classification: [43]70.40, [43]70.70, [43]70.20.
Dimensionless parameters for use in presenting acoustical data
Authors: Romer I. Carl
Published: October 2005

A dimensional analysis of the equations of continuity, momentum, and energy is performed which yields independent dimensionless parameters for use in presenting monochromatic acoustical data. These parameters include the heat capacity ratio γ and the Prandtl number cpμ/k of the material through which the sound is transmitted, an acoustical Reynolds number ρL2ω/μ, and the dimensionless group Lω/c. To illustrate the use of these parameters, the classical Kirchhoff–Helmholtz formulae for sound propagation through gases contained in tubes have been presented in dimensionless form.

Subject Classification: [43]20.15, [43]20.35.
Dichotic pitch fusion
Authors: van den Brink G. , Sintnicolaas K. , van Stam W. S.
Published: October 2005

The frequency limits within which dichotic pitch fusion occurs have been measured as a function of the frequency. The relative frequency differences for the centers of the fusion frequency bands for pure tones coincide with those for binaural diplacusis at corresponding frequencies. A complex (residue) sound fuses only if the fusing conditions for all its individual spectral components are fulfilled. Dichotic fusion of repetition pitch (produced by mixing noise with the same noise, delayed) occurs only if the same noise source is used to produce the signals that are presented to the two ears. Some additional data are presented from experiments with dichotic stimulation with tones of different intensities, where a monotic pitch shift towards the loudest signal is found.

Subject Classification: [43]65.54, [43]65.62.
Modification of vocalizations of preschool deaf children by vibrotactile and visual displays
Authors: Goldstein Moise H. , Stark Rachel E.
Published: October 2005

Three groups of four preschool children who were profoundly deaf or had severe hearing impairment were given training to produce constant–vowel (CV) syllables. One group palpated a vibrotactile vocoder-type display of the acoustic signals. One group used an analogous visual display. Children in the third (control) group were given reinforcement in the form of slide or puppet displays. In the initial sessions, all three groups of children were trained to vocalize in response to a ’’light out’’ signal. No displays were used. The children were then trained to pay attention to the displays and to model CV syllable series presented by the experimenter. In the final sessions all three groups of children were given a model CV syllable series and encouraged to respond by vocalizing when given the microphone and a ’’light out’’ signal. At the same time they had to attend to the tactile, visual, or nonspeech display. The ratio of CV syllables to all syllables, (CV+V), was calculated for each child for the initial and for the final sessions, and the difference score obtained. The paired observation t-test indicated a significant increase in the ratio for the experimental groups and no significant change for the control group. We conclude that the acoustically driven nonauditory displays were an essential factor in the observed change in CV production.

Subject Classification: [43]70.75; [43]65.82, [43]65.64, [43]65.70.
Time-domain formulation of the Doppler effect
Authors: Braun S.
Published: October 2005

Subject Classification: [43]20.30, [43]20.55; [43]28.20.
Comments on ’’Influence of rotary inertia and shear deformation on acoustic transmission through a plate’’ [J. Acoust. Soc. Am. 58, 741–745 (1975)]
Authors: Young J. W.
Published: October 2005

The transmission loss of an acoustic plane wave through a steel plate in water has been computed using Timoshenko–Mindlin plate theory and exact elasticity theory. Good agreement between the two models is found up to a frequency–thickness product of 20 kHz in. At 40 kHz in. and above, limitations of the plate theory approach become apparent.

Subject Classification: [43]30.50; [43]20.60; [43]40.24; [43]20.30.
Auditory discrimination of the onset–offset phase of tone bursts
Authors: Rajcan Emil
Published: October 2005

The difference limen for onest–offset phase was measured for tone bursts with an integer number of periods, rectangular envelopes, and durations between 4 and 128 msec. The difference limen was found to be smaller at 1000 Hz than at 250 and 4000 Hz, and to increase as the duration of impulses increased.

Subject Classification: [43]65.60, [43]65.75.
Additional sound absorption measurements in near-freezing sea water
Authors: Garrison G. R. , Early E. W. , Wen T.
Published: October 2005

Sound propagation measurements at 10, 20, 30, 40, and 60 kHz were made in April 1974 under the ice pack near Pt. Barrow, Alaska. Absorption coefficients were calculated for each frequency and have been reported in detail [G. R. Garrison et al., J. Acoust. Soc. Am. 58, 608–619 (1975)]. In April 1975, an attempt was made to furnish more accurate results at the lower frequencies by measuring the absorption at 7, 13, 20, 30, and 60 kHz. The 1975 measurements gave the following results for the absorption coefficients dB/kyd at a temperature of −1.6 °C and a salinity of 32%: 0.2±0.4 at 7.1 kHz; no data at 13 kHz because of transducer failure; 3.9±0.2 at 20 kHz; 7.2±0.3 at 30 kHz; and 13.1±0.5 at 60 kHz. These values indicate a relaxation frequency, due to MgSO4, of 36±3 kHz, which is slightly above our previous results, but still much lower than that predicted by the Schulkin–Marsh equation for a temperature of −1.6 °C.

Subject Classification: [43]30.20.
Spatial and temporal fluctuations of acoustic signals propagated over long ocean paths
Authors: Williams Ross E. , Wei Chao H.
Published: October 2005

Acoustic wavefront fluctuations and time-base distortions were measured on a long linear receiving array with a 2000 ft vertical aperture. The receiving hydrophones were buoyed slightly off the ocean bottom in a roughly uniform distribution over the aperture length. Continuous acoustic transmission up to 17.6 h of a hyperbolic FM signal with a frequency sweep from 350 to 450 Hz was used in each of seven experiments at ranges of 145, 250, 495, and 635 NM to measure signal time-base distortions. Simultaneously, wavefront fluctuations were determined from changes in arrival time across the aperture of a 10-msec 400-Hz pulse from the same projector. Wavefront fluctuations, rotations, and distortions were calculated and compared to signal time-base distortions measured on a narrow beam directed toward the incoming arrivals. Both RSR (define) and completely refracted path were insonified. In the total wavefront fluctuation, the rotation part was dominant. However, remarkably small standard deviations ranging from 5 to 15 ft over the entire aperture were found for wavefront rotations and distortions. The spectra of the measured time fluctuations and wavefront rotations and distortions reveal common causes, such as tides, overtides, and internal waves.

Subject Classification:[43]30.20.
Deconvolution processing for a nonuniform array
Authors: McDonough R. N.
Published: October 2005

An ambient acoustic field is assumed to be observed through a delay-and-sum beamformer, in conjunction with a line array of non-uniformly-spaced sensors. The beamformer output power, as a function of steering direction, is related to the angular power density of the acoustic field through a certain integral equation, with the kernel being the known power response pattern of the array. In this note, we present the results of some computer experiments concerned with solving this integral equation by working directly in the angle domain, rather than in the wave-number spectral domain. The method is general for any array, but is of interest mainly in the case of a non-uniformly-spaced array, to which our examples correspond.

Subject Classification: [43]60.20, [43]60.30; [43]30.82.
Multidimensional analyses of judgments about traffic noise
Authors: Cermak Gregory W. , Cornillon Peter C.
Published: October 2005

In a laboratory experiment, human subjects were presented pairs of recorded 1-min traffic sounds. Subjects chose whichever sound of each pair they thought they would rather be exposed to on a regular basis; they also judged the relative dissimilarity of the sounds in each pair. The data were analyzed using multidimensional scaling techniques. The choice data showed that relative aversiveness of the sounds was related mainly to their subjective intensity. The dissimilarity data showed that subjects distinguished sounds on the basis of both subjective intensity and information, independent of intensity, about the source of the sounds. The single physical noise measure most highly correlated with the subjective intensity attribute from both sets of psychological data was Leq, the energy-equivalent sound level. Several new measures of the shape of the average power spectrum, and of the time-dependent variability in dBA levels, failed to add appreciably to the predictive power of Leq alone.

Subject Classification: [43]65.75, [43]65.50; [43]50.70, [43]50.50.
Information extraction from contralateral cues in the detection of signals of uncertain frequency
Authors: Gilliom J. D. , Mills W. M.
Published: October 2005

Observers performed a monaural, yes–no detection task under conditions of signal frequency uncertainty. This frequency uncertainty could be reduced by use of a contralateral cue. The major cue types were a single-tone cue with the same frequency as the potential detection tone and a three-frequency cue with the potential signal frequency as the intermediate component. Performance obtained with a single-tone cue rivaled levels obtained when signal frequency was fixed over a block of trials. Performance with a three- frequency cue, requiring extraction of relevant frequency information, produced performance levels only slightly lower than the single-tone cue condition. Two major conclusions were drawn from the data: (1) The observer, utilizing the single-tone cue, can nearly eliminate the detrimental effects of signal frequency uncertainty. (2) The ’’hearing out’’ process used to extract relevant frequency information from the three-frequency cue is nearly complete. The relatively strong support for Ohm’s law obtained from this study may be due, in part, to the level of the auditory system tapped by the present task.

Subject Classification: [43]65.50, [43]65.75, [43]65.54.
Response of cochlear-nucleus neurons to synthetic speech
Authors: Moore Thomas J. , Jr. John L. Cashin
Published: October 2005

Synthetic speech sounds were used as input signals to the guinea pig’s auditory nervous system. Single-unit responses to these signals were recorded from the cochlear nucleus. The results indicate that considerable information concerning acoustic cues of these signals is encoded within the neural responses.Information concerning formant frequency values, formant transitions within the signals, and rate of impulse excitation is present within the firing patterns of individual neurons.

Subject Classification: [43]65.48; [43]70.30, [43]65.59, [43]65.42.
Effects of bow force and speed on violin response
Authors: Bradley John S.
Published: October 2005

Data obtained from a machine-bowed violin indicates the resulting sound pressure is quite precisely proportional to bow speed and nearly independent of bow force. An estimated maximum possible dynamic range for the violin is calculated.

Subject Classification: [43]75.30.
Maximum directivity factor of nth-order transducers
Authors: Gerzon Michael A.
Published: October 2005

It is proved using general group-theoretic and Hilbert-space methods that the maximum directivity factor obtainable from an nth-order directional acoustic transducer is (n+1)2, that this most directional transducer is axially symmetric, and that its polar response to sounds arriving from an angle ϑ off axis is proportional to

𝒥n/k=0 (2k+1) Pk(cosϑ).

Subject Classification: [43]85.40, [43]85.62.
Propagation of a spherical wave near a plane boundary with a complex impedance
Authors: Donato R. J.
Published: October 2005

An analysis, using complex angles of incidence as the variable in a steepest descents integration, is made of the propagation of sound from a point source over a locally reacting complex impedance boundary. The integration process contains more terms than are normally used in the analysis, and the solution is valid over a large range of horizontal distances. Conditions for the existence of surface waves are discussed in some detail. A comparison is made of measured and calculated values of pressure on the boundary.

Subject Classification: [43]28.40; [43]20.15, [43]20.30.
Propagation of a coherent acoustic wave through a turbulent shear flow
Authors: Ho Chih-ming , Kovasznay Leslie S. G.
Published: October 2005

A collimated ’’monochromatic’’ acoustic wave (sinusoidal wave of 3–90 kHz) was directed across a two-dimensional turbulent jet perpendicular to its plane of symmetry. Extensive study of the statistical properties both of the turbulent medium and of the received signal (random amplitude and phase modulation) offers physical insight into the general phenomenon of a periodic wave (pressure) scattered by random inhomogeneities (solenoidal velocity field).

Subject Classification: [43]28.60.
Vibrational and rotational relaxation in mixtures of water vapor and oxygen
Authors: Bass H. E. , Keeton Roy G. , Williams David
Published: October 2005

Experimental measurements of sound absorption in air, measurements of ultrasonic absorption in H2O/O2 mixtures at 500 °K reported here, and experimental measurements in mixtures of H2O with other impurities have been analyzed to determine the energy transfer rates in mixtures of O2 and H2O as a function of temperature. A set of energy transfer rate coefficients was found that give results consistent with all the experimental data examined and with vibrational energy transfer theory. The rotational relaxation time for H2O/O2 mixtures was determined from the 500 °K ultrasonic measurements.

Subject Classification: [43]35.20, [43]35.35.
Brillouin scattering and attenuation of hypersonic waves in molten NaNO3
Authors: Knape H. E. Gunilla
Published: October 2005

Brillouin spectra of molten NaNO3 have been investigated at two different scattering angles, 40° and 140°, in a temperature interval ranging from 310° to 450 °C. The measured frequency shifts and linewidths of the Brillouin components were used to determine the hypersonic velocity and attenuation of thermal waves in the frequency range 3.4–10.2 GHz. The determination of the Brillouin linewidths has been performed using a convolution technique, necessary when narrow linewidths are to be determined. The hypersonic velocity measurements show no appreciable dispersion compared either to ultrasonic data or to each other. In the line broadening measurements, however, the attenuation shows some dispersion especially at the higher frequencies, thus indicating that the measurements are performed at frequencies just below a relaxation frequency. A calculation of this frequency using a theory with a single relaxation time confirms this assumption.

Subject Classification: [43]35.24; [43]35.30
SBC quarter plane subjected to a transient P wave and its diffraction at grazing incidence
Authors: Ziv M.
Published: October 2005

The paper deals with diffraction of a transient elastic P wave, generated by stress boundary conditions (SBC), as it impinges on a stress-free surface at grazing incidence. The relevant boundary-value problem concerns an impulsive load applied uniformly to the cylindrical surface of an infinite cavity drilled into a half-space. The process thus consists of a quarter plane deformed by a P wave, its diffraction, and reflections from the boundaries. In an earlier work the author gave a general analytical–numerical method for transient multidimensional boundary-value problems and its employment to the present problem. Here, the resultant wavefronts and the response of the quarter plane are described and interpreted.

Subject Classification: [43]20.15, [43]20.30.
Measurement of the combination tones f2−f1 and 2f1−f2
Authors: Zurek Patrick M. , Leshowitz Barry H.
Published: October 2005

A three-alternative forced-choice technique was employed to estimate the phase and amplitude of the combination tone f2−f1 and 2f1−f2. The measurement procedure is based on a simple vector description of combination tone interactions. The task of the observer was to discriminate a change in intensity of the combination tone produced by a change of either the phase or amplitude of the cancellation tone. Measurements of f2−f1 essentially constitute a replication of previously reported data obtained with adjustment techniques. Considerable difficulty was encountered, however, in the measurement of the phase and amplitude of the cubic difference tone. Masking of additional low-frequency combination tones with low-pass noise did not eliminate the problem. It is concluded that phase induced changes in the envelope of the acoustic waveform as well as the magntiudes of higher-order combination tones contribute to a monaural phase effect and hamper the forced-choice measurement of 2f1−f2.

Subject Classification: [43]65.56, [43]65.54, [43]65.60, [43]65.50.
Lateralization of repeated filtered transients
Authors: Yost William A.
Published: October 2005

The lateralization of a high-pass and a low-pass 40 dB SL, 0.1-msec transient was measured as a function of the number of repetitions of the transient and the repetition rate. A high-pass transient presented once required 100 μsec more interaural time for lateralization than did a low-pass transient presented once. Twelve repetitions of the high-pass transient yielded the same lateralization performance as that obtained with a low-pass transient. Repetition rate did not affect the lateralization of the high- or low-pass transients, and number of repetitions did not affect the lateralization of the low-pass transients. These results were compared with results obtained with gated sinusoids presented with and without rise–decay times.

Subject Classification: [43]65.62, [43]65.75, [43]65.58.
Input acoustic-impedance measurement of the subglottal system
Authors: Ishizaka K. , Matsudaira M. , Kaneko T.
Published: October 2005

The input acoustic impedance looking into the trachea was measured on several laryngectomized subjects. The results show remarkable inconsistency with van den Berg’s data. The subglottal resonances are found at approximately 640, 1400, and 2100 Hz. The acoustic input impedance at the first peak ranges between 25 and 50 cgs acoustic ohms. The results are analyzed by means of a digital simulation based on anatomical studies, and the tract wall impedance necessary to produce the measured subglottal impedance is calculated.

Subject Classification: [43]70.20, [43]70.40, [43]35.20.
What information enables a listener to map a talker’s vowel space?
Authors: Verbrugge× Robert R. , Strange Winifred , Shankweiler Donald P. , Edman Thomas R.
Published: October 2005

Prior experience with a talker’s speech contributes little to success in vowel identification. Adult listeners averaged only 12.9% errors on 15 vowels in /h–d/ syllables spoken in mixed order by 30 talkers (men, women, and children), and 17.0% errors on 9 vowels spoken in /p–p/ syllables by 15 talkers. When the /p–p/ test series was spoken by single talkers, errors decreased by less than half to 9.5%. Experience with known subsets of a talker’s vowels did not significantly reduce errors on subsequent test tokens: following the point vowels (/i/, /a/, /u/), errors averaged 12.2% on vowels in /h–d/ context and 15.2% in /p–p/ context; following three central vowels (/I/, /a/, /Λ/), errors averaged 14.9% in /p−p/ context. Precursors mainly influenced listeners’ response biases, rather than facilitating true improvements in vowel identifiability. These results did not support the hypothesis that point vowels provide listeners with unique information for normalizing a talker’s ’’vowel space.’’ Errors on vowels in rapid, destressed /p–p/ syllables (excised from sentence context) averaged 23.8%. Errors jumped to 28.6% when point-vowel precursors were introduced, while presentation of syllables in the original sentences reduced errors to 17.3%. Sentence context aids vowel identification by allowing adjustment primarily to a talker’s tempo, rather than to the talker’s vocal tract.

Subject Classification: [43]70.30, [43]70.40, [43]70.70.
The photophone—physical design
Authors: Kleinman D. A. , Nelson D. F.
Published: October 2005

The physical design of the response-equalizing components of the acoustic transformer-coupled photophone is presented. Two possible equalizers for the absorption cell—a gas column and a loaded diaphragm— are discussed; one equalizer for the earpiece, consisting of a diaphragm and screen, is also discussed. The optimization, equalization, and physical realization of a direct-coupled photophone (one not containing an exponentially tapered tube acting as an acoustic transformer) is also presented. It is found that its response is poorer than the transformer-coupled photophone by 25 dB.

Subject Classification: [43]85.86, [43]85.40, [43]85.60.
Photophone performance
Authors: Nelson D. F. , Wecht K. W. , Kleinman D. A.
Published: October 2005

A photophone consisting of a light guiding fiber, an absorption cell containing charred cotton suspended in air, an exponentially tapered tube, and a standard earpiece volume has been made and tested. The pressure in the earpiece versus the frequency in the 300–3300-Hz telephone band for a given optical power input agrees well with the theory of the preceding paper. We conclude that the charred cotton suspended in air can be treated simply as light-absorbing air. Measurements were also made on a photophone which included an air column equalizer to resonate with the absorption cell in order to flatten the frequency response. The high-frequency (1500–3300 Hz) response was enhanced as expected thought not quite as much as predicted.

Subject Classification: [43]85.76, [43]85.40, [43]85.60.
Numerical solution of acoustic scattering problems at intermediate frequencies
Authors: Uncles R. J.
Published: October 2005

Integral equation methods of solving acoustic scattering problems at high frequencies require excessive computer storage and computer time to achieve solutions of adequate accuracy. In problems concerned with high-frequency scattering from simple surface shapes these difficulties result from the complexity of the scattered field on the scattering surface. A ’’structure reduction’’ approach is proposed which attempts to reduce these difficulties, and, as an example, the method is applied to plane-wave scattering from a rigid sphere at a nondimensional frequency of 10.

Subject Classification: [43]20.30, [43]20.15.
Gain of a linear array for spatially dependent signal coherence
Authors: Green Michael C.
Published: October 2005

The coherent or conventional gain of a linear array in an uncorrelated noise field is presented for various models of signal coherence decay with increasing sensor separation. For the case of linear decay, the coherent array gain is shown to approach a maximum of DL/s as the array length increases; where DL, the linear decay length, is defined as the vanishing point of the signal coherence and s is the adjacent sensor separation having some minimum value commensurate with the assumption of uncorrelated noise. For exponential decay of signal coherence a good approximation to the maximum coherent array gain is shown to be 2 DE/s for DE 〉〉s, where DE is the exponential decay length. However, for both linear and exponential decay it is shown that additional gain is achievable beyond the coherent gain limit using incoherent processing. Also a closed form expression is derived for the coherent gain of an array for Gaussian phase fluctuations which are correlated in a linear fashion.

Subject Classification: [43]60.20, [43]60.30.
Forward and backward masking in the presence of a continuous noise floor
Authors: Penner M. J. , Pavel Michael
Published: October 2005

Temporal masking of clicks by gated noise was investigated in forward and backward masking paradigms. In addition to the gated maskers, a continuous noise floor was present in some conditions. For three levels of continuous noise and for a condition in which there was no continuous noise, the threshold of the click was determined as a function of the temporal separation ΔT between the click and the noise (1?ΔT?100 msec). These data provide a new demonstration that the temporal masking effect due to the forward masker outlasts the temporal masking effect due to the backward masker.

Subject Classification: [43]65.58; [43]50.70.
Individual differences in pure-tone localization
Authors: Russell Graeme
Published: October 2005

The range of abilities of 85 subjects in localizing a 1-kHz pure tone in the horizontal plane is examined. Findings show that there is considerable variability in performance (?=47%, s=13), and that one subject performed at a markedly superior level (85% correct) to other subjects. It is suggested that the duplicity theory of pure-tone localization is inadequate to explain this superior performance, and other possible explanations are discussed.

Subject Classification: [43]65.62.
Temporary threshold shift and cochlear nerve fibers
Authors: Johnstone J. R.
Published: October 2005

The increased threshold of hearing following stimulation by a loud pure tone is greatest for test tones about half an octave above the frequency of the fatiguing tone. This effect may be related to the fact that many auditory neurones fire fastest for a stimulating tone which is rather lower in frequency than their characteristic frequency.

Subject Classification: [43]65.35, [43]65.64, [43]65.40.
Theoretical similarities of Rayleigh and Lamb modes of vibration
Authors: Pitts Leslie E. , Plona Thomas J. , Mayer Walter G.
Published: October 2005

Poles of the infinite plane-wave reflection coefficient are used to show a correspondence between Rayleigh and Lamb modes of vibration. It is demonstrated that a Rayleigh vibrational mode is a special type of Lamb mode of vibration. Further, it is shown that it should be expected that one vibrational mode for a thick plate should be similar to the theoretically predicted vibrational mode of an infinite half space, a Rayleigh mode. Thus, it is consistent to use a thick plate as an approximation to an infinite half space and expect results predicted by Rayleigh-wave analysis.

Subject Classification: [43]35.54; [43]40.24.
Discrimination and labeling of noise–buzz sequences with varying noise-lead times: An example of categorical perception
Authors: Miller James D. , Wier Craig C. , Pastore Richard E. , Kelly William J. , Dooling Robert J.
Published: October 2005

The onset of a noise [0.9–2.1 kHz, 55 dB SPL (A weighted)] preceded that of a buzz [100 Hz, 0.5–3.0 kHz, 70 db SPL (A weighted), 500 msec] by −10 to +80 msec and both terminated simultaneously. Eight adults discriminated among noise-lead times in an oddity task. In separate sessions, they labeled singly presented stimuli with either of the two responses: ’’no noise’’ or ’’noise.’’ The results are highly similar to those reported for the categorical perception of synthetic plosive consonants differing in voice-onset time. On the average, discrimination was best across a noise-lead-time boundary of about 16 msec, where labeling also shifted abruptly. These results and those of categorical perception, generally, are interpreted in terms of Weber’s law as applied to a single component within a stimulus complex. It is concluded that categorical perception of sounds is not unique to speech and suggested that it may be a general property of sensory behavior.

Subject Classification: [43]65.75; [43]70.30.
Inter- and intraspeaker variability in fundamental voice frequency
Authors: Atkinson James E.
Published: October 2005

A measure was obtained of the amounts of variability in fundamental voice frequency F0 in simple sentences produced by several adult male speakers. A comparison was made of intra- and interspeaker variability, and a detailed analysis was performed to determine the nature of this variability. Great variability was found between speakers, but more important was the finding that the intraspeaker variability was essentially as great as the interspeaker. This indicates that even for a single speaker’s utterances, considerable ’’noise’’ is present which can obscure the prosodic ’’signals.’’ The F0 variability involves seemingly random interleavings that affect the relative F0 values within an utterance, as well as, simple shifts in average F0 that affect the absolute F0 of the contour as a whole.

Subject Classification: [43]70.40, [43]70.70.
Identification of dichotic fusions
Authors: Repp Bruno H.
Published: October 2005

Seven synthetic syllables from a ’’place continuum’’ (/bae/–/dae/–gae/) were presented in all dichotic combinations for identification. These syllables fused completely, so that dichotic pairs were perceived as single stimuli. The response pattern could not easily be explained by an ’’auditory averaging’’ hypothesis. Rather, stimuli that were good instances of a category seemed to ’’dominate’’ stimuli that were closer to a category boundary. To account for this finding, a three-stage pattern recognition (’’prototype’’) model is proposed, according to which the information from the two ears is linearly combined after ’’multicategorical’’ processing, which follows auditory processing and precedes the final phonetic decision. Electronically mixed stimuli led to a response pattern that was similar to that for dichotic syllables (apart from some systematic deviations ascribed to peripheral masking), so that the same processes of central interaction seem to be involved. Average dichotic right-ear advantages of small magnitude were obtained for the dichotic fusions. They could not be reliably discriminated from binaural stimuli, and selective attention to one ear had little effect. With respect to the measurement of dichotic ear asymmetries, dichotic fusions offer certain methodological advantages over other dichotic stimuli. The problem of determining the ’’true’’ ear advantage is discussed.

Subject Classification: [43]70.30; [43]65.75.
Input impedance curves for the brass instruments
Authors: Backus John
Published: October 2005

Apparatus previously described [J. Acoust. Soc. Am. 56, 1266–1279 (1974)] to obtain input impedance curves for the woodwind instruments has been applied to the brass instruments. These curves show, for example, the importance of the bell and the mouthpiece in putting the resonance frequencies in their musically necessary places. The mouthpiece also has the important effect of increasing the input impedance presented to the player. The trumpet has input impedances at the various resonance frequencies ranging up to 1000 cgs acoustic ohms; trombones and French horns have about one-third as much. Trumpet mutes were investigated and found to behave as bandpass or high-pass filters which change the instrument’s radiated tone quality. The long-argued question about hand-stopping of horns was investigated; it was concluded that the effect of hand stopping is to lower the frequencies of all the modes.

Subject Classification: [43]75.40.
Analysis of diffraction in acoustic nonlinear parametric convolvers
Authors: White James M.
Published: October 2005

Acoustic parametric convolvers operate by spatially integrating a term produced by the nonlinear interaction of two propagating strain waves. The integrand will have an additional spatially dependent weighting factor and inaccuracies in the convolution output will result if the product term is not uniformly produced and summed. Under appropriate assumptions, the expansion of the acoustic field into an angular spectrum of plane waves is used to show that no erroneous weighting is introduced by diffraction, although diffraction does contribute a uniform loss to the convolver output. Under additional assumptions, the diffraction loss for the convolved output is shown to equal that which occurs in transmitting from one transducer to the other.

Subject Classification: [43]25.30, [43]25.35; [43]35.54; [43]60.30.
Eikonal approximation and the parabolic equation
Authors: Palmer D. R.
Published: October 2005

We discuss two aspects of the general problem of sound propagation in an ocean characterized by a range-dependent profile. We first consider a normal-mode formalism for describing a situation in which the eikonal approximation can be applied in the horizontal plane. The difficulty with this approach is shown to be an ordering in the geometric optics path-length parameter due to mode coupling. By example we indicate how this difficulty can be overcome. We then use the formalism to discuss the approximations which make up the parabolic equation method. The parabolic equation is derived by assuming the eikonal approximation in the horizontal plane and a degenerate spectrum approximation. The degeneracy approximation is reflected in a stationary phase approximation to an integral representation for the pressure field. We then derive improved equations by relaxing these assumptions. We relax the degeneracy assumption by considering an improved stationary-phase approximation and we relax the eikonal assumption by considering the ’’supereikonal’’ approximation.

Subject Classification: [43]30.20, [43]30.25, [43]30.50.
New approach to the analysis of monolithic crystal filters
Authors: Akcakaya E.
Published: October 2005

Using thickness-shear approximation theory and interpreting certain boundary conditions as torque or displacement drivers, a multiterminal component for each region of a definite multielectroded quartz structure (monolithic filter) is established. Repeating the same idea for shear-flexure approximation theory is complicated; however, more complete multiterminal component models are obtained for the regions. Such models make it possible to analyze monolithic quartz filters by ’’tearing and reconstruction technique’’ (i.e., by Diakoptics). The expressions for the insertion-loss function of a monolithic filter are derived by using both approximation theories, and computational results are given.

Subject Classification: [43]85.32; [43]40.65; [43]85.52.
Ultrasonic studies on the head oil of the North Atlantic pilot whale (Globicephala melaena melaena)
Authors: Blomberg Jonas , Jensen Bo Nordy
Published: October 2005

Head oil extracted from a sample of the melon was studied. Sound velocity and sound absorption data are presented. The data support the notion that some refraction of ultrasound will occur in the melon as the sound velocity of the head oil, comprising 80% of its weight, is lower than that of sea water. Deducing from these results the lens action of the melon seems not to be strong enough to explain the high directionality of the sound emitted in echolocation along, but suggests a cooperative refraction and reflection model. The data furthermore indicate a strong dependence on water temperature of the refractivity of the melon. An attempt is made to correlate the chemical composition with the sonic properties of the oil.

Subject Classification: [43]80.45, [43]80.50; [43]80.20.
Jet drive mechanisms in edge tones and organ pipes
Authors: Coltman John W.
Published: October 2005

Measurements of the phases of free jet waves relative to an acoustic excitation, and of the pattern and time phase of the sound pressure produced by the same jet impinging on an edge, provide a consistent model for Stage I frequencies of edge tones and of an organ pipe with identical geometry. Both systems are explained entirely in terms of volume displacement of air by the jet. During edge-tone oscillation, 180° of phase delay occur on the jet. Peak positive acoustic pressure on a given side of the edge occurs at the instant the jet profile crosses the edge and starts into that side. For the pipe, additional phase shifts occur that depend on the driving points for the jet current, the Q of the pipe, and the frequency of oscillation. Introduction of this additional phase shift yields an accurate prediction of the frequencies of a blown pipe and the blowing pressure at which mode jumps will occur.

Subject Classification: [43]75.60.
Resolution performance of Doppler ultrasound flowmeters
Authors: Griffith James M. , Brody William R. , Goodman Lester
Published: October 2005

Ultrasonic Doppler flowmeters can simultaneously obtain spatial and velocity distribution patterns of flow in a blood vessel. The factors fixing spatial and velocity resolution, however, must be determined if optimum utilization is to be realized. The parameters influencing spatial resolution have been described in the literature, but velocity resolution has received relatively little attention. This paper demonstrates analytically how optimum velocity resolution can be derived with a simple mathematical model and presents experimental data to verify theory. In addition, a ’’resolution product’’ is offered which characterizes pulsed Doppler flowmeters. This product shows explicitly the necessary compromise between position and velocity resolution for a given instrument.

Subject Classification: [43]28.60, [43]28.20; [43]80.70; [43]35.80.
Improved acoustic viscosimeter technique
Authors: Fisch M. R. , Moeller R. P. , Carome E. F.
Published: October 2005

An improved technique has been developed for studies of the shear viscosity of fluids. It utilizes an acoustic resonator as a four-terminal electrical device; the resonator’s amplitude response may be determined directly and simply related to the fluid’s viscosity. The use of this technique is discussed briefly and data obtained in several fluids is presented.

Subject Classification: [43]35.10, [43]35.68; [43]85.52.
Excitation, detection, and scattering of electroelastic surface waves via an integral equation approach
Authors: Sabbagh Harold A. , Krile Thomas F.
Published: October 2005

The problem of the excitation, detection, and scattering of electroelastic surface (Bleustein) waves is solved exactly by determining the charge distribution on the fingers of an interdigital transducer. The approach is to solve an integral equation, in the Fourier transform domain, that relates the charge density on the fingers to the electric potential of the fingers. The solution of the integral equation is accomplished by expanding the charge distribution in a series of pulses and then transforming the problem to a vector matrix,one which is readily handled by a computer. In this manner the charge distribution is determined for a variety of conditions.

Subject Classification: [43]35,54.
Uniform spinning cable as a vibration absorber
Authors: Vance O. L. , Woodward J. H.
Published: October 2005

This paper presents an analysis of the free vibrations of a disk–cable system spinning freely about a fixed axis through the disk center. Secondly, it is shown how the cable can be used as a vibration absorber to reduce the effect of torsional disturbances on a rotating system.

Subject Classification: [43]40.22, [43]40.70.