bluuebunny/crossref_metadata_2025 huggingface dataset:
Relations between auditory functions in impaired hearing
Authors: Festen J. M. , Plomp R.
Published: October 2005

Relations between auditory functions, as expressed by coefficients of correlation, were studied for a group of 22 sensorineurally hearing-impaired subjects with moderate losses. In addition to the audiogram, we measured frequency resolution, temporal resolution, and speech reception in quiet and in noise. Frequency resolution was derived from masking with comb-filtered noise and from the psychophysical tuning curve, for both paradigms in simultaneous and in nonsimultaneous masking. The critical ratio was also determined. Temporal resolution was determined with intensity-modulated noise and from backward and forward masking. All tests were performed at 1000 Hz. Correlations among tests were gathered in a matrix and subjected to a principal-components analysis. It turned out that tests on frequency resolution form a cluster, and are approximately independent of audiometric loss. Furthermore, hearing loss for speech in noise is closely allied to frequency resolution, whereas hearing loss for speech in quiet is governed by audiometric loss.
An improved Kirchhoff formula for reflection loss at a rough ocean surface at low grazing angles
Authors: Chapman D. M. F.
Published: October 2005

The calculation of specular reflection loss at a rough ocean surface is a time-consuming procedure if the boundary perturbation or mode-coupling methods are used. The simple Kirchhoff formula is often used as an estimate of reflection loss, but this is shown to severely underestimate the loss at small grazing angles. A formula is derived using the large correlation length limit of the boundary perturbation calculation, and is shown to be a more accurate estimate of the reflection loss at small grazing angles than the Kirchhoff formula. The new formula is identical with the Kirchhoff formula at large grazing angles.
No sharpening? A challenge for cochlear mechanics
Authors: de Boer E.
Published: October 2005

Recent data on mechanical movements of the basilar membrane (BM) suggest that the part played in cochlear physiology by a sharpening mechanism is much less important than hitherto has been thought. In an extreme view, one could dispense with a sharpening mechanism completely and assume that (near the threshold) hair-cell excitation is proportional to BM velocity, or a very simple linear transform of it. In the present paper the consequences of this idea are worked out. A theoretical cochlear movement pattern is constructed that shows the same frequency selectivity as an average reverse-correlation function of an auditory nerve fiber. This response is called a revcor-spectrumlike response. Cochlear mechanics is then simplified to a pure shortwave model. It is shown that, if the cochlea model should present a revcor-spectrumlike response, this can only be achieved when the resistance component of the BM impedance is negative over a part of the length of the cochlea. This result is refined in several respects, and it is shown that a model equipped with the right kind of BM impedance function can have a response of the required type. It remains difficult to conceive of a physiological mechanism that would cause the desired effect on the BM impedance.
Temporary threshold shifts produced by exposure to low-frequency noises
Authors: Mills John. H. , Osguthorpe J. David , Burdick C. K. , Patterson J. H. , Mozo B.
Published: October 2005

Groups of human subjects were exposed for 8 or 24 h to an octave-band noise centered at 63, 125, or 250 Hz. For a 24-h exposure at 84 dBA, temporary threshold shifts (TTS) increased for 8–12 h and then either decreased or remained constant. Although TTS was less than 20 dB, complete recovery for many of the subjects required as long as 48 h. Accordingly, the higher level exposure which was planned at 94 dBA for 24 h was reduced to 90 dBA for 8 h. For this condition TTS increased throughout the 8-h exposure. TTS from the 90-dBA noise for 8 h exceeded the TTS produced by the 84 dBA; however, recovery from the 24-h exposure required as long as 48 h, whereas recovery from the 8-h exposure required only 12–24 h. Thus the time required for recovery is determined in part by the duration of exposure. TTS was not always maximal 1/2 –1 oct above the band of noise, but was maximal in the frequency regions of better auditory sensitivity (350 to 750 Hz). For the 250-Hz condition, TTS increased about 1.5 dB per dB increase in noise level, whereas for the 63- and 125-Hz conditions TTS increased less than 1 dB per dB increase in noise level. More data are needed to specify the relation between TTS and the level of low-frequency noises.
Experimental investigation of the scattering effects of a sphere in a cylindrical resonant chamber
Authors: Barmatz M. , Allen J. L. , Gaspar M.
Published: October 2005

The resonance frequency, acoustic pressure, and quality factor for various longitudinal and transverse modes of a cylindrical chamber were measured as a function of sphere position along the chamber axis. In the limit of small spherical blockages, the shift in the plane-wave resonance frequency is proportional to the ratio of sample-to-chamber volumes, vs/v, as predicted by analytical models. The frequency shift measurements are compared to a phenomenological model based on the ratio of sample-to-chamber cross-sectional areas, as/a, and sample diameter to chamber length, ds/l. The frequency shift, Δf/f0, for plane waves is proportional to as/a, ds/l, and vs/v for ratios less than about 0.2, 0.1, and 0.013, respectively. Measurements for large values of these ratios for spherical and cylindrical blockages are in good agreement with the three-dimensional Green’s function theory of El-Raheb and Wagner [J. Acoust. Soc. Am. 72, 1046 (1982)]. An approximate analytical frequency shift expression is derived for the intermediate ratio region. The frequency shift measurements for modes containing a transverse propagation component were smaller in magnitude and different in shape than those of the plane-wave modes.
Acoustic scattering by elastic solid cylinders and spheres in viscous fluids
Authors: Lin Wen H. , Raptis A. C.
Published: October 2005

This paper deals with analytic studies and numerical results of the scattering of plane sound waves from an elastic circular cylinder and from an elastic sphere in a viscous fluid. The elastic properties of the cylinder and the sphere and the viscosity of the surrounding fluid are taken into account in the solution of the acoustic-scattering problems. The associated acoustic quantities, such as the acoustic-scattering patterns, the acoustic-radiation forces, and the acoustic attenuation, are first derived in closed forms and then evaluated numerically for a given set of material properties. Numerical results show that increasing fluid viscosity tends to increase the directionality of the angular distribution of the scattering patterns, especially in the forward direction. The acoustic-radiation force on the cylinder or on the sphere is in the direction of the incident wave and increases as the viscosity of the fluid increases. The plots of the acoustic-attenuation coefficients versus the dimensionless wavenumber of the incident sound wave reveal oscillatory phenomena, which are caused by the resonant vibrations of the cylinder or the sphere.
Propagation of finite-amplitude ultrasonic waves in air—I. Spherically diverging waves in the free field
Authors: Gallego-Juárez Juan A. , Gaete-Garretón Luis
Published: October 2005

An investigation of the free-field propagation in air of sinusoidal spherical waves of finite amplitude is described. It includes experiments made at 20.4 kHz and a theoretical interpretation using weak shock theory. The acoustic source used was a new high-power and highly directional ultrasonic transducer which is able to generate a nearly pure sinusoidal wave at sound pressure levels over 160 dB. The experiments were done in an anechoic chamber, using a cw mode. They consisted essentially of measuring the amplitude of the fundamental component of the wave and its first three harmonics for different source levels and at various distances along the axis of the source. In addition, oscillograms and directivity patterns were recorded. In general, the experimental data confirm the predictions of the theoretical model.
Sound power determination from surface intensity measurements on a vibrating cylinder
Authors: Kaemmer Norbert , Crocker Malcolm J.
Published: October 2005

The feasibility of using surface intensity measurements for the determination of sound power as a tool for noise source identification was studied with an experiment on a circular cylinder. This cylinder was an idealized model of a muffler shell of a heavy diesel truck. Two experiments were performed with the cylinder excited by an electromagnetic shaker. In the first one, the shaker was driven with a one-third octave band of white noise centered at 6300 Hz and in the second experiment it was driven with broadband white noise between 1000 and 5000 Hz. The sound power measurements were made in a reverberant room and the reverberant room method was used to provide a comparison with the sound power levels obtained from the surface intensity measurement. The acoustic surface intensity was computed from the cross-spectral density between the acoustic pressure and the normal surface velocity of the cylinder. An equation was developed to allow for inclusion of a correction for phase shifts that were caused by the instrumentation and by the finite distance between the microphone and the vibrating surface. The phase shift resulting from this distance was found to have a dominant effect in the higher frequency range and it was important to make these phase-shift corrections in order to obtain accurate measurements of sound power. After including these phase-shift corrections, reasonably good agreement was achieved between the sound power levels obtained from the surface intensity measurements and those from the reverberant room method.
Effects of frequency-modulated auditory tones on the voice fundamental frequency in humans
Authors: Sapir Shimon , McClean Michael D. , Luschei Erich S.
Published: October 2005

The sensitivity of audio-laryngeal reflex pathways to sinusoidal changes in the fundamental frequency of complex auditory tones (AF0) was assessed indirectly in three young adult human subjects. The subjects sustained phonation at constant voice fundamental frequency (VF0) and voice intensity while listening to a sawtooth tone whose AF0 varied over time in a sinusoidal fashion (rates=5–13 Hz). The subjects phonated at a low voice intensity so that the intensity of the auditory tone (80–85 dB SL) completely masked their voice. Using computer signal averaging and Fourier analysis techniques it was found that the sinusoidally modulated AF0 induced similar modulations in the VF0 signal. The VF0 modulations were extremely small in amplitude and showed large phase shifts relative to the auditory input. These findings are discussed in relation to the role of auditory feedback in phonatory control.
Enhanced discriminability at the phonetic boundaries for the place feature in macaques
Authors: Kuhl Patricia K. , Padden Denise M.
Published: October 2005

Discrimination of speech-sound pairs drawn from a computer-generated continuum in which syllables varied along the place of articulation phonetic feature (/b, d, g/) was tested with macaques. The acoustic feature that was varied along the two-formant 15-step continuum was the starting frequency of the second-formant transition. Discrimination of stimulus pairs separated by two steps was tested along the entire continuum in a same–different task. Results demonstrated that peaks in the discrimination functions occur for macaques at the ‘‘phonetic boundaries’’ which separate the /b–d/ and /d–g/ categories for human listeners. The data support two conclusions. First, although current theoretical accounts of place perception by human adults suggest that isolated second-formant transitions are ‘‘secondary’’ cues, learned by association with primary cues, the animal data are more capatible with the notion that second-formant transitions are sufficient to allow the appropriate partitioning of a place continuum in the absence of associative pairing with other more complex cues. Second, we discuss two potential roles played by audition in the evolution of the acoustics of language. One is that audition provided a set of ‘‘natural psychophysical boundaries,’’ based on rather simple acoustic properties, which guided the selection of the phonetic repertoire but did not solely determine it; the other is that audition provided a set of rules for the formation of ‘‘natural classes’’ of sound and that phonetic units met those criteria. The data provided in this experiment provide support for the former. Experiments that could more clearly differentiate the two hypotheses are described.
Discrete lung sounds: Crackles (rales) as stress–relaxation quadrupoles
Authors: Fredberg Jeffrey J. , Holford Stephen K.
Published: October 2005

We modeled discrete emission of sound from lung parenchyma as a point source in an ideal medium. The point source, a quadrupole, represents the stress anomaly in lung parenchyma in the neighborhood of a collapsed airway, and its time course when the airway opens. The dynamics of the airway opening event are characterized by a single time constant. The ideal medium, lung parenchyma, was modeled as a homogeneous linearly elastic lossless nondispersive continuum of infinite extent undergoing infinitesimal strains. Depsite its simplicity, this elementary model leads to predictions of crackle waveforms, spectral densities, and spatial intensity distributions which are consistent with observations. In particular, the model predicts changes of waveform shape and polarity with observation position relative to the source, dramatic influences of transduction processes, and successive increases in zero crossing time intervals.
Maintaining precision calibrations with optimal copper spheres
Authors: Foote Kenneth G.
Published: October 2005

Effects of variations in quantities influencing the backscattering cross sections of solid elastic spheres are studied through a particular case. This is that of the 60-mm-diam copper sphere, which is being used worldwide to calibrate the 38-kHz echo sounders instrumental in fisheries surveying. Derived dependences of the backscattering cross section include those characterizing the sphere, immersion medium, and equipment. Some of the dependences are sufficiently weak to permit their neglect in assigning the calibration value of the backscattering cross section, while others must be considered. In every case the dependences are calculable; given measurement of the calibration conditions, necessary corrections to the backscattering cross section can be determined and applied with maintenance of 0.1-dB accuracy. The wider use of copper spheres in acoustic calibrations, as in the radiation force method, is advocated. The practical use of optimal copper spheres in calibrating echo sounders and echo integrators is treated in detail in an appendix.
Comments on ‘‘Noise-induced shifts in the pitch of pure and complex tones’’ [J. Acoust. Soc. Am. 7
, 1661–1668 (1981)]
Authors: Terhardt Ernst
Published: October 2005

Houtsma concludes from his experimental data spectral pitch and virtual pitch are dependent on two basically different mechanisms. The purpose of these comments is to point out some reservations about his conclusions.
Enlargement of the supraglottal cavity and its relation to stop consonant voicing
Authors: Westbury John R.
Published: October 2005

Measurements were made of sagittal plane movements of the larynx, soft palate, and portions of the tongue, from a high-speed cinefluorographic film of utterances produced by one adult male speaker of American English. These measures were then used to approximate the temporal variations in supraglottal cavity volume during the closures of voiced and voiceless stop consonants. All data were subsequently related to a synchronous acoustic recording of the utterances. Instances of /p,t,k/ were always accompanied by silent closures, and sometimes accompanied by decreases in supraglottal volume. In contrast, instances of /b,d,g/ were always accompanied both by significant intervals of vocal fold vibration during closure, and relatively large increases in supraglottal volume. However, the magnitudes of volume increments during the voiced stops, and the means by which those increments were achieved, differed considerably across place of articulation and phonetic environment. These results are discussed in the context of a well-known model of the breath-stream control mechanism, and their relevance for a general theory of speech motor control is considered.
Improved resonance technique for materials characterization
Authors: Madigosky Walter M. , Lee Gilbert F.
Published: October 2005

An improved resonance apparatus for materials characterization is described. The apparatus accurately determines the propagation constants of an extensional acoustic wave by exciting a bar of material at one end with a noise source, while the other end is allowed to move freely. Miniature accelerometers measure the acceleration at two locations and their output signals are analyzed by a dual channel FFT spectrum analyzer. At certain frequencies, the acceleration ratio goes through resonant peaks whose amplitudes and frequencies are related to the Young’s moduli and loss factors of the material. The apparatus is capable of measuring the acceleration ratio over a frequency range of 25 Hz to 20 kHz. As illustrations of the technique, Young’s modulus and loss factor were determined on a viscoelastic material; polyurethane (over a temperature range −13.4° to 81 °C) and on two metal matrix composite materials: a silicon carbide–aluminum and a graphite–aluminum. The apparatus was found to be a fast and reliable method to determine dynamic constants.
Modeling and applications of straight-through resonators
Authors: Thawani Prakash T. , Jayaraman Krishnamurthy
Published: October 2005

Straight-through concentric resonators have been modeled by coupling the acoustic wave propagation through the inner perforated pipe and the outer cavity by means of the radial particle velocity through the perforate holes. The decoupled equations of wave propagation are solved using the boundary conditions in the cavity resulting in a two-by-two transfer matrix. In this study the decoupling procedure was used for deriving the transfer matrix for a partially perforated straight-through resonator. This transfer matrix was used for predicting the transmission loss for some typical resonator configurations. Experimental and analytical results of several resonator configurations are presented showing good agreement.
Progressive phase trends in multi-degree-of-freedom systems
Authors: Lyon Richard H.
Published: October 2005

The relative phase of the response of a dynamical system to its excitation has been largely ignored in problems dealing with noise response of such systems. This is because mean-square amplitude functions are able to predict many of the quantitites that one is interested in such as crack growth, noise radiation, and clearance impact probabilities without concern for phase. But phase has an essential role in other cases, such as phase coherence of vibration fields, or the design of filters to ‘‘dereverberate’’ a received signal. This paper describes some early results of the analysis of phase response of multi-degree-of-freedom systems, using ideas that are closely related to statistical energy analysis, until now, used exclusively for the kinds of problems listed above that tend to ignore phase. The present results show good agreement between simple theory and experiments, but more importantly, they suggest directions for further work that should have significant payoff in the future.
An analysis of community complaints to noise
Authors: Luz George A. , Raspet Richard , Schomer Paul D.
Published: October 2005

Noise complaints received Army-wide for a one-year period were analyzed (a) to determine the relationship between the nature of the complaint and the type of noise and (b) to determine the relationship between complaints and the day–night level (DNL). For blast noise, 77% of complaints mentioned vibration or physical damage or both, thus confirming the validity of the C-weighted DNL as a better measure of blast noise than the A-weighted DNL. The relationship between DNL and complaints, however, was a very weak one. Instead, the data confirmed an independent finding of a recent study of Air Force noise complaints—that complaints are generated by unusual rather than typical noise levels. Since a valid measure of community response to noise should be functionally relatable to the noise dose, complaints do not appear to be a good measure of the community response. To deal with the wide variability in the emotional tone of the complaints a psychological model was developed and tested. The implications of this model for how an airport or Army base should deal with complaints are discussed.
Further studies of auditory profile analysis
Authors: Green David M. , Kidd Gerald
Published: October 2005

The discrimination of a change in the intensity of a component or components of a multitone complex is reported as a function of a number of experimental variables. In one experiment, changes in the shape of the spectrum were explored to determine which kinds of changes are more easily detected. Although different signal spectra produced different thresholds, the change in a single component produced the lowest threshold on an energy basis. Various binaural conditions were tested to determine if the shape or profile of the stimulus could be supplied by the ear opposite the one in which the signal was presented. Conditions where spectral contrasts were available to both ears simultaneously (diotic conditions) were much more sensitive than conditions where the spectral contrasts occurred for opposite ears (dichotic conditions). Finally, the level of the component at the signal frequency was varied relative to the other, equal amplitude, components to form a ‘‘pedestal’’ upon which the signal was added. Detection of the signal was roughly the same for pedestal levels within about ±12 dB of the background except for conditions where masking was apparent.
A central spectrum model: A synthesis of auditory-nerve timing and place cues in monaural communication of frequency spectrum
Authors: Srulovicz P. , Goldstein J. L.
Published: October 2005

A probabilistic psychophysical model for monaural communication from the auditory nerve to the brain is given in the form of a tonotopic display of stimulus spectrum, termed central spectrum. The model builds upon prior research demonstrating the potential of neural timing cues from the auditory nerve for conveying information on complex spectra, and was designed to meet the quantified demands of the psychophysics of frequency measurement. The central spectrum magnitude at each frequency is determined by the response of the auditory-nerve fiber with characteristic frequency matching that frequency. An interval histogram from each fiber is passed through a filter matched to the characteristic frequency of the fiber. This output versus characteristic frequency defines the central spectrum. Detailed analysis demonstrates that efficient probabilistic processing of the central spectrum describes known psychophysical properties of frequency measurement in discrimination and periodicity pitch experiments. Psychophysical models based upon the central spectrum model followed by optimum probabilistic pattern recognition are potentially relevant for predicting human communication limits in response to arbitrary sounds of speech and music.
Vibrotacile masking of Pacinian and non-Pacinian channels
Authors: Hamer Russell D. , Verrillo Ronald T. , Zwislocki Jozef J.
Published: October 2005

Vibrotactile masking functions were determined using sinusoidal and noise maskers. Results were nearly identical within the Pacinian (P) and non-Pacinian (NP) channels. At low masker SLs there was a substantial amount of negative masking which proved not be an artifact of stimulus definition. The critical parameters for successful prediction of the data were a peripheral threshold and internal Gaussian noise. Threshold shifts in cross-channel stimulation can be attributed to the masker exceeding the detection threshold of the signal channel.
Computerized measurement of tongue dorsum movements with pulsed-echo ultrasound
Authors: Keller Eric , Ostry David J.
Published: October 2005

A computerized system for the measurement of tongue dorsum movements with pulsed echo ultrasound is described. The presentation focuses on technical and methodological considerations in the on-line acquisition of vertical tongue movement information, its digital processing and display. Problems associated with transducer placement, peak detection, data averaging, and curve fitting are considered, and validation procedures based on x ray and indicators of measurement reliability are reported. The discussion centers on advantages and disadvantages of the technique and its applications.
Spectral theory of sound propagation in an ocean channel with weakly sloping bottom
Authors: Kamel A. , Felsen L. B.
Published: October 2005

Spectral representations based on the theory of characteristic Green’s functions (resolvents) have been used effectively for studying sound propagation in a coordinate separable ocean environment. Such representations are here generalized to accommodate weak nonseparability as represented by a homogeneous water channel separated from a homogeneous sediment by a gradually and monotonically sloping bottom. The generalization involves the use of adiabatic invariants for the spectral integration variable and of symmetrizing factors in order to insure that the Green’s function, so expressed, reduces by residue calculus to the conventional adiabatic trapped mode expansion whenever that is valid. However, subject to ignoring coupling between the adiabatic modes, the generalized Green’s function contains all of the spectral information (discrete and continuous) for upslope propagation from a source to arbitrary observation points in the water or the bottom, and it can be used to derive ray, hybrid ray-mode, and other formulations in this configuration. Numerical evaluation of the spectral integral and comparison with results obtained independently by the parabolic equation algorithm have confirmed its validity for a typical range of observer locations. Asymptotic considerations have been employed to clarify the mechanism of adiabatic mode transition from trapped to radiating in terms of lateral and leaky waves, and to reduce the spectral integral to a simpler canonical transition function similar to those of Pierce [J. Acoust. Soc. Am. 72, 523–531 (1982)] and of Arnold and Felsen [J. Acoust. Soc. Am. 73, xxx–xxx (1983)] which were derived by entirely different methods.
Doubly asymptotic approximations for vibration analysis of submerged structures
Authors: Geers Thomas L. , Felippa Carlos A.
Published: October 2005

Doubly Asymptotic Approximations (DAAs) are differential equations for boundary-element analysis of the interaction between a complex structure and a surrounding infinite medium. In this paper, the use of first- and second-order DAAs for steady-state vibration analysis of submerged structures is examined. First, the governing discrete-element equations for the general problem are set down and discussed. Then the accuracy of three DAA forms is studied through the generation of numerical results for a submerged spherical shell. Although the first-order DAA is found to be inadequate, the two second-order forms show considerable promise.
Flexural disk hydrophones using polyvinylidene fluoride (PVDF) piezoelectric film: Desensitization with increasing hydrostatic pressure
Authors: Holden A. J. , Parsons A. D. , Wilson A. E. J.
Published: October 2005

A piezoelectric polymer polyvinylidene fluoride hydrophone was developed which shows significant desensitization as the hydrostatic pressure is increased from 0 to 0.62 MPa. We show theoretically and experimentally that this is due to the boundary of the disk changing from ‘‘simply supported’’ to ‘‘clamped.’’ We investigate ways in which this problem can be overcome using a profiled disk with rounded supports.
Comments on ‘‘Doppler time mapping’’ [J. Acoust. Soc. Am. 7
3, 1863–1864 (1983)]
Authors: Ricker D. W.
Published: October 2005

The subject paper presents an algorithm which compensates for transit time errors due to motion induced wave-front distortion which arises from motion normal to the line of sight between a projector and scatterer. This error is small in most practical applications and may, if necessary, be compensated for by a redefinition of the line of sight vector utilized by Ricker [D. W. Ricker, ‘‘Echo waveform synthesis in a rapidly varying geometry,’’ J. Acoust. Soc. Am. 72, 1321–1323 (1982)].
Optimizing the performance of a quantizer
Authors: Struzinski William A.
Published: October 2005

In a previous paper [W. A. Struzinski, IEEE Trans. Acoust., Speech, Signal Process. ASSP-30 (4), 668–671 (1982)], a mathematical model was developed to compute the ORing loss for a system composed of quantizers followed by an ORing device and an accumulator. The quantizer investigated was an eight level (3-bit) device spanning from the noise-only mean, m0 to m0+2σ. The subject paper examines different spans for the same 3-bit quantizer to determine the span that yields the optimal performance. It is determined that the optimal performance is obtained when the quantizer spans the range m0 to m0+3σ. The ORing loss and the input signal-to-noise ratio requirements for the ORing device are computed for this quantizer. Then, these results are compared with those for the quantizer spanning the range m0 to m0+2σ. Based on this comparison, it is concluded that the performance difference increases with a decrease in the false alarm probability and the number of samples in the accumulator and with an increase in the number of channels ORed.
The temperature dependency of neural and hair cell responses evoked by high frequencies
Authors: Brown M. Christian , Smith D. Ian , Nuttall Alfred L.
Published: October 2005

A fine thermocouple, placed on the round window of the guinea pig cochlea, was used to measure temperature and electrical potentials. In acute experiments, rectal temperature was held constant at 38 °C while cochlear temperature was varied between 38 °C and 31.5 °C. Cochlear cooling to 36 °C caused elevated thresholds for the compound action potential (CAP) in response to tone bursts with frequencies above 24 kHz. CAP latencies increased for all frequencies tested (2 to 40 kHz). Cooling to lower temperatures produced larger latency increases and greater threshold shifts which extended to CAPs evoked by frequencies as low as 16 kHz. These CAP changes were fully reversible after a cochlear temperature of 38 °C was restored. In an attempt to create more uniform cooling of the cochlea, experiments were also conducted with round window thermo couples chronically implanted in guinea pigs. After cooling the entire anesthetized animal to 36 °C, CAP thresholds were again elevated only for frequencies above 24 kHz. In other acute experiments, extracellular dc receptor potentials were recorded from the organ of Corti with micropipettes. Cooling caused a decreased sensitivity to tones at the characteristic frequency of the recording location (20 kHz) and had less effect on responses to lower frequencies. The receptor potential usually recovered after rewarming the cochlea. These data emphasize that temperature is an important parameter when electrophysiological measurements are being made. They also suggest an explanation for the reported discrepancy between behavioral and electrophysiological thresholds at high frequencies.
Comparison of click responses of primary auditory fibers with minimum-phase predictions
Authors: Geisler C. Daniel , Sinex Donal G.
Published: October 2005

Minimum-phase impulse responses were constructed from the frequency threshold-response curves of primary auditory fibers in the anesthetized cat. These impulse responses had many of the same characteristics as the experimental click responses. The two types of responses had similar inter-peak intervals as well as similar (±1.5 ms) latencies to the principal mode and similar (±1.0 ms) intervals from response onset to the principal mode.
Acoustic streaming, dimensional analysis of nonlinearities, and tone hole mutual interactions in woodwinds
Authors: Keefe Douglas H.
Published: October 2005

The transmission line description of a woodwind assumes that the linearized wave equation of acoustics is accurate, and that the woodwind tone holes are independently represented in the transmission line by shunt and series impedances. Additional interactions exist between the tone holes when the interhole separation becomes small relative to the main bore diameter. Internal hole interactions, expressed via the main bore evanescent modes, are most important in woodwinds with large diameter holes such as the saxophone and Boehm flute. Tone holes interact externally to a lesser degree when the radiated sound field from one hole modifies the near field of neighboring holes. Acoustic streaming and convective nonlinearities are components of the sound field in woodwinds under playing conditions. The presence of the nonlinear sound field is correlated with changes in timbre and the stability of oscillation, and is more pronounced for tone holes whose height is much smaller than the hole diameter. Dimensional analysis, using the Reynolds number associated with the steady streaming velocity and the Strouhal number associated with the strength of the convective nonlinearity along the streamlines near the tone hole edges, is used to estimate the importance of sound field nonlinearities in various woodwinds. Observation and dimensional analysis are in agreement that nonlinearities are most important for the low register tones of a woodwind. The tone hole geometries of woodwind families are tabulated and discussed.
The optimization of electronic precision in ultrasonic velocity measurements: A comparison of the time interval averaging and sing around methods
Authors: Aindow J. D. , Chivers R. C.
Published: October 2005

Measurement of ultrasonic velocity is of importance in fluids for physical chemistry and in solids for both fundamental and applied investigations. In fluids, the sing around technique is most widely advocated as a single measurement principle with calculated high precision. Time interval averaging has also been used for some time, but its potential has been greatly increased by recent developments in instrumentation. The purpose of this paper is to define a criterion, based upon confirmatory experimental evidence, for the preferential use of one technique or the other in a given experimental situation.
Crosscorrelation functions for directionally distributed energy fields
Authors: Barnard Thomas E.
Published: October 2005

This paper presents the time-lag probability density function between two sensor outputs for several types of directionally distributed energy fields. The convolution of this density function with the inverse Fourier transform of an energy field’s frequency power density spectrum is the crosscorrelation function between the two sensor outputs.
Turbulence effects on acoustic wave propagation over a smooth surface
Authors: Clifford Steven F. , Lataitis Richard J.
Published: October 2005

A rigorous, mathematical treatment describing refractive turbulence effects on the mean-square pressure p̄2 of an isotropic acoustic source radiating above a smooth boundary is presented. The result is energy conserving, is general enough to allow the insertion of an arbitrary refractive-index correlation function, and does not require the ad hoc introduction of arbitrary parameters. This result is compared and contrasted with earlier work by other authors.
Modeling of long-range acoustic transmissions through cyclonic and anticyclonic eddies
Authors: Itzikowitz S. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

An approximate ray-acoustic model is used to obtain general information and overall results for long-range sound propagation through mesoscale cyclonic and anticyclonic eddies of arbitrary size and strength. Two-dimensional ray approximations are employed, and currents and horizontal sound-speed variations are averaged along approximate paths within an eddy. Eddy-induced per-ray travel-time changes are shown to depend nearly linearly on current strength and piecewise linearly on eddy size. For transmission ranges of about 1000 km, the presence of the eddy may cause per-ray travel time to increase (or decrease) by nearly 200 ms in the cyclonic (or anticyclonic) case. Variations in eddy current strength alone are shown to cause changes of about 100 ms in per-ray travel time. Currents may cause travel-time changes which are as much as those due to sound-speed variations close to eddy edge, and which are as much as 15% of sound-speed effects elsewhere. This suggests that in an acoustic tomography procedure, a corresponding percentage error in predicted sound-speed variations may arise by neglecting currents. In some total-field examples, it is shown that variations in eddy size and strength, and in source and receiver location, can cause an increase of about 5 dB or decrease of over 10 dB in transmission loss, relative to the case when the eddy is absent. Further, it is shown that explicit inclusion of currents alone may cause an increase or decrease of over 10 dB in transmission loss.
Free volume of sodium chloride solutions in water–dimethyl formamide mixtures from ultrasonic velocity
Authors: Pillai S. O. , Natarajan S. , Palanisamy P. K.
Published: October 2005

Free volume of sodium chloride solutions in water–dimethyl formamide mixtures have been evaluated using ultrasonic velocities from new formulas obtained by dimensional analysis. The results have been discussed in the light of existing theories.
Acoustic resonance scattering by a penetrable cylinder
Authors: Brill Donald , Gaunaurd G. C.
Published: October 2005

Although sound scattering by submerged elastic cylinders has been the subject of many papers, it was only recently that this and similar problems have been examined in the light of the resonance scattering theory (RST). Crucial experiments have been performed recently at Le Havre, France, in which the modal resonances contained within the cylinder’s backscattering cross section were isolated by means of a background subtraction, experimentally accomplished by a clever time-gating technique. In the present paper we generate a variety of tailor-made calculations and graphical displays required to thoroughly examine those experiments in the light of the RST. For the same cylinder, liquids, and frequency ranges of interest we have produced many spectral graphs displaying all the modal resonances that combine with the modal backgrounds to produce the observed and/or predicted cross sections. Our calculations: (a) display the whispering gallery and Rayleigh-type poles in the complex frequency plane and show their connection with the target resonances they generate, which manifest themselves as circumferential waves around the target, (b) explain quantitatively why some of the modal resonances were missed in the experiment, (c) establish comparisons between predicted and observed monostatic and bistatic form functions (or cross sections) in a direct scattering mode of operation, and (d) show ways to improve both the monostatic and bistatic measurements performed at Le Havre, paving the way toward the solution of inverse scattering situations. Within the limits of simple shapes and compositions, and within the controlled environment of the laboratory, these favorable comparisons have satisfactorily validated many of the predictions of the RST in the field of acoustics.
Resonance reflection of acoustic waves by a perforated bilaminar rubber coating model
Authors: Jackins P. D. , Gaunaurd G. C.
Published: October 2005

We construct the prediction of the resonance scattering theory (RST) for the reflection of sound waves by a bilaminar rubber configuration separating two dissimilar semi-infinite acoustic media. The layers are further assumed to contain distributions of spherical air-filled perforations, of various concentrations in each layer, whose behavior is governed by a simple, static, ‘‘effective parameter’’ model. We compare the direct scattering prediction of the RST to that of the exact solution in order to show the usefulness of the RST to yield clear physical interpretations of complex phenomena. The casting of the direct scattering solution in ‘‘RST-form’’ also provides a systematic method to solve the inverse scattering problem for the composition of the bilaminar rubber configuration. The ‘‘response surface’’ and response curves of the returned echoes are shown to contain certain modulation effects, described in the text, that actually characterize the material composition of each of the layers making up the coating model. The process disentangles which resonance feature present in the reflection coefficient is caused by which one of the interacting layers. In particular, we can separate and identify the impedances and the respective thickness-to-speed ratios (transit times) of each of the layers, and if additionally, either the thicknesses or the speeds are known, then, the process determines the other one and also the layer densities all from the resonances in the remotely sensed acoustic reflections.
Physical characteristics of the lips underlying vowel lipreading performance
Authors: Montgomery Allen A. , Jackson Pamela L.
Published: October 2005

To evaluate the relationship between physical characteristics of the lips during vowel production and vowel lipreading confusions, four female talkers were videotaped producing 15 American English vowels and diphthongs in an /h/-V-/g/ context. Ten normal-hearing adults identified the stimuli through lipreading. Three analyses were performed. First, using confusion matrices for individual and pooled talkers, the stimuli were located in a two-dimensional space using multidimensional scaling. The ten monophthongs revealed a clear lip spreading/rounding dimension and a tongue height dimension, and while diphthongs also showed influence of lip rounding, more variability on the tongue height dimension was apparent. Second, tracings were made of the talkers’ lips on a single videotape field representing the maximum opening or constriction for each of the 40 monophthong tokens (ten vowels×four talkers), and six physical measurements of the tokens were derived as descriptors of the vowel nuclei. Third, difference scores and other measures of physical pairwise similarity were used as predictors of two ways of representing the vowel lipreading confusions in a multiple regression paradigm. Results indicated that the physical measures were moderately successful as predictors of vowel perception (accounting for approximately 50% of the variance in the perceptual distance measure), although considerable differences in the strength of the prediction occurred among talkers.
Children’s perception of speech in reverberation
Authors: Neuman Arlene C. , Hochberg Irving
Published: October 2005

Recordings of nonsense syllables (VCV construction) were presented to groups of children aged 5, 7, 9, 11, and 13 years and young adults under monaural (reverberation time=0.6 s) and binaural (reverberation times=0, 0.4, and 0.6 s) conditions of reverberation. Phoneme identification performance was affected by age, reverberation, and mode of presentation (monaural versus binaural). The major findings were (1) phoneme identification scores in reverberant conditions improved with increasing age and decreased with increased reverberation time; (2) children’s performance in reverberant conditions did not reach asymptote until age 13; (3) binaural performance was consistently better than monaural performance for all age groups, with 5-year-olds showing the largest binaural advantage.
Ground couplings and measurement frequency ranges of vibration transducers
Authors: Omata Sadao
Published: October 2005

Vibration transducers do not faithfully follow the ground motion at high frequencies, since a resonant system is formed by the weight of the vibration transducer and the contact compliance of a placing point. Particularly, the contact resonances cause errors in measurement and place restrictions on the measurement frequency range. The characteristics of the effect of ground coupling depend on the type and condition of the ground surface and the method of planting the transducer. This paper examines the characteristics of the frequency response of the vibration transducer placed on the ground and provides the optimum relationships between the base area and the weight of the transducer for decreasing the effect of ground coupling under all conditions. The relationships are represented in the figures for the user’s convenience. When the vibration transducers designed to satisfy the relationship proposed here are employed for the measurement of the ground vibration, it is shown that the errors in measurement caused by the ground coupling decrease considerably. As compared with the old vibration transducers the measurement frequency ranges are markedly spread out.
Log-periodic acoustic lens–acoustic filter plate study. II
Authors: Sternberg Robert L. , Anderson Warren A. , Dickson Owen P. , Ilson Howard F. , Marchese Peter S.
Published: October 2005

Graphical experimental data in the form of passive receiving scanning beam patterns is presented for several high resolution acoustic lens–acoustic filter plate combinations. They show the comparative properties of various types of flat and curved filter plates when used in such acoustic antennas. Experimental data relating the achieved frequency-independent constant beamwidth of the several lens–filter plate combinations to the governing parameters of the filter plates are summarized for empirical design purposes. The basic experiments reported were conducted over the frequency range from 25 to 1000 kHz but the results can be scaled to any frequency range of the corresponding scaled width. As a receiving antenna, the acoustic lens–acoustic filter plate device eliminates the distortion imposed on the spectral content of a received multifrequency signal as a function of angle-off-boresight which is inherent in the use of conventional variable beamwidth directional receiving antennas.
Experimental constant beamwidth transducer
Authors: Van Buren A. L. , Luker L. Dwight , Jevnager M. D. , Tims A. C.
Published: October 2005

The theory of a broadband constant beamwidth transducer (CBT) which is based on Legendre function shading of a spherical cap was described in a previous report [P. H. Rogers and A. L. Van Buren, J. Acoust. Soc. Am. 64, 38–43 (1978)]. Theoretical calculations showed the CBT to have uniform acoustic loading, extremely low side lobes, virtually no nearfield, an essentially constant beam pattern for all frequencies above a certain cutoff frequency, and a flat transmitting current response over a broadband for piezoelectric drive. In this paper we present experimental results obtained for a prototype CBT based on fifth-order Legendre function shading. The transducer is a spherical cap with a diameter of 30.5 cm and a total cap angle of 50°. Measurements on the CBT showed it to possess very low side lobes and a nearly constant beamwidth over the frequency range from 20 to 140 kHz for ambient pressures up to 3.4 MPa. We also present formulas useful in the design of a CBT which is to be used as a transmitter and/or receiver. The formulas involve simple algebraic and trigonometric expressions which can be readily evaluated using a pocket calculator.