bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression and the dynamic range of hearing
Authors: Plack Christopher J. , Viemeister Neal F.
Published: October 2005

The results from experiments that have examined intensity discrimination in the presence of notched noise indicate that spread of excitation is not necessary for the auditory system to maintain a large dynamic range. In those experiments the notched noise and the pedestal were simultaneously present. It is possible, therefore, that the notched noise suppressed the pedestal, and increased the dynamic range by reducing the excitation level [A. R. Palmer and E. F. Evans, Hear. Res. 7, 305–323 (1982)]. In the experiment described here, spread of excitation was masked nonsimultaneously in order to avoid suppressive effects. The brief sinusoidal pedestal was presented in a 13-ms gap between two bursts of a masking complex. The masking complex consisted of two sinusoids at frequencies of 0.8fc and 1.2fc (where fc was the pedestal frequency), each having a level either the same as, or 10 dB below the pedestal level, and a notched noise with a spectrum level 40 dB below the level of the sinusoids. Detection thresholds were measured to ensure that the complex was effective in masking spread of excitation. Weber fractions were measured at two pedestal frequencies, 1 and 4 kHz, and at eight pedestal levels at each frequency, covering a range of 70 dB. The results indicate that, although the masking complex raised the Weber fraction by up to 10 dB in some conditions, performance was no worse at high levels than at medium or low levels. This suggests that the auditory system can maintain a large dynamic range in the absence of suppression and spread of excitation.
Longitudinal waves in homogeneous anisotropic cylindrical bars immersed in fluid
Authors: Dayal Vinay
Published: October 2005

The propagation of a longitudinal wave in an anisotropic cylindrical bar immersed in water is considered. Energy is leaked into the surrounding fluid in the form of traveling waves, and this leakage determines the amplitude of the signal in the rod. This aspect is important in nondestructive evaluation of composite rods. The governing equation of the longitudinal waves traveling in the rod is obtained and is solved numerically to obtain the dispersion curves and the attenuation, which is due to the energy leaked into the fluid. Results are presented for rods of five different materials.
Wave propagation theory in anisotropic periodically layered fluid-saturated porous media
Authors: Sun F. , Banks-Lee P. , Peng H.
Published: October 2005

A study is made of harmonic plane-wave propagation through an anisotropic, periodically layered, fluid-saturated, porous medium. Biot’s theory is used to describe the constitutive equations of a fluid-saturated porous solid. Employing the idea of introducing fundamental elasticity tensors, the field equations governing the wave propagation are derived in terms of first-order matrix ordinary differential equations. Propagator matrix formulation is adopted to treat the periodically layered property. Within this framework, the inhomogeneous medium is treated by dividing it into homogeneous layers. This technique is acceptable provided the coefficient matrix of ordinary differential equations consists of piecewise constants. Also, within each layer, the general case of anisotropic, fluid-saturated, porous materials can be considered. Based on this approach, a numerical model was developed and results are presented for a fluid-saturated, fabric material.
Measurement of broadband intrinsic ultrasonic attenuation and dispersion in solids with laser techniques
Authors: Pouet Bruno F. , Rasolofosaon N. J. P.
Published: October 2005

In this paper, a methodology is presented for measuring the intrinsic ultrasonic attenuation and dispersion on a broad frequency band (nearly 6 octaves) in polymers (PVC, PE, PMMA, PC, PP, POM, nylon) using laser ultrasonic techniques. Aperture-diffraction effects are completely avoided by using point emission and detection. The intrinsic character of these measurements is unambiguously demonstrated by the independence of the results with respect to sample length. Furthermore, the broad frequency-band nature of the measurements is used to corroborate Kramers–Kronig relations.
An analysis of the three-dimensional sound field in a penetrable wedge with a stratified fluid or elastic basement
Authors: Deane G. B. , Buckingham M. J.
Published: October 2005

A new analytical solution for the three-dimensional sound field due to an harmonic, point source in a broad class of penetrable wedges is presented. The only restriction on the wedge basement is that it be horizontally stratified. Thus realistic models of the ocean floor, such as a fluid or elastic sediment layer overlying a hard elastic substrate, can be handled. The wave-theoretic solution is based on the method of source images in conjunction with an extension of Brekhovskikh and Lysanov’s analysis of the reflection of a spherical wave field from a planar interface. The new solution is accurate throughout the wedge, including the normally difficult modal cutoff regions, where energy propagates through the wedge at grazing angles close to the critical grazing angle; and it is also valid through the hyperbolic caustics that border the region ensonified by each mode.
Theoretical analysis for the reflection of a focused ultrasonic beam from a fluid–solid interface
Authors: Matikas Theodore E. , Rousseau Martine , Gatignol Philippe
Published: October 2005

A theoretical study of the reflection of focused acoustic beams from a fluid–solid interface is presented. The incident field is defined by a Gaussian velocity distribution along a plane emitter. The reflected field is described through its pressure field in a region not restricted to the interface. Nonspecular phenomena were exhibited at any angle of incidence by means of short wave asymptotic analysis. In particular, for incidence near the Rayleigh angle, a distortion of a part of the caustic of the reflected beam including lateral and axial displacements of the focal point is observed.
Photoacoustic waves generated by absorption of laser radiation in optically thin layers
Authors: Khan M. I. , Sun T. , Diebold G. J.
Published: October 2005

The amplitude and phase of the acoustic wave radiated by an infinitely wide, optically thin fluid layer irradiated by a sinusoidally modulated light beam can be found as a solution to the wave equation for pressure. Fourier transformation of the frequency domain expression for the photoacoustic pressure gives the response of the layer to short pulse optical excitation of the layer. Solutions for plane photoacoustic waves generated by an optically thin, isotropic solid layer are given as well. An expression is derived for the far-field photoacoustic wave amplitude emitted by a fluid layer irradiated by a finite diameter laser beam. Experimental photoacoustic waveforms are given for pulsed laser and modulated, continuous wave laser irradiation of several layers.
Material nonlinearities in quartz determined by the transit-time method using direct current field interactions
Authors: Hruska Carl K. , Ng Peggy
Published: October 2005

The experimental data [J. Appl. Phys. 60, 1465–1471 (1986)] on dc field interactions with quartz determined by the transit-time method can provide 17 nonlinear parameters (including 5 fundamental constants) as an independent contribution toward the determination of the third-order electromechanical nonlinearities of quartz. The least-squares estimates of these parameters have been obtained. Their standard errors range from several percent to over 100%. With the assistance of the third-order nonlinear constants determined earlier, 17 estimates of the fundamental nonlinear constants have been obtained from the same data set. They include all electroelastic, electrostrictive, and the third-order permittivity constants of quartz. Their dependence of the third-order elastic constants is fully disclosed. Rigorous interpretation of the meaning of earlier results removes seeming conflicts between the current and the earlier estimates. Reasons are given why the type of experimental data analyzed in this paper is not suited to the determination of third-order elastic constants.
Dipole logging in cased boreholes
Authors: Schmitt Denis P.
Published: October 2005

Shear wave logging through casing can be challenging, especially when the surrounding formation is unconsolidated. This study identifies two possible causes of the problem using synthetic microseismograms, dispersion curves, signal processing scheme based on Prony’s method, and frequency-dependent sensitivity coefficients with respect to the layers’ parameters. The first possible cause is eccentering of the tool when the cased hole is well bonded. The second possible cause is poor bonding, which is modeled by the presence of fluid annulus. An off-center dipole source located in a well-bonded cased hole generates a Stoneley wave that is poorly coupled to the surrounding formation and propagates at a velocity close to the compressional velocity of the borefluid. This Stoneley wave can obscure the formation shear wave signal associated with a slow (unconsolidated) formation. In a vertical well-bonded cased hole, shear wave logging slow (unconsolidated) formations can be reliably performed despite the leaky character of the flexural mode if the tool is well centralized, and a low-source frequency (around 2 kHz) is used. In a highly deviated or horizontal well, where the tool cannot be efficiently centralized, reliable measurements can still be obtained provided the directivities of the source and receivers are perpendicular to the direction of eccentricity. In poorly bonded cased holes, a dipole tool, regardless of its position, excites supplementary low-velocity modes that are associated with vibrations of the steel casing and the presence of an external fluid annulus. The maximum excitation of these modes is located in the low-frequency region, similar to that of unconsolidated formation signals. When the cement is not bonded to the casing, depending on the thickness of the fluid annulus, an unconsolidated formation signal may be corrupted, regardless of the tool’s position within the borehole. The Stoneley wave generated by the off-center source is overpowered by the annulus mode. Even when no interference occurs, the supplementary mode exhibits high, low-frequency energy due to a strong low-frequency coupling with the casing which causes the formation signal to be weak, regardless of the type of formation (fast or slow).

As a consequence, the source must be powerful and the recording system must have a large dynamic range for the formation signal to be reliably detected. When the cement is well bonded to the casing but not to the formation, the effects of the presence of the annulus mode are less drastic.
Acoustic radiation from cylinders with a plane of symmetry using internal multipole line source distributions. I
Authors: Stepanishen P. R. , Ramakrishna S.
Published: October 2005

A new method is proposed to address the two-dimensional exterior acoustic radiation problem from infinite cylinders with a plane of symmetry. This approach, which has its roots in fluid mechanics, is based on the use of internal monopole and dipole line source distributions within the surface. The monopole and dipole line source distributions are determined by prescribed normal velocity conditions over the surface of the shell and are subsequently used to determine the associated surface pressure. The exterior acoustic field is then simply calculated using the surface velocity and pressure via the usual surface Helmholtz integral equation. In contrast to earlier integral equation formulations of the problem the present method does not suffer from either nonuniqueness or result in hypersingular integral equations. Numerical results are presented to illustrate the accuracy of the new internal source density method for the case of a circular cylinder subjected to various specified normal velocity boundary conditions and frequencies. Additional numerical results are also presented for the exterior acoustic radiation problem for a strip on an elliptical cylinder. These results show the characteristics of the surface pressure as a function of the surface velocity and strip width.
Acoustic scattering from cylinders with a plane of symmetry using internal multipole line source distributions. II
Authors: Ramakrishna S. , Stepanishen P. R.
Published: October 2005

A general internal source density approach to evaluate the acoustic scattered field from rigid infinite cylinders that are symmetric about a plane is presented. The approach is based on the use of internal source density line distributions that are either monopoles or dipoles along the plane of symmetry of the surface. A least-mean-square error method is used to match the normal velocity field from the internal sources at the surface of interest with the normal surface velocity due to an incident wave field. The resultant procedure leads to sets of linear algebraic equations that can be easily solved for the monopole and dipole source strengths. The source strengths are subsequently used to obtain the scattered pressure on the surface. The pressure in the exterior field can then be simply determined by evaluating the surface Helmholtz integral formula via usual quadrature methods. Typical numerical results for the surface and far-field pressures are presented for plane wave scattering by a circular cylinder and compared with closed form solutions. To illustrate the general applicability of the approach, plane wave scattering by elliptic cylinders of various aspect ratios is also addressed. These results indicate the characteristics of the scattered pressure as a function of frequency and aspect ratio.
Surface loss, scattering, and reverberation with the split-step parabolic wave equation model
Authors: Schneider Hans G.
Published: October 2005

Moore-Head et al. [J. Acoust. Soc. Am. 86, 247–251 (1989)] have published a method to incorporate loss due to rough surface scattering into split-step parabolic wave equation (PE) codes which then has been extended by Dozier et al. [in Ocean Variability and Acoustic Propagation, edited by J. Potter and A. Warn-Varnas (Kluwer Academic, Dordrecht, 1991)] to include the incoherent scatter. A good agreement with other methods was reported in both cases. However, in the presence of sound-speed gradients this approach is an approximate solution and errors may occur. This will be discussed for some examples. Using the same procedure to estimate the angular acoustic spectrum at the sea-surface, the reverberation from the surface and/or bottom may be evaluated for any generic backscatter function. Two different approaches, based on either reciprocity or backpropagation, will be outlined, with both methods being applicable also to bistatic reverberation. The computationally simpler reciprocity approach has been programmed and results compare well with other models for range-independent environments. A comparison for range-dependent situations with a ray-based model gives good agreement on the main features and all remaining deviations can be explained.
Tidal signals in basin-scale acoustic transmissions
Authors: Headrick Robert H. , Spiesberger John L. , Bushong Paul J.
Published: October 2005

Travel times of acoustic signals were measured between a bottom-mounted source near Oahu and five bottom-mounted receivers located near Washington, Oregon, and California in 1988 and 1989. This paper discusses the observed tidal signals. At three out of five receivers, observed travel times at M2 and S2 periods agree with predictions from a barotropic tide model to within ±30° in phase and a factor of 1.6 in amplitude. The discrepancies at the fourth and fifth receivers can largely be accounted for with a simple model for the generation of baroclinic tides by interactions between the barotropic tides and guyots in the Moonless mountains. These baroclinic tides are phase locked to the astronomical tide-generating forces. A simple model is used to estimate the conversion of energy from barotropic to baroclinic tides by the world’s seamounts. At M2, the conversion amounts to about 1×1018 erg s−1, or about 4% of the total dissipation at M2. Although this estimate is very approximate, it is similar to other published values.
Suppression of stimulus frequency otoacoustic emissions
Authors: Brass David , Kemp D. T.
Published: October 2005

Observations of the suppression of stimulus frequency evoked otoacoustic emissions (SFOAEs) by a second tone were made in human subjects. Measurements were made with the suppressor tone at frequencies and levels at, above, and below the stimulus tone generating the SFOAE. Data were collected with the stimulus tone at a range of levels (20–60 dB SPL), over a range of frequencies and in six different ears, in three subjects. The results were fitted to a phenomenological model, which allowed the data to be expressed as two parameters against the frequency of the suppressor tone. Characteristics of the suppression were examined, in particular the asymmetry between suppression by tones of higher and lower frequency than the tone evoking the SFOAE. At relatively low levels of suppressor tone, suppressors with frequencies higher than the stimulus tone were more effective suppressors than lower frequencies. At higher levels of suppressor tone, the situation was reversed, with lower frequencies being more effective than higher frequencies. These results were discussed in terms of nonlinear interaction between waves in the cochlea. This interpretation was used to estimate the shape of the traveling wave envelope produced by the stimulus tone, from the results of the suppression experiments. It was shown that the estimates of the shapes of the traveling wave envelope were nonlinear, the peak of the envelope becoming sharper at lower levels of stimulus. A simple quantitative model of SFOAE suppression was formulated using concepts of energy flow within the cochlea. This model produced SFOAE suppression results with all the major characteristics of SFOAE suppression from a real, human ear.
Discrimination of spectral shape as a function of stimulus duration
Authors: Dai Huanping , Green David M.
Published: October 2005

Thresholds for discriminating the changes in the spectral shape of simultaneously presented components (profile analysis) are measured as a function of stimulus duration for various complex stimuli. For all stimuli, the threshold decreases with increasing duration until a transition time is reached, and thereafter the threshold remains constant. The amount of change in threshold and the value of transition time appear to be greater for complexes having narrower frequency spacing of the components. The results can be accounted for, at least qualitatively, by assuming that the bandwidth of the auditory filters decreases after the onset of the stimulus.
Local principles of wave propagation in inhomogeneous media
Authors: Gingold Harry , She Jianming , Zorumski William E.
Published: October 2005

Four local principles are proven for waves propagating in a layered medium with a variable wave speed. These principles are (1) that inhomogeneities increase the amplitude of waves generated by a source of fixed strength, (2) that inhomogeneities reduce spatial oscillation, or increase the wavelength, (3) that inhomogeneities decrease transmission, or increase reflection, and (4) that transmission increases monotonically with frequency. Definitions of inhomogeneity, local wave function, and local reflection and transmission coefficients are made as a basis for stating these principles.
Scale model experiments on the validity of the matched asymptotic expansions theory for sound diffraction by curved surfaces of finite impedance
Authors: Berthelot Yves H. , Zhou Ji-Xun
Published: October 2005

Scale model experiments have been conducted to study the diffraction of sound by a curved surface of finite impedance. The theory of matched asymptotic expansions (MAE) offers an alternative to Berry and Daigle’s generalized creeping wave series. [J. Acoust. Soc. Am. 83, 2047–2058 (1988)] Experimental results are in excellent agreement (less than 1 dB) with predictions from the MAE theory both in the deep shadow zone and in the penumbra along the line of sight.
Iterative design of a lensed transducer–reflector system for underwater acoustic imaging
Authors: Oh Jong T. , Park Song B.
Published: October 2005

It is well known that a point source located at the focal point of a parabolic reflector produces a pencil-like beam. Although such an arrangement is widely used as a transmitting/receiving antenna system in radar systems, it is not suitable for underwater acoustic imaging since a relatively large disk-type transducer and a large reflector are needed for high pressure transmission. In this paper a new technique is proposed to iteratively adjust the shape of a relatively small reflector, the transducer positioning, and the shape of a lens attached to the transducer so that hopefully a plane wave is generated at the plane bounded by the circularly symmetrical reflector edge. The resulting field distribution on the aperture is such that the beam is kept from spreading as the wave propagates forward. An experimental system was fabricated with a 2.5-MHz PZT (lead zirconate titanate) transducer of 2.5-cm diameter and a copper reflector of 12-cm diameter. The experimental results showed that the half-power beamwidth was 5.2 cm at 10-m depth and 2.6 cm at 6-m depth and an image of a letter ‘‘K’’ of 15 cm×20 cm was easily detected at a distance of 5 m.
Measuring the strength of auditory fusion for synchronously and nonsynchronously fluctuating narrow-band noise pairs
Authors: Rappold Patrick W. , Mendoza Lee , Collins M. Jane
Published: October 2005

This experiment examines the ‘‘strength’’ of auditory fusion for narrow-band noise pairs. Each pair of noise bands consisted of a target band and a flanker band presented simultaneously. The temporal envelopes of the noise bands within a pair fluctuated either in synchrony (synchronous condition) or not in synchrony (nonsynchronous condition). Each noise-band pair was alternated rapidly with a noise band (captor band) presented alone. The duration of the silent period between a noise-band pair and a captor band [i.e., onset-to-onset interval (OTO)] was decreased by listeners until auditory fusion of the pair was disrupted by capturing the target band into a sequential-stream with the captor band.

Results showed that listeners required significantly shorter OTOs to capture the target bands from the synchronous pairs than from the nonsynchronous pairs, suggesting that strength of auditory fusion was greater for the noise bands that fluctuated in synchrony than for those that did not. The results of this experiment are discussed relative to hypotheses based on auditory stream segregation to explain auditory phenomena such as comodulation detection difference, modulation detection interference, and comodulation masking release.
Approximate descriptions of the sound fields scattered by insonified, submerged, ribbed, flat-ended cylindrical structures
Authors: Brill Donald , Gaunaurd Guillermo C.
Published: October 2005

Backscattering of monochromatic plane sound waves from a soft cylinder of finite length reinforced with N rigid ribs are considered. The Kirchhoff and the Keller approximations are used in various different combinations to produce plots of the target strength (TS) versus incidence angle for purposes of comparison. The angular scattering patterns which result from the combination of methods considered here, agree fairly well away from the broadside incidence where the strongest differences appear. It is felt that some of the predictions of these combinations of methods represent good estimates for the numerical solution corresponding to an elastic cylindrical shell with flat ends and N internal ribs. This paper derives all the formulas used and compares the predictions they yield in various graphs.
Discrimination of moving events which accelerate or decelerate over the listening interval
Authors: Perrott David R. , Costantino Brian , Ball Jennifer
Published: October 2005

Grantham [Grantham, J. Acoust. Soc. Am. 79, 1939–1949 (1986)] has proposed that subjects are able to resolve the velocity of a moving sound source simply by determining the distance traveled and the time required to complete the movement. In the current experiment, subjects were able to discriminate between accelerated and decelerated movements which were identical on both parameters; that is, the accelerated and decelerated movements began and ended at the same locus and required the same amount of time to be completed. The minimum duration required to discriminate between these two movement patterns was 310 and 90 ms, respectively, for displacements of 9° and 18°. These results suggest that, under some conditions, the perception of velocity in the auditory modality may be based upon something more than a simple comparison of the total distance traveled and the time required to complete the movement.
Electrode position, repetition rate, and speech perception by early- and late-deafened cochlear implant patients
Authors: Busby P. A. , Tong Y. C. , Clark G. M.
Published: October 2005

Psychophysical and speech perception studies were conducted on eight patients using the 22-electrode cochlear implant manufactured by Cochlear Pty. Ltd. Four early-deafened patients became deafened at 1–3 years of age and were implanted at 5–14 years of age. Four late-deafened (postlingual adult) patients became deafened at 38–47 years of age and were implanted at 42–68 years of age. Psychophysical studies measured the discrimination of trajectories with time-varying electrode positions and repetition rates. Speech perception studies measured performance using two speech coding strategies: a multi-electrode strategy which coded the first and second formant frequencies, the amplitudes of the two formants, and the fundamental frequency; and a single-electrode strategy which coded the amplitudes of the first and second formants, and the fundamental frequency. In general, the four late-deafened patients and one early-deafened patient were more successful than the other three early-deafened patients in the discrimination of electrode position trajectories and in speech perception using the multi-electrode strategy. Three of the four late-deafened patients were more successful than the early-deafened patients in the discrimination of repetition rate trajectories. Speech perception performance in the single-electrode strategy was closely related to performance in repetition rate discrimination. The improvement in speech perception performance from the single-electrode to multi-electrode strategy was consistent with successful performance in electrode discrimination.
Some empirical observations on sound level properties of recorded piano tones
Authors: Repp Bruno H.
Published: October 2005

Preliminary to an attempt at measuring the relative intensities of overlapping tones in acoustically recorded piano music, this study investigated whether the relative peak sound levels of recorded piano tones can be reliably inferred from the levels of their two lowest harmonics, measured in the spectrum near tone onset. Acoustic recordings of single tones were obtained from two computer-controlled mechanical pianos, one upright (Yamaha MX100A Disclavier) and one concert grand (Bösendorfer 290SE), at a range of pitches and hammer velocities. Electronic recordings from a digital piano (Roland RD250S), which were free of mechanical and sound transmission factors, were included for comparison. It was found that, on all three instruments, the levels of the lowest two harmonics (in dB) near tone onset generally increased linearly with the peak root-mean-square (rms) level (in dB) as hammer velocity was varied for any given pitch. The slope of this linear function was fairly constant across midrange pitches (C2 to C6) for the first harmonic (the fundamental), but increased with pitch for the second harmonic. However, there were two sources of unpredictable variability: On the two mechanical pianos, peak rms level varied considerably across pitches, even though the strings were struck at nominally equal hammer velocities; this was probably due to the combined effects of unevenness in hammer–string interaction, soundboard response, and room acoustics. Moreover, for different pitches at equal peak rms levels, the levels of the two lowest harmonics varied substantially, even on the electronic instrument. Because of this variability, the relative levels of the first or second harmonic near onset provide only very rough estimates of the relative peak levels of recorded piano tones.
A contribution to the unaliased discrete-time Wigner distribution
Authors: Bekir Esmat C.
Published: October 2005

This paper presents a new closed form analytical definition of the unaliased discrete-time Wigner distribution (DTWD), which arises naturally from its continuous-time counterpart, and is straightforwardly implementable for digital signal processing. This DTWD possesses properties that resemble those of the continuous time case. It is shown that this DTWD is the sum of two terms, designated as the even and odd terms, that has interesting symmetric properties similar to those of the discrete Fourier transform. Moreover, this DTWD captures important features of the continuous-time case, and it collapses to the power spectral density function when smoothed with the proper functions. These smoothing functions are limited to be separable. The unaliasedness is validated by computer simulations.
A model for the responses of low-frequency auditory-nerve fibers in cat
Authors: Carney Laurel H.
Published: October 2005

A computational model was developed for the responses of low-frequency auditory-nerve (AN) fibers in cat. The goal was to produce realistic temporal response properties and average discharge rates in response to simple and complex stimuli. Temporal and average-rate properties of AN responses change as a function of sound-pressure level due to nonlinearities in the auditory periphery. The input stage of the AN model is a narrow-band filter that simulates the mechanical tuning of the basilar membrane. The parameters of this filter vary continuously as a function of stimulus level via a feedback mechanism, simulating the compressive nonlinearity associated with the mechanics of the basilar membrane. A memoryless, saturating nonlinearity and two low-pass filters simulate transduction and membrane properties of the inner hair cell (IHC). A diffusion model for the IHC-AN synapse introduces adaptation. Finally, a nonhomogeneous Poisson process, modified by absolute and relative refractoriness, provides the output discharge times. Responses to several different stimuli are presented. These responses illustrate nonlinear temporal response properties that cannot be achieved with linear models for AN fibers.
Audibility of partials in inharmonic complex tones
Authors: Moore Brian C. J. , Ohgushi Kengo
Published: October 2005

These experiments examined the ability of musically trained subjects to hear out individual partials in complex tones with partials uniformly spaced on a scale related to the equivalent rectangular bandwidth (ERB) of the auditory filter. ERB spacings of 0.75, 1.0, 1.25, 1.5, and 2 were used, and the central component always had a frequency of 1000 Hz. All components had a level of 65 dB SPL. On each trial, subjects heard a pure tone (the ‘‘probe’’) followed by a complex tone. The probe was close in frequency to one of the partials in the complex, but was mistuned downward by 4.5% on half the trials (at random) and mistuned upward by 4.5% on the other half. The task of the subject was to indicate whether the probe was higher or lower in frequency than the nearest partial in the complex. The partial that was ‘‘probed’’ varied randomly from trial to trial. Scores for the highest and lowest components in the complexes were generally high (>90%) for component spacings greater than 1 ERB, but worsened somewhat for ERB spacings of 0.75 and 1.0. Scores for the inner components were close to chance level at 0.75-ERB spacing, and improved progressively as the ERB spacing was increased from 1 to 2 ERBs. For ERB spacings of 1.25 or less, the scores did not change smoothly with component frequency; marked irregularities were observed, as well as systematic errors. An explanation for these is suggested in terms of irregularities in the middle ear transfer function. Performance for the inner components tended to be worse for component frequencies above 1000 Hz than below 1000 Hz. It is suggested that this happens because the pitches of partials are partly coded in the time patterns of neural impulses (phase locking), and the precision of phase locking deteriorates progressively with increasing frequency above 1000 Hz. The auditory filter shapes of the subjects were measured for a center frequency of 1000 Hz, using the notched noise method. One subject had a broader auditory filter than the other three subjects, and this same subject generally had more difficulty in hearing out partials from complex tones than the other subjects.
Interaural temporal discrimination using two sinusoidally amplitude-modulated, high-frequency tones: Conditions of summation and interference
Authors: Buell Thomas N. , Trahiotis Constantine
Published: October 2005

This paper concerns sensitivity to interaural temporal delays (ITD) in the envelopes of two, sometimes simultaneously presented, sinusoidally amplitude-modulated (SAM) tones. The SAM tones were fully modulated (typically at a rate of 250 Hz) and had carrier frequencies of either 2 or 4 kHz. Of particular interest were cases in which the delay to be detected (target ITD) occurred in only one spectral region or in both. The reference ITD, to which the target ITD was added, was either 0, 300, or 600 μs. There were three general outcomes: (1) When both regions contained a target ITD, there was an improvement in sensitivity that was quantitatively consistent with an optimal use of independent information. This type of summation was seen even when the target ITDs were added to a pair of SAM tones with two different reference ITDs; (2) when the target ITD was restricted to the higher spectral region, sensitivity was reduced, indicating interference. Interference occurred when the two spectral regions had the same or different reference ITDs and the same or different rates of modulation; (3) sensitivity was unaffected (i.e., no interference occurred) when the target ITD was restricted to the lower spectral region of the pair of SAM tones. These results supplement the observations of Buell and Hafter [J. Acoust. Soc. Am. 90, 1894–1900 (1991)], who used low-frequency tones.
The Lombard reflex and its role on human listeners and automatic speech recognizers
Authors: Junqua Jean-Claude
Published: October 2005

Automatic speech recognition experiments show that, depending on the task performed and how speech variability is modeled, automatic speech recognizers are more or less sensitive to the Lombard reflex. To gain an understanding about the Lombard effect with the prospect of improving performance of automatic speech recognizers, (1) an analysis was made of the acoustic-phonetic changes occurring in Lombard speech, and (2) the influence of the Lombard effect on speech perception was studied. Both acoustic and perceptual analyses suggest that the influence of the Lombard effect on male and female speakers is different. The analyses also bring to light that, even if some tendencies across speakers can be observed consistently, the Lombard reflex is highly variable from speaker to speaker. Based on the results of the acoustic and perceptual studies, some ways of dealing with Lombard speech variability in automatic speech recognition are also discussed.
Comment on ‘‘Time domain Doppler estimators of the amplitude of vibrating targets’’ [J. Acoust. Soc. Am. 9
1, 965–974 (1992)]
Authors: Piquette Jean C. , Van Buren A. L.
Published: October 2005

It is pointed out that the subject paper is valid only in an extremely limited regime, due to the influences of medium nonlinearities.
Generation and Bragg reflection of surface acoustic waves in nearly periodic system of elastic metal strips on piezoelectric half-space
Authors: Danicki E.
Published: October 2005

Propagation of surface acoustic waves (SAW) in a periodic system of metal strips on an anisotropic piezoelectric substrate is analyzed using Green’s function for both the substrate and the system of strips. Appropriate approximations to these functions in spectral domain result not only in a uniform theory of SAW generation and Bragg scattering by strips that accounts for both the electric and elastic properties of the strips, but also in analytical solutions for dispersion relations and a scattering matrix for interdigital transducers. A new, comprehensive model for such transducers is proposed.
Acoustic radiation pressure acting on spherical and cylindrical shells
Authors: Hasegawa Takahi , Hino Yasutaka , Annou Akio , Noda Hideki , Kato Masahiko , Inoue Naoki
Published: October 2005

The acoustic radiation pressure resulting from a plane wave incident on spherical shells and cylindrical shells immersed in a fluid is investigated theoretically in relation to the thickness of the shell and the contents of the hollow region. The results for the frequency dependence of acoustic radiation pressure computed on the basis of the theory are demonstrated for stainless shells with the hollow region filled water or air. Significant differences in acoustic radiation pressure occur when the interior region is changed from water to air.
Measurement of the acoustic nonlinearity parameter in liquid media using focused ultrasound
Authors: Saito Shigemi
Published: October 2005

The principle and the experimental results for a finite amplitude method to measure the acoustic nonlinearity parameter B/A of liquid media using focused ultrasound are presented. The present method takes both absorption and diffraction into account. A liquidlike sample is inserted in the focal region of the acoustic field formed by a spherically focusing Gaussian source. The response of the amplitudes and phases of the fundamental and second harmonic components of the transmitted wave is observed at the post focal region to obtain the experimental value of a quantity named RF, which incorporates the nonlinearity parameter of the sample. The measurement of linear acoustic properties is also carried out using the same focusing source. The value of B/A is determined through comparison between experimental and theoretical values of RF. The experimental results for 4.5-ml volume samples at the fundamental frequency of 1.9 MHz validate the present method. This suggests the possiblity of obtaining the B/A imaging from an acoustic microscope.
Accurate measurements of the sound velocity in pure water by combining a coherent phase-detection technique and a variable path-length interferometer
Authors: Fujii Ken-ichi , Masui Ryohei
Published: October 2005

An automated system for measuring the sound velocity in liquids has been developed by combining a coherent phase-detection technique and a variable path-length interferometer, in which a sample liquid is filled between an ultrasonic buffer and a moving reflector, and phase changes of a given echo of the ultrasonic pulse is measured by a phase-sensitive detector (PSD) as a function of changes in the acoustic path length. For the accurate determination of the changes in the acoustic path length, the displacement of the moving reflector is measured by a Michelson interferometer that is illuminated by a frequency-stabilized He–Ne laser. The sound velocity is determined from a direct comparison of the acoustic wavelength in the sample liquid with the optical wavelength of the laser. In order to check the performance of the apparatus, measurements were performed for distilled water in the temperature range 20–75 °C under atmospheric pressure with a carrier frequency of 16.5 MHz. The precision of the phase measurements by the PSD and systematic errors in the sound velocity measurement are evaluated. The total uncertainty of the sound velocity is estimated to be 0.001%. The results agree with reliable literature values within 0.003%.
Complex harmonic wave scattering as the framework for investigation of bounded beam reflection and transmission at plane interfaces and its importance in the study of vibrational modes
Authors: Van Den Abeele K. , Leroy O.
Published: October 2005

Deformation of bounded beams, when reflected from or transmitted through layered media, have always been discussed in connection with the generation of surface waves assuming an inhomogeneous field of leaking energy reradiating from the interface and interfering with the reflected or transmitted wave. By extending the theory of Claeys and Leroy [J. Acoust. Soc. Am. 72, 585–590 (1982)], who introduced a description of a bounded beam by means of inhomogeneous waves, it is possible to separate the scattered profile from the leaky wave component and prove that all of the features occurring in the neighborhood of critical angles can be explained as purely reflection/transmission phenomena of particular complex harmonic waves, where no propagation along the interface or reradiation is involved. The findings are illustrated for various profiles incident on different layered media both for reflection and for transmission.
A unified analysis of both active and passive damping for a plate with piezoelectric transducers
Authors: Koshigoe S. , Murdock J. W.
Published: October 2005

The complete set of equations for describing the mechanical and electrical behavior of a piezoelectric medium is given. From these equations, the electromechanical equations describing the dynamical behavior of discrete PZTs and their mounting plate are derived. The electromechanical equations are used to explain active damping with the PZTs as actuators and an accelerometer as the sensor. The active damping model is applied to a more realistic case. The transverse displacement and the plate vibration damping are calculated using the electromechanical equations and compared with the experimental results. A comparison of the open loop transverse displacement of the plate as a function of the applied PZT voltage with the corresponding experimental case shows good agreement. The damping of the plate vibration is found to be approximately 20 dB for both the calculation and the corresponding experiment when the plate is driven at the lowest modal plate frequency. A sensor equation describing the output of a PZT used as a sensor is derived with the PZT terminated with an arbitrary impedance. Using the sensor equation, a concise and unified approach is developed for constructing both active and passive damping methods. Two limiting active damping cases (the terminal impedance zero or infinity) and one passive damping case are considered using the sensor equation. A useful design guide for the corresponding active and passive damping methods is determined.
Frequency dependence of cavitation activity in a rotating tube exposure system compared to the mechanical index
Authors: Miller Douglas L. , Thomas Ronald M.
Published: October 2005

Cavitation was produced by focused and unfocused ultrasonic beams in a 60-rpm rotating-tube exposure system. Hemolysis, free radical generation, and hydrogen peroxide were assayed after exposure to determine the dependence of cavitation activity on pressure-amplitude p and frequency f. For unfocused exposure, hemolysis rose rapidly from an apparent threshold pressure amplitude, to a maximum value and then declined gradually at higher amplitudes. Cavitation activity decreased with increasing ultrasonic frequency for a fixed pressure amplitude. Apparent thresholds for unfocused exposure were similar for hemolysis after 15 s and H2O2 production after 15 min. These thresholds increased roughly in proportion to increasing ultrasonic frequency. Cavitation activity was lower and thresholds were higher for focused exposures than for unfocused exposures. The approximate pf−1=0.20 MPa/MHz dependence of the experimental threshold of H2O2 production from 0.745 to 2.95 MHz differs from the pf−1/2=0.24 MPa/MHz1/2 dependence of the theoretical ‘‘mechanical index’’ threshold for inertial cavitation.
Acoustic transmission characteristics of the tympanal tracheae of bushcrickets (Tettigoniidae). II: Comparative studies of the tracheae of seven species
Authors: Heinrich Ralf , Jatho Martin , Kalmring Klaus
Published: October 2005

The transmission characteristics of the acoustic tracheae in the forelegs of seven tettigoniid species were investigated by sinusoidal analysis. The species were selected to represent a range of body sizes and leg lengths. Four subfamilies were included, with two species each from three of them; the tracheae in such closely related pairs could be expected to be similar in shape despite their different dimensions. The tracheae were dissected out for morphometric analysis and compared with one another with respect to their overall dimensions and those of typical subsections. The amplitude-versus-frequency response of acoustic transmission in the tracheae was measured at various positions with a probe microphone. The stimuli were continuous sinusoidal signals at an intensity of 100 or 110 dB SPL. The tracheae of all the species studied here (in males and females) are distinguished by a bandpass-limited transmission characteristic. In the frequency range above 5 kHz (at least to 40 kHz) the sound signals are amplified by 10–15 dB during passage through the tracheae. These results are compared with the threshold curves of the auditory organs and the spectra of the conspecific songs. Although in some cases there are considerable differences in the dimensions of the tracheae, the transmission characteristics are very similar; no specific adaptations to the frequency composition of the conspecific song were found.
Direction-dependent spectral sensitivity and interaural spectral difference in a dolphin: Evoked potential study
Authors: Supin Alexander Ya. , Popov Vladimir V.
Published: October 2005

Sensitivity and interaural intensity difference (IID) dependence on sound frequency and direction was measured in an Amazon river dolphin Inia geoffrensis by recording the auditory nerve evoked response from the body surface. The maximal sensitivity in the horizontal plane was found when the sound direction was 5° to 10° ipsilateral to the recorded ear; the direction dependence of sensitivity was more pronounced at higher frequencies than at lower ones. The IID reached its peak at small azimuthal angles (7.5° to 15°) and higher sound frequencies (100 kHz), or at large azimuthal angles (30° to 45°) and lower sound frequencies (20 to 30 kHz). Each sound direction featured its specific pattern of spectral sensitivity and of interaural spectral difference. The interaural spectral difference fluctuated within a range of more than 20 dB depending on sound direction. The data indicate that interaural intensity as well as spectral difference may be cues for binaural localization of sound direction by dolphins.
Additional remarks on parametric reception near a reflecting plane
Authors: Darvennes Corinne M. , Hamilton Mark F.
Published: October 2005

This Letter supplements a recent article by Darvennes et al. [in Frontiers of Nonlinear Acoustics: 12th ISNA, edited by M. F. Hamilton and D. T. Blackstock (Elsevier, London, 1990), pp. 239–244] on the subject of parametric reception near a reflecting plane when the pump is located on the low-frequency source. For this configuration of the parametric array, theory predicts that moderate discrimination can be provided against multipath interference, and reasonable approximations of the free-field source directivity can be obtained. The purpose of this Letter is to provide new results that further clarify the earlier analysis.