bluuebunny/crossref_metadata_2025 huggingface dataset:
Source depth estimation in waveguides
Authors: Shang E. C.
Published: October 2005

In the present paper an approach to source depth estimation in a waveguide is proposed. The method is based on the mode filtering technique. By using a mode filter, the field sampling data of a vertical array are transformed to a vector which consists of two parts: (1) the eigenfunction of each mode and (2) the modal phase corresponding to the source range. The latter part can be compensated by means of range information extraction proposed in our previous paper [Shang et al., J. Acoust. Soc. Am. Suppl. 1 74, S78 (1983)]. The data vector consisting of a finite number of mode eigenfunctions then becomes ‘‘almost orthogonal’’ and can be used to construct a source depth power estimator. It is well known that the ‘‘closure’’ is a property of a complete, orthonormal set of functions, and because the mathematical expression of ‘‘closure’’ is a correlation type, a correlation operator is a reasonable one for identifying source depth. The resolution is the magnitude of −(H/M), where H is the water depth and M is the effective mode number. Some numerical examples and scale model experimental results are shown.
Excitation conditions of flexural traveling waves for a reversible ultrasonic linear motor
Authors: Kuribayashi Minoru , Ueha Sadayuki , Mori Eiji
Published: October 2005

This paper presents a theory and experiments on a reversible ultrasonic linear motor, consisting of a thin beam, two ultrasonic transducers, and a slider. The slider rides upon the crests of transverse traveling flexure waves propagating down the beam from one transducer to the other.
Structural implications of basilar membrane compliance measurements
Authors: Miller Christine E.
Published: October 2005

Static point-load measurements of basilar membrane compliance were made in the basal region of the excised guinea pig cochlea. Points on a radial line across the basilar membrane were displaced in one-half micron increments and the force required to maintain each increment recorded. The results are interpreted in terms of the material layers of the basilar membrane and displayed as compliance curves. In addition, a beam model of the basilar membrane, including the arches of Corti and the actual geometry of the pectinate zone, is constructed from anatomical data. The free parameters in this model are the modulus of elasticity of the transverse filaments and the effective spring stiffness of the arches. Compliance curves for the model are generated with a finite element approach and the parameters are obtained by requiring optimal agreement with the experimental measurements. The results show that the separation between fiber layers in the pectinate zone is relevant to the effective moment of inertia of the cross section and that the longitudinal coupling between the heads of the arches provides a rigidity to the arcuate zone not seen in the pectinate zone where longitudinal coupling is minimal. The elastic modulus calculated for the filaments is 1.8 GPa, approximately one-half that of keratin, while the cells and ground substance are five orders of magnitude softer.
Changes in the 2f1-f2 acoustic emission and whole-nerve response following sound exposure: Long-term effects
Authors: Dolan Thomas G. , Abbas Paul J.
Published: October 2005

We examined the effects of 1-min tonal exposures on the amplitude of the 2f1-f2 distortion product in the ear canals of cats. These effects were compared with the changes in the whole-nerve action potential (AP) responses to tone bursts following similar exposures. Both the distortion product and AP amplitudes were reduced following exposure. The time courses of AP and acoustic emission (AE) recoveries were to a certain extent similar, and the post-exposure effects depended in similar ways upon the frequency and intensity of the exposure tone (adapter). Assuming that the 2f1-f2 AE is generated by nonlinearities in the motion of the cochlear partition, the reduction in its amplitude suggests that 1-min sound exposures can alter cochlear mechanics. The analogous aspects of the AP and AE post-exposure effects further suggests that components of long-term adaptation as measured by the AP are associated with changes in the mechanics of transduction. Finally, alterations of the middle ear cavities of the cat by opening the bulla or bony septum can result in marked changes in the effectiveness of an adapter in reducing AE amplitude.
The effects of ipsilateral tone burst stimulus level on the discharge patterns of cat lateral superior olivary units
Authors: Tsuchitani Chiyeko , Johnson Don H.
Published: October 2005

Discharges were recorded extracellularly from single units localized in the lateral superior olive (LSO) of barbiturate anesthetized cats. The statistical properties of the unit discharges to monaurally presented tone bursts were determined. Increasing the stimulus level of an ipsilaterally presented tone burst produced an increase in the discharge rate and the emergence and growth of a time-locked discharge pattern in the initial portion of the response. The initial time-locked response was transient and was followed by a nontime-locked sustained response. In the sustained portion, increasing stimulus level produced increases in rate and changes in the interspike interval statistics. Average rate and interval statistics were found to be systematically related. LSO units were differentiated on the basis of rate and pattern of their initial discharges into two main types: the fast and slow chopping units. An analysis of the results indicated that some aspects of response type differences may be related to input characteristics rather than to neuron response mechanisms.
Perceived magnitude of two-tone-noise complexes: Loudness, annoyance, and noisiness
Authors: Hellman Rhona P.
Published: October 2005

An investigation of the perceived effects of tonal components was undertaken to establish a broader data base for quantification and prediction of annoyance of sounds containing added tones. The current study was concerned with two-tone-noise complexes. The stimuli were tone pairs added to a low-pass noise that was attenuated by 5 dB/oct above 600 Hz. Overall perceived magnitude is shown to be a function of the frequency separation (ΔF) between the tonal components, tone-to-noise ratio, and the overall SPL of the noise-tone complex. Results obtained with two tones are compared to those obtained in an earlier study with single tones [R. P. Hellman, J. Acoust. Soc. Am. 75, 209–218 (1984)]. The observed effects appear relevant to the rules governing loudness summation across frequency, to measurements of psychoacoustic consonance and roughness, and to the issue of mutual masking among the component stimuli. The implications of the findings in relation to proposed tone-correction procedures are also discussed.
Effects of flanking noise bands on the rate of growth of loudness of tones in normal and recruiting ears
Authors: Moore Brian C. J. , Glasberg Brian R. , Hess Robert F. , Birchall John P.
Published: October 2005

Five subjects with unilateral cochlear hearing impairments and three normally hearing subjects made loudness matches between tones presented alternately to two ears, as a function of the intensity of the tone in the impaired ear (or the left ear of the normal subjects). The impaired ears showed recruitment; the rate of growth of loudness with increasing intensity was more rapid in the impaired ear than the normal ear. Presenting the tone in the impaired ear with two noise bands on either side of the tone frequency, at a fixed signal-to-noise ratio, did not abolish the recruitment. This suggests that recruitment is not caused by an abnormally rapid spread of excitation in the peripheral auditory system. At low signal-to-noise ratios, a continuous background noise reduced the loudness of the tone more than a noise gated with the tone, suggesting that the continuous noise induces adaptation to the tone. The noise had a greater effect on the loudness of the tone in normal ears than in impaired ears. It is possible that the loudness reduction of the tone in noise is mediated by suppression; suppression is weak or absent in impaired ears, and so the loudness reduction is smaller.
A full wave solution for propagation in multilayered viscoelastic media with application to Gaussian beam reflection at fluid–solid interfaces
Authors: Schmidt Henrik , Jensen Finn B.
Published: October 2005

A new solution technique for wave propagation in horizontally stratified viscoelastic media is presented. The model provides a full wave solution for the field generated by a single source as well as for that generated by a vertical source array. It allows the spatial distribution of the acoustic field to be evaluated at least one order of magnitude faster than with existing models based on the Thomson–Haskell solution technique. The computational efficiency of the numerical code is demonstrated by providing exact numerical solutions for the reflectivity pattern associated with narrow ultrasonic beams incident on a fluid–solid interface near the Rayleigh angle.
An inverse scattering problem of elastic waves
Authors: Hooshyar M. A.
Published: October 2005

The problem of deducing the elastic parameters of an inhomogeneous isotropic medium with spherically symmetric parameters, from the elastic-wave scattering information, is considered. It is shown that the problem can be reduced to a quantum mechanical inverse scattering problem at fixed energy, if the scattering amplitude as a function of angle for the transverse wave of polarization perpendicular to the scattering plane is known for two different values of frequency. In this case, existing inverse scattering theories at fixed energy enable us to find two functions which are related to the density and shear modulus of the medium. The problem of constructing the elastic parameters from the inversion result is studied and tested for synthetic data. Results of the inversion obtained from the Regge–Newton method and the discrete method are compared for scattering data given at different frequencies.
A hybrid BIE+Born series modeling scheme: Generalized Born series
Authors: Schuster Gerard T.
Published: October 2005

A new hybrid modeling method which incorporates boundary integral equations (BIE) and a Born series in solving multibody scattering problems is presented. This method, designated the GBS (generalized Born series), is based on perturbing the surface boundary integral equation (SBIE) matrix into a part to be easily inverted and another part that often need not be inverted at all. Under appropriate conditions the perturbed SBIEs can be efficiently solved by a Born series. Hence GBS avoids the inversion of the relatively much larger SBIE matrix of a pure BIE method and can require several orders of magnitude fewer computations. Even greater efficiency can be achieved if the analytic Green’s function of a scatterer is known. In this case the BIEs are used to compute the Green’s operators of the irregular scatterers and GBS efficiently couples them to the analytic Green’s operator. The key advantage of GBS lies in interactive modeling. Once the Green’s operators of individual scatters are computed then the responses to iterative changes in the location or orientation of a scatterer can be quickly computed. No more matrix inversions are necessary and only a few matrix–vector operations per frequency are required. Computer experiments suggest that many multibody problems can be modeled at each frequency by as few as four terms in the GBS. We have also devised a GBS formulation for layers with arbitrary geometry. Terms in the GBS are analagous to terms in the Bremmer series for plane layers. Hence, the GBS is somewhat akin to a generalization of the Bremmer series for interfaces of arbitrary geometry. Similar to the Bremmer series, the GBS can be used as a powerful interpretation tool by the geophysicist. Each term in the GBS has a clear physical meaning so that careful examination of a synthetic seismogram after each iteration provides clues to the genesis of ambiguous events.
Solution of the acoustic transmission problem by a perturbed Born series
Authors: Schuster Gerard T.
Published: October 2005

In this paper, we present an interactive modeling scheme, which is based upon perturbing the surface boundary integral equations about a reference model in which the Green’s function is known. This Green’s function is computed by a boundary integral equation (BIE) method. The new perturbed equation can be efficiently solved by a Born series and for convenience is designated as the perturbed Born series (PBS). The PBS differs from the series solution to the familiar Lippmann–Schwinger integrals in that it solves a boundary integral which is computationally inexpensive compared to the prohibitively expensive volume integral of Lippmann–Schwinger. For small enough perturbations about the reference model, the PBS will converge quickly for any given source frequency, scatterer size, or contrast in impedance across an interface. The PBS can therefore be used to efficiently compute the dynamic, as well as static, responses to a series of models iteratively perturbed about a reference model. The disadvantage of the PBS is that the convergence rate is not easy to predict and decreases with an increase in scatterer size, source frequency, and perturbations about the reference model.
General characteristics, transition, and control of instability of tubes conveying fluid
Authors: Chen S. S. , Jendrzejczyk J. A.
Published: October 2005

Tests and analyses are made for tubes conveying fluid for two types of support conditions. The objectives are to study the characteristics of different types of instability, the transition of one instability mechanism to another, and the control of instability.
Acoustic radiation potential on a sphere in plane, cylindrical, and spherical standing wave fields
Authors: Barmatz M. , Collas P.
Published: October 2005

We have applied the method of Gor’kov for deriving the acoustic radiation potential on a sphere in an arbitrary sound field. Generalized potential and force expressions are derived for arbitrary standing wave modes in rectangular, cylindrical, and spherical geometries for the case where the sphere radius is much smaller than the wavelength (kR≪1). Criteria for determining radiation potential minima are derived and examples of characteristic spatial radiation potential profiles are presented. Single modes that can sustain stable positioning are discussed for each geometry. The localizing force strengths for representative standing wave modes in the three geometries are also compared. In this paper, we consider the positioning of samples due to acoustic forces only. However, the method developed here is general and can be extended to include gravity or other external forces.
Propagation of acoustic normal modes in a homogeneous ocean overlaying layered anisotropic porous beds
Authors: Badiey Mohsen , Yamamoto Tokuo
Published: October 2005

Attenuation of acoustic normal modes propagating in a shallow ocean overlaying naturally consolidated anisotropic sand beds is calculated using Biot’s theory for porous media. The propagator matrix method is utilized in the analysis to model layered transverse isotropic porous media. The effects of anisotropies in permeability and elastic moduli are studied numerically. It is found that the effect of the hydraulic anisotropy (permeability) of the sand bed on the acoustic attenuation is significant whereas the effect of the elastic anisotropy of the sand bed is not very important. The principle of relaxation is used to interpret the results. It is observed that the energy loss is maximum at a certain frequency which coincides with the relaxation frequency fr of the porous media given by fr=βν/3π ks. Here, β is the porosity, ν is the kinematic viscosity of the pore fluid, and ks is the coefficient of permeability.
Acoustic backscattering at low grazing angles from the ocean bottom. Part I. Bottom backscattering strength
Authors: Boehme H. , Chotiros N. P. , Rolleigh L. D. , Pitt S. P. , Garcia A. L. , Goldsberry T. G. , Lamb R. A.
Published: October 2005

Acoustic backscattering measurements on a sand bottom were made at grazing angles in the range of about 2°–10° in water depth of approximately 15.5 m near San Diego, California (reported by T. G. Goldsberry, S. P. Pitt, and R. A. Lamb, 104th Meeting of the Acoustical Society of America, Orlando, FL, 8–12 November 1982). Data from these measurements have been analyzed to determine the mean value and standard deviation of the bottom backscattering strength per square meter as a function of grazing angle, insonified area, transmit signal type, and frequency. A curved ray path proportional model and measured sound speed profiles were used to determine grazing angle versus time. The mean value followed Lambert’s law for the range of grazing angles measured and for all frequencies used. No significant differences in mean value were observed when the insonified area and transmit signal type were varied. The observed frequency dependence of the bottom backscattering strength per square meter falls in the range from f 1.0 to f 1.5 for this relatively flat, sandy bottom.
The periodic extension of stepwise coupled modes
Authors: Evans R. B. , Gilbert K. E.
Published: October 2005

The method of stepwise coupled modes for studying acoustic propagation is extended to apply to periodic repetitions of a sequence of depth variations. The extension is based on an eigenvalue analysis of the propagator matrix for one period of the depth sequence. Numerical examples are given which compare propagation loss in a waveguide with periodic bottom roughness to that in a waveguide with a smooth bottom. It is shown that propagation loss is significantly greater for the rough bottom waveguide. The increased loss is attributed to scattering of energy out of the waveguide.
A characterization of Arctic undersea noise
Authors: Veitch James G. , Wilks Allan R.
Published: October 2005

Arctic undersea noise is investigated and partially characterized by a probability model suggested by exploration of a sample of such noise. The large size of the data set makes this possible. The model is that of a mixed spectrum, with stationary Gaussian noise intermixed with random sinusoids, and occasional high intensity impulsive noise bursts, which are very short-lived. Due to the complex behavior of the random sinusoids, the noise cannot be considered as stationary in the time frame (10 min) investigated. The validity of the model is checked by testing model predictions against the actual data. In particular, this model makes some predictions about the type of spectrum observed, and these predictions are tested by a nonlinear filtering of the periodogram. A running median filter is used and is shown to asymptotically estimate the spectrum of the Gaussian noise. This filter seems to work fairly well on the data.
Chairman’s introduction: Harry F. Olson Memorial Session
Authors: Miller Harry B.
Published: October 2005

The reason for choosing the papers and the speakers is first given. Then, a brief introduction to each speaker’s paper is given.
Some personal recollections of early experiences on the new frontier of electroacoustics during the late 1920s and early 1930s
Authors: Massa Frank
Published: October 2005

During this brief presentation, time will be turned back a half-century to permit some personal recollections of early experiences as we explored the new frontiers in electroacoustics. The availability of the vacuum tube for the amplification of weak signals made possible the practical application of a variety of wide-range, low-sensitivity transduction techniques for the generation and reproduction of sound. Our training in electrical engineering provided an understanding of electrical measurements and design techniques that we could adapt for new specialized uses during our early stages of acoustic measurements and electroacoustic research. The demands of the new talking picture industry for improved electrical recording and reproduction of sound helped finance the costs of electroacoustic research, which resulted in rapid progress in the sound reproduction and recording industry during the early 1930s. In less than a decade the reproduction of sound was transformed from the primitive limited frequency range of the mechanical phonograph to the high quality electrical recording and reproduction made possible by the rapid advances in electroacoustic engineering.
Theory, ingenuity, and wishful wizardry in loudspeaker design—A half-century of progress?
Authors: Augspurger George L.
Published: October 2005

During the past 50 years the course of professional loudspeaker design has been well documented. The history of high fidelity consumer products is less familiar and more erratic. Loudspeaker designers seem to have embodied three archetypes in varying proportions: the elegant theoretician, the inspired tinkerer, and the wishful wizard. A brief examination of some of their enduring successes, ephemeral favorites, and resounding failures is presented.
Some remarks on electro-mechano-acoustical circuits
Authors: Beranek Leo L.
Published: October 2005

The advanced development of electro-mechano-acoustical circuits dates in the US from Wente (1917), Firestone (1933), Mason (1941), Olson (1943), LeCorbeillier and Yueng (1952), Bauer (1953), Beranek (1954), and Hunt (1954). Earlier significant use of electrical (radio) analogies was made by Darrieus (France, 1929) and Haehnle (Germany, 1932). This paper treats the period in which Olson’s work was centered and cites some examples of the use of the electro-mechano-acoustical circuits in microphones, loudspeakers, and rotational devices.
Pulse-number distribution for the neural spike train in the cat’s auditory nerve
Authors: Teich Malvin C. , Khanna Shyam M.
Published: October 2005

Pulse-number distributions (PNDs) were recorded from primary afferent fibers in the auditory nerve of the cat, using standard extracellular microelectrode recording techniques. Pure-tone and broadband-noise stimuli were used. The number of neural spikes (pulses) n was measured in a set of contiguous intervals, each of duration T seconds. The quantity n varies from one interval to another. These data were then used to determine the PND, which is the probability  p(n,T) of occurrence of n spikes in the time T, versus the number n. The estimated mean and variance of  p(n,T) were obtained. Two different values of T were used. An unexpected observation was that the count mean-to-variance ratio R is relatively constant and independent of the stimulus intensity. Use of the PND as a statistical measure of the underlying neural point process has a number of virtues. For example, the PND readily exhibits the existence of spike clusters (e.g., pairs) for some units. The PND is essentially unaffected by time jitter and time quantization and provides a statistically significant measure for units firing at low rates. A study of the scaled and unscaled pulse-interval distributions (PIDs), under conditions of spontaneous firing, demonstrates that the occurrences of neural events are generally not describable by a renewal process. Our investigation shows that none of the point processes customarily used to model the auditory neural spike train is consistent with all of the data. It appears that the encoding of acoustic information into nerve spikes in the peripheral auditory system takes the form of a cluster point process similar to the Neyman–Scott type. For pure-tone excitation, the PND will be well represented as a multinomial distribution in this case.
Phase effects for a sine wave masked by reproducible noise
Authors: Hanna Thomas E. , Robinson Donald E.
Published: October 2005

A tone-in-noise detection task was used to assess the filtering properties of the auditory system. In the first experiment, ten 150-ms samples of reproducible noise were used as maskers. The signal was a 500-Hz tone either 20 or 100 ms in duration. The 100-ms signal was centered temporally in the noise; the 20-ms signal occurred either at the beginning, center, or end of the noise. The starting phase of the signal was varied from 0°–315° in steps of 45°. Signal thresholds, collected by the method of adjustment, were a cyclical function of starting phase and could be described by an energy model [Green and Swets, Signal Detection Theory and Psychophysics (Krieger, Huntington, NY, 1966/1974)]. A vector description of these data revealed an invariant property of each sample of noise, which we call the ‘‘noise vector.’’ The relationship among the parameters of the noise vectors over the various signal conditions suggest the presence of temporal interactions due to narrow-band filtering. These relationships are consistent with the bandwidth estimates from the energy model which were 36, 36, and 52 Hz for the three subjects. In the second experiment, a 20-ms signal was used and 32-ms maskers were derived from the original ten maskers by deleting portions of the noise that had not occurred simultaneously with the signal. The noise vectors measured for these stimuli differed from those obtained in the first experiment. Moreover, the vectors were better predicted by the energy model than by the vectors of the first experiment, supporting such a model and adding further evidence of temporal interactions due to narrow-band filtering by the auditory system.
Auditory profile analysis: Frequency, phase, and Weber’s Law
Authors: Green David M. , Mason Christine R.
Published: October 2005

This paper reports three separate experiments on different aspects of performance in auditory profile analysis. The first experiment deals with the effects of the frequency and position of an increment in a single component of a multitonal complex. The general results indicate that detection of the signal is easier for components in the mid-frequency range (around 1000 Hz) independent of signal position within the complex. The second experiment investigates the effects of relative phase of the individual components of the complex. Regardless of the number of components, our results indicate that phase has very little effect, even when different phases are selected for each presentation. The third experiment compares the detection of an increment in intensity of a single component, the traditional Weber fraction experiment, and conditions where additional components are present, a profile experiment. The detection of the increment is measured as a function of the level of the standard. The single-tone condition shows the usual near miss to Weber’s law whereas the multitone condition does not. In addition, threshold for the increment is better for the multitone condition than for the single tone condition for levels of the standard up to 70 dB SPL. This last result is investigated for ten observers, five of whom were experienced in profile tasks and five of whom were not. Using a low level standard, the five experienced observers replicate the results described above. The inexperienced observers show the opposite result. On average, they are better able to detect the increment in the single-component condition.
Gap detection in chinchillas with temporary high-frequency hearing loss
Authors: Salvi Richard J. , Arehole Shalini
Published: October 2005

Estimates of auditory temporal acuity were obtained from normal chinchillas by measuring their gap detection thresholds using wideband noise over a range of intensities. Afterwards, the animals were exposed to high-intensity noise whose low-frequency cutoff was progressively lowered towards the low frequencies in five 1-oct steps. The five exposures resulted in a temporary high-frequency hearing loss that progressively spread towards the low frequencies. In addition, there was a systematic and orderly increase in the gap detection thresholds. These results indicate that gap resolution is strongly dependent on the audibility of the high-frequency energy in the test signal.
Pattern analysis of Békésy audiograms
Authors: Chalabi Zaid , Součková Sáva
Published: October 2005

A data-dependent method for the objective classification of Békésy audiograms is introduced. The technique uses orthogonal transformation from the pattern space to a reduced dimensionality feature space that allows a classification process to be implemented digitally. It is argued that this technique, with accretion of audiograms, could form the basis of a data-based system for determining and classifying the coherent structures of the various Békésy patterns with as few as possible a priori hypotheses made about the Békésy ‘‘types.’’
Intonation and text in Standard Danish
Authors: Thorsen Nina Gro/nnum
Published: October 2005

Acoustic analysis of recordings by four Standard Danish speakers reveals that each declarative sentence in a read text is associated with its own declining intonation contour, but together two or three such contours describe an overall falling slope. Individual sentence intonation contours are steeper, and demonstrate greater amounts of resetting between them, in a succession of declarative terminal sentences than in a corresponding string of coordinate main clauses. In other words, the closer relation between coordinate structures is reflected in a more coherent or less segregated intonational structure. The results are compared with other languages, and the implications for the abstract representation of Danish intonation are discussed.
Biomolecular absorption of ultrasound: II. Molecular structure
Authors: Kremkau Frederick W. , Cowgill Robert W.
Published: October 2005

Measurements of absorption coefficients in several globular and linear proteins yield no correlations of absorption with α-helix content or with the number of polypeptide chains in the protein. Removal of all but the primary structure with denaturing agents that convert proteins to random chains causes only small changes in the absorption of globular proteins. Complete denaturing of linear muscle proteins results in large reductions in absorption. Therefore, it is concluded that absorption in globular proteins is insensitive to structural characteristics while in linear proteins it is dependent upon the amount of α-helix content. An alternative explanation of the results is that α-helix contributes to absorption in both globular and linear proteins but tertiary structure in globular proteins reduces absorption because of inhibited solvent interactions.
Relationship between acoustic properties and structure of polyurethanes
Authors: Thompson Corley M. , Heimer William L.
Published: October 2005

Commercial polyurethanes, although convenient, do not provide close sound-speed or density matches with seawater. Several series of diblock copolymer polyurethanes were prepared in order to study the compositional parameters that determine the acoustic properties of this class of compounds. Compositional changes that principally affect the hardblock part of the structure were shown to exert little influence on sound speed or density. Conversely, an increase in the size or quantity of the softblock causes large decreases in the properties, allowing production of polyurethanes with very closely matched properties. Correlation equations for sound speed, density, and specific acoustic impedance are given as a function of calculated number-average molecular weights of the polyurethane softblock. The essential independence of the sound speed from the Shore hardness suggests that the hardblock composition controls the hardness property whereas acoustic properties are determined by the softblock parameters.
Room response measurements in a reverberation chamber containing a rotating diffuser
Authors: Chu W. T.
Published: October 2005

The application of periodic pseudorandom sequences for room response measurements has been extended to chambers containing one rotating diffuser. Results obtained by the new technique compare very well with those measured by the single frequency sweep method. Yet it takes only a small fraction of the time required by the latter method to accomplish the same task.
Stop-vowel coarticulation in 3-year-old, 5-year-old, and adult speakers
Authors: Turnbaugh Karen R. , Hoffman Paul R. , Daniloff Raymond G. , Absher Richard
Published: October 2005

The perturbation of second formant onset values in CV contexts (C=/b,d,g/) caused by the vowels /i/ and /u/ was measured in CVC tokens spoken by three 3-year olds, 5-year olds, and adults. These preliminary results suggest similar patterns of stop-vowel coproduction in all three groups.
Syllable identification by children and adults for two task conditions
Authors: Elliott Lois L. , Busse Lu Ann
Published: October 2005

Both 6-year-old children and adults showed as good performance on a syllable identification task for a test condition having more trials per test run and a lower overall level of positive reinforcement as they did for a condition with fewer trials per test run and a higher, overall level of positive reinforcement. Differences between identification thresholds of children and adults are interpreted as reflecting age-related differences in speech processing rather than differences in responding to the test situation.
Experimental measurement of scattered surface waves using a laser–Doppler technique
Authors: Bouchard G. , Bogy D. B.
Published: October 2005

A laser–Doppler vibrometer was used to detect gated harmonic surface waves traveling along a steel block, together with their reflections from a rectangular plate attached to the block through a viscous couplant. A signal demodulator was designed to allow visualization of the waves on an oscilloscope, and computer data acquisition was performed. Using various plates and couplants, curves showing the reflected/incident power ratio as a function of the wavelength were obtained and compared with those obtained from a previous theoretical analysis. The correlation between the positions, number, and amplitudes of the resonances obtained from experiment and theory was analyzed, as was the influence of the couplant.
Coupled transient response of tiles bonded elastically to a finite flexible plate
Authors: El-Raheb Michael , Wagner Paul
Published: October 2005

Presented are several methods to study a system of tiles bonded elastically to a finite flexible plate responding to an impulse. First, a one-dimensional (1-D) approximation to the system is constructed using Timoshenko beam theory and transfer matrices. This simulates a strip one tile wide. Modal analysis determines the transient response to an impulse of short duration. Also presented are parametric studies of the effect of bond stiffness and the effect of stiffening from inplane stresses produced by large out-of-plane deflections. A two-dimensional (2-D) model is constructed from the eigenfunctions of the 1-D model in a Galerkin method using pairwise products of the 1-D modes as trial functions. Comparison of the two models establishes a factor applied to peak impulse pressure for results to agree.
A review of the MTF concept in room acoustics and its use for estimating speech intelligibility in auditoria
Authors: Houtgast T. , Steeneken H. J. M.
Published: October 2005

The concept of the Modulation Transfer Function (MTF) can successfully be applied to evaluate the quality of speech transmission from a talker to a listener in an auditorium. Typically, depending on the auditorium acoustics, the intensity modulations contained in the original sound are to some extent reduced when measured at a listener’s location, especially for higher modulation frequencies. The implementation of such an acoustical MTF analysis with a sinusoidally modulated test signal is described in detail. The performance of a sound transmission system as revealed by the MTF can be expressed in one single index (the Speech Transmission Index, STI), which relates well to the performance as determined by intelligibility tests with talkers and listeners. A review is given of a series of studies on various aspects of the chain of relations between auditorium acoustics, MTF, STI, and speech intelligibility, illustrating the use of this approach for estimating speech intelligibility, either from MTF calculations at the design stage of an auditorium or from MTF measurements in actual situations.
Second-order statistics and discrete-time detection modeling for partially saturated processes
Authors: Nikolaidis Efstratios , Perakis Anastassios N.
Published: October 2005

The basic problem in underwater detection is formulated under the general assumptions of partially saturated propagation of narrow-band and acoustic signals. Expressions for the joint probability density function (PDF) of ρ, the short-time average root-mean-square pressure at the receiver are obtained. This joint PDF is a general result reducing to the PDF’s for the fully saturated and the unsaturated cases for limiting values of the appropriate variables. Subsequently, defining detection as occurring whenever ρ exceeds a specified threshold level ρ0 and, using the above results, the upcrossing and downcrossing statistics of the envelope process are studied. Closed form expressions for the probability mass functions (PMF’s) of the interarrival time (time between two successive detections) and holding time (time between an upcrossing and the first subsequent downcrossing) are obtained. Results using our partially saturated detection model reduce, in limiting cases, to results already obtained in the literature for fully saturated and unsaturated propagation.
Pitch shift of pure and complex tones induced by masking noise
Authors: Stoll Gerhard
Published: October 2005

Psychoacoustic experiments were performed to measure the pitch-shift effects of pure and complex tones resulting from the addition of a masking noise to the tonal stimuli. Harmonic residue tones with either two or three harmonics and a fundamental frequency of 200 Hz were chosen as test tones. The pitch shifts of virtual and spectral pitches of the residue tones were measured as a function of the intensity of a low-pass noise with 600-Hz cutoff frequency. The SPL of this noise varied between 30 and 70 dB. In another experiment, the pitch shifts of single pure tones corresponding to the frequencies and SPLs of the harmonics of the residue tones were measured using the same masking noise. The results from five subjects for the harmonic residue tones show only a weak dependence of pitch shift on masking noise intensity. This dependence exists for both spectral and virtual pitches. In the case of single pure tones, pitch shift depends more distinctly on noise intensity. Pitch shifts of up to 5% were found in the range of noise intensity investigated. The magnitude of pitch shift shows pronounced interindividual differences, but the direction of the shift effect is always the same. In all cases pitch increases with higher masking noise levels.
A simple, complete numerical solution to the problem of diffraction of S
H waves by an irregular surface
Authors: Bouchon Michel
Published: October 2005

We present a new method to calculate the diffraction of elastic SH waves by irregular surfaces. The technique developed is applicable to boundaries of arbitrary shape and steepness as well as to periodically corrugated surfaces; it is valid at all frequencies. The approach consists of determining the surface forces which cancel the incident stress along the surface. The method relies on the introduction of a periodicity in the surface shape and on a discretization of the boundary at regular spacing. The surface sources which radiate the scattered wave field are obtained by iteration. Examples of calculations and comparisons with other methods are presented.
Neural mechanisms of scanned and stationary touch
Authors: Phillips John R. , Johnson Kenneth O.
Published: October 2005

The neural mechanisms subserving the sense of touch set the limits for the acquisition of information regarding the spatial and temporal characteristics of stimuli impinging on the skin surface. The results of three different psychophysical experiments imply that the skin of the finger pad can resolve the elements of a stimulus separated by 0.9 mm when the stimulus is applied to the skin and held stationary. This resolution limit is only slightly improved (to about 0.7 mm) when movement between the stimulus and skin is allowed. Single-unit recordings from the three classes of primary mechanoreceptive afferents in anesthetized monkeys shows that only one class, the slowly adapting afferents, resolve spatial detail of stationary stimuli near the resolution limit. In addition, slow adaptors appear to resolve moving stimuli (e.g., Braille-dot patterns) more effectively than do the other two classes. However, these observations do not explain the extraordinary capacity of the finger-pad skin for discriminating between fine textures. Neurophysiological evidence suggests that information about such textures (i.e., surfaces with spatial details below the resolution limit) may be conveyed by a code based on the relative engagement of the three receptor populations.
The mutability of time and space on the skin
Authors: Geldard Frank A.
Published: October 2005

Radical shifts in perceived spatial relations can occur through the operation of the principle of sensory saltation. In the realm of cutaneous sensation, where it was first encountered, and also in some auditory and visual situations, any brief stimulus preceding a second one by no more than about 300 ms will show apparent spatial displacement from its veridical position. The degree of deviation is determined primarily by temporal relations between the two stimuli but, secondarily, by intensive ones as well. Limits of the operation of the saltatory effect on the skin have been ascertained by employing a campimetric technique on representative body areas. From the results of such measurement, taken together with consideration of some aspects of the known neural substrate, it is possible to decide among several competing hypotheses concerning the essential seat of the phenomenon. The relation of the saltatory effect to the earlier tau and kappa effects is discussed, as are the possibilities offered by all three to the solution of tactual communication problems and the allied problem of tactile displays.
Research on the Tadoma method of speech communication
Authors: Reed C. M. , Rabinowitz W. M. , Durlach N. I. , Braida L. D. , Conway-Fithian S. , Schultz M. C.
Published: October 2005

In Tadoma, speech is received by placing a hand on the talker’s face and monitoring actions associated with speech production. Our initial research has documented the speech perception, speech production, and linguistic abilities of deaf–blind individuals highly trained in Tadoma. This research has demonstrated that good speech reception can be achieved through the tactile sense: Performance is roughly equivalent to that of normals listening in noise or babble with a signal-to-noise ratio in the range 0–6 dB. It appears that the principal cues employed are lip movement, jaw movement, oral airflow, and laryngeal vibration, and that the errors which occur are caused primarily by inadequate information on tongue position. Our current research includes (1) learning of Tadoma by normal subjects with simulated deafness and blindness, (2) augmenting Tadoma with a supplemental tactile display of tongue position, and (3) developing a synthetic Tadoma system in which signals recorded from a talker’s face are used to drive an artificial face. This research is expected to increase our understanding of Tadoma and its relation to other tactile communication methods, show that performance obtained Tadoma does not represent the ultimate limits of the tactile sense, and provide a research tool for studying transformations of Tadoma.
Tactile aids for profoundly deaf children
Authors: Goldstein Moise H. , Proctor Adele
Published: October 2005

This paper treats acoustic–tactile communication aids for the deaf. Children who obtain negligible help from conventional hearing aids are of particular interest. For the prelingually deaf child tactile aids may facilitate the acquisition of lipreading, and improve vocal production. Although attempts to use tactile aids for the deaf go back many years, only recently have developments in technology led to greatly improved processing possibilities and the feasibility of aids that can be worn. Here, we report case studies in which prelingually, profoundly deaf young children used wearable tactile aids.
Infants’ discrimination of final syllable fundamental frequency in multisyllabic stimuli
Authors: Bull Dale , Eilers Rebecca E. , Oller D. Kimbrough
Published: October 2005

Two groups of nine, 5- to 11-month-old infants were tested for discrimination of a change in peak fundamental frequency (F0) within the final syllable of multisyllabic speechlike stimuli. A visually reinforced headturn discrimination procedure was used to determine sensitivity to increments in peak F0 in synthetic speech in both bisyllabic (CVCVC) and trisyllabic (CVCVCVC) contexts. Discrimination performance was above chance expectation for increments of 10, 20, and 30 Hz relative to a 150-Hz standard. There were no differences in performance attributable to syllable-number context. In a second experiment reassessing two-syllable stimuli, performance was above chance for increments of 5, 10, and 30 Hz relative to the same 150-Hz standard. Both experiments indicated a relatively flat function relating discrimination score and F0 increment. Overall, infant and adult absolute thresholds for a change in F0 appear similar. Effects of threshold, increment, and syllable number are contrasted with earlier results for infant discrimination of both peak-intensity changes and vowel duration increments in the same multisyllabic stimuli.
The use of self-resonating cavitating water jets for underwater sound generation
Authors: Chahine Georges L. , Johnson Virgil E. , Lindenmuth William T. , Frederick Gary S.
Published: October 2005

A self-excited cavitating jet assembly is examined for possible use as an underwater noise generator. The principles of the system are based on matching the natural frequency of a submerged jet with that of a resonant chamber through a feedback mechanism. The case of an organ pipe resonant feed tube is thoroughly investigated. In this case, feedback is obtained by shaping the nozzle in order to optimize its interaction with instabilities in the shear layer of the jet. The performance of the noise generator is evaluated and its characteristics analyzed, including the influence of the pressure drop across the nozzle, the cavitation number, and the organ pipe length. It is observed that the efficiency of STRATOJETs (self-resonating cavitating jets) is more than two orders of magnitude higher than that of a conventional cavitating jet. The knowledge developed in this study allows for selection of the amplitude and frequency of the emitted noise by proper dimensioning of the assembly and correct choice of the functioning conditions.
A time-domain energy theorem for scattering of plane acoustic waves in fluids
Authors: de Hoop A. T.
Published: October 2005

A time-domain energy theorem for the scattering of plane acoustic waves in fluids by an obstacle of bounded extent is derived. It is the counterpart in the time domain of the ‘‘optical theorem’’ or the ‘‘extinction cross section theorem’’ in the frequency domain. No assumptions as to the acoustic behavior of the obstacle need to be made; so, the obstacle may be fluid or solid, acoustically nonlinear, and/or time variant (a kind of behavior that is excluded in the frequency-domain result). As to the wave motion, three different kinds of time behavior are distinguished: (a) transient, (b) periodic, and (c) perpetuating, but with finite mean power flow density. For all three cases the total energy [case (a)] or the time-averaged power [cases (b) and (c)] that is both absorbed and scattered by the obstacle is related to a certain time interaction integral of the incident plane-wave and the spherical-wave amplitude of the scattered wave in the farfield region, when observed in the direction of propagation of the incident wave.