bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of distortion product otoacoustic emissions (DPOAE) with hearing loss produced in a ‘‘toughening’’ exposure
Authors: Henderson Donald , Subramaniam Malini
Published: October 2005

The relation between distortion product otoacoustic emissions (DPOAE) and hearing loss was studied using a ‘‘toughening’’ exposure. The subjects were monaural chinchillas [N=5]; DPOAE were measured using a Virtual 330 and hearing was estimated using evoked potentials recorded from a chronic electrode in the colliculus. Hearing thresholds and DPOAE were measured before any exposure began, then after each 6-h exposure of 0.5 kHz OB at 95 dB SPL for 10 days and, finally, 5 days after the last exposure. Over the 10 days of exposure, the daily threshold shifts became progressively less. Initially, the DPOAE were depressed below the noise of the DPOAE system, but by days 8 to 10, the subjects had recovered to pre-exposure levels even though there were still significant shifts in hearing thresholds. Five days post-exposure, hearing levels were normal and DPOAE were normal or enhanced. Results will be discussed in terms of ‘‘toughening’’ induced by noise exposure. [Work supported by NIH 1 R01 DC01237-01A11.]
Human cochlear traveling wave delays in normal and impaired ears
Authors: Kimberley Barry P. , Lee Anya , Brown David , Eggermont Jos
Published: October 2005

Previous work using electrocochleographic measures [J. J. Eggermont, J. Acoust. Soc. Am. 65, 463–470 (1979)] suggested that human cochlear traveling wave velocities were often increased in ears with cochlear loss. A new method to measure cochlear delays using DPE phase responses has been developed [Kimberley etal., J. Acoust. Soc. Am. (submitted 1992)]. This method relies on more purely cochlear responses in comparison with previous techniques. The method is also rapid and noninvasive. Cochlear traveling wave delays were estimated using the phase responses of distortion product emissions associated with f2 frequencies ranging from 10 kHz to 700 Hz. Frequency-specific delay comparisons were made between two groups, namely 21 young adults (42 ears) with normal hearing and 20 adults (40 ears) with mild/moderate high-frequency hearing losses (30–50 dB HL) at two or more audiometric frequencies. The effect of frequency-specific cochlear hearing loss on traveling wave delays are analyzed and compared with the results previously obtained by Eggermont using electrocochleographic techniques. [Work supported by the Alberta Heritage Foundation for Medical Research.]
Liquid transmission of sound directly into the cochlea
Authors: Gilman Samuel , Mobley J. Phil
Published: October 2005

An implantable hearing prosthesis is being investigated based on the conduction of sound through a liquid-filled tube directly from an electronics module into the cochlea, thus by-passing the external and middle ears completely. Hearing could be provided up to the functioning limits of the cochlea regardless of pathological or functional conditions of the external or middle ear. The system also has wide frequency response with low distortion at high sound levels. Scale model acoustic tests (described in an accompanying paper) confirmed the calculated performance. The band output is linear with applied transducer voltage up to more than 140 dB SPL, is flat (±5 dB) from 150 to 6000 Hz, rising 10 dB to 10 kHz and shows no standing waves. Transmission losses are essentially zero over the entire frequency range so that a maximum efficiency is obtainable. Biocompatible transmission liquid and tubing sizes and material are selected to match the specific acoustic impedance of the cochlea at the interface and couple most efficiently to the transducer.
Performance of a liquid-filled audio transmission line
Authors: Mobley J. Phil , Gilman Samuel
Published: October 2005

The acoustic characteristics of a liquid-filled transmission line have been investigated over the range of 32 Hz to 12.5 kHz. As described in the accompanying paper ‘‘Liquid transmission of sound directly into the cochlea,’’ this method has been investigated to the transmission of audio sound through a scale model of the system. Measurements of dynamic range, frequency response, and distortion were made on an acoustic coupling system consisting of a cylindrical piezoelecric transducer (operated in a radial mode) coupled with a liquid-filled transmission line. When compared with similar methods of transmitting sound into the cochlear such as electromagnetic transducers, mechanical vibrators driving the ossicular chain, and bone conduction transducers, the liquid transmission method shows superior performance. Signal-to-noise ratios range up to 60 dB, frequency responses were flat (±5 dB) over 150- to 6000-Hz range, and distortion measured as low as 0.2% using a 1-kHz fundamental and ten harmonics. These measurements were made at SPL levels exceeding 140 dB using an identical piezoelectric transducer as a receiver terminated with simulated cochlear load.
The quadratic property of the human auditory sensation induced by focused amplitude-modulated ultrasound
Authors: Zeng Shengke , Beard Richard B.
Published: October 2005

Three modes of low-intensity (≤100 mW/cm2) monotone amplitude-modulated (AM) ultrasound are focused on the region of the human cochlear and the human auditory response patterns are observed. The AM ultrasonic signal is defined as f(t) cos ωt, where f(t) is the monotone modulation signal and ω is the angular frequency of the ultrasonic carrier. The three modes of f(t) cos ωt are: (1) carrier-suppressed AM mode, cos Ωt cos ωt; (2) square-rooted AM mode, (1+cos Ωt)1/2 cos ωt; (3) standard AM mode, (1+cos Ωt) cos ωt, where Ω is the angular frequency of the monotone. They are applied in sequence to stimulate the subject. The pattern of auditory sensation of the subject to the ultrasonic stimulations follows the square of the modulation signal, f2(t), which are: (1) cos2 Ωt; (2) [(1+cos Ωt)1/2]2; (3) (1+cos Ωt)2. The subject senses the pure tone of 2Ω for the first mode of the ultrasonic stimulation, the pure tone of Ω for the second mode of the ultrasonic stimulation, and the mixed tones of Ω with relatively weaker intensity of 2Ω for the third mode of the ultrasonic stimulation. The response patterns reveal that the AM ultrasound induced human auditory sensation has the property of f2(t). This quadratic property is similar to the parametric demodulation of the focused AM ultrasound in water which has the form of d/dt[f2(t)], (B≫1) [Novikov, NonlinearUnderwaterAcoustics (Acoustical Society of America, Woodbury, NY, 1987), pp. 86–95]. [Work partially supported by Electro-Stim Corp.]
The effect of the square-root preconditioning on amplitude-modulated ultrasonic hearing
Authors: Zeng Shengke , Beard Richard B.
Published: October 2005

The discovery of the quadratic property of the human auditory sensation induced by the focused amplitude-modulated (AM) ultrasound ( Zeng and Beard, ‘‘The quadratic property of the human auditory sensation induced by focused amplitude-modulated ultrasound,’’ preceding abstract, this meeting) suggests the need for preconditioning of the AM ultrasound stimuli. The preconditioning can cancel the harmonic distortion which is caused by the quadratic effect in ultrasonic hearing. This quadratic harmonic distortion slopes from about −3 dB at 250 Hz (modulation frequency) to −11 dB at 2 kHz (modulation frequency). The preconditioned AM ultrasound is in the form of √‖f(t)min‖+f(t) cos ωt, where f(t) is the modulation signal and ω the angular frequency of the carrier. The non-negative of ‖f(t)min‖+f(t) guarantees that its square root can always be obtained. The auditory perception to the preconditioned AM ultrasound is in the form of the square of the modulation signal, ‖f(t)min‖+f(t), which eliminates the harmonic distortion. In auditory perception test, the ultrasound which is modulated by the preconditioned and unconditioned consonant–vowel–consonant (CVC) syllables is used to stimulate the human cochlea. The subject’s preconditioned ultrasonic intensity thresholds for CVC syllable recognition are lower than the unconditioned ultrasonic intensity thresholds for the same CVC syllable recognition. [Work partially supported by Electro-Stim Corp.]
Forward masking patterns and pitch estimation for bipolar and remote ground stimulation in a subject implanted with a Cochlear Pty. Limited ‘‘20+2’’ cochlear implant
Authors: Cohen Lawrence T. , Clark Graeme M. , Whitford Lesley
Published: October 2005

A new electrode array, recently developed by Cochlear Pty. Limited, enables ‘‘remote ground’’ as well as standard bipolar stimulation. To compare the patterns of electrical stimulation for these two operating modes, forward masking and pitch estimation investigations were performed with a single patient. The masking patterns were studied using a bipolar+1 or a remote ground masker, followed by a bipolar+1 probe. For maskers on apical and middle electrodes, masking patterns were more apical for bipolar +1 than for remote ground maskers, while for maskers on a basal electrode, masking was similar for the two masker modes. For a bipolar+1 masker on a middle electrode, masking was skewed strongly toward the apical end of the array. In the apical half of the array, while remote ground pitch reduced regularly with movement apically, bipolar+1 pitch dropped abruptly to a constant low value for the nine most apical electrodes and was lower than remote ground pitch for each electrode. The results show that remote ground stimulation may provide a different, and at least for this patient a better, range of pitch percepts, as well as other benefits such as reduced current requirement. [Work supported by NIH.]
Free vibration of a rotating annular plate including the effect of bending, membrane, shear deformation, and rotatory inertia
Authors: Côté André , Atalla Noureddine , Nicolas Jean
Published: October 2005

Free response of an annular plate constrained at the inner radius is investigated using a variational approach. In the method used here, special attention has been taken to include all possible effects in linear theory: pure bending, Mindlin’s shear deformation, rotatory inertia, and membrane effect. Membrane effect and bending (pure bending plus shear deformation) are then shown to be independent, thus allowing a separated evaluation of the natural frequencies. The influence of rotation is also investigated for both membrane and bending movement. This general problem is solved using the Rayleigh–Ritz method including symmetric and antisymmetric terms in the polynomials. Special cases where symmetric and antisymmetric natural frequencies are not equivalent can then be shown. The use of polynomials also produced stable results for a future acoustic study. Finally, the critical speed of rotation is determined for a nonrotating observer. Results are presented for every case. [Work supported by N.S.E.R.C. and I.R.S.S.T.]
A new model for predicting the sound transmission properties of orthotropic plates with general boundary conditions
Authors: Woodcock Roland , Nicolas Jean
Published: October 2005

Actually, the structures used in many industrial areas are of particular type: they generally consist of an assemblage of different materials (multilayer structures) and they exhibit anisotropic properties. Real structures are of finite size and their properties are influenced by boundary conditions. The studies on the sound transmission through structures have been limited to the case of simply supported boundary conditions or clamped ones. The present work is intended to extend these different aspects. A new general model is developed for the characterization of multilayer systems consisting of orthotropic plates with general boundary conditions. This modeling concerns the transmission properties of oblique incident acoustic waves or diffuse field. The aim of the study is the development of tools allowing (1) the understanding of the different mechanisms involved in the transmission process, (2) studies on the influence of different parameters such as boundary conditions, the effect of structures size, and orthotropic properties. This model will allow the simulation of real conditions. A variational approach is used with a Ritz basis for the expansion of the flexural displacement of the structure. The different vibroacoustic parameters are determined from the coefficients in the basis. The transmission coefficient requires the calculation of either the radiation impedances, or the radiated power in the far field. An important discussion will be presented concerning this question. Among the areas applications of this model, one can mention aeronautics involved by structures of composite type, architectural acoustics, shipbuilding, etc.
Recent developments in high-frequency ultrasound imaging
Authors: Foster F. S. , Lockwood G. R. , Ryan L. K. , Harasiewicz K. A. , Turnbull D. H. , Pavlin C. J.
Published: October 2005

Current medical diagnostic imaging methods are generally aimed at structures that are larger than 1 mm. Nevertheless, there are numerous important clinical applications for sub-millimeter or microscopic resolution of superficial structures and structures accessible by endoscopic means. In this presentation, the development of high-frequency (40–100 MHz) ultrasound backscatter microscopy (UBM) will be described together with initial clinical and biological applications. UBM is essentially an extension of the powerful B-mode backscatter methods developed for clinical imaging in the 3- to 10-MHz frequency range. The development of new high sensitivity transducers in the 40- to 100-MHz range now permits visualization of tissue structures with resolution approaching 20 μm and a maximum penetration of approximately 4 mm. The design and characterization of ceramic and polymer devices for UBM applications will be discussed. Progress in the use of UBM to visualize the anterior segment of the eye will be reviewed and newer applications such as intravascular imaging, articular cartilage imaging and skin imaging will be examined.
Dispersion predictions for waves along a cylindrical shell immersed in fluid
Authors: Manley Martin G.
Published: October 2005

The behavior of guided flexural waves of an infinite, elastic, circular cylinder immersed in fluid was considered previously [M. Manley, J. Acoust. Soc. Am. 92, 2387 (1992)]. The fluid is of lower density than the solid. The asymptotically exact dispersion relation derived previously is applied to determine dominant terms for dispersion of axial waves in the vicinity of the ring frequency. The effect of fluid loading on the cutoff frequency for the longitudinal mode is examined. [Supported by the PSU Applied Research Laboratory Exploratory and Foundational Research Program.]
Vibrations and acoustic radiation of a simply supported cylindrical shell under circumferentially moving loads: Modeling and experiments
Authors: Panneton Raymond , Laville Frédéric , Berry Alain
Published: October 2005

The vibrational and acoustical behaviors of a simply supported cylindrical shell, immersed in a light fluid and excited with circumferentially moving radial loads are considered in the frequency domain. The equation of motion is developed using an energy method. To solve the problem, the shell displacements and boundary pressures are expanded in a series of invacuo shell modes. The circumferentially moving loads induce a displacement with spatial and temporal dependences of the form ejNφ and e−jNΩt, where N is an integer and Ω is the rotational speed of the loads. For this type of dependence, the equation of motion shows critical speeds for which the modal amplitudes are maximum. Also, a modal analysis is conducted to describe the general behavior of the shell, in the frequency domain, in terms of quadratic velocity, radiated sound power, and radiation efficiency under moving loads. This analysis shows that high levels of quadratic velocity and radiated sound power occur for the critical speeds of rotation. In order to validate this modeling, numerical results are compared with previous published works and laboratory experiments. This paper is the continuation of the paper presented at 124th ASA Meeting [J. Acoust. Soc. Am. 92, 2387 (A) (1992)].
An investigation of mechanisms for drug-mediated cell damage using acoustic cavitation
Authors: Jeffers R. J. , Feng R. Q. , Fowlkes J. B. , Hunt J. W. , Cain C. A.
Published: October 2005

Several different research groups including this one have demonstrated that the application of ultrasound in the presence of certain anticancer agents will increase the invitro and invivo cytotoxicity of the drug significantly beyond the strictly additive effect of ultrasound alone. Recent invitro experiments indicate that the addition of cavitation nuclei in the form of albumin-stabilized microbubbles can greatly enhance the cell killing potential of the combination treatment on HL-60 human promyelocytic leukemia cells. Several measurement techniques currently in use will be described for correlating cytotoxicity with cavitation activity in order to investigate the mechanism for cell damage. One of the more promising methods thus far has been time-integrated subharmonic emission versus cell lysis where the latter is measured by the amount of extracellular lactate dehydrogenase. The use of the subharmonic to indicate the amount and severity of cavitation accommodates variations in cavitation threshold and consistency of cavitation nuclei. [Work supported by USPHS Grant No. CA-55357.]
Integral method for modeling the sound field above a porous material
Authors: Amédin Celse K. , Berry Alain , Champoux Yvan
Published: October 2005

A new concept of a transmission technique for the characterization of porous material is presented. It is based on the accurate modeling of the sound field above the layer of material that rests on an horizontal infinite baffle. The sound field is generated by a waveguide mounted vertically under the baffle with its termination flush to the baffle. The waveguide is assumed to create a uniform distribution of particle velocity at the termination. The field in the material is expressed using a Green’s function that accounts for the multiple reflections on the baffle and at the upper surface of the material. The field above the material is formulated in terms of the pressure gradient distribution over the upper surface. Starting with the boundary conditions at the upper surface (continuity of the sound pressure and normal particle velocity), the collocation method is used to solve for the pressure gradient at a mesh on this surface. This, in turn, allows one to calculate the sound pressure above the material and the transfer function between the volume velocity of the source and this sound pressure. Numerical results are presented, and the potential of this technique for the characterization of porous material is discussed.
Effect of dynamical fluid compressibility and permeability on porous piezoelectric ceramics
Authors: Lacour O. , Lagier Michel , Sornette Didier
Published: October 2005

For frequencies less than the Biot frequency, the ac piezoelectric properties of porous ceramics are studied in the presence of slightly compressive viscous fluids filling the pores inside the ceramics. Two regimes are found: (1) for f smaller than a cross-over frequency fc∼(β/η)L−2, where L is the thickness of the sample and β the fluid compressibility coefficient, the piezoelectric coefficients dij are close to that of the dense nonporous ceramics weighted by the filling factor (1−φ); for f≳fc, the dij are those of the empty porous ceramics as if the fluid was not present. These observations are explained in terms of a frequency-dependent penetration of the fluid pressure inside the porous ceramics as a result on the interplay between fluid compressibility and viscosity. The dependence of the hydrostatic piezoelectric coupling dH=d33+d31+d32 as a function of frequency observed experimentally is compared to an effective medium theory for the piezoelectric properties coupled to a permeability model. The experimental dependence of the cross-over frequency fc on sample sizes and on the fluid viscosity are in excellent agreement with this theory. The study shows that it is thus possible to obtain the desirable property of a high hydrostatic piezoelectric coefficient dH, characteristic of light porous piezoelectric ceramics, and good mechanical properties under high applied pressure with the use of an internal fluid that allows one to equilibriate the pressure without destroying the piezoelectric properties of the porous ceramics.
More on low peak-factor periodic functions
Authors: Hargrove Logan E.
Published: October 2005

A low value of peak factor (PF), the ratio of the range to the rms value of a periodic function, is desirable for radar, sonar, communications, and test signals. A previous paper [L. E. Hargrove, J. Acoust. Soc. Am. 92, 2312 (1992)] described low PF functions constructed from 1≤M≤101 harmonically related and equal-amplitude components with signs derived from spectra components of sinusoidally frequency-modulated sinusoids. In that paper, the flat and bandlimited spectra of the low PF periodic functions consisted of integer multiples n, 1≤n≤M, of a fundamental frequency f1. In the present paper, similar low PF functions consisting of M equal-amplitude components with frequencies which are higher multiples n, 1<p≤n≤(p+M−1), of a frequency f1 are described. A somewhat different set of values for PF obtain for the higher multiple cases. Some comparisons will be made with low PF periodic functions similarly derived from linearly frequency-modulated sinusoids. [Work performed in the ONR Scientific Officer Research Program.]
Modulation detection interference and sound source determination
Authors: Yost William A. , Sheft Stanley
Published: October 2005

This paper will review work on modulation detection interference (MDI), especially in regard to its relationship to sound source determination. MDI represents the difficulty in processing temporal modulation of a probe stimulus when one or more spectrally remote maskers are similarly modulated. Some authors have argued that MDI is an example of cross-spectral processing and is a consequence of the auditory system using coherent modulation of spectrally disparate components as an aid in sound source determination. The evidence for and against these two arguments will be provided. Data from experiments involving complex modulation patterns and multiple maskers will be described along with those from previous work involving simple modulation of a single masker. Attempts to demonstrate that MDI is primarily a cross-spectral phenomenon and that it is related to sound source determination will be made. [Work funded by grants from the NIDCD, NSF, and the AFOSR.]
Comodulation masking release for AM noise maskers
Authors: Eddins David A. , Wright Beverly A.
Published: October 2005

Comodulation masking release (CMR) was measured for a pure-tone signal (2500 Hz) masked by five narrow-band (100 Hz wide) noises (2IFC, 3-down/1-up paradigm). Nose bands were centered at 1500, 2000, 2500, 3000, and 3500 Hz and had a spectrum level of 50 dB SPL. The stimulus duration was 500 ms. Each band of noise was composed of 51 sinusoids. The noise envelopes were manipulated on two levels. On the first level, the phases and amplitudes of the 51 components were either the same (coherent) or different (incoherent) across the bands. On the second level, the bands were amplitude modulated with 10-Hz sinusoids and were either comodulated (same starting phase) or uncomodulated (phase shifted). Mean thresholds for three listeners were 69 and 63 dB SPL for incoherent and coherent noise, respectively, yielding a 6-dB CMR. For both incoherent and coherent noise, thresholds were lower in the presence of modulation. Thresholds were lower by about 3 dB for the uncomodulated noise and 21 dB for the comodulated noise. Thus a CMR occurred on the first level, incoherent minus coherent noise, and on the second level, uncomodulated minus comodulated noise. Combinations of the two treatments may augment or diminish the CMR. [Work supported by AFOSR and NIH.]
Effect of prior stimulation on modulation detection interference
Authors: Sheft Stanley , Yost William A.
Published: October 2005

Thresholds were measured for detecting amplitude modulation of a 2049-Hz probe carrier in the presence of a two-tone masker complex (909 and 4186 Hz). The probe and masker were modulated in-phase at 10 Hz. The effect of prior stimulation on masked probe AM detection was evaluated by either preceding the probe with a 200-ms, 2049-Hz tone burst (precursor) or adding an unmodulated carrier fringe preceding the onset of probe modulation. Precursor and masker onsets were synchronous, with the interval between precursor offset and probe onset (Δt) either 0, 40, or 160 ms. The precursor was either unmodulated, modulated at 10 Hz in-phase with the masker, modulated at 10 Hz antiphasic to the masker, or modulated at 20 Hz. With a Δt of 160 ms, precursor modulation characteristics had little effect. For Δt’s of 0 and 40 ms, modulation of the precursor lowered probe AM detection thresholds with performance generally best with 10-Hz precursor AM. In the fringe conditions, the unmodulated probe carrier preceded the masker onset, with the probe- and masker-modulation onsets synchronous. Fringe duration was either 50, 100, or 200 ms. The addition of the fringe improved performance only with the 50-ms fringe. Results will be discussed in terms of perceptual grouping of stimulus events. [Work supported by NSF.]
Monotic and dichotic modulation detection interference
Authors: Opie Jane M. , Bacon Sid P.
Published: October 2005

Monotic and dichotic modulation detection interference was measured for both practiced and naive subjects who listened to either all monotic or all dichotic conditions first. Subjects detected 10-Hz amplitude modulation of a 1-kHz target tone in the presence of a 4-kHz masker that was either unmodulated or modulated from 2 to 80 Hz at a depth of 100%. The target and masker were presented for 500 ms at a level of 60 dB SPL. Both practiced and naive subjects demonstrated less interference when the masker was presented to the ear opposite the target. On average, the maximum amount of interference was approximately 4 dB in the dichotic condition and approximately 7 dB in the monotic condition. In addition, the tuning for modulation detection was similar for the dichotic and monotic conditions, with the greatest interference observed for masker modulation frequencies that were the same as or similar to the target modulation frequency. [Work supported by NIH.]
Across-frequency interactions in an interaural correlation experiment
Authors: Woods William S. , Brughera Andrew R. , Colburn H. Steven , Ibrahim Hany
Published: October 2005

The work reported here investigated whether across-frequency comparisons can be made when the only relevant information is contained in binaural comparisons. Subjects were required to detect a difference in interaural correlation (IC) between a target band and surrounding fringe bands. Noise stimuli of 500-ms duration and 115-, 354-, 1000-, and 4000-Hz bandwidth, centered on 500 Hz, were used in an adaptive 2I,2AFC task. In each interval, the reference IC was roved between 0.7 and 1.0. In the target interval, the IC was additionally reduced in the 115-Hz target band centered on 500 Hz. Results indicate that the threshold reduction-in-IC is lowest for the 115- and 4000-Hz bandwidth conditions, and highest for the 354-Hz bandwidth condition, consistent with subjects’ use of across-frequency comparisons of binaural information. For the 1000- and 4000-Hz conditions, subjects reported using the presence of a perceived narrow-band object in the target interval as the basis for decision. This basis was eliminated by delaying the onset of the 115-Hz target band 500 ms relative to the fringe band. Resulting thresholds were unchanged or smaller than in the corresponding synchronous condition, possibly due to the subjects’ use of image-width cues.
Why do masker fluctuations as in interfering speech lower the speech-reception threshold?
Authors: Festen Joost M.
Published: October 2005

Two experiments will be presented to explain the difference in speech-reception threshold (SRT) between conditions with a steady-state noise masker and an interfering voice. In experiment I, the possible role of comodulation masking release is investigated by manipulating the comodulation in the interfering voice by introduction of temporal shift among filter bands of various width. The spectral spread of masking from the manipulated interfering voice was controlled by interleaving mutually shifted speech bands with 1/3-octave bands of noise. Although comodulation in interfering speech appears to be very important for the low SRT, the contribution of across-frequencyprocessing of masker fluctuations—commonly considered as the origin of CMR—is only 1.3 dB. In experiment II, the level dependence of masking release with an interfering voice is investigated. The data confirm the hypothesis by Festen and Plomp (1990) that the release from masking with an interfering voice is limited by forward masking. It appears that up to about 55 dBA, the release from masking increases with level up to about 7 dB. Above 55 dBA, the difference in SRT obtained with a noise masker or an interfering voice is constant due to the limited modulation depth of speech.
Introduction to workshop goals
Authors: Brooks Bennett M. , DuBois T. James , Eldred Kenneth M. , Hoover Robert M. , Krishnappa Govindappa , Sutherland Louis C.
Published: October 2005

The goal of this workshop is to further explore the possible future roles of the Acoustical Society in noise and its control. The workshop will begin in the morning with an introductory keynote address with all participants to review the topics, objectives, and procedures for the day’s discussion. The participants will then break out into small subgroups to define key issues and develop action plans. The entire group will reassemble to report, assess, and prioritize the proposed actions in each area.
Everything you wanted to know about ultrasonic atherectomy
Authors: Alliger Howard
Published: October 2005

An ultrasonic wire was developed that can be threaded through the blood vessels to disintegrate or liquefy occlusive material by cavitation. Using an entry point at the groin, the wire, varying in size from 0.018 to 0.032 in., is flexible enough to reach well below the knee as well as the coronary arteries. It is important to prevent transverse whipping motion in the long wire (2–4 1/2 ft.), which reduces the needed linear motion, and tends to break the wire. Here, 110 dB of sound, mostly ultrasound, can be detected coming off the side of the wire at transverse vibration. There is only a small reduction in tip amplitude as the wire is bent. Most heating is at node points when the wire is straight, and at antinodes when the wire rubs against the surrounding catheter. To date, actual invivo human tests have been more encouraging than invivo bench top evaluations. There are several interesting reasons for this.
Acoustic radiation force and acoustical tweezers used in biomedical research
Authors: Wu Junru
Published: October 2005

General analytical expressions for the acoustic radiation forces generated by focused and unfocused ultrasonic beams on a small compressible sphere [J. Wu and G. Du, J. Acoust. Soc. Am. 87, 997 (1990)] and a rigid cylinder [Wu etal., J. Acoust. Soc. Am. 87, 581 (1990)] are derived. A new tool for biomedical research, acoustic tweezers, is developed [J. Wu, J. Acoust. Soc. Am. 89, 2140 (1991)]. Several applications of acoustic radiation force at megahertz frequencies such as determination of the tensile strength of a single actin protein filament are discussed. [Work supported by NIH.]
Speaker-independent speech recognition using an auditory model front end incorporating the spectro-temporal masking effect
Authors: Obara Kazuaki , Aikawa Kiyoaki , Kawahara Hideki
Published: October 2005

Speaker-independent speech recognition experiments using an auditory model front end with a spectro-temporal masking model demonstrated the improvement of the recognition performance and outperformed the auditory front ends without the masking model and the traditional LPC-based front ends. The auditory model front end composed of an adaptive Q cochlear filter bank incorporating spectro-temporal masking has been proposed [J. Acoust. Soc. Am. 92, 2476 (A) (1992)]. The spectro-temporal masking model can enhance common phonetic features by eliminating the speaker-dependent spectral tilt that reflects individual source variation. It can also enhance the spectral dynamics that convey phonological information in speech signals. These advantages result in an effective new spectral parameter for representing speech models for speaker-independent speech recognition. Speaker-independent word and phoneme recognition experiments were carried out for Japanese word and phrase databases. The masked spectrum was calculated by subtracting the masking level from logarithmic power spectra extracted using a 64-channel adaptive Q cochlear filter bank. The masking levels were calculated as the weighted sum of the smoothed preceding spectra. To cover the variability of the time sequences of the spectrum, multi-template DTW and hidden Markov model were used as the backend recognition mechanism. a)Also at ATR Auditory and Visual Perception Res. Labs.
Evidence of word class effects for word recognition in sentences
Authors: Goldman Susan L. , Carrell Thomas D.
Published: October 2005

Previous research has reported that because content words tend to be stressed and function words tend to be unstressed, word class (content−function word) perceptual differences are an artifact of stress differences [A. Cutler and D. Foss, Language Speech 20, 1–10 (1977)]. The present research provides evidence for the validity of word class differences for gated words in a sentence context. Subjects heard successively longer presentations of each target word. The first presentation included the sentence up to the target word onset. The second presentation included the same sentence context plus the first 50 ms of the target word. The duration of each successive presentation was 50 ms longer than the previous presentation. After each presentation, subjects were asked to identify the target word. The target words were content and function words balanced for stress. The results demonstrated that word class, independent of stress, significantly influenced the number of presentations required for identification. The results also showed that for the first presentation, subjects significantly chose words of the same word class as the target word, indicating that word class information is available before phonetic information. [Work supported by Northwestern University dissertation year grant.]
Phonetic classification of plosive voicing using computational modeling
Authors: Darling Angela M. , Rosen Stuart , Huckvale Mark , Faulkner Andrew
Published: October 2005

One approach to investigating the roles of auditory and phonetic processing in speech perception tasks is to compare the performance of listeners with no phonetic processing capabilities (animals and machines) to those of human listeners. Here, a computational model of the peripheral auditory system was coupled to an artificial neural net pattern classifier in order to investigate the essential auditory and phonetic features that distinguish voiced and unvoiced plosives in initial position. The computational model and the human listeners were presented with three stimulus series, varying in voice onset time, representing English bilabials (‘‘ba’’–‘‘pa’’), alveolars (‘‘da’’–‘‘ta’’), and velars (‘‘ga’’–‘‘ka’’). The categorization functions obtained for the model and for human listeners will be compared with regard to their sharpness, and shift of phoneme boundary with place of articulation. [Work supported by the Joint Council Initiative in Cognitive Science/HCI (UK).]
Locating landmarks in utterances for speech recognition
Authors: Liu Sharlene A.
Published: October 2005

Locating landmarks, or acoustically important points, in an utterance is the first step in a proposed method for feature-based speech recognition. The algorithm developed here is designed to locate landmarks caused by closures and releases of obstruent consonants (sounds produced with a pressure buildup behind a constriction) flanked by sonorants. Two characteristics of obstruents are: (1) voicing diminishes or stops completely at the onset and (2) noise is generated during the constricted interval (at the release in the case of stops and affricates). The algorithm thus monitors voicing changes by keeping track of low-frequency signal energy and locates a landmark wherever a rapid change occurs. It also monitors higher frequencies for the presence of noise to aid in the detection of voiceless stop and affricate releases. With appropriate selection of time windows, smoothing intervals, and frequency bands, sonorant/obstruent boundaries for stops, fricatives, and affricates could be detected with only a few percent error. Semivowels and creaky voicing sometimes mistakenly cause a landmark to be detected, but more detailed analysis of the characteristics of these erroneous landmarks may overcome this problem. [Work supported by NSF.]
Speech recognition in noise: Comparing an auditory model with human performance
Authors: Meyer Georg F. , Ainsworth William A.
Published: October 2005

A potential application for models of the auditory system is as the front end to speech recognition systems. The model discussed here consists of a physiologically plausible model of the cochlear nerve and of the major neuron types in the cochlear nucleus, the next stage of information processing in the auditory pathway. The recognition task for the machine and human observers was the identification of 100-ms-long plosive–vowel combinations in three noise conditions: clean, 3 dB and 0 dB S/N ratio. Human listeners were asked to identify the combination under a multiple forced choice regime while the auditory model was used as a front end to a hidden Markov model. Two types of noise were used: Continuous noise and gated noise coincident with the utterance. Physiological experiments show that continuous noise causes a substantial threshold shift while short duration coincident noise has no effect. Psychophysical experiments show that human recognition performance is also a function of the noise type. The performance of the auditory model with plausible threshold shifts is compared with human performance for both conditions.
New range-dependent antisymmetric edge waves along immersed curved elastic wedge with variable cross section
Authors: Chamuel Jacques R.
Published: October 2005

Transient antisymmetric edge waves (100 kHz–1 MHz) were propagated along the sharp edge of an immersed curved elastic wedge with variable cross section. Two basic geometrical configurations were investigated. The first was based on a truncated oblique solid cylinder (A 10-cm-diam aluminum cylinder obliquely cut at 22.5°) forming a convex wedge. The second utilized the intersection of an oblique borehole and a flat solid surface to develop a concave wedge. Aluminum and ice models were studied. The experimental results revealed that the velocity, amplitude, and number of existing antisymmetric edge modes continuously changed as the waves propagated along the range-dependent edge. The antisymmetric edge waves remained nearly nondispersive over a wide frequency range. As the apex angle increased, the number of edge modes decreased. The ratio of the flat side particle displacement to the adjacent curved side particle displacement increased rapidly as the edge apex angle varied between 90° and 135°. Results from free and immersed wedge models were compared. The new findings contribute to the physical understanding of 3-D range-dependent fluid/solid seismoacoustic wave phenomena applicable to underwater acoustics, nondestructive testing, geophysics, acoustoelectronic devices, and propeller noise. [Work supported by ONR.]
Three-dimensional ocean acoustic propagation: Beyond the wedge
Authors: Deane Grant B.
Published: October 2005

In recent years there has been an increasing interest in developing analytical solutions to various range-dependent, three-dimensional propagation problems. Calculation of the sound field from a point source in a homogeneous wedge is such a problem. However, although interesting, the wedge is not representative of the geometry of many shallow water channels. Over continental shelf and slope regions, the bottom is often faceted, that is to say, the channel can be represented as a ‘‘hybrid duct’’ constructed from two or more planar boundaries. The wedge (two planes) and a parallel-sided duct terminated by a wedge (three planes) are examples of hybrid ducts. A technique has been developed for evaluating the field in a hybrid duct with perfectly reflecting boundaries. The new method is based on a novel extension of the method of source images, in which the concept of an image is abstracted into a set of generating sequences and a visibility criterion. A solution will be presented for the sound field in a duct terminated by a wedge as an example of this technique. The method is exact provided the diffracted component of the sound field is negligible. A description of how the source-image approach can be extended to hybrid ducts with penetrable boundaries will be given.
Modeling global-scale three-dimensional sound propagation in the ocean with the parabolic equation method
Authors: Collins Michael D. , McDonald B. Edward , Kuperman W. A. , Heaney Kevin D.
Published: October 2005

The parabolic equation (PE) method is efficient for solving range-dependent sound propagation problems, including relatively small-scale three-dimensional problems. Global-scale three-dimensional problems are well beyond current computer resources because the size of the computational grid increases with range. The adiabatic normal mode approximation, which ignores the effects of mode coupling, is applied to reduce problems of this class to a practical size. Each of the complex modal coefficients is a function of longitude and latitude and is determined by solving a two-dimensional PE. The wave number appearing in the PE, which is a function of longitude and latitude, corresponds to the modal eigenvalue. An interesting description of global-scale three-dimensional propagation can be obtained by solving this two-dimensional problem for a small number of modes. This approach is orders of magnitude faster than the three-dimensional PE even when all of the modes are considered. This model should be applicable to analyzing results from global-scale experiments such as the Perth to Bermuda transmissions [J. Acoust. Soc. Am. 71, 51–60 (1982)] and the Heard Island Feasibility Test [Baggeroer and Munk, Phys. Today 45(9), 22–30 (1992)].
Three-dimensional modeling of low-angle seismoacoustic backscatter
Authors: Bradley C. R. , Stephen R. A.
Published: October 2005

Predictive modeling codes for seafloor backscatter (e.g., finite difference methods) frequently take advantage of coordinate system symmetries in order to reduce the amount of numerical computation required to obtain a solution. Line sources in models with two-dimensional Cartesian coordinates (x,z) are often computationally fastest but assume symmetry into and out of the sagittal plane. Two-dimensional solutions in cylindrical coordinates (r,z) give the correct spreading and waveforms for point sources but range-dependent features in the sagittal plane represent ‘‘rings’’ about the vertical axis through the source and are somewhat unrealistic. In both of these 2-D cases, propagation and scattering are only considered for P-SV waves. In order to study the limitations of these 2-D approaches and to see if they are excluding any significant scattering mechanisms it is necessary to run some fully 3-D models. In addition to out-of-plane scattering of compressional body waves, vertically polarized shear body waves, and Stoneley (Scholte) waves, 3-D models include the new effects of SH body waves and Love (interface) waves. In this paper backscatter coefficients for single facets on a homogeneous seafloor, for a canonically rough (Goff–Jordan) seafloor, and for volume heterogeneities beneath a flat seafloor are compared. For soft bottoms such as sediment the backscatter coefficients of these models are within 3 dB. [Work supported by Office of Naval Research.]
Three-dimensional scattering and wave-type conversion by delineated features in a stratified sea bed
Authors: Fan Huaiyu , Schmidt Henrik
Published: October 2005

The three-dimensional scattering from delineated features in an elastic sea bed, such as faults, small abyssal hills, and extended diapirs, is simulated numerically, and the seismoacoustic wave-type conversion introduced by such reverberant features is addressed. The ocean environment is assumed to be two dimensional: An infinitely long inhomogeneity is imbedded in or penetrating the bottom of an otherwise horizontally stratified ocean. Such reverberant features are assumed to be insonified by an obliquely incident acoustic beam. Due to the fundamental assumption of a two-dimensional environment, this three-dimensional reverberation problem can be treated using Fourier synthesis of 2-D solutions. Here, the two-way solutions are obtained using a modified version of an existing, hybrid wave-number integration-boundary element (WI-BEM) approach [P. Gerstoft and H. Schmidt, J. Acoust. Soc. Am. 89, 1629–1642 (1991)]. This WI-BEM approach inherently decomposes the total field into basic physical components, thus enabling direct identification of the different seismic wave types in the scattered field. The conversion into seismic interface (Scholte) waves and SH waves in the bottom is investigated, and its importance for the bi-static reverberation is discussed. [Work supported by ONR.]
Stochastic analysis of a three-dimensional seismoacoustic field
Authors: Cheng Alexander H-D. , Badiey Mohsen , Jaya Indra
Published: October 2005

Based on geological information existing for a site on the New Jersey continental shelf [Badiey etal., J. Acoust. Soc. Am. 90, 2372 (A) (1991)], a three-dimensional geoacoustic data set was generated using various widely accepted empirical relations. A statistical analysis is performed on the acoustic properties which reveals the random, inhomogeneous nature of seabed sediment. The statistical structure in both the horizontal and the vertical directions are quantified in terms of mean, standard deviation, and correlation length. The data set is then used in a theoretical modeling by both the deterministic and stochastic techniques. The deterministic technique utilizes an anisotropic, inhomogeneous, poroelastic model. The sensitivity of the various physical parameters to the seismoacoustic responses is examined. For stochastic analysis, the Monte Carlo technique is applied. Utilizing the statistical moments obtained from analyzing the field data, a large number of random realizations of seabed acoustic properties can be generated via a spectral technique in one or multi-dimension, and uni- or multi-variate conditions. The deterministic model is then applied to study the effect of the variability of the sediment properties on the acoustic wave field. a)Presently at Office of Naval Res., Ocean Acoustics, Code 1125OA, 800 N. Quincy St., Arlington, VA 22217-5000.
High-temperature fiber optic lever microphone incorporating a single fiber
Authors: Cuomo Frank W. , Nguyen Trung D. , Zuckerwar Allan J.
Published: October 2005

The fiber optic lever microphone [Hu etal., J. Acoust. Soc. Am. 91, 3049–3056 (1992)], as described previously, contains a central transmitting fiber surrounded by six receiving fibers placed with the distal end in the vicinity of the reflecting microphone membrane. Recently, a new approach consisting of a single optical fiber connected to an optical fiber coupler has been implemented. This design provides increased optical throughput, ease of fabrication, improved stability with temperature cycling, and more repeatable sensitivity. The two embodiments will be compared with regard to their theoretical optical transfer functions and experimental performance with temperature cycling to 1000 °F.