bluuebunny/crossref_metadata_2025 huggingface dataset:
Quadrupole projection of the radiation pressure on a compressible sphere
Authors: Marston Philip L. , LoPorto–Arione Salvo E. , Pullen Glenn L.
Published: October 2005

An approximation for the quadrupole projection of the radiation pressure on an inviscid compressible sphere introduced by P. L. Marston [J. Acoust. Soc. Am. 67, 15–26 (1980)] is improved by the calculation of additional terms. The result is applicable to liquid drops in acoustic standing waves in immiscible liquids or in gases. The projection does not generally vanish in the long wavelength limit and the results in this limit are verified with simple arguments based on the pressure distribution for flow around spheres. This limit is also applied to traveling waves and is applicable to the deformation of bubbles, drops, and biological cells.
Abrupt supersonic motion of a point source
Authors: Shankara T. S. , Nandi Kamal Kanti
Published: October 2005

When a point source starts off supersonically at time t = 0, the shape of the disturbed region is different from an open Mach cone. We give a description of this region.
Natural frequencies of concavely shaped polygonal plates with simply supported edges
Authors: Irie Toshihiro , Yamada Gen , Tsujino Masao
Published: October 2005

This note presents the natural frequencies (the eigenvalues of vibration) and the mode shapes of concavely shaped polygonal plates with simply supported edges by the dynamical analogy with membranes.
The effects of noise upon human hearing sensitivity from 8000 to 20 000 Hz
Authors: Fausti Stephen A. , Erickson Deborah A. , Frey Richard H. , Rappaport B. Z. , Schechter M. A.
Published: October 2005

High-frequency (8 to 20 kHz) hearing sensitivity was compared in thirty-six, 20 to 29-year-old military veterans with histories of steady-state or impulsive noise exposure. Threshold shifts were prominent for the steady-state noise subjects from 13 to 20 kHz. Mean thresholds from 8 through 12 kHz were maximally 20 dB poorer than a sample of young adult normals. Audiometric configurations for this group were generally smooth and symmetrical above 8000 Hz. For the impulsive noise group, substantial shifts in sensitivity were seen from 2 to 20 kHz and the high-frequency audiometric configurations were often jagged and/or asymmetrical. The variability of subjects in this group was greater than that seen in the steady-state noise exposed sample. Several case studies are presented to illustrate these characteristics. Measurement of auditory sensitivity from 8 to 20 kHz extends the mapping of basal cochlear function, providing information which often is not predictable from conventional audiometric measurement. This additional information provides for more comprehensive inter- and intra-subject comparison of the degree and extent of threshold changes present.
Sound diffraction around screens and wedges for arbitrary point source locations
Authors: Hadden W. James , Pierce Allan D.
Published: October 2005

A development is presented for the Green’s function for a point source in the vicinity of a rigid wedge. The diffraction contributions to the Green’s function for arbitrary source and listener location is expressed in a form which can be readily evaluated using the Laguerre technique for numerical integration. The present approach offers the advantages of efficient numerical evaluation and of relatively straightforward reduction to well-known analytical approximations in limiting cases. Comparisons with previously obtained experimental and numerical results obtained by Ambaud and Bergassoli [Acustica 27, 291–298 (1972)] are presented. The comparison with the experimental results is excellent; the advantages of the present numerical technique, vis a vis that of Ambaud and Bergassoli, are pointed out.
New algorithm for relaxation spectra in ultrasonic spectroscopy II: Multiple relaxation analysis
Authors: Ito Naoto , Kitahara Noriyuki , Harada Yoshifumi
Published: October 2005

A previously reported algorithm for a single relaxation based on a modified least-square method has been extended to analyze general ultrasonic absorptions with multiple relaxation mechanism. The estimated errors of the experimental data for i-steps (i = 1,2,⋅⋅⋅) multiple relaxations can be evaluated. This technique is successfully applied to the observed ultrasonic absorption of an aqueous solution system of copper and sodium acetates (with each 0.2 mol) with 2-steps relaxations.
Digital solution of cochlear mechanics problems
Authors: de Boer E.
Published: October 2005

Several advantages are incurred when the greater part of the solution to a cochlear mechanics problem is carried out with an analytical method. Many cochlear mechanics problems can be formulated in such a way that they require solution of a specific integral equation in terms of the Fourier transform W(k) of the BM velocity w(x). An analytical solution for W(k) is possible for a certain class of impedance functions. In this paper it is shown how the Fourier transformation to the x domain can be carried out without producing aliasing errors. The impedance function Z(x) must be made periodic in x. For a particular choice of this function, one which puts the main emphasis on BM resonance, the solution to the integral equation can be found from a simple recurrence relation between the spectral components Wn of w(x). The method is illustrated for typical one-, two-, and three-dimensional cochlea models. It is proven that in the region of resonance the (nondigital) solution method published earlier produces nearly equivalent results. The digital method has a much wider scope of application.
AP tuning curves from normal and pathological human and guinea pig cochleas
Authors: Harrison Robert V. , Aran Jean–Marie , Erre Jean–Paul
Published: October 2005

Measures of cochlear selectivity can be obtained from compound responses using tone-on-tone masking procedures [Dallos and Cheatham, J. Acoust. Soc. Am. 59, 591–597 (1976)]. For the normal guinea pig, cochlear fiber tuning is sharper by a factor of 1.8 than AP tuning curves using simultaneous masking (threshold criterion  = 25% N1 amplitude reduction). Anesthesia does not appear to affect AP tuning. In pathological cochleas, AP tuning is broadened by a factor of 2–3, and differences between forward and simultaneous masking curves are reduced. Tuning changes can sometimes occur without threshold elevation. AP tuning curves were obtained from humans during transtympanic electrocochleography. For subjects with near normal thresholds, Q10 dB values (simultaneous masking) are approximately 2.3 at 2 kHz, 3.6 at 4 kHz, and 4.7 at 8 kHz. Using the relationship between cochlear fiber tuning and AP tuning in the guinea pig, estimates of human cochlear fiber tuning are 4.2 at 2 kHz, 6.5 at 4 kHz, and 8.5 at 8 kHz. Patients with threshold elevations of more than 30 dB resulting from cochlear deafness have AP tuning curves less sharply tuned by a factor of 2–3.
Finite difference solution of a two-dimensional mathematical model of the cochlea
Authors: Neely Stephen T.
Published: October 2005

A current, linear, two-dimensional mathematical model of the mechanics of the cochlea is solved numerically by using a finite difference approximation of the model equations. The finite-difference method is used to discretize Laplace’s equation over a rectangular region with specified boundary conditions. The resulting matrix equation for fluid pressure is solved by using a Gaussian block-elimination technique. Numerical solutions are obtained for fluid pressure and basilar membrane displacement as a function of distance from the stapes. The finite difference method is a direct, versatile, and reasonably efficient means of solving the two-dimensional cochlear model.
Interaural correlation discrimination: I. Bandwidth and level dependence
Authors: Gabriel Kaigham J. , Colburn H. Steven
Published: October 2005

Measurements of interaural cross-correlation jnds from two reference correlations at several bandwidths were obtained for constant-total-power and constant-spectral-power Gaussian noise. At a reference correlation of 1, the results indicate that for bandwidths less than or equal to 115 Hz the jnd remains at a constant value of approximately 0.004, and monotonically increases (discrimination performance degrades) to approximately 0.04 as bandwidth increases above 115 Hz. At a reference correlation of 0, the jnd decreases (discrimination performance improves) from approximately 0.7 to 0.35 as the bandwidth increases from 3 to 115 Hz, and remains at a constant value of approximately 0.35 for bandwidths greater than 115 Hz. A decrease in the spectral level causes an increase in the jnds at a reference correlation of 1, and no change in the jnds at a reference correlation of 0. Of the three models tested, none is able to completely describe all of the empirical results.
Piecewise-planar vowel formant distributions across speakers
Authors: Broad David J.
Published: October 2005

A previous study [D. J. Broad and H. Wakita, J. Acoust. Soc. Am. 62, 1467–1473 (1977)] showing that one female speaker’s first three vowel formant frequencies clustered about a two-part piecewise-planar surface is extended to five additional speakers. For each speaker, a similar two-plane representation is found, with the rms spread of the data about the planes ranging between 69 and 103 Hz. The orientations of the planes for the different speakers are similar: The front-vowel planes make an average angle of 10° to the average front-vowel plane, while the back-vowel planes make an average angle of 13° to the average back-vowel plane. Nearly all these departures from the average are significant at the 99% level. The hypothesis of uniform scaling of vowel formant frequencies between speakers must therefore be rejected if it is carried strictly to three dimensions. This is also shown by the positions of the planes. The speakers do, however, group into two almost uniformly scalable subsets. Finally, the third formants of the retroflex vowels for most of the speakers are lower than would be predicted solely from exploitation of low-F3 regions of the piecewise-planar surfaces.
Comments on ’’An improved WKB calculation for a two-dimensional cochlear model,’’ [J. Acoust. Soc. Am. 68, 147–148 (1980)]
Authors: Viergever Max A.
Published: October 2005

Steele and Miller presented an alternative method of calculation for the WKB solution of the standard two-dimensional cochlear model. They claim that their results improve upon the original WKB calculations of Steele and Taber [J. Acoust. Soc. Am. 65, 1001–1006 (1979)], notably near the resonance location. This claim is shown to be incorrect. A recently developed calculational procedure which does give better results than those of Steele and Taber is briefly outlined.
The problem of different interaural time differences at different frequencies
Authors: McFadden Dennis
Published: October 2005

Recent research reveals that the interaural time difference produced by a sound source located off the median plane of the body is not frequency independent. The problem this poses for the auditory nervous system is discussed.
Torque generated by orthogonal acoustic waves—Theory
Authors: Busse F. H. , Wang T. G.
Published: October 2005

An analytical calculation of the torque generated by orthogonal waves is reported. This torque is a result of a viscous effect, rather than the Bernoulli effect as in Rayleigh’s torque. The agreement between the reported experimental values and this calculation is excellent.
Sound velocities and B/A in fluorocarbon fluids and in several low density solids
Authors: Madigosky Walter M. , Rosenbaum Ira , Lucas R.
Published: October 2005

Sound velocities were obtained in six fluorocarbon fluids, two syntactic foams, and two low density solids. Temperature and pressure ranges considered were 0 °–30 °C and 1–700 kg/cm2. An equation was fit to the data. This equation was then differentiated to permit the calculation of the nonlinear parameter, B/A, and Rao’s constant. Comparisons of these data with those obtained by other authors are made wherever possible. Very low sound velocities are observed in fluorocarbon fluids and these fluids have the highest values of B/A reported thus far.
Application of Ludwig’s uniform progressing wave ansatz to a smooth caustic
Authors: Stickler D. C. , Ahluwalia D. S. , Ting L.
Published: October 2005

It is well known that the usual harmonic ansatz of geometrical acoustics fails at a caustic and that uniform expansions can be found which remain valid in the neighborhood of the caustic and reduce asymptotically into the usual geometrical acoustic ansatz far from the caustic. A similar uniform ansatz can be constructed for transient acoustic fields using the so-called progressing wave ansatz. In this paper some of the details of this construction are considered for a point source in a time independent, refracting medium in which a smooth caustic is formed. The time dependence at the source is taken to be a rather general function of time. Particular attention is given to the nature of the leading term of the uniform progressing wave expansion and its construction from the nonuniform harmonic ansatz. Explicit expressions are obtained for times near the direct arrival time and the caustic arrival time as well as for large time. An analytic example is examined when the squared refractive index is linear and some numerical results for this case are presented.
Secondary states of vibrating plates
Authors: Putnick Leonard J. , Matkowsky Bernard J. , Reiss Edward L.
Published: October 2005

A perturbation method is used to obtain a new class of periodic motions for the nonlinear vibrations of rectangular, elastic plates. The dynamic von Kármán plate theory is used in the analysis. Periodic solutions bifurcate at the natural frequencies of free vibration of the linearized plate theory. The new solutions bifurcate from these periodic solutions. Thus they are states of secondary bifurcation.
Dynamic stability of orthotropic annular plates under pulsating torsion
Authors: Tani J.
Published: October 2005

The dynamic stability of clamped, polar orthotropic annular plates under pulsating torsion is theoretically analyzed with the effect of the static torsion taken into consideration. The Galerkin method is used to reduce the problem to that for a finite degree-of-freedom system, the stability boundaries of which are determined by utilizing Hsu’s result [J. Appl. Mech. 30, 367–371 (1963)] for coupled Hill’s equations. The instability regions of both principal and combination resonances are determined for a wide range of exciting frequencies. The variation in the polar orthotropic material property is found to change significantly the wavenumber dependence of the dynamic stability.
Comments on the coherent and incoherent nature of a reverberant sound field
Authors: Chu W. T.
Published: October 2005

Is is proposed that reverberant sound fields should be classified with better-defined characteristics in terms of coherence and incoherence. Their exact nature created under different types of signal excitation and room condition are explored with the object of clarifying the conditions for which various results from the statistical theory apply.
Sound decay in reverberation chambers with diffusing elements
Authors: Kuttruff K. Heinrich
Published: October 2005

Sound scattering bodies are frequently used to improve diffusion in reverberation chambers and generally produce reverberation on their own. This effect is negligible at relatively low diffuser densities; in this range the effect of increasing diffusion prevails. At high densities of the scattering bodies, however, reverberation caused by the latter makes the usual reverberation formulae unapplicable. Between both limiting cases there is an optimum range of diffuser density. This is calculated theoretically as well as determined by Monte-Carlo simulations.
New models on the ocean acoustic detection process
Authors: Psaraftis Harilaos N. , Perakis Anastassios N. , Mikhalevsky Peter N.
Published: October 2005

The basic problem of the ocean acoustic detection process is formulated analytically under the assumption of fully developed saturated phase random multipath acoustic fluctuations. Detection is defined as occurring whenever ρ, the root-mean-square pressure at the receiver, exceeds a specified threshold level ρ0. Two models, one exact and one approximate, are developed for obtaining the probability density functions of the time between two successive detections and of the time ρ is above ρ0 (holding time). The two models are compared with one another and with the extensively used (λ, σ) model. One of the reasons that the latter model has a limited success in practice is the inability to estimate the appropriate value for λ, a parameter which is determined empirically. In this paper we have derived an appropriate value for λ, in terms of ν (the single path root-mean-square phase rate), σ21 (half the long time average mean-square pressure at the receiver) and ρ0 (the threshold level). Using this equivalent value for λ, we observe that our exact and approximate detection models exhibit similar long-term behavior but markedly different short-term characteristics as compared with the (λ,σ) model. This is due to the memory of the process, a property that cannot be accounted for in the (λ,σ) model. A comparison of these models with data obtained from various field experiments demonstrates, in most cases, an improved capability over the (λ,σ) model.
Post masking with two maskers: Effects of bandwidth
Authors: Fastl Hugo , Bechly Matthias
Published: October 2005

Thresholds of test tone impulses masked by one masker M1 or two maskers M1+M2 are determined in a post-masking (forward masking) stimulus paradigm. Test tones are centered at masker M1 and the bandwidth of M1 is varied. The magnitude of the threshold decrease ΔL caused by the addition of masker M2 depends on masker M1 as follows: Large ΔL for narrow-band noise and AM tone, medium ΔL for pure- and QFM-tone, almost no threshold decrease for broadband noise-masker M1.
On the theory of stress-constrained optimum compliant tubes and uniform tube arrays
Authors: Brigham Gerald A.
Published: October 2005

A low-frequency model for the plane-wave transmissitivity of a planar uniform grating of compliant tubes is combined with a tube stress model to determine maximum array resonant reflectivity and maximum resonant bandwidth. The study shows tubes of intermediate roundness are optimum in compliance, size, weight, and resonant bandwidth. A comparison is made of various materials and concludes that composite tubes made of S glass fiber and epoxy resin have maximum compliance and generate the optimum grating acoustics.
Rayleigh scattering by compressible, movable bodies of revolution
Authors: Junger M. C.
Published: October 2005

Rayleigh’s solution for the scattered field of an acoustically small sphere of finite bulk modulus and density is extended to finite cylinders and other bodies of revolution. The analysis has applications to scattering by elastic spherical and cylindrical shells and by zooplankton.
The effect of the angle of incidence on the measured residential acoustical insulation
Authors: Bechrakis N. , Hall F. L. , Birnie S.
Published: October 2005

The angle of incidence is a major variable for calculating transmission loss from field data [ASTM 336 77]. This suggests that the acoustical insulation of residential construction vary with the relative location of the flight paths and the housing. Alternatively, the number of reflected paths in normal residential areas may be so great as to override any such effect. This paper tests the hypothesis that the acoustical insulation of residential construction is affected by location relative to the flight path, using field transmission loss data collected during summer 1980 for thirty rooms in the Toronto area. Two cases are compared. In the first, the flight path is perpendicular to the plane defined by the element of interest, while in the second, the flight path is parallel to the same plane. Road traffic sites are also used as they are similar to the second case. For the first set of cases, the acoustical insulation for different sections of each flyover is also studied.
A free field room for measuring pure tones
Authors: Angevine O. L. , Angevine E. N.
Published: October 2005

A low-cost hemi-anechoic laboratory for machine noise measurement is described. The special difficulties in qualifying tests of a hemi-anechoic chamber were resolved using Moreland's procedure (NOISE-CON 79 Proceedings, 365–372). These tests disclosed anomalies in the free field characteristics near 250 Hz, which were traced to even spacing of the sound absorptive wedges. These anomalies were reduced by splitting the space between wedges with absorptive dividers. The conclusion is drawn that regularities in wedge size or spacing must be particularly avoided when such test chambers are to be used for measurement of pure tones.
Second-order statistics of finite estimation of the spatial variance and time averaging in a reverberation chamber with a rotating diffuser
Authors: Elko Gary W. , Tichy Jiri
Published: October 2005

The accuracy of measuring the sound power that a source radiates into a reverberation chamber is directly related to the precision of the finite space-time average of the pressure squared. It is well known that a rotating diffuser reduces the normalized spatial variance of the pressure squared in a reverberation chamber excited by a pure tone. The relative decrease of the spatial variance by the rotating diffuser has been called the “figure of merit.” Determination of the F.O.M. therefore depends on the finite sample size estimate of the normalized spatial variance. The statistics of the finite sample size spatial variance estimate will be discussed and confidence levels will be shown. Time averaging requirements of the pressure modulus for the rotating diffuser modulation process will be presented for both linear and exponential averaging.
Noise and vibration controls for variable air volume systems in new chemistry laboratories
Authors: Sweitzer Glenn
Published: October 2005

New chemistry laboratories require variable air volume systems to meet high exhaust airflow requirements and to reduce energy consumption during varied duty loads. Limited building budgets often introduce shortcuts into these systems that compromise the noise and vibration environments for chemists and their increasingly sensitive instrumentation. If acoustical planning is not included in the initial design, remedial noise and vibration controls will probably be limited, time-consuming, and expensive to implement. Three chemistry laboratories that required acoustical evaluation and remedial controls following recent building construction serve as case studies. Noise and vibration sources discussed include variable air volume supply fans, exhaust air fans, walk-in and counter-top exhaust hoods, and their respective ductwork and control systems.
Propagation of sound in ducts lined with circumferentially nonuniform absorbents
Authors: Vaidya P. G.
Published: October 2005

The state-of-the-art of using sound absorbers in ducts is almost entirely limited to the analysis and testing of uniform, locally reacting linings. There is, however, a growing concern that this might lead to designs which are far from optimum. One form of non-uniformity which is expected to be beneficial is that along the circumferential direction. One great difficulty in implementing this concept is lack of availability of separable solutions. As a result, extremely costly numerical techniques are being tried. This paper shows that in many cases, such techniques are unnecessary. For a general sinusoidal variation in the absorbent properties, in the circumferential direction, closed-form solutions could be obtained. These solutions are non-separable. The solutions show that it might be possible to convert a lower circumferential order mode into a higher order one, which might be easier to attenuate.
The electret telephone transmitter
Authors: Baumhauer John C.
Published: October 2005

Sound striking an electret transmitter's movable electrode or diaphragm yields a capacitance variation in an adjacent air gap, wherein a biasing electrostatic field is modulated. That field is shown to be produced by a fixed electret charge implanted near the surface of a solid dielectric within the device. Electret principles such as equivalent voltage are described analytically. A transmitter mathematical model is depicted including the mechanacoustic structure, the transduction, and the preamplifier. It is approximated by an equivalent electrical circuit with four degrees of freedom. The appropriate derivation of diaphragm lumped parameters for a capacitive-type transducer is discussed. The role of frequency response criteria peculiar to telecommunications and diaphragm electrostatic stability limitation as they affect parameter optimization is outlined. A thermal stabilization procedure is described which minimizes long-range viscoelastic changes in a metallized Teflon® (registered—E. I. DuPont) diaphragm's mechanical response. The history of the condenser and electret microphones will be briefly reviewed. Modern electret advantages over carbon microphones will be outlined including dc power consumption, size, electroacoustic linearity, and mechanical vibration sensitivity.
Effects of consonantal context on vowel lipreading
Authors: Montgomery Allen A.
Published: October 2005

In this study physical measurements of talkers' lips during production of CVC monosyllables were correlated with perceptual confusions among the utterances during lipreading. Five talkers were videotaped producing a large set of CVC's with /f,v,w,r,p,b,t,d,h,g/ as consonants and /i,ɪ,a,ᴜ,u/ as vowels. Tracings were made from the tape and intelligibility of lipreading was determined by normal and hearing-impaired viewers. It was found that in contexts with minimal labial coarticulation the variance in vowel confusions was almost completely explained by static measurements of lip height and width at the point of maximal vowel constriction. In bilabial, rounded, and labio-dental contexts, however, it was found that (a) overall intelligibility of the vowel was reduced, (b) lip height and width predicted a high percentage of the perceptual confusions among the vowels, but vowel duration and lip trajectory improved the prediction in some cases, and (c) considerable variation existed among talkers and the intelligibility of individual talkers could be predicted by a small set of measurements of the lips during vowel production. [Work supported by Department of Clinical Investigation, WRAMC.]
Identification of steady-state sung vowels
Authors: Chew Stephen L. , Gottfried Terry L.
Published: October 2005

Sung vowels provide an excellent opportunity to study the information present in the vowel steady state. Ten American English vowels /i,I,e,ɛ,æ,ɑ,ʌ,o,U,u/ in /b/-vowel-/d/ syllables were sung by; a professional male singer at seven different pitches: C3, E3, A3, C4, E4, A4, and C4. Syllable length ranged from about 500 to 900 ms. An algorithm was used to extract an approximately 200-ms sample of the steady-state portion, carefully avoiding initial and final consonant transitions. Listeners attempted to identify the vowel using only this steady-state information. Removal of the consonantal context increased vowel identification errors. In addition, identification accuracy was lower for vowels sung at the higher pitches. The error rate was greater for back vowels than for front vowels, especially at the higher pitches. Confusions between /ɑ/ and /ʌ/ were especially common. The effect on vowel identification of using a “chest” voice versus a “head” voice was also investigated. Results are discussed with regard to the adequacy of steady-state information for vowel identification. [Work supported by NIMH, NICHHD, and NSF.]
Multidimensional vocalic perceptual space: How many dimensions?
Authors: Lonchamp F.
Published: October 2005

In published sources, the number of recovered dimensions ranges from 2 to 6. From our experiment on 40 French subjects scaling 10 vowels [i,e,ɛ,a,ɔ,o,u,y,ø;,œ] and from a reanalysis of 4 studies [Hanson (1967); Mohr and Wang (1968); Singh and Woods (1971); Terbeeck (1977)] using both metric (Indscal) and nonmetric (Kruskal) methods, the following conclusions can be drawn: (a) Variance accounted for can reach 90% for two-dimensional group data, leaving little room for more than a third dimension. (b) The first two (unrotated) dimensions and the F1−F2 plane are highly correlated. The most reliable criterion for the presence of a third dimension seems to be the stability of stimuli ordering for repeated analyses from random starting configurations with both methods. Retroflex [vů] and front (nonhigh) rounded [ø,œ] vowels consistently end up at one end of the axis. No ceiling effect of similarities versus distances can explain this ordering for the nonmetric approach. Tentatively, the common acoustical feature between [vů,ø,œ], i.e., the closeness between F2 and F3, is suggested as the third dimension correlate. No evidence for a 4th dimension has been found.
Effects of nonessential cues on the perception of English[s] and [sš]
Authors: Whalen D. H.
Published: October 2005

Earlier studies [Whalen, J. Acoust. Sec. Am. (1981); Mann and Repp, Percep. Psychopys. 28, 213–228 (1980)] have shown that vocalic formant transitions contribute to the [s]-[sš] distinction if the noise cue is ambiguous between [s] and [sš]. It is not clear, however, whether the transitions have any perceptual effect when the noise cue is unambiguous. To see if they do, a reaction time study using natural tokens of [sa], [sša], [su], and [sšu], was run. Each vocalic portion of these syllables was combined with each noise portion. In one condition, the subjects were asked to identify the fricative only ([s] or [sš]); in a second condition, they had to identify the whole syllable ([sa],[sša],[su],[sšu]). In the two-choice condition, there was no significant difference in reaction times to the stimuli with appropriate and inappropriate transitions. In the four-choice condition, however, reaction times were significantly longer when the transitions were inappropriate. This difference indicates that an inessential cue can have an effect in perception, if the subjects must wait until after that cue has occurred to make their identification. [Research supported by NICHD and BRS.]
The role of formant transitions in the identification of Spanish fricatives
Authors: de Manrique Ann María B. , Massone María Ignacia
Published: October 2005

The role played by formant transitions in the identification of Argentine Spanish voiceless fricatives: [f, s, ∫] was evaluated by cross-splicing technique of natural syllables. The test tape consisted of a set of CV syllables which were formed by the recombination of each friction portion with each vocalic portion. The vocalic portion was one of the Spanish vowels [i, a, u]. The average responses of ten listeners to these stimuli showed that the acoustic cues provided by the friction portion were sufficient for the identification of the fricative sounds. In the case of [f], the results are not in agreement with previous data obtained for English listeners [K. Harris, Lang. Speech 1(1), 1–7 (1958)], a discrepancy which may be explained by the different linguistic systems. Formant transitions seem to play some role in s/∫ distinction. But its relevant role seems to be preventing a vowel effect on the preceding fricative.
A study of recent data sets exhibiting wind-induced ambient noise
Authors: Li H.
Published: October 2005

The wind dependence of underwater ambient noise has recently received considerable attention, especially at low frequencies (1–500 Hz). In this paper, major findings are presented based on a study of several recent data sets exhibiting wind-induced underwater ambient noise. The results are described separately for three frequency bands. At the frequency band 100–500 Hz, the wind dependence can be identified without difficulty. Wind-dependent spray noise and other mechanisms are suggested in this frequency band. From about 10–100 Hz, the wind dependence can also be identified under special conditions. In comparison with the higher frequency case, different mechanisms of wind-induced noise are indicated. In the band 1–10 Hz, the wind dependence can be observed in the data, but the basic mechanisms of noise sources within this band are not easily identified. Variations of ambient noise spectra depending on location, hydrophone depth, and sample size are discussed. A recommendation is made for future experiments that will investigate the various mechanisms of wind-induced noise.
Scattering strength derived from shallow water reverberation measurements
Authors: Thiele Rolf
Published: October 2005

Reverberation has been measured together with transmission loss in several areas of the North Sea and the Baltic, using explosive sources. From both quantities the backscattering strength of the water column was evaluated by simply applying the active It is shown that in most cases the backscattering SONAR equation. It is shown that in most cases the backscattering strength becomes range-independent beyond short distances. The backscattering strength therefore appears to be a useful parameterisation of regional and seasonal reverberation and may possibly be applied to determine the range dependence of transmission loss.
Grain shape and sorting effects on the frequency dependence of shear wave attenuation in water saturated sediments
Authors: Brunson Burlie A. , Matthews James E.
Published: October 2005

Laboratory measurements of shear wave attenuation as a function of frequency were made using previously developed ceramic bimorph transducers [B. A. Brunson and R. K. Johnson, J. Acoust. Soc. Am. 68, 1371–1375 (1980)]. Transverse particle motion was excited in three water-saturated laboratory sediments of the same mean grain size but differing in their degree of grain size sorting and grain shape. The sediments included a moderately sorted angular quartz sand; a well-sorted angular quartz sand; and well-sorted spherical glass beads. The attenuation values increased with frequency over the measurement range from 1 to 20 kHz, but exhibited dependencies more complicated than a simple first-power frequency relationship. Comparisons were made with predictions based on a two-component model [R. D. Stoll, Geophys. 42, 715–725 (1977)] using inputs derived in part from laboratory measurements of key sediment properties. Insight into the adequacy of this model to predict attenuation in nonideal sediments, and the importance of using model inputs obtained under controlled conditions was demonstrated. [Work supported by NORDA and NAVELEX 320.]
Electrical stimulation of the eighth nerve in cat: Temporal properties of unit responses in the large spherical cell region of the AVCN
Authors: White M. W. , Merzenich M. M. , Loeb G. E.
Published: October 2005

Single-unit responses to intracochlear electrical stimulation were studied. Responses were highly phase-locked to sinusoidal stimulation at frequencies less than 4 kHz. At any given stimulus frequency, synchronization indexes were greater than those that have been reported for eighth nerve responses to acoustic stimuli. At the onset of a low-frequency (i.e., below 800 Hz) sinusoidal stimulus, firing rate gradually increased over many tens of milliseconds. Rise times were as long as 50–100 ms for low-intensity, low-frequency sinusoidal stimulus bursts. At greater intensities and/or higher stimulus frequencies, the response rise times were considerably shorter. Preliminary results indicate that responses to trains of short-duration biphasic pulses do not exhibit such slow rise times. These results may relate to Eddington's [Ann. Otol. Rhinol. Laryngol. 87 (Suppl. 53), 1–37 (1978)] finding that behavioral threshold increases sharply as the burst duration of a sinusoidal stimulus is decreased. However, threshold is only a weak function of the duration of a train of short-duration biphasic pulses. For sinusoids below 300 Hz, multiple discharges per cycle were common at levels considerably above threshold. [Work supported by NIH.]
Intelligibility of speech with reverberation and amplitude compression
Authors: Nábèlek Igor V. , Koike Kazunari J. M. , Wood W. Scott
Published: October 2005

Modified Rhyme Test (MRT) was recorded in a room with reverberation the reverberation time T = 0.8 s). The “reverberant” speech was submitted to three-channel multiband compression (MBC) in which the compression ratio (CR) in each channel was adjusted on the basis of the dynamic range of speech and the dynamic range of subject's (S) hearing. The processed signal was amplified with individually adjusted frequency responses and delivered to the listeners via a circumaural earphone at the most comfortable levels. Ten sensorineural S's were tested. The mean scores without reverberation, without and with compression were 82.9% and 84.3%, respectively. The reverberation lowered these scores to 51.7% and 48.7%, respectively. While the mean scores with reverberation were significantly different than without it, the effect of compression was not significant. [Work supported by NIH NS 12946.]
Predicting aided speech perception
Authors: Miller James D.
Published: October 2005

The aided listener's potential P for perceiving phonemes and words is taken as the product of the goodness-of-fit F of the aid and the proportion of residual phonemic hearing H. The goodness-of-fit F is the product of the proportion of relevant speech energy that is comfortably audible (A) and the degree to which the aided spectrum is in balance (B) with the most-comfortable listening levels. Residual phonemic hearing H is the product of residual sensitivity S for relevant speech energy and the residual dynamic range D. All variables are weighted by the importance function of the articulation index and range from zero to one. The aided potential P is the product F⋅H which in turn is the product A⋅B⋅S⋅D. The model is applied to 21 ears with cochlear, sensorineural hearing losses aided by their personal aids and again by a speech audiometer. Correlations between scores on the California Consonant Test and P are 0.86 [Supported by NINCDS Grant NS 03856.]
Acoustic privacy in condominium living
Authors: Aziz Javaid
Published: October 2005

There were new demands for acoustical privacy by the condominium owners from the builders of condominiums as condominium living became popular in the 1970's. The condominium owner had different perspective about acoustical privacy than the short-term apartment dweller. The builders were at a loss to understand why there were complaints in some instances even with the best that they could build. The construction improvements, however, are only possible to an economically feasible limit. The concept of background noise as a means of reducing annoyance due to intrusive noise is not well understood by architects and builders. There is a need for defining “comfortable” acoustical privacy in condominiums of which background noise is an integral part. A case is made for ensuring that the finished condominiums would have the background noise level that was built into the “comfortable” acoustical privacy analysis.
Comparative results of sound isolation measurements
Authors: Taibo Lucía , de Dayan Hilda Glasserman
Published: October 2005

For many years, several authors have been concerned with the development of simplified procedures for the determination of sound isolation in buildings, specially conceived for their application in legal control of acoustical requirements. Obviously, the use of the well-known standardized methods demands a considerable amount of time and the participation of highly skilled operators that is normally impractical during quick checks. In our country, the idea of finding a short test method to be introduced into standardization, has been pursued for many years. Recently, a new simplified technique has been proposed [Taibo-Dayan, Proceedings Internoise 80 (775–778)] based in the assumption of an average correction factor due to the absorptive characteristics of the receiver. In the present work, results obtained by the application of this method to real situations, as well as the widespread simplified technique proposed by Schultz in the United States (tentative ASTM standard E 597) and a German proposal due to Eisenberg (Report P.T.B. Braunschweig, 1978) have been compared. Numerical results are given and some tentative conclusions are outlined.
Improvement in impact insulation ratings of common floor/ceiling assemblies in multi-family dwellings with standard floor coverings
Authors: Rosen Stanley M.
Published: October 2005

Improvement in the field-rated impact insulation class [FIIC] was measured for several common floor/ceiling assemblies in existing multi-family buildings utilizing several standard grades of carpet pad and various vinyl products. Testing included determination of FIIC ratings with existing floor coverings and with other, more effective, floor coverings including ordinary cushioned vinyl, thickly cushion-backed vinyl, and vinyl products with fiber board and particle board underlayment. Test results indicate that a significant improvement in the FIIC ratings of existing vinyl covered floor/ceiling assemblies can be achieved by the superposition of an appropriate cushioned vinyl on top of the existing standard vinyl. The test results also indicate that a significant increase in FIIC ratings of existing carpeted floor/ceiling assemblies can be achieved by appropriate selection of new pad and carpet. Test data from measurements performed in accordance with ISO recommendation R140 are presented in the paper for several representative configurations.
Multifamily party wall noise insulation by single metal and wood stud walls
Authors: Campanella Angelo J.
Published: October 2005

Residents of apartments with a single-steel stud party wall were satisfied with its noise insulation. The residents of apartments with a single wood stud wall were displeased to the extent that the owner is being forced to improve the wall's noise insulation. The field sound transmission loss (FTL) of the steel stud wall and the wood stud partition wall between apartment units was measured. The equivalent STC values for these two walls were calculated from these data. The wood stud wall was found to have an equivalent STC 37 value, and the steel stud wall an equivalent STC 48 value. These STC values were found to be in basic agreement with those obtained by laboratory tests on similar walls. It was concluded that for single stud walls, wood studs are an inferior sound insulator as compared to steel studs. The reason for this is believed to be that the steel studs act as their own resilient clips. This makes the steel stud structure much more cost effective than wood stud construction for single stud walls. It was recommended to the owner that he construct an additional stud wall set apart from the existing wood stud wall to achieve acceptable noise insulation.
Wide-angle propagation in inhomogeneous fluids and elastic solids using perturbation methods
Authors: Wales Stephen C.
Published: October 2005

Wave propagation in range- and depth-dependent environments remains an important area of interest in acoustic modelling. The difficulty is that in the most general cases energy flows in opposite directions, thus requiring that the medium be considered in its entirety to obtain a solution. However, in many cases of interest energy flows predominately in one direction, permitting the use of range-incrementing procedures. These cases may often be characterized as involving weakly inhomogeneous media. This paper presents an approximate solution to the elastic displacement potentials for propagation through an inhomogeneous layer, using a Born-type perturbation expansion. In the limit of an infinite number of sublayers and forward scattering is this approximation can be converted to a Rytov-type approximation. Rytov approximations are credited with a superior range dependence. Neither approximation carries the narrow-angle restriction of models based on the parabolic equation and both can handle range-dependent environments. Fluids are handled by simply specifying no shear effects. Two fluid models have been developed using these approximations. The relative merits of the two approximations are discussed and demonstrated using the two models. [Work supported by the Naval Research Laboratory's Edison program.]
Cylindrical waves in transversely isotropic media
Authors: White J. E. , Tongtaow Chalermkiat
Published: October 2005

Because of fine layering, many sedimentary rocks can be characterized as transversely isotropic, possessing an axis of symmetry perpendicular to the layering. The many kinds of measurements made in fluid-filled holes drilled parallel to this axis prompted this study of axisymmetric cylindrical waves. The literature shows how such waves in an isotropic solid can be expressed in terms of a compressional potential or a shear potential. This paper shows that in a transversely isotropic medium, particular combinations of these potentials are needed simultaneously, yielding either a quasicompressional or a quasishear wave. The expressions are used to compute the transient response of an acoustic logging tool. The speeds of refracted compressional and shear waves agree with the speeds of plane waves traveling along the axis of symmetry. Dispersive waves in the fluid annulus yield further information about the elastic constants of the solid. The potentials also portray the radiation of elastic waves from a point force or from a transducer on the surface. [Work supported by The Integrated Geophysics Project.]
Quasienergy conservation principle formulation for the generalized wave equation with losses
Authors: Akers G. R.
Published: October 2005

The normal conservation of energy principle exists in the form ∇⋅F + St = 0. Whereas in the case of the generalized equation of motion for wave propagation in a medium incorporating energy losses, this strict formulation of the conservation law does not hold, one may obtain an extension of this law by recasting the equation in the “quasiconservative” form ∇⋅F + St + B = 0, where B is identified as the generalized loss function −L and S is written in terms of the temporal and spatial displacement derivatives of the system.
Laser-generated ultrasonic waveforms in metals
Authors: Hutchins D. A. , Dewhurst R. J. , Palmer S. B. , Scruby C. B.
Published: October 2005

A Q-switched, Nd:YAG laser has been used to generate elastic waves within aluminum and mild steel disks. A single 24-ns pulse from the laser irradiated one face of each disk, and acoustic displacements were detected at the other face following propagation through the substrate. A capacitance transducer was used as the detector, providing undistorted displacement waveforms over a wide bandwidth. The displacement waveform depended markedly on the irradiation conditions. At low laser power densities, such that generation occurred primarily by thermoelastic expansion, a common waveform was produced whose amplitude varied linearly with optical energy. At higher power densities in the presence of material ablation, the longitudinal amplitude increased substantially whereas that of the shear decreased. Wave propagation theory in a plate has been applied to the problem, and theoretical waveforms in good agreement with experiment have been produced; this leads to conclusions concerning the nature of the acoustic source formed by laser irradiation.