bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound amplification from controlled excitation reactions
Authors: Bass H. E.
Published: October 2005

The possibility of an acoustic analog of a gaseous molecular laser has been investigated theoretically. It has been found that the mechanisms which lead to relaxation absorption in a gas can, in the presence of vibrational energy level populations far from equilibrium, give rise to sound amplification. This results from the fact that the relaxation times decrease with temperature; hence, as the sound wave causes the local temperature to increase, energy in the vibrational modes is converted to translation rapidly, giving rise to a further temperature rise. The opposite effect occurs when the sound wave causes the local temperature to decrease. For illustrative purposes, a 90% CO–10% H2 numerical example has been developed. This example demonstrates that sound amplification should be experimentally observable using a laser as the source of vibrational excitation.
Measuring the properties of small samples of superheated liquids
Authors: Apfel R. E.
Published: October 2005

In order to measure the properties of greatly superheated liquids, it may be necessary to use very small samples (say 5 μl) suspended in an immiscible “host” liquid. It has been demonstrated that a droplet of one liquid can be levitated in a host in which an acoustic standing wave has been established by balancing the buoyancy force by an acoustic force F due to radiation pressure. The force F is proportional to the product of the acoustic pressure and the pressure gradient (F = KPdP/dz); the proportionality coefficient K predicted by theory is a known function of the densities and sound speeds of the two liquids. We can measure K for a sample of unknown properties by a comparison method in which first a droplet of known properties and then the sample are levitated at the same position in a “host” of known properties. Field conditions needn't be measured. Results of initial experiments are reported and the limits of applicability of the method are discussed. [This work supported by the U. S. Office of Naval Research.]
Ultrasonic absorption and kinetics of proton exchange in solutions of 5′ ADP and 5′ ATP
Authors: Lang J. , Yiv H. , Zana R.
Published: October 2005

The variation of α/f2 (α = ultrasonic absorption coefficient, f = frequency) versus the pH for aqueous solutions of adenosine 5′-diphosphate (5′ ADP), goes through two maxima at pH 3 and 5, respectively. For aqueous solutions of adenosine 5′-triphosphate (5′ ATP) the excess absorption shows a maximum at pH 3 and a shoulder at around pH 5. The excess absorption observed for 5′ ADP and 5′ ATP at around pH 5 seems to be due to a bimolecular proton exchange reaction between the protonatable nitrogen atom of the base moiety and the secondary phosphoric acid function. The excess absorption observed at pH 3 for both nucleotides seems partly due to a bimolecular proton exchange between the protonatable nitrogen atom of the base and the primary phosphoric acid function. At above pH 6, 5′ ATP solutions show an excess of ultrasonic absorption relatively to 5′ ADP solutions. This excess of absorption is attributed to the binding of the Na+ counterion to the triphosphate moiety of 5′ ATP.
Scattering of acoustic point source fields by sinusoidal and by random surfaces
Authors: Davies Huw G.
Published: October 2005

Estimates are obtained for the pressure field reflected from both sinusoidal and also random rough surfaces when the surfaces are insonified by a high-frequency, omnidirectional point source. A geometric acoustics or ray-tracing approach is taken together with the assumptions that there is no shadowing of the surface, and that each ray undergoes a single reflection. A stationary phase approximation of the Helmholtz integral is used to estimate the field associated with each ray. The emphasis of the paper is on accounting for the phase differences, that is, the interference effects, between the possibly very many geometric rays from source to surface to receiver.
New approach to scattering by random media and interfaces. I. General method
Authors: Middleton David
Published: October 2005

A promising approach has been developed for treating acoustic (and EM) scattering by random media and interfaces, which permits statistically “exact” solutions to the typical integral equations determining the scattered fields and received waveforms. The scattering mechanism is expressed as the sum of independent random processes in space and time whose structural details embody the physical features (e.g., cross sections, reflection coefficients, path delay, Doppler, frequency selectivity, etc.) of the acting scattering elements, and whose statistics (e.g., moments, covariances, spectra, etc.) constitute, in any case, the observables of the scattering process. This mechanism is then applied as the forcing term in the Langevin equations governing propagation. These are readily solved (in the linear cases) by conventional or diagrammatic methods, for weak or arbitrarily strong scattering. In general, for the weak-scatter conditions in the ocean, the covariance and spectra of the received process consist of three contributions: a specular term (k=0); a purely random “specular-point” or Poisson scatter component (k=1); and the continuum scatter contribution (k=2) of earlier “classical” approaches. Other implications for underwater sound scattering are also discussed here, and in the companion paper (II) below. [Work Supported by the Naval Sea Systems Command.]
New approach to scattering by random media and interfaces. II. Active underwater acoustic channels
Authors: Middleton David
Published: October 2005

The general method of paper I above is systematically applied to the characterization of active underwater acoustic channels, in an isovelocity ocean. Expressions for the second-order statistics of the received scattered field are obtained, which, apart from a possible coherent term (k=0), exhibit a combination of the Poisson [or Faure-Olshevskii-Middleton (FOM) model] contribution (k=1), and the earlier continuum, or “classical” component (k=2). Unlike all earlier “classical” scatter theories, the dynamical effects of Doppler are explicitly obtained, from the ensemble of appropriate “Dopplerized” wave equations, e.g., Langevin equation. Random-path delays produce the expected random phase modulation, as do the various Dopplers, but unlike the former the latter have variances quadratic in time. Because of this, the scattering medium, even when stationary, progressively destroys the coherence of the injected signal. The continuum component (k=2) of the medium itself may be described by delay-spread and Doppler-spread “cells” which are now correlated (i.e., non WSSUS), unlike the Poisson term (k=1), which is WSSUS. Other channel features are considered, including conditions for validity of the FOM models, and the role of surface interactions. [Work supported by Naval Sea Systems Command.]
Scattering of broad-band ultrasonic beams from circular disks
Authors: Adler Laszlo , Lewis D. K.
Published: October 2005

In an attempt to develop models for nondestructive testing of flaw characterization we have simulated “flaws” by using metal circular reflectors in water. A broad-band ultrasonic beam was incident on the reflectors. The scattered wave amplitudes were measured as a function of frequency for fixed angles and as a function of angles for several frequencies. In our previous work [Laszlo Adler and H.L. Whaley, J. Acoust. Soc. Am. 51, 881 (1972)], the frequency distribution of the scattered sound wave was related to the size and orientation of the reflector by an approximate theory. This theory assumed that the wavelets originating from the extreme edges of the reflector will interfere. Now we have adopted a theory from the diffraction of electromagnetic waves by aperture [Keller, Appl. Phys. 28, 426 (1957)]. An expression for the diffracted amplitude was calculated as a function of frequency and angle for several reflector sizes. The result compares favorably with our experiments. [This research was sponsored by the Center for Advanced NDE operated by the Science Center, Rockwell International, for the Advanced Research Projects Agency and the Air Force Materials Laboratory under Contract F33615-74-C-5180.]
Adenyl cyclase in the guinea pig cochlea
Authors: Kerr T. P. , Schacht J.
Published: October 2005

Cellular functions regulated by adenyl cyclase include protein synthesis and secretion, membrane permeability, and active transport of ions. We assayed cochlear adenyl cyclase histochemically as well as in tissue homogenates in vitro with the specific substrate adenylyl imido-diphosphate (AMP-PNP). Adenyl cyclase activity was demonstrated in the plasma membranes of the inner sulcus cells, the interdental cell of the limbus epithelium, and in the infoldings of the mesothelial cells covering the perilymphatic surface of the limbus. The reaction with AMP-PNP appears heaviest in the basal turn, and is sparse or absent in the apical turn, and is enhanced by sodium fluoride. Little or no enzyme activity was found in the organ of Corti or the lateral wall of the cochlear duct. Adenyl cyclase may be of significance for the control of physiological inner-ear function and may be involved in the mediation of the ototoxicity of ethacrynic acid, which is an inhibitor of the enzyme. [Supported by NIH-NIEHS Contract NO 1 ES-2-2110 and NIH Program Project Grant 05785.]
Description of the transfer characteristics of the cochlear microphonic
Authors: McPherson D. L.
Published: October 2005

The transfer characteristic curves of the CM were constructed by measuring the cochlear potentials inside the scala media (SM). The transfer curve was constructed by measuring the input-output of the cochlear potentials (CM and SP) and plotting the magnitude of the cochlear potentials for + CM and − CM as a function of pressure change (dynes/cm2) of the input stimulus. Both amplitude and phase were measured in all four turns of the guinea pig cochlea. Results are based upon data from 22 animals. Graphs were constructed showing the gain of the biological system (in decibels) as a function of phase shift. The transfer characteristics changed as a function of recording site along the scala media (SM). When comparing a theoretical waveform to actual waveforms, the transfer characteristic at a given point within the SM agrees with experimental data. The gain-phase plot demonstrated the ability to view, as a single function independent of frequency and electrode placement, the relationship of the cochlear potential to the auditory stimuli.
Intensity-dependent changes in the cochlear summating potential following electrical stimulation of the crossed olivocochlear bundle
Authors: Gans Donald P.
Published: October 2005

Pairs of tungsten electrodes were placed in scalae vestibuli and tympani of either the first, second, or third cochlear turns of 21 guinea pigs. For summating potential (SP) measurements, the outputs of the two electrodes were subsequently added (AVE SP) and subtracted (DIF SP) so that various components of the SP could be analyzed. The crossed olivocochlear bundle (COCB) was stimulated with trains of 40 biphasic pulses presented at a repetition rate of 1/sec. The sequence used for collecting SP data during COCB activation consisted of presenting a 20-msec tonal stimulus with nearly instantaneous rise-fall characteristics to the right ear 10 msec after the final shock pulse. The relative change in several SP components was strongly dependent on stimulus intensity, whereby the greatest COCB influence was achieved for those SP responses recorded at low sound-pressure levels. If follows that since synapsing to the fibers belonging to the COCB is largely limited to the outer hair cells, it can be theorized that the decreased COCB effect at high sound-pressure levels resulted from the added contribution to the SP by the inner hair cells which are not affected by COCB stimulation. [Supported by a grant from the NINDS.]
Relation between cellular excitation and inhibition and averaged evoked potentials in the inferior colliculus of the rat
Authors: Harris D. M. , Rosenfeld J. P.
Published: October 2005

Single and multineuronal response patterns in the form of peri-stimulus-time histograms (PSTH) and simultaneously averaged evoked field potentials (AEP) were investigated for correlations between PSTH and AEP waveforms. Concomitant changes in both waveforms were also studied as a function of stimulus frequency and recording location. A short latency initial excitation exhibited by most neurons was temporally correlated with either the slope or peak of the initial negative deflection of the AEP. This was usually followed by a brief cellular inhibition and a transient positive deflection of the AEP. A sustained potential shift (+ or −) was often observed in the AEP and correlated with the duration, polarity, and location of local cellular excitation and inhibition. Intracellular data as reported in the literature indicate that the interpretation of field potentials as summated postsynaptic potentials is consistent with these results.
Frequency-following response in subjects with complete unilateral hearing loss: evidence for two generators
Authors: Daly D. M. , Roeser R. J. , Moushegian G.
Published: October 2005

The use of auditory evoked response averaging in assessing brainstem integrity depends principally on analysis of the early components, waves I-V of Jewett, and the frequency-following response (FFR). This experiment examines effects of complete unilateral hearing loss on FFR. We recorded Cz-Al and Cz-A2 responses evoked by monaurally and binaurally presented tone bursts (500 Hz, 14 msec in duration) from subjects with normal hearing in each ear and from subjects with complete unilateral hearing loss. Monaural stimulation of either ear in normal subjects, and of the unimpaired ear in hearing-loss subjects evoked larger responses ipsilaterally than contralaterally. Stimulation of the impaired ear in hearing-loss subjects evoked no response. Binaural stimulation in normal subjects evoked Cz-Al and Cz-A2 responses of equal amplitude, each larger than the ipsilateral monaural response. Binaural stimulation in hearing-loss subjects evoked responses equivalent to those obtained monaurally. The results support the hypothesis that there are at least two, separate, compact neural generators for FFR. [Supported in part by NIH/NINDS Grant NS 02098.]
Sound propagation in shallow water off Wallops Island, Virginia
Authors: Stallard J. M.
Published: October 2005

The propagation of sound in a relatively constant 40-foot-deep region of the Atlantic Ocean off Wallops Island, Virginia, is modeled using both image and normal-mode theories. The model is compared to observations of signal level over a frequency range of 40–10 000 Hz (0.32⩽H/λ⩽80) and at distances out to 2000 yards (r/H=150).
Potential for valve-induced acoustic fatigue in piping systems
Authors: Sawley Roger J. , Scharton Terry D.
Published: October 2005

In recent years, as sources of noise in piping systems have become more powerful, the potential for structural fatigue induced by intense acoustic fields in such systems has increased. This paper examines the potential for such a problem in those cases where the acoustic field is produced by the passage of a gas flow through a control valve.
Folded semi-infinite waveguide
Authors: Hillery H. V.
Published: October 2005

An experimental study has been made of the propagation of low-frequency longitudinal sound waves along parallel, non-collinear, straight solid aluminum rods joined together at the ends to form a folded waveguide. Results show that tone bursts propagated outward on the input section of the waveguide successively reverse direction of propagation at the joints to enter succeeding rods. No reflections are produced if the joints are impedance matched to the characteristic mechanical impedances of the rods. Thus a very long echo-free waveguide can be provided in a relatively small space. Since the impedance match at the joints is independent of frequency, the folded waveguide can be used to obtain long time delays of broad-band audio signals. Also, in a given space, the folded waveguide allows independent measurement at lower frequencies than is otherwise possible of the amplitudes and phases of narrow-bandwidth tone-burst signals incident upon, transmitted through, and reflected from a target attached to the waveguide. [Research supported by the National Science Foundation.]
Use of impulsive sound in acoustical modeling
Authors: Lyon Richard H. , Cann Richard G. , Klinkowstein Robert J.
Published: October 2005

Impulsive sound has several advantages when used for acoustical scale modeling. These include elimination of the need for anechoic treatment to the laboratory walls, the identification of major paths of propagation, and the ability to correct for excess attenuation due to nonideal properties of the medium. When the impulsive sound is generated by a spark, the generation of the sound wave is inherently nonlinear, tending to follow the rules for blast wave production rather than the generation of sound by heat addition. Over certain distances and range of frequencies, the propagation is nonlinear, and a simple modification to geometric spreading appears to suffice. In the complementary linear regime, ordinary absorption rules appear to be appropriate. The conclusion from our studies is that the spark source is a useful and valuable sound source for modeling work in spite of problems of nonlinear propagation, electromagnetic interference, and high-voltage control. [Work supported by RANN program, NSF, and Department of Airports, City of Los Angeles.]
Some observations with ultrasonic assisted filtration
Authors: Fairbanks H. V.
Published: October 2005

The influence of ultrasound upon the filtration of oil slurries containing particles ranging in size from 1 to 30 μ were investigated. The ultrasound was introduced into the filtrate media applying sonic intensities ranging from 1 to 6 W/cm2 at a frequency of 20 kHz. A significant increase in the filtration rate was obtained. It was also found that the particles in the size range of 2–4 μ were found to have coagulated beneath the filter membrane even though the membrane contained many flow channels larger than 4 μ in diameter.
Effects of intervocalic consonant characteristics on vowel-to-vowel coarticulation
Authors: Klich R. J.
Published: October 2005

Two male subjects produced VCV syllables that were composed of all possible combinations of the vowels /i,a,u/ and the consonants /p,b,t,d,f,v,s,z/; each syllable was repeated three times. The second formant frequencies of the vowels were measured in the steady state and at the consonant boundaries from wide-band spectrograms. The most obvious finding was that both the steady-state and boundary frequencies were lower with voiced consonants than with voiceless consonants. In addition, the extent of the transition for voiced consonants was greater than for voiceless consonants, particularly in symmetrical VCV syllables. These findings concerning voicing probably are associated with the differential articulatory adjustments required for making the voicing contrast. Fricative and alveolar consonants tended to elevate the steady-state frequencies of the vowels, but these effects were not as marked as those for voicing. Place of articulation had the greatest effect on the extent of both the VC and CV transitions. Differences between subjects and for particular vowel contexts probably are associated with differences in the extent and nature of articulatory adjustments required for the production of VCV syllables.
Pitch of voiced and whispered vowels
Authors: McGlone R. E. , Manning W. H.
Published: October 2005

The sound source for whispered vowels is considered air flow turbulence rather than pulsated flow from vocal-fold vibrations. These latter vibrations usually are considered to create the sensation of pitch. Yet, there is some evidence [G. J. Harbold, J. Acoust. Soc. Am. 30, 600 (1958)] that vowels maintain the same pitch relationship to each other whether voiced or whispered. The purpose of this study was to determine and compare the pitch ratings of vowels produced by both sound sources. Four male speakers recorded vowels /ɪ,i,u,ɔ,æ/ in hV syllables both whispered and vocalized. All possible syllable pairs were edited together within the same condition; whispered and voiced were not mixed. These pairs were played to 40 judges who indicated which of the pair had the higher pitch. From these judgments, rankings from highest to lowest pitched vowels were made. Differences occurred between voiced and whispered vowels of this study, and between voiced of this study and Harbold's voiced; but whispered vowels of the two studies were extremely similar with rho of 0.9. Results suggest that whispered vowels have distinct pitch-perceived qualities.
Fundamental frequency characteristics and perceived age of adult male speakers
Authors: Horii Y. , Ryan W. J.
Published: October 2005

This study investigated acoustic correlates of aging in the voice. In particular, the mean fundamental frequency (f0) and f0 variability of 57 adult male speakers obtained by a direct age estimation experiment. The results showed that the mean f0 was positively correlated with the perceived age while the f0 variability was not significantly related to the perceived age of the speakers. The magnitude of the correlation between the perceived age and the mean f0 was significantly greater than between the chronological age and the mean f0, suggesting that the listeners tended to associate perceived aging with higher average f0. The correlation increased significantly when only those speakers upon whose perceived age the listeners closely agreed (regardless of the accuracy of the estimates) were examined.
Comparison of intelligibility with duration and pitch control in the speech of deaf children
Authors: Monsen R. B. , Leiter E. R.
Published: October 2005

Two measurements of prosody were made from the connected speech of 37 hearing-impaired and six normally hearing adolescents: (1) average word duration, and (2) amount of variation in fundamental frequency. The intelligibility of the subjects was measured by scoring the performance of 50 normal listeners. A significant (negative) correlation was found between average word duration and intelligibility, and a slightly higher (also negative) correlation between the duration of function words and intelligibility. In contrast, linguistically appropriate pitch control, as measured by the amount of F0 variation, does not correlate with speech intelligibility. That is, the speech of both intelligible and highly unintelligible speakers may exhibit a large amount of F0 variation. The amount of F0 variation is probably an inadequate measure of pitch control, since it takes into account neither the appropriateness of F0 variation nor any of the following three deviations common among deaf talkers: (1) F0 quaver, (2) F0 discontinuity, and (3) diplophonia. [Supported by NINDS Grant NS 03856.]
Temporal summation and decay in hearing
Authors: Irwin R. J. , Kemp S.
Published: October 2005

The growth and decay of auditory sensation with time were studied by comparing the detectability of brief tone bursts with that of brief tone gaps. A two-alternative forced-choice procedure showed that the percentage of correct detections of bursts was greater than the percentage of correct detections of gaps of equal duration. This result held for bursts and gaps of 25- to 200-msec duration in a 1000-Hz tone at two different power-to-noise ratios. The results were compatible with a theory of temporal summation in which a transformation of the sound is weighted by a decaying exponential function with a time constant of 5 sec−1. The greater detectability of bursts than gaps also means that the growth of auditory sensation is faster than its decay.
Modeling implications of measurements on excised larynxes
Authors: Baer Thomas
Published: October 2005

Results of experiments with excised canine larynxes are examined within the framework of a two-mass model of the larynx, and the implications of the results for laryngeal modeling in general are considered. Sketches of glottal shapes were constructed on the basis of detailed measurements during a glottal cycle [J. Acoust. Soc. Am. 55, S79 (1974)] and during static experiments. A two-section model was fit to these sketches, and the resulting fits were used to estimate values for some parameters of the two-mass model. To the extent that analysis was possible, the aerodynamic equations of the model were found to be adequate. However, the design of the mechanical system, consisting of two coupled masses capable of only horizontal excursions, was not able to account for some experimental results. A description of the vibrations in terms of a propagating membrane or surface wave on the vocal-fold walls as well as string vibrations of the vocal ligament is proposed. Representation of these phenomena is discussed.
Low-noise chambers for research in auditory physiology
Authors: Vér István L. , Brown Robert M. , Kiang Nelson Y. S.
Published: October 2005

The new experimental facilities for the Eaton-Peabody Laboratory of auditory research required an environment unusually free of ambient acoustic, vibratory, and electric noise so that small electric signals in response to low-level sounds can be measured. In specifying the acoustic design goals, one had to consider that spontaneous activity in the cat's auditory nerve (an important topic for the projected research) can be distinguished from that generated by low-level acoustic noise (Wiederhold and Kiang, 1970), As constructed, the ambient noise in the chambers with the ventilation system operating is well below the human threshold of hearing. The noise reduction at 250 Hz is almost 80 dB, and above 500 Hz exceeds 90 dB. The ambient vibration level at the experimental table, on which the animals are placed, are below −120 dB re 1 g. This paper deals with the problems that arose in the setting of criteria, the design, the construction and the performance evaluation of the chambers. [Supported in part by NIH.]
Modulation of a small-signal wave by a finite-amplitude wave of lower frequency
Authors: Schaffer Mark E. , Blackstock David T.
Published: October 2005

When a plane finite-amplitude wave of frequency f1 interacts with a plane small-signal wave of higher frequency f2, side-bands at frequencies f2±nf1 are produced while the amplitude of the f2 signal is reduced. Two models have been used to predict the spectrum. The first is frequency modulation theory [see, e.g., R. G. Pridham, J. Acoust. Soc. Am. 55, S50(A) (1974)]. The second is F. H. Fenlon's theory, slightly modified, for radiation from a two-frequency source [J. Acoust. Soc. Am. 51, 284–289 (1972)]. Measurements were carried out in air in a 96-ft progressive-wave tube. The properties of the two signals at the source were as follows: f1=1 kHz, SPL1=140–150 dB (re 0.0002 μbar), f2=4–7 kHz, SPL2 < 100 dB. The measured amplitudes of the weak signal and its sidebands agreed more closely with the modified Fenlon theory than with the FM theory. Attempts to nullify the weak signal by the interaction resulted in amplitude reductions as great as 40 dB. [Work supported by AFOSR and ONR.]
Traffic noise versus roadway surfaces
Authors: Wisleder Dean E. , Johns Jesse
Published: October 2005

Research involving roadway surfaces has generally been directed toward weather resistance, durability, economy, use of local materials, skid resistance, and visibility. Tire noise has been added to this growing list Roadway surface generates vehicle noise in two ways. Magna roughness causes the unsprung weight of the vehicle—the wheels and axles—to vibrate. In severe cases it can cause the sprung weight to vibrate too, but such a surface is generally unsatisfactory and needs repair. Macro roughness on surface texture ranges from slick smooth to the pebbly surface caused by 34-in. aggregate, This report illustrates the influence macro roughness has on skid resistance and tire noise. It describes a test in which all noise generated by two-way traffic is measured as it travels over an I-11, high-density surface, a widely used standard surface in Illinois, and a promising new open-graded plant mix wearing course. Spectra of L levels from both surfaces were determined for three 30-minute tests. The part played by tire noise at each L level is evident and consistent from test to test.
Development and description of the American reed organ
Authors: Schulz Russell E.
Published: October 2005

Although the reed organ is a primary artifact of 19th-century home life in America, heretofore it has received very little serious study. This paper surveys the evolution of the instrument, from its beginnings through its characteristic stages during the late 19th century, especially as represented by the Mason & Hamlin Cabinet Organ. The American setting is described briefly, and then the instrument is placed in that setting. European predecessors are surveyed. The characteristics of the typical American reed organ are investigated. Strengths and weaknesses of the tone as produced by free reeds are discussed, along with mechanical stops used to modify the basic sound. The paper relies solely on 19th-century sources for its primary references.
Monaural loudness adaptation at low sensation levels in normal and impaired ears
Authors: Margolis R. H. , Wiley T. L.
Published: October 2005

Monaural loudness adaptation was measured in subjects with normal hearing sensitivity and with noise-induced sensorineural hearing loss using a homophonic delayed-balance technique and the Method of Constant Stimuli for 500- and 4000-Hz signals at 15 and 25 dB SL. The interstimulus interval (ISI) between adapting and comparison stimuli was 10 or 400 msec and adapting stimulus duration was 1, 30, or 60 sec. No significant loudness adaptation occurred under any conditions for normal-hearing listeners. There was no apparent effect of adapting signal duration, frequency, sensation level, or ISI. Subjects with sensorineural hearing loss demonstrated small amounts of loudness adaptation. There was no effect of adapting signal frequency, even though hearing sensitivity was normal at 500 Hz and abnormal at 4000 Hz.
Introductory remarks on arrays for measurement of complicated wave fields
Authors: Cook Richard K.
Published: October 2005

We examine methods for sorting out and measuring the distributions of strengths and propagation directions for the component waves in spatially complicated wave fields. Such measurements are needed in atmospheric and underwater sound, in seismology, and for electromagnetic microwaves. For example, the diffuseness of the sound field in a reverberation chamber needs to be measured and described in terms of its component plane waves. The distributions might not be stationary in time, particularly when moving vanes are employed. This measurement art seems to require the use of geometrical arrays of phased transducers. Quasiholographic techniques, such as beam formation and synthetic aperture, are used for comparison of the phases and time delays at the various locations in the array. The distributions are then derived from the comparison and may be displayed with optical techniques. The invited papers of this session describe the present state of this difficult art.
Acoustic scattering of finite beams by simple geometrical bodies
Authors: Fiorito R. , Gaunaurd G. , Madigosky W.
Published: October 2005

A finite plane acoustic beam 5 in. in diameter at a frequency of 15 MHz is used to spot-insonify various simple geometrical shapes (i.e., cylinder, sphere, plates) both at normal and oblique incidence in a water tank. Echo levels are measured in the backscattered direction. Since a finite aperture transducer is used to both send and receive the signals, suitable Fresnelzone, absorption, and spreading corrections are made to compare measurements to theoretical predictions for the sonar cross sections. The sonar cross sections for the finite spot insonification cases of interest are developed from the Rayleigh-Kirchhoff integrals by means of the Kirchhoff approximation. The resulting expressions contain contributions from the specular reflection point, the (shadow) boundary of the spot, and interactions of these two. As expected, at high frequencies, the specular reflection contribution is dominant and good agreement between it and the measurements is found. [This work was partially supported by the Naval Sea Systems Command-0342.]
Multiple scattering between a cylinder and a plane
Authors: Bertrand J. C. , Young J. W.
Published: October 2005

Experimental measurements of the backscattering of a plane acoustic wave by a rigid cylinder parallel to a perfectly hard plate are compared with theoretical calculations. Two sets of calculations, one which includes the effects of multiple scattering between the cylinder and the plate and one which ignores these effects, were performed. The measurements were done in fresh water using a 2-in. diameter solid steel cylinder at various distances from a steel plate. The frequency of the incident wave was varied from 50 to 100 kHz. Comparisons between the theories and experiment were made both for the case of the cylinder in front of the plate and for the case of the cylinder behind the plate. The results confirm that multiple scattering effects should be included in these scattering calculations.
On the classification of underwater acoustic signals. I. An environmentally adaptive approach
Authors: Deucer L. M. , Middleton D.
Published: October 2005

Environmental conditions and geometries have a pronounced effect upon the signals received as scattered underwater acoustic waveforms. The use of these environmental factors is important. However, these factors are often ignored or at best are introduced indirectly in the formulation of composite hypothesis testing when analyzing the received signals and classifying causes of the scattering. Here we develop a methodology which permits one to introduce estimates of the current environmental state (i.e., certain environments and geometries) in order to adapt the classification algorithm to the situation. The pertinent features of statistical-physical models of the medium (as proposed by Middleton, for example) are useful guides to the experiments needed for the definition of these environmental states. The implications of an environmentally adaptive approach are discussed, and procedures for estimation, feature extraction, and feature selection are presented. [Work supported by the Naval Sea Systems Command.]
Acoustic observation of density layers in the ocean via biological enhancement
Authors: Fisher F. H. , Squier E. D.
Published: October 2005

Multiple thin layers have been observed acoustically from depths of 90 to 300 m with an 97.5-kHz narrow-band (1°) echo sounder mounted at the bottom of the R/V FLIP when it is in the vertical position. These layers are observed because individual biological scatterers populate density layers. The layers are less than 45 cm thick and probably less than 20 cm. Target strengths of the scatterers as a function of depth will be presented. These observations have been made at 120° W, 31° N and near San Diego. [This work was supported by the Office of Naval Research.]
Discharges of auditory nerve fibers in the alligator lizard in relation to basilar papilla morphology
Authors: Turner R. G. , Nielsen D. W. , Teas D. C.
Published: October 2005

In the ventral region of the basilar papilla of the alligator lizard (Gerrhonotus multicarinatus) hair cell orientation is unidirectional, in the dorsal region, bidirectional. On the basis of differences in the shape of tuning curves, the auditory nerve fibers have been categorized into a low (CF < 1 kHz) or high (CF > 1 kHz) frequency group; these groups have been associated with the ventral and dorsal regions, respectively [Weiss et al., J. Acoust. Soc. Am. 55, S84 (1974)]. In the present study, action potentials were recorded from single high- and low-frequency fibers in response to condensation and rare-faction clicks, filtered clicks, and tone bursts. The discharge patterns of high- and low-frequency fibers depended upon stimulus polarity. High-frequency fibers were categorized as type 1 and type 2. The response of a type 1 fiber to a stimulus of one polarity was the same as the response of a type 2 fiber to that simulus with opposite polarity. The two response categories for high-frequency fibers and the lack of equivalent categories for low-frequency fibers appear related to the bidirectional and unidirectional orientations of the hair cells. [Work supported by NIH grants NS07287, NS06459, and NS05475.]
Relationship of SPL, CM, and umbo displacement under free-field closed bulla conditions in guinea pig
Authors: Cook R. O. , Konishi T. , Hamm C. W. , Yankwich A. H.
Published: October 2005

Continuous measures of sound pressure level at the tympanic membrane, displacement of the umbo, and resulting cochlear microphonic were obtained from anesthetized, immobilized guinea pigs for the 700 Hz–10 kHz frequency band. Sound pressure levels were varied from 55 to 80 dB, to insure amplitude linearity of the CM. Umbo displacement was measured with a fiber optic device capable to 1-Å resolution and 40-kHz frequency response. At frequencies below 1.5 kHz, the displacement amplitudes agree well with extrapolations from previously reported measures obtained at higher sound pressure levels but the slope of the frequency response curves obtained above 1.5 kHz for constant SPL is less than that of previously reported curves acquired by capacitive probe techniques. Low-frequency relationships between SPL, umbo displacement, and basal turn CM obtained by differential electrodes were also shown.
Relationship of ossicular chain displacement and CM resulting from stimulation with direct contact piezoelectric drivers
Authors: Cook R. , Konishi T. , Hamm C. W. , Yankwich A. H. , Royster L.
Published: October 2005

Frequency-response curves (300 Hz–10 kHz) relating displacement of PZT driver assembly tip when driving the ossicular chain of anesthetized guinea pigs at the umbo and resulting CM were obtained. These measures were compared with similar measures of umbo displacement, CM and SPL obtained when the tympanic membrane of the same animals were driven in the normal acoustical manner. The effect on CM of driving different parts of the ossicular chain were compared as well as displacement of the umbo when the incudo-stapedal joint is driven. Displacements delivered to the incus just behind the incudo-stapedal joint were found to produce on the order of 10 dB greater CM than equal displacement delivered at the umbo. The apparent necessity for an ossicular chain “DC” offset for production of maximum CM at a specific displacement level when using direct ossicular chain contact methodologies is discussed. Oscilloscopic displays of PZT driver tip displacement pattern for complex waveforms and resulting CM are shown.
Speech discrimination derived from guinea pig CM initiated by ossicular chain coupled piezoelectric drivers, by hearing airs, and by conventional acoustic presentation
Authors: Cook R. O. , Thomas W. G. , Konishi T. , Hamm C. W. , Yankwich A. H.
Published: October 2005

It is axiomatic that response to complex waveforms can be predicted for linear systems from pure-tone frequency-response tests in amplitude and phase. However, in speech/hearing aid considerations, direct tests of the characteristic of interest has proved most expedient. That characteristic is, of course, the ability to transduce speech itself. Phonetically balanced word lists were presented to anesthetized guinea pigs and the resulting CM recorded from basal turn differential electrodes. Word lists recorded in this manner were presented to listeners with normal hearing. Quantitative comparisons of the discriminability of such lists, presented both in the quiet and in the presence of background noise sufficient to degrade recognition cues were shown.
Identification of normalized steady-state vowels
Authors: Wakita H.
Published: October 2005

This study was taken up as a first step toward automatic acoustic-phonetic transcription for arbitrary speakers. Sound identification experiments were conducted with nine steady-state American vowels /i, ɪ, ɛ, æ, ʌ, a, u, ᴜ, ɜ/. Reference information for each vowel was determined from vowel utterances in the context “hVd” produced by 16 speakers (nine males and seven females). In this case, the area function for each vowel was computed by use of the linear prediction method and was normalized to a reference length of 17 cm. Based on the resonance frequencies of the area functions thus normalized, the probability density function for the first three resonance frequencies of each vowel category was computed under the assumption of a normal distribution. These distributions were then used for the identification of steady-state vowels produced by an additional ten speakers (five males and five females). The overall rate of correct vowel identification was 83%. A higher recognition rate is expected to result from improving the estimation accuracy of the formant frequencies and bandwidths.
Some preliminary experiments in the recognition of connected digits
Authors: Rabiner L. R. , Sambur M. R.
Published: October 2005

A system is described for recognizing connected digits. The system is essentially speaker independent and has been programmed to recognize strings of three consecutive digits. In order to segment the input utterance into the single digits, a voiced-unvoiced-silence analysis is made using a pattern recognition algorithm. Based on both the voiced-unvoiced-silence contour, and variations in the energy contour of the utterance, a preliminary segmentation of the digit string is made. Boundary adjustments are then made based on a preliminary recognition of the individual digits. Finally a recognition algorithm, similar to the one used in the isolated digit recognition work described by Sambur and Rabiner, is used to classify the individual digits in the utterance. Experiments with the system using ten speakers (five male, five female) in a fairly low noise environment yielded a 91% correct digit recognition score. Similar experiments using ten new speakers (five male, five female) in a noisy computer room yielded an 87% correct digit recognition score.
Linear predictive residual analysis compared to bandpass filtering for automatic speech recognition
Authors: White G. M.
Published: October 2005

It has been recently proposed by Itakura [F. Itakura, “Minimum Predictive Residual Principal Applied to Speech Recognition,” IEEE Symp. Speech Recog. CMU (1974)] that the linear predictive residual can be used as a measure of speech waveform similarity. To measure the similarity between two waveforms, Itakura proposed to construct a linear predictive filter for one waveform and measure the residual (predictive error) for the other waveform. Itakura used this technique to achieve some remarkably good speech recognition scores. We constructed a speech recognition system using both bandpass filtering and linear prediction in order to compare the two techniques. The classifier used dynamic programming. A 36-word vocabulary was used consisting of the alphabet plus digits spoken five times by the same speaker. A single word list was used for training and the other four were used for testing. Speech input was through a noise cancelling microphone. For the digital linear predictive, inverse filtering, analysis, speech was low pass filtered at about 5 kHz and digitized at 10 kHz. For the bandpass filtering experiment, 21 filter channels each 1/3 octave wide wore used covering the audio spectrum from about 100 Hz to 10 kHz. The recognition scores in both cases were 98% correct showing that the linear predictive residual technique is essentially equivalent to bandpass filtering as a means of measuring speech waveform similarity.
Partial word boundary detection from stress contours
Authors: Sargent D. C.
Published: October 2005

A machine algorithm was developed for partial word boundary detection in continuous speech. Word boundary detection was achieved by comparing a computer-extracted stress contour for the 700 syllable test passage with that contour which would have been predicted from rigid adherence to the Alternating Stress Rule. Since this rule functioned only at the word level and below, it was more likely to be violated when crossing word boundaries within a word. The position of any Alternating Stress Rule violation in the extracted stress contour was therefore marked as a probable word boundary location. Utilizing this concept, 44% of the word boundaries in the test passages were correctly positioned with a false alarm rate of less than 10%. Most of the false alarms were caused by the presence of adjacent reduced syllables within the same word. Research is presently being conducted to incorporate additional regularities in the stress patterns of English to further improve the algorithm's performance.
Algorithm to detect the beginning and end points of a speech utterance
Authors: Ganesan K. , Lin W. C.
Published: October 2005

There is a great need to detect the beginning and end points of a speech utterance in applications like speech recognition and speaker identification. In this paper, we present a method for beginning and end-point detection which makes use of the maximum likelihood principle. The features that are used by the algorithm are (1) total per-unit energy, (2) zero-crossing rate, and (3) absolute amplitude of the speech samples, Conditional probability densities are estimated for these three features using a database of 60 phonetically balanced words and ten phonetically balanced sentences spoken by four male speakers with General American accents. A set of optimum thresholds are obtained for each feature such that the probability of classification error is minimized. The algorithm was tested for both isolated words and sentences over a population of six speakers and an error rate of nearly 0% was observed.
Perceptual (aural) and spectrographic investigation of speaker homogeneity
Authors: Rothman H. B.
Published: October 2005

In order to investigate the perceptual and spectrographic homogeneity of speakers, 28 (14 pairs) talkers recorded an extended prose passage on two occasions, one week apart. Twelve talkers were chosen as six pairs on the basis of their having been confused with each other due to the similarity of their voices. A tape was prepared for the presentation of two randomized 2-sec speech segments for each pair of talkers. Listeners made aural/perceptual judgments of same or different for the following conditions: (1) same/contemporary (i.e., one talker recorded at the same time); (2) same/noncontemporary (i.e., one talker recorded one week apart); (3) different (i.e., paired talkers). Preliminary analysis of the data indicate the following: (1) 96% correct identifications were obtained for the same talker paired with a contemporary speech segment; (2) 44% correct identifications were obtained when comparing the same talker with a noncontemporary speech sample; (3) 87% correct identifications were obtained when comparing different talkers of a pair; (4) confusions between contemporary and noncontemporary samples of talker pairs occurred at a 38% level. High identification scores were expected for categories 1 and 3. It is evident that correct identification of a talker drops sharply when the comparison speech sample is noncontemporary. Further research duplicated the above procedure utilizing the same speech samples filtered to match a telephone passband; results were similar to the above. Spectrographic matching will be done for both procedures and results from each will be correlated.