bluuebunny/crossref_metadata_2025 huggingface dataset:
Traffic noise and the open window
Authors: Lawrence Anita B. , Burgess Marion A.
Published: October 2005

Natural ventilation is often the only means of providing fresh air in domestic buildings and it may become the preferred method for other buildings as well, in order to conserve energy. The simplest way of achieving natural ventilation is to open a window or door, but the sound attenuation of the building envelope may be severely reduced. The effect of an opening on facade attenuation may be predicted, if the sound transmission loss values of the facade elements are known. The accuracy of such predictions has been investigated by measuring the traffic noise attenuation of the facades of an experimental building. Various percentages of open window area were examined, and the effect of staggering the opening sashes in a spaced double window was measured. [Work supported by A.R.G.C. and S.P.C.C.]
The search for a biological survival value of music
Authors: Roederer Juan G.
Published: October 2005

A most basic issue in the study of music perception is the question of why humans are motivated to pay attention to, or create, musical messages, and why they respond emotionally to them, when such messages seem to convey no real-time relevant biological information as do speech, animal utterances, and environmental sounds. Expanding on previous work [J. G. Roederer, Physics and Psychophysics of Music (Springer, New York, 1979), 2nd ed.], four possible concurrent factors will be examined: (1) the inborn motivation to train language-handling networks of the brain in the processing of simple, organized sound patterns as a prelude to the acquisition of language; (2) the specialization of the cerebral hemispheres in information processing, in which short-term sequencing as required in speech communication and thinking is separated from holistic pattern recognition as required in music; (3) the fact that in humans limbic system functions can be activated by internally evoked images in complete detachment from the current state of environment and organism; (4) the value of music and rhythm as a means to congregate, behaviorally equalize, and even control masses of people.
Learning a “tonal” vocabulary
Authors: Leek M. R. , Watson C. S.
Published: October 2005

At the last meeting of this Society, we described the time course of learning to detect individual tonal components of a sequential pattern [Leek et al., J. Acoust. Soc. Am. Suppl. 1 71, S37 (1982)]. In this study, the investigation of auditory perceptual learning was extended to an identification task. Seven listeners were first trained to identify four 3-tone mini-patterns or “syllables,” using numbered response keys. All possible combinations of these syllables (without repetition) provided twenty-four 4-syllable “words,” which the listeners were subsequently asked to identify by naming the order of the syllables. After several weeks of daily practice, most listeners learned to correctly identify the words at 80% correct or better. Although rates of learning varied among listeners, the learning curves displayed similar characteristics. As identification became more accurate, response latencies dropped by 60%–70%, supporting subjective reports of an increasingly automatic and unitary perception of the words. An analysis of perceptual confusions and how they were resolved over time shows that some words were learned as whole units. However, many apparently were learned as concatenations of 1-, 2-, or 3-syllable units, perhaps reflecting the creation of a primitive phonological system by the listener. [Work supported by NIH.]
Measurements of equal loudness and reaction times
Authors: Buus Søren , Greenbaum Hilda , Scharf Bertram
Published: October 2005

Kohfeld et al. [Percept. Psychophys. 29, 535–549 (1981)] suggested that reaction times may not be the same for equally loud stimuli. However, their equal-loudness contours showed unusually large level differences between the 1000-Hz standard and the 500- and 5000-Hz comparisons. To investigate the effect of the loudness-matching procedure used by Kohfeld et al., four listeners made equal-loudness judgments using three different methods: (1) a method of limits with the standard and comparison alternating between ears, similar to Kohfeld et al.'s procedure, (2) a method using three interweaved adaptive procedures with a 2I, 2AFC paradigm and monotic, random-order presentation of standard and comparison, and (3) the method of adjustment with monotic, alternating presentation of standard and comparison. Results from the first method resembled those of Kohfeld et al.: at 20, 40, and 60 phons, the 500- and 5000-Hz comparisons were set about 8 dB above the 1000-Hz standard. Results from the second and third methods agreed with each other, but were different from those obtained with the first method: at all three loudness levels, the comparisons were set only a few dB above the standard. Preliminary measurements indicate that reaction times to equally loud tones, as determined with the second and third methods, were approximately equal. [Work supported by NIH grant RR07143.]
Loudness functions of short-duration tone glides from nonmetric scaling
Authors: Pilgreen Kenneth L. , Cullen John K.
Published: October 2005

Individual loudness functions of short-duration (20 ms) tone glides and pure tones were obtained for three listeners. Upsweep and downsweep tone glides varied linarly between endpoint frequencies of 500 and 2500 Hz; binary judgments were made by subjects at ten intensities between 30 and 90 dB SPL. Subjects judged loudness differences between tone pairs, and loudness projections were derived using a multidimensional unfolding program developed by Schneider [J. Acoust. Soc. Am. 69, 1208–1209 (1981)]. Loudness differences between the tone glides and pure tones occurred over most of the range of intensities; some differences occurred between upsweep and downsweep tone glides at the highest levels tested. These results indicate that for short-duration signals with rapid changes in frequency, loudness growth is a steeper function that for pure tones of similar duration.
Seismic survey signals in the Canadian Beaufort Sea
Authors: Greene Charles R.
Published: October 2005

In conjunction with a study of the responses of bowhead whales to noises from petroleum industry activities in the Beaufort Sea, we recorded signals received from sleeve exploders at a number of ranges from 8 to 29 km We investigated the detailed nature of these signals, including their spectral content and waveforms, and used the results to describe sound transmission loss in the shallow (<50 m) waters of the southeastern Beaufort Sea. The major part of the received signal began at about 200 Hz and swept down to about 100 Hz. The duration ranged from 250 ms at 8 km to over 400 ms at 29 km, with reverberation extending much longer. We derived a regression model (R2 = 0.972, 12 measurements) with cylindrical spreading plus an absorption loss term of 1.39 dB/km for signal components around 150 Hz. [Work supported by the U.S. Bureau of Land Management.]
The application to real data of a technique for measuring the plane-wave reflection coefficient of the ocean bottom
Authors: Frisk George V. , Mook Douglas R. , Doutt James A. , Hays Earl E. , Oppenheim Alan V.
Published: October 2005

A technique has been described for the measurement of the plane-wave reflection coefficient of a horizontally stratified ocean bottom [G. V. Frisk, A. V. Oppenheim, and D. R. Martinez, J. Acoust. Soc. Am. 68, 602–612 (1980)]. It is based on the exact Hankel transform relationship between the reflection coefficient and the bottom reflected field due to a point source, and was shown to yield excellent results with synthetically generated data for simple bottom examples. We apply the method to real 220-Hz data obtained using a near-bottom experimental geometry. The results of the Hankel transform inversion are compared with those obtained using an iteration of forward models technique. [Work supported by ONR, Johns Hopkins Applied Physics Laboratory, and NORDA.]
Propagation through refracting ocean sediments
Authors: Besieris Ioannis M. , Kohler Werner , Freese Herbert
Published: October 2005

A transport theoretic analysis of propagation through highly anisotropic randomly perturbed sediment layers has previously been developed for the case of constant mean density and sound speed. [J. Acoust. Soc. Am. 12, 937–946 (1982); preliminary results reported in J. Acoust. Soc. Am. Suppl. 1 70, S1 (1981)]. The present paper extends this work to include the effects of refraction. The effect of variations in the mean density and sound speed upon the mean field and incoherent intensity is discussed. [Work Supported by ONR Contract No. N00014-76-C-0056 and NAUSEA Code 63D.]
General Rayleigh angle phenomenon
Authors: Adler Laszlo , de Billy Michel , Norris Andy
Published: October 2005

Experimental and theoretical work is presented to investigate the interaction of finite ultrasonic beams with liquid-solid interfaces. The results indicate that for any angle of incidence leaky waves are generated. These leaky waves are radiated to the liquid from the solid suface at the Rayleigh angle. For a general angle of incidence the amplitude of these leaky waves are much smaller than the amplitude of the specularly reflected wave. A special case of this general phenomenon is the Rayleigh angle incidence which produces the null strip in the forward direction and low amplitude scattering in the backward direction.
Nonspecular reflection and transmission of ultrasonic bounded beams having an nth-polynomial intensity distribution
Authors: Ngoc Tran D. K. , Mayer Walter G.
Published: October 2005

Theoretical investigations of the nonspecular reflection or transmission effects in the past have been done mainly for an incident beam assumed to have a Gaussian intensity distribution. This may not be satisfactory in many cases where a beam is characterized by a non-Gaussian profile. This paper describes nonspecular effects for an incident beam whose intensity distribution is modeled by a general nth polynomial, providing more flexibility in simulating reflection and transmission phenomena for bounded beams. An extension of the spectral representation of bounded beams leads to calculations of reflected beam profiles at critical angles associated with a solid-liquid interface for an nth polynomial incident beam. Sample nonspecular reflection and transmission profiles are calculated for a more complex layered media system, i.e., a solid plate immersed in a liquid. Results are compared with known nonspecular characteristics associated with Gaussian incident beams. [Work supported by Office of Naval Research, U.S. Navy.]
Borehole acoustic reflection coefficients at a horizontal interface
Authors: Chang S. K.
Published: October 2005

This paper describes results of borehole acoustic reflection coefficients at a horizontal interface obtained from the finite element method (FEM). A fluid filled borehole perpendicular to the plane interface between two adjacent solid formations is considered. The reflection coefficients of compressional and shear head waves and the Stoneley mode at the boundary are obtained quantitatively. From the study of varying formation parameters and frequencies, we have observed that the compressional and shear head wave reflection coefficients are the same as those of compressional and shear plane waves normally incident on a plane boundary, as if the borehole were not present. The reflection coefficient of the Stoneley mode is dispersive and has a phase shift. The asymptotic Stoneley wave reflection coefficient can be derived by assuming no mode conversions. It was found that the asymptotic Stoneley reflection coefficient is off by a factor which is caused by mode conversions at the edge. We thus define a “mode conversion factor” to be the ratio of FEM to asymptotic results. The mode conversion factor is monotonically decreasing as frequency increases. It is approaching unity at low frequencies, indicating the dominance of Stoneley wave and the validity of the asymptotic reflection coefficient.
Influence of chemical composition on dynamic properties of neoprenes for transducer applications
Authors: Capps Rodger N. , Thompso Corley M.
Published: October 2005

Elastomeric materials are widely used in the construction of wet-end sonar equipment. The viscoelastic nature of these materials causes them to possess and exhibit some extraordinary properties. Unless these properties are properly utilized, it can be disastrous to the performance of a transducer. Neoprenes are often used as components in transducers, due to the superior chemical and physical response properties of neoprene to many environments. However, the dynamic properties of neoprenes may often be inferior to those of other types of elastomers. Since these properties are important for transducer applications, they should be optimized, with additives being used to provide desirable chemical and physical properties. In this paper, the effects of carbon black type and loading and variation of base polymer on a series of neoprenes have been investigated. The dynamic moduli and loss tangents have been characterized for a number of these elastomers. Based on the experimental results, the suitability of these materials for transducer applications and the optimization of dynamic properties of transducer elastomers will be discussed. [Work supported by NAVSEA 63R.]
Some considerations on resistivity and permeability in the design of a reliable transducer elastomer
Authors: Thompson Corley M.
Published: October 2005

Neoprene elastomers are widely used as acoustic transducers but have rarely been optimized for their application. Electrical resistivity and water permeability are important properties in the design of a transducer elastomer. However, their dependency on the elastomer composite is generally unknown. A study was therefore designed to investigate the effects of different types and proportions of fillers on these pertinent physical properties. Three common neoprene types, each with a standard lead oxide cure system, were used. The dependency of resistivity on carbon black loading is found to be described by a sigmoidal curve for each carbon-black type. Ramifications of the frequently specified properties such as shore hardness and tensile strength on the resistivity will be discussed. Changes in electrical resistivity with seawater exposure will also be described. The dependency of the water permeability of the neoprene on some of the composition parameters has been determined. The effects of both of these variables on transducer lifetime and reliability will be discussed. [Work supported by NAVSEA 63X.]
Elastomers in Mulloka sonar staves
Authors: Oldfield D.
Published: October 2005

This paper will present a case study of the use of elastomers in the underwater transducer array of the Australian designed Mulloka sonar system. The successful long-term operation of the sonar depends upon correct choice of materials to keep the interior of the array staves dry. A combination of factors led to severe corrosion inside the prototype staves which were subsequently refurbished with a butyl rubber coating over a cast polyurethane rubber membrane. Later laboratory studies showed that the sprayed butyl rubber coating was much more permeable to water vapour than a brushed coating. The rate of increase of relative humidity inside the array whilst in service with the Royal Australian Navy correlated well with the rate predicted from laboratory measurements. Experience with the prototype array clearly indicated the need for a much less permeable system for the production version. The design eventually adopted consisted of a pre-vulcanized bromobutyl rubber membrane bonded to the transducer heads and to the stave housing. The stave was then encapsulated in polyurethane to maintain the integrity of the rubber/metal bonds. A limited amount of accelerated testing of actual staves gave moisture permeation results in good agreement with laboratory data. These results lend further support to the view that moisture ingress should not be a problem during the service lifetime of the transducer array.
Fabrication of nonorthotropic axially stiffened polyurethane mandrels for use in fiber optic hydrophones
Authors: Africk S. , Jameson P. , Ordubadi A.
Published: October 2005

Ideally, extended hydrophones consisting of optical fibers wound on a compliant cylinder have high radial compliance to maximize sensitivity per unit length and high axial stiffness to minimize effects of longitudinal dynamics to assure uniform frequency response. Bendability is also desirable in certain applications. A set of nonorthotropic mandrels consisting of polyurethane cylinders with embedded axial steel wires have been fabricated. These include two levels of stiffening and polyurethanes of four degrees of hardness. Several aspects of the molding technique used, including process selection, mold design, air bubble requirements, and adhesion of the elements are described.
Rules for the performance of melodies. Origin, functions, purposes
Authors: Frydén Lars , Sundberg Johan
Published: October 2005

In J. Acoust. Soc. Am. Suppl. I 69, S103 (1981) a computer program was presented, which works as a musical version of a text-to-speech-conversion program. Thus, the input is the melody in musical notation, and the output is the melody played. The “pronunciation rules” in this program, which serve the purpose of improving the musical quality of the performance, have now been further developed. New rules have been formulated which work with a time window corresponding to one or several bars. In a formal test the musical effect of these rules have been approved by a group of professional musicians. The purpose and means of the rules are discussed. Some rules apparently serve the purpose of emphasizing unexpected notes or marking structural components of the melody such as chord shifts and phrases. The ways in which this is signaled in the performance often show a striking similarity with rules for speech suggesting that the rules refer to the listener's acquaintance with speech. Other rules seem to allude to the listener's previous experience of motion. In this way, the project seems to shed some light on some basic requirements for music communication.
Synthesis of consonants in singing
Authors: Zera Jan , Sundberg Johan
Published: October 2005

In previous singing research hi-fi synthesis efforts have mainly aimed at long, sustained vowel sounds. The present paper reports on an attempt towards hi-fi synthesis of some consonants in singing. The synthesis is made by means of a formant synthesizer (MUSSE) complemented by two pole zero circuits, two noise generators, and a filter. Examples of the synthesis will be played.
Chasing the lost chord with an Apple computer
Authors: Gibian Gary L. , Harnden Eric
Published: October 2005

The twentieth century has seen the rapid growth of electronic synthesis and reproduction of music, to the point where “a major part of recent popular and commercial music would not exist without synthesizers and…the recording studio…has itself become a musical instrument…” [Gordon Mumma, in Electronic Music (Allen Strange, 1983)]. The Audio Technology Program at The American University includes a course in Digital Music Synthesis based in part on the Soundchaser system manufactured by Passport Designs for the Apple computer equipped with Mountain digital circuit cards. Measurements of performance parameters (e.g., the discrete nature of the attack, decay, and release) will be discussed and musical excerpts will be presented.
A procedure for calibrating ear canals at high frequencies
Authors: Green D. M. , Stevens K. N. , Berkovitz R. , Derr A. , Krasner M. , Pyle R.
Published: October 2005

A system for delivering a sinusoidal signal of known sound pressure to the ear at high frequencies (8–20 kHz) is explored. A high-frequency driver unit is coupled to the ear canal through a long tube, so that the acoustic source at the ear-canal entrance had an impedance close to ρc. The system is calibrated by applying an impulse of voltage to the source and measuring the response at a small microphone located in the coupling tube close to the ear-canal entrance. A signal-processing procedure detects the zeros in the spectrum of this response and uses these data to estimate the transfer function from the source voltage to the sound pressure at the inner end of the ear canal. The system has been calibrated for a number of different ears in this way, and data giving the range of characteristics of the ear canals as determined by the zero locations will be described. In general, the results are consistent with theoretical predictions based on the known average shape of the ear canal. [Supported by a contract from NINCDS.]
Determination of eardrum reflectance using measurement of phase
Authors: Stinson Michael R.
Published: October 2005

At frequencies greater than 8 kHz the acoustic energy reflectance at the eardrum is not well established in living human subjects. This quantity is of interest, though, in high-frequency audiometry and in network modeling of the middle ear. In this paper a technique for measuring high-frequency reflectances is discussed that makes use of the phase component of a pressure signal, rather than its amplitude. In a section of ear canal having a constant cross section, or having a constant taper, the maximum rate change of phase with position is simply related to the energy reflectance at the eardrum. Experimentally the phase of the pressure signal is determined at several positions over a 2-mm distance, centered about an interference minimum. By choosing appropriate sound frequencies the measurements can be confined to a 6- or 7-mm region near the ear canal entrance; this avoids the deep penetration of probe microphones required by other techniques, and avoids the large variations in ear canal cross section that occur close to the eardrum. Preliminary results have been obtained, suggesting an eardrum energy reflectance of about 80% (25-dB equivalent standing wave ratio) at 15 kHz.
Digital measurement of acoustic reflex response in normally hearing subjects
Authors: Robinette L. N. , Thompson D. J. , Nalty D. F.
Published: October 2005

Determination of acoustic reflex response morphology requires an aural acoustic immittance instrument capable of accurate measurement of complex immitance. Unfortunately, conventional analog instruments are either (1) incapable of measuring complex immittance or (2) do so inefficiently and with long time constants. Accurate data can be obtained, however, with a digital immittance instrument. Acoustic reflex response measurements were obtained using a digital acoustic immittance instrument (226-Hz probe tone) and a laboratory computer. Activating signals (1-s duration) were four tones and broadband noise presented in 5 dB increments (maximum 120 dB SPL) from − 5 to + 30 dB re: acoustic reflex threshold (ART). Ten subjects were tested per decade of age from 20 years through 79 years. Results for the 2-kHz tone and BBN at 20 dB re: ART indicated that (a) slope of onset increased with signal level, (b) response slope during signal presentation was greater for noise than for the 2-kHz signal, (c) baseline, attack time, onset latency, and amplitude of maximum response decreased for the oldest age group, and (d) release time and recovery time increased for the oldest age group. [Work supported by Rehabilitative Research and Development Service of Veterans Administration.]
A model of cochlear processing
Authors: Shamma Shihab , Chadwick Richard S. , Wilbur John , Rinzel John
Published: October 2005

A mathematical model is developed to describe the transformation from acoustic stimulus to intracellular hair cell potentials in the mammalian cochlea. The model incorporates a physiologically reasonable linear formulation of basilar membrane mechanics, a treatment of basilar membrane-cilia displacement coupling, and a simplified description of the inner hair cell nonlinear transduction process based on recently published data of intracellular recordings. The model at this stage is restricted to frequencies below 2000 Hz. The computed responses to single tone inputs display the major qualitative features of hair cell intracellular potentials and auditory nerve fiber activity (e.g., frequency tuning; rectified waveforms; saturating rate-level functions). The computed results also account for some subtle effects of stimulus intensity on frequency tuning of phase locked responses observed experimentally in both inner hair cells and auditory nerve fibers. For example, experiments reveal that (1) the bandwidth of the frequency selectivity increases with intensity, and that there are (2) downward (upward) shifts of the best frequency of units tuned above (below) approximately 1 kHz with increasing intensities. In the model, the computed ac outputs show both these trends. The first is primarily due to the saturating effect of the hair cell nonlinearity. The second results as a consequence of both the nonlinearity and the combined effect of the high-pass transfer function of basilar membrane-cilia coupling and the inner hair cell low-pass transfer function. In contrast to these shifts along the frequency axis, the model does not exhibit intensity dependent shifts of the spatial location along the cochlea of the peak response for a given single tone. The observed shifts, therefore, may not be disruptive to a stable tonotopic code.
Adaptation and variability of spike discharge of auditory nerve
Authors: Westerman Larry A. , Smith Robert L.
Published: October 2005

The response of afferent fibers in gerbil auditory nerve to constant intensity tone bursts was observed. The rapidly declining rate during the first 10 ms appears to have lower variability than the response during the steady state. That is, PST histograms appear smoother during the rapid adaptation phase than at later times. We tested this impression by calculating pulse-number distributions. Histograms of bin width T were constructed by dividing the response record of single fibers into N subsets. The mean and variance of the number of spikes in each bin of the subset PST histograms were calculated, for various values of N and T. We observed that the variance-to-mean ratio was relatively constant and independent of (declining) firing rate during the adapting response, except for the onset 1-ms bin. At high intensities the probability of firing approached unity during the onset 1-ms window, so that the variance approached zero. At all later times, the ratio was near unity, consistent with a Poisson process with a relative refractory period.
Two-tone interactions in the auditory cortex of the squirrel monkey
Authors: Shamma Shihab , Symmes David
Published: October 2005

Two-tone interactions are recorded in the responses of single units in the superior temporal gyrus to contralateral acoustic stimulation of the awake squirrel monkey. Four response types are distinguished based primarily on the nature of the two-tone response, and secondarily on criteria such as the patterns of response to single tones and noise stimuli, thresholds, and spontaneous activity levels. Type A units (24/80) display strong lateral inhibitory influences which may extend up to two octaves on either side, or both sides, of the BF. They are sharply tuned at all intensities, and generally exhibit sustained response to single-tone stimuli at the BF. The units have nonmonotonic rate-level functions, and where tested, show little or no response to broadband noise. Most type A units have low spontaneous rates (< 1 spikes/s), and relatively high thresholds (>30 dB SPL). Type B units (22/80) are characterized by relatively high spontaneous rates of activity (>20 spikes/s) and inhibitory responses to single-tone stimuli. Broadband noise is applied to a few type B units, and in all cases it evokes strong excitatory response. Type C units (17/80) summate the responses to the two-tone stimulus, and show little or no inhibitory influences. They have V-shaped tuning curves, monotonic rate-level functions, low thresholds (<30 dB SPL), moderate spontaneous rates (∼ 10 spikes/s), and a strong and sustained response to noise and single tone stimuli. Type D units (17/80) show “temporal inhibition” to two-tone stimuli, in that an excitatory response to the first tone suppresses (adapts or inhibits) the response to the second tone. These units generally have moderate to broad frequency tuning and phasic responses to single tone stimuli. Histological examination of electrode tracks suggests that type A units are restricted to A1 (and possibly the rostral field) while other types are distributed over all auditory fields.
PET imaging during auditory stimulation
Authors: Sidtis John J. , Jarden Jens O. , Kearfott Kimberlee J. , Rottenberg David A.
Published: October 2005

Positron emission tomography (PET) provides a means of studying regional brain activity in vivo. PET measurements of regional cerebral blood flow (rCBF) were obtained in 3 subjects with normal hearing during the continuous inhalation of CO15O. A nominally unstimulated 3-min period, during which a moderate level of apparatus noise was present, was followed by the continuous binaural presentation of white noise (3 min). In addition, dichotic stop-consonant and complex pitch discrimination tests (3 min) were administered to two subjects. White noise produced 10%–15% and 15%–25% increases in rCBF in the temporal lobes and thalamus, respectively. Increases were also observed in nonauditory structures: 10%–25% in medial frontal cortex and 5%–10% in medial occipital cortex. In contrast, maximum changes in rCBF during speech and pitch discrimination were of smaller magnitude and occurred over more restricted cortical regions. These results suggest that continuous white noise produces significant increases in rCBF in both auditory and nonauditory areas. The relative magnitude of this effect compared to rCBF changes observed during auditory pattern discrimination suggests that regional brain activity associated with specific auditory functions is likely to be extremely focal and that the quantitation of such activity requires well-controlled within-subject studies. [Supported by NIH.]
Ceramic-polymer composite transducers
Authors: Newnham R. E.
Published: October 2005

One of our major interests in the past few years has been in the development of diphasic transducer materials made from polymers and lead zirconate titanate (PZT) ceramics with high hydrostatic pressure sensitivity. The concept of phase connectivity, the manner in which the individual phases are interconnected, has been used to optimize the electric flux pattern and mechanical stress distributions in attaining remarkable improvements in the hydrostatic strain coefficient (dh) and the hydrostatic voltage coefficient (gh) over the corresponding values of solid PZT ceramics. Recent results on 0-3, 1-3, 1-3-2, 2-2, 3-1, 3-2, and 3-3 composites will be presented, and a comparison made with polyvinylidene fluoride and other hydrophone materials. When driven at high frequency the composite transducers exhibit a number of interesting modes of motions in which the component materials sometimes vibrate out of phase. Some of the proposed applications for composite transducers will be described.
Optimization of the transmitting characteristics of a tonpilz-type transducer by proper choice of impedance matching layers
Authors: VanCrombrugge Michel , Thompson William
Published: October 2005

Many attempts have been made to design wideband transducers. These attempts were concentrated on simple configurations such as a single piezoceramic disk with a limited number of impedance matching layers on its front and/or back faces. For the complex-structured tonpilz transducer, the methods described in the literature are no longer appropriate. Furthermore, trial-and-error attempts to choose matching layers to obtain better performance are time consuming. Consequently, a systematic procedure based on the Mason equivalent circuit representation of the transducer and the nonlinear goal programming algorithm has been implemented. This procedure allows one to design both broadband and high-power transducers. The mathematical implementation of this procedure produces excellent results. Moreover, it can easily be adapted for other design objectives such as minimization of weight, cost, size, etc. [Work sponsored by the Naval Sea Systems Command.]
Preliminary design rationale for tonpilz transducer elements
Authors: Thompson Stephen C. , Hess Stephen
Published: October 2005

Analysis methods for the prediction of performance parameters for tonpilz transducer elements are quite common. Given a physical design, the methods of equivalent circuit analysis, one-dimensional plane-wave modeling, or finite element modeling each gives useful approximations of increasing accuracy. However, none of these methods can provide a design from a given set of performance requirements. They are analysis methods rather than design methods. This paper presents a rationale for the development of a preliminary design method for tonpilz transducer elements. The algorithm requires input values for the transducer resonant frequency, 3-dB bandwidth, radiated power level, and beamwidth. The output is a simple tonpilz element consisting of a head mass, a tail mass, a ceramic stack with minimum volume, and a stress rod if desired.
A figure of merit for head mass materials for broadband transducer applications
Authors: Gray John J.
Published: October 2005

In the past it has been proposed that the transducer designer use the specific rigidity as a figure of merit (FOM) for transducer head mass materials. This FOM places a premium on high flexural resonance frequency for a given head mass thickness, but it is not useful in selecting materials for broadband applications where a small value of mass is desired. Using the specific rigidity, steel would have a higher FOM than magnesium, despite the fact that for broadband applications magnesium is usually preferable. A new FOM is proposed which simultaneously places a premium on low mass and high-flexural resonance frequency. This FOM is the specific rigidity divided by the density.
Interferometric measurement of the magnitude of acoustic transducer motion
Authors: Fein Howard
Published: October 2005

Experiments have shown that the magnitude of the displacement of excited acoustic transducers can be simply and very accurately measured employing a technique called Speckle Field Interferometry. The application of a specially designed Speckle Field Displacement Interferometer to problems of motion measurement has resulted in the successful quantitative characterization of the behavior of certain transducers. These characterizations are part of a program, which includes holographic interferometry [H. Fein, J. Acoust. Soc. Am. Suppl. 1 73, S24 (1983)], to accurately evaluate the performance of transducer systems and are shown to be of great value in defining actual operating dynamics. Interferometric data, methods, and results are presented.
Ratio of specific heat γ of humid air
Authors: Wong G. S. K. , Embleton T. F. W.
Published: October 2005

For primary microphone calibration (and in some thermodynamic applications) it is necessary to have a precise knowledge of γ. In national and international microphone calibration standards, a value of 1.402 is recommended for dry air, and there is no information on γ for humid air. Based on known theoretical and experimental thermodynamic data on the constituents and properties of humid air, the values of γ for various degrees of relative humidity h (dimensionless), and ambient temperatures t (degrees Celsius) have been computed for the first time. An empirical equation in terms of h and t has been obtained to fit the precisely calculated values for γ. By ignoring the effects of humidity on γ, the sensitivities of microphones calibrated in ambient air can be underestimated by approximately 0.01 dB, an amount which is greater than the currently attainable uncertainty in reciprocity calibration. A direct acoustical method to verify the variation of γ with humidity is discussed.
Measurement of plate waves
Authors: Rasmussen Gunnar
Published: October 2005

Progressing waves in plates transport energy. The flow of energy will pass from the source of excitation to the damping mechanism. The flow may be measured using two accelerometers with a known spacing. The acoustic intensity flow, very near and parallel to the plate surface, follows closely the wave motion of the place. Theory of mechanical flow measurements in plates, and in the very near acoustic field, will be reported together with presentation of measurement results. The application of vibration intensity measurements is useful in the field of noise reduction as well as structural analysis.
The Singapore construction noise standard
Authors: Heng Raymond B. W.
Published: October 2005

With the construction boom presently being experienced in Singapore and further massive construction and demolition programs expected for the proposed new Mass Rapid Transit system, construction noise is now a major problem that has to be controlled with urgency. Studies for the development of a suitable Singapore Code of Practice for control of noise from construction and demolition sites began in 1978 with investigation of the standards of other countries available at that time. Local construction methods and equipment were surveyed and noise studies carried out at various sites. A survey was conducted among residents in different parts of the country, zoned according to differing local conditions and sensitivities. Laboratory studies were also carried out to determine subjective response of the local population to the noises expected during various stages of the construction works. From these, the Leq equivalent energy level unit was chosen as an adequate noise descriptor but the Leq (5 min) was adopted rather than the more usual daily or 12-h Leq for prediction, measurement as well as control purposes. Considerable thought was given to establishing acceptable noise levels which continue to be economically realistic for the survival of the local construction industry. Some of the aspects involved in the implementation of noise control procedures as well as the extent to which public approval could be more effective than resorting to the usual legal actions are reviewed.
Perception of complex-tone pairs mistuned from unison: Waveform relations determines whether pitch slides or iterated complex auditory patterns are heard
Authors: Warren Richard M. , Brubaker Brad S. , Gardner Daniel A.
Published: October 2005

When a broad-spectrum complex tone (CT) (whether derived from a voice, musical instrument, pulse train, or randomly generated waveform), having a stable frequency and containing harmonics above the 7th or 8th, is mixed with itself after a slight (1 Hz or less) change in the waveform repetition frequency, listeners hear a rising glissando when fine structures of the correlated waveforms approach alignment and a falling glissando as they move away. If harmonics above the 8th are removed, multiple beats are heard (not glissandi) with the dominant repetition frequency equal to the difference (in Hz) between the CTs. When two broad-spectrum uncorrelated CTs mistuned slightly from unison are mixed, complex periodic patterns rather than glissandi are heard: Multiple beats dominate following removal of harmonics above the 8th (the dominant repetition frequency heard in each case equals the difference in Hz between the uncorrelation CTs). These observations provide information concerning the nature of spectral and periodicity analyses of iterated acoustic patterns. [Work supported by NSF.]
Accuracy and perceptual asymmetry during dichotic pitch discrimination
Authors: Sidtis John J.
Published: October 2005

Dichotic listening studies with normal right-handed listeners and with patients who have suffered focal cortical lesions suggest that the right hemisphere plays an important role in complex pitch discrimination. The perceptual asymmetry observed in normal listeners was studied using a dichotic recognition test consisting of 500-ms square wave tones with fundamental frequencies corresponding to the 12 semitones in the octave 261.63–523.25 Hz. A diotic recognition probe followed the presentation of each dichotic pair. The probe was identical to one of the dichotic items on 50% of the trials. On the remaining trials, the probe differed from one of the dichotic items by 0.25, 0.50, 0.75, or 1.00 semitone. Subjects who demonstrated a left ear advantage on this test were significantly more accurate in their pitch discrimination than were subjects who demonstrated a right ear advantage. Within each group, left and right discrimination functions were similar. The right ear advantage for pitch discrimination may reflect a sub-optimal strategy for processing pitch or for selecting dichotic signals. [Supported by NIH.]
The dependence of noise edge pitch and binaural edge pitch on the frequency width of the edge
Authors: Hartmann W. M.
Published: October 2005

A low-pass noise band with a sharp spectral edge produces a sensation of pitch, noise edge pitch (NEP), which matches a sine tone having a frequency below the noise edge frequency. Similarly a high-pass noise band results in a NEP above the edge frequency. Dichotic noise with an interaural phase shift varying rapidly with frequency at an edge frequency produces the binaural edge pitch (BEP). The BEP is bimodal and is normally equal to both the low-pass and the high-pass NEP. We performed pitch matching experiments to study both NEP and BEP as functions of the width of the edge. Edge center frequencies were between 150 and 1500 Hz, and the edge widths were 0%, 10%, 20%, and 40% of the edge center frequencies. Experimental variance increased with increasing edge width, but less than proportionally. The low-pass NEP increased systematically with increasing width, especially for edge frequencies above 300 Hz, where the NEP exceeded the edge center frequency for 30% and 40% widths. The high-pass NEP changed less predictably and it usually remained above the edge center frequency. The two modes of the BEP distribution changed less with increasing edge width than did either NEP. This difference in dependence challenges dichotic pitch perception models in which the BEP and the NEP have a common central origin. [Work partially supported by the NIH Grant 17917.]
Binaural coherence edge pitch
Authors: Hartmann W. M.
Published: October 2005

The binaural coherence edge pitch (BICEP) is a dichotic broadband noise pitch effect similar to the binaural edge pitch. The noise is made by summing sine waves with equal amplitudes and random phases. The interaural phase angle is a constant for sine wave components with frequencies below a chosen frequency, and it is a random variable for components with frequencies above that frequency. The chosen frequency is a coherence edge because the signals to the two ears are mutually coherent within any band of frequencies below the edge and they are mutually incoherent in any band above the edge. Sine tone pitch matching experiments show that the BICEP exists for coherence edge frequencies between 300 and 1000 Hz and that it is always matched by a frequency above the edge frequency, by 5%–10%. The effect can be extended to higher edge frequencies, at least 2000 Hz, if the listener is appropriately cued. The results do not depend upon whether the coherent components are presented in phase or completely out of phase to the two ears. For the opposite case, coherence above the edge frequency and incoherence below, the BICEP can be reliably matched only for coherence edge frequencies between 300 and 600 Hz, and the matching frequency is invariably below the coherence edge frequency, by 10%–20%. [Work supported by the National Institutes of Health Grant 17917.]
From sagittal distance to area. A study of pharyngeal cross-sectional area of computer tomography
Authors: Johansson Carina , Sundberg Johan , Wilbrand Hermann
Published: October 2005

In studies of the articulation in speech, data on the pharynx are scarce. Still the pharynx is an important part of the vocal tract. The present paper reports on an attempt to use computer technology. Tomograms were taken at four levels in the pharynx of a male and a female subject sustaining the vowels /u, i, ɑ, œ/. From the tomograms, the lateral width and the cross-sectional area are measured and their relations to the sagittal distance from the back pharynx wall to the midline of the tongue are examined and compared with previously published data. The results suggest relevant interindividual differences.
Coarticulation in lateral pharyngeal wall movements
Authors: Parush Avraham , Ostry David J.
Published: October 2005

Medial movements of the lateral pharyngeal wall (LPW) at the level of the velopharyngeal port were examined using a computerized ultrasound system. Subjects produced CVNVC sequences with all combinations of the vowels /a/ and /u/, and the nasal consonants /n/ and /m/. The flanking consonants were always /p/. The effects of either vowel upon the CVN or NVC gestures (opening or closing of the velopharyngeal port, respectively) were assessed in terms of displacement, duration, and movement onset time. Both CVN and NVC gestures were primarily affected by the initial vowel: movements had less displacement when the initial vowel was /a/. The onset of the CVN (opening) gesture was affected by the final vowel: the movement started earlier, during initial consonant closure, when the final vowel was /a/. In addition, the duration of this gesture was longer when the final vowel was /a/. Finally, no consistent carryover effects of the initial vowel were found upon the onset time or duration of the NVC gesture. The findings are discussed in terms of the role of LPW movements in the operation of velopharyngeal port.
Velar position and port size: Spectral and perceptual effects
Authors: Bell-Berti F. , Baer T. , Raphael L. J.
Published: October 2005

We have used an articulatory synthesizer to study the effects of independent and systematic changes in velar position and velar port size on vocal tract transfer functions of vowels. We have also examined the acoustic and perceptual effects of combining these components of natural nasalizing gestures. Lowering the velum, in the absence of nasal coupling, has small effects, primarily on F2 and F3 frequencies. On the other hand, opening the port without lowering the velum has the greatest influence on F1 frequency, shifting it upward or downward, as necessary, to produce a concentration of spectral energy at about 400 Hz. As expected, the combined effects of lowering the velum and opening the velar port are more heavily influenced by nasal coupling than by changes in velar position. We have also found differences in the degree of perceived nasality associated with velar port areas from 0 to 84 mm2, as a function of the oral vowel (0 mm2) quality. [Work supported by NINCDS.]
The effect of a cyclonic ring on 3-D ray geometry
Authors: Pitre R. , Foreman T. L.
Published: October 2005

A 3-D ray trace model has been constructed and employed in an examination of horizontal deflection effects due to a cyclonic ring. The ring examined had a radius of 125 km, a maximum flow rate of 100 cm/s, and a maximum isotherm uplift of 300 m. Effects of fluid motion on ray geometry were found to be negligible; but horizontal gradients of the index of refraction caused significant deflection. The maximum deflection of 0.75° occurred for a ray traveling along the SOFAR channel axis. Rays which oscillate about the SOFAR axis experience less horizontal deflection. An examination of deflection versus impact parameter indicates that the rays which encounter the eddy with an impact parameter of roughly one-half of the eddy radius experience maximum deflection. A group of rays launched in the same vertical plane experiences an azimuthal angle dispersion of 0.5° in crossing the eddy. [Work supported by the Office of Naval Research.]