bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the vocal effort on vowels
Authors: Benedetto Maria-Gabriella Di , Liénard Jean-Sylvain
Published: October 2005

Vocal effort is one of the less studied sources of speech variability. An investigation of its effects on French vowels was carried out. Twelve French vowels uttered in isolation by 13 speakers, 7 females and 6 males, were recorded. The subject was instructed to repeat the vowel pronounced by the operator with three degrees of vocal effort induced by the distance between the speaker and the operator (30 cm and 1.5 and 7 m); the variations kept within the interval encountered in the usual living conditions, far from the whispered or shouted types of voice. Some of the speakers were recorded twice, 6 months apart. The resulting 720 tokens were assessed by a separate group of listeners who judged vowel identity, perceived speaker’s gender, and perceived vocal effort. Results of acoustic analysis show a change in the global slope of the spectrum and a significant increase of the F1 frequency correlated with the degree of vocal effort, with some dependency on the particular vowel and speaker. The average increase is about 50 Hz between the two extreme speaking conditions, corresponding to an interval of about 12 dB in the overall level. [Work supported by a CNRS-CNR cooperation.]
Trans-syllabic spread of consonantal effects on vowel formant frequencies
Authors: Hawkins Sarah , Slater Andrew
Published: October 2005

Formant-based synthetic speech is less robust in noise than natural speech and is often criticized as ‘‘robot-like.’’ One reason may be the failure to model nonlocal spectral variation induced by segments in other syllables. This study investigates how a single consonant can affect vowel formant frequencies in nonadjacent as well as adjacent syllables. Sequences of /schwa u i schwa/ with intervening consonants were embedded in carrier phrases to give quasimeaningful sentences. The medial consonant was /z/ or /r/. Flanking consonants were either all /b/, or /d/ in the syllables before and after the medial consonant (/bschwabu{zr}ibschwab/, /bschwadu{zr}idschwab/). Primary stress was on either the second syllable, or the first and third. Steady-state or mid-point frequencies of F1–F3 were measured from LPC spectra. Preliminary results confirm expectations: /r/ engenders lower formant frequencies than /z/ in less-stressed, all-b contexts, even in nonadjacent syllables. Vowel stress and /d/ contexts tend to block the spread of differences due to /z/ or /r/, presumably because the tongue is more constrained. Many of these differences are audible; their contribution to robustness and naturalness of synthetic speech will be described. [Work partly supported by Telia Promotor Infovox AB.]
Phonetic variants of Taiwanese ‘‘voiced’’ stops
Authors: Pan Ho-hsien
Published: October 2005

Taiwanese (Amoy) is one of only a handful of Chinese languages that have a third ‘‘voiced’’ stop type contrasting with aspirated and unaspirated voiceless stops at same place of articulation. As in other languages with ‘‘voiced’’ stops, the phonetic realization of Taiwanese /b/ and /g/ is highly variable from one context to another. For example, in utterance initial position, they are said to be ‘‘prenasalized’’ as well as prevoiced and Zhang [1981, Tai Wan Min Nan Fang Yen Gi Yau] even claims that they are replaced by homorganic nasals [m] and [■] when the syllable is closed by a nasal. The positional variants were examined using oral and nasal airflow recordings from seven male native speakers. Three types of syllable structures were chosen with initial voiced stops in CV, CVN, and CVC. The target syllables are placed in utterance initial position and in medical positions after nasals, vowels, and voiceless stops. Initially, there is clear voicing during the closure, while the presence of prenasalization is speaker dependent. When the target syllables are medially, the voiced stops become nasals when preceded by nasals, and otherwise are plain voiced stops with no prenasalization.
Attributes of lateral consonants
Authors: Stevens Kenneth N. , Blumstein Sheila E.
Published: October 2005

This paper attempts to define acoustic properties of laterals in English that are adjacent to vowels and in syllabic nuclei. When the tongue is in the lateral configuration, there is an increased bandwidth and decreased prominence of the second formant (due to increased losses) and some irregularities in the F3–F4 region (divided acoustic path). When a lateral consonant is produced adjacent to a vowel, there is a rapid change in the acoustic spectrum as these attributes appear or disappear. A series of acoustic analyses has investigated the nature of this discontinuity, particularly the change in amplitude and frequency of the first two spectral prominences. An abrupt change in F2 amplitude of about 10 dB at consonant release (less at closure) is a salient attribute. The attributes that distinguish a syllabic lateral and a nonlow back vowel /o/ have been examined through acoustic analyses and through perceptual experiments in which F2 bandwidth and other properties are manipulated in synthetic utterances. F2 bandwidth again appears to play a significant role in signalling this distinction. The common acoustic attributes associated with the lateral configuration appear to be used in different ways by listeners depending on the context. [Research supported in part by NIDCD.]
Analytical and numerical solutions of the ‘‘General Theory Scattering for the Scattering of Sound by Sound’’ in several useful limits
Authors: Woodsum Harvey C.
Published: October 2005

Integral equations which form the basis of ‘‘A General Theory for the Scattering of Sound by Sound’’ [H. C. Woodsum and P. J. Westervelt, J. Sound Vib. 76(2), 179–186 (1981)] have been solved in several useful limits. In the case of the parametric array, the theory is shown to reduce in the appropriate limit to the models of Blue as well as Berktay and Leahy, as corrected by Mellen and Moffett [J. Acoust. Soc. Am. 60, 581–583 (1976)]. In the case of intersecting sound beams, the theory is shown to agree with predictions by Westervelt, as well as recent experimental results on the nonscattering of sound by sound [R. Roy and J. Wu, in Proceedingsofthe 13thInternationalSymposiumonNonlinearAcoustics, edited by H. Hobæk (Elsevier Science, London, 1993)]. A by-product of the theory is a useful parametric array model for arbitrary primary field geometries; numerical results are presented which are compared to the computer model of Mellen and Moffett.
Plane-wave interaction with a sound pulse
Authors: Naugol’nykh K. , Rybak S.
Published: October 2005

The process of plane-wave scattering by a sound pulse was considered previously [D. Trivett and P. Rogers, J. Acoust. Soc. Am. 76, 1819–1822 (1984)]. Developing this approach, in the present paper the nonlinear scattering of a plane wave on a sound pulse containing a high-frequency carrier propagating at an arbitrary angle in respect to the direction of the plane-wave propagation is considered. It is shown that in addition to the combination tones in the scattered field the waves at Doppler frequencies appear. This feature of the process allows determination of the direction of plane-wave propagation by means of a nonlinear Doppler frequency response.
Hallowell Davis: A man for all of us
Authors: Eldredge Donald H. , Hirsh Ira J.
Published: October 2005

This paper reviews Davis’ education and scientific career, the many areas of science to which he contributed, the professional and public services that he rendered, and his assets as a colleague, mentor, and friend. He received the M. D. in 1922 from Harvard, where he served as teacher and scientist for 24 years. His early and persisting interests lay in the nervous system and its electrical potentials. During WWII his interests broadened to other aspects of hearing, including audiometry, noise exposure, functional test for otological surgery and design criteria for hearing aids. His second career, retaining many of those interests, began in 1946 when he went to Central Institute for the Deaf in St. Louis as Director of Research. He served actively in the U. S. government, the National Research Council, and the National Academy of Sciences and professional organizations, many of which honored him, and he was President of several. His contributions to the understanding of the physiology of the auditory system are known. Also known are important practical applications, the most recent of which was electric-response audiometry. He was a model for all of us—in science, teaching, clinical care, administration, civility, and personal integrity.
Hallowell Davis: What he meant to otology
Authors: Schuknecht Harold F.
Published: October 2005

It was a thrill to watch Hal manipulate stimulus parameters and recording instruments to encourage the guinea pig cochlea to reveal more of its secrets. He did not swerve from his conviction that alterations in the fields of electrical activity would reflect states of disorder in cochlear morphology and function that would one day have useful clinical applications. Hal was content, however, to allow others to struggle with the diagnostic and surgical challenges of otologic practice. I have no doubt that he could have been an outstanding clinical otologist but he felt rightly that for him a more useful contribution could be made to clinical medicine through research. By elucidating the bioelectric potentials of the auditory system he provided the basis for the development of the auditory evoked response (AER) test. The method differentiates cochlear from retrocochlear lesions with a high degree of accuracy. The use of AER to detect deafness in neonates has led to a more effective early management of profoundly deaf infants. Other devices that have benefited otology and can be attributed in part to discoveries and implementation by Hal Davis are electrocochleography, audiometry, and design and standardization of hearing aids.
Cochlear potentials and Davis
Authors: Dallos Peter
Published: October 2005

Before the advent of contemporary recordings of basilar membrane movements and intracellular responses from hair cells, cochlear potentials provided a means of deciphering cochlear mechanics and physiology. These gross potentials reflect extracellular currents produced by hair cells in response to sound, they consist of phasic and tonic components: The cochlear microphonic (CM) and the summating potential (SP). Davis and his colleagues pioneered the use of these responses to infer the properties of the traveling wave, to determine the sources of the various recordable response components and to probe their role in the hearing process. They also introduced various methods of artificially altering the cochlear environment in order to selectively modify responses and thus probe their properties. When examined in the light of more contemporary measurements, the early work appears remarkably prescient and enduring. [Work supported by the NIH.]
Hallowell Davis’ contributions to our knowledge of auditory-nerve activity
Authors: Kiang Nelson Yuan-sheng
Published: October 2005

The mammalian auditory nerve represents both the informational output of the ear and the input to the brain. Hallowell Davis was one of the pioneers in recording the electrical manifestations of auditory-nerve activity. He and his colleagues carried such studies from their virtual inception to eventual success in recording from single fibers and in so doing built a theoretical framework upon which to interpret data. Since his efforts, some of the physiological data have been expanded or corrected, new anatomical results have been incorporated and major revisions in theory have been proposed. Some of these advances have changed our understanding of how auditory-nerve responses arise and others have improved our understanding of what information is available to the central nervous system. This paper will review such progress including topics such as feedback mechanisms, comparative aspects, developmental ideas, and practical implications. Far from being an exhausted area for research, the auditory nerve continues to challenge experimentalists and theoreticians alike in posing problems that Davis foresaw but still remain unsolved.
Acoustic scattering by immersed circular cylindrical shell stiffened by internal lengthwise rib
Authors: Maze Gérard , Décultot Dominique , Klauson Aleksander , Metsaveer Jaan
Published: October 2005

The method of isolation and identification of resonances (MIIR) has allowed plotting of resonance spectra that characterize the shape, the structure, and the material of an object. On the spectra, the resonance peaks are related to surface waves propagating around the object. The backscattering, from thin-walled cylindrical shell stiffened by internal lengthwise rib and insonified normally to its axis, is studied. In the explored frequency band, the frequencies of S0 wave resonances are not much affected by the presence of stiffener. Measurements made during transient state after quasiharmonic excitation of the stiffened shell have shown that, at the S0 wave resonances, backscattering is maximum when the rib is located at the vibration nodes. In the total backscattered pressure, considering also forced vibration, the maxima are detected when the rib is in the antinodes. In the stiffened shell, other additional resonances appear that are not detected in the case of the unstiffened shell. These resonances are attributed to the flexural waves. They are the result of interaction of the rib and the shell at their structural joint. These additional resonances are better observed when the joint is located at the illuminated part.
An experimental apparatus for measuring underwater acoustic scattering from structurally complex finite cylinders
Authors: McCall George S. , Rogers Peter H.
Published: October 2005

Theoretical predictions of the scattering from submerged circular cylinders benefit from the simplicities inherent in the assumption of infinite length. Consequently, experimental verification of these predictions typically involves cylinders with high length to diameter ratios in order to approximate this assumption. However, there are obvious advantages in dealing with shorter targets. This paper describes an experimental apparatus for measuring the scattering from circular cylinders with length to diameter ratios of one. By minimizing the scattering from the endcaps and minimizing the extent to which the endcaps restrict the motion of the shell, the cylinder can be made to have scattering characteristics (in the plane perpendicular to its axis) similar to that of an infinitely long cylinder. Because larger diameters can be accommodated, a wide range of structural details can be more easily studied. Experimental results are presented for this shells, thin shells with ring supports, and ring supported thin shells with compliant outer layers. The experimental data are compared with numerical results from two- and three-dimensional computer models. [Work supported by ONR.]
The effects of voice and visible speaker change on spoken word recognition
Authors: Sheffert Sonya M.
Published: October 2005

It is generally agreed that listeners have a lexicon where words are stored as abstract types, rather than token instances. This assumption has led many researchers to posit ‘‘normalization’’ processes that strip away all but the abstract linguistic information represented in lexical entries from the acoustic signal. However, recent research finds that idiosyncratic speaker information, such as voice, is not discarded. For example, word recognition is facilitated when a word-voice pairing is preserved across study and test, suggesting that voice information is represented in memory and can serve as a retrieval cue for lexical access [e.g., Palmeri etal. (1983)]. Three experiments explored the effects of voice and visible speaker change on spoken word recognition using implicit and explicit memory measures. Subjects watched a videotape of speakers producing words. When a word was repeated, the visible speaker or his or her voice were either the same or different from the first presentation. Subjects performed a word recognition task. Some subjects were also required to explicitly encode either the speaker’s voice or face. The results demonstrate that detailed information about a talker’s voice and appearance is not lost during normalization, but is retained alongside the word in memory. [Work supported by NIH Grant No. HD-01994.]
Voice information in auditory form-based priming
Authors: Saldaña Helena M. , Rosenblum Lawrence D.
Published: October 2005

In auditory form-based priming, subjects are presented with speech stimuli that are phonetically related. Research has shown that a prime can facilitate recognition of a target item if prime and target share an initial phonetic segment. This facilitory effect has been considered either a result of residual activation of the initial phonetic representation [L. M. Slowiaczek and M. B. Hamburger, JEP: LMC 18, 1239–1250 (1992)] or post-perceptual guessing strategy [Goldinger etal., JEP: LMC 18, 1211–1238 (1992)]. It could be, however, that the facilitation is at least in part based on nonlinguistic auditory information. Previous studies have always used the same speaker for prime and target items. In the present investigation, auditory form-based priming experiments were conducted where voice information was changed from prime to target. Initial results reveal that varying voice information eliminates the facilitation effect. This could suggest that the effect is based on residual auditory activation. Follow-up experiments test whether eliminating the acoustic trace through backward masking attenuates the facilitation effect. Implications of these results will be discussed in terms of current models of spoken word recognition. [Work supported by NSF.]
Comparing reliability of perceptual and acoustic measures of voice
Authors: Rabinov C. Rose , Kreiman Jody , Gerratt Bruce R. , Bielamowicz Steven
Published: October 2005

Acoustic analysis is often favored over perceptual evaluation of voice because it is considered objective, and thus reliable. Specifically, jitter is frequently used as an index of pathologic voice quality because of its moderate to high correlation with vocal roughness. This study examined the relative reliability of human listeners and automatic algorithms in the evaluation of pathologic voices. Ten experienced listeners rated the roughness of 50 voice samples (ranging from normal to severely disordered) on a 75-mm visual analog scale. Rating reliability within and across listeners was compared to the reliability of jitter measures produced by several automatic voice analysis packages (CSpeech, SoundScope, CSL, and an interactive hand marking system). Results showed that overall listeners agreed as well or better than ‘‘objective’’ algorithms. Further, listeners disagreed in predictable ways, while automatic algorithms differed in seemingly random fashions. Finally, listener reliability increased with severity of pathology; objective methods quickly broke down as severity increased. These findings suggest that listeners and analysis packages differ greatly in their measurement characteristics, but that reliability is not a good reason for preferring acoustic to perceptual measures.
Numerical fluid flow model for predicting playing frequencies
Authors: Hoekje Peter L.
Published: October 2005

A numerical model is designed in order to predict playing frequencies of air reed instruments. The air reed mechanism is modeled by dynamically solving the Navier–Stokes equation for an incompressible fluid over a two-dimensional grid in the vicinity of the jet outlet, the edge on which the jet impinges, and a short distance into the main bore. The rest of the main bore is modeled as a quasi-one-dimensional waveguide, represented by an impulse response function. At the junction between the two parts of the model, the exciting wavefront is typically bulged, so the velocity distribution must be integrated over the bore cross section in order to calculate the excitation of the main bore. The results confirm that mode locking and octave overblowing occur in an instrument whose frequency response has nearly harmonic resonances, but not in one whose second resonance is much higher than twice the first resonance frequency. Comparisons of the resulting playing frequencies with experimental playing frequencies, and with those calculated by a simple passive model, will be presented.
Acoustical deflection of air jets
Authors: Nolle A. W.
Published: October 2005

Jets of stream velocity 8 to 20 m/s, 0.5 to 1.5 mm thick, are deflected by lateral flow either localized at the orifice or distributed as in an organ pipe. Synchronous hot-wire samples yield smoothly oscillating jet profiles to a downstream distance of some eight times the thickness. The frequency is 50 to 900 Hz. In disagreement with theory, the phase velocity of jet centerline displacement does not fall with decreasing frequency. For a parabolic velocity profile, this phase velocity rises near the orifice, remaining well defined. For a tophat profile the entry-zone velocity rise is more severe, but the phase velocity becomes ambiguous because the shear layers are unmerged, with out-of-phase varicose oscillations as predicted by Crighton. Lateral variation of velocity modulation phase is quite different for the two profiles. The phase of jet displacement relative to the acoustic pressure gradient is examined. The top-hat entry profile occurs in most flue organ pipes. A pipe with parallel-wall flue, giving the less usual parabolic profile, is demonstrated. In the zero-frequency limit, also studied, jet deflection is predictable from the momentum fluxes. Zero-frequency deflection produces jet self-centering in stopped pipes.
Z24-X-2 forty years later
Authors: Ward W. Dixon
Published: October 2005

In 1954, Exploratory Subcommittee Z24-X-2 of the American Standards Association issued a report entitled ‘‘The Relations of Hearing Loss to Noise Exposure’’ in which the first attempt was made to integrate the existing evidence concerning how exposure to industrial noise produced hearing loss. Although the subcommittee members were fully aware that limits of exposure would ultimately depend as much on political (social, monetary, and legal) considerations as on scientific evidence, it was judged worthwhile to try to provide as firm a scientific basis as possible for setting those limits. Considering the meager amount of reliable audiometric data that existed then, it is amazing how well their conclusions have been substantiated by subsequent evidence, even though those conclusions have sometimes been overridden by political forces. Present knowledge will be compared with some of the Report’s main aspects: the biological baseline; age corrections; additivity of noise-induced loss and age effect; individual susceptibility; contamination of data by temporary threshold shift; susceptibility of the already-damaged ear; and the inadequacy of total energy as a measure of exposure. Progress toward solution of a list of ‘‘unsolved problems’’ will also be summarized.
The relationship of the exchange rate to noise-induced hearing loss
Authors: Suter Alice H.
Published: October 2005

Terms such as ‘‘doubling rate’’ and ‘‘time-intensity trading relation’’ have given way to the ‘‘exchange rate’’ in recent years, which is the number of decibels permitted in a standard or criterion for each doubling or halving of exposure duration. Whereas most European nations, several Canadian provinces, and some U.S. agencies use the 3-dB exchange rate, the Department of Labor’s 5-dB exchange rate is widely used in the U.S. Many of the premises on which the 5-dB rule were based have proven to be faulty, and although it supposedly takes intermittencies into account, it actually allows uninterrupted exposures at relatively high sound levels. Evidence from studies of laboratory animals indicates that there is some reduction of threshold shift from intermittent exposures, yet epidemiological data do not support this concept in actual working conditions. The likely reason for this discrepancy is that industrial working conditions do not provide sufficient opportunity to recover from TTS. An analysis of the origins of the 5-dB rule, as well as evidence from field and laboratory studies supports the adoption of the 3-dB rule, with the possible addition of a small adjustment in the permissible exposure limit for certain outdoor occupations.
Occupational noise exposures with uneven temporal patterns
Authors: Shaw Edgar A. G.
Published: October 2005

ISO 1999:1990 presents procedures for predicting noise-induced permanent threshold shift as a function of noise exposure which is defined in terms of the equivalent continuous A-weighted SPL, LAeq,T over an average working day (assumed to be of 8-h duration) for a given number of years of exposure. Measurements are to be made with instruments capable of integrating high level impulses. These procedures are, of course, dependent on epidemiological data pertaining to the standard work week composed of approximately five 8-h work days. Nevertheless, daily exposure durations greater than 8 h and exposures that vary substantially from day to day are included in ISO 1999:1990, though subject to minor limitations. From another point of view, studies of temporary threshold shift, during and following exposure to steady noise for prolonged periods, seem to indicate that caution is justifiable. So, perhaps prolonged exposure durations should receive special treatment as suggested in the report prepared for the Special Advisory Committee on the Ontario Noise Regulation. [Work supported by APS707/NRCC No. 25051, Ottawa 1985.]
An examination of noise-induced hearing loss (NIHL) risk using a longitudinal hearing conservation database
Authors: Prince Mary M. , Smith Randall J. , Gilbert Steven , Stayner Leslie T.
Published: October 2005

Occupational hearing conservation programs (HCPs) have been implemented in many industries in accordance with the 1983 OSHA hearing conservation amendment. The availability of these longitudinal databases permits an examination of associations between changes in hearing levels with other variables, including noise exposure. This paper examined (1) whether there is an increased risk of NIHL from exposures below 85 dBA; (2) whether workers with noise exposures above 85 dBA who are required to use hearing protection still have an increased risk of NIHL compared to low-noise-exposed (less than 70 dBA) workers; and (3) how risk may depend on the type of hearing protection used and reported degree of compliance. The data used in this analysis include most of the data analyzed by the ANSI working group to examine hearing conservation program effectiveness. Variables included age, sex, race, type of hearing protection, industry code, and hearing threshold levels (for both ears, tested at 0.5, 1, 2, 3, and 6 kHz). Databases for comparison included both internal and external ‘‘control’’ groups with low-noise exposure, as well as noise-exposed populations in which either the hearing conservation program was highly effective and/or the population was well protected via good hearing protection compliance.
A study on the onset to chaos of hydrodynamic nonpropagating solitary wave motion
Authors: Miao Guoqing , Wei Rongjue
Published: October 2005

Previous experiments have shown that the onset to chaos would occur at points outside the stability region of the hydrodynamic nonpropagating soliton generated in a Faraday’s oscillating water tank driven harmonically [Wei etal., J. Acoust. Soc. Am. 88, 469–472 (1990)]. The purpose of the present paper will put emphasis for the first time on the study of the same phenomenon which occurred inside the stability region for those states that have strong stability. The present experiment is conducted in a rectangular water tank driven harmonically at (0,1) mode. Some observations include a single soliton in a very short tank, a double soliton, and a multisoliton, etc. Some porous materials were used at both ends of the tank to quench undesired resonant modes. For several tanks 10–35 cm long and 3 cm wide filled with water to a depth of 2 cm, a typical set of frequency spectrums have been obtained which show the transition from simple periodic to bifurcate, even to chaotic state intermittently. This experiment gives additional support to the idea that the chaos is out of order and the soliton is a form of order out of the potential chaos. [Work supported by National Scientific Foundation of China.]
Nonlinear wave propagation in a water-filled, conical shock tube
Authors: Buren A. L. Van , Luker L. D.
Published: October 2005

A conical shock tube is being developed for evaluating hull-mounted sonar transducers and related components for their vulnerability to exploding ordnance [J. F. Zalesak and L. B. Poché, Jr., Proc. 60th Shock and Vib. Symp. III, 73–76 (1989)]. A small explosive charge at the breech end generates a robust shock wave that travels down the tube and strikes the transducer at the muzzle end. Proper design of the water-filled shock tube requires an understanding of the nonlinear propagation of shock waves in a conical waveguide with nonrigid walls. This understanding is obtained by use of a numerical solution to the generalized Burgers’ equation [D. H. Trivett and A. L. Van Buren, J. Acoust. Soc. Am. 69, 943–949 (1981)]. Here the combined effects of nonlinearity, absorption, and dispersion are included in a stepwise calculation of the propagation. Results show that the effect of dispersion must be minimized to provide an acceptable shock waveform at the muzzle. Shock waves measured in a prototype shock tube are in good agreement with the theoretical predictions. [Work supported by ONR.]
Measurement of heat-exchange coefficients in an acoustic field
Authors: Mozurkewich G. , Murrell S. R.
Published: October 2005

Among the critical components of an efficient thermoacoustic device are its heat exchangers. This investigation was undertaken to determine whether it is reasonable to apply values of heat-exchange coefficients, h, estimated from well-known forced-convection correlations obtained in steady flow. The method involves suspending an element of the heat exchanger at a velocity antinode in a standing acoustic wave. Using Joule heating, the element is heated several degrees above the surrounding gas. Upon switching off the heating current, the element’s temperature (deduced from its electrical resistance) decays toward ambient. The value of h is extracted both from the amplitude and from the decay time. Measurement of h of single wires was chosen for the initial application of this method. Preliminary results have shown that the coefficient h decreases with increasing frequency to values substantially smaller than those estimated from steady-flow forced-convection correlations.
Reflection and transmission of a finite amplitude focused sound beam at a curved interface between two media
Authors: Makin Inder Raj S.
Published: October 2005

The talk will present further work on the interaction of a finite amplitude, focused sound beam with a curved interface separating two fluidlike media. An earlier presentation [Makin and Hamilton, J. Acoust. Soc. Am. 89, 1928 (1991)], had discussed the second harmonic generation in a focused Gaussian beam that is reflected from a slightly curved surface. As earlier, arbitrary absorption and complex surface impedance can be taken into account in the current model. The quasilinear analysis is now extended to a fully nonlinear numerical evaluation of the KZK equation using a finite difference method. An existing model for the free-field propagation of a high intensity focused sound beam [Tjo/tta etal., J. Acoust. Soc. Am. 89, 1017–1027 (1991)], has been modified to evaluate the fields reflected and transmitted from a curved interface between two media. Propagation curves, beam patterns, phase plots, and time waveforms for various parametric combinations of source conditions and media pairs are presented, highlighting the effect of the interface curvature on the reflected and transmitted beams. Significance of the work in terms of biomedical applications is discussed. [Work supported by NSF and the David and Lucile Packard Foundation.]
Emerging shallow water ocean acoustic research activities at the Naval Surface Warfare Centers’ Fort Lauderdale facility
Authors: Venezia William A.
Published: October 2005

An overview of the emerging shallow water ocean acoustic research activities at the Naval Surface Warfare Centers’ Fort Lauderdale Facilities is described. A recent facility realignment under the Signatures Directorate of the Naval Surface Warfare Centers, Carderock Division and subsequent mission addition to ship silencing is also described. The facilities now have the ability to provide the most detailed acoustic data possible. Recent advances in the methods used to conduct surface ship and submarine acoustic trials are described. Government, university, and private sector shallow water acoustic research programs using the range are presented. Specific information on use of the Naval facility for ocean acoustic research is given. A description of the test and evaluation environment is given including a detailed description of the climate and ambient acoustic noise of the shallow water off Fort Lauderdale. Facilities’ descriptions include location, the staff, contract support, and support of other activities. A description is given of the test ranges, test types, tracking techniques, marine facilities, and support craft. A description of the major shop facilities and logistic support available is given.
Characteristics and seasons of blue and finback whale sounds along the U.S. west coast as recorded at SOSUS stations
Authors: Cummings William C. , Thompson Paul O.
Published: October 2005

Blue whale sounds were doublets, each member lasting about 19 s. ‘‘A’’ sounds mostly occurred at 19.7 Hz; ‘‘B’’ at 22.2 with a short tail at 19.8. A few individual whales appeared to call for hours or perhaps days within hydrophone range with a constant background din of like signals. Sounds occurred in June–December, peaking as a high-level chorus in September–October and increasing ambient noise up to 20 dB. Interseasonal occurrence patterns at the same stations were remarkably similar. There was no clear evidence of longitudinal migration in the broad area, Mexico–Canada. These sounds, compared with subsequent blue whale recordings elsewhere, strongly suggest a dialect. Finback sounds mostly were doublets, each lasting about 1 s. The first member shifted downward (25.5–15.6 Hz) as did the second (34.6–17.5 Hz). Intervals between signals of a series varied from 9–21 s. Finback sounds were rare in summer, but numerous in the form of winter and spring choruses after nearly all blue whale sounds ceased. Localizations showed that the finbacks swam about 6 kn, and they had a source level of 183 dB re: 1 μPa, 1 m. Assuming even rough correlation between numbers of whales and sounds, SOSUS was able to reveal the seasonal occurrence and abundance of blue and finback whales over the entire western U.S. coastal region.
Non-Rayleigh statistics of ultrasonic backscattered echo from tissues
Authors: Narayanan V. M. , Molthen R. C. , Shankar P. M. , Reid J. M.
Published: October 2005

The envelope of the backscattered signal from tissues can exhibit non-Rayleigh statistics if the number density of scatterers is small or if the variations in the scattering cross sections are random. The K distribution which has been used extensively in radar, is introduced to model this non-Rayleigh behavior. The generalized K distribution is extremely useful since it encompasses a wide range of distributions such as Rayleigh, Lognormal, and Rician. Computer simulations were conducted using a simple one-dimensional discrete scattering model to investigate the properties of the echo envelope. In addition to cases of low number densities, significant departures from Rayleigh statistics were seen as the scattering cross sections of the scatterers become random. The validity of this model was also tested using data from tissue mimicking phantoms. Results indicate that the density function of the envelope can be modeled by the K distribution and the parameters of the K distribution can provide information on the nature of the scattering region in terms of the number density of the scatterers as well as the scattering cross sections of the scatterers in the range cell. [Work was supported by NSF Grant No. BCS-9207385.]
Time domain acoustic absorption: A unified model for linear and nonlinear acoustics
Authors: Rolt Kenneth D.
Published: October 2005

Dissipation of a linear acoustic wave, at frequency ω0, is directly related to the pressure absorption coefficient α(ω). In the viscous case, α(ω)=(4/3η+ηb)ω20/(2ρ0c3). For an initially ω0-sinusoidal large-amplitude nonlinear wave, the absorption coefficient is usually described by a linear part, and by an excess part related to the harmonics from nonlinear distortion. An alternate way to describe the absorption of a nonlinear acoustic wave is to define a total absorption coefficient. This is done in the time domain directly by considering dissipation in the momentum equation, and then proceeding in an energy balance approach. The result gives the instantaneous α for a given point on the wave in space without the need for spectral decomposition. For the viscous case, α(x) = (4/3η + ηb)‖∇2ν‖x0‖/(2ρ0c‖ν0‖), where ν is the particle velocity and x0 is the evaluation site. For harmonic dependence, this reduces to the preceding value α(ω). Similar procedures yield α(x) for heat conduction and relaxation. Examples will be shown for the propagation of linear and nonlinear waves, in water, and in a relaxation-type tissuelike rubber. [Work supported by C. S. Draper Laboratory.]
Field measurements for an intra-arterial angioplasty device
Authors: Makin Inder Raj S. , Carr Everbach E.
Published: October 2005

Ultrasonic angioplasty devices awaiting FDA approval are being developed for the removal of atheromatous plaque in peripheral and coronary arteries [abstract, O. K. Colliou and E. C. Everbach, J. Acoust. Soc. Am. 93, 2330 (1993)]. This talk presents the results of work in progress on characterizing the acoustic field due to a vibrating ultrasonic catheter wire (MedSonic, Inc., New York), which is a second-generation device with a titanium spherical tip at its end. Changes in the radiation characteristics of the system operating at 22.2 kHz (cw) will be discussed, based on varying the system parameters. Results will be presented from wires with different ball-tip diameters, different driver intensity settings, and varying viscosities of damping fluid in the wire sheath. By determining the acoustic field of the device, the probable regions of cavitational activity responsible for the bioeffects observed clinically can be identified. [Work supported by NSF MSS-9253777.]
Nonlinear behavior of electroacoustic transducers
Authors: Sherman Charles H. , Butler John L.
Published: October 2005

An important goal of electroacoustic transducer development has long been maximization of the acoustic output power for a given transducer size. This goal always encounters familiar material mechanical, electrical, magnetic or thermal limitations—all the ultimate effects of nonlinear behavior. However, other nonlinear effects, such as harmonic distortion and instability, are the practical operational limitation in some applications, making nonlinear analysis an essential part of the process. Most basic transduction mechanisms are strongly nonlinear and all have some nonlinearities. Fortunately, the nonlinearities in all transducers have similar features and can often be represented in identical mathematical forms even when physically different. This study identifies the nonlinear features which are common to all major types of transducers (electrostatic, variable reluctance, piezoelectric, electrostrictive, magnetostrictive, and moving coil). Recognizing these common features makes it possible to develop nonlinear solutions which apply to all types of transducers and facilitates comparison of transducer types for susceptibility to nonlinear effects. Recently published perturbation solutions obtained for moving coil transducers [J. Acoust. Soc. Am. 94, 2485–2496 (1993)] will be generalized and used to illustrate evaluation of harmonic distortion in other transducers.
The importance of coupling factor for underwater acoustic projectors
Authors: Moffett Mark B. , Marshall William J.
Published: October 2005

Underwater sound projectors are usually operated near a resonance frequency in order to radiate high power at a reasonable efficiency. The width of the resonance peak is inversely proportional to the mechanical quality factor, Qm, and therefore the bandwidth of a projector is often said to be determined by Qm. However, an equally important parameter affecting the bandwidth is the effective coupling factor, keff. The connection between bandwidth and coupling factor, although expressed by Warren P. Mason in 1948, has not been generally appreciated by transducer designers and users. Recently, however, Dennis Stansfield [UnderwaterElectroacousticTransducers (Bath U. P. and Inst. of Acoust., Bath, UK, 1990)] has elucidated this connection, showing explicitly how power amplifier and projector properties combine to determine practical bandwidth limitations. If the acoustic output of the projector is field-limited (i.e., by a maximum allowable drive field), the effective coupling factor furnishes a useful design starting point. Knowledge of typical values for keff for various transducer classes permits initial sizing of the transducer active material. [Work sponsored by the Office of Naval Technology.]
Design approaches to high power class III (inverse barrel stave) flextensional projectors
Authors: Porzio Raymond , Harvey Peter G. , Wason Charles P. , Bernier Gerald L.
Published: October 2005

Inverse barrel stave or class III flextensional projectors provide the designer of flexural low frequency projectors with an alternative high efficiency, high power density, broadband source which is less sensitive to service life limitations due to long term creep associated with ceramic stacks in other flextensional types. Other benefits arise from the stress-biased concave stave shell which undergoes a reversal in the sign of static stresses as the projector descends in depth resulting in greater shell strength margins allocated to dynamics. Results from combined electroacoustic modeling, finite element analysis and measurements show that, unlike convex shell flextensionals, shell wall thickness has only a very weak influence on resonance frequency and coupling. Instead, the R/L ratio (defined as the radius of curvature of the stave shell normalized by the ceramic stack length) exerts a surprisingly strong influence on the projector’s frequency response and performance metrics. [Work supported by SPAWAR and NCCOSC, San Diego.]
Electrostrictive polyurethane projector
Authors: Barger James E.
Published: October 2005

Projectors for the acoustical radiator for tactical search (ARTS) program must be very thin, to minimize drag, while at the same time produce large surface displacements in the 70- to 300-Hz band. To accommodate these requirements, the projectors are flat pads of thickness 0.1 m laminated from 1400 layers of polyurethane film that has deposited, on one side, a 300-Å aluminum electrode. The individual projector pads are to be arrayed in a self-propelled vehicle that is 100 m deep, 3 m long, and 0.2 m wide, and that is capable of stable operation to 15 kn. Polyurethane was chosen for the transduction material mostly because of its small modulus (15 MPa) and large displacement coefficient (10 Å/V). The low-Q resonance for an individual projector pad, determined by the stiffness of the pad and radiation mass, occurs at about 200 Hz; but this frequency is expected to be lowered to 150 Hz for the array of projectors, owing to a greater radiation mass. Since polyurethane film has not before been used as a transduction material, its electrostrictive and mechanical properties are described. The projectors are fabricated in the manner of polymeric film capacitors, with some modifications.
Producing a distortion-free output from a PMN/PT transducer using large driving voltages
Authors: Forsythe S. E. , Piquette J. C.
Published: October 2005

PMN/PT (lead magnesium niobate/lead titanate) is an electrostrictive ceramic that exhibits high strains when an unpoled sample is subjected to a high voltage. The strain as a function of voltage is an almost perfect square law, s=kV2, over a large range of voltages, neglecting higher-order effects such as hysteresis and saturation. This response suggests that a transducer made of PMN/PT should be driven using an ac signal superimposed upon a large bias voltage. The bias voltage is needed to achieve a large effective strain/volt in response to the ac signal. If the ac signal amplitude is greater than a few percent of the bias voltage, significant distortion appears in the output due to the nonlinear response. To achieve the full potential response of this material, it is desirable to shape the driving signal such that the ac voltage swings over nearly twice the bias voltage while faithfully reproducing the desired signal at the output. Techniques for accomplishing this, even when the desired signal is complex or transient, by using models and their inverses are discussed and experimental results are presented. [Work supported by Office of Naval Research.]
Applying the reactive power approach to the woodwind instruments
Authors: Boutillon Xavier
Published: October 2005

The time-domain approach of self-sustained instruments such as the violin or the clarinet has sometimes revealed a marked hysteresis between force or pressure and velocity or flow. Formally defined by analogy with the active power, the reactive power Qn=nπpnfn sin(φn) injected by a component into a pipe is highly sensitive to phase differences between pressure and flow components. The reed dynamics is one major cause for hysteresis; under various assumptions, the reed stiffness will be expressed as
A mathematical formulation for modeling the type I fuzzy parameters for a continuous line fuzzy attachment
Authors: Russell Daniel A. , Sparrow Victor W. , Soize Christian
Published: October 2005

This talk will summarize the results of an exchange during the summer of 1993 between Penn State University and the Office National d’Etudes et de Recherches Aérospatiale. The mutually agreed goal of this exchange was to develop a mathematical method for modeling the parameters of a line fuzzy attachment. A model fuzzy was developed for an attached plate in bending mode only using the type I fuzzy law. (The three fuzzy parameters in the type I law are mass, critical damping, and modal density.) The coupling between the attached plate, modeled as a fuzzy, and the master structure is purely through rotation about the attachment position. As a first approximation using the type I fuzzy law, all of the random dispersion parameters were assumed to be zero, and the focus of the method was to determine the mean values of the fuzzy parameters. The fuzzy damping rate and modal density can be found directly from the plate parameters. The fuzzy mass cannot be determined directly, and the mathematical formulation centered on how one might find this mass. [Work supported by ONR and ONERA.]