bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid flow imaging by means of wide-band diffraction tomography
Authors: Norton Stephen J.
Published: July 2002

The problem of reconstructing a two-dimensional distribution of fluid flow from wide-band scattering measurements is considered. Reciprocal scattering measurements are employed, meaning that scattered waves are recorded between a source and receiver, and again with the source and receiver interchanged. As shown, such measurements allow the reconstruction of a fluid flow image separate from that of a distribution of stationary acoustic velocity inhomogeneities.
Comments on “Acoustic wave propagation through porous media revisited” [J. Acoust. Soc. Am. 100, 2949–2959 (1996)]
Authors: Smeulders D. M. J. , Sorek S. , van Dongen M. E. H.
Published: July 2002

In a 1996 paper by T. W. Geerits, published in this Journal, it was claimed that a new theory for acoustic wave propagation in porous media was derived. It will be shown that this claim is not justified. Correct application of the averaging procedures and correct interpretation of the dissipation leads to a one-to-one agreement with the Biot theory, which was published in this Journal in 1956 [M. A. Biot, J. Acoust. Soc. Am. 28, 168–178, 179–191 (1956)].
Seabed sediment attenuation profiles from a movable sub-bottom acoustic vertical array
Authors: Frazer L. Neil , Fu Shung-Sheng , Wilkens Roy H.
Published: July 2002

The acoustic lance [S. S. Fu, M.Sc. Thesis, University of Hawaii at Manoa (1994); Fu et al., J. Acoust Soc. Am. 99, 234–241 (1996)] consists of a linear array of acoustic receivers below an acoustic source, all mounted on the outside of a core barrel or independent probe which is embedded in the seafloor. In earlier studies lance travel time data were processed to give in situ compressional wave sound speed as a function of depth. In this study lance waveforms are processed to extract compressional wave attenuation A=Q−1 as a function of depth. The processing technique is unusual because the L1 norm is used instead of the usual L2 norm, the model space of attenuation profiles is exhaustively searched within the limits of discretization, and the marginal posterior probability density function of attenuation is computed explicitly at each depth. The technique is described in terms of Bayesian inverse theory using the notation of Tarantola.
Vocal production mechanisms in the budgerigar (Melopsittacus undulatus): The presence and implications of amplitude modulation
Authors: Banta Lavenex Pamela
Published: July 2002

In this paper acoustic evidence is presented for the presence of amplitude modulation in budgerigar (Melopsittacus undulatus) contact calls and learned English vocalizations. Previously, acoustic analyses of budgerigar vocalizations have consisted solely of visual inspection of spectrograms or power spectra (derived from Fourier transformation). Such analyses have led researchers to conclude that budgerigar vocalizations are primarily frequency-modulated, harmonic vocalizations. Although budgerigar calls have been shown to contain regions that are modulated in amplitude, the implications of this fact have been largely ignored. Amplitude modulation, the nonlinear interaction between two separate signals that results in the creation of new, heterodyne (sum and difference) frequencies, can produce a very complex Fourier spectrum that may resemble that produced by a harmonic vocalization. In this paper, the acoustic principles necessary for identifying amplitude modulation present in signals are outlined, and followed by data demonstrating that amplitude modulation is a prominent feature not only of natural budgerigar contact calls, but also of their learned English vocalizations. It is illustrated how analyzing a vocalization that contains amplitude modulation as if it were harmonic can result in misinterpretations of the acoustic and physical properties of the sound and sound source. The implications of amplitude modulation for studies of the ontogenetic, physical, and neural basis of budgerigar vocalizations are discussed, and a potential model for how the budgerigar syrinx may function to produce amplitude modulation is proposed.
Formulation of the interaction of guided waves with buried structures in the shallow ocean
Authors: Werby M. F.
Published: July 2002

In this work the interaction of a guided wave with a buried object is formulated based on a unified propagation-object scatter model. The model makes use of a range-dependent normal mode description of propagation and a t-matrix approach to scattering. In a sediment, certain modes may propagate into the bottom, while others never penetrate and the remaining modes attenuate quickly into the bottom. These facts are used to derive a mathematically plausible method that also has the advantage of yielding intuitive information. Here ocean refraction, boundary interaction at the water-bottom interface, and absorption in the sediment are taken into account. Since this formulation makes use of general t matrices there is little limitation on the type of targets that may be considered at the bottom. A result from this formulation is the expected angular spectrum and their weights, which are useful for the experimentalist.
Building a bottom scatter database from measured bottom scatter data in the eastern Mediterranean Sea
Authors: Neumann Peter , Muncill Gregory
Published: July 2002

The current U.S. Navy Standard bottom scatter database for low frequencies (up to 5 kHz) is Lambert’s Law with a mu coefficient of −27 dB for the world. In recent years, work to characterize scattering from both rough interfaces and the sub-bottom volume has greatly increased the understanding of acoustic interaction with the ocean bottom. However, the analysis of measured bottom scatter data requires an approach that includes the effects of the measurement geometry, higher-order multipaths, and contributions from the water-sediment interface, sub-bottom volume, and the sediment–basement interface. The SCARAB (scattering and reverberation from the bottom) model along with an automated inversion approach (simulated annealing with a downhill simplex) is designed to invert measured bottom scatter data for seven bottom scatter parameters. These seven parameters characterize the water–sediment interface, sub-bottom volume, and sediment–basement interface using a spectral representation for each. The SCARAB model is being used to analyze bottom scatter data measured by navoceano in the Eastern Mediterranean Sea and produce a database for prediction of bottom scattering strength for active sonar systems. The database is to be submitted to the OAML-SRB in late 1999. [This work is being sponsored by SPAWAR (PMW-185) under ONR management.]
Local performance recording and reproduction: Application to a string quartet
Authors: Hartmann William M. , Constan Zachary A.
Published: July 2002

A goal of traditional multichannel sound recording is to transport the listener into the environment of a musical performance. Ideally, the sound field at the ears of the listener resembles the sound field of a live performance, including ambiance cues to the acoustical character of the performance space. The goal of the local performance recording and reproduction technique (LPR/R) is the reverse. It attempts to transport the music into the environment of the listener. In this technique both the recording and the reproduction steps are different. The LPR/R technique requires at least one separate recording channel for each musical instrument. Recorded channels contain no crosstalk among instruments and no reflected sound from the room surfaces. On reproduction, the channels from different instruments are similarly kept separate; they are never electrically mixed. Instead, the channel(s) for each individual instrument are reproduced by a dedicated array of loudspeaker drivers, attempting to simulate the radiation pattern of the instrument. The LPR/R technique is particularly suited to small ensembles. Listening tests show that it is especially effective when the listener moves. An eight-channel application of the technique to a Mozart string quartet is described and demonstrated.
Passive acoustical survey of finless porpoises in the Yangtze River, China
Authors: Akamatsu Tomonari , Wang Ding , Wang Kexiong
Published: July 2002

Finless porpoises (Neophocaena phocaenoides) are distributed in Asian waters. The narrow-band and high-frequency pulse sonar signals produced by this species are distinctive from background noises. Underwater sound monitoring by a hydrophone (BK8103) along board sides of a research vessel concurrent with visual observation were conducted in the Yangtze River from Wuhan to Poyang Lake in 1998. The peak-to-peak detection threshold level was 133 dB re: 1 μPa, which could be roughly converted to the theoretical detection range of 316 m, hypothesizing the porpoise directing to the hydrophone and 168-dB source level of the sonar signal under a shallow water sound propagation (combination of spherical and cylindrical spreading). In a total of 1064-km cruise, 717 finless porpoises were observed. The acoustical monitoring system could detect the sonar signals from finless porpoises, found within 200 m from the research vessel. The sonar signals could also be detected at night and under windy weather conditions. Basically, the acoustical observation system was operated automatically and free from the individual difference of observers. The high-frequency acoustical monitoring seems to be an effective method for the survey of small cetaceans which produce sonar signals.
Acoustic sensors and NDE techniques for process control in drug, cosmetic and food manufacturing industries
Authors: Tavossi Hasson M.
Published: July 2002

New techniques of acoustic sensors for process control in manufacturing industries are presented. Two practical applications of acoustic sensors are considered. The first case involves remote determination of bulk-temperature of a paste heated in an agitated mixer, when other means for temperature measurement are not tolerated. During chemical processing the precise value of bulk-temperature of the paste must be known for quality control of the final product. To determine bulk-temperature, thermal expansion of a rod, placed in the mixer, is measured by acoustic sensors, in the pulse-echo and the through-transmission modes. The results show that in the range of 60°F–210°F a temperature change of 1°F can be measured. The second case relates to the nondestructive measurement of the solid content of the packaged food products. Accurate value of the solid-weight-ratio is required for correct thermal processing. Nondestructive methods with acoustic sensors in the through-transmission mode are utilized to measure solid-weight-ratio of a binary mixture of water and a food product. Using Wood’s equation for porous media, a precision of less than 5% in the value of solid-weight-ratio is obtained by this new technique.
Effect of a tracheal tumor on breathing sounds: A case study
Authors: Kraman Steve S. , Harper Paul , Pasterkamp Hans , Wodicka George R.
Published: July 2002

A 67-year-old man came to the hospital with a history of shortness of breath on exertion and cough progressing to severe breathlessness at rest over several weeks. Physical exam revealed stridorous sounds in inspiration and expiration heard at the mouth and over the trachea. Lung function tests revealed severe airway obstruction in expiration and probably inspiration. Fiberoptic airway inspection revealed a large mass above and arising from the main carina (first airway bifurcation). This mass obstructed the distal trachea except for a narrow (∼2 mm) circumferential space between the mass and the tracheal wall. Breathing sounds were recorded from in front of the mouth and the anterior neck overlying the trachea both before and after laser ablation of the mass. Before ablation, the tracheal sound exhibited unusual resonances and antiresonances that rose in frequency by nearly 100% during inspiration and fell during expiration. These variable sounds disappeared after laser ablation of the mass. It is postulated that the mass behaved as a dynamic acoustic obstruction and thereby altered the distal boundary condition and resonance behavior of the respiratory tract during breathing. This provides insights into the links between the airway anatomy and measurable acoustic properties of breath sounds.
Wireless hearing aid compatibility—handset testing requirements
Authors: Berger H. Stephen
Published: July 2002

The Hearing Industry and Wireless Industry has been working together since 1996 to develop a standard to resolve this issue. This paper reports on the technical challenges and the testing requirements for wireless handsets. It concludes with a brief discussion of the need for consumer education and involvement in order to achieve the optimal solution to this issue. Hearing aids operate in two modes. In their primary mode a microphone is used to sense acoustic signals. The secondary mode uses an inductive coil, known as a T-Coil, to receive a magnetic signal which has been modulated by the audio signal. For the wireless handset, which may be used with a hearing aid, there are test requirements arising from both modes. The field strength of both the E and H field, in the area intended for use by a hearing aid must be measured and assured to be within specified parameters. For the T-Coil mode a magnetic signal, modulated by the audio, must be assured. However, in T-Coil mode there is also the issue of assuring that the signal has sufficient quality and does not suffer from magnetic interference from secondary sources.
Notes on nonlinear elasticity of rocks
Authors: Ostrovsky Lev A.
Published: July 2002

Recent experiments with samples of Earth materials such as sandstone have shown that they possess a strong nonlinearity, and that water saturation, even in small amounts, may strongly affect nonlinear properties of the material. Here, a theoretical model is considered which represents the rock as a conglomerate of ‘‘large’’ grains (of order 100 μm) with two types of contacts: hard ones which determine the basic elastic matrix, and soft contacts, due to much smaller contacting grains which can create strong nonlinearity. Also, the effect of capillary and Van der Waals forces in thin liquid layers between grains is considered. The theoretical estimates are compared with available experimental data.
Wind generated sound in standing corn
Authors: Browning David G.
Published: July 2002

The ‘‘sound of corn growing’’ in farming folklore appears to be due to wind puffs, during otherwise calm conditions (especially at night), causing isolated audible popping sounds due to leaf striking leaf [D. G. Browning, Am. J. Botany 84, 38(A) (1997)]. When the wind becomes steady, the number of events greatly increases, resulting in a rustling sound with a smoothed, broad spectrum between 1 and 5 kHz, and a peak at 2.5 kHz. For a windspeed of 20 mph the peak level is 20 dB above ambient. As the corn matures, the increased weight of the corn ears causes greater stalk sway at a given windspeed; also the leaves tend to become more brittle due to reduced moisture content. Both of these changes appear to alter the measured sound spectra, offering a means for evaluation.
Spectral broadening of sound scattered by atmospheric turbulence
Authors: Goedecke George H. , Wood Roy C. , Auvermann Harry J. , Ostashev Vladimir E.
Published: July 2002

Scattering of a monochromatic sound wave by atmospheric turbulent eddies that are moving with the mean wind is described. The source and detector have wide radiation patterns and are at rest in a ground fixed frame. For eddies that make the dominant contribution to the detector signal, scattering angles change substantially with time, so the signal displays a time-dependent frequency which may include the full longitudinal Doppler width. A computer code is developed that calculates the time-dependent detector response and its Fourier spectrum due to one or many eddies, including a steady-state collection of eddies of many different scale lengths that models homogeneous and isotropic atmospheric turbulence. Several numerical results from this code are presented, including one for a simulation of a recent experiment. The predicted spectral characteristics are in very good agreement with the experimental ones. Some possible extensions of the model for describing anisotropic and intermittent atmospheric turbulence are discussed. [Work supported in part by the U.S. Army Research Office under Contract Nos. DAAG55-98-1-0463 and DAAG55-97-1-0178, and an NRC-ETL Research Associateship.]
Detectability of Gaussian noise by humans and simulated observers: A stimulus-level correlation analysis
Authors: Lapsley Miller Judi A.
Published: July 2002

The correlation between ratings made by humans and simulated observers in detecting the same acoustic stimuli was used to estimate the detection (critical) bandwidth, and the form of rectification, temporal integration, and sampling strategy used by the human hearing system. By using small-WT Gaussian noise, bandwidth (W) and duration (T) were manipulated independently, resulting in 18 different combinations of bandwidth and duration for WT=1, 2, and 4. The pattern of correlation, as properties of the simulated observer were systematically varied, indicated the best correlated observer. This tended to be the full-linear observer, consisting of a bandpass filter (which was generally wider than the bandwidth of the signal), full-wave rectifier, and a full (true) integrator. The full-linear observer was slightly, but consistently, better at describing human performance than the energy or envelope detector.
Searching for foreign accent
Authors: Bond Z. S. , Stockmal Verna , Moates Danny R.
Published: July 2002

Native speakers of English can identify non-native speakers with relatively little difficulty. Further, they claim to be able to identify the native language of non-native speakers, at least as suggested by such descriptive terms as French accent or Arabic accent, implying that non-native English carries properties which are characteristic of native languages. In four experiments, we investigated whether English speakers could match an unknown foreign language with a foreign accent. In the first two experiments, listeners heard a sample of accented English and were asked to identify the native language of the speakers from a series of competitors. The target languages were Japanese and Latvian. Listener performance did not exceed chance. In the third experiment, listeners made ‘‘yes–no’’ responses to accented English matched with foreign languages, including the native language of the speaker. Although listeners thought some languages were more likely to be the source of the foreign accent than others, they did not identify the target language correctly. In the fourth experiment, listeners made ratings on a seven-point scale, judging the similarity of accented English and various foreign languages, with results very similar to those of experiment 3.
The effect of duration on the perception of Cantonese level tones
Authors: Wong Patrick C. M. , Diehl Randy L.
Published: July 2002

An inverse relationship has been claimed to exist between the pitch of phonemic tones and the duration of the tone-bearing syllables [e.g., Blicher et al., J. Phonetics 18, 37–49 (1990)]. If this generalization is correct, syllable duration might be expected to serve as a perceptual cue to tone category. In this study, Cantonese-speaking listeners identified tones in sentence context. A naturally produced Cantonese sentence (/ha6 yat1 go3 zi3 hai6 si3/ ‘‘The next word is to try’’) was resynthesized in 25 versions such that the fundamental frequency (F0) contour of the context (the first five syllables) was shifted upwards, 1%, 3%, 6%, 9%, or 12% relative to the original, and the final, target syllable was resynthesized with durations that were 80%, 90%, 101%, 110%, or 120% of the original. We predicted that the higher context F0s and longer target syllable durations would yield more low-tone identification responses. The results of an analysis of variance showed a significant main effect of contextual F0 in the expected direction, but no significant effect of target syllable duration. This last result calls into question the generality of the assumed perceptual relationship between duration and tone category. [Work supported by NIDCD.]
Perception of English sentence stress by Yarmouk University English majors
Authors: Mitleb Fares , Al-Haq Fawwaz , Al-Jarrah Rasheed
Published: July 2002

Perception of English sentence stress at discourse level was the focus of the present paper. Twenty English majors, freshmen and seniors at Yarmouk University, voluntarily took part in the study. In the scope of this paper, it was assumed that the subject would give diverse responses on the test material which comprised 13 English utterances, each of which was produced with the correct stress pattern by native speakers of American English. The subject’s dependence on their native language perceptual pattern (i.e., Arabic in this case) made them fail to take advantage of the auditory correlates of stress such as pitch, duration, and loudness in the most appropriate way. The subjects’ task was to mark out the constituent made most prominent by the native speaker in each utterance. Their responses were then classified as normal (if stress was correctly perceived), contrastive (if it was perceived on a different constituent), or undecided (if the utterance was perceived unstressed altogether or if two constituents or more were stressed simultaneously). It turned out that the subjects sometimes perceived stress on constituents that are hardly stressed such as pronouns; determiners and prepositions made it clear that the subjects’ mastery of the phenomenon under discussion was inadequate.
The discrimination of Mandarin Chinese alveolo-palatal fricative and affricate contrasts by American English and Mandarin Chinese speakers
Authors: Tsao Feng-Ming , Liu Huei-Mei , Kuhl Patricia K.
Published: July 2002

This study examined how language experience affects the perceptual sensitivity of adult speakers to nonnative phonetic contrasts. Three of Mandarin contrasts (two alveolo-palatal fricative versus affricate contrasts and one alveolo-palatal affricate aspirated versus unaspirated contrast) were computer synthesized. For each of these three contrasts, three different variations were contrasted by varying either amplitude rise time or fricative noise duration. Both English and Mandarin speakers participated in a speech discrimination task using these stimuli. When compared to the performance of Mandarin speakers, English speakers showed poorer performance for each stimulus pair in terms of accuracy and sensitivity measures (d′). However, both English and Mandarin speakers demonstrated similar difficulty when tested with three stimulus pairs that were not typical exemplars of Mandarin phonetic categories. The results show the effect of language experience on the discrimination of phonetic contrasts. [Research supported by NIH grant to P. K. Kuhl.]
Correlation between vowel production and perception for a given speaker
Authors: Hombert Jean-Marie , Carre Rene
Published: July 2002

The goal of this paper is to investigate the correlation between production and perception of 10 French oral vowels at the individual level. Acoustic data (F1, F2 and F3) from 10 French native speakers were collected. Measurements were obtained from the mid-point of the vowels using cepstral analysis. Each vowel was represented by 10 measurements. The same 10 speakers were subjected to perceptual experiments in which 53 synthetic vowel stimuli covering the entire vowel space were presented through headphones. The subject’s task was to identify which French word from a list of 10 words (from the same list used in the production experiment) representing the 10 French oral vowels. Each synthetic stimulus was presented 10 times in randomized order. Subject responses were mapped in a F1-F2 space with groupings corresponding to 90% of identical labeling. These perceptual results were compared with the measurements obtained from the production data. Our results show that the target values in the perceptual domain are correlated for a given subject with this production data. This conclusion is extremely important for understanding how individual variations within the same Linguistic Community can be the source of sound change. [Work supported by CNRS-GDR Cognition and Linguistic Diversity.]
Analysis of voice onset time in Georgian
Authors: Wysocki Tamra M.
Published: July 2002

The Georgian stop system has a three-way opposition: voiced, voiceless aspirated, and voiceless ejective. This paper reports on results from an analysis of voice onset time (VOT) in word-initial stop consonants preceding /a/. Two native speakers of Georgian (one male, one female) were recorded reading two randomized token lists: one containing nonsense syllables (e.g., ‘‘ba’’) and one containing actual Georgian words (e.g., ‘‘balaxi’’ ‘‘grass’’). Tokens were repeated twice. VOT values were measured using spectrograms and waveforms. Results show that VOT clearly distinguishes two categories in Georgian: voiced and voiceless. Initial voiced stops had short positive VOTs, while the initial voiceless stops had relatively long positive VOT values. Within the voiceless category, however, mean VOT values for ejectives and aspirates overlapped. Articulatory and acoustic characteristics of ejectives and aspirates are discussed in relation to other possible cues for distinguishing between the two types of stops. In addition to stop categories, the results show a trend toward another distinction: place of articulation. Labials had the lowest VOT values, followed by coronals, and then velars. The results from these analyses are compared to studies of voice onset time in other languages.
Cross-spectral methods with applications to speech processing
Authors: Nelson Douglas J.
Published: July 2002

Cross-spectral methods were first presented in the mid-1980’s as a method for accurately estimating stable parameters such as modem baud rate and carrier frequencies. The stability of these signal parameters makes it possible to integrate large amounts of data to accurately estimate parameters even under degraded conditions. Since biological signals, such as speech, are not stationary, classical analysis methods, including normal cross-spectral methods, are poorly suited to the problem. Presented here are methods which take advantage of the structure of speech and the phase properties of the Fourier transform. They are based on the cross-spectral methods of the 80’s, but have the advantage that these newer methods provide good accuracy and resolution for nonstationary signals such as speech. In addition, they provide a simple method for taking advantage of signal structure, such as the harmonic properties of speech, which results from the quasi-periodic pitch excitation. Specific problems addressed are accurate pitch and formant estimation, and problems such as blind recovery of carrier frequencies for single side band AM radio transmissions.
Applications of time-frequency analysis in musical acoustics
Authors: Wakefield Gregory H. , Mellody Maureen , Guevara Rowena , Pielemeier William
Published: July 2002

The modal distribution (MD) is a member of Cohen’s class of time-frequency distributions that is designed specifically for signals that are well-modeled as the sum of time-varying partials, such as those generated by many musical instruments [W. Pielemeier and G. H. Wakefield, J. Acoust. Soc. Am. 99, 2382–2396 (1996)]. When combined with local operators on the time-frequency surface, MD analysis provides substantial improvement over techniques based on the spectrogram with respect to simultaneously resolving variations in amplitude and frequency. Furthermore, the analysis degrades gracefully as the acoustic signal varies from the specified model and, in several cases, can be extended to handle a broader class of signals. Examples drawn from violin vibrato, singing, and the piano are used to illustrate MD analysis and its extensions. Issues of system identification, time-varying signal models, and musical synthesis are also discussed on the basis of these examples. [Research supported by grants from the Ford Motor Company, the Office of Naval Research, the National Science Foundation, and the Office of the Vice President for Research at the University of Michigan.]
Characterization of densities by moments
Authors: Cohen Leon
Published: July 2002

For two-dimensional classical densities it is very often the case that the general properties of a density can be characterized by low-order joint moments and conditional moments. The advantage of this is that moments and conditional moments are constants and one-dimensional functions, respectively, and hence can be more effectively used for characterization, classification, and detection than the full density. In the time-frequency case unique problems arise. First, the definition of conditional moments is problematic and has not been fully investigated. Second, since a time-frequency density may go negative the methods of probability theory may not be taken over directly. We investigate these issues and show that time-frequency conditional moments can be defined in such a way that they appropriately characterize the general features of a time-frequency density. [Work supported by ONR.]
Source level and Urick
Authors: Barger James E.
Published: July 2002

Source level (SL) is the first term in Bob Urick’s sonar equation, and it represents the root-mean-square pressure of sound radiated at the target, in decibels. The fundamental measure of source level is the signal-energy level (SEL) represented by the time integral of sound pressure squared, to which the detection index is proportional, in decibels. Despite using a form of sonar equation more natural for long-pulse transducers than for impulsive ones, he only described explosives in detail in his chapter on generation of underwater sound. When ‘‘Principles of Underwater Sound for Engineers’’ was published, there was a tendency to use impulsive sound sources to study sound interactions with the sea and to use narrow-band long-pulse transducers in sonar systems. The diminution of this tendency has been a very important development since Bob’s book was written, and it has occurred because of improvements in both kinds of transduction. Transducer bandwidth has been increased, both by materials with larger electromechanical coupling coefficients and by innovative designs. These include ‘‘hybrid’’ transducers that combine magnetostrictive and electrostrictive actuators and projector arrays designed to have no mechanical reactance. Improved impulsive sound sources such as air guns, sparkers, and explosive arrays now find sonar use.
Properties of transducer arrays: Directivity index (Urick, 1967)
Authors: Baggeroer Arthur B.
Published: July 2002

The chapter, ‘‘Properties of Transducer Arrays: Directivity Index,’’ in Urick’s text includes not only the directivity index (DI) of an array, but also many of the important metrics of spatial performance which remain important in assessing the performance of a sonar system. Beampatterns, tapers and sidelobes, signal gain, noise gain and even superdirectivity are all included. The DI metric in the sonar equation indicates gain against 3-D isotropic noise; alternatively, it is used to convert a beam noise level to power per steradian. While easy to compute and appropriate when a field is diffuse, the DI is not a good metric for spatially discrete noise such as shipping which can often dominate a noise field. Recently, the signal and noise gain metrics are used more often. Signal gain is an issue as sonar systems use very large apertures; noise gain is also an issue when the directionality of the noise fields is exploited. Certainly, the most significant evolution in spatial processing not included in Urick’s chapter was the use of adaptive processing which has been enabled by the availability of high-speed DSP for real time processing. The presentation will review Urick’s important contributions to describing the performance of arrays and how they have impacted sonars.
Techniques for passive detection and localization of marine mammals using wide aperture arrays
Authors: Bondaryk Joseph E. , D’Amico Angela , Portunato Nicola
Published: July 2002

SACLANTCEN is sponsoring a program entitled Sound Oceanography and Living Marine Resources Program, whose objective is to demonstrate dual use technology for passive detection and localization of marine mammals, which will assist in the implementation of acoustic risk mitigation policies when using high-power acoustic sources. A sea trial was conducted in August 1999 to evaluate marine mammal detection and localization techniques using a number of advanced passive arrays. Passive, bearing-only data from marine mammal vocalizations received on a towed horizontal line array and target motion analysis are used to localize whale position. The multipath arrival structure of received signals and a ray trace model are used to determine whale range and depth over time. Data from several stations, executed using three deployed vertical line arrays in the vicinity of diving whales, and triangulation of arrivals are used to track whale location in the horizontal plane, while beamforming of the vertical array data is used to track whale depth. Evaluation of these data and techniques will be used to formulate passive procedures for determining the presence of marine mammals prior to activation of high-power acoustic sources.
Bacterial stress response due to acoustic cavitation
Authors: Willman Ann M. , Vollmer Amy C. , Everbach E. Carr
Published: July 2002

E. coli bacteria that have been genetically engineered to emit visible light when they are stressed provide a means to study the mutual interactions of ultrasound, bubbles, and bacterial cells [Vollmer et al., Appl. Environ. Microbiol. 64, 3927–3931 (1998)]. Stresses such as protein damage, DNA damage, oxidative stress, and membrane perturbation produce differential light output in different strains of bacteria exposed to similar acoustic cavitation fields. The relative severity of each of these stressors, as determined by the luminosity per surviving cell, suggests the relative importance of each damage mechanism. Besides giving insight into cavitational mechanisms, the results suggest the parameters most useful for acoustic purification of water.
Vibration measurements of radio frequency micro-scale acoustic devices
Authors: Morse Scot F. , Vignola Joseph F. , Houston Brian H. , McGill Andrew R. , Greenblatt Jeremy , Chung Russell
Published: July 2002

Current micromachining and IC manufacturing technology has enabled the development of a wide range of acoustic sensors and devices operating at frequencies up to several GHz. Accurate measurements of the vibrational behavior of these devices is often complicated by their small size, intricate geometry and high operating frequencies. To address these issues a measurement system based on a fiber delivered heterodyne laser interferometer has been developed to perform spatially dense measurements of the surface displacement at high frequencies. With this system, noncontact displacement measurements can be made with sub-angstrom sensitivity for a spot several micrometers in diameter. Evaluation of the system is made with 2-D scans of the normal surface displacement of a 110-MHz delay line surface acoustic wave (SAW) chemical vapor sensor. Measured displacement levels of the uncoated quartz substrate for this device are typically less than 1 nm for acoustic wavelengths of 29 mum. Limitations of this method are discussed, including the effect of spatial filtering brought about by the finite optical spot size. [Work sponsored by the Office of Naval Research.] a)National Research Council-NRL Research Associate. b)Also with SFA, Inc., Landover, MD 20785.
Speech production factors in children using cochlear implants
Authors: Tobey Emily
Published: July 2002

This presentation will summarize speech intelligibility, sound development, and durational characteristics of 92 children who use multichannel cochlear implants. All children had at least 5 years experience with the device and whose chronological age was 8 or 9 years. Half of the children used auditory-oral modes of communication and the other half used total communication. Speech intelligibility was assessed using 36 sentences of 3, 5, and 7 syllables in length [McGarr (1981)]. Samples were recorded, digitized, edited, randomized, and played to listeners (72 listeners per child). Samples also were phonetically transcribed by three independent raters. In addition, recordings were made of CV syllables in isolation or as the final syllable of a two-syllable word. Data indicated speech intelligibility was significantly higher in the children with auditory-oral modes of communication (p<0.01). Sound development also was significantly higher in children with auditory-oral modes of communication (p<0.01); however, the pattern of sound development was similar in the two groups. Children with less intelligible speech also experienced difficulty in producing CV syllabes in final syllables as indiced by their acoustic measures. Syllables displayed inappropriate durations and formant values approximating schwas. [Work suppported by NIH.]
A study of an impedance reflection model of sound fields in rooms using the Bergeron method
Authors: Shimoda Hidemaro
Published: July 2002

In the Bergeron method [Shimoda et al., Trans. Inst. Electron. Commun. Eng. Jpn., Part A 72, 1–11 (1989); English transl., 1989 Electron. Commun. Jpn., Vol. 72; Scripta Technica, Inc. (Wiley, New York, 1990)], sound reflection surfaces in rooms are modeled by the simple resistances corresponding to the rigid walls. And the low-frequency responses for a middle scale of auditorium are agreed preferably with the real fields [K. Nakagawa and H. Shimoda, ASVA 97]. However, for big absorption acoustic models such as recording studios, or mixing rooms, the surfaces in rooms must be modeled by the impedance reflections. In this paper, the basic treatments for the impedance reflection models in the Bergeron method are investigated, and the wideband time-stretched pulses are used to simulate one-dimensional sound fields. The feasibility of numerical simulations using the Bergeron method are confirmed by supposing a simple surface impedance reflection model.
Behavioral reactions of peregrine falcons (Falco peregrinus) to military jet overflights
Authors: Nordmeyer Dana L. , Roby Daniel D.
Published: July 2002

Behavioral reactions of peregrine falcons (Falco peregrinus) to military jet overflights were observed at 12 nests along the Tanana River, Alaska during each of the 1995–1997 breeding seasons. Low-altitude flights were conducted over a sample of nest sites under observation (‘‘experimental’’ nests), while other nests were not intentionally overflown (‘‘reference’’). Productivity did not differ between experimental and reference nests and was within the normal range for Interior Alaska. Productivity also did not differ between nests exposed to many close overflights (≤1000-m slant distance from the nest) versus those exposed to few, nor between nests exposed to high levels of overflight noise versus those exposed to low levels. Adult peregrine falcons exhibited little or no overt behavioral reaction to the majority (78%) of observed close military jet overflights. Only 5.5% of reactions were classified as intense or flight. There were, however, significant differences among individual adult peregrines in the intensity of reaction to close overflights, after controlling for gender and slant distance. The average reactivity of individuals or pairs was inversely related to productivity. These results suggest that the sensitivity of breeding peregrine falcons to low-altitude jet overflights is a better indicator of subsequent productivity than actual dose of overflights.
Hot topics in animal bioacoustics
Authors: Ridgway Sam
Published: July 2002

Discoveries in the amphibian flipper of the animal bioacoustics community include Alejandro Purgue’s discovery that North American Bullfrogs emit 90% of the power of their calls from their eardrums, and only 10% from their vocal sacs has perhaps been the most original and surprising result of this decade. Peter Narins, Ted Lewis, and Blinda McClelland have shown that males of the endemic Madagascar tree frog have hyperextended their vocal repertoire to least 28 different calls. From the bat wing, von Helversen and von Helversen report that a bat-pollinated vine directs echolocating pollinators to its flowers by means of an acoustic guide. Valentine and Moss report on specializations in the bat superior colliculus for acoustic orientation by sonar. Three groups have new findings regarding temporary threshold shift (TTS) in marine mammals. Schusterman and Kastak observed a very small shift after broadband noise of over 20-min duration in a sea lion. Au and Nachtigall observed a 12-dB shift using one-octave noise of 179 dB, that is, 1 μPa in a bottlenose dolphin. Carder, Finneran, Ridgway, Schlundt and co-workers have produced TTS of 6 to 18 dB using 1-s tones of 192 to 202 dB in white whales and dolphins.
Sense and nonsense concerning design and engineering of the theaters of classical antiquity and the writings of M. Vitruvius Pollio on the subject
Authors: Izenour George C.
Published: July 2002

This paper is a concentrated encapsulation of the theater architecture of classical antiquity utilizing paired slides of theater restorations in plan and perspective section accompanied by selected photographs of archeological sites. All of this is occasioned by four decades of the author’s travels, researches, writings, ruminations, and conclusions concerning the theaters of ancient Greece and Rome. Considered in the abstract and irrespective of historical epoch, the functional purpose underlying all theater architecture is to provide the physical means by which an audience, preferably comfortably seated, is enabled to both see and hear a staged performance. It is the purpose of this paper to equate the archeologically revealed ‘‘SENSE’’ with the romantically derived fictious ‘‘NONSENSE’’ of both the outdoor and the roofed theaters of classical antiquity. A contemporary perspective concerning the ‘‘SENSE’’ and the ‘‘NONSENSE’’ of the writings of M. Vitruvius Pollio on theater architecture is also provided. O tempora O mores.
A study of the effect of ultrasound on mandibular osteodistraction
Authors: El-Bialy Tarek H. A. , Royston Thomas J. , Magin Richard L. , Evans Carlotta A.
Published: July 2002

Previous studies have shown that low-frequency ultrasound can enhance bone fracture healing. Other craniofacial research studies have indicated that distraction osteogenesis (bone lengthening) can be performed with some degree of success on the mandible. However, a complication typically reported is the bending of the anterior portions of the osteotomized mandibles which is believed to be caused by the stretching of the circumoral muscles on the newly formed bone callus. It is hypothesized that application of a low-frequency ultrasound treatment to osteotomized mandibles may enhance bone formation and minimize the healing period, thus minimizing the stretching of newly formed callus. Preliminary results are reported here which test this hypothesis on rabbit models. The ultrasound treatment regimen and the acoustic techniques used for assessing healing are discussed.
Ultrasonics for process monitoring and control
Authors: Bond Leonard , Greenwood Margaret , Bamberger Judith
Published: July 2002

Ultrasonic waves are well suited for use in measurements that characterize multiphase fluids and flows. The waves can interrogate fluids and dense optically opaque suspensions. Transducers can give signals that penetrate vessels. Such transducers, together with supporting instrumentation, can provide on-line real-time measurements for use in process monitoring and control. Staff at the Pacific Northwest National Laboratory have developed a family of devices that measure fluid and slurry density, viscosity, flow rheology, particle size distribution, concentration, and velocity profiles. The transducers have been deployed on model systems to provide data that can be integrated to provide a more complete characterization of a process streams, including to detect time-dependent changing interfaces caused by fouling or phase changes, to track process conditions during mixing, sedimentation, stratification, and slurry transport. A summary of the fundamental physical acoustics for wave-process stream interactions will be provided. Examples that illustrate the capabilities of each type of measurement applied to slurry systems at Hanford site and for wood pulp process streams will be presented. The potential for enhanced process monitoring and control will be illustrated using wood pulp data, where it is required to measure the pulp consistency and degree of refining.
Sonar dome deflection measurements on the USS Radford
Authors: Covey Joel F. , Corsaro Robert D. , Weaver Diane B. , Walker Jonathan B.
Published: July 2002

Sonar dome deflection measurements were performed on the new monolithic sonar dome of the USS Radford in Oct.–Dec. 1997. Over 700 Mbytes of raw data from 22 environmental sensors and 128 displacement sensors were obtained. The at-sea data acquisition was highly successful with data collected over sea states 1 through 4, and for numerous ship speeds up to 31 knots. Analysis of this data has provided a more complete characterization of previously measured sonar dome deformations. Many new conclusions and observations on sonar dome behavior have been observed and correlated with ship motions.
The influence of later arriving sounds on the ability of listeners to judge the lateral position of a source
Authors: Dye Raymond H.
Published: July 2002

This investigation focuses on the effect that later sounds have on the ability of humans to report the spatial location of earlier sounds. Two dichotic pulses were presented (via headphones), separated by an echo delay between 4 and 64 ms. Listeners were asked to judge whether the first click appeared to the left or right of the intracranial midline. The interaural delay of each pulse was independently selected from a Gaussian distribution (μ, σ=0, 100 μs). The level of the echo relative to the source was 0, −6, −12, −18, −24, −30, or −36 dB. The effect of the echo was determined by measuring proportion correct and by deriving a normalized source weight. For echo delays of 16, 32, and 64 ms, the source and echo click were weighted equally when presented at the same level, and weights barely changed until the echo was attenuated by 18 dB. As the level of the second click was further reduced, the source weight approached 1.0 and the percentage correct approached that obtained in the ‘‘no echo’’ condition. For shorter echo delays, source weight and proportion correct increased more quickly as the echo was attenuated. [Work supported by NIDCD & AFOSR.]
On the mechanism of lowering the voice fundamental frequency in the production of tones of Standard Chinese
Authors: Fujisaki Hiroya
Published: July 2002

While it is well known that the cricothyroid (CT) muscle is mainly responsible for lowering the voice fundamental frequency (F0) in many languages, the mechanism for F0 lowering in languages such as Standard Chinese (SC) has not been elucidated. Although several studies have shown that the sternohyoid (SH) muscle activity is strongly correlated with F0 lowering in SC, the mechanism itself is not clear since SH is not directly attached to the thyroid cartilage, whose movement is essential in changing the length and tension of the vocal chord. On the basis of an earlier finding on the production of Thai tones [D. Erickson, Annual Bulletin No. 27, RILP, Univ. Tokyo, pp. 135–149 (1993)], the present author has suggested the active role of the thyrohyoid (TH) muscle in F0 lowering in languages such as SC and Swedish [H. Fujisaki, Proc. XXIII World Congress of the International Association of Logopedics and Phoniatrics, pp. 156–159 (1995)]. The present study shows the detailed mechanism for F0 lowering involving both TH and SH in the production of the second, third, and fourth tones of SC based on new electromyographic observations.