bluuebunny/crossref_metadata_2025 huggingface dataset:
A review and critique of theories for piezoelectric laminates
Authors: Senthil V. G. , Varadan Vasundara V. , Varadan Vijay K.
Published: July 2002

This paper presents a three-dimensional (3-D) complete field solution for active laminates based on a modal, Fourier series solution approach that is used to compute all the through thickness electromechanical fields near the dominant resonance frequency of a beam plate with two piezoelectric (sensor and actuator) and one structural layers. Then a detailed review of the extant laminate models used for piezoelectric laminates emphasizing the underlying assumptions in each case is presented. The nonzero, through thickness field components are computed under these assumptions. The results of the 3-D model and FSDT model are compared for two aspect ratios (AR thickness to width of layers). An AR of 20 is at the limit of FSDT and an AR of 50 well within the assumptions of FSDT. It is concluded that for moderate aspect ratios, several of the approximations of FSDT are questionable at resonance frequencies, resulting in large errors in the estimation of the elastic and electric field components.
Examining processor and stimulus list differences in word recognition by children using a cochlear implant
Authors: Frisch Stefan , Meyer Ted A. , Pisoni David B.
Published: July 2002

Boothroyd and Nittrouer [J. Acoust. Soc. Am. 84, 101–114 (1988) J. Acoust. Soc. Am. 87, 2705–2715 (1990)] and Rabinowitz et al. [J. Acoust. Soc. Am. 92, 1869–1881 (1992)] have demonstrated a power-law relationship between the accuracy in phoneme recognition and the accuracy in word recognition by normal hearing adults, older adults, children, and adults using cochlear implants. The power-law relationship provides a simple mathematical model of context effects on speech perception. An analysis of spoken word recognition performance by children using cochlear implants reveals an analogous power-law relationship between phoneme and word recognition. Further, comparison between groups using two different speech processors (SPEAK and MPEAK) shows that, while overall performance is affected by the processor, the power-law relationship is unaffected. By contrast, comparison between different stimulus lists finds the power-law relationship is affected by the phonotactic structure of the 20 lexical items used and their familiarity to the listener. [Work supported by NIH, AAO-HNS.]
Contrast effects with sinewave analog anchors
Authors: Fox Robert A. , England Sarah
Published: July 2002

An area of interest for several decades has been the effect of the immediate phonetic context on vowel perception—especially in terms of the phonetic contrast effect. One of the questions regarding this easily replicated effect is whether it is a phonetic-level effect or an acoustic-level effect. The current experiment was designed to determine whether the same contrast effect on the identification of a /i/–/I/ synthetic vowel continuum would be obtained with synthetic vowel (SV) anchors (representing one of the two endpoints) and with sinewave analog (SA) vowels (substituting tone glides for vowel formants). The stimuli included a nine-point /i/–/I/ SV continuum (produced with the Klatt program) and a correlated SA continuum. There were three basic anchoring conditions: anchoring (1) with the SV endpoints, (2) with the SA endpoints (subjects identified these tokens as tones), and (3) with the SA endpoints after subjects had been trained to identify them as vowels. Results showed a significant anchor effect with SV anchors (as expected) and no anchor effects with the SA anchor prior to training. Subjects did show a significant anchoring effect with the SA anchors after training, but the effect was significantly smaller than with SV anchors.
Further development of time delay spectrometry
Authors: Finch Bradley , Cook Gareth , Zaknich Anthony
Published: July 2002

The accuracy of conventional time delay spectrometry (TDS) measurements are limited by constraints on signal parameters. These constraints ultimately limit the resolution with which the frequency response can be measured. Poletti, Cook, and others have shown that more exact measurements, without these constraints, are possible. These theories require that the system response to the full complex chirp be known. This is usually done by exciting the system with two separate orthogonal sweep signals. In this paper, this theory is developed in a manner similar to that done by Vanderkooy for the conventional TDS measurement, to show that the more exact system response can be deduced from a single linear sweep. The new development is supported by experimental results comparing the measured system response of a series resonant circuit against the conventional TDS results originally reported by Vanderkooy. This method provides practitioners more convenience in making exact TDS measurements, and allows for further exploration of the application of this technique in time varying environments.
Predicting the effects of sound exposure on fish, marine mammals, and human beings
Authors: David Antoine , Ward Peter , Heathershaw Tony , Varley Peter
Published: July 2002

Fish and marine mammals are sensitive to sound and may be affected by sound energy from a wide range of sources. Current concern is focused on anthropogenic sound and in particular sound which emanates from active sonar devices. This may range from broadband short-duration events to narrow-band signals with long-time exposure. Frequencies may extend from a few hundred Hz to a few hundred kHz. In order to be able to predict the effect of sound on fish, marine mammals, and human beings, it is first of all necessary to predict the propagation of sound through the ocean environment and then to estimate the effect of a received sound pressure level on an environmental receptor. To achieve this latter objective, a generic threshold of hearing model has been developed which is suitable for use with sonars of arbitary frequency and duty cycle. The model, which is described in this paper, relates the effects of sound in both the frequency and time domains. This enables the onset of TTS, PTS, and an equivalent damage risk criteria to be predicted as a function of the distance between an environmental receptor and a sound source.
Good classroom acoustics are a good investment for America
Authors: Lubman David , Sutherland Louis C.
Published: July 2002

Buzz Towne’s idealism sparked ASA’s current activities to improve classroom acoustics, including ANSI S12 WG43’s activity to produce an American standard for classroom acoustics. But idealism alone may not suffice to realize the reforms Buzz sought. It will help if advocates can show that good classroom acoustics are a good investment for community and nation. Absent were the resources necessary for serious economic cost-benefit studies, some very informal, ‘‘back-of-the-envelope’’ engineering estimates were made by acousticians, audiologists, and material vendors. All assume 20 year life cycles for new and renovated classrooms. In one scenario, costs for quiet HVAC and sound absorbing ceilings are shown to be a small fraction of costs for ordinary school construction yielding substandard acoustics. In another scenario, costs for quiet classroom HVAC are shown to be small compared to annual operating costs per student. A third scenario shows that a modest but plausible assumed increase in average lifetime earnings generously will repay the initial costs for good acoustics. These scenarios do not consider the economic costs of bad acoustics, including high dropout rates, truancy, juvenile crime, and teacher burnout. The authors hope to inspire others to more fully study the economic, social, and educational benefits of good acoustics.
Optimal acoustic conditions in classrooms
Authors: Siebein Gary W. , Gold Martin A. , Ermann Michael G. , Siebein Kerry N. , Siebein Glenn W.
Published: July 2002

Computer models of eight classrooms were constructed with varying combinations of absorbent materials on the surfaces of the rooms using the CATT 7.0 computer program. The amount, location and cost of finish materials and the noise levels produced by the air-conditioning system were varied in the models. RASTI values were calculated for six seats in each room. By determining conditions that result in maximum RASTI values, maximum speech intelligibility conditions were obtained. Background noise levels dominated the RASTI values at levels of NC 40 and higher regardless of room finishes. At RASTI values of NC 35 and less, once an amount of absorbent material equal in area to the floor was present, only small changes in RASTI values were observed whether the material was located on the ceiling or the upper parts of the walls or a combination of both. The cost of material and locations of typical furnishings were also considered in the process.
The passion behind changing the sound of education
Authors: Anderson Karen L.
Published: July 2002

Educational audiologists have been fighting the war of poor classroom acoustics for over 20 years. Research has amassed in the audiology literature evidencing the negative effects that inadequate acoustic treatment in classrooms have on student learning, behavior and attention. Buzz Towne dared to cross professional demarcations and take to heart the lessons of the audiology research. This presentation is made as a tribute to Buzz, by the audiologist who spent hours with him, having lively discussions as two bodies of research were compared. Buzz Towne’s interest in the plight of children forced to learn in inadequate learning spaces turned into a passion. The Sound & Vibration, January 1997 article, ‘‘The Changing Sound of Education,’’ was born of this meeting between acoustics and audiology. This passion demanded that the sound of learning was harming our children and our country’s future. It forced the realization that education has changed and acoustical designs of 50 years ago are preventing today’s children from achieving all that they need to learn for tomorrow. Buzz was instrumental in starting the wave of interest in classroom acoustics that has awakened acousticians across the country that will bear fruit in improved learning of millions of children.
Structual variables and their relationship to background noise levels and reverberation times in unoccupied classrooms
Authors: Knecht Heather A. , Whitelaw Gail M. , Feth Lawrence L. , Nelson Peggy B.
Published: July 2002

The classroom environment is often filled with deterrents that hamper a child’s ability to listen and learn. These deterrents include background noise and reverberation leading to poor signal-to-noise ratios that can interfere with learning. By examining the acoustical conditions for speech communication in the classroom, it is evident that the acoustical environment in classrooms can affect the achievement and educational performance of children with sensorineural hearing loss (SNHL), children with normal-hearing sensitivity who have other auditory learning difficulties, as well as elementary school children with no verbal or hearing disabilities. The purpose of this study was to measure reverberation and background noise levels in 32 different unoccupied elementary classrooms in eight different public school buildings in Central Ohio. These measurements were then compared to the external and internal criteria variables developed [Crandell et al., ‘‘Sound-Field FM amplification theory and practical applications’’ (1995)] to determine if a relationship existed between classroom background noise levels and reverberation and the building criteria variables. Data were analyzed for overall noise level, reverberation time, and correlation between the reverberation time and internal/external criteria variables.
A mathematical model of singers’ vibrato based on waveform analysis
Authors: Diaz Jose A. , Rothman Howard B. , Arroyo A. Antonio
Published: July 2002

There is controversy regarding the best model to synthesize vibrato. Some authors include random components in their models while others suggest a deterministic model. Also, the vibrato waveform has not been studied in detail, that is, no measures have been made as to symmetry of the waveform, and parameters different from wave frequency and amplitude have not been studied. Therefore, research was undertaken to thoroughly analyze the vibrato waveform from selected singers in order to obtain a model based on the vibrato parameters. Seven premier-level singers were selected and three samples per singer were used. These samples were analyzed through the MMSV (Mathematical Model of Singers’ Vibrato) software, which was specifically designed for vibrato analysis. The results obtained for all the samples were analyzed and compared, and a model fitting all of them was proposed. This model was compared against a sinusoidal model and the real wave for two different samples by the use of an error measure and visually, and it was verified that the model reproduced the variations of the real vibrato wave and significantly reduced the error measure of the sinusoidal model. The results show that a deterministic model fits all the samples under study.
Visual feedback in teaching singing using speech technology
Authors: Thorpe C. William , Callaghan Jean , van Doorn Jan
Published: July 2002

Visual feedback of voice parameters has been shown to be useful in singing training, but most current systems are designed for speech applications. Extraction of parameters such as the fundamental (F0) and formant frequencies can be problematic in singing because of the overlap between F0 and the formants over much of the pitch range. This has limited the application of visual feedback tools in the teaching of singing. This experiment aimed to obtain empirical data on the boundaries within which standard speech-oriented visual feedback systems can be usefully utilized for teaching singing. Four singing teachers learned to operate a simplified set of visual feedback modes on the Computer Speech Laboratory (Kay Elemetics), and then used the system in several lessons, after which they were interviewed about the utility of the system. They found that feedback of F0 and vowel formants were the most useful modes, in spite of limitations in the precision of pitch feedback and the reliability of formant extraction at high F0. The results suggest that current speech-based visual feedback systems can be usefully integrated into singing pedagogy, but that even greater benefits would accrue if more precise F0 and reliable formant-identification algorithms were developed.
Melody-tone relation in Cantonese songs
Authors: Wong Patrick C. M. , Diehl Randy L.
Published: July 2002

How is fundamental frequency (F0) being used to signal phonemic tones when they occur in songs? In an examination of Cantonese songs, it was found that songwriters abandon the ‘‘absolute’’ pitch intervals of tones in speech and use ‘‘relative’’ intervals instead in song writing. For example, a midtone that is regularly 12% higher than a low tone in speech can be realigned as any higher F0 (but never a lower F0) in songs. This analysis was confirmed by a perceptual experiment. Listeners were asked to listen to six different melodies accompanied by a semantically neutral lyric: /ha6 yat1 go3 zi3 hai6 si3/ ‘‘The next word is to try,’’ and were asked to identify the last word. (The number signals tone; ‘‘3’’ is a midtone and ‘‘6’’ is a low tone.) When the last pitch in the melody was higher than the note before, the last word (/si3/) was identified as either a high tone or a midtone (because they are higher tones than the low tone associating /hai6/). When it was lower in pitch, the last word was identified as a low tone. [Work supported by NIDCD.]
Studies of accordion reed vibrations—Applications in sound synthesis
Authors: Caussé René , Misdariis Nicolas , Ricot Denis
Published: July 2002

The accordion is a free-reed instrument. The two identical reeds associated with one note are driven separately by the airflow created by the inward and outward movements of the bellows. In this present study, attention is focused on understanding the aerodynamic phenomena involved in reed vibration. The acoustical model is deduced from the variation of the flow rate through the slot in the reed plate. A variety of laboratory measurements and observations on different accordion reeds have been made with different blowing pressures. Among them: near-field sound pressure (microphones above and under the reed); displacement and velocity of the reed (capacitive sensor and laser vibrometer system); reed profile, magnified stroboscopic images, flow visualization; etc. From these experimental results, we have extracted the most important phenomena involved, which are to be implemented in a physical model accurate enough to describe the behavior of the reed and to reproduce its characteristic sound. This physical model must be as simple as possible to be computationally efficient and usable in sound synthesis. For example, at IRCAM, it is possible to program the accordion model in Modalys, a synthesizer language based on modal representation formalism. Similarities and differences between simulated and real sounds will be discussed.
Harmonic generation by Rayleigh–Lamb waves in isotropic elastic plates
Authors: de Lima W. J. N. , Hamilton M. F.
Published: July 2002

Harmonic generation by Rayleigh–Lamb waves of finite amplitude in homogeneous, isotropic, stress-free elastic plates is investigated theoretically. A bifrequency primary wave field is considered, in which the two waves propagate in single yet arbitrary Rayleigh–Lamb modes. Solutions for the second-harmonic and difference-frequency components are obtained via modal decomposition and use of reciprocity relations. Two conditions are required for generation and resonant amplification of these spectral components, power flow, and phase matching. Second-harmonic generation is considered first. Although phase matching is possible between a primary wave in the first symmetric mode and its second harmonic in the second asymmetric mode, the power flow is found to be zero. However, with one primary wave in each of the first symmetric and asymmetric modes, both phase matching and power flow may be achieved with the difference-frequency wave generated in the first asymmetric mode. In particular, resonant parametric amplification of the difference-frequency wave can be achieved under conditions where dispersion prevents efficient coupling from occurring between the primary waves and other frequency components. Explicit analytic solutions are presented and discussed. [Work supported by the Brazilian Ministry of Science and Technology, and the National Science Foundation.]
Theoretical analysis of free-shape oscillations of surfactant-bearing drops
Authors: Chen Xiaohui , Apfel Robert E.
Published: July 2002

A theoretical analysis is presented for the free-shape oscillations of surfactant-bearing drops suspended in air using the method of spherical harmonic expansions. Two extreme types of surfactant mass transfer between the bulk and the surface of drops are considered: (1) no surfactant transport as the drop oscillates; and (2) the surfactant transport is so fast that the surface surfactant concentration remains constant and homogeneous. It is found that the shear viscosity of bulk phase, surface elasticity, surface shear viscosity and surface dilatational viscosity have the same order of influence on the free-damping constant when the surface shear viscosity is smaller than a certain value. Otherwise, the free-damping constant is determined by the surface shear viscosity, and the influence of the surface dilatational viscosity, the surface elasticity, and the shear viscosity of the bulk phase on the drop oscillation is negligible.
Comparing the vibrational behavior of wood and aluminum baseball bats
Authors: Russell Daniel A.
Published: July 2002

Experimental modal analysis was performed on a variety of wood and aluminum baseball bats to study the differences and similarities in vibrational behavior. Wood bats were found to exhibit split pairs of vibrational modes whose frequencies depend on whether the plane of vibration is along or across the grain. The frequency separation for these duplicate modes varies considerably from bat to bat and appears to be dependent on the quality of wood. Data will be presented for bats made from ash, maple, an ash–hickory–maple combination, and 6-ply laminated ash. Aluminum bats exhibit a single set of bending modes, with similar shapes but wider frequency spacing than wood bats. However, aluminum bats also vibrate with several cylindrical bell-type modes, the lowest of which is found to be responsible for the loud ‘‘ping’’ produced when a metal bat strikes a ball. Aluminum bats also allow greater modifications for improved bat performance. An example of an aluminum bat with a dynamic absorber will be compared to other metal and wood bats.
Power variances in a reverberant elastic system
Authors: Weaver Richard L. , Lobkis Oleg , Rozhkov Igor
Published: July 2002

Frequency-dependent fluctuations in the power transmissibility of a reverberant elastic body are measured and compared with theoretical estimates. Wideband (0.1–2 MHz) transient sources are applied to aluminum blocks of dimensions of the order of 3 cm (greater than typical wavelengths) and found to generate signals with durations of the order of 100 ms. At low frequencies the power spectra of these waveforms, found by FFT, show the usual distinct resonance peaks that allow unambiguous mode counting. At higher frequencies, where modal overlap is significant, mode counting is more difficult. Nevertheless, modal density is, in principle, recoverable by analysis of the variance of the power spectra. An improved theory for the relative variance is presented, which includes the effects of variations in modal widths and includes the effects of spectral rigidity. The theory assumes that modal amplitudes are Gaussian random numbers, as is predicted by random matrix theory. The method consistently overestimates modal densities, by about 50%. After elimination of other causes, the discrepancy is attributed to the assumption on modal amplitude statistics.
Scaling of time-reversing array performance in the presence of ambient noise
Authors: Khosla Sunny R. , Dowling David R.
Published: July 2002

Time-reversing arrays (TRA) have the capability to exploit unknown multipath environments to retrofocus acoustic waves, in both time and space, back to their original source location. Although TRA retrofocusing may be robust, it is degraded by ambient noise. The noise received by the array and the noise existing locally in the focal region cause a reduction in the focal-point signal-to-noise ratio and simultaneous waste of the useful power output of the array. A vertical TRA operating in simple environments containing an isotropic noise field is considered. A focal probability criteria is developed to quantify the retrofocusing performance of the TRA. This approach leads to a simple scaling law that incorporates the ambient noise level, the original source level, the array element level, the array element number, and the acoustic environment parameters. Results for free space and a shallow-water sound channel will be presented. Operating regimes strongly influenced by original source level and TRA element power level are clearly defined by this effort. [Work sponsored by the Office of Naval Research, Ocean Acoustics.]
Updated technology baseline in underwater acoustic modeling, simulation, and analysis
Authors: Etter Paul C.
Published: July 2002

A comprehensive review of international developments in underwater acoustic modeling is used to construct an updated technology baseline containing 106 propagation models, 16 noise models, 17 reverberation models, and 25 sonar performance models. This updated technology baseline represents a 30% increase over the previous baseline published in 1996 [P. C. Etter, Underwater Acoustic Modeling: Principles, Techniques and Applications, 2nd ed. (E & FN Spon, London, 1996)]. When executed in higher-level simulations, these models can generate predictive and diagnostic outputs that are useful to acoustical oceanographers or sonar technologists in the analysis of complex systems operating in the undersea environment. Recent modeling developments described in the technical literature suggest two major areas of application: low-frequency, inverse acoustics in deep water; and high-frequency, bottom-interacting acoustics in coastal regions. Rapid changes in global geopolitics have opened new avenues for collaboration, thereby facilitating the transfer of modeling and simulation technologies among members of the international community. This accelerated technology transfer has created new imperatives for international standards in modeling and simulation architectures. National and international activities to promote interoperability among modeling and simulation efforts in government, industry, and academia will be reviewed. The implications of this updated baseline for technology planners will also be discussed.
Underwater acoustic vision
Authors: Keller K. , Mack S. , Lucas J. , Smith J.
Published: July 2002

An underwater acoustic camera has been developed to enable imaging of objects and scenes in environments, where water clarity makes optical methods redundant. The camera consisted of multiple transmitters, acoustic lens, and a 256-element receiver array. Continuous waves techniques were used, to provide range and intensity information which was then processed to produce three-dimensional images. The ranging technique uses a 1-MHz base frequency transmitted signal which was swept linearly according to a sawtooth pattern. The frequency difference between the transmitted and received signal frequencies, caused by the finite time of flight of the wave, determined the range of the target. Broadband transducers using PZT piezoelectric material were designed to provide acoustic illumination of the scene. The acoustic lens (either liquid or solid) focused the reflected rays onto the PZT/polymer receiver array. Images have been produced consisting of both single- and photomosaic frames. These showed the ability of the camera to produce images of objects of varying shapes and orientations, in environments where conventional optical systems were redundant (due to low visibility). A number of applications have been suggested for development based on the results produced, including subseabed mine detection and the docking of an underwater vehicle.
The Vern Knudsen Lecture: The compleat concert hall: A century of acoustics development and its lessons for the design of concert halls
Authors: Kirkegaard R. Lawrence
Published: July 2002

From the opening of Carnegie Hall just before the turn of the (20th) century, the art and science of concert hall design has advanced significantly...but that advance has been over many bumpy roads and with a number of detours along the way. As a profession we need to do all we can to assure that the halls we build in the future will serve as well in a hundred years as those that were built a century ago. In some instances that is a very tall challenge indeed. This provocative paper seeks to be visionary as well as retrospective, laudatory as well as critical. It is illustrated by experience and observation and delivered with respectfulness, but with enough challenge and irreverence to stimulate thoughtful and challenging discussion.
Concertinas: nuts, bolts, and music
Authors: Atlas Allan W.
Published: July 2002

Developed ca. 1830 by the physicist Sir Charles Wheatstone, the concertina has had a checkered career. This paper will discuss the various types of concertinas, outline the history of the instrument, discuss its construction, provide information on ‘‘how it works,’’ and intersperse live examples. Briefly, there are two national traditions: British and German, with various types of concertinas in each. In England, on which we shall concentrate, the concertina ‘‘fell’’ from its mid-19th-century success in both the concert hall and the drawing rooms of England’s socio-economic elite to become associated with folk music, the music hall, and the Salvation Army by the end of the century. After falling into almost total oblivion between the two world wars, the instrument has enjoyed an impressive comeback in the realm of folk music and has even aroused some interest (small, to be sure) in art–music circles. The instrument’s construction will be considered, as will the manner in which one concertina in particular works: the so-called ‘‘English,’’ on which live examples will be presented. The paper will conclude with a few words about the German bandoneon, its emigration to Argentina, and its evolution into the ‘‘signature’’ timbre of the tango orchestra.
Stochastic analysis of the internal wave effect on the SWARM observations
Authors: Mu Yongke , Badiey Mohsen
Published: July 2002

Wave propagation through random fluctuating media in time and space is a common theme in different fields. One such area, which provides a challenge, is shallow water acoustic wave propagation through internal waves. The effect of such propagation can range from an almost deterministic wave field to a completely stochastic one. The Shallow Water Acoustics in a Random Medium (SWARM) experiment has provided a comprehensive data set for studying the solitary internal wave effects on the broadband acoustic propagation. In order to understand the acoustic scattering observed in the SWARM data, we combined a nonlinear internal wave together with random variations of the environment, the correlation of which maps the internal wave regimes observed in the SWARM data, to the numerical simulations. The full wave parabolic equation (PE) model is adopted for simulating the broadband acoustic propagation. By varying the spatial and temporal statistics of the environment, the acoustic arrival signatures can be generated randomly with a given mean and standard deviation. Through this exercise we quantify the environmental statistics and its relationship to the acoustic waves by comparing the numerical and experimental data.
Technique for the generation and frequency compensation of bandlimited white noise and its application in studies of masked hearing thresholds
Authors: Finneran James J. , Carder Donald A. , Ridgway Sam H. , Schlundt Carolyn E.
Published: July 2002

Masking noise is often used in hearing tests to create a floor effect in the presence of ambient noise or to examine specific features of the auditory system (e.g., the critical bandwidth). One of the chief requirements of the masking noise is that it possess a flat frequency spectrum within some user-defined bandwidth. Generation of suitable masking noise is complicated by the frequency response of the sound projector, which may possess a frequency-dependent transmitting sensitivity and/or exhibit resonances within the desired frequency range. At low frequencies acoustic standing waves may also alter the noise frequency spectrum. To overcome these limitations, a technique has been developed to generate bandlimited noise whose frequency content is compensated in order to flatten peaks or valleys in the measured frequency spectrum. Compensation is performed by passing white noise through a digital filter whose coefficients are determined from previous measurements of the acoustic system frequency response. The system has been implemented using a personal computer with commercial hardware and custom software. The method has been used to quickly generate bandlimited Gaussian and uniform white noise for studies of masked underwater hearing thresholds in marine mammals. [Work supported by ONR and the NRC Research Associateship Program.]
Dialectal differences in diphthong perception
Authors: Makashay Matthew J.
Published: July 2002

This study attempts to determine if speech perception varies across dialects as production does. Synthetic stimuli based on one talker from Binghamton, NY (northern US) and one from Birmingham, AL (southern US) were presented to subjects from both regions. The stimuli were 18 vowel continua in CVC context. These 10-point continua had initial tokens containing nonhigh vowels, such as hot /hat/, with formant values and durations manipulated to result in final tokens containing diphthongs, such as hot /hɪt/. Other continua contained endpoints such as sad /sæd/ and side /saɪd/, or bought /bt/ and bout/baut/. The production of diphthongs differs between these dialects, varying from the Canadian raising of the North to the monophthongization of the South. The question to be resolved in this study is whether perception of diphthongs differs between the dialects. It was found in a direct boundary estimation task that southern subjects perceived southern tokens as diphthongs earlier in the continua than northern subjects did, while there was no significant difference between these groups for the northern diphthongs. [This material is based upon work supported under a National Science Foundation Graduate Fellowship.]
Developmental changes in perceptual weighting strategies for speech are contrast specific
Authors: Nittrouer Susan , Miller Marnie E.
Published: July 2002

In the labeling of /s/-/∫/, compelling evidence exists that children pay more attention to formant transitions and less attention to noise spectra than adults do. The purpose of this work was to examine whether such age-related differences extend to other contrasts, specifically /f/-/θ/. This contrast was chosen because compelling evidence also exists that adults pay more attention to formant transitions and less attention to noise spectra for /f/-/θ/ decisions than they do for /s/-/∫/ decisions, undoubtedly because /f/ and /θ/ noise spectra provide little information. Thus adults’ weighting strategies for this contrast should resemble those of children. To test that hypothesis, children (4, 6, and 8 years) and adults labeled fricative-vowel syllables consisting of natural /f/ and /θ/ noises combined with synthetic /ɑ/ and /u/ portions in which formant transitions varied from ones appropriate for /θ/ to ones appropriate for /f/. Results showed similar weighting strategies for adults and children for /ɑ/ syllables, but adults and 8-year-olds used the sparse information in the noise spectra for /u/ syllables to a surprising extent. Conclusions were that weighting strategies for some contrasts require no developmental adjustments, but that flexibility in perceptual weighting strategies is one general developmental change.
Nonlinear Doppler effect and its use for bubble flow velocity measurement
Authors: Didenkulov I. N. , Yoon S. W. , Sutin A. M. , Kim E. J.
Published: July 2002

The Doppler effect is a familiar phenomenon in linear acoustics. The nonlinear Doppler effect is also possible when a moving target exhibits nonlinear responses. In these cases Doppler frequency shifts arise at harmonics or combination frequencies in the scattered waves. For collinear geometry of primary beams, the nonlinear Doppler frequency shifts at the second harmonic and the combination frequencies are found to be the same as those for the linear scattering of those frequency components by the target. However, for highly, noncollinear primary beams, the difference frequency Doppler frequency shift can greatly exceed the linear one. This phenomenon is mainly studied in the present work. Experimental verification done with flowing bubbles in a tube shows good agreement with the theory. The suggested difference frequency Doppler technique can find applications in medical diagnostics of blood flow as well as in industries and in oceanology.
A model of facial biomechanics for speech production
Authors: Lucero Jorge C. , Munhall Kevin G.
Published: July 2002

Modeling the peripheral speech motor system can advance the understanding of speech motor control and audiovisual speech perception. A 3-D physical model of the human face is presented. The model represents the soft tissue biomechanics with a multilayer deformable mesh. The mesh is controlled by a set of modeled facial muscles which uses a standard Hill-type representation of muscle dynamics. In a test of the model, recorded intramuscular electromyography (EMG) was used to activate the modeled muscles and the kinematics of the mesh was compared with 3-D kinematics recorded with OPTOTRAK. Overall, there was a good match between the recorded data and the model’s movements. Animations of the model are provided as MPEG movies.
A vowel synthesizer based on formant sinusoids modulated by fundamental frequency
Authors: Hertrich Ingo , Ackermann Hermann
Published: July 2002

A vowel synthesis algorithm was developed resembling parallel formant synthesizers. However, the formants are computed as amplitude-and phase-modulated sinusoids instead of being represented by recursive filters or resonators. The fundamental frequency is imposed on the signal in the following way: Each pitch period exhibits an initial rise of a duration of π/2 of the first formant frequency; at the end of this ramp period all formants start as sinusoids at predefined phase angles and amplitudes, and successively undergo linear attenuation toward zero amplitude at the end of each pitch period. Adjacent pitch periods, thus, do not influence each other. In principle, the signals produced by this algorithm are similar to the output of parallel formant synthesizers [e.g., D. H. Klatt, J. Acoust. Soc. Am. 67, 971–995 (1980)]. However, by incremental sample-by-sample computation of the formants’ phase angles, formant frequencies are allowed to continuously change within single pitch periods. This new algorithm creates vowels as well as formant transitions signaling stop consonant–vowel syllables such as /ba/. The output signals exhibit a homogeneous, stereotypic voice quality. Because of its additive procedure, this method might allow us to implement a variety of further acoustic aspects of the human speaking voice in a well-controled manner.
Inversion of penetrable obstacles from far-field data on narrow angular apertures
Authors: Warner J. A. , Ghosh Roy D. N. , Bucaro J. , Couchman L.
Published: July 2002

Reported in this paper are reconstructions of shape and material parameters of two-dimensional, homogeneous, acoustic, penetrable obstacles of arbitrary cross-sections which are immersed in an infinite, homogeneous ambience. Reconstructions are based on the far-field scattering patterns of multiple incident plane acoustic waves. For remotely acquired data, practical necessities require not only that the entire data collection region be less than 2π, but also that each received “sees” the object over as narrow an angular aperture as possible. The inversions presented here were obtained under such conditions. Two types of data were used for each incidence namely, “near-monostatic” fields of narrow angular apertures (the narrowest aperture reported is 2°), and a “duostatic” geometry consisting of backscatter plus one other receiver angle. These data sets were acquired for a series of incident angles. The theoretical formalism for inversion is algebraic in nature, requires no integral equation, and possesses a number of advantages for the implementation of a Gauss–Newton type of inversion that was used in this study. Moreover, the algorithm is shown to be inheritently parallelizable.
Ultrasonic diffraction by a square periodic array of spheres
Authors: Henderson Benjamin K. , Kinra Vikram K. , Gonzales Albert W.
Published: July 2002

Shear waves propagated as a result of the diffraction of a broadband normally incident plane ultrasonic longitudinal pulse by a square periodic array of spherical elastic inclusions are measured at specific angles from the normal. As expected, peaks in the spectra were observed at frequencies given by the condition of constructive interference.
Literate writing and collegial citing
Authors: Pierce Allan D.
Published: July 2002

In the present editorial, the Editor-in-Chief of the Journal explains the processes by which manuscripts are handled when they are submitted for publication. Various categories of problem papers are described, and it is emphasized that the outcome of the review process is not always predictable. Metrics for measuring paper quality and journal quality are reviewed and discussed. Arguments are given to the effect that the quality of a paper and its chances of being selected for publication will be considerably improved if the authors adopt a philosophy of literate writing and collegial citing. The detailed meaning of these phrases is discussed with accompanying examples, including the case of a paper by J. J. Waterston, the publication of which was delayed for 47 years until the paper was rediscovered by Rayleigh.
Recent developments in the theory of ground vibration boom from high-speed trains
Authors: Krylov Victor V.
Published: July 2002

Generation of ground vibration boom by high-speed trains was theoretically predicted in 1994 by the present author. The first experimental observation of this phenomenon was reported in 1997 by C. Madshus, who worked with his team on the assessment of the newly opened high-speed railway line from Gothenburg to Malmo in Sweden. The ground on the site of observation was very soft, with Rayleigh wave velocity of only 45 m/s. Therefore, for train speeds as low as 160 km/h, this Rayleigh wave velocity could be exceeded and the ground vibration boom observed. It is now well understood that ground vibration boom represents a serious hazard for the built environment, especially in the cases where high-speed lines are built on very soft soil. The present paper reviews the current status of the theory of ground vibration boom from high-speed trains. Among the problems to be discussed are contributions of different generation mechanisms, effect of track wave resonances on generated ground vibrations, effects of layered geological structure of the ground, waveguide effects of the embankments, and focusing of generated waves due to the track curvature. The results of theoretical calculations are compared with the existing experiments. [Work supported by EPSRC.]
Three approaches to the perceptual evaluation of audio compression methods
Authors: van de Par Steven , Kohlrausch Armin
Published: July 2002

The compression of raw digital audio data is commonly accomplished by coding the audio data into a representation where part of the information present within the original data is lost. Upon playback this loss of information reveals itself in terms of various distortions, whose audibility depends on the coding method used. Therefore, the success of a coding method is determined by the human auditory perception of coding distortions. Three approaches to the perceptual evaluation of coding methods will be discussed. The first deals with the audibility of coding errors and is useful for methods that aim to achieve audio that is indistinguishable from the original. The second approach measures the degree of perceived degradation of coded audio, allowing comparison of different coding schemes which introduce different types of clearly audible distortions. The third approach deals with perceived intrinsic quality. For the assessment of quality, the observer is assumed to have no knowledge of the original signal. This approach is useful in situations where the original is not available to the observer. Here a judgment about quality is reached on the basis of the observers’ expectations with regard to the type of audio signal heard.
The investigation of vibroacoustical activity of the combined fuel pump
Authors: Lenchine Valeri V. , Kruchkov Alexander N. , Prokofiev Andrei B. , Shakhmatov Evgeniy V.
Published: July 2002

A theoretical and experimental investigation of the fuel pump for a gas turbine engine is described. The combined pump consists of blade and gear units. Under the pump exploitation the graphite bearing of the blade unit was being destroyed due to the high level of vibroacoustical loading at the resonant working conditions. The complex dynamic model of the pump was created to estimate pulsation and vibration productivity of the pump. The mechanism and sources of intensive vibroacoustical stresses were identified. The complex test of the fuel system allowed us to define parameters of pulsing liquid, vibration of the pump (including natural frequencies), oscillation of torque and rotation of the driving shaft, and sound power of the pump. The test’s results have good coincidence with the modeling data and confirm the hypothesis regarding the reason for the bearing destruction. The facilities to decrease vibroacoustical stresses were proposed after analyzing the dynamical characteristics of the fuel system. The effectiveness of the facilities was proved by modeling and natural experiments. As a result of the research, vibration, pulsation, and noise activity of the pump were reduced significantly, and the defect connected with the destruction of the bearing was eliminated.
Use of structured, interactive interviews in retrospective noise exposure assessment in an occupational epidemiologic study
Authors: Prince Mary M. , Waters Martha A. , Anderson Robert R. , James Richard R.
Published: July 2002

As part of a NIOSH study examining factors affecting hearing conservation program (HCP) effectiveness, a job-noise exposure matrix was constructed using these data sources: (1) task-based sound level survey data; (2) noise exposure data (dosimetry and sound level surveys) provided from plant historical reports; (3) information on process changes and engineering controls; (4) interviews with plant personnel (in engineering and safety departments); and (5) detailed work history data from personnel records for each employee in the plant HCP. For plants in which changes in exposures have occurred due to engineering control and process changes, exposure estimation becomes a challenge when there are data gaps in exposure and process changes. This paper discusses how data from structured employee interviews can be used in conjunction with available quantitative, records-based data to reconstruct processes and machinery/layout history. The goal was to characterize how noise exposure determinants (manufacturing environment, equipment, processes, shift lengths) have changed and to estimate exposure by department, job, and era. The first step was to identify employees for interview whose jobs were located in departments where exposure data were sparse or nonexistent. Data collection efforts were then geared towards reconstructing noise exposure for specific departments and jobs over time.
Avalanches, Barkhausen noise, and disorder-induced critical behavior
Authors: Dahmen Karin
Published: July 2002

Hysteresis loops are often seen in experiments at first-order phase transformations when the system goes out of equilibrium. They may have a macroscopic jump, roughly as seen in the supercooling of liquids, or they may be smoothly varying, as seen in most magnets. We have studied the nonequilibrium zero-temperature random-field Ising model as a model for hysteretic behavior at first-order phase transformations. As disorder is added, one finds a transition where the jump in the magnetization (corresponding to an infinite avalanche) decreases to zero. At this transition the model exhibits power law distributions of noise (avalanches), universal behavior, and a diverging length scale, which should be detectable in acoustic emission and other noise measurements. We study universal properties of this critical point using renormalization group methods and numerical simulations. Connections to experimental systems such as athermal martensitic phase transitions (with and without ‘‘bursts’’) and the Barkhausen effect in magnetic systems will be discussed. Similar ideas can also be applied to the interpretation of the Gutenberg–Richter scaling law in the statistics of earthquakes.