bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical limits on the performance of active vibration isolation systems
Authors: Ryaboy Vyacheslav M.
Published: July 2012

Two fundamental issues in active vibration isolation are optimal actuators/sensors placement and optimal control algorithms. In this work, a general approach to active vibration isolation is pursued, with the intent of finding the limitations on the isolation performance that would be valid for all possible active force distributions independent of the particular control algorithms employed. The limiting performance is estimated in terms of isolation efficiency, frequency domain, and work performed by active forces on system displacements, considered a measure of the control effort. These estimates are derived for a general multi-DOF system and expressed as exact inequalities in explicit analytical form. The results show that physical limitations do exist on the efficiency of a generic active vibration isolation system. The principal differences in this respect are discussed between free and supported systems, absolute and relative motions, force and kinematic excitations. Limiting performance estimates can help set design goals for isolation systems. Active force distributions emerging from limiting performance analyses assist in finding rational system configurations and optimal controls. Minimum active work, expressed in terms of passive subsystem parameters, provides a criterion for optimization of a structure as a potential host for an active vibration control system.
Tuned passive vibration suppression using linear electro-mechanical coupling
Authors: Anderson Michael J. , Anderson Tony J. , Zornik William , Hocut Christopher , Blotter Jonathan D.
Published: July 2012

One proposed method to suppress vibrations of a mechanical structure is to couple the energy of vibration to an external electric shunt circuit. Coupling of the mechanical energy to the electric circuit is accomplished with a piezoelectric transducer attached to the structure. Significant amounts of mechanical energy can be dissipated by the shunt, but a large inductor is required. In this presentation, we describe an alternative approach that replaces the shunt with a linear passive electric circuit that is connected to another piezoelectric transducer attached to the structure. Even though the electric circuit does not contain an inductor, it is still possible to dissipate significant amounts of mechanical energy in the connecting circuit. The mechanism of energy dissipation in the electric circuit is similar to, but not identical to, that exploited by a tuned electric shunt. Inductance, however, is provided by mutual coupling of piezoelectric transducers on the structure.
Acoustic and perceptual speaker normalization
Authors: Adank Patti , van Hout Roeland , Smits Roel
Published: July 2012

An attempt was made to evaluate the performance of several methods for speaker normalization in both the acoustic and the perceptual domain of speech. This was done by comparing the acoustic distributions applied to the same vowel data and further by comparing the acoustic distributions to the perceptual distributions of the vowel data. The normalization methods included, among others, extrinsic (e.g., z-score transformation) and intrinsic methods (Bark transformation), and formant weighting (F2) and correction (F3−F2). To obtain the acoustic distributions, the normalization methods were applied to F0 and formant data from monophthong vowels in /sVs/ context of male and female speakers of Standard Dutch. The perceptual distributions were obtained through an experiment with phonetically trained listeners, whose task was to judge each vowel’s height, place of constriction and amount of rounding/spreading. The acoustic and perceptual distributions were compared using correlational- and cluster-analysis techniques. When describing the results of these tests, the focus will be on the extent to which the variation and overlap are the same in the acoustic and perceptual domains, and which normalization methods show a pattern of overlap and variation most similar in both domains. [Work supported by The Netherlands Organization for Research (NWO).]
The importance of lexical status in word recognition of familiar words and novel items
Authors: Diakoumakou Evanthia , Benki Jose
Published: July 2012

Talker variability and its effects on speech perception is an issue of central importance in word recognition research, and it is known that familiarity with a speaker’s voice improves recognition of novel words [Nygaard et al., Psych. Sci. 5, 42–46 (1994)]. In an investigation of how talker variability interacts with lexical status in the recognition of both familiar and unfamiliar words, listeners performed a closed-set identification task. A visual prime of four potential responses consisting of words and nonsense words that differed minimally phonologically was presented, followed by the audio target stimulus for identification using a response box. The experiment consisted of three 100-trial blocks. The trials were blocked according to talker variability (first block, single talker; second block, multiple talkers; and third block, single talker). Lexical status of the target stimulus varied within trials. Response times were also collected. Listeners performed better when the target item was a word in both the single and the multiple talker conditions. No significant interaction between talker variability and lexical status was found. The results suggest that for listeners lexical status is far more important than talker variability during word recognition.
The role of one’s own voice in auditory virtual environments
Authors: Pörschmann Christoph
Published: July 2012

The sound of our own voices contributes significantly to the way we perceive real and virtual environments and has strong implications on the way we speak. It allows speech to be controlled, which is of particular relevance in acoustically ‘‘difficult’’ situations, for example when speaking in a noisy environment. Starting from a model of the different pathways relevant to the perception of one’s own voice, the implementation of the model in an auditory virtual environment generator is described. The results of an auditory validation experiment show that the naturalness of one’s own voice is significantly increased when the model is applied. Furthermore, this system can serve as a tool for psychoacoustic research regarding the perception of one’s own voice. In a second experiment the implications of a plausible presentation of one’s own voice on the sense of presence in an auditory virtual environment were studied. For this purpose, the virtual environment generator was enhanced to a multiuser system so that it could be used as an auditory teleconferencing system where two or more participants were perceptually placed in one virtual room. Finally, possible commercial applications for the implemented model are identified and briefly described.
Identity priming using McGurk stimuli as primes
Authors: Oved Iris , Norrix Linda W. , Garrett Merrill F.
Published: July 2012

Research indicates that auditory and visual information is integrated during the perception of speech. Conflicting auditory and visual stimuli can result in an illusory experience known as the McGurk effect (e.g., auditory /bav/ dubbed onto a face saying /gav/ results in a perception of ‘‘dav’’). This study used a priming paradigm to investigate whether a phonemic representation for the auditory portion of a McGurk stimulus is active after the illusory phoneme is experienced. Subjects were given (nonword) prime-target conditions, including: (1) McGurk (e.g., Prime auditory /bav/ + visual /gav/ = ‘‘dav;’’ Target auditory /bav/); (2) Incongruent (e.g., Prime auditory-visual /mav/, Target auditory /bav/); (3) Identity (e.g., Prime auditory-visual /yav/, Target auditory /yav/). Results show that mean reaction times to repeat targets were fastest in the identity condition. Response times for the McGurk and incongruent conditions were indistinguishable from one another and significantly slower than the identity condition. This finding suggests that once the auditory and visual information is combined and a phonemic representation is made, the actual auditory signal is no longer available to affect processing of the target. [This work is based on ideas developed by the late Kerry P. Green and supported by NSF.]
Is what you hear what you see, even in a foreign language?
Authors: Moon Seung-Jae
Published: July 2012

Hearing someone’s voice, we immediately recognize the owner of the voice if we know that person. Even when we do not know him, we make up a certain mental image of the person. How accurate is the image triggered by the voice alone? Is the relationship between voice and the image triggered by the voice language-specific or universal? These are the issues this study addresses. Korean speech samples from 8 males and 8 females were recorded. Two pictures were taken for each speaker: one showing the whole body with the reference background so that physical characteristics may be easily compared, and the other showing only the face close-ups. 151 non-Asian subjects without any knowledge of Korean language were asked to match the voices with the corresponding pictures. The results were compared with the previous results obtained from 361 native speakers of Korean. While Korean subjects showed highly accurate matching patterns, non-Asian subjects showed much lower accuracy. The tendency to match a certain voice with a certain picture, regardless of being correct or not, was very high with Korean subjects, but much lower with non-Asian subjects. These results seem to suggest that the perception of voice is language-, or culture-specific.
Multiple eigenvalues of the time reversal operator for a small spherical scatterer
Authors: Chambers David , Gautesen Arthur
Published: July 2012

Time reverse mirrors have been used to discriminate and focus energy on individual scatterers embedded in difficult media. A time reverse mirror consists of an array of transceivers, each of which records the incident pressure field then re-emits a time reversed image of it. Prada [J. Acoust. Soc. Am. 97(1) (1995)] described this operation in terms of a time reverse operator whose eigenvalues are associated with individual scatterers in the medium. In particular, it was shown that there was a one-to-one correspondence between the eigenvalues and scatterers for the case of well separated scatterers whose density is identical to the medium. In this talk, Prada’s approached is generalized to scatterers of arbitrary densities where the scattered wave is no longer spherical. It is shown that the one-to-one correspondence between scatterers and eigenvalues of the time reversal operator is broken. For the specific case of a small spherical scatterer, there are three eigenvalues. Physical interpretations of the three eigenvalues and the implications for applications of the time reverse method will be discussed. [Work performed under the auspices of the Department of Energy by the Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.]
A talker tracking strategy for teleconferencing
Authors: Havelock David I.
Published: July 2012

Sound pickup during teleconferencing is adversely affected by room reverberation. A microphone array steered to the talker can significantly improve the quality of sound pickup but, to follow a conversation in the room, the array must be rapidly steered to alternate talkers. Furthermore, inaccurate and spurious estimates of the source direction must be ‘‘smoothed’’ to achieve accurate and stable steering. These two requirements tend to conflict in terms of system response time. One method of achieving both of these performance requirements is to maintain multiple talker trackers simultaneously and to switch between these trackers based on the dynamics of speech and conversation. The array steering performance of a talker tracking system is discussed and results for both simulated and real data are presented.
An improved broadband active noise compressor
Authors: Lan Hui , Zhang Ming , Ser Wee
Published: July 2012

As the extension of active noise equalization (ANE), an active noise compressor (ANCP) has been proposed recently in the literature to nonlinearly compress the noise power to a certain desired range instead of shifting it linearly. The algorithm uses a variable gain factor to control the dynamic range of the residual noise power. However, the controllability provided by that gain factor is inadequate. In this paper, we propose a new way to represent the gain factor. The new method takes into account the desire to accurately maintain the noise power when it is tolerable and suppress it while exceeding the unbearable level. Simulation and implementation results show that the new method outperforms ANCP in controllability and additionally in computational efficiency [J. W. Feng and W. S. Gan, IEEE Signal Process. Lett. 5, 11–14 (1998)].
Microcavitation-assisted selective surface erosion
Authors: Madanshetty Sameer I.
Published: July 2012

Cavitation is a chance-dominated process and cavitation activity cannot be readily controlled. Interestingly, our recent research in ACIM (acoustic coaxing induced microcavitation) allows us to bring about microcavitation quite readily at all surfaces of interest. Liquid-borne microparticles exposed to near threshold strength sound fields do not ordinarily cause cavitation, however, experience with ACIM indicates that cavitation by the microparticles is readily facilitated and one can bring about controlled erosion of painted and inked surfaces. Cavitation is an energy concentrator and microcavitation implosions concentrate enormous energy at points. ACIM, consequently, can generate high-energy density points on liquid-borne surfaces. Since the implosion effects are felt only locally, these high-energy density points easily remove ink/paint off surfaces while preserving the structural integrity of the underlying substrate. The presentation will demonstrate initial evidence of using silent sound and clean water-controlled acoustic microcavitation for removing xerographic ink from paper, and paint layers from metal surfaces without damaging the underlying substrates, paper and metal, respectively. More significantly such microcavitation-assisted surface erosion permits an easy method for determining the bonding strength between the thin film and its substrate. [Work supported by Navy and NSF.]
Surf-zone bubble detection using multiple techniques: The Worbarrow Bay experiment
Authors: Leighton Timothy G. , Simpson Matthew D. , Meers Steve D. , White Paul R. , Heald Gary J. , Dumbrell Hugh A. , Clarke James W. , Birkin Peter R. , Watson Yvonne
Published: July 2012

This paper describes a multisensor experiment to characterize the bubble population and its effects in the surf zone. Active bubble detectors (combination-frequency sensors, and the inversion of sound speed and attenuation) provided estimations of the bubble-size distribution, and allowed better interpretation of more novel sensors. These include acoustoelectrochemical sensors, and estimations of the bubble population from the ring-up time associated with the insonification of the population, and from the ambient noise (attention being paid to how the ringing population so determined differs from the full population measured by active techniques). [Work supported by the U.K. Defence Evaluation Research Agency and the EPSRC.]
The effects of oceanic surfactants on acoustic propagation in bubbly liquids
Authors: Jankovsky Joseph C. , Roy Ronald A.
Published: July 2012

The chemical composition of the top layer of the ocean is known to contain surface-active substances that are readily adsorbed to an air-water interface. The presence of surfactants in a liquid induces a viscoelastic stress along a two-dimensional interface. These surfactants can coat bubbles that alter their individual dynamics. A model is presented that incorporates the effects of surface viscoelasticity for acoustic propagation in bubbly fluids. The effects of both surface dilatational viscosity and surface elasticity on the phase speed and attenuation are considered. Surface viscosity is found to decrease the attenuation near bubble resonance frequencies, yet increase damping below resonance. Surface viscosity also diminishes the resonant effects for the phase speed in bubbly fluids. Both effects become significant for bubble sizes below 100 microns. The addition of surface elasticity is found to decrease the mean oscillation bubble radius, and thus shift bubble resonance to a higher frequency. The effects of the model on in situ acoustic bubble sizing methods will also be discussed. [Work supported by ONR.]
Sonoluminescence at the nanoscale
Authors: Camara Carlos G. , Weninger Keith R. , Putterman Seth J.
Published: July 2012

Sonoluminescence (SL) has been observed to be robust over a wide parameter space ranging from 8 kHz to 11 MHz. Although some lines can be discerned in the spectra of some cavitation clouds, they sit on top of a broadband ultraviolet continuum that spans to at least 6 eV. Experiments and theory indicate that the light-emitting region can reach tenths of nanometers. Although the SL mechanism and its huge parameter space remain a mystery, it has already been put to use as a surgical device. At 30 kHz it is used for internal lipectomy and at 1 MHz it is used for externally assisted lipectomy. At 11 MHz a dense cloud of light-emitting bubbles is observed in the far field of the transducer. These observations could be exploited for future uses of nonintrusive ultrasound surgery.
Methodology for analyzing perceptual criteria of urban soundscape
Authors: Manon Raimbault
Published: July 2012

The exposed study is part of a larger program which intends to constitute an urban soundscape simulator. This paper presents analyses of urban scenes with the aim of identifying parameters of sound perception for this future model. It seems that the perception of everyday urban sounds is not yet well understood by urban planning actors. However, those considerations are more and more problematic in everyday life and are becoming increasingly important for town planner recommendations. Therefore the assessment of perception indicators linked to acoustical measures is intended to help one fully understand urban acoustics phenomena. The method consisted of two simultaneous procedures on site. In order to calculate acoustical parameters, we recorded samples of soundscape that we analyzed afterwards. At the same time we observed perceptual attitudes and opinions using a semantic differential inquiry of passers-by. The locations were chosen in order to represent the main places of European city centers. Experimental results showed that five sector-related indicators could be defined. A full understanding of urban acoustical phenomena needs this multidisciplinary approach so that both physical and psychosociological parameters can be integrated in town planning.
Masked temporary threshold shift (MTTS) in odontocetes after exposure to single underwater impulses from a seismic watergun
Authors: Finneran James J. , Schlundt Carolyn E. , Dear Randall , Carder Donald A. , Ridgway Sam H.
Published: July 2012

A behavioral response paradigm was used to measure masked underwater hearing thresholds in a bottlenose dolphin (Tursiops truncatus) and white whale (Delphinapterus leucas) before and after exposure to single underwater impulses produced by a seismic watergun. Hearing thresholds were measured at 0.4, 4, and 30 kHz using a vocal response technique and a modified version of the Method of Free Response. A pre-exposure threshold was generally measured 34 min before presentation of the impulse. Post-exposure threshold measurements began within 2 min of exposure to the impulse and continued for approximately 20 min following exposure, in order to track recovery. A masked temporary threshold shift (MTTS) was defined as a 6-dB or larger increase in threshold compared to the corresponding pre-exposure measurement. The MTTS test paradigm will be discussed and preliminary MTTS and behavioral response data presented and compared to existing TTS data for odontocetes. [Work supported by ONR.]
The CSULB Mobile Science Museum: An interactive science outreach tool
Authors: McKibben James N. , Ayers R. Dean
Published: July 2012

Since 1980, a converted 27-ft recreational vehicle has been visiting local schools filled with a variety of hands-on science exhibits and activities. The Mobile Science Museum (MSM) has recently undergone a major renovation, including adding a generator. The MSM is now self-contained with inside exhibits that focus on the physical sciences, including sound, light, electricity, etc. The MSM also carries five large tables for outside activities, including a seawater touch-tank containing local intertidal animals, optical illusions, fossils, bones, etc. The majority of the exhibits have been developed or adapted for the MSM and utilize oscilloscopes, oscillators, strobes, power supplies, fans, and other equipment. University students act as docents and serve as enthusiastic role models for our young visitors. It is a compliment to the interest generated by the MSM that many of the current volunteer docents received their first exposure to the program when the MSM visited their schools several years ago. The major funding for the program has come from the CSULB Alumni Association, the Long Beach Industry–Education Council, and other individual support. The requests for visits greatly exceed the current ability to meet them, but this will improve as additional funding becomes available.
Development of line-based noise pollution reduction programs
Authors: Wearne Andrew , Heggie Richard , Stuart Suzanne , MacLeod Donald
Published: July 2012

This paper details the results of a unique Noise Pollution Reduction Program sponsored by the Rail Access Corporation of NSW, Australia. The program covers almost 200 km of rail line, located mostly within urban areas of Sydney. The initial stages of the project involved establishing a database of land sensitivities along the selected rail lines, defining all relevant rail noise sources and their characteristics and developing a suite of available noise abatement options and associated costs. The second stage of the project focused on detailed computer noise modeling of the rail lines, coupled with a site-specific field verification study involving all train types and other traffic variables. The third phase of the study involved prioritizing each line and different sections within each line through the development of a unique Community Noise Burden (CNB) index. This index involves assigning relative weightings per given section of line according to the noise components, number and type of dwellings affected, noise exceedance levels, etc. Following the priority ranking of each section of line, a Noise Pollution Reduction Program was then designed, incorporating consideration of community annoyance, cost per CNB improvement, practicality, safety and other benefits/disbenefits.
Noise and vibration control for the Los Angeles Metro Rail Construction Project
Authors: Luc Thanh
Published: July 2012

Parsons Engineering Science has been retained by the Los Angeles Metropolitan Transportation Authority as the noise and vibration consultant for construction of the 17-mile-long Metro Rail subway system for a period of more than 10 years. Throughout various construction phases, short-term and long-term noise and vibration monitoring have been conducted at sensitive receptor sites such as residences, schools, hospitals, recording studios, businesses, historic buildings, and hotels, to measure both background and construction activities. Continuous noise and vibration data are collected remotely over a computer terminal, such that levels can be monitored on a moment’s notice; our engineers can hear the actual sounds at the remote monitoring site from the office (15–20 miles away), and simultaneously receive decibel levels reported in real-time. Studies are conducted to determine the impacts of various construction activities, such as pile installation, and analyze the feasibility of various construction methodologies based on project noise and vibration compatibility criteria. Mitigation measures are developed to reduce impacts. Examples of mitigation measures included the use of noise curtain walls, noise equipment specifications, selection of construction methodologies, and various acoustical treatments for noise sources. Through the monitoring program and numerous studies, noise and vibration impacts have been successfully minimized.
The effect of damping of the disc brake squeal noise
Authors: Shin Kihong , Oh Jae-Eung , Kim Wootaek , Brennan Mike
Published: July 2012

A novel mathematical two-degree-of-freedom model is introduced to describe the dynamics of a disc brake system. The model is emphasized on the interacting dynamics between disc and pad components, and is investigated to understand the mechanisms of the disc brake squeal noise. Sensitivity analysis is studied to find unstable regions considered as the squeal state. Time signals are also collected from a set of first-order differential equations of the model. The signals are then used for phase space analysis to investigate the size of limit cycles. Both sensitivity analysis and phase space analysis are focused on the effect of damping of the system. The results show that damping treatment should be done on both disc and pad, whereas damping treatment has been done on the pad only in most practical situations.
New methods for objective evaluation of nasality
Authors: Kumada Masanobu , Kaneko Toshiaki , Ono Takahiko , Ohashi Masanao , Ishida Koji , Niimi Seiji
Published: July 2012

New methods for objective evaluation of nasality were introduced, including laser Doppler vibrometer, contact microphone system, and small microphone system. Subjects were two Japanese healthy males who speak Tokyo dialect. Tasks were sustained phonations of five Japanese vowels and /m/, repetitions of /ai/ and /mami/, and Japanese words of /shinksnsen/ and /shinbunshi/. Vibration of nasal skin was detected by laser Doppler vibrometer in terms of velocity (Nv), and by contact microphone in terms of deviation (Nc). Vibration of neck skin on larynx was detected by contact microphone (Lc). Sound radiating from nares was detected by small microphone (Nm). Sound radiating from nares and mouth was detected by standard microphone (NOm). The accelerometer system was used as standard, consisting of two pickups, one of which detected vibration of nasal skin (Na), and the other, neck skin on larynx (La). Nv/Lc, Nv/NOm, Nc/Lc, Nm/NOm were compared with Na/La. These values were normalized as the value for sustained /m/ as 1.0. Clinical use of these new methods was discussed.
Glottal characteristics of children—acoustic measures and comparison with adults
Authors: Hanson Helen M. , Stevens Kenneth N. , Ohde Ralph N.
Published: July 2012

Previous studies of vowels produced by adult speakers showed substantial individual and gender differences in acoustic parameters related to glottal characteristics [H. M. Hanson, J. Acoust. Soc. Am. 101, 466–481 (1997); H. M. Hanson and E. S. Chuang, ibid. 106, 1064–1077 (1999)]. The current study extends the earlier work to children. In pilot work, data produced by seven children (five male, two female, ages 5-8) showing no signs of speech or voice disorders were analyzed. Acoustic measures related to first-formant bandwidth, open quotient, and spectral tilt were made on the vowel /ε/ extracted from the word ‘‘red.’’ These preliminary data show, for example, that the average measure of spectral tilt (dB difference between amplitudes of first harmonic and third-formant prominence) for the children is about 14 dB greater than for adult females and about 24 dB greater than for adult males. The results suggest that, like adults, children display substantial individual differences in vocal-fold configuration. Data for additional subjects and vowels will be analyzed, and we will make measures related to aspiration noise. Mean data for children and adults will be compared and interpretation in terms of acoustic models will be proposed. [Work supported by NIH Grant DC03744.]
Eliciting speech styles in the laboratory: Assessment of a new experimental method
Authors: Harnsberger James D. , Pisoni David B. , Wright Richard
Published: July 2012

This study concerned the development of a method of eliciting controlled stimulus materials, namely sentences, varying in three speech styles: reduced, citation, and hyperarticulated. Such a method would prove useful in studying the acoustics and perception of speech styles. The reduced style was elicited by having subjects read sentences while carrying out a distractor task that involved recalling a digit sequence from short-term memory. The length of the sequence was calibrated to the individual subject via a digit span task administered prior to elicitation. It was hoped that the distractor task, serving as a cognitive load, would result in a less monitored, more naturalistic style. The citation style was elicited by having subjects read sentences from a list. The hyperarticulated style was elicited in a similar manner, except that subjects were prompted on some trials to reread the sentence again more carefully. Twelve subjects were recorded in this experiment, and the resulting sentences were acoustically analyzed and perceptually tested in a pairwise comparison task. The results showed that half of the talkers produced reduced sentences that differed acoustically and perceptually from citation sentences, while all 12 subjects produced hyperarticulated sentences that were differentiable from all others.
Direct classification of Thai monophthongs on two-dimensional acoustic–phonetic feature spaces in linear, mel, bark, and bark-difference frequency scales
Authors: Ahkuputra Visarut , Jitapunkul Somchai , Maneenoi Ekkarit , Luksaneeyanawin Sudaporn
Published: July 2012

A direct classification of nine Thai monophthongs was conducted on two-dimensional acoustic–phonetic feature spaces. Formant frequencies of a monophthong have been extracted from a stable vowel portion of a syllable nucleus. The F1 and bark-difference F1-F0 represents tongue height. The F2 and bark-difference F3-F2 represents tongue advancement. The Bayesian classifier utilizes statistical parameters, mean and standard deviation, of each monophthongs in classification. Two-dimensional feature vectors comprise two acoustic–phonetic features, F2 and F1 in linear, mel, bark, and also, bark-difference F3-F2 and F1-F0. The classification results on the F2 and F1 space are 86.3325% in linear, 84.6187% in mel, 84.2331% in bark, 79.3916% in bark-difference F2-F1 and F1-F0, and also 79.9914% in bark-difference F3-F2 and F1-F0. Considering confusion matrices, the high vowels (/i:, v:, u:/), front-middle vowel (/e:/), and center-middle vowel (/q:/) have higher results than other groups which resulted from smaller overlapping and more separability between each group compared to low- and back-vowel groups. The back vowel (/u:, o:, @:/) has more misclassification between each monophthong than in other groups. Both feature spaces in bark-difference frequency scales exhibit lower-classification results although they illustrate better vowel distribution than other scales.
Geoacoustic parameters by inversion of bottom reflectivity data from the Santa Barbara channel experiment
Authors: Chapman Ross , Hudson Danya
Published: July 2012

A method is described to estimate the range dependence of geoacoustic parameters of the seafloor from bottom reflectivity data. The data were obtained using light bulbs as sound sources in the Santa Barbara channel experiment (SBCX). Light bulbs were deployed around the SBCX FFP array that consisted of five 30-element vertical line arrays. Signals from the direct path, the surface reflected path, and the four components of the first bottom reflection were clearly resolved at each array. The inversion integrates the results from several source–array combinations to generate estimates of the seafloor geoacoustic parameters in the area around the FFP array. The reflection coefficients were determined versus angle from the direct path and bottom-reflected path signals, and inverted using a simple fluid model to estimate the seafloor sound speed and density. The estimates are consistent with the known ground truth information for the SBCX site. [Work supported by ONR.]
Sediment tomography in the East China Sea
Authors: Potty Gopu R. , Miller James H.
Published: July 2012

Sediment tomography experiments using broadband shots are planned as part of the Asian Seas International Acoustic Experiment (ASEAEX) in the East China Sea (ECS) in the year 2001. In order to gather adequate sediment information, gravity cores were taken from the experimental location during the spring of 2000. Using the gravity core data and available historic data, a sediment geoacoustic model for the region is presented. Synthetic experiments are performed with this geoacoustic model using broadband data. Various configurations of the explosive sources are tested to arrive at a suitable experimental geometry for the tomography experiment. This inversion is based on group speed dispersion of the broadband acoustic signal and is capable of estimating range-dependent sediment properties. [Work sponsored by ONR.]
The real time use of signal processing in brass performance
Authors: Plsek Thomas J.
Published: July 2012

The real time use of signal processing for brass instrument performance (specifically the trombone) provides an opportunity, as well as challenges, to create a type of hyper-instrument quite unlike most conceptions of the term. These include the expansion of the available sound palette, the problem of real time parameter control, microphone techniques, and repertoire considerations. The various types of processing used includes reverb, pitch change, delays—short time and longer looping types, distortions, and combinations of the above. One of the notions that must be accepted is that, unlike instruments whose sound is produced electronically, the processed signal, unless significantly long-delay-based processing is used, is always layered onto an acoustic output. By creatively managing the acoustic instrument and the electronic equipment, a vast array of musical resources become available to the performer enabling him/her to enhance existing performance environments, as well as find and develop new ones.
Peformances of Ballet Mécanique
Authors: Lehrman Paul D.
Published: July 2012

George Antheil’s 1924 Ballet Mécanique, written for two pianos, three xylophones, four bass drums, tam-tam, electric bells, three airplane propellors, and between 4 and 16 synchronized player pianos, is one of the great ‘‘lost’’ pieces of the 20th-century instrumental repertoire. This paper describes the efforts that were made between 1996 and 2000 to revive this remarkable piece, using modern computers, MIDI, digital samplers, and MIDI-compatible player pianos. It talks about how the project same about; the musical and technical decisions that needed to be made; the problems of transcription, synchronization, and rehearsal; and the practical, artistic, and logistical issues of presenting the piece in three different concert spaces: Durgin Hall at the University of Massachusetts Lowell, Carnegie Hall in New York, and Louise Davies Symphony Hall in San Francisco.
Quantitative practice for students at the Digital Conducting Laboratory
Authors: Marrin Nakra Teresa , Hill Gary
Published: July 2012

Students of conducting and conducting pedagogy at Arizona State University’s School of Music now have the opportunity to enhance their skills as performers and teachers with the assistance of a unique technology housed in the Digital Conducting Laboratory. Utilizing a Digital Conducting Feedback System designed by Dr. Teresa Marrin Nakra of Immersion Music, Inc., the laboratory has the capability to simulate many of the behaviors of a live orchestra rehearsal setting. The system’s unobtrusive sensor interface and interactive program recreates several fundamental ensemble-conductor interactions, particularly by reacting to the tempo, articulation, and dynamic line generated by the conductor. In addition to immediate aural feedback, the system allows conductors to review their performances via sound files, video playback, and analysis of muscle-tension profiles. The musical materials consist of a set of etudes that systematically take a conductor through a review of basic conducting gestures. Compiled and arranged by the laboratory’s founder and director, ASU Professor Gary W. Hill, the etudes are principally derived from familiar classical music, freeing the user to focus primarily on his or her conducting and the concomitant response.
Interactions among acoustics, digital signal processing, and movement
Authors: Cluett Seth
Published: July 2012

A team of architects, electronic artists, and acousticians designed a system for manipulating acoustic, haptic, and spatial information based on the motion of dancers through space. The dance structure was designed to inspire physical exploration and interaction, to sense and process resultant sounds based on this dance, and to present an immersive sound field to the dancers and observers which complemented the visual impact of the movement. A microphone system captured the sounds of the dancers’ contact with the system. An electronic sensor system tracked the location and action of the dancers. A set of digital signal processing algorithms analyzed, modified, and spatialized in real time the information collected from the environment, integrating sensory cues arriving simultaneously and rapidly via multiple modalities. A multichannel speaker system re-presented the natural and modified sounds to the acoustic environment, which in turn affected the dancers’ movements. The nature of movement through physical space, the localization of movement in both vision and audition, and the abstraction, support, and deconstruction of both modalities were studied. The results were used to design a performance by a dance ensemble that explored the synergy between movement, multimodal sensory information, and sound.
Acoustic detection distances of sperm whales in the Gulf of Mexico
Authors: Mellinger David K. , Thode Aaron M. , Martinez Anthony , Mullin Keith , Stienessen Sarah
Published: July 2012

During a cruise in June–July 2000 in the north-central Gulf of Mexico, sperm whales were acoustically detected, located, and tracked using a small-aperture hydrophone array towed at a depth of 20–100 m. Water depth was 800–2000 m. Detection ranges to groups of sperm whales were estimated on several occasions by determining the location of a calling whale or group of whales, then moving away in a straight line until the group was undetectable. The range at which sperm whales could no longer be detected, either aurally with headphones or visually in a spectrogram, was found to be 4–6 km, significantly less than the 11 km that had been estimated previously in the Gulf [Norris et al., Minerals Management Service Report 1996-0027]. To investigate this result, acoustic propagation models were run. Results from the models are shown and are used to explain the short detection distances present. In addition, propagation models are used to evaluate the effects of water depth, sensor depth, and bottom composition on detection range, which will be most useful for future attempts to predict detection ranges of sperm whale sounds. [Work supported by ONR, MMS, and NMFS.]
Hilbert spectrum of internal waves
Authors: Wang Tao , Su Tong
Published: July 2012

The newly developed Hilbert spectrum offers a powerful tool for nonlinear, nonstationary data analysis, and has found wide applications to Stokes waves, random ocean wind waves, and turbulence [N. E. Huang, Z. Shen, and S. R. Long, Annu. Rev. Fluid Mech. 31, 417–457 (1999)]. This paper presents the Hilbert spectrum of internal waves in the Yellow Sea and East China Sea. According to their intrinsic characteristic scales, the internal wave data are first decomposed into a number of modes of different time scales, designated as intrinsic mode function (IMF) components. The Hilbert transform is then applied to the IMF components to construct the frequency–time distribution of energy density, the Hilbert spectrum. It is shown that the Hilbert spectral analysis provides a new physical insight in the underlying dynamic processes of these shallow-water internal wave phenomena.
Sound in a time-dependent ocean: Implications on acoustic tomography of currents
Authors: Godin Oleg A.
Published: July 2012

Ocean is a nonstationary acoustic environment. Surface and internal waves, tides, and mesoscale eddies contribute to sound-speed and ocean surface variability on different temporal scales. Acoustic effects of the nonstationarity include violation of the reciprocity principle and signal frequency variation along the propagation path. Mathematical models of underwater sound propagation often either ignore ocean nonstationarity or account for it within the frozen-medium approximation. In this paper, accuracy of different approaches to model sound propagation in time-dependent ocean is analyzed within the frameworks of the ray theory and the adiabatic mode approximation. The theoretical approach is based on the space-time geometrical acoustics and a space-time version of the ‘‘vertical modes–horizontal rays’’ technique. While the frozen-medium approximation proves to be generally rather crude and inadequate in modeling nonreciprocity due to sound-speed time dependence, another simple technique, the quasistationary approximation, is shown to be a sufficiently accurate and efficient approach to modeling low-frequency underwater sound propagation. Contributions to ray travel time and mode-phase nonreciprocity due to medium motion and time dependence are compared for several typical current tomography scenarios. The feasibility of distinguishing between acoustic nonreciprocities due to currents and due to medium nonstationarity is discussed. [Work supported by NRC.]
Beamforming through an anisotropic, time-varying internal wave field
Authors: Finette Steven , Oba Roger M.
Published: July 2012

Shallow-water environments commonly exhibit complex spatial and temporal variations in temperature and salinity caused by internal wave activity. These quantities map into a sound-speed distribution that can significantly distort both the amplitude and phase of an acoustic field propagating through the environment. This presentation describes computer simulation results on the effect of an anisotropic, time-varying internal wave field on plane wave beamforming of a point source within a shallow-water waveguide. The (azimuthal) anisotropy is described by a solitary wave packet propagating through the region. A 3D parabolic equation code was used to propagate a 400-Hz signal through this space and time-evolving environment. Beamformed power, parametrized by receiver depth and an azimuthal angle, is illustrated for horizontal arrays and presented in terms of beam space, time, and range from the source. When the packet enters the region between source and receiving array, significant periodic beam wander and beam splitting are seen; such effects are shown to be related to horizontal refraction of energy from individual internal wave depressions forming the solitary wave packet. [Work supported by the Office of Naval Research.]
High-intensity focused ultrasound hyperthermia in nonuniform tissue phantoms
Authors: Huang Jinlan , Holt R. Glynn , Roy Ronald A.
Published: July 2012

It has been demonstrated that high-intensity focused ultrasound (HIFU) shows promising potential for stopping bleeding, both from individual blood vessels as well as from gross damage to the capillary bed. Thermal effects have been suggested to play a major role in occlusion of small vessels and also appear to contribute to the hemostasis of major blood vessels. The goal of the present work is to understand the heating process in nonuniform flow-through tissue phantoms. The experiments have been focused on a single-vessel flow-through phantom, and the studies include the prediction and measurement of temperature fields as a function of acoustic pressure, insonation time and flow rate, and investigating different insonation geometries including on-axis and off-axis insonations. The experimental data are compared to simulation results using the Westervelt equation for calculating the nonlinear acoustic field and two coupled bioheat equations for the tissue domain and the blood domain for the temperature field calculation. [Work supported by DARPA.]
Influence of chemical composition of membrane-disrupting polymers on relative cavitation activity and hemolysis
Authors: Porter Tyrone M. , Nickerson Josh , Crum Lawrence A. , Black Fiona E. , Murthy Niren , Stayton Patrick S. , Hoffman Allan S.
Published: July 2012

In previous studies, we have shown that membrane-disrupting polymers may also act as cavitation promoters. These polymers are designed to efficiently disrupt red blood cells in a pH-dependent fashion (Murthy et al.). When combined with high-intensity focused ultrasound (HIFU), there is a noted increase in relative cavitation activity and a corresponding increase in red blood cell lysis. Varying the chemical composition of the polymer (length of hydrocarbon chains, molecular weight, etc.) modifies the hemolytic and cavitation-promoting activity of the polymer. For example, the hemolytic and cavitation promoting activity of poly(ethyl acrylic acid) (PEAAc) rises as the pH of the solvent decreases from 7.4 to 6.1. However, the polymer poly(propyl acrylic acid) (PPAAc), which has a more hydrophobic pendant alkyl group, promotes cavitation and, therefore, hemolysis at a pH of 5.0, 6.1, and 7.4. Variations in the polymer molecular weight change the number of hydrophobic regions which also alters the hemolytic and cavitation activity. From these results, polymers may be designed which, when combined with ultrasound, optimize drug transport across cell membranes in a pH-dependent or -independent manner.
Detection of the malpositioned endotracheal tube via acoustic reflectometry: An in vitro study
Authors: Raphael David T.
Published: July 2012

Time-domain acoustic reflectometry can generate a one-dimensional area-distance profile of a cavity, such as the lung or esophagus. Can acoustic reflectometry be used to detect an endobronchial intubation? In an Institutional Review Board approved study, an endobronchial intubation in the right mainstem bronchus in an anesthetized patient was detected first by acoustic reflectometry, and the malposition confirmed by fiberoptic bronchoscopy. A study was initiated to determine the area-distance profile characteristics of an endobronchial intubation in an in vitro branching glass model. A symmetrical glass model (Witeg Scientific, Anaheim, CA), open at the proximal end, with two orders of bifurcation terminating in four closed distal branches, was studied. Area-distance (A-D) profiles were obtained with a customized computer-based acoustic reflectometer (Hood Labs., Pembroke, MA). With an endotracheal tube (ETT) attached to the reflectometer, area-distance profiles were obtained with the distal ETT in the following positions: the mid-‘‘trachea,’’ ‘‘carina,’’ ‘‘mainstem bronchus,’’ the second bifurcation, and the secondary ‘‘bronchus.’’ The area-distance profile features of an endobronchial intubation, as determined by this model study, are similar to those observed clinically in a patient.