bluuebunny/crossref_metadata_2025 huggingface dataset:
Separating nonlinear propagation and cavitation effects in HIFU
Authors: Reed Justin , Bailey Michael , Nakazawa Marie , Khokhlova Vera
Published: October 2013

HIFU waves can effectively destroy tumors or stop internal bleeding. The primary physical mechanism in HIFU is the conversion of acoustic energy into heat, which is often enhanced by nonlinear acoustic propagation and nonlinear scattering from bubbles. The goal of this work is to study and separate the effects of nonlinear propagation and cavitation on HIFU heating of tissue. Transparent polyacrylamide gel was used as a tissue-mimicking phantom. The phantom contained protein that turned opaque at high temperature. The lesions were produced for the same time-averaged intensities, but with variation of acoustic pressure amplitude combined with different duty cycles. A computer program was written to quantify the size and shape of lesions captured on CCD. Substantial increase of the lesion size was observed with high-amplitude waves. In order to separate the two effects, the experiments were repeated under static pressure greater than the pressure amplitude of the sound waves, which suppressed cavitation. It was found that with the same time-averaged power, a shorter, higher amplitude pulse creates a lesion faster and grows the lesion larger, than a longer, lower amplitude pulse. Cavitation was found to play a subtle role in the initial formation of the lesion. [Work supported by NIH, NSF, NSBRI.]
The effect of surface-active solutes on acoustic cavitation bubble populations
Authors: Lee Judy , Kentish Sandra , Ashokkumar Muthupandian , Grieser Franz
Published: October 2013

Ultrasound in liquids can cause bubbles to grow to the resonance size via either the process of rectified diffusion or bubble-bubble coalescence. At the resonance size bubbles collapse and emit light, known as sonoluminescence (SL). In this study the effect of surface-active solutes on the initial growth of the active bubble population in the presence of ultrasound (a train of 4 ms pulses of 515 kHz) was monitored. This was achieved by following the SL intensity emitted by the active bubbles, until an equilibrium population of active bubbles was reached, as indicated by a maximum SL intensity. The number of pulses required to reach the maximum SL intensity was found to increase with increasing solute concentration to a maximum and then decrease. The effect of the same surface-active solutes on the total bubble volume in the presence of ultrasound was also investigated. A sharp decrease in the bubble volume is observed with increasing solute concentration. This decrease is believed to be the result of the inhibition of bubble–bubble coalescence. A correlation between the number of pulses required to reach the maximum SL intensity and the bubble–bubble coalescence data will also be discussed in the presentation.
Gas mixing diagnostics using acoustic absorption measurements
Authors: Cottet Aurelien , Meyers Andrew , Scarborough David , Lieuwen Tim
Published: October 2013

This paper demonstrates the use of acoustic absorption measurements to quantify the level of mixing between two gases. This work is motivated by the need for quantification of mixing effectiveness in a number of applications, such as in fuel/air preparation in combustion systems or various process control applications in chemical plants. The basic idea of the technique is to interrogate the medium with acoustic waves in the 20–200 kHz region where vibrational relaxation processes are the dominant factor affecting absorption. Our approach takes advantage of the fact that the relaxation frequency for a particular gas is often a strong function of the other species it is in molecular contact with. Thus, the relaxation frequency of a dual component gas mixture can vary substantially with the level of molecular mixedness of the constituent species. We present experimental data illustrating the technique which show that the level of acoustic absorption varies by a factor of five, depending upon whether the constituent gases are unmixed or perfectly mixed. These values agree favorably with theoretical results generated from classical acoustic absorption equations and empirical values of relaxation frequencies.
Effects of congruency on localization of audiovisual three-dimensional speech sounds Part IIa
Authors: Riederer Klaus A. J.
Published: October 2013

Part two of the current study [J. Acoust. Soc. Am., this issue] investigated localization of virtual audiovisual speech under exactly the same conditions. Perceived directions were signified by pushing keypad-buttons. Inside-the-head localization occurred almost only for the median-plane stimuli, being insignificant of the stimulus type (7.62% congruent, 9.38% incongruent, and 6.54% auditory-only) and disregarded from further analyses. The mean of correct answers was 46.81%. Factorial within-subjects ANOVA showed no significance on acoustic stimuli (/ipi/, /iti/) or stimulus type but showed strong dependence on direction (p=0.000015) and its interactions with acoustic stimuli (p=0.015374) and stimulus type (p=0.00812). Reaction times were highly dependent on direction (p=0.000002). From the 384 frontal location answers (azimuths 0°, ±40°) 25.52% congruent, 28.39% incongruent, and 28.65% auditory-only were perceived as backward confused, for 0° azimuth only the corresponding values were 28.13%, 28.13%, and 35.94%. Back–front confusions were 13.80%, 9.64%, and 8.85% (azimuths 180°, ±130°), and 18.75%, 14.06%, and 14.06% (azimuth 180°). Seeing the (congruently) talking face biased the localization more to the front, especially for the median-backward sounds. Obviously, vision overcomes weaker monaural localization cues as in the ventriloquism effect [Driver, Nature (London) 381, 66–68 (1996)]. [Work supported by Graduate School of Electronics, Telecommunication and Automation.]
Vibrations in buildings due to helicopter operations from rooftop heliports
Authors: Zapfe Jeffrey , Ungar Eric
Published: October 2013

Most major hospitals are equipped with rooftop heliports. This paper explores the impact of helicopter-induced vibrations inside the host building, particularly as they impact the operation of sensitive equipment. Helicopter-induced forces are characterized for two helicopters: a Eurocopter BK-117C1 and a Robinson R44. Force time histories show that the greatest forces occur just prior to touchdown and just after liftoff. Force spectra show that the principal dynamic forces occur at the blade passage frequency and amount to 2% to 14% of the helicopters weight for the BK-117C1 and R44, respectively. The force data is used to predict vibration in a planned hospital building.
Temporal attractors for speech onsets
Authors: Port Robert , Oglesbee Eric
Published: October 2013

When subjects say a single syllable like da in time with a metronome, what is the easiest relationship? Superimposed on the metronome pulse, of course. The second easiest way is probably to locate the syllable halfway between pulses. We tested these hypotheses by having subjects repeat da at both phase angles at a range of metronome rates. The vowel onset (or P-center) was automatically obtained for each token. In-phase targets were produced close to the metronome onset for rates as fast as 3 per second. Antiphase targets were accurate at slow rates (∼2/s) but tended to slip to inphase timing with faster metronomes. These results resemble the findings of Haken et al. [Biol. Cybern. 51, 347–356 (1985)] for oscillatory finger motions. Results suggest a strong attractor for speech onsets at zero phase and a weaker attractor at phase 0.5 that may disappear as rate is increased.
Acoustical study of the development of stop consonants in children
Authors: Imbrie Annika K.
Published: October 2013

This study focuses on the acoustic patterns of stop consonants and adjacent vowels as they develop in young children (ages 2;6–3;3) over a six month period. The acoustic properties that are being measured for stop consonants include spectra of bursts, frication noise and aspiration noise, and formant movements. Additionally, acoustic landmarks are labeled for measurements of durations of events determined by these landmarks. These acoustic measurements are being interpreted in terms of the supraglottal, laryngeal, and respiratory actions that give rise to them. Preliminary data show that some details of the child’s gestures are still far from achieving the adult pattern. The burst of frication noise at the release tends to be shorter than adult values, and often consists of multiple bursts. From the burst spectrum, the place of articulation appears to be normal. Finally, coordination of closure of the glottis and release of the primary articulator is still quite variable, as is apparent from a large standard deviation in VOT. Analysis of longitudinal data on young children will result in better models of the development of the coordination of articulation, phonation, and respiration for motor speech production. [Work supported by NIH Grants Nos. DC00038 and DC00075.]
Age-related changes in the anticipatory coarticulation in the speech of young children
Authors: Parson Mathew , Lloyd Amanda , Stoddard Kelly , Nissen Shawn L.
Published: October 2013

This paper investigates the possible patterns of anticipatory coarticulation in the speech of young children. Speech samples were elicited from three groups of children between 3 and 6 years of age and one comparison group of adults. The utterances were recorded online in a quiet room environment using high quality microphones and direct analog-to-digital conversion to computer disk. Formant frequency measures (F1, F2, and F3) were extracted from a centralized and unstressed vowel (schwa) spoken prior to two different sets of productions. The first set of productions consisted of the target vowel followed by a series of real words containing an initial CV(C) syllable (voiceless obstruent–monophthongal vowel) in a range of phonetic contexts, while the second set consisted of a series of nonword productions with a relatively constrained phonetic context. An analysis of variance was utilized to determine if the formant frequencies varied systematically as a function of age, gender, and phonetic context. Results will also be discussed in association with spectral moment measures extracted from the obstruent segment immediately following the target vowel. [Work supported by research funding from Brigham Young University.]
A preliminary ultrasound study of velar fronting
Authors: Wodzinski Sylvie M. , Frisch Stefan A.
Published: October 2013

The purpose of this study is to (1) evaluate the effectiveness of ultrasound imaging to measure velar consonant closure location, and (2) conduct a thorough study of velar fronting by measuring several productions of velar stops in the context of every English vowel. Word onset velar stops were measured in both words (CV or CVC) and nonwords (VCV) within a carrier phrase. Other coarticulatory influences were minimized by using words with no coda or labial coda consonants (e.g., ‘‘Say a gap again,’’ ‘‘Say /oIkoI/ again’’). Measurements were made at the point of maximal closure. Closure location was measured using the radial angle from the center of the ultrasound probe to the center of the velar closure. Pilot data for one subject has been analyzed to date. Closure location appears consistent across all central and back vowels. For front vowels, the degree of fronting of the velar appears to be correlated with the frontness of the vowel. Measures of closure location for diphthongs followed the back vowel pattern in the word targets. For nonwords, the closure location was influenced by the preceding diphthong offset quality and the following diphthong onset quality. Theoretical implications for the phonetics/phonology interface will be discussed.
The relative amplitude of vowel formants: Acoustic analysis
Authors: Jacewicz Ewa
Published: October 2013

Acoustically, vowels as speech signals transport power, which is expressed in their overall intensity level. This power varies intrinsically with vowel category and with its immediate consonantal context. These seminal findings [House and Fairbanks, J. Acoust. Soc. Am. 22, 105–113 (1953)] have received little systematic consideration over the past 50 years. The present work is a partial replication and extension of the House and Fairbanks study to formant levels, providing a set of data on intensity variations for eight selected American English vowels. Parametric investigation includes overall rms amplitude, amplitude of F0, and relative amplitudes of formants F1–F4. The study examines how the relative levels of particular formants contribute to the overall vowel intensity and how this distribution changes in consonantal contexts. Changes in vowel intensity (overall intensity and that of the first four formants) as a function of the consonantal context (both symmetrical and asymmetrical) are examined for each consonantal feature: place and manner of articulation, and voicing. Additionally, the intrinsic intensity is measured from sustained vowels recorded in isolation. The results are discussed in relation to the contributions of primary (i.e., formant frequency pattern) and secondary cues to vowel identity. [Work supported by NIDCD R03 DC005560−01.]
Orthography and underlying form in incomplete neutralization
Authors: Warner Natasha , Good Erin , Jongman Allard , Sereno Joan
Published: October 2013

Either orthographic distinctions or underlying morphological distinctions might cause incomplete neutralization. Much previous work has found small durational differences between pairs such as German ‘‘Rad’’ ‘‘wheel’’ and ‘‘Rat’’ ‘‘advice,’’ which are traditionally said to be neutralized to [rat] in both cases. Incomplete neutralization effects are stronger when the task emphasizes orthography, and when the underlying distinction is orthographically encoded. Previous work by the authors investigated a case where orthography differs, but the underlying form of the two words is arguably the same, e.g., Dutch ‘‘heten’’ ‘‘to be called’’ and ‘‘heetten’’ ‘‘they were called,’’ both /he:tən/. Incomplete neutralization was found, indicating a role for orthography rather than an underlying form. However, that case may also be interpreted as having a difference in the underlying form because of the past tense morpheme /-t/ in ‘‘heetten.’’ The current work investigates pairs which have the same underlying morphological difference, but no difference in spelling, e.g., ‘‘(ik) laat’’ (/la:t/) ‘‘(I) leave’’ and ‘‘(hij) laat’’ (/la:t-t/) ‘‘(he) leaves.’’ These pairs show no significant durational differences, despite an experimental design with quite high power. Thus, incomplete neutralization effects can be caused by an orthographic difference, but cannot be caused by this type of morphological difference.
Comparison of human, canine, and ovine laryngeal dimensions
Authors: Kim Moon J. , Hunter Eric J. , Titze Ingo R.
Published: October 2013

Geometric measurement on the laryngeal skeleton is a fundamental step in laryngeal studies, especially in biomechanical modeling. Traditionally, canine larynges have been used as models of the human larynx because of their similarity in size and gross structure, but the search continues for an alternative model because of the diminishing availability of the canine species for research in the U.S. In this study, a revised methodology for defining and labeling laryngeal framework parameters was proposed. Ovine laryngeal cartilages were measured and compared to those of human and canine cartilages previously reported in the literature. The ovine cricoid, thyroid and arytenoids cartilages were significantly different from the human and canine. Also, the lack of a definite border between the true and false vocal folds revealed that the ovine model may not always be suitable for a direct comparison to the human larynx in phonation.
Detection in acoustics
Authors: Sibul Leon H.
Published: October 2013

An overview of classical detectors and their applications to acoustics is presented. Neyman-Pearson and Bayes detectors are discussed. Log likelihood detectors are derived from the Bayes criterion and from information theoretic concepts. It is shown that matched filters, range-Doppler and wavelet domain processors, and estimator-correlators are particular implementations of the log likelihood detector. These processors have wide applications to active and passive sonar. Sequential Bayesian detectors and joint detection and estimation are discussed. Generalization of sequential Bayesian concepts has applications to information fusion from multiple sensors and net-centric processing. Basic properties of the receiver operating characteristics (ROC) are reviewed and applied to different detectors. An important current research topic of detection in uncertain/random media is discussed. Detectors in uncertain/random media can be characterized by mean and variance of the random receiver operating characteristic.
Study of environmental sound source identification based on hidden Markov model for robust speech recognition
Authors: Nishiura Takanobu , Nakamura Satoshi
Published: October 2013

Humans communicate with each other through speech by focusing on the target speech among environmental sounds in real acoustic environments. We can easily identify the target sound from other environmental sounds. For hands-free speech recognition, the identification of the target speech from environmental sounds is imperative. This mechanism may also be important for a self-moving robot to sense the acoustic environments and communicate with humans. Therefore, this paper first proposes hidden Markov model (HMM)-based environmental sound source identification. Environmental sounds are modeled by three states of HMMs and evaluated using 92 kinds of environmental sounds. The identification accuracy was 95.4%. This paper also proposes a new HMM composition method that composes speech HMMs and an HMM of categorized environmental sounds for robust environmental sound-added speech recognition. As a result of the evaluation experiments, we confirmed that the proposed HMM composition outperforms the conventional HMM composition with speech HMMs and a noise (environmental sound) HMM trained using noise periods prior to the target speech in a captured signal. [Work supported by Ministry of Public Management, Home Affairs, Posts and Telecommunications of Japan.]
Higher-order harmonic signature analysis for loudspeaker defect detection
Authors: Thompson Shane , Pagliaro Anthony , Celmer Robert , Foley Daniel , Temme Steve
Published: October 2013

Loudspeaker assembly faults, such as a rubbing voice coil, bent frame, loose spider, etc., have traditionally been detected using experienced human listeners at the end of a production line. Previous attempts to develop production measurement systems for on-line testing typically analyze only low-order harmonics for the primary purpose of measuring total harmonic distortion (THD), and thus are not specifically designed to detect defective rub, buzz, and ticking sounds. This paper describes a new method wherein the total energy of high-order harmonics groups, for example, 10th through the 20th or 31st through the 40th, are measured and analyzed. By grouping high-order harmonics and resolving their respective total energies, distinct signatures can be obtained that correlate to the root cause of audible rub and buzz distortions [Temme (2000)]. The paper discusses loudspeakers tested with specific defects, as well as results of a computer-based electroacoustic measurement and analysis system used for detection.
Comparisons of multi-source localization and spatial filtering techniques
Authors: Cook Adam J. , Stotts Steve A. , Koch Robert A.
Published: October 2013

Localization of moving sources in a multiple source environment has been investigated with simulated annealing algorithms. Results obtained, both by classical annealing and by fast simulated annealing using a rotated coordinate basis, are presented. The fast annealing method varies from the classical method in that each parameter is varied only once per temperature reduction, resulting in many fewer iteration calls per inversion. Accuracy and efficiency for these methods as a function of signal-to-noise ratio are examined using simulated data containing a weak source in the presence of a loud interferer. A method for filtering element level data prior to inversion is compared to subarray processing for effectiveness in localizing the source of interest. The effect of varying the level of the weak source relative to the level of the interferer, as well as the sources azimuthal separation, is also presented. Comparisons between an equally spaced horizontal line array (HLA) and an HLA with nonuniform sensor spacing are made. Finally, comparisons of the inversion techniques for a real data set from a nonuniformly spaced HLA at a Gulf of Mexico site, where ground truth bottom properties have been established, are discussed. [Work sponsored by ONR.]
Effects of time-reversing array deformation in an ocean waveguide
Authors: Sabra Karim G. , Dowling David R.
Published: October 2013

Active acoustic time reversal is a technique for transmitting and focusing sounds recorded in complex unknown environments back to their remote point(s) of origin. It can be accomplished with a transducer array—a time-reversing array (TRA) or time-reversal mirror (TRM) that can both send and receive sound. Nearly all prior work on underwater TRA performance has involved stationary arrays. This presentation describes how random array deformation influences TRA retrofocusing in a shallow ocean environment. Both theory and simulation results are presented for frequencies of 250, 500, and 750 Hz. For harmonic signals, randomly drifting array elements degrade TRA performance by approximately 20% when the average horizontal wave number times the root-mean-square horizontal element displacement approaches one half. For randomly rising or sinking elements, TRA performance is similarly degraded when the average vertical wave number times the root-mean-square vertical displacement reaches four or five. [Work supported by ONR.]
A near field technique for acoustic array element localization
Authors: Boyle Frank
Published: October 2013

A beamformer’s effectiveness is sensitively dependent on accurate knowledge of the array element positions. Current techniques for using acoustic data to localize array elements are generally quite effective with distant acoustic sources, but are of questionable accuracy when an array must be localized with sources located in the extreme near field. A geometric technique for localizing arrays was developed and appears effective for near field sources. The method was tested with impulsive acoustic data collected from a line array deployed in shallow water, ensonified with light bulb implosions from various positions very close to the array. The presentation will include a discussion of the technique and the experimental results.
The interface between the phonetic scientist and forensic investigations
Authors: Hollien Harry
Published: October 2013

Many scientists find the interface with criminal/civil investigations and the resulting litigation quite challenging. The great variety found among such cases and their (sometimes) shockingly grim aspects, can be most daunting. Moreover, the aid these scientists can expect when attempting to learn their responsibilities (while good) tends to focus only on the roles they will play in the courts. The reality is that they also must serve in a second domain that of investigator/consultant to law enforcement personnel and attorneys. Since training, structure and guidelines are lacking in this area, the relevant problems must be addressed (and solved) directly by the scientist. To do so, he/she must (1) learn about the parallels between laboratory investigations and forensic investigations and organize links, (2) compensate for the differences between them, (3) organize scientific personnel for collaborations in support of the needs of the practitioners, (4) adapt laboratory procedures for forensic application, (5) establish criteria for these applications and (6) develop and articulate what can and cannot be expected of these procedures. Brief case reviews will be presented to illustrate each of these issues.
Validity of voice identification
Authors: Ladefoged Peter
Published: October 2013

Courts often need expert opinion as to whether two recordings were made by the same speaker or not. Typically one voice has been recorded by an unknown speaker on a telephone answering machine and the other somehow obtained from a suspect, When such an opinion has been given, the court is bound to ask how reliable it is. There is no answer to this question. There are too many unknown factors. Were the recording conditions similar? Were both the speakers talking in the same style? Was one speaker trying for a disguise? Was there any background noise? How long was the recording? Does the suspect have family or friends with very similar voices? It would be almost impossible to set up a valid experiment that can take all the variables into account. Given two 15 minute recordings of similar material made under studio conditions an expert could state beyond a reasonable doubt whether they were made by the same speaker or not. Given a 5 second bomb threat on a noisy phone line there is no way that this could be done.
Gerrymander: An interactive musical composition for clarinet and computer
Authors: Pinkston Russell
Published: October 2013

While compositions involving traditional musical instruments and pre-recorded electronic sounds have been around since the 1960’s, it is only recently that the technology has advanced sufficiently to allow such sounds to be generated in real-time and under the direct control of a the performing musician. Gerrymander is a composition for solo clarinet and computer in which the computer processes and manipulates the sound of a clarinet in real-time to generate a dynamic musical accompaniment to the live performer. The performer is also able to interact with the computer to control various aspects of the accompaniment, including the timing of passages played by the computer and the overall pacing of the composition. The computer accompaniment is controlled primarily by tracking the fundamental pitch of the live clarinet and using it to follow a pre-recorded musical score. Granular synthesizers, pitch shifting delays, and contrapuntal harmonization algorithms, as well as a polyphonic sampler and all the necessary mixing and control logic were implemented in MAX/MSP on a Macintosh G4 powerbook. The paper will consist of a demo performance of the composition using a pre-recorded clarinet part, followed by a detailed description of the software using a video projector.
Hot topics in noise
Authors: Stinson Michael R.
Published: October 2013

Our world continues to be a noisy place and the challenge to ‘‘increase and diffuse knowledge of noise propagation, passive and active noise control, and the effects of noise’’ remains. In the last several years, noise in the classroom has emerged as one of the hotter topics: Considerable progress has been made in the underpinning research, the formulation of recommendations, and the process of educating society on the social and personal impact of inadequate acoustical conditions in classrooms. The establishment of the ANSI S12.60-2002 standard for classroom acoustics was a milestone event. Noise in cities and the understanding of our soundscapes are subjects of ongoing significance. The development of standards and regulations is a continuing process, with urban community noise regulations, aviation noise, and the preservation of natural quiet in national parks being of current concern. New methods to reduce noise are under development and include passive and active methods of noise control, techniques for modeling the performance of noise barriers, and approaches for designing product sound quality.
The use of a synthetic aperture endfire array in communications
Authors: Higley Bill , Roux Philippe , Kuperman William A.
Published: October 2013

An ultrasonic, synthetic aperture, endfire array has been constructed to study its time reversal properties. The endfire time-reversal focal spot exhibits strong spatial sidelobes not present when focusing with a vertical array, but the temporal sidelobes for an endfire focal spot are as low as those obtained using a vertical array. The minimal hardware configuration of a synthetic endfire time-reversal array using only one transmitter and one receiver makes communications a viable application. We have performed experiments to estimate data rates and corresponding bit error rates that could be achieved with such an inexpensive system utilizing either passive or active time-reversal.
Source motion and environmental effects on orthogonal frequency division multiplexed signaling
Authors: Gendron Paul
Published: October 2013

An assessment of multipath spread, coherence time, and source motion induced dilation on orthogonal frequency division multiplexed communications is made. Multipath delay spread of over 0.5 s and frequency selectivity of less than 20 Hz were observed off the Nova Scotia coast. Source motion on an 18-kHz center frequency 4-kHz bandwidth signal induce Doppler wander as large as 2 Hz/s. Implications on communications via tightly spaced orthogonal tones is addressed and bit error rates are reported.
Assessing the sound quality of a grand piano for different tuning standards
Authors: Fastl Hugo
Published: October 2013

Grand pianos are tuned to a standard frequency of 440 Hz for a4. Eighty years ago, the tuning standard was lower, around 432 Hz. In Germany, a group of music lovers insists that the sound quality of a grand piano when tuned to 432 Hz is much superior to that of the same instrument when tuned to 440 Hz. Therefore, well-controlled psychoacoustic experiments were performed to check the validity of that argument. Using a Welte–Steinway reproduction grand piano of the Deutsches Museum Muenchen, with the exception of the tuning, all other features of the pieces of music used as stimuli could be kept the same. The advantage of using the Welte–Steinway lies in the fact that reproductions of the music of famous (deceased) artists are available, who at their time performed at a lower tuning standard. Recordings of the music played at 432 vs 440 Hz were made on DAT and presented to the subjects via headphones for sound quality evaluation. Psychophysical procedures like semantic differential or preference scaling by ‘‘random access’’ that have proven successful for the assessment of sound quality in the context of car interior sounds were used in the experiments.
Sound quality and loudspeakers
Authors: Shaw Neil A. , Klasco Michael A.
Published: October 2013

The sound quality for consumer, professional, and industrial products has been found to be an important part of the product design. For many products, sound is a byproduct of the normal operation of the product. In the case of loudspeakers, the production of sound is the normal operation of the product—its job is to produce sound. A survey of the current popular means of describing and measuring loudspeakers is presented. The introduction of some new means for measuring and describing raw transducers and systems is reviewed. Areas that are still problematic are also discussed.
Basic requirements for realistic and unprejudiced evaluation of musical instruments
Authors: Wogram Klaus
Published: October 2013

In the past, the laboratory of musical acoustics of the PTB had to develop methods of subjective and objective evaluations of all kinds of musical instruments for a competition which was launched by the German ministry of economics. For this work the following questions had to be answered: (1) What makes a musical instrument play well from physical and subjective viewpoints? (2) How does the musician play the instrument, and what does he think when playing? (3) What is the influence of room acoustical parameters on sound quality? (4) How strong is the influence of prejudices concerning the brand, color, and type? (5) How can we measure the main acoustical parameters objectively? (6) What is the correlation between objective and subjective results? This presentation will give answers to these questions based on 10 years of experience with such evaluations by the author.
Sound quality of brass-wind musical instruments
Authors: Pyle Robert W.
Published: October 2013

Confronted with the phrase ‘‘sound quality’’ applied to brass-instrument sound, the typical player will respond, ‘‘Oh, you mean tone.’’ For the player, this one word lumps together all spectrum-dependent features of the sound. The player may deliberately vary tone quality depending on the type of music being performed, the other performers involved, and the performance space. After a review of those features of tone quality common to all brass instruments and the differences between the various members of the family, some more subtle questions will be addressed. How and to what extent can the player control tone color without changing equipment? How does the player choose his or her equipment? How does the instrument maker offer choices to the player? How does the tone as heard in the audience differ from that heard by the player? Time permitting, there will be consideration of the difficulties in establishing a meaningful vocabulary for the discussion of tone quality.
Radiant exchange in partially specular architectural environments
Authors: Beamer C. Walter , Muehleisen Ralph T.
Published: October 2013

The radiant exchange method, also known as radiosity, was originally developed for thermal radiative heat transfer applications. Later it was used to model architectural lighting systems, and more recently it has been extended to model acoustic systems. While there are subtle differences in these applications, the basic method is based on solving a system of energy balance equations, and it is best applied to spaces with mainly diffuse reflecting surfaces. The obvious drawback to this method is that it is based around the assumption that all surfaces in the system are diffuse reflectors. Because almost all architectural systems have at least some partially specular reflecting surfaces in the system it is important to extend the radiant exchange method to deal with this type of surface reflection. [Work supported by NSF.]
Otoacoustic emissions measured in rhesus monkeys (Macaca mulatta)
Authors: McFadden Dennis , Pasanen Edward G. , Raper Jessica , Wallen Kim
Published: October 2013

In humans, otoacoustic emissions (OAEs) are stronger in females than in males and stronger in right ears than in left. The physiological bases for these differences are unknown, but several lines of circumstantial evidence suggest that the sex difference is attributable to androgenizing mechanisms operating during prenatal development. Specifically, it appears that exposure to high levels of androgens during prenatal development diminishes the strength of the cochlear amplifiers and thus the strength of the OAEs. Sex and ear differences in OAEs have not been well studied in species other than humans. Accordingly, click-evoked OAEs and distortion-product OAEs were measured in nine female and nine male rhesus monkeys. For CEOAEs, but less clearly for DPOAEs, females exhibited significantly stronger OAEs than males. There was no consistent ear difference for either sex for either type of OAE. In order to better study the early components of the CEOAE waveform, a nonlinear procedure [Molenaar et al., Hearing Res. 143, 197–207 (2002)] was used to collect CEOAEs along with our standard (linear) procedure. This colony also contains animals of each sex that were treated with androgenic or antiandrogenic agents during prenatal development, and OAEs are also currently being measured on those animals. [Work supported by NIDCD.]
Massive gas insufflation without effect on esophageal reflectometry profiles
Authors: Raphael David T. , Arnaudov Dimiter , Benbassat Maxim
Published: October 2013

Time–domain acoustic reflectometry generates a ‘‘one-dimensional’’ image of the interior of a cavity in the form of an area–distance profile. After patient intubation with a breathing tube, the characteristic reflectometry profile consists of a constant-area segment corresponding to the length of the tube, followed either by a rapid increase in the area beyond the carina (lung) or by a sudden decrease in the area to zero (esophagus). In the cardiac arrest setting, during mistaken placement of the breathing tube into the esophagus, followed by aggressive manual ventilation, is it possible to markedly distend the esophagus, such that the esophageal profile looks like a tracheal profile? With approval of the USC IUCAC Committee, an animal study was conducted with anesthetized, tracheally intubated, and mechanically ventilated dogs. With a separate breathing tube in the esophagus, aggressive esophageal ventilation (comparable to that seen in the cardiopulmonary resuscitation setting) was accomplished with a manual resuscitation bag. A Benson Hood Labs two-microphone reflectometer was used to obtain esophageal profiles with and without the above ventilation. In this pilot study, there was no significant esophageal distention as a result of the above ventilation. [Research supported by the Alfred E. Mann Institute.]
Application of nonlinear acoustics in the atmosphere and biomedicine
Authors: Cleveland Robin O.
Published: October 2013

David Blackstock has made important contributions to understanding nonlinear processes in underwater acoustics, atmospheric acoustics, and biomedical acoustics. In this talk, two of these areas that David has been involved with are addressed by contrasting the evolution of sonic booms in an inhomogeneous atmosphere with the evolution of shock waves in lithotripsy (breaking of kidney stones by shock waves). The distortion of N waves generated by supersonic aircraft is affected by geometrical spreading and changes in the acoustic properties of the medium with altitude. In shock wave lithotripsy, the distortion of triangle waves is affected by geometrical spreading and changes in the acoustic properties due to layering of tissue types. In addition, the turbulent boundary layer near the ground and the inhomogeneous nature of tissue, means that both sonic booms and lithotripter shock waves pass through a random media. Calculations are presented using weak shock to compare the distortion that occurs in the two scenarios. Measurements of saturationlike effects are shown for a clinical shock wave therapy device. Numerical simulations for propagation through random media demonstrate the localized focusing and defocusing that can occur for both sonic booms and lithotripter shock waves. [Work supported in part by NIH and NASA.]
Propagation of finite amplitude sound through turbulence
Authors: Lipkens Bart , Blanc-Benon Philippe
Published: October 2013

Pestorius and Blackstock [‘‘Propagation of finite amplitude noise,’’ Finite-amplitude wave effects in fluids, Proceedings of the 1973 International Symposium on Nonlinear Acoustics, edited by L. J. Bjo/rno/, 1973] developed a method to simulate the propagation of finite amplitude noise in a tube. The method separates the effects of nonlinear distortion and absorption and diffraction. The nonlinear steepening of an arbitrary waveform is performed in the time domain. The absorption and diffraction effects are implemented in the frequency domain. This method has been used widely for finite amplitude wave propagation. Lipkens and Blanc-Benon [‘‘Propagation of finite-amplitude sound through turbulence: a geometrical acoustics approach,’’ C. R. Acad. Sci. Paris, Ser. IIb 320, 477–484 (1995)] used the Pestorius model to simulate the propagation of N waves through turbulence. Linear geometrical acoustics is used to trace rays through individual realizations of a turbulent field. A nonlinear transport equation describes the propagation of sound through turbulence. The equation is solved using the Pestorius algorithm. The results indicate that the equivalent nonlinear distortion after propagation through turbulence is always less than that for the homogeneous case. In addition, the effect of a random velocity field is more pronounced that that of a random temperature field.
The profile of a weak shock wave in an unconsolidated medium
Authors: Naugolnykh Konstantin
Published: October 2013

The propagation of a high intensity sound wave is determined mainly by the nonlinear and dissipative effects. If the initially sinusoidal wave is intensive, the steepness of the wave fronts increases, resulting in the occurrence of a discontinuity in each period of the wave. On the other hand, the influence of dissipative processes tends to smooth the wave profile, diminishing the gradients of velocity and temperature. Consequently, during the propagation of the intense wave its profile is forming as a result of the balance of nonlinear and dissipative effects. Many aspects of the high intensity sound wave evolution were described in the set of papers of D. T. Blackstock. The standard nonlinear medium with viscosity and thermal conductivity was considered. However, later, M. J. Buckingham has developed the theory of sound propagation in saturated marine sediments which includes a new dissipation term representing internal losses arising from interparticle contacts. The balance of nonlinearity and dissipation in such a medium has specific features that are considered in the present paper.
A brief history of the nonlinear acoustics of rocks
Authors: TenCate James A.
Published: October 2013

Much of the early measurements done to study the nonlinearity of rocks in the late 1980s were analogs to many of the classic nonlinear acoustics experiments performed by students working under the watchful eye of David Blackstock. However, it soon became apparent that nonlinear waves in rocks did not behave as expected. Wave propagation measurements in a long waveguide (a sandstone core) did not generate the usual harmonic dependencies. The nonlinear resonance of a long thin bar of sandstone did not look at all like the nonlinear resonance of a tube of air. A host of other experiments produced equally puzzling behavior. In general, waves in the rock experience considerable nonlinear distortion, exhibit peculiar hysteresis, have memory, and have confounded researchers looking for a tidy theory to describe them. Moreover, it has recently been discovered that rocks are but one member of a larger class of materials—most all of which are granular—which all exhibit similar behavior. We describe all these experiments and how the results drove us away from classical nonlinear acoustics to new theoretical descriptions and applications. [Work supported by Office of Basic Energy Sciences, Geosciences.]
Prediction of damped circular cylindrical shell vibration using energy flow analysis
Authors: Klos Jacob , Bernhard Robert J.
Published: October 2013

Approximate energy prediction tools are gaining popularity in the field of engineering noise control because of the need to quickly predict the high frequency dynamic response of complex systems. One approximate energy prediction tool commonly used is statistical energy analysis. However, many problems encountered in the field of engineering noise control do not satisfy the assumptions of lightly damped, lightly coupled systems. A second method, energy flow analysis, has been proposed for the case of moderate damping and coupling. The application of energy flow analysis to plates and beams is well documented in the literature. However, applications of energy flow analysis to shells of curvature are limited and need to be addressed. Two approaches for modeling radial vibration of damped circular cylindrical shells using energy flow analysis are proposed and verified in this presentation. The formulations of the solutions are discussed. Qualitative and quantitative comparisons of the responses predicted by the energy flow models to analytical predictions are made. From the comparisons, it is concluded that energy flow analysis provides a valid method to model radial vibration of circular cylindrical shells subjected to a radial excitation both above and below the ring frequency of the cylinder.
Vibration of in-vacuo elliptic cylindrical shells
Authors: Boisvert Jeffrey E. , Hayek Sabih I.
Published: October 2013

The equations of motion for the vibration of elliptic cylindrical shells of constant thickness were derived using a Galerkin approach. The elastic strain energy density used in this derivation has seven independent kinematic variables: three displacements, two thickness-shear, and two thickness-stretch. The resulting seven coupled algebraic equations are symmetric and positive definite. The shell has a constant thickness, h, finite length, L, and is simply supported at its ends, (z=0,L), where z is the axial coordinate. The elliptic cross-section is defined by the shape parameter, a, and the half-length of the major axis, l. The modal solutions are expanded in a doubly infinite series of comparison functions in terms of circular functions in the angular and axial coordinates. The natural frequencies and the mode shapes were obtained by the Galerkin method. Numerical results were obtained for several h/l and L/l ratios, and various shape parameters, including the limiting case of a simply supported cylindrical shell (a=100). [Work supported by ONR and the Navy/ASEE Summer Faculty Program.]
The effect of bearing properties on the eigenvalues of a rotordynamic system
Authors: Ginsberg Jerry H. , Wagner Benjamin B.
Published: October 2013

Natural frequencies and associated modal damping ratios are important in the diagnosis of rotating machinery problems. This work examines how the modal properties of a rotating shaft/disk system are affected by changes in rotation rate, lubricant viscosity, and bearing clearance. The system under analysis is a uniform, elastic, rotating shaft with a single, rigid disk concentrically mounted to the shaft away from mid-span. The shaft is supported by short-length, plain journal bearings. Standard lubrication theory is used to generate the stiffness and damping matrices for the bearings. The clearance and lubricant viscosity are independently adjustable at each bearing. A Ritz series expansion is used to generate the mass, stiffness, and gyroscopic matrices describing the shaft and disk. The combined action of the bearings and shaft/disk system is represented by stationary and rotational inertia, stiffness, and internal and external damping. A nonsymmetric generalized eigenvalue problem solver is used to calculate system eigenvalues from the system matrices over the speed range of interest. The behavior of the system is quantified in terms of dependence of the real and imaginary parts of system eigenvalues on the rotation rate. The real part of the eigenvalue is proportional to the modal damping ratio, and the imaginary part is the natural frequency. The analysis results include plots of natural frequency and damping ratio versus mode for varying bearing clearance and viscosity.
Effect of modal overlap factor on the ray tracing analysis of the curved beam structure: A computational study
Authors: Jeong Cheol-Ho , Ih Jeong-Guon
Published: October 2013

Ray tracing method (RTM) of the geometrical acoustics area is recently known to be useful for the evaluation of spatial distribution of energy density and power flow of vibrating structures at high frequencies. In this study, the spatial distribution of vibrational energy and power flow of curved beam and its connected structures are of interest. Longitudinal, flexural, and torsional waves are considered using the Euler–Bernoulli beam theory. In the analysis of spatial distribution, the band-averaged RTM result varies smoothly in space without local fluctuations. This means that the RTM result can represent a similar tendency to the traveling wave solution. An accuracy of the analysis depends on the modal overlap factor (MOF), which is the function of the length of the beam, frequency range, and structural loss factor. The effect of changing each parameter is investigated and discussed. Similar to other high frequency methods such as statistical energy analysis and power flow analysis, the results become close to the traveling wave solutions as the modal overlap factor increases. [Work supported by the BK21 project and NRL.]