bluuebunny/crossref_metadata_2025 huggingface dataset:
Locating two sound sources: The role of amplitude modulation and spectral content.
Authors: Yost Willim A. , Brown Christopher , Walling Farris
Published: July 2011

We have shown that listeners can locate two sound sources producing simultaneous sounds when the sounds are independently generated wideband noise bursts. Listeners’ localization performance is better when the sound at one source is sinusoidally amplitude modulated (AM) 180 deg out-of-phase relative the AM of the other sound as opposed to conditions in which the envelope modulation phase is the same (in-phase) for the sound at both sources. This improved localization performance can be measured up to AM rates of 200 Hz. Listeners can discriminate out-of-phase from in-phase modulation between the two sounds up to AM rates of 500 Hz. In the current study, we use filtered noises (lowpass: 125–500 Hz, highpass: 1500–6000 Hz, and wideband: 125–6000 Hz) in an attempt to determine the role interaural time and level differences play in localizing the sources of two independently generated AM sounds. The results will be discussed in terms of the cues listeners might use in localizing multiple sound sources when the sounds occur simultaneously.
Amplitude-modulation detection in reproducible modulation maskers: Correlation between Behavioral and Physiological Responses.
Authors: Zilany Muhammad , Abrams Kristina , Koch Kelly-Jo , Idrobo Fabio , Carney Laurel
Published: July 2011

The use of reproducible noise maskers in studies of detection has proven useful to extend our understanding of coding and processing of complex sounds. In an effort to reveal potential neural mechanisms for the detection of amplitude-modulation (AM) in the presence of modulation maskers, tetrode recordings were made from inferior colliculus neurons of awake rabbits using reproducible stimuli. Both rabbit and human behavioral data have been collected for the same set of reproducible maskers. The target AM and maskers were applied to the envelope of a 5 kHz carrier signal. Neural responses were recorded to stimuli with the level of target AM slightly above masked threshold for both rabbit and human. Neural detection thresholds were estimated based on average discharge rate and several temporal metrics, such as synchrony to the target AM, temporal reliability, and rapid fluctuation in the peri-stimulus time histogram (PSTH) of responses. The hit and false-alarm rates for neural detection of AM were estimated for a set of 20 reproducible AM maskers. Preliminary results suggest that some neural responses, based on mean rate, synchrony to the target AM, or the slope of the PSTH, can explain the parallel rabbit behavioral results. [Work supported by NIH-NIDCD R01-001641.]
Localization in noise and the role of forward masker fringe.
Authors: Simpson Brian D. , Gilkey Robert H. , Brungart Douglas S. , Iyer Nandini , Hamil James T. , Swayne Billy
Published: July 2011

Previous research suggests that the localization of a target sound in a masking noise is more accurate when the masker is preceded by a forward masker fringe. It is unclear what information listeners are exploiting to produce this improvement in performance. Does the fringe simply reduce spatial uncertainty (by cuing the location of the masker) or does it provide a “context” against which the onset of the signal is more easily discerned? In order to address these questions, we examined conditions in which the masker is (a) pulsed on and off with a 60 ms target (no fringe), (b) immediately preceded by a 500-ms masker fringe; or (c) preceded by a 500-ms fringe + a 500-ms gap. Masker spatial uncertainty was also manipulated by presenting the noise from a fixed and known location throughout a block, or from a location that varied across trials. The results suggest that listeners benefit from the presence of a forward masker fringe even when the masker location is known. However, localization performance is best when this fringe occurs immediately prior to the masker (i.e., no gap), suggesting that onset-related cues also contribute to the improvement in localization. [Work supported by the AFOSR]
Short-comings in direct translations of names for hearing sensations: A case study regarding the roughness sensation.
Authors: Paul Stephan
Published: July 2011

Many psychoacoustic models, now widely used, were first developed in Germany, especially at Zwickers laboratory, and originally named with German terms that correspond to hearing sensations as named by German subjects. Often the terms were readily translated into other languages, especially English and French for publication and nowadays these translations are widely used and accepted. This also applies to the concept of psychoacoustic roughness, named “Rau(h)igkeit” in German. The Munich school developed the first models to describe the sensation of Rau(h)igkeit, found to be caused by fast AM or FM modulation, also present in the spoken German “R” which initiates the term Rau(h)igkeit. Even when the direct translation of the term Rau(h)igkeit and roughness to other languages seems to be quite adequate particularly for Brazilian Portuguese it has been found, by means of subjective evaluation of different signals and signal analysis that this translation is problematic as the corresponding term in Portuguese (“aspero”) is used by naive and non-naive Brazilian subjects to name the auditory sensation due to stochastic signals, especially white noise which is unmodulated. So far the hearing sensation described as aspero does not correspond to the sensation of originally described as Rau(h)igkeit and roughness models will fail.
Comparison of modal analysis results of laser vibrometry and nearfield acoustical holography measurements of an aluminum plate.
Authors: Potter Jennifer L.
Published: July 2011

Two methods for non-contact vibration measurements are compared using modal analysis. Laser vibrometry and nearfield acoustical holography are used to measure mode shapes of an aluminum plate excited by a mechanical shaker with random noise. Laser vibrometry provides a direct measurement of the panel surface velocity, while the nearfield acoustical holography measurements are used to calculate the surface velocity indirectly. Both data sets are compared in frequency, damping, and mode shapes. The results are also compared to finite element and theoretical analyzes. Results are presented from all four approaches.
Statistically optimized near-field acoustical holography applied to a high-power jet.
Authors: Wall Alan T. , Gee Kent L. , Neilsen Tracianne B. , Sommerfeldt Scott D. , Blotter Jonathan D. , James Michael M.
Published: July 2011

The characterization of jet noise can lead to prediction of the radiated sound field and can assist in the development of noise reduction technologies. Thus, the sources and radiation of high-power jets on military aircraft are being investigated. Patch-and-scan array-based holographic measurements were made in the geometric near field of the F-22 Raptor, including more than 6000 measurement points, making this the most extensive near-field measurement of high-power jet noise to date. A set of stationary reference microphones was used to tie together amplitude and phase information between scans by the virtual coherence method. The measurement aperture was then effectively extended through implementation of an analytic continuation procedure and utilization of the rigid ground reflection. Finally, the 3-D near sound field was reconstructed using statistically optimized near-field acoustical holography (SONAH). [Work supported by the Air Force SBIR.]
Discussing the advances in the characterization of the cortical involvement in speech and hearing perception using magneto- and electro-encephalography.
Authors: Lee Adrian K. C.
Published: July 2011

Magneto- and electro-encephalography (M/EEG) are neuroimaging techniques that provide us with the high-temporal resolution particularly suitable to investigate the brain network involved in speech and hearing perception. In many of these studies, data are either interpreted at the sensor level (based on the magnetic/electric field recorded on the scalp) or at the cortical level (after making a judicious choice of the appropriate source modeling technique). There are unique challenges associated with each of these approaches in terms of data processing and, ultimately, making appropriate statistical inferences to illuminate the underlying neural mechanisms associated with the task under investigation. In this talk, the different technical challenges tackled in each of the studies presented in this session will be highlighted. Other methodological advances that are particularly relevant to experiments in the speech and hearing sciences will also be discussed.
Noise interferometry, in the geometric limit, in a multipathing environment.
Authors: Brown Michael G.
Published: July 2011

It is now well established that under commonly encountered conditions a good approximation to the transient Green’s function G(xa|xb,t) between points xa and xb can be estimated by taking the time derivative of the correlation function Cab(t) of records of ambient noise measured at locations xa and xb. We consider the relationship between Cab(t) and G(xa|xb,t) in a multipathing environment in the geometric limit, and we assume that the noise field has a broad bandwidth. Under these conditions Cab(t) for t > 0 consists of a superposition of signed step functions and two-sided logarithmic singularities that are delayed in time by the travel times of the rays connecting xa and xb. The reason that Cab has this structure is explained. [Work supported by ONR.]
Spatial coherence of acoustic reverberation and its possible use for characterization of the environment.
Authors: Godin Oleg A.
Published: July 2011

Cross-correlation function of diffuse noise fields generated by random sound sources distributed on a surface or in a volume contains valuable information about the propagation environment. It was recently demonstrated [Godin et al. Geophys. Res. Lett. 37, L13605 (2010)] that this information can be successfully retrieved and used for passive ocean acoustic tomography. However, long averaging times are typically required for underwater noise to become sufficiently diffuse and for coherent features to become pronounced. In a waveguide with rough boundaries, one might expect that waves scattered by random roughness and waves that would be generated by random sources distributed on the boundaries have similar statistics. This paper investigates the possibility of using rough surface reverberation in an underwater waveguide, instead of the ambient noise, as a source of information about physical properties of the water column. Two-point correlation function of the surface-scattered waves is calculated in the second approximation of the method of small perturbations and compared to the two-point correlation function of diffuse noise. Feasibility is discussed of retrieving deterministic travel times of sound traveling in opposite directions between two receivers from the cross-correlation of the reverberant field recorded by the receivers.
The state of the art in measurement and characterization of scattered sound.
Authors: D’Antonio Peter , Rife Brian
Published: July 2011

For over 100 years, the acoustical industry has measured and characterized sound absorption. And yet, standard measurements of the random incidence absorption coefficient, according to ISO 354 and ASTM C423-09, still do not provide an accurate answer. Nevertheless, acousticians utilize this inaccurate material property in several formulas, including Sabine, Norris–Eyring, etc., to predict a room property called the reverberation time. All measurements and predictions rely on the concept of a diffuse sound field, which is yet to be fully characterized in the standards. The field of measuring and characterizing scattered sound is in its infancy by comparison, yet in the past 3 decades much progress has been made. Two standards have emerged for measuring scattering (ISO 17497-1) and diffusion (ISO-17497-2) and the current state of the art for both will be reviewed. While much progress has been made in measuring and characterizing scattering surfaces, we still need to develop a relationship between these material metrics and a room property, which we can call diffusivity, as well as defining how to measure and characterize a diffuse sound field. This presentation is intended to be a tutorial on the evolution and current state of the art.
Counting local peaks in impulse responses for evaluation of the in-situ diffusion in concert halls.
Authors: Jeon Jin Yong , Kim Yong Hee , Vorländer Michael
Published: July 2011

This paper presents methods for identifying reflections in measured room impulse responses using a wavelet transform and counting local peaks. In a performance space, the temporal structure of the impulse response is affected by diffusive wall surfaces. Because wavelet theory assumes the original form of a reflection as a mother wavelet, scattered reflections in the impulse responses can be detected through the continuous wavelet transform. From scale model testing, it is found that the summation of wavelet coefficients increases with diffuser installation. For practical application, a method on counting local peaks at −20 dB after the direct sound is suggested as number of peaks (Np). In measured results, Np shows good agreement with wavelet coefficients. Robustness and effectiveness of Np are discussed for in-situ diffusivity evaluation.
Perception of scattering coefficient in auralized concert halls.
Authors: Vitale Renzo , Vorländer Michael , Garrido Alcázar José Augustín
Published: July 2011

The scattering coefficient has become a determinant parameter in room acoustic software because it enhances the precision of simulation results. Although there is a wide agreement on the necessity of using scattering coefficients for characterizing surfaces and pattern elements within an enclosed space such as a concert hall, there is still a lack of knowledge on the influence of this on the human perception. The primary purpose of this study is to investigate how changes in scattering coefficients of diffusing surfaces could possibly affect the perception of music among the audience in concert halls. A simplified shoebox-like geometry was used to generate binaural room impulse responses under various scattering conditions for different seats. Computer simulation results were convolved with sound examples, which were properly selected as representative of typical music textures. Results from listening tests will be shown and discussed.
Echolocation of fluttering insects by using the frequency modulated sound.
Authors: Matsuo Ikuo , Takanashi Takuma
Published: July 2011

Using the echolocation, bats can capture insects in real 3-D space. The echoes from the insect were changed with the wing beats and its orientation. In the case of emitting the constant-frequency (CF) sound, the wing beats could be estimated from the amplitude modulation and frequency modulation (FM) dependent on the Doppler-shift. In this study, the echoes were measured from several kinds of insects when both the CF and FM sounds were intermittently emitted from the ultrasonic loudspeaker. At the same time, the movements of the wing were measured by the high speed camera. The impulse responses and time-frequency pattern were computed by using the cross-correlation function and the convolution of the chirplet filters, respectively. It was examined that these patterns were related to its orientation and the wing beats, that is, the change of wing positions along the time axis. [Work supported by the Research and Development Program for New Bio-industry Initiatives.]
Environmental knowledge and operational effectiveness at the NATO Undersea Research Centre.
Authors: Becker Kyle M.
Published: July 2011

One of the primary areas of research at the NATO Undersea Research Centre (NURC) is environmental knowledge and operational effectiveness. The objective of this work is to provide environmental information in support of maritime operations from the planning stages through to real-time decision making. Generically, this is accomplished by parametrizing the environment according to need and providing the best knowledge available for each parameter including uncertainty. In practice, the environment is measured using a variety of mobile and remote sensors, including AUVs, with the aim of improving high-resolution models of the oceanographic environment. In turn, these models and measurements are used as input for operational planning and prediction tools. This talk will describe recent and upcoming experimental work at the NURC designed to test these concepts and their application to acoustic based planning and prediction tools. The goal is to demonstrate the use of these concepts to improve prediction capabilities for transmission loss and signal excess in an operational area.
Theoretical considerations for ultrasound contrast agent amplitude modulation techniques at high frequencies.
Authors: Jafari Sojahrood Amin , Kolios Michael
Published: July 2011

Increasing the nonlinear response of ultrasound contrast agents (UCAs) in response to two consecutive pulses in amplitude modulation (AM) techniques can significantly increase the contrast to tissue ratio (CTR). It has been recently shown that one way to increase the nonlinearity is to take advantage of the buckling behavior of lipid shell bubbles. However, this method is limited to frequencies below the resonance of the bubble. To achieve enhanced nonlinearity at high frequencies, the oscillations of the UCAs should be optimized. In this work, the Hoff model was solved for a wide range of the parameters of the UCAs. Results showed that when the bubbles are sonicated with a frequency slightly less than the integer multiples of its resonance frequency (e.g., 2.7 and 3.6), and above a pressure threshold (PT), there is a significant increase in the UCA stable radial oscillations, which corresponds to a significant backscattered signal enhancement. If the sonication frequency of the AM technique is optimized according to the mentioned frequencies, and the amplitudes of the AM first and second pulses are smaller and greater than this PT, the CTR of the AM technique may be enhanced significantly.
Characterization of cavitation based on autocorrelation of acoustic emissions.
Authors: Gyöngy Miklós , Jensen Carl R.
Published: July 2011

Cavitation is a phenomenon that causes different bioeffects depending on its stability and strength (that is, inertial character). In current thinking, stable cavitation is associated with acoustic emissions at the harmonics, subharmonics, and ultraharmonics of the driving insonation frequency while inertial cavitation is associated with broadband emissions. To assess the validity of these assumptions, cavitation emissions from microbubbles excited at 1 MHz in 3% agar gel were simulated as well as experimentally recorded. The results show that cavitation may occur “stably” (repetitively) without sub-, ultra-, or integer harmonic emissions, highlighting the need for more precise measures of stability that cannot be captured by frequency-based methods, namely, the variances of emission amplitude and phase. The results also show that inertial cavitation need not cause broadband emissions. In contrast to these ambiguities, the autocorrelation of cavitation emissions allows the estimation of amplitude and phase stability, while the first zero-crossing of the auto-correlation is shown to be closely related to the widely-used measure Rmax/R0 of cavitation strength. Therefore, autocorrelation-based cavitation characterization promises to be a more accurate method of inferring cavitation bioeffects than its frequency-based counterpart.
Characterization of polymer ultrasound contrast agents.
Authors: Allen John S. , Anastasiadis Pavlos , Chitnis Parag , Ketterling Jeff
Published: July 2011

Ultrasound contrast agents are encapsulated microbubbles with unique acoustic scattering signatures. Polymer shelled agents have been shown to be advantageous for tissue perfusion studies and also more recently high-frequency ultrasound applications. The thickness and material of the polymer shell can be more finely adjusted for the specific application in the production process. Only recently have independent measurements of the shell material parameters been attempted. We present a series of elastic shell parameter measurements made using two complementary techniques: high-frequency acoustic microscopy and nano-indentation (Hysitron device). The elastic properties of the thin films of the polymer material (Philips agents) were measured using both methods. Also variations of these techniques were applied to the full spherical shells to examine curvature effects. Acoustic microscopy measurements indicate values for acoustic impedance of 1.73 MRayl. Simulations are highlighted. [Work supported by NIH EB006372 and 2G12RR003016121.]
Vibrational response of a simulated 1-3 composite array.
Authors: Hull Andrew , Cray Benjamin
Published: July 2011

The objective of this work was to identify structural waves (and their corresponding parameters) that propagate in plates that consist of periodic elements embedded in filler materials. To this end, wavevector decompositions were made of highly-sampled (in time and space) measurement data, using two different plates, one of which was isotropic and the other fabricated so that its mechanical structure emulates a typical 1-3 composite array plate. Knowledge of the various wave types that propagate and attenuate will reveal the lateral deformation of the elements (sensors) along with the normal stresses and shear stresses that are applied by the filler material onto the sensors. These stresses produce secondary voltages in the sensors which are detrimental to the primary voltage output and thus degrade array performance. A secondary objective therefore will be to determine values of the parameters (e.g., distance between sensors and filler material) that minimize these detrimental effects in the frequency band of the sensor system.
Flow noise of underwater vector sensor embedded in a flexible towed array.
Authors: Korenbaum Vladimir , Tagiltsev Alexander
Published: July 2011

The objective of this work is the simulation of the flow noise of a vector sensor embedded in a flexible towed array. The developed mathematical model, based on long-wave analysis of the inner space of a cylindrical multipole source, predicts essential cancellation of flow noise of a vector sensor embedded in a underwater flexible towed array by means of intensimetric processing (cross-spectral density calculation of responses of oscillating velocity and sound pressure sensors). It is experimentally found that intensimetric processing results in flow noise cancellation by 12–25 dB on mean levels and by 10–30 dB on fluctuations re squared oscillating velocity channel. The effect of flow noise suppression in the intensimetry channel re squared sound pressure channel is observed only for frequencies above a threshold. These suppression values are 10–15 dB on mean noise levels and 3–6 dB on fluctuations. The threshold frequency on fluctuations is between 30 and 45 Hz under towing velocities 1.5–3 ms−1 and accumulation time 98.3 s.
When “keep it simple” turns into dangerous misconceptions: A Brazilian case study.
Authors: Paul Stephan
Published: July 2011

Communicating acoustics to naive subjects by means of the news media requires a good balance between “keep it simple” and correctness. Unfortunately in Brazil, the balance is usually not maintained and “keep it simple” is often even substituted by erratic use of terms and concepts, not only in news media material [Paul, S., Proceedings of the XXIII Encontro da Soc. Brasileira de Acstica (2010)]. The analysis of Brazilian news media material, but also folders, brochures, etc., issued by equipment suppliers, shows terrific errors regarding even simples concepts such as the definition of sound. Unfortunately it can be even shown that erratic use of terms and concepts in news media, brochures, etc., negatively affects the Brazilian legislative, causing erratic noise pollution laws. To change this specific situation in Brazil, a joint effort of the Brazilian acoustics community is required, e.g., on (1) issuing a guide on “communicating acoustics correctly,” (2) introducing a Brazilian standard that defines terms and concepts in acoustics (first proposals made by Souza and Paul: [Ferramentas para uma padronização dos termos utilizados em acxfa;stica e vibrações, Acstica&Vibrações, 42, (2010)], and (3) thorough revision of Brazilian print/online material.
Materials in musical instruments.
Authors: Hansen Uwe J.
Published: July 2011

Materials play an essential role in determining tonal characteristics and tone quality of string and percussion instruments. Their role in wind instruments is a matter of ardent debate among scientists, instrument makers, and performers. For instruments in which the structural elements are primarily responsible for the radiated sound this importance is self-evident. That significance is less obvious for instruments where the structure primarily serves to contain the vibrating air column. A few general concerns will be discussed and specific examples will be given.
The choice of materials for “brass” instruments.
Authors: Pyle Robert
Published: July 2011

It is generally accepted by players and builders of brass instruments that instrument response and timbre are significantly affected by what would appear to an “outsider” to be minor changes in the materials used to construct the instrument. This talk will present the opinions of players and makers as learned through personal interviews and from advertising literature. Particular attention will be paid to the process of refining a trumpet design to tailor the instrument to the wishes of an individual player.
Evolution of music wire and its impact on the development of the piano.
Authors: Giordano N
Published: July 2011

The earliest pianos were strung with brass and iron strings, and the material properties of these strings placed limitations on the design of these instruments. Over time, improvements in technology produced wire with improved tensile strength, which allowed important changes in piano design. This work culminated in the mid-to-late 1800s with the availability of steel music wire, and piano design has changed remarkably little since that time. This talk reviews how and why improvements in music wire influenced the development of the piano and speculates on how further improvements might (or might not) impact piano design. Our analysis will include spectral data from instruments from several different eras.
Prediction of flow induced noise near a rigid body at low Mach numbers.
Authors: Wang Yiping , Chen Jun , Li Kai Ming , Wang Yiping , Gu Zhengqi
Published: July 2011

For low Mach number flow around a solid body, the far-field sound pressure is dominated by dipole sources comparing with the monopole and quadruple components. The dipole sources are created by the unsteady surface pressure distributions due to the presence of a turbulent boundary layer in the vicinity of the solid body. The far-field sound pressure can be calculated by integrating the time derivative of the wall-pressure fluctuations at the surface of the rigid body. Recent development in computational fluid dynamics (CFD) brings a powerful tool for predicting unsteady turbulent flow fields and the generation mechanism of aerodynamic noise. The current study investigates the use of improved CFD method to accurately simulate the flow fields near a solid body. The information of the flow field is then used to calculate the far field sound pressures. Extensive computations have been conducted to calculate the noise induced by the flow over a circular cylinder and an automobile’s rear view mirror. The calculated sound pressure levels have shown to agree well with published experimental results. [Work sponsored by the China Scholarship Council.]
Contribution of non-verbal and non-ventilation noise sources to background noise levels in elementary school classrooms.
Authors: Hornecker Alex , Giacomoni Clothilde , Vigeant Michelle C. , Celmer Robert D.
Published: July 2011

The goal of this project was to determine the effect of hard versus soft flooring on overall speech and activity noise levels in elementary classrooms. Long-term calibrated sound recordings were measured in second and fifth grade classrooms. Within each grade level, two different classrooms were used: one with vinyl composition tile (VCT) flooring and one with short-pile rubber-backed commercial carpeting. The same students circulated between these rooms by grade level, providing a means of comparing sound levels generated by the same population on different floor surfaces. The VCT and carpeted classrooms had similar floor area, layout, and room volume. Recordings were edited to parse the calibrated WAV files into separate segments of (a) teacher/student speech (without other activity) and (b) classroom activity noise including footfalls, chair scrapes, and impacts (no speech). It was found that the type of flooring made a significant difference in measured activity noise. Increased levels found in the VCT classrooms were attributed more to interactive effects with the floor types than to differences in total room acoustic absorption. The third-octave bands where significant activity noise levels occurred varied by age group. Implications for future floor treatments are discussed. [Work supported by Paul S. Veneklasen Research Foundation.]
A portable, real-time vocoder: Technology and preliminary perceptual learning findings.
Authors: Casserly Elizabeth , Pisoni David B. , Smalt Christopher , Talavage Thomas
Published: July 2011

Transformed or vocoded acoustic signals paralleling the processing of cochlear implants have proven extremely useful for simulating aural perception in deaf CI users with normal hearing participants. The benefits of current perceptual studies with vocoded stimuli are limited, however, in their ecological validity and direct applicability to the everyday challenges faced by CI users. Normal hearing subjects listen for relatively short periods of time to isolated, prerecorded words or sentences; therefore, their perceptual learning occurs without the semantic context, visual support, and conversational interplay that normally accompanies spoken language use. In this paper, the development of a new device, which enables vocoded speech research to overcome many of these limitations, is described. This technology carries out vocoding signal transformations in real-time, with very short delays, and is small enough to fit in a participant’s pocket. The portable, real-time vocoder (PRTV) therefore allows subjects to experience vocoded acoustics while freely interacting with their environment and the people in it, potentially for extended periods of time. Preliminary investigation of perceptual learning with the PRTV has demonstrated its efficacy: improvements of up to 15% in open-set word recognition accuracy were found in 3 NH listeners after 1.5 h of interactive use.
Comparing voice quality measures from steady-state phonation and continuous speech.
Authors: Gerratt Bruce R. , Kreiman Jody
Published: July 2011

The debate over the equivalence of voice quality measures derived from continuous speech vs steady state vowels is founded in the various definitions of voice quality and the resulting uncertainty about which aspects of speech measures of quality are most important. Measures derived from steady-state phonation correspond to narrow definitions of voice quality as the perceptual consequence of vocal fold vibration. Measures from continuous speech derive from broader conceptions of voice quality as essentially synonymous with speech encompassing articulation, unvoiced portions of utterances, and sentential prosody. To complicate this matter, quality measures from continuous speech may reflect gestures related to linguistic voicing contrasts (e.g., breathiness near /h/). We will argue that measures from continuous speech depend on the measurement of vocal quality within the vowels: Because vowels form the largest voiced portion of continuous speech, any measure of quality must quantify their sound. To assess the perceptual equivalence of continuous speech vs steady-state phonation, we therefore used analysis by synthesis to compare steady-state vowels to vowels extracted from continuous speech, for 20 speakers with vocal pathology. Results will be discussed with respect to the overall manner in which quality should be quantified. [Work supported by NIH.]
Curvature of the medial surfaces of the vocal fold, the surface wave model, and phonation threshold pressure.
Authors: Fulcher Lewis P. , Scherer Ronald C.
Published: July 2011

Focusing on characteristics of waves propagating along the medial surfaces of the vocal folds, Titze derived an analytic formula for the phonation threshold pressure (PTP). Among the relationships made explicit by this formula is that converging glottal shapes should have a higher PTP than diverging glottal shapes, for a given glottal width. Although several aspects of Titze’s formula have found experimental support, measurements of the angle dependence of the PTP [Chan et al., “Further studies of phonation threshold pressure in a physical model of the vocal fold mucosa,” J. Acoust. S. Am. 101, 3722–3727 (1997)] do not follow the expected trend. Introducing the bulge parameter allows one to examine the role of glottal curvature and thus to explore the effects of more realistic prephonatory glottal shapes. Preliminary calculations for the modified rectangular glottis show that the bulge leads to somewhat higher PTP values for larger bulges, but no distinctive qualitative features. The effects of introducing a bulge for the converging and diverging glottal shapes will be also explored for biomechanical parameters appropriate for human phonation and for the model of Chan et al. [Work supported by NIH Grant No. R01DC03577.]
Ultrasound focusing to a predefined area using principles of time reversal acoustics.
Authors: Sutin Alexander , Sinelnikov Yegor , Gandhi Gaurav , Rapoport Natalya , Sarvazyan Armen
Published: July 2011

There are several applications of ultrasound that require accurate ultrasound focusing to a predefined area without affecting the surrounding medium. We present two methods of generating high intensity ultrasound field accurately tailored to the shape of the predefined area using the time reversal acoustics (TRA) principles. The first method is based on TRA focusing to the volume distribution of nonlinear sources—ultrasound contract agents (UCAs) placed to sonicated volume. The second method is based on the sensor measurements of a set of impulse responses from a number of points in the sonicated volume. Impulse responses for some of these points can be measured directly and some of them can be based on mathematical interpolation of the measured points. The suggested methods were modeled and the second was tested in the laboratory experiments and is currently being explored for the ultrasound-assisted treatment of pancreatic adenocarcinoma performed by direct injection of a drug into the tumor. The tip of the injection needle includes an ultrasonic sensor providing measurements of impulse responses required for the formation of the desired focal structure. The suggested approach may be applied for other TRA applications including nondestructive evaluation (NDE) and seismic exploration.
Optimizing time reversal mirrors in a half-space environment with application to localization of jet noise.
Authors: Harker Blaine M. , Anderson Brian E.
Published: July 2011

Time reversal (TR) is a technique of mapping acoustical sources using a time reversal mirror (TRM) and is especially useful in reverberant environments. Studies of using TRMs in chaotic, reverberant environments have shown that the mirror elements should be spaced with no smaller than a half-wavelength spacing [IEEE Trans. Ultrason. Ferroelectr. Freq. Control 39(5), 555–566 (1992)]. In a half-space environment, TR cannot exploit multiple reflections to enhance source localization. Thus the question arose as to whether half-wavelength spacing of TRM elements was optimal or not when using TR in a half space. Using simple point source propagation theoretical computer modeling and experimental measurements, it is shown that the TRM elements need not be spaced as close as a half wavelength to optimize focusing. The purpose of this study is to optimize TR localization of an acoustical source using as few TRM elements as possible, thereby increasing the efficiency of the technique. [This work is supported by the Acoustical Society of America’s 2010 Robert Young Award.]
Using the impulse response from blind deconvolution for elementary source localization.
Authors: Abadi Shima H. , Rouseff Daniel , Dowling David R.
Published: July 2011

Artificial time reversal (ATR) is a technique for blind deconvolution in an unknown multipath environment that relies on generic features of underwater sound propagation. Ray-based ATR uses a beam-former-determined reference-ray arrival direction to construct a frequency-dependent phase correction at the receiving array that allows the source-to-array impulse response of the sound channel and the original source waveform to be separately estimated. Although absolute timing and amplitude information is not recovered by ATR, the relative arrival timing of the various signal propagation paths can be determined from the temporal spacing of peaks in the ATR-determined impulse response. With this relative timing information, elementary source localization may be possible when some environmental information is available at the array, and ray-path arrivals can be separated by beamforming at the array. This presentation describes results from underwater experiments involving source-array ranges of 100–500 m in 60-m-deep water and 50-ms chirp signals with a bandwidth of 1.5–4.0 kHz. The ATR-based localization results are found to be comparable with those from coherent and incoherent Bartlett matched field processing. [Work supported by ONR.]
Array design for matched field processing: Role of extending aperture to two dimensions.
Authors: Hursky Paul , Abawi Ahmad T. , Porter Michael B.
Published: July 2011

Most work on MFP has been done with vertical line arrays, and indeed, using the near-orthogonality of the normal modes over the water column provides better resolution of range and depth than a horizontal array of comparable size. However, when we put an array into an environment where there are multiple sources, some much louder than others, the horizontal aperture’s ability to form nulls in azimuth starts to trump the vertical aperture. We will present simulation results comparing various combinations of horizontal and vertical apertures and evaluate their ability to both resolve source range and depth and to cope with a loud interfering source in an adaptive MFP context, where the loud source hides other sources if conventional Bartlett (i.e., nonadaptive) MFP is used.
Impact sound insulation predictions for light weight floors: Potential modal response of the floor and its effect on impedance.
Authors: Griffin D.J.
Published: July 2011

While light weight flooring systems are commonly used in new apartment developments in many countries, they are generally regarded as providing only moderate impact sound insulation. Poor acoustic design of a light weight flooring system can result in non-compliance with applicable building code standards and poor perceived performance, particularly in comparison to massive floor systems which include a concrete slab. It is therefore useful to develop a reliable prediction routine, to engineering accuracy, for light weight floors. This paper briefly outlines existing theory for prediction of impact sound insulation for light weight floors. A development of the basic model is proposed, involving consideration of the modal response of the floor membrane and its potential effect on the impedance of the floor in the mid-frequency region.
Singing wine glasses and whistling bottles.
Authors: Philip Trudy L.
Published: July 2011

These are two experiments that are easy to do at home. The first is with a wine glass, it does not have to be fancy, but it must be a glass on a stem. Put some water in the glass and hold the glass firmly on the counter by the stem. Wet one of your fingers and run it around the rim of the glass. Eventually, the glass will sing. Change the amount of water in the glass, the pitch will change. A bottle is needed for the second experiment. It does not have to be a specific type of bottle or a certain height, it does not even need to be glass; however, it may be easiest with a bottle with a narrow neck and smaller opening like a soda bottle. With about half the bottle full of water, blow across the top of the opening of the bottle, trying not to blow directly into the bottle. You may have to adjust the angle at which you are blowing, but eventually the bottle will whistle. Now, change the amount of water in the bottle and the pitch will change. These singing household items use two different acoustic principles!
Hot topics of signal processing in acoustics.
Authors: Chambers David H.
Published: July 2011

Signal processing is used to some extent in all areas of acoustics such as extracting relevant information from acoustic measurements made either in the laboratory or in the field, processing signals, and/or synthesizing data to cope with demanding tasks raised in acoustics. Techniques range from simple classical approaches based on Fourier transforms and Gaussian noise to sophisticated model-based techniques that incorporate physical/parametric models of the acoustical system. In this talk we highlight new approaches to signal processing that could be applied to a broad variety of acoustical problems. Examples of each approach will be shown to illustrate the class of problems addressed and the performance. [This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.]
Environmental noise study and follow-up measurements at the White River Amphitheatre in Auburn, Washington.
Authors: Park Ioana , Hesedahl Jeanette
Published: July 2011

The 20 000-seat White River Amphitheatre is located in Auburn, WA, approximately 35 miles southeast of Seattle. Built by the Muckleshoot Indian Tribe on reservation property, the project was not subject to jurisdictional noise limits during the permitting phase. However, after the basic structure and roof of the amphitheater were standing, the tribe learned of the Environmental Impact Statement requirement. Utilizing noise limit requirements from the two neighboring Washington State counties, criteria for identifying and evaluating noise impacts were developed for the study purposes. Original source level measurements from Shoreline Amphitheatre in Mount View, CA were reconciled with modeling results to produce sound level contours and predictions for sound levels in the 63-Hz and 125-Hz octave bands. Noise mitigation measures included constructing rear and side walls to the performance and audience area, installation of acoustically absorptive material to the underside of the roof structure, and separate directional time-delayed speakers for lawn seating coverage. This presentation summarizes the modeling process and results, noise mitigation measures employed, design challenges, and sound level monitoring results from the fully operational venue.
Locating a new outdoor performance venue amidst public concern and the resulting sound level impacts at the remote amphitheater site.
Authors: Pettyjohn Steven D.
Published: July 2011

An existing small amphitheater was to be enlarged from its 7000 audience size to hold up to 22 000 people. A threatened law suit by the City of Sacramento forced the developer, Bill Graham Presents, to find another site. Several sites were reviewed and a location on the edge of Folsom was first selected then abandoned when many people showed up to protest. The final site selection for the amphitheater was in a remote, rural area where the land was zoned for agricultural use. The surrounding land is used for growing rice and for pasture land for cattle operations. The County has jurisdiction over the land and has very poor noise regulations and a tendency to not enforce what they have. One rancher living north of the amphitheater filed a law suit against the operation of the facility because of deleterious impacts on both her well being and her cows. Sound measurements were made during a single concert representing a hard rock band to quantify the sound levels and the tonal content of the sound during normal operations. This paper provides the history of this process and the results from the sound tests done at the site.
Supersonic flows and their interaction with propagating acoustic signals: Acoustic black holes in the laboratory.
Authors: Goldstein David J. , Orris Gregory J. , Szymczak William G.
Published: July 2011

Work in particle physics and general relativity (GR) has established that deep connections exist between acoustics and GR. Most remarkable is the fact that acoustic wave propagation in fluids is governed by an effective Lorentzian spacetime geometry: Acoustic waves follow the geodesics of a (curved) acoustic metric. This provides an entirely new way of looking at acoustic propagation, and in principle provides valuable theoretical tools since much of the machinery developed by the GR community over the past several decades can be directly applied to acoustic systems expressed in this framework. Notably, supersonic liquid flows are predicted to have completely analogous properties to spacetime regions near (gravitational) black holes. We present the status of a developing research program at NRL, designed to begin exploring these connections via laboratory experiments, numerical simulations, and theoretical development. [Work supported by the Office of Naval Research.]
Coupling layer corrections in pulse echo time-of-flight measurements in solids revisited.
Authors: Sturtevant Blake T. , Pantea Cristian , Sinha Dipen N.
Published: July 2011

It is well known that to extract highly accurate phase velocities from pulse echo ultrasonic time-of-flight measurements, one must take into account the influence of the medium used to acoustically couple the transducer (or buffer rod) to the sample being measured. This correction is typically on the order of 0.1% and is usually achieved by fitting experimental data to a scalar transmission line model in which echoes undergo phase shifts upon transmission through or reflection from the various boundaries. Fitting data to such a model involves varying two free parameters, the thickness of the coupling bond layer and the speed of sound in the sample. When performing the fit, one must make a choice between multiple solutions corresponding to different bond lengths and sample sound speeds. This talk will quantify the importance of the couplant correction in selected cases and discuss the error introduced to the extracted velocities by selecting a “wrong” fit to the data. Additionally, criteria and methods for choosing the “correct fit” without making independent measurements of the bond length will be discussed. [Support for this work was provided by the U.S. DOE.]