bluuebunny/crossref_metadata_2025 huggingface dataset:
Manipulation of fluid objects using acoustic radiation pressure: Beyond drops and bubbles and retrospection
Authors: Thiessen D. B. , Lonzaga J. B. , Osterhourdt C. F. , Wei W. , Marston P. L.
Published: October 2013

Some standard applications of acoustic radiation pressure include the manipulation of drops and bubbles for the study of interfacial dynamics and light scattering. After a review, this presentation summarizes recent applications including radiation pressure effects on small flames and liquid cylinders [Wei et al., J. Acoust. Soc. Am. 116, 201–208 (2004)]. The dependence of the radiation pressure on the acoustic frequency has important consequences including liquid cylinder stabilization. While the radiation pressure is normally associated with sound propagation in the outer gas or liquid, our recent experiments also show that interfacial responses to modulated radiation pressure can be significant when the sound is applied internally to the manipulated object. For example, a liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. When modulated ultrasound is applied to the jet supply liquid with the ultrasonic carrier frequency near-to or above the cutoff frequency, the jet can be made to oscillate at the modulation frequency of the radiation pressure, thus stimulating jet breakup. [Work supported by NASA.]
An investigation of the effect of sound field distribution on the stability of the levitated object in the near-field acoustic levitation
Authors: Kim Cheol-Ho , Ih Jeong-Guon , Lee Sung-Il
Published: October 2013

Near-field acoustic levitation (NFAL) is a method that levitates an object or group of particles using the ultrasonic force. It is observed that, when a circular piston type of source is employed, stability problems can occur which makes the object position unpredictable. For example, a thin, circular planar object wobbles to lateral direction like a pendulum when its center is not precisely coincident with the center of source. In this study, the motive force, which makes the levitated object swivel through the center of source, is investigated by varying the sizes of the object and the source. To this end, a visualization of the sound field in the micro gap between the levitated object and source is made by using a photo view of the motion of fine powder scattered inside. The result is compared with the calculation result by BEM. A further investigation is experimentally made on any relation between the temperature distribution on the surface of the levitated object and the acoustic force. The experimental visualizations and numerical modeling results suggest that one may have a model describing the instability of the levitated object in NFAL, if a proper simplified mathematical model is set up in the further study.
Revisiting the quartic model for early identification of noise-induced hearing loss
Authors: Murphy William J. , Franks John R.
Published: October 2013

In a 1976 article by Cooper and Owen [‘‘Audiologic profile of noise induced hearing loss,’’ Arch. Otolaryngol. 102, 148–150 (1976)], they advanced a quartic model to perform a least-squares fit to an audiogram for the purpose of identifying a noise-induced notch indicative of early onset of noise-induced hearing loss. This model has been revisited for the purpose of better quantification of a set of rules that will best identify the presence or absence of a noise notch. A subset of 1660 subjects’ right and left audiograms collected for the National Health and Nutrition Examination Survey (NHANES IV) was fit with a quartic model. As well, several hearing scientists and audiologists within NIOSH examined and classified the audiograms as having a notch or not. Preliminary results suggest that the choice of notch criteria dramatically affects the identification accuracy when correlated with clinical judgments. This paper will present how these rules were developed and how the quartic model may be interpreted and applied in a hearing conservation program.
Early indicators of noise-induced hearing loss: Issues for consideration
Authors: Stephenson Mark R. , Murphy William J. , Franks John R.
Published: October 2013

A recent article in the NHCA Spectrum [Dobie and Rabinowitz, 20, 8–11 (2003)] considered several methods for identifying the early onset of noise-induced hearing loss (NIHL). Among the methods they examined was the Notch Index: the difference in the pure-tone average of 2, 3, and 4 kHz and the pure-tone average of 1 and 8 kHz. This statistic was expected to be positive for NIHL where noise has produced a threshold shift in the 2- to 4-kHz region but not adversely affected the thresholds at 1 and 8 kHz. The Notch Index was examined for a subset of 1660 subjects’ right and left audiograms collected for the National Health and Nutrition Examination Survey (NHANES IV). The Notch Index did not prove to be effective as expected. However, modifications to the calculation, the inclusion of 6 kHz, or calculation of the area difference provided better identification of the early onset of NIHL. This paper will examine other issues such as work-relatedness and potential gender effects that might be influenced by differential trends in ear canal size.
Relating the acoustic vowel space to perceptual vowel space in cochlear implant simulation
Authors: Liu Chuping , Fu Qian-Jie , Fu Qian-JIe
Published: October 2013

Because of limited spectral resolution, the acoustic differences between important speech features may not be preserved by cochlear implants (CIs). The present study compared the acoustic vowel space of spectrally degraded speech with the perceptual vowel space of normal-hearing (NH) subjects to CI simulations in which the spectral resolution, frequency allocation, carrier bands (noise-band or sine-wave) and signal-to-noise ratios (SNRs) were varied. For each speech-processing condition, acoustic differences between vowel tokens were calculated by extracting the mel-frequency cepstrum coefficients, time-aligning the tokens, then computing the weighted Euclidean distances. Results showed that the acoustic vowel space monotonically expanded with increasing SNR and spectral resolution; sine-wave carriers also expanded the acoustic vowel space, relative to noise-band carriers, for all SNR conditions. We will compare the acoustic vowel space to NH subjects’ perceptual data for these speech-processing conditions. [Research is supported by NIDCD R01-DC-004993.]
Comparison of acoustic features of time-compressed and natural speech
Authors: Kusumoto Akiko , Vaughan Nancy
Published: October 2013

Time-compressed speech is used as a speech material to examine the upper limits of processing speed in young and old listeners with and without hearing loss. Generally, older normal-hearing listeners at 60% time compression perform similarly to younger normal-hearing listeners at 70% time compression on speech recognition test. This may be due to slowing of processing speed that typically accompanies aging. It has not been determined if time-compressed speech material carries spectral distortions or other acoustic changes that affect the ability to process rapidly. If so, differences in performance between younger and older listeners may be attributable in part to acoustic distortions other than temporal changes. In this work, we examine acoustic feature changes in time-compressed speech processed using synchronized overlap-add (SOLA) method. Also, we discuss which parts of speech (consonants or vowels) are more affected by time compression. In the temporal domain, we compare the duration of consonants, vowels and voice onset times (VOT) in both 50% compressed speech and natural speech. We also examine the long-term power spectra of both signals. Possible effects on speech intelligibility will be discussed.
Effects of short-term training on the recognition of spectrally shifted vowels by non-native listeners
Authors: Li Tianhao , Fu Qianjie , Nogaki Geri
Published: October 2013

Previous studies have shown that normal-hearing (NH) native listeners can rapidly adapt (though not always completely) to spectrally mismatched speech with short-term training. However, it is unclear how short-term training might affect the performance of non-native listeners. The present study investigated whether non-native listeners’ recognition of spectrally shifted English vowels could be improved by moderate short-term training. Recognition of 12 American English vowels (in c/V/c format) was trained and tested in five Chinese-speaking NH subjects; speech tokens were processed by an eight-channel noise-band vocoder in which the spectrum was upwardly shifted by one octave. After baseline testing subjects were trained with shifted speech for 5 consecutive days; daily training consisted of three to four sessions, each of which included a 5-min preview of the test tokens and a 10-min test. Results showed that for all subjects, recognition of spectrally shifted English vowels improved significantly over the 5-day training period. These results show that non-native listeners are able to rapidly adapt to spectrally mismatched speech with short-term training. The ability to fully accommodate spectrally shifted speech may depend on non-native listeners experience with the second language. [Research supported by NIDCD R01-DC-04993.]
The sweet spot of a hollow baseball or softball bat
Authors: Russell Daniel
Published: October 2013

The ‘‘sweet spot’’ of a baseball bat is often defined as a region approximately 5–7 in. from the barrel end of the bat where the performance (as measured by a batted-ball speed) is the greatest and the vibrational sensation (the sting felt in the hands) is minimized. In terms of the vibrational properties of a bat, the sweet spot region includes the nodes of the first two bending vibrational modes and is often also identified as being related to the center-of-percussion (COP). This paper will discuss recent research which shows that the COP has no bearing on performance and little, if any, on the perception of feel. We will also discuss the contribution of the bending vibrational modes to the location of the sweet spot and compare results for a wide variety of wood, metal and composite baseball and softball bats. We will attempt to correlate the sweet spot defined in terms of performance and that defined in terms of vibrational sensation. Finally, we will discuss the contribution of the hoop mode, unique to hollow bats, which correlates strongly to performance, and which may also influence the perception of feel.
Bridging the gap between speech research and L2 pedagogy
Authors: Munro Murray J.
Published: October 2013

In studies of L2 speech learning it is common to draw conclusions (sometimes as an afterthought) about the potential pedagogical value of research findings, particularly when they provide insights into specific pronunciation difficulties faced by L2 learners or when they indicate improved perception or production as a result of laboratory training. However, many important research findings have, as yet, had only a minor impact on second language teaching, and there remains a significant gap between what has been empirically established in the research laboratory and what is actually practiced in the classroom. This presentation will identify some of the reasons for this disparity through an examination of goals and priorities that are commonly accepted by pedagogical specialists. In particular, it will be argued that the implementation of research findings depends on establishing practical ways of improving L2 learners’ speech intelligibility (as opposed to mere accent reduction) for a diverse audience of interlocutors in authentic interactive settings. In general, there is a need for research that is specifically motivated by pedagogical concerns and that is informed by an awareness of a wide range of current issues in applied linguistics. [Research supported by SSHRC.]
α, β, and wave-field statistics
Authors: Brown Michael G. , Beron-Vera Francisco J. , Rypina Irina , Udovydchenkov Ilya A.
Published: October 2013

Recent analysis of measurements made in the AET experiment, in which 75±15 Hz signals propagated a distance of 3.25 Mm in the eastern North Pacific Ocean, show that long-held assumptions and theoretical ideas about wave-field statistics at long range require significant revision. Progress towards developing a new theory is discussed in this talk. In contrast to the older theoretical ideas, the background sound-speed structure plays an active and critically important role in the new theory, while details of the perturbation field play only a minor role. The importance of the background sound-speed structure is quantified by the ray-based stability parameter α, or the asymptotically equivalent mode-based waveguide invariant β. [Work supported by ONR and NSF.]
A case study: School band and practice rooms in Harrington Park (NJ) school
Authors: Raichel Daniel R.
Published: October 2013

Several years ago, the Harrington Park (NJ) Board of Education constructed a new gym/cafeteria addition and converted the old multipurpose room in the elementary school (K–8) into a band practice room with two adjacent individual practice rooms. In an attempt to allay the sound level of the band, which can reach as high as 102 dB(A), sound panels having an effective absorption coefficient of 0.74 were installed over approximately 20% of the plaster wall surfaces, resulting in little acoustic effect. An analysis indicates that using wall and ceiling panels with a higher values of absorption coefficients over the entire wall surface and the ceiling would bring the sound level down by only 3 dB, insufficient to bring the prevailing SPLs to more reasonable levels, due to the band’s sound power. However, the reverberation time of 0.8 s would be reduced to 0.3 s, which would allow the music to be more discernible. The walls and the doors separating the individual practice rooms from the band room proved to be ineffective in isolating these rooms acoustically. It was recommended that modular practice rooms be purchased and installed within these two practice rooms, with ventilation ducts leading outside the music complex.
Acoustics in a high school library
Authors: Beristain Sergio
Published: October 2013

A new and up-to-date library is under development within a Mexican high school educational institution. Usually, libraries are supposed to be quiet places where people can read without disturbance, but nowadays with the new data storage technologies and their capabilities for storing much more than only text, where people can interact with the material under study, for instance, read the description of the words Water Fall, see the water sparkling, and hear the sound of the fall, plus the sound of the computers and proyection equipment, libraries tend to be more and more noisy. The approach taken for this project includes separate areas and acoustic absorption material distribution for different activities within the library, such as reading, computer consultation of texts, and computing consultation of multimedia stored books either in DVD format or by the network.
Application of intelligibility metrics to privacy measurements
Authors: McManus Steven
Published: October 2013

The scale of perceived intelligibility runs from the easily understood, down through hard to understand, to private, and finally confidential. When attempting to use STI to measure privacy, it is found that the currently published translations to Articulation Index and therefore Privacy Index do not correlate well with subjective experience at the lower end of the scale. The transition from privacy, where the aim is not to be disturbed, and confidentiality, where the aim is not to be able to eavesdrop, is very rapid. Here, a study is presented that proposes a new mapping from STI to AI and therefore PI, in the low intelligibility range using the accepted threshold of 95% PI as the boundary for confidentiality. This new mapping deviates from the mathematical relationship between STI and AI, which is based solely on signal to noise ratio.
Detection of a unique calling pattern during the respiratory cycle of blue whale pairs
Authors: Berchok Catherine , Bradley David , Gabrielson Thomas , Sears Richard
Published: October 2013

Although blue whales are known for their long (10–20 s) low-frequency (<20 Hz) vocalizations that occur in regularly patterned series, in coastal waters they produce short (1–4 s) higher-frequency (30–150 Hz) unpatterned calls just as often. Paul Thompson was among the group of scientists who first attributed these short calls to blue whales. They found the majority of these calls to be downswept in frequency but noted the presence of others that were not. This paper describes a special patterning of these non-downswept sounds that was detected in the St. Lawrence estuary in both 2000 and 2001. This patterning is variable but normally includes both regularly and irregularly spaced components. In at least a dozen cases, these mixed-pattern bouts were detected in the presence of a pair of blue whales at the surface for their respiratory cycle. Characterization of these bouts and their daily, seasonal, and spatial distributions will be presented and compared with the distributions of the short downsweeps and the long low-frequency calls. [Work supported by the Applied Research Lab (Penn State), NSF, and the American Museum of Natural History.]
Source levels of free-ranging killer whale (orcinus orca) social vocalizations
Authors: Veirs Val
Published: October 2013

An array of four hydrophones spaced over 200 m near the shore of San Juan Island, WA, has been used to localize the underwater vocalizations of Southern Resident orca whales. The hydrophones (ITC) have home-built pre-amps and amplifiers and signals are digitized simultaneously by two computers. The system has been calibrated with an underwater speaker (J-9). Automatic call detection is used to activate data logging on one computer and real-time localization on a second that directs a video camera to record the water’s surface at the predicted source location. The system requires about 1 s to detect a call, locate it and redirect the video camera. This is the first report of source levels of social vocalizations of free-ranging Southern Resident orcas. To date (July 2004), 160 orca calls have been localized within 200 m of the center of the array. The average acoustic intensity of these calls is 145 dB re 1 μPa@1 m. The range of intensities is from 137 to 157 dB re 1 μPa@1 m. Complete results including intensity angular distributions with respect to the probable direction of whale travel will be presented. [Work supported by 32 undergraduate researchers over 5 years and the Colorado College Physics Department.]
Acoustical nonlinearities in compression chambers and horns of horn drivers
Authors: Voishvillo Alexander
Published: October 2013

A horn driver is an essential part of sound reinforcement systems. Principles of horn driver operation are associated with generation of acoustical nonlinear distortion. Distortion is generated in a compression chamber by nonlinear compression, and by modulation of air stiffness, mass, and viscous losses, and a nonlinear relationship between particle velocity and sound pressure. Distortion is also generated in the phasing plug and horn by propagation of high amplitude waves. The effect of compression chamber air mass and viscous losses modulation and nonlinearity has not been researched previously. The analysis of modulation and nonlinear effects in the compression chamber is based on analysis of variation of the compression chamber’s air moving mass, viscous losses, and compliance as a function of the diaphragm’s instantaneous position and level of acoustical pressure. The pressure and diaphragm position-dependent parameters are incorporated into the system of nonlinear differential equations governing movement of the diaphragm and oscillation of air in compression chamber. Analysis of nonlinear propagation effects in the phasing plug and horn is based on numerical solution of an implicit nonlinear equation for propagation of finite amplitude sound waves. The work results in the methodology of simulation dynamic performance of horn drivers and provides comparative analysis of different acoustical nonlinear and parametric mechanisms.
Expressive modeling of Chinese folk wind instruments
Authors: Ayers Lydia , Horner Andrew
Published: October 2013

Chinese folk wind instruments, including the paixiao, xun, koudi, bawu, hulusi, and lusheng, have distinctive timbres but are less well known than the other Chinese wind instruments. The paixiao (a panpipe) and the xun (ocarina) are ancient instruments. The koudi is a small bamboo whistle/flute, which can play exciting birdlike melodies. The bawu, hulusi, and lusheng have different shapes and playing techniques but have similar embedded metal plate reeds that produce their sounds. This talk will give brief descriptions of the musical and spectral characteristics of these instruments, and then describe the additive synthesis design template used to capture their subtle timbral characteristics using score data in Csound. In addition, the design is expressive and successfully uses spectral interpolation for the idiomatic ornamental phrasing for each instrument. We use a special amplitude/frequency function modulation method to simulate trills, which are also tied to varying numbers of grace notes, as tested on traditional Chinese scores. [Work supported by RGC Grant No. HKUST 6020/02H, with special thanks to Chan Chun Nin for recording instrument samples and consultation on playing the instruments, and to Alfred Wong and Jenny Lim for preparing examples.]
Conch-shell and bamboo flute: Spiritual and musical expressions of acoustics in Vedic Hinduism
Authors: Prasad M. G.
Published: October 2013

In Vedic Hinduism rooted in India, the field of acoustics plays an important role. The multi-faceted expressions of acoustics include Vedic mantras (chants), music, yoga, philosophical aspects of language, spiritual aspects of sound, etc. A large number of musical instruments such as woodwind, percussion, string, etc. are used in Hindu culture and religion. Conch-shell and bamboo flute are among the earliest musical instruments. A conch-shell is used to evoke the spiritual effects in the environment during worship rituals at temples and homes. It has a high quality factor. The music played through a transverse bamboo flute is very melodious. It is a major instrument in orchestra music and dance performance. Concerts with bamboo flute as the lead instrument are also very common. This paper deals with spectral characteristics and tonal effects of these two important instruments. Also, the presentation includes a discussion of the importance of acoustics in life as viewed in Vedic Hinduism.
Model experiments on the ‘‘sawari’’ mechanism: Vibrational behavior of a string with a moving boundary
Authors: Fujise Akiko , Yoshikawa Shigeru
Published: October 2013

The ‘‘sawari’’ mechanism, seen in some plucked string instruments like Japanese biwa and shamisen, produces the vibration of the string with a moving boundary and results in its unique sustaining tone, whose elaborate tuning is essential in Japanese traditional music. Since a slight change of the sawari surface’s shape strongly affects the tone quality, it is important to examine the relationship between the boundary shape and the consequent vibration in reality. In this presentation, some results of model experiments on a string with the sawari mechanism are reported and discussed. By using a high-speed digital video camera and a piezo-electric pickup, the overall string motion and the local interaction between the string and the boundary surface are experimentally measured under several sawari conditions. The results are analyzed by applying image processing to video data and also time-frequency analysis to acceleration signals, then compared between basic shapes (plain and curved), widths, and shaven depths of the constraint.
Towards aural opacity—across a visually transparent medium
Authors: Ermann Michael , Lutz Matt , Jackson Chris , Karius Brooke , Kilper David , Kunjara Na Ayudhya Indhava , Pettin Thomas , Pritts Tom , Seitz Damian , Stuecker Rebecca , McCoy Joe
Published: October 2013

Virginia Tech students undertook a study and participated in a design competition to provide the campus physical plant building with a wall that allows for natural light and views while maintaining a suitable aural barrier. The wall, which replaces a large garage door, will be constructed as part of an effort to renovate a wood/metal shop into an office. It must provide for adequate transmission loss to account for the noise generated by adjacent utility trucks, shop activities and an ad hoc basketball court. Unable to obtain published data for glass vestibules, students measured the transmission loss across another campus building’s glass entry vestibule. Currently there are plans for the winning students design entry to be constructed as part of the renovation.
Sound, as we see it—A better way to diagnose noise sources
Authors: Beniwal Ravinder , Wu Sean
Published: October 2013

In the noise control community, it is often required to diagnose noise sources and their transmission paths. Usually, noise diagnosis consists of taking sound pressure, power, and intensity measurements around suspected sources to learn noise characteristics. If these are not enough to pinpoint the sources, then source ranking and identification of contributions from individual components are carried out. Naturally, success in this type of diagnostics requires many years of practical experiences. Even so, these tests are time consuming and ad hoc in nature, and the results thus obtained are valid at measurement locations only. In this paper, a new approach to noise diagnostics is presented, which can significantly reduce the time and complexities involved in diagnostics. This approach is based on the Helmholtz equation least-squares method to visualize the entire sound field generated by a sound source. It allows for 3D conformal measurements of the acoustic pressure and produces an accurate mapping of the acoustic field on 3D surfaces and surrounding medium. These results enable one to trace sound back to its source and separate airborne from structure-borne sounds. The process can be completed in minutes and the acoustic images thus obtained speak for themselves. [Work supported by NSF.]
Reconstructing transient acoustic field resulting from an explosion
Authors: Lu Huancai , Wu Sean
Published: October 2013

Generalized Helmholtz equation least squares (HELS) formulations for reconstructing transient acoustic radiation from an arbitrary object subject to arbitrarily time-dependent excitations are developed. Laplace transform is employed to build a transfer matrix for a multi-input multi-output system and reconstructed signals are obtained using convolution with respect to the input data in the time domain directly. Stability of solutions is realized by controlling the pole-residue locations in the Laplace domain. To facilitate calculations of the poles and residues, ztransform is utilized. To validate this general transient HELS formulation, the reconstructed pressure histories are compared with those measured by pressure sensors at the same locations. Space-time tomography resulting from different charges is produced, and the acoustic pressure distribution over the entire time record is reconstructed. It is interesting to notice that this transient HELS formulation enables one to trace time histories of blast pressures back to the explosion location. In other words, it is possible to reconstruct an explosion back in space and time based on the time-domain signals measured at a later time. [Work supported by NSF.]
Method of superposition applied to patch holography
Authors: Sarkissian Angie
Published: October 2013

The method of superposition is applied to reconstruct the field on a patch on the surface of a radiating structure from measurements made on a nearby surface. In patch holography the measurement surface need not surround the entire structure. It need only be approximately as large as the patch on the structure surface where the reconstruction is required. The surfaces may be planar or curved. The method of superposition is applied where the field on and near the measurement surface is approximated by the field produced by a large number of sources placed on a nearby surface inside the radiating structure. The source strengths are determined by applying boundary conditions on the measurement surface. Because of the ill-posed nature of the problem, this procedure requires the inversion of an ill-conditioned matrix. Singular value decomposition is applied to invert it. Once the source strengths are determined, the field on the partial structure surface may be approximated by the field produced by the sources. [Work supported by ONR.]
Active vibration damping for optical tables
Authors: Ryaboy Vyacheslav
Published: October 2013

The paper considers theoretical background, analysis and experimental verification of an active vibration damping system for optical tables. Optical table is a generic name for a stiff platform supporting vibration-sensitive equipment. A typical optical table is a sandwich structure consisting of two faceplates and a lightweight (usually honeycomb) core. Due to low weight-to-stiffness ratio, these platforms found wide application in optical research and high-precision manufacturing, usually in conjunction with soft pneumatic vibration isolators. Although excellent isolation from floor vibration can be achieved in these systems, the platform deviates from the ideal rigid-body behavior at natural frequencies of its flexural vibrations. The theoretical analysis and experimental data reported in this paper show that a properly designed active damping system consisting of a small number of collocated sensor-actuator pairs provides robust and universal means of attenuating these unwanted vibrations.
The production of the stop voicing distinction in French at normal and rapid speaking rates
Authors: Abdelli-Beruh Nassima
Published: October 2013

This study examined how monolingual Parisian French speakers produced the stop voicing distinction at two different speaking rates (normal, rapid) in two different phonetic contexts (between vowels, between voiceless-fricatives). Results showed that all the acoustic correlates of the voicing distinction under study (syllable-initial: VOT, closure duration and closure voicing; syllable final stops: preceding vowel duration, closure duration, closure voicing and release) were shorter in the rapid speaking rate condition than in the normal speaking rate condition. Furthermore, voicing-related differences were also smaller in the rapid speaking rate condition than in the normal speaking rate condition to a degree that varied with each acoustic correlate and each phonetic context. Overall, similar patterns of voicing-related duration differences and closure voicing differences were found in the normal and rapid speaking rate conditions, but the perceptual salience of small voicing-conditioned duration differences remains to be investigated.
A cross-language study of the influence of duration and intensity on perception of lexical stress
Authors: Moran Cheryl L. , Coren Amy E. , Hay Jessica F. , Diehl Randy L.
Published: October 2013

The present study examines perceived lexical stress across five languages which differ in their prosodic characteristics: English, French, German, Japanese, and Turkish. Native speakers from each language were presented with a two-syllable nonsense word, (/bibi/), and were asked to judge whether the first or second syllable was more prominent. The relative durations and intensities of the two syllables were varied orthogonally across ranges, which were determined on the basis of analyses of natural utterances from the five languages. The key issue addressed is whether judgment of syllable prominence is cross-linguistically invariant or dependent on exposure to language-specific lexical stress patterns. [Work supported by NIDCD.]
Envelope offset asynchrony as a cue to voicing in final english consonants
Authors: Yuan Hanfeng , Reed Charlotte M. , Durlach Nathaniel I.
Published: October 2013

Previous research [Yuan et al., J. Acoust. Soc. Am. 113, 2291 (2003)] has demonstrated that a simply derived, real-time measurement of the envelope-onset asynchrony (EOA) of two different bands of speech serves as a reliable cue to syllable-initial voicing. The current study was undertaken to determine the applicability of a similar type of temporal cue to voicing of final consonants. This cue is based on the time asynchrony between the offsets of amplitude-envelope signals derived from two different bands of speech (a low-pass-filtered band at 350 Hz and a high-pass-filtered band at 3000 Hz). Measurements of the offset-timing difference between the low- and high-frequency envelopes (EOFA) were obtained on a set of 16 final consonants represented through multiple tokens of C1VC2 syllables. The EOFA measurements were fit to Gaussian distributions and signal-detection theory was applied to determine the discriminability of pairs of voiced–voiceless cognates by an ideal observer. These results indicate that the EOFA cue provides a reliable and robust cue for distinguishing voicing in syllable-final position regardless of manner or place of production. This cue has applications to the design of sensory aids for the deaf as well as to automatic speech recognition. [Research supported by NIDCD Grant R01-DC00126.]
Video/acoustic-array studies of swarming by echolocating bats
Authors: Simmons James A. , Eastman Kyler M. , Auger Gregory , O’Farrell Michael J. , Grinnell Alan D. , Griffin Donald R.
Published: October 2013

Echolocating bats (Pipistrellus, Myotis) sometimes fly in dense swarms for 1–2 h over desert water sources. Swarming is different from streaming at caves or roosts because ∼10–100 bats staying within a small volume (∼1000 m3) for an extended time rather than transiting. We study swarming using thermal infrared video cameras and a three-microphone acoustic array. Swarming bats emit a steady stream of short (∼2 ms) FM sonar sounds with nearly identical sweeps and a collective duty-cycle approaching 100%. Surprisingly, given the tendency to think in terms of bats in close proximity deliberately varying their signals for jamming avoidance, the signals of swarming bats are very similar. Video/acoustic tracks reveal no sign of mutual interference or collisions. It is not obvious whether bats gather to drink or to feed on insects, which also congregate near the water, or whether social behavior predominates. Some drinking occurs throughout the swarming period, but the occurrence of captures during swarming is negligible, at least judging from the absence of feeding buzzes. The bats may use multistatic sonar, in which each bat takes advantage of the sounds of other bats as helpful additional ensonification rather than interference. [Work supported by NIMH, DoD, Brown University.]
A generalized Cramer–Rao lower bound for line arrays
Authors: Sullivan E. J. , Edelson G. S.
Published: October 2013

The Cramer–Rao lower bound (CRLB) on the variance of an estimate is a consequence of the underlying likelihood function. That is to say, the more realistic the likelihood function, the more realistic the bound. It is shown here that by including the forward motion of a line array in the likelihood function for the bearing of a continuous broadband signal, the CRLB on the bearing estimate is lower than that found for the case of the stationary array. This is a consequence of the fact that there is bearing information contained in the Doppler that is not exploited by conventional beamformers. Further, it is shown that this improvement in performance requires that a nuisance parameter in the form of a source frequency be jointly estimated along with the bearing. An example is given which uses a recursive processor and a synthetic broadband signal from a nonmoving source. It is shown that the performance improvement relative to a stationary array of equal physical aperture is a function of the array speed, the integration time, the bearing angle and the direction of motion of the array, i.e., whether the motion incurs ‘‘up’’ or ‘‘down’’ Doppler.
6+ years of acoustic thermometry in the North Pacific Ocean: A cycle of the Pacific decadal oscillation
Authors: Dushaw Brian D. ,   the NPAL Group
Published: October 2013

Acoust. measurements of basin-averaged temperatures have been made in the North Pacific over the last 8 years. The acoustic observations give integral measurements of ocean temperature with the averaging needed to detect weak, gyre-scale signals out of the dominant mesoscale variability. An acoustic source on Pioneer Seamount off California transmitted to receivers distributed throughout the North Pacific from 1996 to 1999 as part of the Acoust. Thermometry of Ocean Climate (ATOC) project. A second source, located near Kauai, began transmitting in 1997. The Kauai acoustic transmissions are part of the North Pacific Acoust. Lab. (NPAL) project. A 6-year time series has been obtained with sampling six times per day every 4 days. The cabled-to-shore source and receivers provide near real-time data. Long-period changes in temperature are apparent in the time series from the Kauai source. The paths from Kauai toward the California coast show steady cooling. A path to the northwest showed warming until early 2003, when the ‘‘normal’’ annual cycle returned. Comparisons of the acoustic data to observations by altimetry and Argo floats are not definitive because of the great differences between data types. (J. Colosi, WHOI; B. Cornuelle, SIO; B. Dushaw, APL-UW; M. Dzieciuch, SIO; B. Howe, APL-UW; J. Mercer, APL-UW; R. Spindel, APL-UW; P. Worcester, SIO)
Sensitivity kernels for finite-frequency ocean acoustic observables
Authors: Vera Michael , Skarsoulis Emmanuel K. , Cornuelle Bruce D.
Published: October 2013

Wave theoretic modeling was applied to obtain sensitivity kernels representing the amount by which ocean acoustic observables, such as pressure, intensity, or arrival times, are affected by localized sound-speed variations anywhere in the medium. These kernels can be derived using the first Born approximation, yielding an integral representation of observable perturbations as functionals of sound-speed perturbations. The kernel in each integral represents the spatial sensitivity of the observable to sound-speed perturbations in the medium. The travel-time sensitivity kernel represents a full-wave generalization of the highly localized ray kernel from geometric optics. This work extended recent wave-theoretic results for the travel-time sensitivity kernel for short-range propagation in simple environments to long-range transmissions in more complicated ocean environments relevant to ongoing propagation and inversion experiments. It was shown that the geometry of the wave-theoretic sensitivity kernels is related to the geometry of Fresnel volumes surrounding eigenrays, provided that the effects of refraction are taken into account for the calculation of the latter. [Work supported by ONR.]
Spice, internal waves, and sound speed in the upper ocean
Authors: Rudnick Daniel L.
Published: October 2013

Sound-speed variations in the upper ocean may be caused by spice fluctuations or isopycnal tilt associated with internal waves. Given finely resolved fields of temperature and salinity, the relative effects of spice and tilt on sound-speed can be ascertained. For example, in a 1000-km section in the North Pacific thermocline, root-mean-square sound-speed variability in the horizontal caused by spice is roughly one-half that caused by tilt. Sound-speed variability is almost exclusively caused by spice in the nearly unstratified mixed layer. During the June 2004 North Pacific Acoustics Laboratory (NPAL) Spice04 mooring deployment cruise, fine-scale hydrographic observations were made with the newly developed Underway CTD. Observations on a horizontal scale of 10 km and a vertical scale of 5 m show strong spice-caused sound-speed variability in the remnant of the winter-mixed layer. The largest sound-speed changes were greater than 6 m/s in a horizontal distance of tens of kilometers. The effect of these changes on acoustic propagation is a topic of continuing study.
The long-range ocean acoustic propagation experiment (LOAPEX) observable: Modal content as a function of arrival time. Part B. Simulation results
Authors: Wolfson Michael , Henyey Frank
Published: October 2013

Following the approach described in Part A, we present the acoustic mode content for fixed frequency, range, travel time, and time windowsize by performing broadband full-wave simulations using a wide-angle, parabolic equation model. We use a realistic stratification and internal wave spectrum to predict the acoustic arrival structure. The modal content is extracted using the same technique as we intend to use on the LOAPEX vertical line arrays (especially the deep array). Comparing simulations with and without internal waves reveals the additional modal spreading due to scattering.
Some common error mechanisms in making STI intelligibility measurements
Authors: Mapp Peter A.
Published: October 2013

STI and its derivatives (RaSTI and STIPa) have become the internationally accepted methods for acoustically measuring the potential intelligibility performance of both sound systems and rooms. Their use has unquestionably brought about a significant improvement in public address/voice alarm system quality and intelligibility. However, in practice, many of the measurements made on site may be unwittingly based on flawed techniques. The paper examines a number of common problems found to affect measurement accuracy. Significant differences between different measurement platforms and techniques are reported. Furthermore, different stimulus formats and even their recording and playback medium are also shown to potentially affect the final result. It is shown that neither STI nor STIPa, in their current formats, accurately predicts the intelligibility of sound systems with irregular frequency responses, particularly when these are operating in reverberant, high signal-to-noise environments, a common effect found in real-world voice alarm and emergency sound systems.
Acoustical retrofit in residential buildings
Authors: George Ballard W.
Published: October 2013

This paper deals with situations where for some reasons problems arise, and one has to apply noise control measures after or near the end of construction. Three cases are discussed. In two of these, recommendations for window acoustical performance were not implemented. In one case, window improvement was needed to achieve consistency with documentation given to the city and to meet design goals. The owner elected to use the option of improved windows combined with sound absorption in terms of a high-performing carpet. In another case, again window recommendations were not followed, and a curtain wall with Lexan lights also contributed to excessive exterior-to-interior noise levels up to approximately 10 dB. A spaced-out gypsum board inner wall layer arrangement, with ventilation openings, was developed by the architect. The proposed mitigation arrangement involved trade-offs regarding acoustical separation and privacy between units. The third case involved a new hotel, where kitchen-serving equipment, not shown on plans provided, created rumble that resulted in complaints regarding one guest unit. A menu of corrective measures was provided, which could be implemented in sequential fashion.
An investigation of hearing threshold shift in bats due to blast wave pressure
Authors: Pater Larry , Brittan-Powell Elizabeth , Moss Cynthia , Dooling Robert , Loubeau Alexandra , Sparrow Victor
Published: October 2013

A project is described to determine damage to chiropteran (bat) hearing by shock waves such as those emitted by weapons and explosions. Experimental and analytical means will be used to accurately define the stimulus, particularly as regards wave form and spectra in the frequency range 10–100 kHz in which bat hearing is sensitive. Initial results regarding the stimulus as well as hearing thresholds determined via the auditory brainstem response are presented. [Work supported by US Army Engineer Research and Development Center CERL.]
Acoustic adaptation hypothesis in macro- and micro environments: An analysis of frog calls
Authors: Yao Yuan , Lin Ying
Published: October 2013

The acoustic adaptation hypothesis states that acoustic signals are structured so as to maximize their performance under the constraints of the environmental acoustics that characterize their native habitats. However, less attention has been paid to the channels in which acoustic communication takes place and the specific constraints that different channels put on acoustic signals. For frog calls, the channel characteristics depend on two factors: the macro environment—such as the habitat; and the micro environment—such as the sites of the sender and receiver. The data in our analysis came from recordings of 81 species of frogs in French Guyana. These species span a variety of macro environments, such as forest, coastal marsh, and savanna, and a variety of micro environments, such as on vegetation, on ground, and under litter. Two methods—spectrogram correlation and hidden markov models—are used to derive a similarity matrix between these calls. The results indicate that calls show a higher similarity within the same macro environment than between different macro environments. On the other hand, measurements of spectral and temporal features suggest that the micro environment also plays a role, while its effect is more salient for frequency components than for time components.
Relating the performance and perception of phrasal boundaries
Authors: Krivokapic Jelena
Published: October 2013

This study examines the correspondence between the production of prosodic structure and perceptual judgments regarding prosodic boundary strength. In the production component of the study, three speakers read sentences in which one specific juncture is manipulated (varying in syntax, position in sentence, and phrase length) to elicit phrasal boundaries of differing strengths. Lengthening and pause duration at the boundary were measured. The same sentences, in written form, were presented to a second different group of three speakers who provided estimates of the strength of the target boundary on a scale of eight degrees. The results of the production and the estimation portions of the experiment demonstrate significant correlations between the production boundary strength as reflected in durational properties at the juncture and the boundary strength as estimated in the judging task. These correlations are roughly linear. Further, in both the production and perception domains, a range of boundary strength is exhibited rather than a small discrete set of boundary types. We also examine whether speaker’s own boundary strength estimates agree with their productions to a greater extent than estimates of other speakers. [Work supported by NIH.]