bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical modes with sediment absorption in generalized Pekeris waveguides
Authors: Henyey Frank S. , Tang Dajun , Reynolds Stephen A.
Published: October 2013

The eigenvalue spectrum for vertical modes in a system consisting of a water layer overlying sediments modeled as an infinitely deep fluid region with absorption is investigated. These eigenvalues are the square of the horizontal (complex) wavenumbers. The sound speed in the water is assumed smaller than that in the sediments. The dependence of modes on the absorption coefficient as a parameter is of primary concern. The nature of the eigenvalues is related to the amount of absorption in sediments. The main result is that as the amount of absorption is raised, leaky modes (which are not eigenvalues in the absence of absorption) become true discrete modes. This behavior, not present in perturbation theory, is physically explained. [Work supported by ONR.]
Aperture size, materiality of the secondary room and listener location: Impact on the simulated impulse response of a coupled-volume concert hall
Authors: Ermann Michael , Johnson Marty E. , Harrison Byron W.
Published: October 2013

By adding a second room to a concert hall, and designing doors to control the sonic transparency between the two rooms, designers can create a new, coupled acoustic. Concert halls use coupling to achieve a variable, longer and distinct reverberant quality for their musicians and listeners. For this study, a coupled-volume concert hall based on an existing performing arts center is conceived and computer-modeled. It has a fixed geometric volume, form and primary-room sound absorption. Ray-tracing software simulates impulse responses, varying both aperture size and secondary-room sound absorption level, across a grid of receiver (listener) locations. The results are compared with statistical analysis that suggests a highly sensitive relationship between the double-sloped condition and the architecture of the space. This line of study aims to quantitatively and spatially correlate the double-sloped condition with (1) aperture size exposing the chamber, (2) sound absorptance in the coupled volume, and (3) listener location.
Measurement of the acoustic characteristics of the concert hall at the Sydney Opera House
Authors: Bassett John , Cabrera Densil
Published: October 2013

The Sydney Opera House Trust is considering making changes to its Concert Hall. Prior to any alteration, the Acoustics group at the University of Sydney has sought to document the hall. The main measurements were made for 48 receiver locations and 6 source locations, using omnidirectional measurement microphones, B-format (Soundfield) microphones and dummy head microphones in every receiver position. The measurements included impulse responses, anechoic music recordings, and recordings of a calibrated sound power source. Results documented by previous practitioners and researchers are described and comparison is made with the recent results.
A full simulation of the Quetzal echo at the Mayan pyramid of Kukulkan at Chichen Itza in Mexico
Authors: Declercq Nico F. , Degrieck Joris , Briers Rudy , Leroy Oswald
Published: October 2013

It is well known that a handclap in front of the staircase of the pyramid produces an echo that sounds similar to the chirp of the Quetzal bird. This phenomenon occurs due to diffraction. There exist some publications concerning this phenomenon and even some first attempts are reported to simulate it. However, no full simulation (amplitude, frequency, time) has ever been reported before. The present work presents a simulation which is based on the theory of the diffraction of plane waves and which takes into account continuity conditions. The latter theory is the building block for an extended theory that tackles the diffraction of a spherical sound pulse. By means of these principles it is possible to entirely simulate the echo following a handclap in front of the staircase. [Work supported by The Flemish Institute for the Encouragement of the Scientific and Technological Research in Industry (I.W.T.)]
Geoacoustic inversion of range-dependent shallow-water data using a complex plane-wave reflection coefficient approach
Authors: Stotts Steven A. , Knobles David P. , Koch Robert A.
Published: October 2013

The inversion of range-dependent broadband data in shallow water is presented using a previously developed approach with rays and complex bottom plane-wave reflection coefficients [Stotts, J. Acoust. Soc. Am. 109, 2334 (2001)], allowing separation of seabed physics from water column contributions. Using geometrical optics, waterborne eigenray characteristics are calculated once and stored. Model fields are calculated by including reflection coefficient contributions from each bottom interaction and are evaluated for each perturbation of the seabed properties using simulated annealing to minimize a Bartlett-type cost function. Inversion results from range-independent and -dependent data taken during recent experiments off the coast of Florida are presented using a two-layer model. Implosive source broadband data and XBTs were recorded out to 10 km from a bottom-mounted, 52-element array 229-m deep. Grab samples obtained during the experiment show a thin, hard, crusted surface sediment. Inversions reveal an underlying softer sediment. Model time series using one inverted parameter set are compared to the data obtained from sources at different ranges. Data arrivals are compared to eigenray arrivals providing further propagation insight. Consistent inversion results from other forward models are discussed.
Dan Johnson’s impact on hearing research
Authors: Shotland Lawrence I.
Published: October 2013

Daniel L. Johnson is well known for his many technical contributions to noise research. Throughout a long and distinguished career at Wright–Patterson Air Force Base, Dan published the results of several significant experiments, including his landmark experiments on asymptotic threshold shift and exposure to impulse noise. His work in the area of noise exposure laid much of the groundwork for a greater understanding of the physiologic response to hazardous noise, much of which has since been incorporated in national and international standards. Dan is highly regarded for his tireless work on technical and advisory committees in noise, and most recently, ototoxicity. Throughout his career, Dan has adhered to a self-imposed standard of intellectual honesty and discovery. Dan’s most recent endeavor, the development of a personal noise dosimeter designed for self-monitoring by the employee, is characteristic of his creativity and energy. Perhaps less well known are his contributions over the years to the success of his younger colleagues. He has accomplished this in an unselfish and egalitarian manner, oftentimes challenging and even contradicting his own research. The focus of this talk will elaborate on these facets of Dan’s professional contributions.
The mid-duration hump in the intensity-difference limen as a function of frequency: Further evidence for the frequency–time listening window of the human ear
Authors: Nizami Lance , Jesteadt Walt
Published: October 2013

It has been suggested that the ear has a frequency–time listening window and that the stimulus that occupies the fewest frequency–time windows, i.e., that which has the smallest product of effective bandwidth and effective duration, should result in the largest intensity-difference limen (DL) [Van Schijndel et al., J. Acoust. Soc. Am. 105 (1999)]. Van Schijndel et al. identified the Gaussian-shaped tone-pip as the optimal stimulus, obtaining DLs at 1 kHz and 4 kHz. The DLs were greatest for the tone-pips whose frequency–time window was one critical band wide and 4 cycles long in equivalent square duration D (envelope duration/ 3.19). Here, DLs for Gaussian-shaped 250-Hz tone-pips were obtained from 5 subjects for Ds of 1.25–22.57 ms at levels of 40, 50, 60, 70, 80, and 90 dB SPL. These data were combined with earlier results showing a mid-duration rise at 40–60 dB SPL for Gaussian-shaped tone-pips of 6.5 kHz, 2 kHz, and 500 Hz. The peak in the DL is sharp for 6.5 kHz but flattens as frequency drops, being replaced by a broad rise for 250 Hz. The highest DLs correspond to approximately 4 cycles in D, not far from the ringing duration calculated as the inverse of the critical bandwidth.
A measure of aperiodicity content in a speech signal
Authors: Deshmukh Om D. , Espy-Wilson Carol Y.
Published: October 2013

Most of the current aperiodicity detectors measure aperiodicity indirectly, in which the absence of periodic component in a nonsilent region is termed as aperiodicity. Such indirect measurements are inadequate and can be misleading especially in cases like voiced fricatives or breathy vowels. This motivated us to develop a direct measure of aperiodicity which is independent of the periodicity measure. The speech signal is passed through a 60-channel gamma tone auditory filterbank. Average Magnitude Difference Function (AMDF) is computed on the envelope of each channel. The randomness in the distribution of the AMDF dips is the basis for the measure of the aperiodicity whereas the measure of the periodicity is based on the occurrence of the dips at multiple locations. The system was evaluated on the MOCHA database, which has simultaneous recording of the EGG data, and on the TIMIT database. Preliminary analysis shows that the aperiodicity and voicing accuracy on a per frame basis are 95% and 90.3%, respectively. In voiced fricatives and voiced stops, high aperiodicity and high periodicity were detected in 21.6% of the frames. Note that not all these sounds necessarily had both the sources prominent.
Microphone and production techniques for stereophonic sound reinforcement
Authors: Brown Jim
Published: October 2013

Producing a stereo image for many listeners in a large room is a far more demanding task than doing so for a few listeners in a living room, and very different acoustic systems of both microphones and loudspeakers are required for large room listening as compared to small room listening. As long ago as the 1930s, William B. Snow and his team at Bell Labs clearly understood these diffferences. Their thoughts on the subject are very different from those of Blumlein, and are well documented. Nearly all thinking and writing about microphone technique since Snow has focused on recording and playback for a single listener centered between two or three loudspeakers in a small room. Stereophonic reinforcement imposes a very different set of requirements, in that both listeners and performers are distributed over a wide area, and the system is a closed loop (that is, the potential for acoustic feedback must be considered).
History of bioresponse to vibration in the Acoustical Society of America
Authors: Weisenberger Janet M.
Published: October 2013

Human response to vibratory stimulation of the skin surface has long been considered an aspect of the sense of touch; however, the debate over whether vibration was one aspect of pressure sensation, as espoused by von Frey in the late 1800s, or a separate sense, as argued by Katz (1925), focused attention on this mode of stimulation. Experimental investigations from the 1920s to the 1960s by Knudsen, Geldard, Sherrick, Verrillo, Mountcastle, and others provided basic data on vibrotactile perception and the neural transduction of vibratory stimulation. Within the Acoustical Society of America, work on bioresponse to vibration has included not only basic investigations of vibrotactile perception and physiology, but also studies of the loss of sensitivity resulting from intense hand-arm vibration induced by occupational use of chainsaws and jackhammers, studies of human response to whole-body vibration, and evaluations of the utility of vibrotactile devices for communication of speech to hearing-impaired persons. Contributions in each of these areas, as well as future research directions, are discussed.
Update and clarifications on analytic studies for nuclear emissions during acoustic cavitation
Authors: Nigmatulin Robert I. , Lahey R. T. , Taleyarkhan R. P. , West C. D.
Published: October 2013

A one-dimensional hydrodynamic shock (HYDRO) code was developed to numerically evaluate the conservation equations of each phase during bubble growth and collapse. This code includes the Mie–Gruniesen equations of state and Born–Mayer potential functions, which are known to be valid for highly compressed fluids. In particular, for acetone these equations of state are based on the shock wave adiabat data, and they implicitly specify the effect of the induced radiation field and the dissociation and ionization processes that take place during plasma formation within imploding bubbles. Moreover, relevant energy losses and the effect of both molecular and electron conductivity were taken into account, and the resultant HYDRO code allowed for the evaluation of shock wave interaction using the well-established Godunov numerical technique. Bubble dynamics were studied in deuterated acetone for conditions typical of those in our experiments. It was found that highly compressed conditions suitable for thermonuclear fusion were predicted, and the results were sensitive to the values of the phase change (that is, accommodation) coefficient, a, and the liquid pool temperature To.
Development of infants’ pitch perception
Authors: Clarkson Marsha G.
Published: October 2013

Several studies demonstrate that by 7 months of age infants can hear the pitch of the missing fundamental for tonal complexes and that the same acoustic cues used by adults permit infants to perceive pitch. Infants and adults were tested in an operant conditioning procedure and learned to categorize tonal complexes with differing spectra according to the pitch of the missing fundamental. Responses to spectral manipulations that reduce the salience of pitch suggested that the strength of the pitch percept may be weaker and the use of temporal cues may be poorer for infants than for adults. Other work utilizing an iterated rippled noise stimulus (IRN) attempted to quantify these developmental differences. Applying progressively greater attenuation to the delayed noise in an IRN progressively decreases the strength of the pitch percept evoked by the stimulus. The maximum attenuation for which listeners detect changes in pitch estimates the strength of their pitch percept. Such thresholds revealed that the strength of the pitch percept evoked by IRN was significantly weaker for infants (6.7 dB) than for adults (19.1 dB). In combination, these findings suggest that temporal mechanisms for processing pitch may be particularly immature in infants.
Speech intelligibility in complex acoustic environments in young children
Authors: Litovsky Ruth
Published: October 2013

While the auditory system undergoes tremendous maturation during the first few years of life, it has become clear that in complex scenarios when multiple sounds occur and when echoes are present, children’s performance is significantly worse than their adult counterparts. The ability of children (3–7 years of age) to understand speech in a simulated multi-talker environment and to benefit from spatial separation of the target and competing sounds was investigated. In these studies, competing sources vary in number, location, and content (speech, modulated or unmodulated speech-shaped noise and time-reversed speech). The acoustic spaces were also varied in size and amount of reverberation. Finally, children with chronic otitis media who received binaural training were tested pre- and post-training on a subset of conditions. Results indicated the following. (1) Children experienced significantly more masking than adults, even in the simplest conditions tested. (2) When the target and competing sounds were spatially separated speech intelligibility improved, but the amount varied with age, type of competing sound, and number of competitors. (3) In a large reverberant classroom there was no benefit of spatial separation. (4) Binaural training improved speech intelligibility performance in children with otitis media. Future work includes similar studies in children with unilateral and bilateral cochlear implants. [Work supported by NIDCD, DRF, and NOHR.]
Learning problems, delayed perceptual development, and puberty
Authors: Wright Beverly A. , Zecker Steven G. , Reid Miriam D.
Published: October 2013

Language-based learning problems affect approximately one person in twelve with no other obvious signs of disorder. Many of these individuals have accompanying deficits in nonlinguistic perception. To determine whether age influences the magnitude of these deficits, thresholds on a set of auditory masking tasks were measured in individuals with learning problems and controls ranging in age from 6 years to adult. Performance improved with increasing age in both groups. However, the thresholds of the individuals with learning problems were most similar to those of controls approximately 2–4 years younger on every task, suggesting that the perceptual development of the affected individuals was delayed by a constant amount. Further, on the subset of conditions on which controls reached adult levels of performance after 10 years of age, the improvement of affected individuals halted at 10 years of age, suggesting that puberty may play a critical role in human perceptual development. Taken together, these data support the idea that some learning problems result from a neuromaturational delay, of unknown breadth, and indicate that neurological changes associated with puberty prevent the complete resolution of delayed perceptual development. [Work supported by NIH/NIDCD.]
Applications of psychophysical models to the study of auditory development
Authors: Werner Lynne
Published: October 2013

Psychophysical models of listening, such as the energy detector model, have provided a framework from which to characterize the function of the mature auditory system and to explore how mature listeners make use of auditory information in sound identification. The application of such models to the study of auditory development has similarly provided insight into the characteristics of infant hearing and listening. Infants intensity, frequency, temporal and spatial resolution have been described at least grossly and some contributions of immature listening strategies to infant hearing have been identified. Infants psychoacoustic performance is typically poorer than adults under identical stimulus conditions. However, the infant’s performance typically varies with stimulus condition in a way that is qualitatively similar to the adult’s performance. In some cases, though, infants perform in a qualitatively different way from adults in psychoacoustic experiments. Further, recent psychoacoustic studies of children suggest that the classic models of listening may be inadequate to describe the children’s performance. The characteristics of a model that might be appropriate for the immature listener will be outlined and the implications for models of mature listening will be discussed. [Work supported by NIH grants DC00396 and by DC04661.]
Imaging with the DORT method
Authors: Prada Claire , Kerbrat Estelle , Thomas Jean-Louis , Fink Mathias
Published: October 2013

The decomposition of the time reversal operator (DORT) method applies to active detection and focusing of acoustic waves using arrays of transmitters and receivers. This method allows detection and selective focusing on scatterers through complex media. It consists in the construction of the invariants of the time reversal process, that are also the singular vectors of the array response matrix. The DORT method is particularly interesting for detection in inhomogeneous media when the acoustic properties are poorly known. However, if an estimate of the medium’s Green function is available, images of the medium can be formed by backpropagation of the dominant eigenvectors. For the detection of defect in scattering media like titanium, the method is useful to separate the echo of a defect from the microstructure contribution and thus to reduce speckle noise. We will also see that the time reversal operator can be interpreted as a pseudocovariance matrix like those encountered in classical array signal processing. And as shown by Anthony J. Devaney [J. Acoust. Soc. Am. 110, 2617 (2001)], nonlinear estimators like MUSIC can be applied to achieve high resolution. These different points will be illustrated through several experimental results.
Horizontal-array beamforming using the waveguide invariant
Authors: Rouseff Daniel , Turgut Altan
Published: October 2013

It has been shown that with a horizontal array and incoherent processing, the measured acoustic intensity produced by a distant source exhibits striations when plotted versus range and frequency. The striations are a consequence of interference between pairs of propagating acoustic modes, and the waveguide invariant describes their slope. The present work extends this concept to coherent processing, such as beamforming with a horizontal array. Equations are derived that describe the trajectories of the striations observed in LOFARgrams. (LOFARgrams display the time-evolving spectrum of a beamformer for a particular look direction.) The validity of the equations is first tested in numerical simulations and then tested using horizontal-array data from the ONR Asian Seas International Acoustics Experiment (ASIAEx) conducted in the South China Sea. The effect of mismatch between the beamformer look direction and the true bearing of the source is also discussed. [Work supported by ONR.]
The loudspeaker as musical instrument: An examination of the issues surrounding loudspeaker performance of music in typical rooms
Authors: Moulton David
Published: October 2013

The loudspeaker is the most important and one of the most variable elements in the electroacoustic music performance process. Nonetheless, its performance is subject to a ‘‘willing suspension of disbelief’’ by listeners and its behavior and variability are usually not accounted for in assessments of the quality of music reproduction or music instrument synthesis, especially as they occur in small rooms. This paper will examine the aesthetic assumptions underlying loudspeaker usage, the general timbral qualities and sonic characteristics of loudspeakers and some of the issues and problems inherent in loudspeakers interactions with small rooms and listeners.
Geoacoustic characterization of a range-dependent environment using towed array data
Authors: Fallat Mark , Nielsen Peter , Siderius Martin
Published: October 2013

This paper describes geoacoustic characterization of a range-dependent environment using towed horizontal array data. Data from multiple points along a track are inverted using a short-range, range-independent scheme and the results are combined to produce a range-dependent model. Data from the MAPEX 2000 experiment, conducted by SACLANT Centre in the Mediterranean Sea, are used to determine seabed properties for a range-dependent environment. Inversion results are compared for both normal-mode and ray theory forward models. The layering structure of the range-dependent model compares favorably with a high-resolution seismic profile.
Hearing loss and the central auditory system: Implications for hearing aids
Authors: Frisina Robert D.
Published: October 2013

Hearing loss can result from disorders or damage to the ear (peripheral auditory system) or the brain (central auditory system). Here, the basic structure and function of the central auditory system will be highlighted as relevant to cases of permanent hearing loss where assistive devices (hearing aids) are called for. The parts of the brain used for hearing are altered in two basic ways in instances of hearing loss: (1) Damage to the ear can reduce the number and nature of input channels that the brainstem receives from the ear, causing plasticity of the central auditory system. This plasticity may partially compensate for the peripheral loss, or add new abnormalities such as distorted speech processing or tinnitus. (2) In some situations, damage to the brain can occur independently of the ear, as may occur in cases of head trauma, tumors or aging. Implications of deficits to the central auditory system for speech perception in noise, hearing aid use and future innovative circuit designs will be provided to set the stage for subsequent presentations in this special educational session. [Work supported by NIA-NIH Grant P01 AG09524 and the International Center for Hearing & Speech Research, Rochester, NY.]
Hearing aids: Do they help and, if so, how does one know?
Authors: Humes Larry E.
Published: October 2013

For those individuals with sensorineural hearing loss, ranging from mild to severe in degree, the conventional hearing aid is the most appropriate rehabilitative device available. Despite the fact that such devices have been available commercially for over 60 years, until recently, relatively little research has been directed at evaluating the effectiveness of these rehabilitative devices. How does one evaluate the effectiveness of a hearing aid as a rehabilitative device? Should effectiveness be based on the relative improvement in communication with and without the hearing aid, typically referred to as hearing-aid benefit, the satisfaction of the consumer with the device, or simply whether and how much the hearing aid is used? How are these aspects of hearing-aid effectiveness or outcome measured? Are the measures of hearing-aid outcome related to one another? What evidence is there regarding the effectiveness of contemporary hearing aids? Recent research regarding these and other related questions will be reviewed in this presentation. [Work supported, in part, by NIA.]
Basic physics boundary conditions of acoustically driven, inertial confinement fusion
Authors: Forsley Lawrence , August Robert , Whitlock Robert , Deletrez Jacques
Published: October 2013

This paper defines boundary conditions derived from the basic physics of fusion and applies them to both laser driven and acoustically driven Inertial Confinement Fusion (ICF). Several experimental and theoretical papers, in addition to some patents, hold open the promise of acoustically driven ICF. There are several factors common to both drivers that must be taken into account. In particular, it has been observed in laser driven ICF plasmas that criteria on the ion temperature, the confinement time, the core density, and the minimum core radius must be satisfied to achieve fusion. The relationship of these criteria to acoustically driven inertial confinement will be discussed.
Viability of spectral enhancement with harmonic stimuli
Authors: DiGiovanni Jeffrey J.
Published: October 2013

Loss of spectral resolution is an established consequence of sensorineural hearing loss. Traditional hearing aid design includes amplification and compression. These do not, however, account for the loss in frequency resolution. Recently, spectral enhancement processing has been designed to at least partially restore aspects of frequency resolution. The critical feature of this design is to increase the peak to trough ratio of the speech spectrum. These have been implemented with mixed success [e.g., Miller et al. (1999); Franck et al. (1999)]. More recently, DiGiovanni et al. (2002) showed promising results for normal and hearing-impaired subjects with psychophysical noise stimuli. The goal of this study was to expand these results to harmonic stimuli while adding peaks at fixed formant places within the spectrum. In that regard, subjects listened in two psychophysical experiments: detecting an F2-like spectral increment in a broadband harmonic complex and detecting the increment with an additional fixed formant peak added at an appropriate F1 place. Preliminary results show that normally hearing subjects have an improved ability to detect a narrowband tone complex when there is a spectral decrement at frequencies adjacent to the increment. These results are further support that the idea of spectral enhancement is viable.
Neuroimaging of speech recognition under conditions of spectral reduction and frequency upshift
Authors: Chiu C.-Y. Peter
Published: October 2013

In the current study explored the cortical dynamics of speech recognition, given spectral reduction and frequency upshifts, using functional MRI. Subjects with normal hearing either rested or listened to speech under different conditions. In the 8-channel condition, natural speech was processed by an 8-channel sinewave vocoder to remove its fine spectral details [Shannon et al., J. Acoust. Soc. Am. 104, 2467 (1998)]. In the upshifted condition, the carrier center frequency of each of the 8 channels was further shifted upward in frequency from the corresponding analysis band by ‘‘6 mm’’ in cochlear frequency space [Fu and Shannon, J. Acoust. Soc. Am. 105, 1889 (1999)]. All subjects received a brief practice session with the speech stimuli prior to scanning. In Experiment 1, subjects listened to nonmonosyllabic words and pressed a key whenever they heard a concrete noun. In Experiment 2, subjects listened to high context sentences (SPIN) and pressed a key whenever they recognized all the words in a particular sentence. Preliminary data suggested that, compared to rest, all speech conditions evoked comparable activities in largely similar sets of bilateral superior temporal regions, with relatively minor differences between words and sentences. Activation appeared to be least diffuse in the natural speech condition.
Further tests of the ‘‘two pitch mechanisms’’ hypothesis
Authors: Micheyl Christophe , Oxenham Andrew
Published: October 2013

To further investigate the hypothesis that F0 is encoded via different mechanisms for resolved and unresolved harmonics, we measured F0 difference limens (DLF0’s) between two groups of harmonics that were both resolved, both unresolved, or differed by resolvability (one resolved, one unresolved). In a first experiment, the complexes were filtered in the same or a different frequency region and presented sequentially; listeners had to indicate which had the higher pitch. In the second experiment, two pairs of simultaneous complexes filtered in a different region were presented sequentially; subjects had to indicate the interval containing the pair of complexes with different F0’s. To reduce possible pitch-pulse-asynchrony cues, the starting phase of the entire complex was randomized across spectral regions in. The results of the first experiment showed that for tracks where the higher F0 was in the higher spectral region (consistent pitch-timbre cues), DLF0’s were consistently smaller for same-resolvability than for different-resolvability complexes. On the other hand, the preliminary results of the second experiment, using simultaneous complexes, do not provide clear support for the hypothesis that DLF0’s for resolved versus unresolved comparisons are impeded by ‘‘translation’’ noise between the output of the two pitch mechanisms. [Work supported by NIDCD R01DC05216.]
The effects of three temporal cues on the detection of increments and decrements in intensity
Authors: Yoon Yang-soo , Gooler David M.
Published: October 2013

This study investigated the effect of three temporal cues: interonset interval, interpulse interval, and pulse duration, on auditory intensity detection. Eight adults with normal hearing served as subjects. The level detection (target increment or decrement) ability of listeners was measured in a sequential oddball paradigm where targets occurred randomly. The experiment used spectrally identical, broadband noise bursts as standard (30 dB above threshold to a train of standard pulses) and target pulses (1, 2, and 3 dB re: standard pulse level). At each target level performance was measured for different pulse interonset intervals (20 ms to 180 ms), interpulse intervals (10 ms to 90 ms), and pulse duration (10 ms to 90 ms, 0.5 ms rise/fall time). Overall, the results showed that the performance of the intensity detection was more influenced by the interpulse interval than the interonset interval. Also, performance was dependent on pulse duration since a poorer performance with longer interpulse intervals could be improved by increasing pulse duration. Performance at different inter-pulse intervals may reflect different perceptual strategies for comparing acoustic events that occur in a sequence.
Effect of duration and inter-stimulus interval on auditory temporal order discrimination in young normal-hearing and elderly hearing-impaired listeners
Authors: Narendran Mini M. , Humes Larry E.
Published: October 2013

Increasing the rate of presentation can have a deleterious effect on auditory processing, especially among the elderly. Rate can be manipulated by changing the duration of individual components of a sequence of sounds, by changing the inter-stimulus interval (ISI) between components, or both. Consequently, when age-related deficits in performance appear to be attributable to rate of stimulus presentation, it is often the case that alternative explanations in terms of the effects of stimulus duration or ISI are also possible. In this study, the independent effects of duration and ISI on the discrimination of temporal order for four-tone sequences were investigated in a group of young normal-hearing and elderly hearing-impaired listeners. It was found that discrimination performance was driven by the rate of presentation, rather than stimulus duration or ISI alone, for both groups of listeners. The performance of the two groups of listeners differed significantly for the fastest presentation rates, but was similar for the slower rates. Slowing the rate of presentation seemed to improve performance, regardless of whether this was done by increasing stimulus duration or increasing ISI, and this was observed for both groups of listeners. [Work supported, in part, by NIA.]
A proposed definition for the induced noise control parameter
Authors: Maidanik G. , Becker K. J.
Published: October 2013

The response of an externally force-driven master dynamic system is examined under two conditions. In the first, the master dynamic system is in isolation and the (quadratic) response is stated in terms of its stored energy E00(ω), where (ω) is the (angular) frequency. In the second, the master dynamic system is passively coupled to an adjunct dynamic system that is not externally driven. The response of the master dynamic system, that is subjected to the same external force drive, is changed due to the couplings. The change is from E00(ω), in isolation, to E0(ω), when coupled. The induced noise control parameter ξ(ω) is then defined: ξ(ω)=[E0(ω)/E00(ω)]. The smaller ξ(ω) is, the more benefit, by the couplings, is accrued to the noise control of the master dynamic system. When ξ(ω) exceeds unity, by definition, an induced noise control reversal occurs. Illustrations of an induced noise control are provided in terms of a master dynamic system represented by an (harmonic) oscillator and an adjunct dynamic system represented by a set of satellite (harmonic) oscillators. The satellite oscillators are not coupled to each other; they are individually coupled to the master oscillator only. A coupling may include a combination of mass, stiffness, and gyroscopic elements.
Issues in the use of acoustic cues for auditory scene analysis
Authors: Bregman Albert S.
Published: October 2013

Issues concerning auditory scene analysis (ASA) raised by the previous speakers will be discussed: (1) Disorders of ASA in humans can tell us about the weighting of cues in ASA. (2) The apparent weakness of spatial cues for ASA may simply show that they interact strongly with other ASA cues (c.f., recent research in the author’s lab). (3) The power of harmonic relations among partials as a grouping cue is not guaranteed, but depends on many other factors. (4) Abstract models of ASA may require the peripheral auditory system to carry out analyses that are questionable, based on current psychophysical and physiological findings. Is this where psychologists and computational ASA (CASA) modelers part company? (5) The ‘‘old-plus-new heuristic,’’ one of the most potent ASA mechanisms, is neglected by existing CASA models. (6) The different roles of bottom-up and top-down processes (e.g., in ‘‘exclusive allocation’’ of sensory evidence) should be reflected in models. (7) Should the output of a CASA system be the reconstructed signal of a single source, as a front end to a recognition system, or should grouping mechanisms merely form an interacting part of a larger system that outputs a higher-level description (e.g., a series of words)?
Richard H. Bolt introduced me to acoustics, and I am still engaged
Authors: Dyer Ira
Published: October 2013

I arrived at the MIT Acoustics Laboratory in 1948, and quickly learned from Dick Bolt that U.S. submarines needed coatings to reduce vulnerability via active sonar detection. All who remember Dick will be familiar with his next step: He brought me to Robert Blizzard and A. Wilson Nolle, both then at the Lab, from whom I learned in detail how to measure and then how to understand the dynamic moduli of rubber-like materials. My path, of course, widened to include medical acoustics (under the leadership of Theodore Hueter) and scattering (Phillip Morse and Uno Ingard). Fast-forward to the present. Rubber-like materials are not only in use as submarine coatings to avoid detection by active sonars, but also to reduce noise radiated by submarines. Further, such materials cover submarine acoustic arrays to reduce flow–noise interference with signals received by such arrays. The problem that most engages me today is the stochastic nature of sound propagation in the ocean, a problem that has the practical consequence of degraded sonar performance. In the spirit of Dick, I will present snippets of my current work, with the hope of painting the big picture that he always did so well.
Experimental measurements of lung resonant frequencies in a bottlenose dolphin (Tursiops truncatus) and white whale (Delphinapterus leucas)
Authors: Finneran James J.
Published: October 2013

An acoustic backscatter technique was used to estimate in vivo whole-lung resonant frequencies in a bottlenose dolphin (Tursiops truncatus) and a white whale (Delphinapterus leucas). Subjects were trained to submerge and position themselves near an underwater sound projector and a receiving hydrophone. Acoustic pressure measurements were made near the subjects’ lungs while insonified with pure tones at frequencies from 16 to 100 Hz. Whole-lung resonant frequencies were estimated by comparing pressures measured near the subjects’ lungs to those measured from the same location without the subject present. Experimentally measured resonant frequencies and damping ratios were much higher than those predicted using equivalent volume spherical air bubble models. The experimental technique, data analysis method, and discrepancy between the observed and predicted values will be discussed. The potential effects of depth on the resonance frequencies will also be discussed.
Measurements and bioeffects of resonant gas bodies in vivo
Authors: Dalecki Diane
Published: October 2013

The response of resonant gas bodies in vivo (such as the gas filled lung and intestine of mammals) to exposure to low frequency underwater sound was characterized through a series of investigations. Measurements were performed in the laboratory using a specially designed acoustic exposure system, capable of generating maximum acoustic fields of ∼200 dB re 1 μPa for frequencies spanning 100–2500 Hz. Both acoustic scattering and pulse-echo ultrasound techniques were used to characterize the response of gas bodies to underwater sound exposure and to determine the resonance frequencies of gas bodies in mammalian tissues in vivo. A series of investigations has demonstrated that the effects of low frequency (∼ 100–2500 Hz) underwater sound can be significant in and near tissues that contain resonant gas bodies. For example, mice exposed to underwater sound at the resonance frequency of their lung exhibited lung damage and the extent of tissue damage increased with increasing pressure amplitude. Similar types of investigations were performed with mammalian lungs of various sizes and with intestinal gas in vivo.
Target strength and density structure of Hawaiian mesopelagic boundary community patches
Authors: Benoit-Bird Kelly , Au Whitlow
Published: October 2013

A broadband sonar system and digital camera with strobe lights were mounted on a vertically profiling frame with a depth sensor. The target strengths and densities of animals within individual mesopelagic boundary community patches were investigated as a function of depth. Simultaneous echosounder surveys permitted comparison of density estimates from echo-energy integration and echo-highlight counting. Target strength values suggest nearshore boundary community animals are primarily myctophid fishes which was confirmed by preliminary photographic evidence. Target strength varied significantly as a function of distance from the shoreline and time. Echo-energy integration estimates of density made with these revised target strengths compare well with those made with echo highlight counting. These density measures show that previous density estimates were too low but do not change the conclusions of these studies. Vertical microstructure in density was apparent but animal size and compositional structure was not evident within a patch. Patch edges were abrupt, with no differences in the density or target strength from patch interiors. These edges were generally straight, with a sharp drop in density to the background density of zero. Estimates of animal size as a function of time provide information about the diel migration patterns of these mesopelagic animals.
Supersonic imaging of elasticity
Authors: Fink Mathias , Tanter Michael , Bercoff Jeremy
Published: October 2013

This paper shows the new possibilities of supersonic imaging of elasticity. It combines ultra-high speed ultrasonic imaging of tissues with low frequency supersonic shear sources induced in the body by radiation pressure. We have built an Ultrafast Scanner providing up to 5000 frames/s and using conventional arrays linked to a new beamformer. We will show how this scanner is able to follow in real time tissue displacements induced by the transient propagation of LF shear wave in the human body. From the spatio-temporal evolution of the displacements, a shear elasticity map is constructed using a local inversion algorithm. In order to obtain unbiased shear elasticity map, different configurations of shear sources induced by radiation pressure of focused transducer arrays are used. A very interesting configuration that induces quasi plane shear waves will be described. It used a shear source that moves at supersonic velocities, and that is created by using a very peculiar beam forming in the transmit mode. In vitro and in vivo results will be presented that demonstrate the interest of this new transient elastographic technique.
Bone and tissue conduction of high intensity acoustic energy to the human cochlea
Authors: McKinley Richard , Dancer Armand , von Gierke Henning
Published: October 2013

Noise fields near operating high performance fighter aircraft range from 140 to 150 dB overall sound pressure level. Much of the acoustic energy which is transmitted to the cochlea in a well protected ear (earplugs and earmuffs) arrives by tissue and bone conduction pathways. A better understanding of this transmission of acoustic energy by these biological materials could lead to improved protection and/or methods of actively attenuating this acoustic energy in the cochlea. Associated issues to be discussed are the possible damaging levels of bone/tissue conducted acoustic energy and the actual bone/tissue attenuation. This paper will describe a series of experiments in a recent investigation of bone and tissue conduction of acoustic energy over a broad band of frequencies and a look at the initial results of the first of the studies. [Work supported in part by the Air Force Office of Scientific Research.]
Acoustical analysis and modeling of reciprocating compressors, noise produced by gas pulsation, using four-pole method. I
Authors: Herfat Ali T. , Seel Robert V.
Published: October 2013

Presented in Paper I are the fluid-structure interactions, structural dynamics, and thermodynamic analyses of reciprocating compressors (such as air conditioning and refrigeration reciprocating compressors). The compressor performance can be analyzed using the follows criteria: (1) thermodynamic model of the cylinder process, using the polytropic process model for thermodynamic model of cylinder; (2) suction and discharge valves dynamics analysis and modeling; (3) the valves modeling and the cylinder volume calculation; (4) Effective flow area and effective force area models.
Chicago Transit Authority train passenger environmental noise study
Authors: McDuffee Matt R. , Karner Chris
Published: October 2013

The Chicago Transit Authority (CTA) train system is referred to as the ‘‘L’’ because most of the track throughout the city is elevated. Passengers riding aboard the ‘‘L’’ are often subjected to high levels of noise due to the aging metal girder system that the tracks are perched on, as well as some train cars that are in disrepair. The environmental acoustics class of nine students at Columbia College Chicago decided to quantify exactly how much noise an ‘‘L’’ passenger is subjected to. Using a Quest 2900 integrating sound level meter the class split up and took Leq measurements on all of the seven train lines. Each line was tested in both directions of travel twice, with the meter taking samples every 3 s, which added up to a total of approximately 65 000 samples. The data were then averaged and synthesized into a graph using ESRI ArcView software. The graph is actually a map of the CTA ‘‘L’’ system that is color coded according to the Leq level that the passengers are subjected to between each station. It was interesting to see the difference in noise levels according to the type of track construction.
Effect of atmospheric pressure fluctuations on low frequency and infrasound detection
Authors: Talmadge Carrick L. , Shields Doug
Published: October 2013

A fundamental difficulty in low-frequency and infrasound detection is the so-called ‘‘wind noise’’ problem. At higher (>50 Hz), this wind noise is usually associated with the obstruction formed by the pressure pobe body. In this case, most of this wind noise can be adequately removed by the use of an appropriate wind screen. At lower frequencies (<50 Hz), the magnitude of the intrinsic atmospheric fluctuations appears to be much larger than the flucutations induced by the sensor body. A new large-element (>30 elements) 3-axis pressure sensor array is used to quantify the relative magnitude of the intrinsic and induced pressure fluctuations. Signal processing algorithms are discussed which enchance the signal-to-noise ratio over that obtained using standard beam forming algorithms, by utilizing the localized nature of many of the fluctuations across the array. The effect of the height of the sensor above ground on the magnitude of the observed pressure flucutations is also examined using a 3-axis linear pressure sensor array. Finally, the performance of a single-element porous hose array is compared to that of a large-element array.
Wind noise and the spectrum of atmospheric turbulence pressure fluctuations
Authors: Wilson D. Keith
Published: October 2013

Previous research [S. Morgan and R. Raspet, J. Acoust. Soc. Am. 92, 1180–1183 (1992)] has shown that wind noise is predominantly caused by pressure fluctuations intrinsic to the turbulent atmospheric flow. Therefore it should be possible to predict wind noise from models for turbulent pressure spectra in the atmosphere. Based on simple dimensional analysis and an application of Taylor’s hypothesis, the inertial-subrange power spectrum for turbulent pressure fluctuations should be proportional to f−7/3, where f is frequency. But more recent atmospheric observations and theoretical arguments [J. D. Albertson, G. G. Katul, M. B. Parlange, and W. E. Eichinger, Phys. Fluids 10, 1725–1732 (1998)] suggest that the power spectrum actually goes as f−3/2. In this paper, it is shown that the f−3/2 dependence predicts a much slower decay in wind noise with increasing acoustic frequency than is typically observed. Possible reasons for this discrepancy are discussed.