bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculated wind noise for semi-porous fabric domes
Authors: Abbott JohnPaul R. , Raspet Richard , Noble John , Alberts W. C. Kirkpatrick , Collier Sandra
Published: May 2016

A simple calculation of the wind noise measured at the center of three 2 m diameter semi-porous fabric domes is developed. The calculation provides a model of the measured wind noise and is based on the model for a large porous wind fence enclosure. The model combines the wind noise contributions from (a) the turbulence-turbulence and turbulence-shear interactions inside the domes, (b) the turbulence interactions on the surface of the domes, and (c) the turbulence-shear interactions outside of the domes. Each wind noise contribution is calculated from the appropriate measured turbulence spectra, velocity profiles, correlation lengths, and the mean velocity at the center, surface, and outside of the enclosure. The model is verified by comparisons of the measured wind noise to the calculated estimates of the differing noise contributions and their sum. The calculated estimates indicate that the principle source of low frequency wind noise at the center of the domes is due to the turbulence interactions on the surface of the domes while the turbulence interactions inside the domes and outside of the domes are minimal, and in some cases negligible.
Spectrotemporal modulation sensitivity as a predictor of speech intelligibility in noise for hearing-impaired listeners
Authors: Bernstein Joshua G.
Published: May 2016

The audiogram accounts for only a portion of the variance in speech-reception performance in noise for hearing-impaired listeners. The remaining variance is often attributed to a combination of suprathreshold auditory distortion and non-auditory factors such as cognitive processing. This talk describes a series of studies demonstrating that a suprathreshold measure of sensitivity to spectro-temporal modulation (STM) can account for individual differences in speech-reception scores that are not predicted by the audiogram. STM stimuli are spectrally rippled noises with spectral-peak frequencies that shift over time, akin to modulations in a speech signal. The results show that STM sensitivity correlates to speech-reception performance in noise; that the correlation is ascribed mainly to the low-frequency portion of the stimulus (<2 kHz); and that STM sensitivity can account for individual differences in speech-reception thresholds for hearing-impaired listeners properly fit with individualized frequency-dependent gain. Hearing loss has the largest impact on STM sensitivity for low temporal rates and low carrier frequencies, suggesting a reduced ability to use temporal fine-structure information to detect slow-moving spectral peaks. STM detection is a fast, simple test of suprathreshold auditory function that complements the high-frequency audiogram to account for a substantial proportion of individual variability in speech reception in noise.
Evidence that hidden hearing loss does not vary systematically as a function of noise exposure in young adults with normal audiometric hearing
Authors: Prendergast Garreth , Guest Hannah , Léger Agnès , Munro Kevin , Kluk Karolina , Plack Christopher
Published: May 2016

Cochlear synaptopathy, or “hidden hearing loss,” refers to a loss of synapses between inner hair cells and auditory nerve fibers, and is observed in rodent models as a consequence of noise exposure and/or aging. In humans, cochlear synaptopathy is not thought to be detectable by pure tone audiometry, as thresholds to soft sounds in the rodent models are not permanently elevated. One hundred and forty audiometrically normal participants below the age of 35 and with a range of lifetime noise exposures performed an extensive battery of tests, including electrophysiological measures, psychophysical tests, and speech-in-noise tests. Inter-aural phase discrimination, amplitude modulation detection, and spatial release from masking on a speech task were found to be sensitive to noise exposure; however, these trends are weak and only the phase discrimination task followed the predicted direction (i.e., high noise exposed individuals showing elevated thresholds). None of the electrophysiological measures, including wave I of the ABR, showed a strong relation with noise exposure. The results suggest that either: (i) hidden hearing loss is not prevalent in young normally hearing adults, or (ii) even listeners with comparatively low levels of noise exposure have the disorder and that there is no additional consequence of high levels of exposure.
Gender-based variation in the phonetic representation of boundary tones in Persian declarative and interrogative utterances
Authors: Eshghi Marziye , Eslami Moharram
Published: May 2016

This study investigated the phonetic representation of boundary tones in Persian declarative and interrogative utterances. Speech samples of the study were selected from Persian speech database, i.e., FARSDAT. These samples were produced by adult Persian speakers ranged in age from 20 to 45 years. PRAAT software was used for measuring the variation of F0 per millisecond at boundary tones. For investigating the phonetic representation of declarative sentences, a group of ten men and ten women were selected and each speaker produced 10 declarative utterances. Another group of ten men and ten women were selected for the investigation of phonetic representation of boundary tones in interrogative utterances. Each participant produced a yes-no question and a wh-question. Statistical analysis revealed significant difference (p< 0.05) between men and women regarding the variation of F0 at the boundary tones of declarative sentences and wh-questions. F0 was observed to fall faster at the boundary tones of declarative sentences and wh-questions produced by women. However, there was no statistically significant difference between men and women for variation of F0 at the boundary tones of yes-no questions. Results could be applied in speech recognition, text-to-speech synthesis, and other areas of speech processing.
The acoustics of charismatic voices in Korean political speech: A cross-gender study
Authors: Rhee Nari , Signorello Rosario
Published: May 2016

A previous study (JASA 136(4), 2295) investigated cross-cultural (Italian, French, and Brazilian) acoustic voice profiles in political speech to discern innate versus learned factors underlying the acoustics of charismatic voices. To further extend the study to other cultures and to both genders the present study investigates how Korean leaders manipulate their voices to exhibit charisma. The voice acoustic profiles of South Korean female (Geun-hye Park) and male (Jae-in Moon) politicians were analyzed. Results support previous findings showing a significant cross-culture and cross-gender similarity in communication context-specific (political campaign monologue, political peers-addressed speech, and non-political interview) use of voice F0 and SPL ranges. Data also confirm significant cross-gender differences in speakers’ F0 average frequencies (higher for the female speaker) within communication contexts. Finally, results confirm speaker-specific manipulations of F0 and SPL over time. The cross-cultural similarities in charismatic voice showed by the data support our hypothesis of several ongoing cross-cultural/gender processes of integration among some innate and cultural/linguistic vocal habits to convey leadership status: leaders estimate audience’s biological and social traits, manipulate vocal ranges of F0 and SPL accordingly, while maintaining women’s and men’s particular acoustic average features of F0 and SPL significantly different. [Work supported by NIH grant DC01797.]
The effect of structural context on phonetic accommodation
Authors: Manker Jonathan T.
Published: May 2016

Phonetic accommodation is a linguistic phenomenon whereby phonetic characteristics of one’s speech are influenced by perceiving the speech of others. The last decade has seen a multitude of studies which have induced the phenomenon in a lab setting, considering the social environments necessary for facilitating or inhibiting it. No studies, however, have investigated how the perception and production of speech in different structural contexts affects phonetic accommodation. This presentation analyzes the results of an experiment that compared the frequency of phonetic accommodation in three speech settings. In condition one, subjects read aloud and shadowed entire sentences which contained artificially lengthened VOT. In condition two, subjects read short phrases and shadowed sentences, and in condition three, both read and shadowed phrases. Our results showed that speakers accommodated lengthened VOT but often also showed modified burst intensities, suggesting imprecise accommodation. More accurate VOT accommodation was observed in conditions 2 and 3 (9/12 subjects for both) compared to condition 1 (5/12 subjects). “Inaccurate” burst accommodation was more common in condition 1 (8/12) and 2 (8/12) compared to condition 3 (4/12). The results suggest that higher levels of syntactic and semantic processing (both in production and perception) may impede processing of phonetic details.
Time dose and fundamental frequency of male and female speakers in different style and reverberation times
Authors: Bottalico Pasquale , Hunter Eric J. , Hunter Eric J.
Published: May 2016

Speakers adjust their vocal production when communicating in different room acoustics, when instructed to speak at different volumes and when experiencing vocal fatigue. The present paper reports on the effects of speech style, reverberation time, and external auditory feedback on time dose and fundamental frequency. Ten male and ten female subjects were recorded while reading a text in normal and loud styles, in three rooms—anechoic, semi-reverberant, and reverberant—and with and without acrylic glass panels at 0.5 m from the mouth, which increased external auditory feedback. Longer time doses were accumulated in more reverberant rooms, especially when loud voice was used. Higher fundamental frequency was measured in less reverberant rooms. Subjects increased their fundamental frequency in the loud speech style versus the normal style, but this effect was weaker when the level of external auditory feedback was high. A larger fundamental frequency range was detected for females than males and for the loud style than the normal style. These results contribute to understanding how the effect of room acoustics on speech changes as a function of speaking time.
Development of a system for in situ measurements of geoacoustic properties during sediment coring
Authors: Ballard Megan S. , Lee Kevin M. , McNeese Andrew R. , Wilson Preston S.
Published: May 2016

Sediment cores provide valuable insight on the physical properties of the seabed, and laboratory measurements of sediment wave speed from cores are often considered “ground truth.” However, sound-speed estimates obtained from cores can be inaccurate due to changes in pressure, temperature, and mechanical properties of the sediment caused by removal of the core from the seabed and its subsequent transport to the laboratory. To begin to address this deficiency, we report on the development of a system for obtaining in situ measurements of geoacoustic properties. The system mounts on the nose of a coring barrel to obtain an in situ record of compressional and shear wave speed and attenuation as the core penetrates the seabed. The depth of the in situ record is limited only by the penetration of the core. The compressional wave measurements are obtained with rod-mounted piezoelectric cylinders, and the shear wave measurements are obtained with bender elements mounted in flat blades. For both the compressional and shear wave measurements, wave speed and attenuation are estimated from differential measurements made with two receivers. [Work supported by ONR.]
Hope in mirrors: Update on using SketchUp and light rendering to visualize acoustic reflections
Authors: Carter J. Parkman
Published: May 2016

At a previous ASA meeting, a method was shown that allows architects to visualize acoustics in an intuitive manner using tools already familiar in the design workflow. The method is based upon some of the earliest forms of acoustics modeling, whereby mirror surfaces and light sources were used in scale models to determine the architecture’s impact on early reflections (a physical modeling of the image source method, essentially). This talk will demonstrate applications using this revitalized method, as well as expand on the original method using 360-degree immersive imagery, animating discrete reflection orders spatially (as opposed to temporally), and other useful techniques which are afforded by virtual modeling that would never otherwise be permitted by natural physics.
Underwater sound radiation from subsea factories
Authors: Binnerts Bas , Beek Pieter v.
Published: May 2016

In the Oil & Gas industry, there is a trend toward more subsea activities such as the processing of the Oil and Gas in so-called “subsea factories.” In this work, an overview is presented of the various anthropogenic sources contributing to the soundscape during the operational phase of these factories. With the measured sound spectrum (in air) of a complete turbo compressor installation and the known differences between radiation into air and sea water, a stylized, equivalent monopole source level is constructed. This source level is put into perspective by comparing it against a variety of other anthropogenic continuous sources. For a stylized subsea factory, it was judged that the turbo compressor will dominate the generated sound field of subsea factories. Finally, potential risks of the radiated sound are identified and possible sound mitigation solutions are discussed.
Underwater sound signatures of offshore industrial operations
Authors: Erbe Christine , Allen Kim , Duncan Alec , Gavrilov Alexander , McCauley Robert , Parnum Iain , Parsons Miles , Salgado-Kent Chandra
Published: May 2016

Marine industries, such as offshore petroleum, minerals, fisheries, transportation, tourism, defence, etc., introduce sound underwater, changing marine soundscapes, ranging from shallow coastal to deeper offshore regions. Concern about potential noise impacts on marine fauna has led to numerous underwater recordings and bioacoustic studies. Prior to operations, e.g., as part of permit applications for marine operations, environmental impact assessments are carried out that rely on the modelling and prediction of sound emission, propagation, and impacts. A catalog of sound signatures from activities ranging from exploration and surveying to construction, production, general operation, and decommissioning is necessary for predictive modeling. Underwater sounds recorded from seismic airguns, sub-bottom profilers, echosounders and sonars (sidescan, single-beam, and multi-beam), marine traffic (from small boats to large ships), aerial transportation (helicopters recorded underwater), dredging, pile driving, explosions, drilling, floating petroleum production, storage facilities, etc., are reviewed and their spectral and temporal characteristics, as well as beam patterns are discussed.
Marine soundscape during a shallow-water seismic survey in the Arctic Ocean
Authors: Guan Shane , Vignola Joseph F.
Published: May 2016

For noise generating activity that lasts for an extended period of time, an overall increase in noise levels and change of soundscape within a larger area (over tens of km2) can be expected. This study analyzed the sound field characteristics during a shallow-water marine seismic survey in the Beaufort Sea of the Arctic Ocean. Three bottom mounted acoustic sensors were deployed in the survey area: two outside the barrier islands in water depths about 12 m, and one inside the barrier islands in water depth of 2.8 m. Averaged 1 min sound pressure levels (SPLs) in broadband, 100–500 Hz, 1–5 kHz, and above 10 kHz bands were computed for periods when airguns were active and inactive. The results showed an 8-dB increase during the period when airguns were active in the 100–500 Hz band for two locations outside the barrier islands. However, there was no noticeable difference in SPLs during periods airguns were active and inactive inside the barrier islands. This is probably due to higher natural ambient noise and low-frequency cut-off of airgun pulses in this extreme shallow location.
Comparing methods for estimating the injury and behavioral disturbance radii from sound source characterization measurements
Authors: Martin Bruce , MacDonnell Jeff , MacGillivray Alexander O. , Hannay David
Published: May 2016

It is a common practice for regulators to require project proponents to estimate the radius around a sound source where marine life could be injured or disturbed. Acoustic propagation modeling is normally required so that realistic radii are obtained that take into account the bathymetry, bottom properties, water column sound velocity profile, as well as source spectrum and directivity. Increasingly proponents are also asked to perform in-situ sound source characterization (SSC) measurements to verify the modeling predictions, including the spectrum and directivity of the sound source. During an SSC, sound levels are measured at increasing range from the source. In most cases, it is not possible to measure the sound levels at all ranges of interest, and therefore, the data must be interpolated or extrapolated to estimate the radii of the regulatory sound isopleths. This talk uses real-world data to identify the strengths and weaknesses of four methods of estimating the radii: (1) the practical spreading model; (2) linear interpolation; (3) linear regression with absorption; and (4) model-measured fits.
Threshold of hearing versus threshold of sensation for low frequency and infrasound
Authors: Cooper Steven E.
Published: May 2016

Residents impacted by wind farms identify the perception of a sensation not necessarily noise. By use of a pressure sound field in a damped reverberation chamber the Threshold of Hearing for Infrasound and Low Frequency (refer Wattanbe and Moller) has been explored together with the Threshold of Sensation for sine waves. Those results are then compared using band limited pulsed signals from a Wind Farm. The differences and what they mean for Wind Turbine investigations are discussed.
Reproducing wind farm infrasound for subjective testingJust how accurate is the reproduced signal?
Authors: Cooper Steven E.
Published: May 2016

Apparently on the basis of room modes being excited in residential dwellings, one concept has been to ignore high quality field measurement recordings (wave files) and use the narrow band (FFT) Leq results of a 10 min sample to create, by superimposing a number of sine waves, a trapezoidal time signal as the source for subjective testing and restricting the bandwidth to only infrasound. Other testing utilizes full spectrum signals but has limitations on having an accurate signal due to the limitation of the speakers. An examination of both methods and the limitations of the results have been examined and will be discussed.
Full transmission and reflection of waves propagating through a maze of disorder
Authors: Gérardin Benoît , Laurent Jérôme , Derode Arnaud , Prada Claire , Aubry Alexandre
Published: May 2016

Multiple scattering of waves in disordered media is often seen as a nightmare whether it be for communication, imaging, or focusing purposes. The ability to control wave propagation through scattering media is thus of fundamental interest in many domains of wave physics, ranging from optics or acoustics to medical imaging or telecommunications. Thirty years ago, it was shown theoretically that a properly designed combination of incident waves could be fully transmitted through (or reflected by) a disordered medium. Although this remarkable prediction has attracted a great deal of attention, open and closed channels have never been accessed experimentally. Here, we study the propagation of elastic waves through a disordered elastic waveguide. Thereby, we present experimental measurements of the full S-matrix across a disordered elastic wave guide. To that aim, laser-ultrasonic techniques have been used in order to obtain a satisfying spatial sampling of the field at the input and output of the scattering medium. The unitarity of the S-matrix is investigated and the eigenvalues of the transmission matrix are shown to follow the expected bimodal distribution. Full transmission and reflection of waves propagating through disorder are obtained for the first time experimentally. The wave-fields associated to these open and closed channels are imaged within the scattering medium to highlight the interference effects operating in each case.
Stochastic theory for multiple scattering of ultrasound in particulate media
Authors: Alba Felix
Published: May 2016

Even though there have been published/used several approaches to modeling the complex phenomenon of multiple scattering, they are either of a semi-empirical nature with severe limitations in size/wavelength range and performance or, albeit having a fundamental flavor, have proven not accurate enough to be employed in broad range/application scientific instruments. Fundamental versus phenomenological approaches are discussed. The METAMODEL™ fundamental multiple-scattering theory is as fundamental as Mie (optics) and ECAH (acoustics) single-scattering theories. Besides its fundamental character, its generic validity resides in having described and calculated the detailed interaction between the scattered fields produced by every particle, treating such an interaction in a statistical sense and leading to generic stochastic field equations where the overlapping of all scattered fields is equally contemplated regardless of their physical nature (viscous-inertial, thermal diffusion, elastic, electromagnetic, etc.). The fundamentals of this theory are described in some mathematical detail. Using the Ultra-SCATTERER™ R & D software tool, predicted as well as experimental data in concentrated suspensions, emulsions, and aerosols (collected with commercially available spectrometers) are presented.
Acoustic propagation and multiple scattering in powders
Authors: Povey Malcolm J. , Holmes Mel , Al-Lashi Raied
Published: May 2016

Determination of the material properties of powders is critical in very many industries yet crucial transformations such as the transition from a free-flowing powder to a caked powder defy quantitative measurement. In particular, distinguishing between the onset of caking (so that it may be prevented, for example) and consolidation or segregation of powders which have not caked is very difficult. We present here calculations of the acoustic properties of free flowing powders based on scattering theory (Alba, 2004), together with model calculations for caked and consolidated powders within which an effective stiffness has developed (Coghill 2011, Makse 2004). These calculated values are compared with the measured acoustic properties of silica powders demonstrating that acoustic measures such as the velocity of sound and the attenuation of sound (insertion loss) are highly effective in distinguishing between caking and consolidation. Alba. 2004, Chapter 10 of “Concentrated dispersions, theory, experiments, and applications,“ edited by P. Somasundaran and B. Markovic, American Chemical Society (ACS) Symposium Series 878. Coghill and Giang, Powder Technol. 208, 694–701, 2011. doi:10.1016/j.powtec.2010.11.040. http://dx.doi.org/10.1016/j.powtec.2010.11.040. Makse, Gland, Johnson, and Schwartz, Phys. Rev. E70, 1–19, 2004. doi:10.1103/PhysRevE.70.061302.
Nonlinear acoustic forces acting on inhomogeneous fluids at slow time-scales
Authors: Karlsen Jonas T. , Augustsson Per , Bruus Henrik
Published: May 2016

We present a novel theory describing the nonlinear acoustic force density acting on a fluid of inhomogeneous density and compressibility, for example, due to an added salt concentration. We derive an expression for the time-averaged acoustic force density acting on an inhomogeneous fluid, which depends on the gradients of the fluid density and compressibility. This smeared-out force density can be interpreted as a generalization of the well-known acoustic forces acting on a particle or an immiscible-fluid interface. The special case where the speed of sound in the solution is independent of the salt concentration, which is a good approximation for many actual salt solutions, leads to a particularly simple theoretical description. The theory predicts that in microfluidic channels, the nonlinear acoustic forces act to relocate density distributions into field-dependent configurations, which are stabilized against gravitational collapse driven by hydrostatic pressure gradients. We show the first experimental confirmations of these predictions obtained by confocal imaging in glass-silicon microchips.
Multiple scattering in bubbly media: Highlighting the role played by interactions between neighboring bubbles
Authors: Lanoy Maxime , Leroy Valentin , Tourin Arnaud
Published: May 2016

A bubble in water exhibits a low-frequency monopolar acoustic resonance, the so-called Minnaert resonance, which makes an assembly of such bubbles an ideal system to study multiple scattering of ultrasound. Following Foldy’s seminal work, various approaches, such as the ones by Keller or Waterman and Truell, have been developed to infer the effective acoustic properties of a bubble cloud. Here, we confront the predictions of these different approaches with numerical results obtained with a multiple scattering theory (MST) code that fully incorporates the multiple scattering effects. Based on this study, we show the importance to take into account the interactions between neighboring bubbles to predict the behavior of a bubble sample. Finally, we demonstrate how the introduction of a local order can affect the effective parameters and allows interesting transmission properties.
Nonstructural acousto-injection luminescence in metalized lithium niobate
Authors: Ostrovskii Igor , Korotchenkov Oleg , Borovoy Nikolaj , Nadtochiy Andriy , Chupryna Roman , Chatterjee Chandrima
Published: May 2016

The observation of a nonstructural acousto-injection luminescence (NAIL) from metallized LiNbO3 wafers is reported. The X- and Y-cut plates with linear dimensions of a few mm and silver paste electrodes on opposite surfaces are investigated. The experiments are done at room temperature. The fundamental shear modes are excited at MHz-frequencies. We measure the spectra of NAIL, acousto-electric resonance/antiresonance properties, X-ray diffraction rocking curves, acoustic emission accompanying NAIL, and photoluminescence. The NAIL and associated effects appear above a certain threshold acoustical strain of e = 10-5. The results are explained in the terms of considerable piezoelectric fields, yielding the charge injection from the metal contacts into crystal along with the strong mechanical stresses leading to dislocations motion. The acoustic emission and X-Ray rocking curves disclose the dislocation motion under e > 10-5. The involvement of the microstructural non-uniformities in the effects observed is experimentally identified by the X-ray rocking curves taken at different ultrasound amplitudes and photo-luminescence spectra taken from the different micro-regions of samples. Photoluminescence reveals the charged point defects that may promote an electrical conduction. The distribution of crystal defects along wafers is not uniform, and has a quasi-periodical component with tens to hundreds of microns spacing between their extremal locations.
Cues in detection of rhythmic irregularities
Authors: Wojtczak Magdalena , Oxenham Andrew J.
Published: May 2016

A recent study [Hove et al. (2014). Proc. Natl. Acad. Sci. 111, 10383–10388] showed that the perception of rhythm carried by simultaneously presented low-pitch and high-pitch complex tones is more easily disrupted by timing irregularities in the low tone than in the high tone. This result led the authors to conclude that low-pitch tones are used for laying down the rhythm in music because they are more precise rhythmic time markers than high-pitch tones. In this study, no difference was found in the temporal acuity for low and high tones. Instead, asynchrony detection was found to be better for low-leading than for high-leading tone pairs, regardless of which tone was rhythmically irregular in a sequence. The results are consistent with an asymmetry in the perception of asynchrony between a low and high tone pair without the rhythmic context [Wojtczak et al. (2012). J. Acoust. Soc. Am. 131, 363–377]. The outcome leads to a reinterpretation of the results of Hove et al., based on asynchrony, rather than rhythm, perception. Possible ecological reasons for the asymmetry in asynchrony perception include the natural properties of both sound sources and the peripheral auditory system. [Work supported by NIH grant R01 DC005216.]
The role of a temporal mechanism in the perception of speech-like logarithmic frequency sweeps
Authors: McClaskey Carolyn M. , Cramer Daniel , Saberi Kourosh
Published: May 2016

The auditory system is thought to process dynamic changes in frequency via two complementary mechanisms: a phase-locking-based mechanism that is limited to slowly changing stimuli at low (<4–5 kHz) frequencies, and an energy-based mechanism that functions across all frequency regions and all rates of change. The current study investigates the relative contribution of these two mechanisms—and the role of phase-locking cues in particular—in the perception of low, slow frequency sweeps that closely parallel those found in speech prosody. Listeners identified the direction of unidirectional logarithmic frequency sweeps in a single-interval identification task. Both the rate and extent of frequency change (i.e. transition span) were uniformly varied over a range of 0.0147–0.1667 octaves/s and 0.1–0.5 semitones, respectively. Stimuli were roved around a center frequency of 500 Hz, and all were between 50 and 1000 ms in length. Results show that sensitivity (d') significantly increases with increasing transition span but significantly decreases with increasing rate of frequency change, suggesting that phase-locking cues may contribute to the perception of sweeps with very slow rates of change. Data were well-predicted by a multivariate linear model as a joint function of sweep rate and transition span.
Limitations on temporal processing by cochlear implant users
Authors: Carlyon Robert P. , Cosentino Stefano , Deeks John M. , Parkinson Wendy , Bierer Julie A.
Published: May 2016

Two experiments studied the deterioration in rate discrimination and pitch perception for pulse trains presented to single electrodes at high pulse rates. The first measured rate discrimination DLs (“RDLs”) for 100-pps and 400-pps standard rates, for each of 4–5 electrodes and for 10 Advanced Bionics cochlear implant users. Thresholds were measured using two interleaved adaptive tracks, corresponding to the 100- and 400-pps standard rates. Gap detection thresholds (“GDTs”) for a 1031-pps pulse train were also measured. There was a highly significant across-subject correlation between GDT and the 400-pps but not the 100-pps RDL, and these two correlations differed significantly from each other. Similarly, the across-electrode correlation between GDT and the 400-pps RDL was marginally significant, whereas there was no correlation between GDT and the 100-pps RDL. These findings are consistent with the deterioration in high-rate temporal processing sharing a common basis with the mechanisms involved in gap detection, but not with the limitations in low-rate temporal processing. We will also report the results of a second experiment that measured rate discrimination and pitch ranking at low and high rates, both on the same day that patients’ implants were activated and after two months of listening experience.
Backward masking determination with simultaneous early, middle, and late evoked potentials
Authors: Smith Silas , Sears Robert , Yonovitz Al
Published: May 2016

Backward masking (BM) functions have been shown to relate to age, lead toxicity, and are differentiated in children with language disorders. These functions may be indicative of auditory processing deficits. This study investigated if evoked potentials (EP) could be utilized to obtain BM functions. A tonal stimulus, followed by an ISI and a noise masker was the EP stimulus. All were studied individually in the appropriate temporal alignment. The design of this study allowed observation of the early, middle, and late auditory evoked potentials. This study randomly presented four different stimulus conditions: (1) tone alone, (2) noise alone, (3) tone and noise, and (4) silence. With a long inter-trial interval (1 s) and high sample rate (25 600 Hz) EP’s were obtained for 4000 trials. The stimuli were pure-tones (1000 Hz, 10 ms duration with a Blackman function and noise bursts of varying intensity and varied ISI. Results indicated that EP’s could be arithmetically combined to observe the differential electrophysiological responses and neurologic loci of evoked potentials during the BM effect.
The inter-stimulus interval critical value in backward masking testing
Authors: Sears Robert , Smith Silas , Schied Sarah , Yonovitz Al
Published: May 2016

Backward masking (BM) has been studied both as a psychoacoustic phenomenon and as a potential diagnostic indicator of auditory processing difficulty. In BM assessment, the subject responds to a brief tonal signal followed by an inter-stimulus interval (ISI) of silence and then by a noise masker. In all previous studies, an adaptive auditory threshold is obtained at each ISI. This study used unique instrumentation that allowed the adaptive ISI to maintain threshold. Twelve subjects were utilized. All had normal hearing with an age range of 18–30 years. The critical ISI was varied with an adaptive procedure in 2 ms steps. The critical ISI value was obtained for stimulus intensity levels above the tonal threshold found in a longer ISI condition. This procedure allowed less fatigue and provided an easier task for the subject compared to the tonal intensity tracking task.
Discrimination thresholds for level increments in the stop-consonant noise bursts of CVC words: Intra-speech masking, temporal-position, temporal-variability, and place-of-articulation effects
Authors: Espinoza-Varas Blas , Hilton Jaremiah
Published: May 2016

Estimates of sensitivity to level differences in stop-consonant noise bursts could help designing speech-processing strategies such as dynamic-range compression and optimal consonant-vowel intensity ratio. In normal-hearing participants, we measured level-discrimination thresholds (LDTs) for the noise bursts of CVC words (/pæt/, /pæk/, and /kæt/). With /pæt/, a 2I-2AFC task measured LDTs for the pre- or post-vocalic burst in isolation or in word context; in the latter, the burst with level increments (pre or post) remained the same or varied unpredictably from trial to trial. In isolation, the 1.98–2.22 dB LDTs approached those of like-duration random noise, but increased to ≈9.0 dB for the pre-vocalic burst in-context, and more so in unpredictable-burst conditions (10.81 dB); for the post-vocalic burst the LDTs increased only slightly. To assess the role of set-size, within-trial standard, and place-of-articulation, the in-context, unpredictable-burst LDTs were measured with single- or two-observation interval 2AFC tasks presenting only /pæt/ or, randomly, /pæt/, /pæk/, or /kæt/. The context, temporal-position, predictability, and place-of-articulation effects were significant but those of within-trial standard and set size were not; for pre-vocalic bursts, LDTs were much higher (9.97 dB) for the velar than the labial consonant (4.78 dB).
Sound recognition depends on real-world sound level
Authors: Norman-Haignere Sam V. , McDermott Josh H.
Published: May 2016

How does the auditory system recognize instances of the same sound class with distinct acoustic properties? As a case study, we investigated the recognition of environmental sounds at different levels. In principle, level-invariant recognition could be achieved by a normalization mechanism that removes variation in level from listeners’ representation of sound identity. Alternatively, listeners could use level as a cue to aid their recognition, taking advantage of the fact that different sound classes are typically heard at different levels. The latter hypothesis predicts that sounds heard at atypical levels should be more difficult to recognize. We tested this prediction by asking human listeners to identify 300 environmental sounds, each presented at seven different sound levels between 30 and 90 dB SPL. We grouped these 300 sounds into those typically heard at low (e.g. salt-shaker) and high sound levels (e.g., jackhammer) using ratings collected via Mechanical Turk. For typically loud sounds, recognition accuracy improved monotonically with increasing experiment level. But for typically quiet sounds, recognition accuracy declined at high experiment levels (above 60 dB). These results are consistent with the hypothesis that listeners recognize individual sounds by internalizing the unique distribution of acoustic features that characterize them.
Evaluating whether increment detection at mid-to-high pedestal frequencies is consistent with cochlear compression
Authors: Chen Jessica , Jennings Skyler G.
Published: May 2016

The ability of the auditory system to encode the amplitude fluctuations of a signal is important for processing complex stimuli, such as speech. A study by Florentine [Florentine et al., J. Acoust. Soc. Am. 81, 1528–1541 (1987)] measured intensity discrimination for multiple frequencies as a function of stimulus level. They observed that, for high frequency stimuli, difference limens were poorer at mid levels than at higher or lower levels. This mid-level “hump” is consistent with cochlear compression and suggests that compression may limit the intensity resolution of the auditory system under certain circumstances. To test the generalizability of this interpretation, the current study measured increment detection for conditions associated with the mid-level hump, based on the assumption that increment detection and intensity discrimination are determined by similar physiological processes. This study is part of a larger series of experiments in our laboratory that test whether intensity perception is consistent with peripheral processes such as cochlear compression and efferent-mediated regulation of cochlear amplifier gain.
Vibration isolation for concert hall next to busy street
Authors: Phillips James E.
Published: May 2016

A new, world-class performing arts center is currently being developed in a metropolitan center in the United States. The center will include two grand performance theaters. One of these theaters will be located close to a busy surface street. Vibration measurements conducted at the undeveloped site indicated that groundborne noise from street traffic would be audible within the completed theater unless measures were incorporated into the design to reduce vibration transmitted from the street to the interior of the theater. This will be achieved by structurally separating the performance area of the theater from the surrounding structure by supporting the theater on custom designed, resilient bearing pads. This paper discusses the vibration measurements taken, the projections of groundborne noise and the vibration mitigation measures that were incorporated into the structural design of the theater building to reduce groundborne noise to meet the project design criteria for background noise.
Use of language-specific speech cues in highly proficient second-language listening
Authors: Cutler Anne , Bruggeman Laurence , Wagner Anita
Published: May 2016

Language-specificity in listening to speech occurs at all processing levels and even between structurally close languages (e.g., English, Dutch). Transitional cues to fricative place of articulation are used in English for identifying /f/ (which resembles theta) but not /s/, whereas in Dutch (without theta) they are used for neither. In spoken-word recognition, suprasegmental cues are used in Dutch, but not in English (with more segmental reduction); Dutch L2 listeners even outperform native L1 listeners in detecting origin of differently stressed English syllables (e.g., car- from CARton versus carTOON). Here, longterm residents in Australia with Dutch as L1 but predominantly using English completed each of these tasks. In the phonetic task, with cross-spliced nonsense words, these listeners performed just as Dutch listeners in the Netherlands, showing insensitivity to transitional cues for both /f/ and /s/. In the lexical task, with word fragments (e.g., car-), they however did not behave as L1 Dutch and outperform Australian English listeners, but instead resembled the latter, by ignoring suprasegmental stress cues. A (lexical) listening strategy available in L1 can apparently be abandoned if it delivers little payoff in L2, but acquiring for L2 listening a (phonetic) strategy not used in L1 seems less feasible.
Recognition memory for foreign- and native-accented sentences
Authors: Van Engen Kristin , Peelle Jonathan
Published: May 2016

The acoustic-phonetic properties of speech signals affect not only their intelligibility, but also how well they are encoded in memory. Recognition memory can be improved, for example, when speakers intentionally speak clearly (Van Engen et al., 2012). One explanation for this result is that enhanced acoustic-phonetic cues reduce the cognitive effort associated with perceptual speech processing, thereby increasing the availability of processing resources for encoding speech content in memory. In the current study, we tested the hypothesis that, following the same logic, recognition memory would be reduced for foreign-accented speech, in which acoustic-phonetic cues deviate from native-language norms. Participants heard English sentences produced by a native speaker of English and a native speaker of Korean. Recognition memory was tested using an old-new judgment task in which participants heard those recordings again, along with an equal number of new items. Surprisingly, recognition memory was higher for Korean-accented English than for native-accented English. A follow-up study in which test sentences were presented visually showed no difference between foreign- and native-accented speech. These results are consistent with an acoustic distinctiveness account in which foreign-accented speech can in some cases be remembered more accurately due to its distinct acoustic features.
Transitioning learning strategies in speech categorization enhances lexical learning
Authors: Yi Han-Gyol , Tessmer Rachel , Chandrasekaran Bharath
Published: May 2016

A recent model suggests two strategies are involved in speech category learning: a reflective strategy that maps sounds onto categorical representations explicitly, and a reflexive strategy that does so implicitly. Successful learners transition from an initial reflective strategy to a reflexive strategy. We examined the extent to which speech category learning in adults can be improved by selectively enhancing these strategies in an optimal sequence, and how this influences performance in a lexical learning task. Monolingual English speakers (N = 40) learned to categorize Mandarin tones. Participants in the “optimal” condition (n = 10) were first presented with a combination of feedback information and talker presentation designed to enhance reflective strategies, and later presented with a feedback-talker combination that targeted reflexive strategies. This order was reversed in the “sub-optimal” condition (n = 10). Two control conditions (n = 10 each) exclusively targeted either strategy. All participants then learned 24 pseudo-Mandarin lexical items across three days. Participants in the optimal condition outperformed those in the sub-optimal and control conditions on the lexical learning task despite the fact that they did not attain the highest speech categorization accuracy. These results suggest that transitioning from reflective to reflexive strategies is ideal for applying learned speech categories to novel words.
Modal wavenumber estimation using a Bayesian compressed sensing algorithm
Authors: Dremeau Angelique , Bonnel Julien , Le Courtois Florent
Published: May 2016

In shallow water, low-frequency acoustic propagation is described by modal theory. In this context, the environment acts as a dispersive waveguide, and the geoacoustic properties of the seabed can be inferred from the modal wavenumbers. When considering horizontal aperture (using a horizontal array or a towed source), wavenumber estimation is a well-known problem, equivalent to spectral analysis. In this paper, wavenumber estimation is revisited using Compressed Sensing (CS). Our method benefits from two strong physical hypotheses. Only a few modes are propagating so that the wavenumber spectrum is sparse. Moreover, if the source is broadband, the wavenumbers can be related from one frequency to the next using a general dispersion relationship. Our method resorts to a state-of-the-art Bayesian algorithm exploiting a Bernoulli-Gaussian model. The latter, well-suited to the sparse representations, makes possible a natural integration of the prior dispersion information through a wise choice of the Bernoulli parameters. The whole methodology is assessed on simulated data and successfully applied on marine data.
Spatial variability of seabed properties on the Malta Plateau inferred with an autonomous underwater vehicle
Authors: Dettmer Jan , Holland Charles W. , Dosso Stan E. , Quijano Jorge E. , Mandolesi Eric
Published: May 2016

We develop an automated method to infer geoacoustic properties along tracks surveyed by autonomous underwater vehicles (AUVs). The AUV tows a 32-element receiver array and a source emitting signals (“pings”) at regular intervals. Recordings are processed in terms of reflection coefficients, resulting in large data volumes with substantively more information on seabed structure than traditional seismic profiling. However, interpreting seabed spatial variability requires efficient inversion. The inverse problem is non-linear and requires Bayesian sampling to quantify parameter uncertainties. To account for changes in the number of seabed layers at each ping position, the parametrization treats this number as unknown with a Poisson prior and even-numbered order statistics to improve efficiency. The method is applied to 340 data sets along a 14-km track on the Malta Plateau, employing 8 graphics processing units for approximately 2 weeks of computing time. The results resolve layering along the track with previously unreported detail. An erosional boundary is clearly resolved as a high-velocity, high-density layer and appears rougher and is buried deeper in shallower water. Depressions along this boundary are filled in with lower-velocity material. In addition, sound attenuation is well constrained in a thick low-velocity wedge. [Work supported by ONR and SERDP.]
Effects of seabed curvature on the scattered acoustic field
Authors: Martinelli Sheri , Holland Charles
Published: May 2016

Knowledge of the acoustic properties of the sea bottom provides valuable input into the development and performance of information processing algorithms designed to detect and identify, e.g., man-made objects near to, or embedded in, the seabed. This information is also useful for improving modeling and simulation results in reverberation-limited environments. A critical challenge in this area is in allowing for range dependent bathymetry as it can affect the propagating acoustic field in ways that are difficult to predict. Typical approaches to modeling variable bathymetry assume either piecewise flat or tilted (linear) geometry; however, this only serves as a discrete approximation to reality. This study investigates the effects of mild curvature on the 3D acoustic field in frequency and angle space via finite difference time domain simulations. We present results and discuss the implications on forward modeling of the acoustic interaction with the seabed. [Work supported by the Strategic Environmental Research and Development Program (SERDP).]