bluuebunny/crossref_metadata_2025 huggingface dataset:
Case studies and installation data on the acoustical properties of a new class of translucent, lightweight insulation material from NASA called aerogel.
Authors: Satterwhite James
Published: October 2013

Aerogels are well-known as a class of thermal insulation with “green” benefits including translucence, hydrophobicity, and light weight. However, before 2008, the acoustical properties of aerogels had not been characterized. Used by NASA in the 1970s, aerogels became available in the 1990s as insulation for the construction industry in skylights, underwater pipelining, and roofing fabric. In 2008, laboratory testing and field research began on the acoustical properties of thin profile (2–8 mm) architectural “tensile membrane” fabrics incorporating silica aerogel granules. Data from a tension structure in Vancouver—where aerogel-enhanced fabric was used to block aircraft noise—exhibited excellent acoustic absorption and acoustic impedance matching properties compared to insulators of comparable thickness. In this installation the material increased transmission loss of exterior to interior noise, and reduced indoor reverberation. Also in 2008, U.S. field tests demonstrated an aerogel blanket material as a surface treatment in offices to reduce broadband reverberation, resulting in increased speech intelligibility and enhanced acoustical comfort (an important factor in the 2009 LEED rating system). The acoustical attributes—combined with aerogel’s thermal value, thin form factor, translucence, hydrophobicity, light weight, and absence of VOCs has led to growing interest in applications ranging from aircraft interiors to hospitals.
Sustainablity and noise: An exploration of perception of noise as a significant component in sustainable design in a variety of cities internationally.
Authors: Gerlsbeck Andreas , van Orden Paul
Published: October 2013

The current acceptance in the sustainability design field of noise and acoustics as a holistically related design concern to the overarching discipline varies widely around the world. The authors’ unique experiences on different continents help in the exploration of the current state of the acceptance of acoustical engineering in the sustainability field. An exploration of the paper from F. D. Henry [F. D. Henry, Proc. 8th International Congress on Noise as a Public Health Problem (2003)] is taken into account. The authors place notable focus on review of the efforts on the topic by several German research institutions such as: The German Federal Institute for Environmental Issues; The Federal Institute for Occupational Safety and Health; and The DEGA (The German Association of Acoustics). The authors expound on possible reasons why noise and acoustical design elements are often an afterthought by government development and environmental agencies, and design firms focused on sustainable design. The authors explore a number of suggestions for enabling forward movement toward increased inclusion of acoustical design in the sustainable design portions of future projects internationally.
Green building acoustics: Scoring user performance factors.
Authors: Sweitzer Glenn E.
Published: October 2013

Architectural acoustics lacks specificity in the LEED for Schools (2007), green building rating system, which is based on a checklist score. Uncorrected, this edition lacks the guidance needed to meet, consistently, the stated intent: to facilitate better teacher-to-student and student-to-student communications. An alternative system—user performance based—is developed for scoring speech transmission index (STI), and tested in K–5 elementary school classrooms. K–5 teachers are surveyed and then interviewed regarding sound and noise control strategies employed in their respective classrooms, by academic subject; AV media; and teacher/student configuration. Reported outcomes are compared with STI contours. The requisite background noise level and room impulse response measurements are made using a binaural acoustic mannequin at each listening position. It is expected that STI will vary among listening positions, and by academic subject and teacher/student configuration. Accordingly, scoring for the classroom will vary. Results are discussed, and based on the findings, passive means are suggested for improving STI in the classrooms studied.
Two challenges to achieving acoustical privacy in open offices: Going green in Switzerland.
Authors: Conant David A. , Chu William
Published: October 2013

An unusual human resources office building under construction in Basel, Switzerland presented several acoustical challenges stimulated by both the architect and owner. Extensive studies demonstrated that without electronic speech sound masking, normal privacy would likely be unachievable until the receiver moved at least one floor level away from the talker. Still, the owner opted to provide no accommodation for masking for reasons we have not encountered before. Novel designs arose for absorptive chilled beams including a glass roof with chilled beam baffles. The design approaches and RASTI modeling via CATT-Acoustic are described.
Determining underwater auditory thresholds in fish based on particle motion.
Authors: Hastings Mardi C.
Published: October 2013

Acoustic particle motion is believed to play a significant role in the auditory scene of fishes even though most all hearing sensitivity data are measured with respect to sound pressure level. Auditory motion thresholds have been measured in air for goldfish (Carassius auratus), oscars (Astronotus ocellatus), and toadfish (Opsanus tau) by moving the fish’s body using a carefully calibrated shaker table [R. R. Fay, Science 225, 951–954 (1984); Z. Lu, A. N. Popper and R. R. Fay, J. Comp. Physiol. A 179, 227–233 (1996); R. R. Fay and P. L. Edds-Walton, Hearing Res. 111, 1–21 (1997)]. These responses depend on both direction and amplitude of the motion. Thus, underwater particle motion thresholds must include both direction and amplitude, but most experimental setups are not designed for this purpose. Passive and active methods to control the direction and amplitude of acoustic particle motion underwater are presented. It is not enough just to measure the local particle motion in a small tank and report its amplitude as a threshold, especially when incidental sound pressure could be contributing to the auditory response and the orientation of the fish with respect to the direction of the particle motion vector is ill defined.
Sensitivity of utricular afferent fibers to intraspecific calling via inductive neural telemetry in free ranging oyster toadfish, Opsanus tau.
Authors: Mensinger Allen F. , Maruska Karen P.
Published: October 2013

Male toadfish acoustically attract females to nesting sites by producing boat-whistle calls. To determine how the fish localize sound underwater, inductive neural telemetry was used to record from microwire electrodes chronically implanted into the utricular nerve of the toadfish, Opsanus tau. The telemetry tag allowed both laboratory and field monitoring of unrestrained, naturally behaving fish. The sensitivity of utricular afferent nerve fibers to male toadfish boat whistle calls and pure tone stimulus was determined in water depths ranging from 0.4 to 1.0 m via underwater speakers. Hydrophones were placed approximately 5 cm above the otoliths to determine the physical characteristics of the sound impinging on the utricle. Approximately 75% of the afferent fibers exhibited increased firing to sound stimulus, with many showing directional sensitivity. Thus, toadfish may be able to use information from the utricular afferents to localize sound underwater. [Work supported by NSF Grant 0316130.]
Substrates for vocal-acoustic plasticity: Neuroestrogen and steroid hormone receptor expression in midshipman fish.
Authors: Forlano Paul , Marchaterre Margaret , Deitcher David , Bass Andrew
Published: October 2013

In a teleost fish, the midshipman Porichthys notatus, androgens and estrogen rapidly modulate vocal motor patterning and contribute to seasonal changes in the frequency encoding of the eighth nerve. To identify potential sites of action of these steroids, as well as local estrogen synthesis (via conversion from testosterone by the enzyme aromatase), in situ hybridization was employed to identify estrogen receptor alpha (ER), androgen receptor (AR), and aromatase mRNA distribution in vocal and auditory circuitry. AR expression was more widespread than ER and found at all levels of the vocal motor pathway and in vocal-acoustic integration centers, while aromatase was particularly abundant in the vocal motor system. Both AR and ER were identified in midbrain and forebrain auditory nuclei and in the saccular epithelium of the inner ear, the main auditory end organ in midshipman and most teleosts. Aromatase was found in ganglion nerve cells of the eighth nerve, suggesting that the ear itself is a local source of estrogen driving peripheral auditory plasticity. In sum, expression of steroid receptors in vocal and auditory nuclei, and the inner ear, support neurophysiological evidence for the role of estrogen and androgens as modulators of vocal output and auditory encoding in midshipman fish. [Work supported by NIMH, NIH, and NSF.]
Multisensory integration in the tadpole medulla arises from discrete and overlapping regions of endorgan projection.
Authors: Simmons Andrea M. , Flores Victoria , Horowitz Seth S.
Published: October 2013

Vestibular and auditory nuclei in the medulla are inherently multimodal in developing bullfrogs (Rana catesbeiana), responding to pressure, particle motion, and lateral line input. While brainstem and midbrain connectivity of these nuclei have been well mapped across metamorphic development, developmental changes in projection patterns from individual endorgans in the otic capsule (sacculus, utricle, lagena, and amphibian and basilar papilla) to the medulla are less well understood. Using small (26 nl) focal injections of neurobiotin in preganglionic branchlets for specific endorgans, we were able to map input from the separate peripheral organs to different medullary nuclei (medial, superior and lateral vestibular nuclei, the dorsal medullary nucleus, and the anterior lateral line nucleus). Some secondary trans-synaptic label of the reticular gray and cerebellum was also noted. Projection patterns are correlated with different patterns of medullary responses to vibratory and to pressure stimulation. Endorgan projection patterns appear relatively stable across metamorphic development. These data suggest that changes in functional response properties in the medulla across development do not reflect rewiring of inner ear input, but instead depend on changes in connectivity between the medullary nuclei and their more central target zones. [Work funded by NIDCD and the Rhode Island Space Grant Consortium.]
Passive remote sensing through cross-correlation of nondiffuse ambient noise.
Authors: Godin Oleg A.
Published: October 2013

Under rather restrictive assumptions about ambient noise field and its sources, it has been demonstrated theoretically by a number of authors that one can retrieve the exact acoustic Green’s function (GF) of an inhomogeneous medium from the noise cross-correlation function (NCCF). These assumptions are rarely valid for ambient noise in the ocean. In this paper, asymptotic approaches are used to investigate the information content of two-point correlation functions of ambient noise and their possible use for passive remote sensing of the environment under more general conditions, when there exists no simple, exact, local relation between NCCF and deterministic GFs. For noise sources distributed on a surface or in a volume of a moving or motionless, inhomogeneous fluid, a relation is established between contributions of ray arrivals to NCCF and GFs. A similar relation is derived for contributions to NCCF and GFs due to adiabatic normal modes in a horizontally inhomogeneous waveguide. The impact of nonuniformity of the spatial distribution of noise sources on accuracy of passive measurements of acoustic travel times is quantified. Effects of finite correlation length of noise sources on GF retrieval from ambient noise are discussed. [Work supported by ONR.]
Measurements of acoustic propagation with accompanying high-resolution sound speed structure containing internal waves.
Authors: Henyey Frank S. , Williams Kevin L. , Tang Dajun
Published: October 2013

During the Shallow Water 2006 experiment, simultaneous measurements were made of the sound speed structure associated with nonlinear internal waves and acoustic propagation at frequencies of 2–10 kHz over a 1 km path. The internal waves were measured by a towed CTD chain in order to get high resolution. These measurements were coordinated so that the nonlinear waves can be interpolated onto the acoustic path, allowing predictions of their effects on the acoustics. An internal wave train was measured that passed the acoustic path on August 13. When the wave train was in between the sound source and receiver, distinctive arrival time oscillations on three acoustic paths were measured, which are all rays having an upper turning point. Using the CTD chain data, a deterministic explanation is given to the arrival time oscillations.
Estimation of average acoustic concentration of Chinese hamster ovary cells using ultrasonic backscatter.
Authors: Song Jun , O’Brien William
Published: October 2013

Average acoustic concentration (AAC) is one important parameter of quantitative ultrasonic assessment of soft tissues. The objective of this study is to examine the AAC of Chinese hamster ovary (CHO) cells at varied cell densities using ultrasonic backscatter. The CHO cells were evenly distributed in 2% agar and the densities ranged from 500,000 to 54,000,000 cells/mL. Measurements of backscattered ultrasound were obtained over the frequency range of 17 to 80 MHz. Estimates of Average Scatterer Diameters and AAC were made by comparing the backscattered power spectra with three scattering models: Fluid-filled Sphere model (FFSM), Spherical Gaussian model (SGM), and Concentric Sphere Model (CSM). Over the frequency range of 28 to 50 MHz, the estimated ASDs were 20.0±0 μm with FFSM, 22.2±6.0 μm with SGM, and 20.1±6.1 μm with CSM. In the cell density range of 500,000 to 10,000,000 cells/mL, the estimated AACs increased almost linearly from 10 to 34 dB/mm3 using FFSM, from 16 to 39 dB/mm3 using SGM, and from 8 to 31 dB/mm3 using CSM. [Work supported by NIH Grant CA111289.]
Mammary tumor classification using envelope statistics from ultrasound backscatter and the homodyned K distribution.
Authors: Hruska David , O'Brien William D. , Oelze Michael
Published: October 2013

Envelope statistics from ultrasound backscatter based on the homodyned K distribution were used to characterize organizational patterns of tissue microstructure in three rodent models of breast cancer: a mouse mammary carcinoma, a mouse mammary sarcoma, and a rat fibroadenoma. The homodyned K distribution was used to model the amplitude of the envelope of backscattered ultrasound yielding two parameters to characterize tissues: one related to the effective scatterer density and the other related to periodicity of scatterer locations. Ten tumors of each of the three kinds of tumors were scanned. Envelope statistics model parameters were estimated for regions of interest measuring 1 × 1 mm in each of the tumor images. These estimates were then averaged together for each tumor. A linear combination of the two estimated parameters was derived for each tumor in order to obtain a lumped parameter for discriminating between the different kinds of tumors. This linear combination yielded the following (mean±SD): carcinomas 9.58±1.17, sarcomas 12.01±0.78, and fibroadenomas 11.66±1.15. These estimates were statistically significant in distinguishing carcinomas from sarcomas (p<0.05) and carcinomas from fibroadenomas (p<0.05), but a statistically significant difference was not observed between the sarcomas and fibroadenomas (p=0.44). [Work supported by NIH CA111289.]
Mapping the vibroacoustic behavior of harp soundboxes.
Authors: Daltrop Shira , Kotlicki Andrzej , Waltham Chris
Published: October 2013

Modern harp soundboxes typically consist of a thin soundboard made of an acoustic wood with a definite set of resonances, and a relatively heavy conical or polygonal back in which there are several holes. These holes exist to allow access to the string attachments but also have important acoustical properties. Harps more than 200 years old frequently have small holes in the soundboard itself, and none in the back. The quality of the sound radiation from a harp is determined in large measure by the vibrational behavior of the soundboard and the motion of air in the soundholes. Using an impact hammer, accelerometer and acoustic-velocity probe, we have mapped the velocity of a harp soundboard, and that of the air in the soundholes, in response to excitation at the string attachment points. The relationship between these motions is complex but also crucial in determining the quality of the instrument.
Seismic airgun sounds recorded in the North Atlantic.
Authors: Nieukirk Sharon L. , Mellinger David K. , Moore Sue E. , Klinck Karolin , Heimlich Sara L. , Klinck Holger
Published: October 2013

Between 1999 and 2008, a consortium of international investigators deployed autonomous hydrophones to monitor seismic activity along the Mid-Atlantic Ridge. Although this experiment was designed to monitor low-frequency sounds from earthquakes, other natural and man-made sounds were also recorded. The periodic impulses produced by airguns from exploration activities around the Atlantic basin were one of the dominant signals detected in this dataset. Sounds associated with seismic exploration, particularly sounds from airgun arrays, have garnered interest recently due to concerns regarding the potential impact on marine mammals. In a previous publication, we reported that in 1999–2001 airgun sounds were recorded year-round on all hydrophones, but airgun activity peaked in the summer months. For this study, we used an automatic algorithm to detect airgun sounds in the 2001–2008 portion of the dataset. Raw detections were then visually examined by an experienced analyst to verify the accuracy of the detections. When airgun impulses were simultaneously recorded on four or more hydrophones, the location of the seismic exploration vessel was estimated. Results from this dataset will be presented in light of current knowledge of marine mammal distribution and migration patterns in the Atlantic.
Assessment of bubble curtain attenuator techniques for underwater pile driving noise mitigation.
Authors: Slater Michael A.
Published: October 2013

Public concern for prudent management of marine resources due to anthropogenic activity is large and growing. In particular, the potential for causing negative impacts to marine species including salmonids and mammals is sufficient motivation to consider all reasonable mitigation strategies to minimize these effects. An impact pile driver can introduce extremely high sound pressure levels into the environment, and a bubble curtain attenuator is one means to reduce noise propagated from each driven pile by changing the impedance along the primary path of propagation. Available literature describing the observed effectiveness of reductions measured during in situ pile driving monitoring while using a bubble curtain range from completely ineffective to substantially effective. As a result, opposing views both seek acoustic evidence to support the need to use, or not use, bubble curtain attenuators during impact pile driving activities. This paper provides a description of the current state of knowledge on the use of bubble curtain attenuators, outlines on-going activities to address the issue, identifies limitations to the knowledge base, and suggests recommendations to close the information gap.
Acoustic characterization of whale watching boats in the Azores.
Authors: Oliveira Cláudia , Gonçalves João , Cruz Maria João , Silva Mónica A. , Prieto Rui , Lammers Marc , Santos Ricardo S.
Published: October 2013

The whale-watching activity has been growing in the Azores during the last 15 years. To contribute to the sustainability and management of the activity it is crucial to monitor its influence on cetacean populations. This work aimed to determine the sound produced by whale-watching boats, in terms of frequencies and sound pressure levels (SPLs). Different types of boats were recorded between May and Sept. 2007 around the islands of Faial, Pico, and S. Miguel. Recordings were made with a hydrophone from a drifting platform. The whale-watching boats carried out several tracks with different speeds and changed gear (forward/reverse). SPL values varied between 74 and 116 dB re 1 μPa (1/3 octave band level) for both outboard and inboard engines, without any obvious difference between the two. One inboard catamaran produced 106 dB re 1 μPa at 50 kHz (18 knots, 50 m distance), which is higher than all the other SPLs, at the same frequency. Forward/reverse maneuvers in inboard engines had lower frequencies but a longer duration than in outboard boats. Frequency range produced by the Azorean whale-watching boats is wide and the way boats are maneuvered is important to minimize their impact on cetaceans. [Work was supported by Direcção Regional do Turismo do Governo Regional dos Açores and Secretaria Regional do Ambiente e do Mar do Governo Regional dos Açores.]
Modeling acoustic response of permeability variation in deepwater wells using spectral method.
Authors: Karpfinger Florian , Gurevich Boris , Bakulin Andrey
Published: October 2013

Petroleum production in deepwater oil fields often hinges on the ability to safely complete and effectively draw down a small number of very challenging wells. The success of this operation requires regular completion monitoring, which is most effectively achieved using real-time surveillance tools. Real-time completion monitoring with acoustic waves (RTCM) has great potential for diagnosing problems in sand-screened deepwater completions. RTCM uses tube waves to detect permeability changes and passive noises to characterize perforation flow. Interaction of a single tube wave with permeable formations in open boreholes is well explained by Biot’s theory of poroelasticity. However, experimental studies in laboratory models of sand-screened completions reveal existence of two tube wave modes: fast and slow, supported by completion and sand screen, respectively. Development of quantitative monitoring methodology of acoustic surveillance requires better understanding on how signatures of fast and slow tube waves depend on completion properties. To this end, we simulate two tube dispersion and attenuation by examining the solutions of Biot’s equations of poroelasticity in cylindrical structures using a spectral method. The results show dependence of the velocity and attenuation of both tube waves on completion permeability. These modeling results are in a qualitative agreement with laboratory experiments.
Spectral method for modeling waves in cylindrical poroelastic structures.
Authors: Karpfinger Florian , Gurevich Boris , Bakulin Andrey , Valero Henri-Pierre
Published: October 2013

The modeling of propagating modes in poroelastic fluid-saturated cylindrical structures is important for the interpretation of acoustic and seismic measurements in hydrocarbon wells as well as laboratory measurements on core samples. In order to obtain the velocities of different modes the roots of the appropriate dispersion equation have to be found. This is a very difficult task especially when some layers are represented by poroelastic materials with frequency-dependent attenuation. A new technique is presented for modeling those modes, which adopts a spectral method to discretize the underlying partial differential equations using Chebyshev differentiation matrices. The corresponding system of linear equations can then be solved as a generalized eigenvalue problem. This means that, for a given frequency, the eigenvalues correspond to the slownesses of different modes. This approach is implemented for an arbitrary number of cylindrical fluid and solid layers as well as poroelastic layers. In addition to the dispersion, the attenuation curves are computed as well as radial profiles of displacements and stresses for various frequencies. The resulting approach can be used to model wave propagations in open and completed boreholes surrounded by permeable formations. This can pave the way to invert for formation and completion permeability from acoustic measurements.
Impedance tube measurements of gravel at frequencies between 25 and 200 Hertz.
Authors: White Michael J. , Swenson George W. , Oelze Michael L.
Published: October 2013

The sound absorption properties for a few materials have been examined for noise control, yet few materials are as durable and as cheap as gravel. We have measured the attenuation coefficient and wavelength in crushed limestone and pea gravel using an impedance tube. The tube is made of heavy steel, has 0.76-m inner diameter, height 7.3 m, and is fitted with 31 microphones flush-mounted on a line along the inside wall, using 0.2-m spacings. The tube can be filled with a variable depth (0–7 m) of test material, to be supported by either a perforated or solid rigid end plate. Over the frequencies 25–200 Hz, sound speed in 12-mm crushed limestone and 6-mm unsifted pea gravel increased from 160 to 200 m/s. Strongly graded 6-mm pea gravel was poorly dispersive, with sound speed averaging 210 m/s. Over the same frequency interval, the absorption coefficient increased from 0.4 to 1.1 Np/m in coarsely-graded pea gravel. The same positive trend, but successively lower attenuation, was found for crushed limestone and strongly-graded pea gravel. So far, the impedance has been more difficult to determine. Next, we plan to incorporate measurements of complex pressures in an attempt to improve the estimates.
Self-calibrating measurements of the density and velocity of sound from the reflection of ultrasound at two solid-liquid interfaces.
Authors: Greenwood Margaret S.
Published: October 2013

This report describes a method to measure the density of a liquid and velocity of sound by observing two reflections of ultrasound from a solid-liquid interface: one for perpendicular incidence of a longitudinal wave and the second for incidence of a shear wave at an angle of 45 deg. In previous research [J. Fluids Eng. 126, 189 (2004)], transducers were mounted on the outside of a stainless steel pipeline, 6 mm thick. Multiple reflections within the wall yielded the acoustic impedance. This method is self-calibrating because each echo is affected in the same way by any change in transducer voltage. The velocity of sound was obtained from the time-of-flight (TOF) across the pipeline. The current research replaces the TOF measurement by using a triangular stainless steel wedge (45, 90, 45 deg). A 1-MHz shear wave transducer is mounted on one short side of the wedge, with the longer side immersed in the liquid. Multiple reflections from the opposite side of the wedge are obtained. The two reflection coefficients can be used to solve for the density and velocity of sound. Greater precision can be obtained by using fused quartz instead of stainless steel.
The influence of masker fringe on sound localization in noise.
Authors: Simpson Brian D. , Gilkey Robert H. , Brungart Douglas S. , Iyer Nandini , Romigh Griffin D.
Published: October 2013

Several studies have shown that detection of a dichotic target signal in a concurrent diotic noise masker improves when the masker onset occurs prior to that of the target and/or the masker duration extends beyond the target offset (so-called masker fringe; McFadden, 1966; Trahiotis et al. 1972). It has been argued that this improved performance results from the fact that the masker fringe provides a baseline set of interaural parameters against which a change in parameters, associated with the signal onset or offset, can be detected. As the duration of the fringe increases, more time is available to estimate these baseline parameters, thus improving signal detectability. However, little is known about the relation between masker fringe and spatial hearing. In this study, the localization of a 250-ms click train signal presented in a broadband directional noise masker was measured as a function of the duration of the masker fringe and the signal-to-noise ratio. The results indicate that the presence of masker fringe improves localization performance relative to the case in which the masker and signal are pulsed on and off simultaneously. Moreover, the benefit of masker fringe increases with decreasing signal-to-noise ratio. [Work supported by a grant from AFOSR.]
The effect of flanking bands on sensitivity to interaural time differences.
Authors: Brown Christopher A. , Yost William A.
Published: October 2013

We are examining the potential for cochlear implant patients who retain some low-frequency residual hearing in both ears to benefit from interaural time differences (ITDs) to improve speech reception. Given the likelihood of asymmetrical loss in the low-frequency region, the relationship between spectral overlap and ITD sensitivity is of interest. We previously measured ITD sensitivity using narrow-band noise carriers, while varying the amount of spectral overlap between the ears. We found very good sensitivity when the bands completely overlapped, but for most listeners, sensitivity declined as the center frequency of one band was moved away from the other. When, for example, 2/3-octave bands were offset by 1/3 octave and presented to each ear, ITD sensitivity declined. This condition consists of three bands, a 1/3-octave center band that is spectrally similar across ears, and two 1/3-octave flanking bands, each of which is present in one or the other ear. Because the center band alone produces good ITD sensitivity, we hypothesized that moving the flankers away in frequency from the center band would result in improved sensitivity. However, the presence of the spectrally displaced bands led to poorer ITD sensitivity. [Work supported by grants from NIDCD.]
Gender differences in the ability to ignore distracters in frequency discrimination tasks.
Authors: Espinoza-Varas Blas , Jajoria Praveen
Published: October 2013

Whether there are gender differences in the ability to ignore distracting auditory information remains a matter of debate; such differences could be in basic, involuntary, novelty responses or in elaborate, voluntary, directed attention. To investigate this issue, frequency discrimination thresholds (FDTs) were measured in 20 males and 20 females (young, healthy adults with normal hearing). Targets tones (T) were presented in isolation or followed by a distracter tone (D) after a 90- or a 250-ms silent interval (ISI). Both tones were 1000 Hz, 70 dB SPL, and duration was 40 and 80 ms for T and D, respectively. Target frequency differences were specified by an adaptive rule targeting 71 percent-correct FDTs; irrelevant differences in D frequency were 40 or 45 Hz. On each subject, FDTs were measured for T in isolation or followed by D, with or without irrelevant differences; a total of 12 trial blocks per condition were completed. Across gender, the largest FDT disparity was observed in conditions with irrelevant differences in D frequency and 90-ms ISI; in the other conditions the gender effect was small or negligible. There appears to be a gender difference in the initial, involuntary, response to distracters.
Effect of narrowband noise maskers on increment detection.
Authors: Messersmith Jessica J , Patra Harisadhan , Jesteadt Walt
Published: October 2013

The ability to detect a brief increment in intensity in a longer duration stimulus is often used as a measure of the intensity resolution of the auditory system, but it is unclear how listeners perform the task. Early investigators suggested that detection of an increment in intensity was based on the overall energy within the critical band centered on the signal frequency. The use of signal energy falling outside of the critical band is often limited by introducing a noise masker. Recent findings indicate that envelope fluctuations in a masker can increase thresholds in increment detection, suggesting a decision process based on envelope modulation. A modulation-based decision device was evaluated by adding irregularity to the envelope of an increment detection task via noise maskers of varying bandwidth. Results indicate that thresholds for detection of an increment in the intensity of a pure tone increase with increasing bandwidth for an on-frequency noise masker, but are unchanged by an off-frequency noise masker. A model that includes a modulation filter bank analysis of envelope modulation can account for observed data, but a model based on discrimination of spectral patterns does equally well. [Work supported by R01 DC006648 and T32 DC000013.]
Modulation detection of sawtooth-wave modulated tones: Effect of temporal asymmetry.
Authors: Shen Yi , Lentz Jennifer
Published: October 2013

Large perceptual differences can be observed between ramped and damped sounds. In the present study, the effect of temporal asymmetry on amplitude modulation detection was studied with the use of two types of modulators: a ramped sawtooth wave, characterized by a gradual linear rise in amplitude followed by a sharp drop within each period, and the damped sawtooth wave which is the time reverse of the ramped wave. Results showed that a puretone carrier modulated by these two modulators led to differences in modulation detection thresholds with the damped modulation pattern being easier to detect than the ramped modulation pattern. The size of this effect was also dependent on the modulation rate. A model of auditory processing was proposed to account for the temporal asymmetry in modulation detection with the hypothesis that the asymmetric threshold originated at processing stages more central to the auditory nerve.
Model-based direction estimation of concurrent speakers in the horizontal plane.
Authors: Dietz Mathias , Ewert Stephan D. , Hohmann Volker
Published: October 2013

A computational auditory model for the direction estimation of concurrent speakers in the horizontal plane is presented. The auditory signal processing is motivated by mammalian physiology and human psychoacoustic data, extending the binaural model by Dietz et al. [Brain Res., 1220, 234–245 (2008)]. The model exploits a wide range of interaural parameters, namely, the interaural level difference, the interaural phase difference of the fine structure, and the interaural coherence. The parameters are determined at the output of auditory filters allowing for a simultaneous estimation of several sound source directions in a multidimensional internal representation. By focusing on time segments with high interaural coherence [Faller and Merimaa, J. Acoust. Soc. Am. 116, 3075–3089 (2004)] in the auditory bands, which likely stem from a localized sound source, the robustness of the direction estimation of the model was considerably improved: for two well-separated speakers in quiet, the estimation error is generally less than or equal to 10 deg. In noisy environments, the direction of a single speaker can be estimated for signal-to-noise ratios below 0 dB. Further improvements of the model by concurrent pitch estimation to reduce permutation errors between nearby speakers are investigated and discussed.
A comparison of modulation indices for describing amplitude-compressed speech.
Authors: Souza Pamela , Gallun Frederick , Hoover Eric
Published: October 2013

This presentation explores two approaches to characterizing changes to speech with amplitude-compression amplification. In the first, we considered changes to waveform morphology using the envelope difference index (EDI); [Fortune et al. (1994)] to quantify the effects on amplitude envelope in the time domain. In the second, the spectral correlation index (SCI); [Gallun & Souza (2008)] was used to compare signal envelopes in the frequency domain. In the SCI, similarity is represented by the correlation of the average modulation spectra at six octave-spaced amplitude modulation frequencies (1–32 Hz) in six octave-spaced carrier frequency regions (250–8000 Hz) for a pair of phonemes. Test stimuli were a set of 16 vowel-consonant-vowel (VCV) syllables spoken by four talkers. The VCVs were digitally processed to limit spectral information using a signal-correlated noise technique [Schroeder (1968)] then submitted to a compression amplification simulation in which parameters (compression ratio and release time) were selected to achieve a range of temporal alteration. Consonant identification scores for 10 normal-hearing listeners were obtained and related to the modulation indices. Although the SCI was more sensitive to changes in specific compression parameters, the EDI was more closely related to recognition. [Work supported by R01 DC0060014 and VA RR&D CDA-2 C4963W.]
Gradient measures of children’s speech production: Visual analog scale and equal appearing interval scale measures of fricative goodness.
Authors: Urberg-Carlson Kari , Munson Benjamin , Kaiser Eden
Published: October 2013

Cross-sectional and longitudinal studies of speech-sound development utilizing phonetic transcription often show an apparently discontinuous acquisition of speech sounds. Instrumental studies, in contrast, suggest that children acquire speech-sound contrasts gradually. An ideal perceptual-rating measure of children’s production should capture this gradient change in production, correlate well with acoustic data, and be fast and easy both to administer and to score. A previous experiment in our laboratory compared three methods of collecting continuous judgments of children’s consonant productions of /s/ and /∫/: Of the three, visual analog scaling (VAS) correlated best with acoustic parameters. However, as was administered in that experiment, VAS allowed only two-way comparisons between phonemes. To determine whether VAS could be used for multiple-way comparisons, two experiments were conducted. In the first, participants first made a forced choice between two phonemes, then used VAS to make a judgment of the goodness of the phoneme, from perfect to bad. A second experiment was conducted using a seven-point EAI scale in place of the VAS. The results will be correlated with acoustic data as in the previous experiment and will further our knowledge of optimal methods for measuring children’s speech production perceptually.
On the precision of noise-correlation interferometry.
Authors: Weaver Richard , Hadziioannou Celine , Larose Eric , Campillo Michel
Published: October 2013

Coda Wave Interferometry analyzes changes in diffuse waveforms when source and receiver are fixed. Changes are often due to changing acoustic wave speed, perhaps a change of temperature. Alternatively, changes can be studied in noise correlations. The advantage is in not having to wait for, or generate, a precisely identical source. But interpretation is problematic; changes in the correlation of noise fields due to an uncontrolled set of sources could be due to the sources, or to the environment. Recent studies of ambient seismic noise correlations have shown apparent stretches (potentially corresponding to wave speed slowing by parts in 10 000) over periods of weeks. Changes seen at La Reunion correlate with subsequent volcanic eruptions. Changes seen at Parkfield, California occur quickly after earthquakes and then relax back over many months. Potential for seismic monitoring motivates a study of the relative effects of source and medium changes on apparent stretching or compression. Here it is shown that long duration coda like character in a waveform permits a highly accurate estimate of stretch, an estimate that is relatively independent of changes in sources. The theory is supported by laboratory measurements and seismic data.
Maximizing mutual information in horizontal linear arrays.
Authors: Zhu Xiaoli , Buck John R.
Published: October 2013

Estimating the bearing of a sound source using a towed horizontal array is a common array processing problem. In a passive sonar system, it is common to null sources from the forward endfire direction to eliminate the noise of the towing vessel. This research designs linear nonuniform symmetric arrays of a fixed aperture for estimating the bearing of sound source. Specifically, the hydrophone spacings for a symmetric linear array are chosen to maximize the upper bound on mutual information between the true bearing and the bearing estimate in white noise. The arrays’ maximizing the mutual information while nulling forward endfire look significantly different from the uniform arrays commonly used in towed systems, and also differ from arrays designed to minimize spacing redundancy. Arrays maximizing mutual information are helpful when bearing estimation is considered as a quantization problem to assign the source to the correct partition. In this approach, increasing the mutual information should reduce the probability of error (Pe) in choosing the partition containing an unknown source. Simulation results demonstrate that the optimum arrays proposed here have much lower Pes than the uniform array. [Work funded by ONR code 321US.]
Three-dimensional modeling of acoustic propagation in the Florida Straits.
Authors: Saintval Wendy , Wylie Jennifer , DeFerrari Harry A.
Published: October 2013

A 3-D coupled broadband parabolic equation model is used to study shallow-water propagation for a direction of transmission parallel to a sloping inshore bottom bathymetry. Three sets of arrivals result: (1) direct paths—the typical 2-D model results; (2) curved inshore paths that make several bounces first up and then down the sloping bottom; and (3) micropaths that result from reflection off random facets of the bottom around the direct paths. Archival sound speed data from the Florida Straits at the site of a propagation experiment are used as input to investigate the observed anomalously low transmission loss for some of the long-range inshore paths. It is shown that both temporal and spatial focusing effects are at play to reduce transmission loss by as much as 15 dB for the inshore paths as compared with the corresponding direct paths having nearly the same mode characteristics. Also, the models help explain a peculiar observation for some of the longer inshore paths where the travel time actually decreases with increasing range of transmission.
Underwater acoustic measurements of Doppler-shifted Bragg scattering in the vertical plane from interaction with the ocean surface.
Authors: Lynch Stephen D. , D’Spain Gerald L.
Published: October 2013

High resolution beamformer output in the vertical plane for received fields from narrowband acoustic tones transmitted at 280, 370, 535, and 695 Hz shows evidence of Doppler-shifted Bragg scattering by the ocean surface waves. The sidebands in the beamformer output are offset in frequency by amounts corresponding to ocean surface wave frequencies, while deviations in vertical arrival angle agree with those predicted by the Bragg condition through first-order perturbation theory using measured directional surface wave spectra and measured acoustic mode wave numbers. The acoustic measurements were made by a horizontal hydrophone array on the ocean bottom in a shallow water waveguide under a variety of ocean surface conditions. [Work supported by ONR, Code 321(US).]
Source amplitude spectral information in matched-field localization.
Authors: Wilmut Michael J. , Dosso Stan E.
Published: October 2013

This paper examines a variety of approaches to make use of knowledge of the relative amplitude spectrum of an acoustic source (but no knowledge of the phase spectrum) in multifrequency matched-field processing for source localization. A common example of this procedure involves cases where the source amplitude spectrum can be considered flat over the frequency band of interest. The primary issue is how to combine the information of complex acoustic fields at multiple frequencies, given the unknown phase spectrum. Approaches examined include maximum-likelihood phase estimation, pair-wise processing, and phase rotation to zero the phase at a specific sensor or to zero the mean phase over the array. The performance of the various approaches (processors) is quantified in terms of the probability of localizing the source within an acceptable range-depth region, as computed via Monte Carlo sampling over a large number of random realizations of noise and of environmental parameters. Processor performance is compared as a function of signal-to-noise ratio, number of frequencies, number of sensors, and number of time samples (snapshots) included in the signal averaging.
Warping based lag-Doppler filtering applied to motion effect compensation in acoustical multipath propagation.
Authors: Josso Nicolas , Ioana Cornel , Mars Jérôme , Gervaise Cédric , Stephan Yann
Published: October 2013

The estimation of an impulse response of a propagation channel is necessary for a large number of underwater applications: underwater communication, sonar detection and localization, marine mammal monitoring, etc. Basically it informs us about the distortions of transmitted signal in underwater channels and enables geoacoustic inversion. The propagated signal is usually subject to additional and undesirable distortions due to the motion of the transmitter-channel-receiver configuration. This paper points out the effects of the motion while estimating the IR by matching filtering between the transmitted and the received signals. A methodology to compare the IR estimation in motionless and motion contexts is presented. Based on this comparison, a warping-based lag-Doppler filtering method in the wideband ambiguity plane for motion effect compensation is proposed. It aims at reducing the distortions due to the motion phenomena and accurately estimating the IR of the channel. The proposed methodology is applied to real data sets issued from BASE’07 campaign (NURC, SHOM, and FWG, South of Sicilia, 2007). Motion compensated estimations of IRs are computed from sources transmitting broadband linear frequency modulations moving up to 12 knots in the shallow water environment of the Malta plateau.
Model and measurement of high-frequency bottom backscattering intensity envelope.
Authors: Wu Jinrong , Lu Licheng , Guo Shengming , Ma Li
Published: October 2013

High-frequency bottom scattering, generally, can be attributed to bottom interface roughness and volume inhomogeneities. The full grazing angle (0–90 deg) intensity envelope model of high-frequency bottom backscattering generated by these two kinds of mechanism was presented. Small-slope approximation method was used to explain bottom roughness backscattering. Bottom volume scattering coefficient was used to calculate bottom volume scattering assuming the volume scattering is homogeneous. The model incorporates the shape of transmitted pulse, directionality of transducer, scattering area, bottom characteristic, and so on. Tank experiment result shows the bottom roughness is the key factor to fine sand bottom backscattering. This backscattering intensity envelope model is useful for the application of bottom backscattering signal, such as sediment classification and geoacoustic inversion. [Work supported by the NSFC.]