bluuebunny/crossref_metadata_2025 huggingface dataset:
A micro-machined hydrophone using the piezoelectric-gate-of-field-effect-transistor for low frequency sounds
Authors: Sung Min , Shin Kumjae , Joh Cheeyoung , Moon Wonkyu
Published: October 2014

The micro-sized piezoelectric body for the miniaturized hydrophone is known to have the limits in low frequencies due to its high impedance and low sensitivity. In this study, a new transduction mechanism named as PiGoFET (piezoelectric gate of field effect transistor) is devised so that its application for the miniaturized hydrophone could overcome the limits of the micro-sized piezoelectric body. The PiGoFET transduction can be realized by combining a field effect transistor and a small piezoelectric body on its gate. A micro-machined silicon membrane of 2 mm diameter was connected to the small piezoelectric body so that acoustic pressure can apply appropriate forces on the body on the FET gate. The electric field from the deformed piezoelectric body modulates the channel current of FET directly, thus the transduction makes the sound pressure transferred to the source–drain current effectively at very low frequencies with micro-sized piezoelectric body. Under the described concept, a hydrophone was fabricated by micro-machining and calibrated using the comparison method in low frequencies to investigate its performance. [Research funded by MRCnD.]
Characterizing the nonlinear interaction of S (shear) and P (longitudinal) waves in reservoir rocks
Authors: Szabo Thomas L. , Gallot Thomas , Malcolm Alison , Brown Stephen , Burns Dan , Fehler Michael
Published: October 2014

The nonlinear elastic response of rocks is known to be caused by internal microstructure, particularly cracks and fluids. In order to quantify this nonlinearity, this paper presents a method for characterizing the interaction of two nonresonant traveling waves: a low-amplitude P-wave probe and a high-amplitude lower frequency S-wave pump with their particle motions aligned. We measure changes in the arrival time of the P-wave probe as it passes through the perturbation created by a traveling S-wave pump in a sample of room-dry Berea sandstone (15 × 15 × 3 cm). The velocity measurements are made at times too short for the shear wave to reflect back from the bottom of the sample and interfere with the measurement. The S-wave pump induces strains of 0.3—2.2 × 10−6, and we observe changes in the P-wave probe arrival time of up to 100 ns, corresponding to a change in elastic properties of 0.2%. By changing the relative time delay between the probe and pump signals, we record the measured changes in travel time of the P-wave probe to recover the nonlinear parameters β~ −102 and δ ~−109 at room-temperature. This work significantly broadens the applicability of dynamic acousto-elastic testing by utilizing both S and P traveling waves.
A case study of multipole acoustic logging in heavy oil sand reservoirs
Authors: Liu Peng , Qiao Wenxiao , Che Xiaohua , Wang Ruijia , Ju Xiaodong , Lu Junqiang
Published: October 2014

The multipole acoustic logging tool (MPAL) was tested in the heavy oil sand reservoirs of Canada. Compared with near shales, the P-wave slowness of heavy oil sands does not change obviously, with the value of about 125μs/ft; the dipole shear slowness decreases significantly to 275μs/ft. The heavy oil sands have a Vp/Vs value of less than 2.4. The slowness and amplitude of dipole shear wave are good lithology discriminators that have great differences between heavy oil sands and shales. The heavy oil sand reservoirs are anisotropic. The crossover phenomenon in the fast and slow dipole shear wave dispersion curves indicates that the anisotropy is induced by unbalanced horizontal stress in the region.
Faraday waves on a two-dimensional periodic substrate
Authors: Maki C. T. , Rodriguez Peter , Dele-Oni Purity , Fu Pei-Chuan , Holt R. Glynn
Published: October 2014

A vertically oscillating body of liquid will exhibit Faraday waves when forced above a threshold interface acceleration amplitude. The patterns and their wavelengths at driving frequencies of order 100 Hz are well known in the literature. However, wave interactions influenced by periodic structures on a driving substrate are less well-studied. We report results of a Faraday experiment with a specific periodically structured substrate in the strong coupling regime where the liquid depth is of the order of the structure height. We observe patterns and pattern wavelengths versus driving frequency over the range of 50–350 Hz. These observations may be of interest in situations where Faraday waves appear or are applied.
Auditory processing disorder: Clinical and international perspective
Authors: Moore David R.
Published: October 2014

APD may be considered a developmental, hearing or neurological disorder, depending on etiology, but in all cases, it is a listening difficulty without an abnormality of pure tone sensitivity. It has been variously defined as a disorder of the central auditory system associated with impaired spatial hearing, auditory discrimination, temporal processing, and performance with competing or degraded sounds. Clinical testing typically examines perception, intelligibility and ordering of both speech and non-speech sounds. While deficits in higher-order cognitive, communicative, and language functions are excluded in some definitions, recent consensus accepts that these functions may be inseparable from active listening. Some believe that APD in children is predominantly or exclusively cognitive in origin, while others insist that true APD has its origins within the auditory brainstem. However, children or their carers presenting at clinics typically complain of difficulty hearing speech in noise, remembering or understanding instructions, and attending to sounds. APD usually occurs alongside other developmental disorders (e.g., language impairment) and may be indistinguishable from them. Consequently, clinicians are uncertain how to diagnose or manage APD; both test procedures and interventions vary widely, even within a single clinic. Effective remediation primarily consists of improving the listening environment and providing communication devices.
Quantifying supra-threshold sensory deficits in listeners with normal hearing thresholds
Authors: Shinn-Cunningham Barbara , Bharadwaj Hari , Choi Inyong , Goldberg Hannah , Masud Salwa , Mehraei Golbarg
Published: October 2014

There is growing suspicion that some listeners with normal-hearing thresholds may be suffering from a specific form of sensory deficit—a loss of afferent auditory nerve fibers. We believe such deficits manifest behaviorally in conditions where perception depends upon precise spectro-temporal coding of supra-threshold sound. In our lab, we find striking inter-subject differences in perceptual ability even among listeners with normal hearing thresholds who have no complaints of hearing difficulty and have never sought clinical intervention. Among such ordinary listeners, those who perform relatively poorly on selective attention tasks (requiring the listener to focus on one sound stream presented amidst competing sound streams) also exhibit relatively weak temporal coding in subcortical responses and have poor thresholds for detecting fine temporal cues in supra-threshold sound. Here, we review the evidence for supra-threshold hearing deficits and describe measures that reveal this sensory loss. Given our findings in ordinary adult listeners, it stands to reason that at least a portion of the listeners who are diagnosed with central auditory processing dysfunction may suffer from similar sensory deficits, explaining why they have trouble communicating in many everyday social settings.
Do subglottal resonances lead to quantal effects resulting in the features [back] and [low]?: A review
Authors: Hanson Helen , Shattuck-Hufnagel Stefanie
Published: October 2014

A question of general interest is why languages have the sound categories that they do. K. N. Stevens proposed the Quantal Theory of phonological contrasts, suggesting that regions of discontinuity in the articulatory-acoustic mapping serve as category boundaries. H. M. Hanson and K. N. Stevens [Proc. ICPhS, 182–185, 1995] modeled the interaction of subglottal resonances with the vocal-tract filter, showing that when a changing supraglottal formant strays into the territory of a stationary tracheal formant, a discontinuity in supraglottal formant frequency and attenuation of the formant peak occurs. They suggested that vowel space and quality could thus be affected. K. N. Stevens [Acoustic Phonetics, MIT Press, 1998] went further, musing that because the first and second subglottal resonances lead to instabilities in supraglottal formant frequency and amplitude, vowel systems would benefit by avoiding vowels with formants at these frequencies. Avoiding the first subglottal resonance would naturally lead to the division of vowels into those with a low vs. non-low tongue body; avoiding the second would lead to the division of vowels into those having a back vs. front tongue body. We will review subsequent research that offers substantial support for this hypothesis, justifying inclusion of the effects of subglottal resonances in phonological models.
A comparison of acoustic and perceptual changes in children’s productions of American English /r/
Authors: Hamilton Sarah , Keck Casey , Boyce Suzanne
Published: October 2014

Speech-language pathologists rely primarily on their perceptual judgments when evaluating whether children have made progress in speech sound therapy. Speech sound perception in normal listeners has been characterized as largely categorical, such that slight articulatory changes may go unnoticed unless they reach a specific acoustic signature assigned to a different category. While perception may be categorical, acoustic phenomena are largely measured in continuous units, meaning that there is a potential mismatch between the two methods of recording change. Clinicians, using perceptual categorization, commonly report that some children make no progress in therapy, yet acoustically, the children’s productions may be shifting toward acceptable acoustic characteristics. Using subtle changes in the acoustic signal during therapy could potentially prevent these clients from being discharged due to a perceived lack of progress. This poster evaluates acoustic changes compared to perceptual changes in children’s productions of the American English phoneme /r/ after receiving speech therapy using ultrasound supplemented with telepractice home practice. Preliminary data indicate that there are significant differences between participants’ acoustic values of /r/ and perceptual ratings by clinicians.
Moving targets and unsteady states: “Shifting” productions of sibilant fricatives by young children
Authors: Reidy Patrick
Published: October 2014

The English voiceless sibilant /s/--/ʃ/ contrast is one that many children do not acquire until their adolescent years. This protracted acquisition may be due to the high level of articulatory control that is necessary to the successful production of an adult-like sibilant, which involves the coordination of lingual, mandibular, and pulmonic gestures. Poor coordination among these gestures can result in the acoustic properties of the noise source or the vocal tract filter changing throughout the timecourse of the frication, to the extent that the phonetic percept of the frication noise changes across its duration. The present study examined such “shifting” productions of sibilant fricatives by native English-acquiring two- through five-year-old children, which were identified from the Paidologos corpus as those productions where the interval of frication was transcribed phonetically as a sequence of fricative sounds. There were two types of shift in frication quality: (1) a gradual change in the resonant frequencies in the spectrogram, suggesting a repositioning of the oral constriction; and (2) an abrupt change in the level of the frication, suggesting a switch in the noise source. Work is underway to develop measures that differentiate these two types of shift, and that suggest their underlying articulatory causes.
Acoustic-phonetic characteristics of older children’s spontaneous speech in interactions in conversational and clear speaking styles
Authors: Hazan Valerie , Pettinato Michèle , Tuomainen Outi , Granlund Sonia
Published: October 2014

This study investigated (a) the acoustic-phonetic characteristics of spontaneous speech produced by talkers aged 9–14 years in an interactive (diapix) task with an interlocutor of the same age and gender (NB condition) and (b) the adaptations these talkers made to clarify their speech when speech intelligibility was artificially degraded for their interlocutor (VOC condition). Recordings were made for 96 child talkers (50 F, 46 M); the adult reference values came from the LUCID corpus recorded under the same conditions [Baker and Hazan, J. Acoustic. Soc. Am. 130, 2139–2152 (2011)]. Articulation rate, pause frequency, fundamental frequency, vowel area, and mean intensity (1–3 kHz range) were analyzed to establish whether they had reached adult-like values and whether young talkers showed similar clear speech strategies as adults in difficult communicative situations. In the NB condition, children (including the 13–14 year group) differed from adults in terms of their articulation rate, vowel area, median F0, and intensity. Child talkers made adaptations to their speech in the VOC condition, but adults and children differed in their use of F0 range, vowel hyperarticulation, and pause frequency as clear speech strategies. This suggests that further developments in speech production take place during later adolescence. [Work supported by ESRC.]
Acoustic characteristics of infant-directed speech to normal-hearing and hearing-impaired twins with hearing aids and cochlear implants: A case study
Authors: Kondaurova Maria V. , Bergeson-Dana Tonya R. , Wright Neil A.
Published: October 2014

The study examined acoustic characteristics of maternal speech to normal-hearing (NH) and hearing-impaired (HI) twins who received hearing aids (HAs) or a unilateral cochlear implant (CI). A mother of female-male NH twins (NH-NH; age 15.8 months), a mother of two male twins, one NH and another HI with HAs (NH-HA; age 11.8 months) and a mother of a NH female twin and a HI male twin with a CI (NH-CI; age 14.8 months) were recorded playing with their infants during three sessions across a 12-month period. We measured pitch characteristics (normalized F0 mean, F0 range, and F0 SD), utterance and pause duration, syllable number, and speaking rate. ANOVAs demonstrated that speech to NH-NH twins was characterized by lower, more variable pitch with greater pitch range as compared to speech to NH-HA and NH-CI pairs. Mothers produced more syllables, had faster speaking rate and longer utterance duration in speech to NH-NH than the other pairs. The results suggest that the pediatric hearing loss in one sibling affects maternal speech properties to both NH and HI infants in the same pair. Future research will investigate vowel space and lexical properties of IDS to three twin pairs as well as their language outcome measures.
Audiovisual speech integration development at varying levels of perceptual processing
Authors: Lalonde Kaylah , Frush Holt Rachael
Published: October 2014

There are multiple mechanisms of audiovisual (AV) speech integration with independent maturational time courses. This study investigated development of both basic perceptual and speech-specific mechanisms of AV speech integration by examining AV speech integration development across three levels of perceptual processing. Twenty-two adults and 24 6- to 8-year-old children completed three auditory-only and AV yes/no tasks varying only in the level of perceptual processing required to complete them: detection, discrimination, and recognition. Both groups demonstrated benefits from matched AV speech and interference from mismatched AV speech relative to auditory-only conditions. Adults, but not children, demonstrated greater integration effects at higher levels of perceptual processing (i.e., recognition). Adults seem to rely on both general perceptual mechanisms of speech integration that apply to all levels of perceptual processing and speech-specific mechanisms of integration that apply when making phonetic decisions and/or accessing the lexicon; 6- to 8-year-old children seem to rely only on general perceptual mechanisms of AV speech integration. The general perceptual mechanism allows children to attain the same degree of AV benefit to detection and discrimination as adults, but the lack of a speech-specific mechanism in children might explain why they attain less AV recognition benefit than adults.
Optimal smoothing splines improve efficiency of entropy imaging for detection of therapeutic benefit in muscular dystrophy
Authors: Hughes Michael , McCarthy John , Marsh Jon , Wickline Samuel
Published: October 2014

We have reported previously on sensitivity comparisons of signal energy and several entropies to changes in skeletal muscle architecture in experimental muscular dystrophy before and after pharmacological therapeutic intervention [M. S. Hughes, IEEE Trans. UFFC. 54, 2291–2299 (2007)]. The study was based on a moving window analysis of simple cubic splines that were fit to the backscattered ultrasound and required that the radio frequency ultrasound (RF) be highly oversampled. The current study employs optimal smoothing splines instead to determine the effect of analyzing the same data with increasing levels of decimation. The RF data were obtained from selected skeletal muscles of muscular dystrophy mice (mdx: dystrophin -/-) that were randomly blocked into two groups: 4 receiving steroid treatment over 2 weeks, and 4 untreated positive controls. Ultrasonic imaging was performed on day 15. All mice were anesthetized then each forelimb was imaged in transverse cross sections using a Vevo-660 with a single-element 40 MHz wobbler-transducer (model RMV-704, Visualsonics). The result of each scan was a three dimensional data set 384 × 8192 × # frames in size. We find the equivalent sensitivity of this new approach for detecting treatment benefits as before (p<0.03), but now at a decimated sampling rate slightly below the Nyquist frequency. This implies that optimal smoothing splines are useful for analysis of data acquired from point of care imaging devices where hardware cost and power consumption must be minimized.
Determination of Room Impulse Response for synthetic data acquisition and ASR testing
Authors: Moquin Philippe , Venalainen Kevin , Florêncio Dinei A.
Published: October 2014

Automatic Speech Recognition (ASR) works best when the speech signal best matches the ones used for training. Training, however, may require thousands of hours of speech, and it is impractical to directly acquire them in a realistic scenario. Some improvement can be obtained by incorporating typical building acoustics measurement parameters such as RT, Cx, LF, etc., with limited gain. Instead, we estimate Room Impulse Responses (RIRs), and convolve speech and noise signals with the estimated RIRs. This produces realistic signals, which can then be processed by the audio pipeline, and used for ASR training. In our research, we use rooms with variable acoustics and repeatable source-receiver positions. The receivers are microphone arrays making the relative phase and magnitude critical. A standard mouth simulator for voice signals at various positions in the room is under robot control. A limited corpus of speech data as well as noise sources is recorded and the RIR at these 27 positions is determined using a variety of methods (chirp, MLS, impulse, and noise). The convolved RIR with the “clean speech” is compared to the actual measurements. Test methods used, differences from the measurements, and the difficulty of determining the unique RIR will be presented.
Quantifying the depth profile of time reversal focusing in elastic media
Authors: Anderson Brian E. , Remillieux Marcel C. , Ulrich Timothy J. , Le Bas Pierre-Yves
Published: October 2014

A focus of elastic energy on the surface of a solid sample can be useful to nondestructively evaluate whether the surface or the near-surficial region is damaged. Time reversal techniques allow one to focus energy in this manner. In order to quantify the degree to which a time reversal focus can probe near-surficial features, the depth profile of a time reversal focus must be quantified. This presentation will discuss numerical modeling and experimental results used to quantify the depth profile. [This work was supported by the U.S. Dept. of Energy, Fuel Cycle R&D, Used Fuel Disposition (Storage) Campaign.]
Focusing the acoustic signal of a maneuvering rotorcraft
Authors: Goldman Geoffrey H.
Published: October 2014

An algorithm was developed and tested to blindly focus the acoustic spectra of a rotorcraft that was blurred by time-varying Doppler shifts and other effects such atmospheric distortion. First, the fundamental frequency generated by the main rotor blades of a rotorcraft was tracked using a fix-lag smoother. Then, the frequency estimates were used to resample the data in time using interpolation. Next, the motion compensated data were further focused using a technique based upon the phase gradient autofocus algorithm. The performance of the focusing algorithm was evaluated by analyzing the increase in the amplitude of the harmonics. For most of the data, the algorithm focused the harmonics between approximately 10–90 Hz to within 1–2 dB of an estimated upper bound obtained from conservation of energy and estimates of the Doppler shift. In addition, the algorithm was able to separate two closely spaced frequencies in the spectra of the rotorcraft. The algorithm developed can be used to preprocess data for classification, nulling, and tracking algorithms.
Representing the structure of underwater acoustic communication data using probabilistic graphical models
Authors: Yellepeddi Atulya , Preisig James C.
Published: October 2014

Exploiting the structure in the output of the underwater acoustic communication channel in order to improve the performance of the communication system is a problem that has received much recent interest. Methods such as physical constraints and sparsity have been used to represent such structure in the past. In this work, we consider representing the structure of the received signal using probabilistic graphical models (more specifically Markov random fields), which capture the conditional dependencies amongst a collection of random variables. In the frequency domain, the inverse covariance matrix of the received signal is shown to have a sparse structure. Under the assumption that the signal may be modeled as a multivariate Gaussian random variable, this corresponds to a Markov random field. It is argued that the underlying cause of the structure is the cyclostationary nature of the signal. In practice, the received signal is not exactly cyclostationary, but data from the SPACE08 acoustic communication experiment is used to demonstrate that field data exhibits exploitable structure. Finally, techniques to exploit graphical model structure to improve the performance of wireless underwater acoustic communication are briefly considered.
SONAR Equation perspective on TREX13 measurements
Authors: Tang Dajun , Hefner Brian T.
Published: October 2014

Modeling shallow water reverberation is a problem that can be approximated as two-way propagation (including multiple forward scatter) and a single backward scatter. This can be effectively expressed in terms of the SONAR equation: RL = SL-2 x TL + SS, where RL is reverberation level, SL is the source level, TL is the one way transmission loss, and SS is the integrated scattering strength. In order to understand the reverberation problem at the basic research level, both propagation and scattering physics need to be properly addressed. A major goal of TREX13 (Target and Reverberation EXperiment 2013) is to quantitatively investigate reverberation with sufficient environmental measurement to support full modeling of reverberation data. Along a particular reverberation track at the TREX13 site, TL and direct-path backscatter were separately measured. Environmental data were extensively collected along this track. This talk will bring together all the components of the SONAR equation measured separately at the TREX13 site to provide an assessment of the reverberation process along with environmental factors impacting each of the components.
Environmental measurements collected during TREX13 to support acoustic modeling
Authors: Hefner Brian T. , Tang Dajun
Published: October 2014

The major goal of TREX13 (Target and Reverberation EXperiment 2013) was to quantitatively investigate reverberation with sufficient environmental measurements to support full modeling of reverberation data. The collection of environmental data to support reverberation modeling is usually limited by the large ranges (10s of km) involved, the temporal and spatial variability of the environment and the time variation of towed source/receiver locations within this environment. In order to overcome these difficulties, TREX13 was carried out in a 20 m deep shelf environment using horizontal line arrays mounted on the seafloor. The water depth and well controlled array geometry allowed environmental characterization to be focused on the main beam of the array, i.e., along a track roughly 5 km long and 500 m wide. This talk presents an overview of the efforts made to characterize the sea surface, water column, seafloor, and subbottom along this track to support the modeling of acoustic data collected over the course of the experiment. [Work supported by ONR Ocean Acoustics.]
Modeling reverberation in a complex environment with the finite element method
Authors: Isakson Marcia J. , Chotiros Nicholas P.
Published: October 2014

Acoustic finite element models solve the Helmholtz equation exactly and are customizable to the scale of the discretization of the environment. This makes them an ideal candidate for reverberation studies in complex environments. In this study, reverberation is calculated for a realistic shallow water waveguide. The environmental parameters are taken from the extensive characterization completed for the Target and Reverberation Experiment (TREX) conducted off the coast of the Florida panhandle in 2013. Measured sound speed profiles, sea surface roughness, bathymetry, and measured ocean bottom roughness are included in the model. Measurements of the normal incidence bottom loss are used as a proxy for range dependent sediment density. Results are compared with a closed form solution for reverberation. [Work sponsored by ONR, Ocean Acoustics.]
Normal incidence reflection measurements (TREX13): Inferences for lateral heterogeneity over a range of scales
Authors: Holland Charles W. , Smith Chad , Hines Paul
Published: October 2014

Normal incidence seabed reflection data suffer from a variety of ambiguities that make quantitative interpretation difficult. The reflection coefficient has an inseparable ambiguity between bulk density and compressional sound speed. Even more serious, reflection data are a function of other sediment characteristics including interface roughness, volume heterogeneities, and local bathymetry. Seafloor interface curvature is especially important and can lead to focusing/defocusing of the reflected field. An attempt is made with ancillary data including bathymetry, 400 kHz backscatter, and wide angle seabed reflection data to separate some of the mechanisms. Resulting analysis of 1–12 kHz reflection data suggest: (1) strong lateral sediment heterogeneity exists on scales of 10–100 m; (2) there are distinct geoacoustic regimes on the lee and stoss side of the ridge crest, and also between crest and the swale, and (3) the ridge crest geoacoustic properties are similar across distances of 6 km along two perpendicular transects (1 correlation). [Research supported by ONR Ocean Acoustics.]
Acoustic measurements on mid-shelf sediments with cobble: Implications for reverberation
Authors: Holland Charles W. , Steininger Gavin , Dettmer Jan , Dosso Stan , Lowrie Allen
Published: October 2014

The vast majority of sediment acoustics research has focused on rather homogeneous sandy sediments. Measurements for sediments containing cobbles (grain size greater than 6 cm) are rare. Here, measurements are presented for mid-shelf sediments containing pebbles/cobbles mixed with other grain sizes spanning 7 orders of magnitude, including silty clay, sand, and shell hash. The 2 kHz sediment sound speed in two distinct layers with cobble is 1531±5 m/s and 1800±20 m/s at the 95% credibility interval. The dispersion over the 400–2000 Hz band was relatively weak, 2 and 7 m/s respectively. The objective is to (1) present results for a sediment type for which little is known, (2) motivate development of theoretical wave propagation models for wide grain size distributions, and (3) speculate on the possibility of cobble as a scattering mechanism for mid shelf reverberation. The presence of cobbles from 1 to 3 m (possibly extending to 6 m) sub-bottom suggest they are the dominant scattering mechanism at this site. Though sediments with cobbles might be considered unusual, especially on the mid-shelf, they may be more common than the paucity of measurements would suggest since typical direct sampling techniques (e.g., cores and grab samples) have fundamental sampling limitations. [Research supported by ONR Ocean Acoustics.]
Auditory illusions of supernatural spirits: Archaeological evidence and experimental results
Authors: Waller Steven J. , Kolar Miriam A.
Published: October 2014

Sound reflection, reverberation, ricochets, and interference patterns were perceived in the past as eerie sounds attributable to invisible echo spirits, thunder gods, ghosts, and sound-absorbing bodies. These beliefs in the supernatural were recorded in ancient myths, and expressed in tangible archaeological evidence including canyon petroglyphs, cave paintings, and megalithic stone circles including Stonehenge. Disembodied voices echoing throughout canyons gave the impression of echo spirits calling out from the rocks. Thunderous reverberation filling deep caves gave the impression of the same thundering stampedes of invisible hoofed animals that were believed to accompany thunder gods in stormy skies. If you did not know about sound wave reflection, would the inexplicable noise of a ricochet in a large room have given you the impression of a ghost moaning “BOOoo” over your shoulder? Mysterious silent zones in an open field gave the impression of a ring of large phantom objects blocking pipers' music. Complex behaviors of sound waves such as reflection and interference (which scientists today dismiss as acoustical artifacts) can experimentally give rise to psychoacoustic misperceptions in which such unseen sonic phenomena are attributed to the supernatural. See https://sites.google.com/site/rockartacoustics/ for further details.
Pututus, resonance and beats: Acoustic wave interference effects at Ancient Chavín de Huántar, Perú
Authors: Kolar Miriam A.
Published: October 2014

Acoustic wave interference produces audible effects observed and measured in archaeoacoustic research at the 3,000-year-old Andean Formative site at Chavín de Huántar, Perú. The ceremonial center’s highly-coupled network of labyrinthine interior spaces is riddled with resonances excited by the lower-frequency range of site-excavated conch shell horns. These pututus, when played together in near-unison tones, produce a distinct “beat” effect heard as the result of the amplitude variation that characterizes this linear interaction. Despite the straightforward acoustic explanation for this architecturally enhanced instrumental sound effect, the performative act reveals an intriguing perceptual complication. While playing pututus inside Chavín’s substantially intact stone-and-earthen-mortar buildings, pututu performers have reported an experience of having their instruments’ tones “guided” or “pulled” into tune with the dominant spatial resonances of particular locations. In an ancient ritual context, the recognition and understanding of such a sensory component would relate to a particular worldview beyond the reach of present-day investigators. Despite our temporal distance, an examination of the intertwined acoustic phenomena operative to this architectural–instrumental–experiential puzzle enriches the interdisciplinary research perspective, and substantiates perceptual claims.
Removing the mask in multitrack music mixing
Authors: Case Alexander U.
Published: October 2014

The sound recording heard via stereo loudspeakers and headphones is made up of many dozens—sometimes more than 100—discrete tracks of musical elements. Multiple individual performances across a variety of instruments are fused into the final, two-channel recording—left and right—that is released to consumers. Achieving sonic success in this many-into-two challenge requires strategic, creative release from masking. Part of the artistry of multitrack mixing includes finding innovative signal processing approaches that enable the full arrangement and the associated interaction among the multitrack components of the music to be heard and enjoyed. Masking among tracks clutters and obscures the music. But audio engineers are not afraid. They want you hear what’s behind the mask. Hear how. Happy Halloween.
Segregation of ambiguous pulse-echo streams and suppression of clutter masking in FM bat sonar by anticorrelation signal processing
Authors: Simmons James A.
Published: October 2014

Big brown bats often fly in conditions where the density and spatial extent of clutter requires a high rate of pulse emissions. Echoes from one broadcast still are arriving when the next broadcast is sent out, creating ambiguity about matching echoes to corresponding broadcasts. Biosonar sounds are widely beamed and impinge on the entire surrounding scene. Numerous clutter echoes typically are received from different directions at similar times. The multitude of overlapping echoes and the occurrence of pulse-to-echo ambiguity compromises the bat’s ability to peer into the upcoming path and determine whether it is free of collision hazards. Bats have to associate echoes with their corresponding broadcasts to prevent ambiguity, and off-side clutter echoes have to be segregated from on-axis echoes that inform the bat about its immediate forward path. In general, auditory streaming to resolve elements of an auditory scene depends on differences in pitch and temporal pattern. Bats use a combination of temporal and spectral pitch to assign echoes to “target” and “clutter” categories within the scene, which prevents clutter masking, and they associate incoming echoes with the corresponding broadcast by treating the mismatch of echoes with the wrong broadcast as a type of clutter. [Supported by ONR.]
Challenges for second-language learners in difficult acoustic environments
Authors: Rogers Catherine L.
Published: October 2014

Most anyone who has lived in a foreign country for any length of time knows that even everyday tasks can become tiring and frustrating when one must accomplish them while navigating a seemingly endless maze of unfamiliar social customs, vocabulary and speech that seem far removed from one’s language laboratory experience. Add to these challenges noise, reverberation, and/or cognitive demand (e.g., learning caculus, responding to multiple customer, and co-worker demands) and even experienced learners may begin to question their proficiency. This presentation will provide an overview of the speech perception and production challenges faced by second-language learners in difficult acoustic environments that we may encounter every day, such as in large lecture halls, retail or customer service, to name a few. Past and current research investigating the effects of various environmental challenges on both relatively early and later learners of a second language will be considered, as well as strategies that may mitigate challenges for both speakers and listeners in some of these conditions.
Measurement and prediction of speech intelligibility in noise and reverberation for different sentence materials, speakers, and languages
Authors: Warzybok Anna , Hochmuth Sabine , Rennies Jan , Brand Thomas , Kollmeier Birger
Published: October 2014

The present study investigates the role of the speech material type, speaker, and language for speech intelligibility in noise and reverberation. The experimental data are compared to predictions of the speech transmission index. First, the effect of noise only, reverberation only, and the combination of noise and reverberation was systematically investigated for two types of sentence tests. The hypothesis to be tested was that speech intelligibility is more affected by reverberation when using an open-set speech material consisting of everyday sentences than when using a closed-set test with syntactically fixed and semantically unpredictable sentences. In order to distinguish between the effect of speaker and language on speech intelligibility in noise and reverberation, the closed-set speech material was recorded using bilingual speakers of German-Spanish and German-Russian. The experimental data confirmed that the effect of reverberation was stronger for an open-set test than for a closed-set test. However, this cannot be predicted by the speech transmission index. Furthermore, the inter-language differences in speech reception thresholds were on average up to 5 dB, whereas inter-talker differences were of about 3 dB. The Spanish language suffered more under reverberation than German and Russian, what again challenged the predictions of the speech transmission index.
Speech clarity in lively theatres
Authors: Miller Gregory A. , Giegold Carl
Published: October 2014

By their very nature, theatres must be “lively” acoustic spaces. The audience must hear one another, so laughter and applause can ripple around the room, and they must have the aural sensation of being in a large space heightens the excitement of being at a live performance. Similarly, the theatre must reflect sound back to the actors in a way that helps them to gauge how well their voices are filling the room, and to gauge audience response throughout the performance. And yet this liveliness runs counter to much of conventional wisdom regarding the acoustic conditions to support speech clarity. This paper will describe ways in which the acoustic response of a room can be built up to support both speech clarity and liveliness, with a particular emphasis on theatre spaces in which the actors are placed in the same volume as the audience (thrust and surround stages).
Speech communication in noise to valid the virtual sound capturing system
Authors: Jang Hyung Suk , Oh Seongmin , Jeon Jin Yong
Published: October 2014

The microphone systems were designed to capture the real sound field for the creation of the remote virtual coexistence space: omnidirectional microphone, binaural dummy head, linear array microphones, and spherical microphone. The captured signals were applied to synthesize into the binaural signal. These binaural cues were generated using head-related transfer function (HRTF) through headphone. For the validation, the sentence recognition tests were carried out to quantify the ability of speech perception with the sentence lists for normal listeners. In addition, the readability and the naturalness were used to assess the quality of the synthesized sounds. The different noise environments were applied with different signal to noise ratio and an efficient sound capturing system was suggested by the comparing the results of the sentence recognition tests.
Estimating singing fin whale population density using frequency band energy
Authors: Mellinger David K. , Küsel Elizabeth T. , Harris Danielle , Thomas Len , Matias Luis
Published: October 2014

Fin whale (Balaenoptera physalus) song occurs in a narrow frequency band between approximately 15 and 25 Hz. During the breeding season, the sound from many distant fin whales in tropical and subtropical parts of the world may be seen as a “hump” in this band of the ocean acoustic spectrum. Since a higher density of singing whales leads to more energy in the band, the size of this hump—the total received acoustic energy in this frequency band—may be used to estimate the population density of singing fin whales in the vicinity of a sensor. To estimate density, a fixed density of singing whales is simulated; using acoustic propagation modeling, the energy they emit is propagated to the sensor, and the received level calculated. Since received energy in the fin whale band increases proportionally with the density of whales, the density of whales may then be estimated from the measured received energy. This method is applied to a case study of sound recorded on ocean-bottom recorders southwest of Portugal; issues covered include variance due to acoustic propagation modeling, reception area, variation in whale song acoustic level and frequency, and elimination of interfering sounds. [Funding from ONR.]
Investigating the potential of a wave glider for cetacean density estimation—A Scottish study
Authors: Harris Danielle , Gillespie Douglas
Published: October 2014

A major advantage of autonomous vehicles is their ability to provide both spatial and temporal coverage of an area during a survey. However, there is a need to assess whether these technologies are suitable for monitoring cetacean population densities. Data are presented from a Wave Glider deployed off the east coast of Scotland between March and April 2014. Key areas of survey design, data collection, and analysis were investigated. First, the ability of the glider to complete a designed line transect survey was assessed. Second, the encounter rates of all detected species were estimated. Harbour porpoise (Phocoena phocoena) was the most commonly encountered species and became the focal species in this study. Using the harbor porpoise encounter rate, the amount of survey effort required to estimate density with a suitable level of uncertainty was estimated. A separate experiment was designed to estimate the average probability of harbor porpoise detection by the glider. The glider was deployed near an array of nine C-PODs (odontocete detection instruments) and the same harbor porpoise click events were matched across instruments. Such matches can be analyzed using spatially explicit capture recapture methods, which allow the detection efficiency of the glider to be estimated.
Statistical mechanics techniques applied to the analysis of humpback whale inter-call intervals
Authors: D'Spain Gerald L. , Helble Tyler A. , Batchelor Heidi A. , Rimington Dennis
Published: October 2014

Techniques developed in statistical mechanics recently have been applied to the analysis of the topology of complex human communication networks. These methods examine the network's macroscopic statistical properties rather than the details of individual interactions. Here, these methods are applied to the analysis of the time intervals between humpback whale calls detected in passive acoustic monitoring data collected by the bottom-mounted hydrophones on the Pacific Missile Range Facility (PMRF) west of Kauai, Hawaii. Recently developed localization and tracking algorithms for use with PMRF data have been applied to separate the calls of an individual animal from those of a collection of animals. As with the distributions of time intervals between human communications, the distributions of time intervals between humpback whale call detections are distinctly different than those expected for a purely independent, random (Poisson) process. This conclusion holds both for time intervals between calls from individual animals and from the collection of animals vocalizing simultaneously. although significant differences in these probability distributions occur. A model based on the migration of clusters of animals is developed to fit the distributions. Possible mechanisms giving rise to aspects of the distributions are discussed. [Work supported by the Office of Naval Research, Code 322-MMB.]
Tissue decellularization with boiling histotripsy and the potential in regenerative medicine
Authors: Wang Yak-Nam , Khokhlova Tatiana , Maxwell Adam , Kreider Wayne , Partanen Ari , Farr Navid , Schade George , Bailey Michael , Khokhlova Vera
Published: October 2014

There have been major advances in the development of replacement organs by tissue engineering (TE); however, one of the holy grails is still in the development of biomimetic structures that replicate the complex 3-D vasculature. Creation of bioartificial organs by decellularization shows greater promise in reaching the clinic compared to TE. However, current decellularization techniques require the use of chemical and biological agents, often in combination with physical force, which could result in damage to the matrix. Here we evaluate the use of boiling histotripsy (BH) to selectively decellularize large volumes of tissue. BH lesions (10–20 mm diameter) were produced in bovine liver with a clinical 1.2 MHz MR-HIFU system (Sonalleve, Philips, Finland), using thirty 10 ms pulses, and pulse repetition frequencies of 1–10 Hz. Peak acoustic powers corresponding to an estimated in situ shock front amplitude of 65 MPa were used. Macroscopic and histological evaluation revealed treatment conditions that produced decellularized lesions in which major fibrous structures such as stroma and vasculature remained intact while parenchymal cells were mostly lyzed. With further tailoring of the pulsing scheme parameters, this treatment modality could potentially be optimized for organ decellularization. [Work supported by NIH EB007643, K01-EB-015745-01, T32-DK007779, and NSBRI NASA-NCC 9-58.]
Shear waves induced by Lorentz force in soft tissues
Authors: Catheline Stefan , Pol Graland-Mongrain , Zorgani Ali , Souchon Remi , Lafon Cyril , Chapelon Jean-yves
Published: October 2014

This study presents the observation of elastic shear waves generated in soft solids using a dynamic electromagnetic field. The first and second experiments of this study show that Lorentz force can induce a displacement in a soft phantom and that this displacement is detectable by an ultrasound scanner using speckle-tracking algorithms. For a 100 mT magnetic field and a 10 ms, 100 mA peak-to-peak electrical burst, the displacement reached a magnitude of 1 m. In the third experiment, we show that Lorentz force can induce shear waves in a phantom. A physical model using electromagnetic and elasticity equations is proposed and computer simulations are in good agreement with experimental results. The shear waves induced by Lorentz force are used in the last experiment to estimate the elasticity of a swine liver sample.
Simulations of focused shear shock waves in soft solids and the brain
Authors: Giammarinaro Bruno , Coulouvrat François , Pinton Gianmarco
Published: October 2014

Because of a very small speed, shear waves in soft solids are extremely nonlinear, with nonlinearities four orders of magnitude larger than in classical solids. Consequently, these nonlinear shear waves can transition from a smooth to a shock profile in less than one wavelength. We hypothesize that traumatic brain injuries (TBI) could be caused by the sharp gradients resulting from shear shock waves. However, shear shock waves are not currently modeled by simulations of TBI. The objective of this paper is to describe shear shock wave propagation in soft solids within the brain, with source geometry determined by the skull. A 2D nonlinear paraxial equation with cubic nonlinearities is used as a starting point. We present a numerical scheme based on a second order operator splitting which allows the application of optimized numerical methods for each terms. We then validate the scheme with Guiraud's nonlinear self-similarity law applied to cusped caustics. Once validated, the numerical scheme is then applied to a blast wave problem. A CT measurement of the human skull is used to determine the initial conditions and shear shock wave simulations are presented to demonstrate the focusing effects of the skull geometry.