bluuebunny/crossref_metadata_2025 huggingface dataset:
The development of dynamic holographic acoustic tweezers
Authors: Marzo Asier , Drinkwater Bruce W.
Published: October 2018

Radiation forces due to sound waves can be used to create acoustic tweezers that can trap and manipulate matter without contact. They provide unique advantages when compared to the more established optical tweezers, such as higher trapping forces per unit input power and the ability to trap a wide range of sample materials. This paper describes the development of dynamically reconfigurable holographic acoustic tweezers that can independently manipulate multiple millimetre-scale particles. We present hardware and algorithms that create converging acoustic radiation forces at multiple locations in space with an array of phase controlled emitters. We experimentally demonstrate a 40 kHz airborne ultrasonic system and manipulate up to 25 particles simultaneously. As the acoustic field is dynamically up-dated in real-time and manipulation speeds of up 40 mm/s are shown. When considered on the scale of a wavelength, this system has similar manipulation capabilities to optical tweezers. We show experimental results that demonstrate potential applications, e.g., for assembly processes both in the micro-metre and millimetric scale, as well as positioning and orientation of multiple object which could led to biomedical applications.
Compact selective tweezers based on focalized acoustical vortices and spiraling interdigitated transducers
Authors: Baudoin Michael , Gerbedoen Jean-Claude , Riaud Antoine , Bou Matar Olivier , Smagin Nikolay , Thomas Jean-Louis
Published: October 2018

With the emergence of regenerative medicine, cell printers, and labs on chips, the contactless selective manipulation of microscopic objects such as particles, cells, or drops has become a key feature. To complete this task, acoustic tweezers appear as a tremendous alternative to their magnetic and optical counterpart. Indeed, they do not require pre-tagging of the manipulated object and they enable particles trapping with forces several orders of magnitude larger than optical tweezers at same input power. Recently, Baresh et al. [Phys. Rev. Lett., 116, 024301 (2016)] demonstrated the selective 3D manipulation of particles with a specific class of waves called acoustical vortices. Nevertheless, such manipulation was achieved with a complex transducer array coupled with a high end programmable electronics. This system is cumbersome, not compatible with microscopes and hardly miniaturizable. To overcome these difficulties, our team developed new tweezers [Riaud et al., Phys. Rev. Appl. 7, 024007 (2017)] based on spiraling interdigitated transducers (IDTs), some electrodes sputtered at the surface of piezoelectric substrates patterned by photolithography. The shape of the electrodes encodes the phase of the field like a hologram. For applications, these tweezers have many attractive features: they are selective, flat, easily integrable, and compatible with disposable substrates.
Phase-shift based expansions for material and frequency dependence of scattering and of radiation forces
Authors: Marston Philip L.
Published: October 2018

When considering the scattering of sound and radiation forces for spheres, it has historically been helpful to gain a good understanding of situations lacking dissipation. In that case the linear acoustic scattering by spheres is characterized by real partial-wave phase shifts. At low frequencies it is possible to obtain simple expansions showing the dependence of each phase shift on material properties and on frequency [P. L. Marston and L. Zhang, J. Acoust. Soc. Am. 141, 3042–3049 (2017); P. L. Marston, J. Acoust. Soc. Am. 142, 1167–1170 (2017); P. L. Marston, J. Acoust. Soc. Am. 142, 3358–3361 (2017)]. Those expansions can then be used to describe the frequency and material dependence of scattering and radiation forces for standing and traveling waves at low frequencies beyond the usual Rayleigh-scattering approximation. While spherical Bessel and Hankel functions are used in the derivation, the final expansion coefficients are expressed using algebraic functions. The derivation of the simplified series expansion for the radiation force in the traveling wave case is subtler than the standing wave case. Well-known limiting expressions are recovered in both cases. Some applications to spheres in acoustic beams are also known. [Work supported by ONR.]
Dipolar and quadrupolar mode dissipation of spherical probes spinning in vortex beam acoustical tweezers
Authors: Baresch Diego , Marchiano Régis , Thomas Jean-Louis
Published: October 2018

In this work, the possibility of simultaneously trapping and rotating single polystyrene beads, or clusters, against gravity with an ultrasonic vortex beam is demonstrated. The induced rotation of a single particle is compared to a torque balance model accounting for the acoustic response of the particle. Two dominating dissipation mechanisms of the acoustic orbital angular momentum responsible for the observed rotation are examined. The first takes place in the bulk of the absorbing particle, while the second arises as the angular momentum flux is dissipated in the viscous boundary layer surrounding the particle. Importantly, even in the long-wavelength (Rayleigh) regime, it is crucial to fully model the dissipation of the dipolar and quadrupolar vibrational modes of the particle in a slightly viscous fluid such as water. Further results suggest that, while the induced outer (Eckart) rotational flow can be neglected in water, it can play an important role in other viscous and complex fluids.
Acoustic non-diffracting tractor beams with lateral trapping
Authors: Fan Xudong , Zhang Likun
Published: October 2018

In spite of the recent exploration of non-diffracting tractor beams that pull a particle by nonconservative forces, the pulling over a long distance is not realistic without the simultaneous trapping in the lateral direction by gradient forces. Trapping of a small particle by both ordinary and vortex Bessel beams is examined in the parameter space of mass density and compressibility. The results reveal beam parameters for stable trapping. It is found that under certain conditions the trapping is independent on paraxiality parameter of the beam. The findings are validated by calculations for a variety of objects. Material parameters for the simultaneous trapping and pulling of a small particle by an ordinary Bessel beam is identified. These findings pave the way for experimental realization of stable acoustic tractor beams for a small particle.
Frequency effects in palatalization: Articulatory evidence from English
Authors: Sung Jae-Hyun
Published: October 2018

Lexical frequency and its influence on speech production have been widely acknowledged across languages and varieties, and frequency effects are so prevalent in various phonological and coarticulatory phenomena. Previous experimental studies have reported that high lexical frequency leads a greater chance of overt coarticulation (for example, more frequent overt palatalization of /d/ in would you (high-frequency) than bad you (low-frequency)). This study tests for articulatory evidence of frequency effects in palatalization by examining palatalized consonants resulted by lexical and post-lexical palatalization in English using ultrasound imaging. Comparisons of tongue contours of palatalized consonants produced by 12 native speakers of American English show that differences in lexical frequency are not directly linked to articulatory gestures. That is, speakers do not necessarily produce a greater degree of palatalization (i.e., tongue contour closer to the palate) in high-frequency words or phrases. Moreover, while most speakers maintain some degree of articulatory contrast in high- vs. low-frequency contexts, the way speakers differentiate palatalized consonants from high- vs. low-frequency items is highly individualized. The findings from this study are in line with individual variation in coarticulation, and merit further exploration in the role of lexical frequency in speech production.
Lexically conditioned phonetic variation: A test with the voicing contrast in Japanese
Authors: Tajima Keiichi , Yoneyama Kiyoko , Kitahara Mafuyu
Published: October 2018

Many lexical factors have been shown to influence phonetic realization of words. For example, studies have shown that voice onset time (VOT) of word-initial stops is shorter in high-frequency words than in low-frequency words, and is longer in words that form a voicing minimal pair, e.g., cod-god, than in words that do not, e.g., cop-*gop. The present study begins to ask whether such lexically conditioned phonetic variations are language-general, by examining productions of words in Japanese. The stimuli were two-mora Japanese minimal pairs contrasting in word-initial /k/ vs. /g/, half of which were real words, e.g., /kara/, while the other half were similar-sounding nonwords, e.g., */kapa/. Furthermore, half of the items had a lexical competitor contrasting in voicing, e.g., /kara/-/gara/, while the other half did not, e.g., /kana/-*/gana/. The stimuli were split so that each participant read only one member of each minimal pair. Twenty-four native Japanese speakers read the target items interspersed with filler items. Results showed opposite trends from those previous reported. Specifically, VOT for /k/-initial words was longer for (high-frequency) real words than for (low-frequency) nonwords, and was shorter for words that had a lexical competitor than for words that did not. [Work supported by JSPS.]
Canadian French rhotics and their continued change
Authors: Craft Justin T. , Hildebrandt Tamarae
Published: October 2018

In previous decades, Canadian French has undergone a sound change throughout Western Quebec where the apical trill [r] has moved to a production using the tongue dorsum, often being produced by speakers as a velar fricative [x, ɣ], uvular trill [ʀ], or uvular fricative [χ, ʁ] (Sankoff and Blondeau 2007, 2010). This change is argued to have been primarily driven by younger female speakers adopting the dorsal production, but change is also reported across the lifespan of older speakers. Discrepancies about whether variation in rhotic productions is the result of allophony from syllable position (Sankoff and Blondeau 2010) or whether variation is socially constrained (Milne 2012) also exist in the literature. This study presents an analysis of rhotics in harmonic words as produced by 9 speakers from Montreal, Quebec. We report preliminary results highlighting the acoustic differences in production (measuring center of gravity, F1, & F0) between speakers of different genders. These results support the hypothesis that variation is socially constrained, in addition to lending support to early reported hypotheses about the role of women as a driving force of this sound change (Sankoff et al. 2001).
Tongue bracing under bite block perturbation
Authors: Luszczuk Monika M. , Schellenberg Murray , Liu Yadong , Gick Bryan
Published: October 2018

Speech sounds have been shown to adapt quickly but imperfectly under bite block perturbation, supporting opposing acoustic vs. articulatory compensation mechanisms [Gay et al. JASA 69: 802. 1981; Flege et al. JASA 83: 212. 1998]. The present study considers whether lingual bracing may provide insight into these apparently conflicting findings. Tongue bracing against the teeth or palate is a pervasive posture maintained during normal speech [Gick et al. JSLHR. 60:494. 2017]; we aim to test whether the tongue adapts its bracing position rather than adapting each speech movement individually, providing a single, postural parametric mechanism for responding to jaw perturbation. Results of an experiment will be presented in which native English-speaking participants read aloud passages normally and under bite block conditions translating the jaw in forward, backward or lateral directions, and to varying degrees of opening. Coronal ultrasound imaging results will be reported, measuring positions of the lateral tongue for indications of stable bracing postures. Implications of these findings will be discussed for models of speech production. [Funding from NSERC.]
Lateral bias in lingual bracing during speech
Authors: Gick Bryan , Keough Megan , Tkachman Oksana , Liu Yadong
Published: October 2018

Human bodies exhibit lateral biases between many laterally symmetrical body parts (e.g., hands, feet, eyes, and ears) that increase the efficiency of behaviour and functionality of a system. We report on lateral biases observed in the tongue during speech. The tongue is bilaterally braced against the back teeth and hard palate throughout speech, but is interrupted for the production of some laterals and occasional low vowels; some evidence suggests the movement away from the braced posture may be produced by lowering one side of the tongue first and that the leading side is consistent within speaker [Gick et al. 2017, JSLHR 60(3), 494]. We report findings on lateral bias in English speakers, on its correlation with other lateral biases of the speakers, and what this may imply about the origins of this bias. Preliminary results indicate some variation, with a population-level bias (preference for one side over the other), suggesting that the bias may develop with cortical modulation in much the same way that handedness is thought to arise. [Funding through NSERC.]
Coarticulation of speech and smile movements
Authors: Chan Terrina , Taylor Ryan C. , Wong Esther Y. , Gick Bryan
Published: October 2018

Facial expressions and speech movements can impose conflicting demands on articulators. For example, the lip spreading movement associated with smiling is incompatible with bilabial closures for /m/, /b/ or /p/. Anecdotal evidence suggests this conflict may resolve as labiodental stop variants (see http://phonetic-blog.blogspot.ca/2012/03/u.html), though this discussion has been controversial [Ladefoged & Maddieson 1996, p. 18]. The simplest model of coarticulation—one of unmediated superposition of muscle activations [Gick et al., 2013, POMA 060207]—predicts that the outcome of this conflict should be determined by summing opposing forces due to competing muscle activations. If so, varying degrees of smile and varying degrees of closure force (e.g., for different stop consonants) should be expected to produce distinct outputs. Previous work suggests that closures for /m/, /b/ and /p/ vary (increasingly) in both intraoral pressure [Lubker & Parris 1970, JASA 47: 625] and muscle force [Gick et al. 2012, JASA 131: 3345]. An experiment will be presented in which bilabial stops are produced under varying smile conditions. Preliminary results indicate that labiodental stop variants occur more frequently for lower-force stops under higher-force smile conditions, as predicted. Implications for models of coarticulation will be discussed. [Funding from NSERC.]
Effects of tongue elevation speed and glottal flow control on the production of sibilant /s/
Authors: Yoshinaga Tsukasa , Nozaki Kazunori , Wada Shigeo
Published: October 2018

To clarify the effects of tongue elevation speed and glottal flow control on the production of /s/ in VCV sequence, the experimental measurements were conducted using a simplified vocal tract model. The simplified model was constructed based on five cross-sectional shapes of the vocal tract of a subject pronouncing /s/, which were measured with CT scans. The tongue elevation speed and volume flow rate at the glottal inlet of the model were controlled by using a stepper motor and an electromagnetic proportional control valve, respectively. The flow velocity at the gap between front teeth and the sound propagating from the model were measured by a hot-wire anemometer and a microphone simultaneously. By controlling the tongue elevation speed and the flow rate of the simplified model, the spectrogram of /s/ in Japanese word /usui/ was reproduced. The result of the flow measurement showed that the velocity fluctuation and the sound propagation started almost at the same time when the spectrogram was reproduced. In contrast, by lowering the tongue elevation speed, the velocity fluctuation preceded appearance of the sound generation. This indicates that the tongue elevation speed has a significant effect on controlling the sound source generation of /s/ in word pronunciation.
Individual differences and their effect on the nature of speech motor errors in younger and older adults
Authors: Dawson Katherine M. , Tiede Mark , Whalen D. H.
Published: October 2018

Older adults have been reported to have a greater propensity towards speech errors [MacKay & James, Psych & Aging, 19(1), 93–107 (2004)],but as with many age-related effects, there is considerable variability in results and a need to identify behavioral predictors. The present study employs a motor speech paradigm, whereby both younger and older adults repeated word pairs (e.g., “top-cop”) timed to a metronome in an accelerating rate task. The metronome had a steady rate for half the task (8s) and then increased at a linear rate. Participants also completed evaluations of motor speech, sensory, and cognitive abilities, so that these individual characteristics can be correlated with speech error tendencies. Articulatory data of speech movements were collected in the form of ultrasound tongue contours and lip aperture derived from facial video. Articulatory results are discussed in terms of speech error gradience in the context of previous work [Pouplier, Proc. XVth ICPhS, 2245–2248 (2003)], with emphasis on how well speakers adapt to the changing metronome rate, and how this affects error incidence in younger versus older adults.
Cepstral coefficients successfully distinguish the front Greek fricatives
Authors: Spinu Laura , Lilley Jason , Athanasopoulou Angeliki
Published: October 2018

In the current study, we explore the factors underlying the well-known difficulty in acoustic classification of front fricatives (McMurray & Jongman, 2011; Maniwa et al., 2009) by taking a closer look at the production of 29 native Greek speakers. Our corpus consists of Greek fricatives from five places of articulation and two voicing values [f, v, θ, ð, s, z, ç, ʝ, x, ɣ] produced in nonce disyllabic words before [a, o, u] in stressed syllables (e.g., [ˈθakos]). We apply a relatively novel classification method based on cepstral coefficients, previously successful with obstruent bursts (Bunnell et al., 2004), vowels (Ferragne & Pellegrino, 2010), and Romanian fricatives (Spinu & Lilley, 2016). Our method yields the best correct classification rates reported to date for front fricatives: Present study: 88%; English: 66% (Jongman et al., 2000), Greek: 55.1% (Nirgianaki, 2014). The important cues for the successful classification are the vowel following the target fricative and the second region of frication noise. Our study adds to the body of work aimed at identifying techniques for quantifying and categorizing large samples of speech. Obtaining higher classification rates than before takes us one step closer to understanding the properties of “difficult” sounds like the front fricatives.
Limitations of the source-filter coupling in phonation
Authors: Mohapatra Debasish R. , Fels Sid
Published: October 2018

The coupling of vocal fold (source) and vocal tract (filter) is one of the most critical factors in source-filter articulation theory. The traditional linear source-filter theory has been challenged by current research which clearly shows the impact of acoustic loading on the dynamic behavior of the vocal fold vibration as well as the variations in the glottal flow pulses’ shape. This paper outlines the underlying mechanism of source-filter interactions; demonstrates the design and working principles of coupling for the various existing vocal cord and vocal tract biomechanical models. For our study, we have considered self-oscillating lumped-element models of the acoustic source and computational models of the vocal tract as articulators. To understand the limitations of source-filter interactions which are associated with each of those models, we compare them concerning their mechanical design, acoustic and physiological characteristics and aerodynamic simulation. References: 1. Flanagan, J. L. (1968) “Source-system interaction in the vocal tract,” Ann. N.Y. Acad. Sci. 155, 9–17. 2. Lieberman, P., and Blumstein, S.E. (1988) Speech physiology, speech perception, and acoustic phonetics (Cambridge University Press, Cambridge, Mass). 3. Titze, I. R. (2008) “Nonlinear source-filter coupling in phonation: Theory,” J. Acoust. Soc. Am. 123, 2733–2749.
Hand gesture density in prosodically important speech regions
Authors: Danner Samantha G.
Published: October 2018

Hand movements during speech are systematically linked with a variety of “landmarks” in the acoustic speech signal, including prosodically important regions in speech. While many researchers have studied qualitative aspects of how hand movement coordinates with speech, there are few studies that consider quantitative properties of manual gestures during speech and their coordination with speech prosody. We use optical flow to automatically detect manual gesture and identify velocity peaks in the right hand movement signal. Hand gestures for six speakers are z-scored and classified into three “sizes” as a function of velocity peak magnitude. We measure whether manual gesture density—i.e., the occurrence frequency of velocity peaks—differs among regions around prosodic landmarks in the accompanying acoustic speech signal, including at speech turns, phrase boundaries, acoustic amplitude prominences, and regions containing both a pitch accent and an amplitude prominence, with respect to a baseline of all other regions of speech. Results show that manual gestures of all sizes are more frequent at phrase boundaries and at acoustically and prosodically prominent regions of speech than at turn boundaries and non-prominent speech regions. This suggests that gesture density may be a communicative component highlighting prosodically important regions of speech. [Work supported by NIH.]
Articulatory and acoustic investigations into gestures of Mandarin retroflex fricatives
Authors: Chang Yung-hsiang Shawn
Published: October 2018

This study investigates the inventory and acoustic realizations of articulatory gestures of the Mandarin retroflex (or arguably, post-alveolar) fricative /ʂ/. Tongue shapes were obtained with ultrasound images and categorized as retroflexed or bunched, in light of the literature on the North American English rhotic /ɹ/ production. Velarization, a secondary articulatory gesture of retroflex consonants, was also coded in the ultrasound imaging analysis. Lip rounding, found to be an optional enhancing gesture in Mandarin retroflexion, was identified with lip video data. The acoustic measurements included the spectral center of gravity obtained from the middle of the frication and F2 frequency measured at the onset of the vowel following the fricative. The analyses showed that the spectral center of gravity only varied as a function of the vowel context. F2 at vowel onset was affected by vowel context, velarization and the interaction of vowel context and lip rounding. The preliminary results failed to support previous speculations that the two tongue shapes in Mandarin retroflexes result in different acoustics. We consider including more acoustic measures to further explore the acoustic consequences of articulatory variations in Mandarin retroflex fricatives.
Reconstruction of the glottal pulse using a subband technique on kazoo recordings
Authors: Lucena Alexandre M. , Minami Mario , Ramirez Miguel A.
Published: October 2018

The kazoo, a wind instrument, generates its typical sound when stimulated by voiced speech. Using this instrument, this paper proposes a novel technique to recover the glottal pulse excitation of its player. We applied multiband frequency techniques to the kazoo signal to compare the results with those obtained from the corresponding recordings of an electroglottograph (EGG). With the player's management over his embouchure on the instrument, one can make recordings for spoken and singing speech as well as recitative, at the instrument’s resonator cap, which closely fit the EGG recordings. After a spectrogram analysis, it was possible to detect in the lower frequency band of the kazoo signals, the spectral envelope and, in the higher frequency band, the pitch harmonics mixed with the spectral decay of the glottal pulse. A quadrature mirror filter (QMF) was designed, providing this source-filter separation. Additionally, a reverse spectral band replication (SBR) technique was applied, which consists in recovering the lower frequency band by the demodulation of the higher frequency band followed by a total energy spectral gain adjustment, where a new signal was generated and then evaluated. At the end, a subjective evaluation, SNR, and SD measures prove the efficiency of the proposed method.
Belching as a non-lexical speech object: Evidence from pop-culture
Authors: Kidner Brooke L.
Published: October 2018

Belching is normally considered an involuntary speech-tract vocalization. When speaking, involuntary speech-tract gestures such as belching often compete with speech for articulation by our vocal apparatus. There are non-lexical paralinguistic items (i.e., “ugh”) that also convey speech meaning, but traditionally belching is not regarded as a speech object. This study presents a case where belching appears to be an intentional speech act, occurring with clearly defined parameters and not in competition with speech. Data comes from the character Rick from TV’s Rick and Morty. Transcripts were collected and compared with the audio data. 105 belches were found in the 8 episodes investigated: all belches, except 1, were not written into the original scripts or transcriptions. Acoustic analysis showed no significant disruptions between belching and speech, supporting the conclusion that belches do not compete with speech. The most frequent occurrence of belching is word-medial, after the initial segment, which is a common infixation pattern cross-linguistically. Additional acoustic analysis showed belching occurred regularly before a stressed syllable, an established pattern for infixation in English. This pattern provides evidence that these belches are behaving phonologically as para-phonemic items. The results show that belching can be intentional and behave like paralinguistic items in human language and communication.
Simultaneous estimation of array tilt and source range using broadband ship noise and a vertical array
Authors: Song Hee-Chun , Byun Gihoon , kim Jea Soo
Published: October 2018

The array invariant, a robust approach to source-range estimation in shallow water, is based on the dispersion characteristics of broadband signals in ideal waveguides. It involves time-domain planewave beamforming using a vertical line array (VLA) to separate multiple coherent arrivals (eigenrays) in beam angle and travel time. Typically, a probe signal (i.e., a cooperating source) is required to estimate the Green’s function, but the array invariant has been recently extended to a ship of opportunity radiating random signals using a ray-based blind deconvolution. Still, one major drawback is its sensitivity to the array tilt, shifting the beam angles and adversely affecting the array invariant parameter that determines the source range. In this paper, a simple optimization algorithm for simultaneous estimation of the array tilt and the source range is presented. The method is applied to a ship of opportunity (200–900 Hz) circling around a 56-m long VLA at a speed of 3 knots (1.5 m/s) at ranges of 1.8-3.6 km in approximately 100-m deep shallow water. It is found that the standard deviation of the relative range error significantly reduces to about 4%, from 14% with no compensation of the array tilt.
Mobile targets and sensor mobility in bat biosonar
Authors: Müller Rolf
Published: October 2018

Many species of echolocating bats pursue highly mobile prey such as flying insects. Target mobility poses a challenge when a prey executes escape maneuvers. In these cases, bats and their prey find themselves locked in evolutionary arms races. However, prey mobility also provides the bats with opportunities for solving the problem of detecting prey buried in clutter. This applies to active as well as passive biosonar. In passive biosonar, bats frequently listen to sounds that are generated involuntarily by the motion of a prey. In active biosonar, certain bat groups have evolved highly specialized biosonar systems to detect flying prey insects by virtue of unique Doppler signatures that are generated by the insect's wing beat. Since the Doppler shifts concerned are very small, this sensory feat requires a well-integrated suit of evolutionary specializations that include sonar signal design, cochlear filtering, representations all through the auditory system, and even adaptive behavioral control of the emitted frequencies. In addition to this complexity, bats with such a biosonar system also employ a peripheral mobility where the baffles for pulse emission and reception move rapidly during biosonar operation. It remains to be seen how these mobilities fit together to support the animal's sensory abilities.
Estimation of Shark's biomass through active acoustics
Authors: Diamant Roee , Bigal Eyal , Pinhasi Adi , Scheinin Aviad
Published: October 2018

We study sharks biomass in open-sea using non-invasive active acoustics. The importance of continuous long-term monitoring of top-predator biomass is vital in understanding the healthiness of the ecosystem. Instead of the traditional fishery data, catch-and-release methods and visual inspections, which are problematic to supply reliable statistics, we rely on acoustic tools for the quantitative estimation of the number of sharks in a given area, their size, and the evaluation of their motion patterns and behavior. We take a blind classification approach and identify sharks' related reflections from sea boundary reflections based on a track-before-detect approach. Specifically, by emitting a series of wideband acoustic signals, we create a time-delay image whose rows correspond to the received reflection response. We rely on the observation that sea boundary reflections are characterized by a random clutter-like pattern, while shark's related reflections are continuous and steady. Thus, we detect a shark in a clutter by identifying in the time-delay image continuous but curved lines whose structure meet certain limitations, namely, the shark's maximal speed and its expected carangiformmotion pattern. In this paper, we will describe our method in details and show results from a sea experiment that included a verified detected shark.
Geoacoustic parameter variations and inversion estimates with a silt-suspension theory of mud
Authors: Brown Elisabeth M. , Pierce Allan D. , Lin Ying-Tsong , Chaytor Jason D. , Siegmann William L.
Published: October 2018

Marine mud sediments can be modeled by a recent silt-suspension theory [Pierce, et al., JASA, 142, 2591 (2017) (A)], in which silt particles are embedded in a suspension of flocculated clay particles. This presentation investigates the influence on attenuation predictions from uncertainties in parameters such as the effective grain density and the distribution of grain sizes. For example, the matrix of clay flocs may effectively lower the density of silt grains and cause decreased attenuation. Effects from such parameters are determined on the regime where attenuation is nearly linear with frequency. The value of porosity is critical for specifying sound speed and attenuation in the mud layer. Porosity measurements from sediment cores can have significant uncertainty, particularly in the upper region, from the core extraction process. Inversions for porosity and other physical parameters of the silt-suspension theory are performed along a WHOI AUV track from the 2017 Seabed Characterization Experiment. Characteristics of cores guide parameter modeling and ranges for the inversions. This approach produces estimates of sound speed, attenuation, and density that are related by physical constraints. In addition, the approach allows for validity assessment of current geoacoustic mud models using measured data. [Work supported by ONR.]
Classification of acoustic and seismic signals based on the statistics of their wavelet sub-band coefficients
Authors: Smaragdakis Costas , Mastrokalos John , Taroudakis Michael
Published: October 2018

Statistical characterization of acoustic signals is a pre-processing technique aiming at the definition of signal observables, which can be used as input data in the formulation of inverse problems of acoustical oceanography aiming at the estimation of critical parameters of the marine environment. Statistical signal characterization is also a means to classify the signals and compare their properties without reference to any physical model that determines the signal observables. Thus, it can in principle be used for the comparison of the signals of any type, including seismic recordings, thus opening the area to many applications of geophysical monitoring, using signals of any type. The paper summarizes the first attempts to study the efficiency of a signal characterization method based on wavelet transform of the signal at various levels, followed by the statistical description of their sub-band coefficients. It is shown that A-stable symmetric distributions are capable of defining the statistics of these coefficients for signals used in applications of ocean acoustic tomography and geoacoustic inversions. It is further investigated if these distributions are capable of defining the statistics of seismic signals and it is shown by preliminary results, that they can indeed be considered as possible candidates in this respect.
Estimation of subbottom geoacoustic properties from offshore airgun surveys in Atlantic Canada
Authors: Warner Graham A. , Martin Bruce
Published: October 2018

This paper estimates seabed geoacoustic profiles at 14 sites offshore of the eastern Canadian coast using sound levels from a single airgun. A 210 in3 airgun was operated along two track lines at each site and a calibrated seabed-mounted Autonomous Multichannel Acoustic Recorder equipped with a single omnidirectional hydrophone recorded the airgun sounds. High-resolution bathymetry was acquired along the tracks using a ship-mounted multibeam system and conductivity-temperature-depth profiles were measured at each site. Seabed geoacoustic profiles were estimated in a non-linear trans-dimensional Bayesian inversion using energy spectral density levels at six frequencies between 10 and 320 Hz as a function of range. The inversion estimated the unknown number of subbottom layers, geoacoustic properties (including compressional and shear wave speeds and attenuations, density, and layer thicknesses), airgun source levels, a range-correction factor, and error statistics. Data were fit with error standard deviations of 0.6–5.6 dB. Convergence of the posterior probability density function was not reached within the time limits of the study so parameter uncertainty was estimated using a linearized formulation of the inverse problem centered around the model that minimized the Bayesian Information Criterion.
A primer on vector hydrophones
Authors: Armstrong Bruce A.
Published: October 2018

Vector hydrophones are used by the military to track submarines, and, more recently, by scientists attempting to measure the influence of particle velocity on the behaviour of fish. Despite being in use for decades, vector hydrophones remain poorly understood by both communities. The problem is particularly acute for those aiming to measure particle velocity because vector hydrophones do not measure particle velocity directly; rather they measure pressure difference, the force that creates particle velocity. Topics covered will be the two types of vector hydrophone and why only one works well at low frequencies, the importance of knowing the phase of the directional channels relative to each other and to the pressure hydrophone, how bearings are determined, calibration of vector hydrophones and near-field effects, the magnitude of particle velocity for typical sound pressure levels, why bigger is better for mechanical noise, why neutral buoyancy is unnecessary and undesirable, and best practice for mounting.
A bottom-diffracted surface-reflected arrival in the North Pacific observed from 15 to 3200 km
Authors: Stephen Ralph A. , Bolmer S. T. , Worcester Peter F. , Dzieciuch Matthew
Published: October 2018

Bottom-diffracted surface-reflected (BDSR) arrivals are a ubiquitous feature in long-range ocean acoustic propagation and are not predicted by existing forward models based on available bathymetric and bottom properties data. They were first identified in the LOAPEX Experiment in the North Pacific in 2004 where a BDSR from the side of “Seamount B” was observed from 500 to 3200 km range for an M-sequence centered at 75 Hz. In a follow-up research cruise in 2013, a BDSR was also observed from the side of “Seamount B” for ranges from 15 to 35 km and the same azimuth. Are the seafloor diffractors observed in 2004 and 2013 the same? Various measures of the diffractor location and their resolution are reviewed. Both diffractors fall within a 1km radius region. Elsewhere in the 2013 survey pairs of BDSRs were observed within a kilometer of each other. So it is possible that the two BDSR arrivals arise from two distinct and unresolvable diffractors. It is quite likely however that the two diffractor points are the same. The location of the 2004 diffractor is sufficient to explain the arrival times of the BDSR from the 2013 diffractor within the scatter of the data. [Work supported by ONR.]
Underwater vector sensor communication in KOREX-17
Authors: Choi Kang-Hoon , Kim Sunhyo , Choi Jee Woong , Son Su-Uk , Dahl Peter H. , Dall'Osto David R. , Bae Ho Seuk
Published: October 2018

The underwater acoustic communication channel is subject to multiple interactions with the ocean boundaries and refraction due to sound speed structure of water column, which produces significant time spread. This phenomenon is referred to as inter-symbol interference (ISI), which results in degradation of error performance. Recently, a time reversal technique has been used for reducing the ISI. However, this requires a large-size array with spatially separated receivers to obtain higher spatial diversity gain, and it becomes a limitation to its application in space-constrained environment. An acoustic vector sensor (combined pressure and particle velocity) can potentially yield a better communication performance relative to a system using only hydrophones. In this talk, communication data collected using a vector sensor known as IVAR (Intensity Vector Autonomous Receiver) during Korea Reverberation Experiment (KOREX-17) conducted in shallow water located at 34° 43′ N, 128° 39′ E on May 23–31, 2017. The characteristics of the channel as probed by a pressure-only versus combined pressure plus particle velocity system are discussed along with some performance results of a vector sensor communication system. [Work supported by the ADD(UD170022DD) and the National Research Foundation of Korea(NRF-2016R1D1A1B03930983).]
Compatibility study between building information modeling and acoustic simulation software
Authors: Erfani Kaveh , Mahabadipour Sara , Lee Joonhee , Nik-Bakht Mazdak
Published: October 2018

Geometric and non-geometric data from Building Information Models (BIM) need to be manually reconstructed in acoustic simulation software to examine building acoustic performance. This process is time-consuming, error-prone, and the accuracy of acoustic analysis results will depend on the expertise of the user. The process is also unidirectional (i.e., from BIM to the acoustic software); meaning that simulation outputs can’t be easily retrieved back to the BIM. Thus, over the last decade, several attempts have been made to integrate acoustic analysis into BIM-related software during the conceptual design phase. This paper aims to facilitate the interoperability between BIM and acoustic simulation engine by improving the information exchange between them. A case study with an educational space at Concordia University in Montreal is carried out to validate the developed system and examine the practicality and efficiency of this process in action. The paper will investigate: 1) extraction of geometry data from the BIM software; 2) enriching the BIM with data regarding acoustic absorption coefficients, via an external database; 3) calculation of acoustic qualities including reverberation time, and 4) visualization of the simulation results in the BIM software.
The ocean has music for those who ping AND listen
Authors: Benoit-Bird Kelly J. , Southall Brandon L. , Moline Mark
Published: October 2018

Sound is a key sense for animals in the ocean, including humans. The integration of passive and active acoustics in behavioral and ecosystem studies has revealed much about how ocean systems work. Here, I will discuss how the integration of echosounders with various passive acoustic approaches has contributed to our understanding to the biology and ecology of marine mammals. For example, explaining the habitat selection of beaked whales, the foraging ecology, behavior, and communication of spinner dolphins, and the ability of dolphin sonar to discriminate fish species. Careful integration of passive and active acoustics has also contributed to sonar signal design and processing approaches. A recent study of Risso’s dolphins using passive acoustic recording tags on the dolphins themselves and echosounders deployed from a ship and an underwater vehicle provided new insights into how these animals make foraging decisions, what information is available to them and when, and how changes in their prey over space and time affect their foraging behavior. The combination of passive and active acoustics is providing insight into the ecology and dynamics of predator and prey at the scale of the individual and the population.
Vertical line array tilt revealed through snapping shrimp noise
Authors: Richards Edward , Yuan Zhuqing , Song Hee-Chun , Hodgkiss William S.
Published: October 2018

The shallow-water acoustic variability experiment (SAVEX15), conducted in the East China Sea, unexpectedly recorded a great deal of snapping shrimp noise on a 16-element (56-m length) vertical line array deployed in 100-m water depths. These impulsive events can be used to find the tilt of the moored array which was caused by the strong ocean currents in the area. In this environment, the recorded snaps of bottom-dwelling shrimp within a radius of more than 500 m were largely separated from one another in time, and coherent time domain beamforming was successful in localizing snaps in time and range. The sparse and impulse nature of the snaps allowed for a simple normalization and gave tens of snap detections per second after a threshold detector. The results from the automated detector showed it was necessary to search with the beamformer over a three-dimensional space for reliable performance: (1) arrival time, (2) source range, and (3) array tilt. The results of the beamformer search in array tilt space are consistent with independent acoustic tilt measurements of the same array, showing that snapping shrimp noise in this region can provide valuable inference for the acoustic environment.
Predator-prey interactions in the Southern California Bight
Authors: Širović Ana , Baumann-Pickering Simone , Warren Joseph
Published: October 2018

The Southern California Bight (SCB) is an important foraging area for a variety of cetacean species, including blue whales and beaked whales. However, the interactions of these species with their prey (krill and deep-water squid, respectively) can be very difficult to observe. Moorings combining passive and active acoustics were deployed at two locations in the SCB in two consecutive fall and winter seasons. A High-frequency Acoustic Recording Package sampling at 200 kHz recorded the full range of baleen and beaked whale signals. The active acoustic system on each mooring included two Simrad Wide Band Acoustic Transceivers (WBAT). A bottom-mounted WBAT had an upward looking 70 kHz transducer and the one at 300 m depth had upward looking 70 kHz and 200 kHz transducers. Over the course of four months, blue whale songs and social calls were recorded on both moorings. Beaked whale echolocation clicks were commonly detected on the mooring deployed offshore, with only rare beaked whale encounters on the coastal mooring. Backscatter data indicated overlap in the presence of cetacean predators and their prey. Scattering layer dynamics were dominated by regular diel migration, with differences in scatterer abundance between mooring sites, as well as on 2–5 day time scales.
Observations of acoustic intensity fluctuations and ambient noise near the surf zone
Authors: Raghukumar Kaustubha , Scheu Kara
Published: October 2018

The recently completed Inner Shelf Direct Research Initiative (IS-DRI) experiment examined in great detail the physical oceanographic processes involved in the exchange of heat and momentum from outside the surf zone to the inner continental shelf, with a focus on features such as rip currents, fronts, and nonlinear internal waves. During this experiment, 27 kHz acoustic transmissions were also conducted with the goal of understanding nearshore acoustic fluctuations and their impact on acoustic communications and sonar performance. Acoustic intensity fluctuations are examined during two week-long periods during which intensity fades greater than 20 dB were observed. Variability spectra were found to be dominated at lower frequencies by tidal oscillations and higher frequency variability is attributed to intense nonlinear internal wave activity. Ambient noise spectra were found to be anisotropic, with low frequency spectral levels dominated by noise from wave breaking. When significant wave heights exceeded 3 m, a significant drop in spectral levels is observed, likely due to attenuation of sound by bubble plumes from breaking waves which are then ejected offshore by rip currents. Images from airplane flight missions confirmed the presence of offshore bubble plumes during swell events.
A hearing-care toolkit for young musicians: Combined use of a noise dose measurement app and acoustical manekin
Authors: Dumoulin Romain , Tordini Francesco , Voix Jeremie , Cossette Isabelle
Published: October 2018

Within a joint initiative with the Schulich School of Music at McGill University, the authors developed an original approach to raise awareness about hearing health by combining a participative assessment with a novel noise exposure risk indicator. The overall noise exposure is estimated using two complementary measurement systems addressing, respectively, the contribution determined by (i) the use of portable music players and (ii) music and non-music activities. The first system is a “listening-level measuring kiosk,” a freely accessible station on which students can place their own headphones or earphones and playback (at their preferred listening levels) music excerpts from their own playlist on an acoustical manikin. The second system is a personal, smartphone-based, “noise exposure” portable measurement device. Users start with an initial training and an audiometry screening, followed by the collection of exposure data during a 4-week assessment period. Personalized results are provided based on individual exposure profile and initial audiogram. The validation of the design of a novel noise exposure risk indicator is based on the feedback from a focus group of young musicians. This paper describes the measurement systems, assessment process, and preliminary results from the ongoing pilot studies.