bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring acoustical approach for pre-screening of building envelope airtightness level
Authors: Berardi Umberto
Published: October 2018

Air infiltration plays a significant role in designing and evaluating the performance and air quality of a building. Air leakage through an existing building enclosure can both be localized and calculated by using experimental measurement, such as blower door test system, tracer gas method, and transient approach. Estimating building air permeability through these methods can be expensive, time consuming, and weather reliant. The economical and environmental effect of air infiltration through building envelope leads towards more research on detecting air leakage locations and estimating air infiltration rate through newly introduced techniques, such as using an acoustical method. As such, in this research, a general review of airtightness detection and quantification method will be presented, especially acoustical technique which will be explored more deeply. Moreover, due to significant impact of window systems on total air infiltration through building envelope, the correlation between sound transmission loss and air permeability through seven window assemblies in an existing building will be explored in order to investigate acoustical method further. In addition, the acoustic air leakage detection method based on standard ASTM E1186 will be instigated on the experimental windows. The results reveal the negative relationship between these two phenomena.
Reactive acoustic liner design
Authors: Ramakrishnan Ramani , Van Every David H.
Published: October 2018

Acoustic treatment to reduce fan noise levels in a wind tunnel circuit consists of fibrous materials such as fibreglass or rockwool. Open cell foam materials are also used as acoustic treatments. The acoustic treatments are conventionally applied at fan tail cone regions, tunnel walls along fan diffuser section, cross-legs, test section diffuser, and nozzle contraction areas. However, conventional treatments are not possible in cryogenic wind tunnels, since bulk absorber materials with required resistivity, when operating at cryogenic temperatures, are not available. One possible solution is to design reactive silencers tuned to dominant frequencies. One such approach was used as noise control technique so as to satisfy test section noise specifications. The sound power spectrum of the compressor at different speeds were evaluated. The estimated test section sound pressure levels showed noise reduction at two dominant frequencies were required. The acoustic treatment, therefore, resulted in a double layer reactive design tuned to the two dominant frequencies. The design process will be highlighted in the presentation. The final treatment details will also be presented.
Bianisotropic acoustic metasurfaces for wavefront transformation
Authors: Cummer Steven , Li Junfei , Shen Chen , Díaz-Rubio Ana , Tretyakov Sergei
Published: October 2018

Acoustic metasurfaces are thin, engineered structures that can control the local reflection and transmission phase of acoustic waves, and thus enable a high degree of flexibility for wave manipulation. Here, we describe our recent work on so-called perfect metasurfaces, in which elements are designed that can control the local transmission and reflection amplitude and phase response of the metasurface. Controlling both the amplitude and the resulting asymmetric phase response requires a fundamentally asymmetric surface impedance for the unit cells. The resulting ideal surface properties thus have strong links to the concept of bianisotropy in electromagnetics and Willis coupling in elastodynamics. We have developed a shunt resonator-based element design that contains the needed degrees of freedom to independently control the surface impedance on both sides of the metasurface. Using this perfect metasurface design approach, we demonstrate the design and experimentally measurement of high efficiency wide-angle transmissive beam steering at levels beyond what is possible with phase control alone.
Acoustic scattering from a radially-polarized Willis-coupled cylinder
Authors: Muhlestein Michael B. , Lawrence Andrew J. , Goldsberry Benjamin M. , Haberman Michael R.
Published: October 2018

This talk presents analytical and numerical solutions to the scattering of plane waves from a Willis cylinder with radial polarization. Assuming weak coupling, the scattered field may be explicitly written as a power series expansion of the coupling strength. Using an appropriate choice of average mass density, bulk modulus, and Willis coupling, it is found that the first three scattering modes may be suppressed, providing partial acoustic cloaking using a scattering cancellation approach similar the work of Guild et al. [Phys. Rev. B, 86, 104302 (2012).]. Furthermore, we find that the Willis coupling does not need to be strong in order to achieve this mode suppression and so the weak-coupling formulation is appropriate. The scattering problem is then solved numerically using finite element analysis using the weak form of the governing equations, which is then compared to the approximate analytical model for validation. [Work supported by U.S. Army ERDC Geospatial Research and Engineering business area and by ONR.]
Guided waves at bianisotropic fluid interfaces
Authors: Wallen Samuel P. , Sieck Caleb F. , Goldsberry Benjamin M. , Guild Matthew D. , Orris Gregory , Haberman Michael R.
Published: October 2018

Willis fluids are characterized by constitutive relations that couple the pressure and momentum density to both the particle velocity and the volume strain. This effective dynamic response coupling may arise due to microstructural asymmetry, long range order, or time-varying material properties and has been shown to be analogous to electromagnetic bianisotropic media [Phys. Rev. B 96, 104303 (2017)]. In this study, we report on the existence of guided waves at the interface between two fluids when at least one displays Willis coupling. Criteria for the existence of these waves are discussed in terms of the material properties, frequency, and wave number, and expressions for the dispersion relation and rate of spatial decay away from the interface are obtained analytically. We demonstrate that interface waves are supported when one of the fluids possesses Willis coupling, in contrast to an interface between two classical isotropic fluids, which cannot support interface waves. Special cases are highlighted via numerical examples. [Work supported by ONR, NSF, the Applied Research Laboratories at The University of Texas at Austin, and the NRC Research Associateship Program.]
Rippled spectrum resolution in normal listeners: Estimates at different experimental paradigms
Authors: Supin Alexander , Milekhina Olga , Nechaev Dmitry
Published: October 2018

Rippled-spectrum (RS) signals are used for evaluation of resolution of spectro-temporal structure of sounds. Measurements of spectrum-pattern resolution imply discrimination between the test and reference signals. Therefore, estimates of rippled-pattern resolution may depend not only on the test signal but also on the reference signals. In the present study, the ripples density resolution was measured in combinations of the test and reference signals: (i) RS with phase reversals vs RS without phase reversion; (ii) RS with phase reversals vs non-rippled spectrum; (iii) RS without phase reversals vs non-rippled spectrum; and (iv) RS without phase reversals vs RS of opposite ripple phase. The spectra were centered at 2 kHz and had ERB of 1 oct and SPL of 70 dB. A three-alternative forced-choice procedure was combined with adaptive stimulation procedure. With rippled reference signals, mean ripple resolution limits were 8.9 ripple/oct (phase-reversals test signal) or 7.7 ripple/oct (constant-phase test signal). With non-rippled reference signal, mean resolution limits were 26.1 ripple/oct (phase-reversals test signal) or 22.2 ripple/oct (constant-phase test signal). Different contribution of excitation-pattern and temporal-processing mechanisms is supposed for measurements with rippled and non-rippled reference signals. [Work supported by Russian Science Foundation Grant 16-15-10046.]
Comparison of wideband and clinical acoustic reflex thresholds in patients with normal hearing and sensorineural hearing loss
Authors: Feeney M. P. , Schairer Kim , Keefe Douglas H. , Fitzpatrick Denis , Putterman Daniel , Garinis Angie , Kurth Michael , Kolberg Elizabeth , McGregor Kara , Light Ashley
Published: October 2018

Acoustic reflex thresholds (ARTs) obtained with a wideband (WB) probe and an adaptive threshold detection procedure were compared to ARTs using a clinical system. Ipsilateral and contralateral ARTs were elicited in a group of 79 adults with normal hearing (NH) and 51 adults with sensorineural hearing loss (SNHL). ARTs were obtained for both methods using activator tones of 0.5, 1.0, and 2.0 kHz and broadband noise (BBN) with a bandwidth extending to 4.0 kHz for the clinical and 8.0 kHz for the WB ART. Results were similar for ipsilateral and contralateral ARTs. Tonal ARTs with the clinical method were slightly elevated for the SNHL group for all three activator tones, but for the WB method were elevated at 2.0 kHz where the average hearing loss was greatest (47 dB HL). ARTs for BBN were higher for the clinical method than the WB method for both groups, and the difference between groups was around 5 dB for the clinical method but 12 dB for the WB method. This suggests that ARTs with the WB method and BBN activator extending to 8 kHz are a more sensitive indicator of high-frequency SNHL than the clinical method. Individual reflex patterns will also be presented.
The influence of time of hearing aid use on auditory perception in various acoustic situations
Authors: Szymanski Piotr , Poremski Tomasz , Kostek Bozena
Published: October 2018

The assessment of sound perception in hearing aids, especially in the context of benefits that a prosthesis can bring, is a complex issue. The objective parameters of the hearing aids can easily be determined. These parameters, however, do not always have a direct and decisive influence on the subjective assessment of quality of the patient's hearing while using a hearing aid. The paper presents the development of a method for the assessment of auditory perception and the effectiveness of applying hearing aids for hearing-impaired people during a short-term use. The method involves a questionnaire based on the APHAB (Abbreviated Profile of Hearing Aid Benefit) assessment questionnaire, a measure of self-reported auditory disability. The study includes additional criteria, such as measuring the number of hours and days of use of hearing aids, the degree of hearing loss and the patient's experience. A web-based application is developed to enable to carry out such an examination from any computer with access to the network. The research results show that in the first period of use of hearing aids, speech perception improves, especially in noisy environments. The perception of unpleasant sounds also increases, which leads to deterioration of hearing aid acceptance by their users.
Low-rate frequency modulation detection across the lifespan
Authors: Grose John , Buss Emily
Published: October 2018

Frequency modulation (FM) detection at a 2-Hz rate is thought to rely on temporal cues. For a 500-Hz carrier, this reliance is heightened by the use of dichotic presentation. Here, the modulator is inverted across ears such that binaural beats can cue FM. Detection acuity for FM is better in the dichotic than diotic condition, promoting the task as a measure of temporal fine structure (TFS) sensitivity. Older adults show less benefit of dichotic presentation than young adults, suggesting deficient TFS processing. This study extended the work to school-age children in order to gain a perspective of TFS processing across the lifespan. Children aged 4–10 yrs showed poorer FM detection in both diotic and dichotic conditions re young adults, and their performance was more similar to that of older adults. The dependence of the task on TFS processing was further tested by adding background noise. This reduced FM detection acuity but more for the dichotic than diotic condition. Overall, these results support the dependence of the FM detection task on TFS processing and demonstrate that such processing appears compromised at both ends of the age spectrum. [Work supported by NIDCD DC01507 (JHG) and DC00397 [EB].)
Loudness constancy in healthy older adults: Effects of sound production and visual cues of music playing
Authors: Honda Akio , Yasukouchi Ayumi , Sugita Yoichi
Published: October 2018

Loudness constancy refers to the phenomenon by which loudness remains constant in the presence of substantial changes in a physical stimulus caused by varying the sound distance. We investigated loudness constancy in healthy older adults. The degree of loudness constancy was measured using two methods of adjustment: “sound production,” by which listeners played a musical instrument as loudly as a model player, and “sound level adjustment,” by which listeners adjusted the loudness of the sound produced by a loudspeaker. The target sound was produced by the actual musical instrument performance. Sound pressure levels of the stimuli were approximately 60, 75, and 86 dB(A). The distances between the performer and the participant were 2, 8, and 32 m. In both conditions, participants were asked to produce the level of sound pressure matching the stimulus. Results show that when visual cues of musical performance are available, sound production had more robust loudness constancy than the sound level adjustment method. These results support an earlier claim that audiovisual perception and imitation are necessary for musical learning and skill acquisition.
Bilingual speech associations in phonetic representation
Authors: Cychosz Margaret , Tracy Erik C.
Published: October 2018

Listeners unconsciously index race, gender, and sexual orientation from little phonetic input. Psycholinguistic theory attributes this to a representation of language where episodic traces encode fine, speaker-specific acoustic detail. We examined this unconscious linguistic bias in a task with native English speaker participants. Participants were presented with two pictures, both of which were either Hispanic or Caucasian males. Simultaneously, they listened to a semantically-neutral English sentence spoken by either a bilingual Spanish-English male or a monolingual English male and were told to choose which pictured man said the sentence. When the auditory stimulus was bilingual speech, speakers were quicker to choose between the two Hispanic faces than between the Caucasian faces. However, when participants heard a monolingual voice, there was no difference in reaction time. In the second phase of the experiment, participants were instead presented with two different pictures, one Hispanic and one Caucasian. Listeners were more likely to associate bilingual English with the Hispanic male than the Caucasian male and vice versa (monolingual English with Caucasian male). These results suggest that listeners quickly index male Spanish-English speech, but monolingual English-Caucasian associations may not be as robust.
Quasi-phonemic vowels in Ampenan Sasak: An acoustic analysis
Authors: Pappas Leah
Published: October 2018

Phonological studies on Sasak tend to agree that Sasak has a six-vowel system /i, u, e, o, ə, a/ (Archangeli et al., n.d.; Chahal, 1998; Jacq, 1998). However, in Ampenan Sasak, a dialect spoken in the provincial capital of Mataram, it is difficult to attribute vowel quality differences of tense mid-vowels [e, o] and lax mid-vowels [ɛ, ɔ] to allophonic variation of underlying phonemes /e, o/. While lax mid-vowels tend to appear in heavy syllables and tense mid-vowels appear in light syllables (see also Archangeli et al., n.d.), there are exceptions (e.g., /baɾeh/ "late," /əmbong/ "reservoir") and several minimal pairs (e.g., /bəɾəmbok̚/ "discuss," /bəɾəmbɔk̚/ "breathe;" /koboʔ/ "levening," /kɔbɔʔ/ "play with water"). Further, speakers’ intuitions about these distinctions are unreliable. In order to understand this relationship, we elicited wordlists across 13 female speakers of Ampenan Sasak aged 18 to 48. Wordlists were balanced for syllable weight, coda segment, and syllable position and subjected to acoustic analysis. Preliminary results show that the quality of the vowel is highly affected by the weight of the syllable and the coda segment. This suggests that mid-vowels are quasi-phonemic in Ampenan Sasak (Ladd 2013). While they generally behave as allophones, this paradigm is not strictly followed.
Effects of incomplete feedback on response bias in auditory detection reanalyzed
Authors: Liu Shuang , Davis Matthew , Feth Lawrence L.
Published: October 2018

Davis (2015) reported the effects of providing incomplete feedback to listeners in a simple detection task. When feedback is limited in a detection experiment, the observer’s response criterion may deviate significantly from the optimal criterion. To approximate real-world listening conditions, a single-interval yes-no procedure was conducted with 10 feedback conditions ranging from no feedback to complete feedback. The signal was a brief 1 kHz tone; the masker was wideband white noise. The SIAM procedure (Kaernbach, 1990) was used to establish the SNR for 75% detection threshold for each listener. That level was then used in each of the feedback conditions. Davis reported a detailed descriptive analysis of the symmetry, organization, implicitness, and amount of feedback and the individual differences noted across the ten listeners. For this project, an equal-variance Gaussian signal detection framework was used to analyze the data. Model parameters were estimated via Bayesian inference. The main finding is that, as expected, complete feedback drives response criteria toward the optimum, and deviation from the optimal criterion increases as the amount of feedback decreases. While most subjects show this general trend, a few subjects maintain near-optimal behavior throughout all conditions, which is not a surprise.
Effects of corrective feedback on receptive skills in non-native contrasts: A training study in Taiwan Southern Min
Authors: Chang YinChing
Published: October 2018

The benefits of corrective feedback (CF) have been proposed in numerous L2 speech perception training studies, concerning that it provides learners with opportunities to retrieve, restructure, and consolidate their phonological representations. Moreover, different types of CF have been investigated considering that different effects will be triggered owing to involving different types of cognitive processes. This study examines the role of different types of CF in receptive skill, focusing on voiceless-voiced contrasts in Taiwan Southern Min, which is absent in Mandarin. Native speakers of Taiwan Mandarin who are also non-native listeners of Taiwan Southern Min are randomly assigned to three groups with different types of CF: Target, Non-target, and Combination of target and non-target. Preliminary results showed that among the three CF groups, identification accuracy significantly improved when participants are provided with combination CF. More generally, the results suggest that corrective feedback can play an influential role in identifying phonemic contrasts that may not occur in listeners’ native language.
Frequency-following responses elicited by a consonant-vowel with intonation
Authors: Stump Kristin M. , Jeng Fuh-Cherng
Published: October 2018

To date, two major types of acoustic stimuli have been used to evoke frequency-following responses (FFRs)—either by using a consonant-vowel or by using a vowel with intonation, but not both. The goals of this study were to (1) determine the feasibility of recording FFRs by forging a CV and intonation into one acoustic stimulus, and (2) examine the characteristics of such responses. Twelve Chinese adults (8 females, 4 males, age = 25.58 ± 4.23 years old) were recruited. FFRs were elicited by using the consonant-vowel /da/ combined with a rising intonation pattern (fundamental frequencies 85-93 Hz) for a total of 8000 sweeps from each participant. Six objective indices (consonant amplitude, consonant latency, consonant latency, frequency error, tracking accuracy, and pitch strength) were derived from all recordings. Results demonstrated that it was feasible to record the consonant, vowel, and intonation responses simultaneously. Results also demonstrated distinctive FFR trends with increasing number of sweeps for the consonant, vowel, and intonation responses. Taken together, these findings may have important implications for basic research and clinical applications.
Effects of auditory selective attention on word intelligibility and detection threshold of narrow-band noise
Authors: Teraoka Ryo , Sakamoto Shuichi , Cui Zhenglie , Suzuki Yôiti , Shioiri Satoshi
Published: October 2018

By directing auditory selective attention, humans can recognize a target sound from multiple environmental sounds. Evidence suggests that the effect of auditory selective attention is observed not only in the frequency domain, but also in the spatial domain. However, the effect of auditory spatial attention is not always observed and has been suggested to depend on the level of auditory processing. Therefore, the task dependency of auditory spatial attention was investigated by measuring the word intelligibility and detection threshold of target 1/12 octave-band noise amongst those with different center frequencies. Target and distractor sounds were presented by a loudspeaker array surrounding listeners. The target sound was presented after listeners' auditory attention was attracted to the specific direction from which the target sounds would be presented. Results showed that the word intelligibility increased when attended but the detection threshold of narrow-band noises did not change significantly. This suggests that auditory processing higher than that required for detecting a specific random noise among spatially distributed similar noises is necessary for the effect auditory spatial attention to appear. It seems interesting to pursue the lowest level, where the effects of auditory spatial attention are observable.
The acoustic and neurobological bases of the processing of vocal emotion
Authors: Scott Sophie K.
Published: October 2018

In this talk, I will briefly address the ways that the expression of emotion in the voice is affected by physiological processes (e.g., the effects of adrenaline on the vocal folds), as well an interplay of voluntary and involuntary aspects of vocal control. I will outline some behavioural and functional imaging studies of the perception of emotional voices, and the ways that emotion in the voice can be associated with some general acoustic properties (e.g., duration correlates negatively with ratings of arousal). However there is weaker evidence for a relationship between emotional valence and acoustic factors, as well as considerable evidence for emotion specific relationships between acoustic profiles and emotion ratings. I will extend this into a consideration of the sensori-motor networks recruited by different kinds of emotional vocalisations, and argue that this can often reflect more emotion specific effects, which can be linked to both affective and behavioural aspects of emotional processing.
Perception and production of vocal emotions by listeners with normal hearing and with cochlear implants
Authors: Chatterjee Monita , Sis Jenni , Damm Sara , Kulkarni Aditya M.
Published: October 2018

Informative cues for vocal emotions in speech include voice characteristics, speaking rate and intensity. For listeners with cochlear implants, voice characteristics such as pitch and vocal tract length are weakly represented in the electric signal; intensity cues are weakly to moderately preserved, and speaking rate is well represented. Our studies indicate that school-age children (6–18 years of age) with cochlear implants have significant deficits in their recognition of vocal emotions relative to normally hearing peers, similar to post-lingually deaf adults with cochlear implants. However, in contrast to the post-lingually deaf adults, children with cochlear implants showed large deficits in their productions of vocal emotions (happy/sad contrasts), measured in 1) acoustic analyses of the produced speech and 2) normally hearing listeners’ perceptions of the produced emotions. In contrast to emotions, the words and sentences produced by the children with cochlear implants were highly intelligible. Post-lingually deaf adults with cochlear implants, however, showed excellent performance in the voice emotion production task. These results suggest that the perception of vocal emotions by listeners with cochlear implants may be limited primarily by device limitations, while emotion productions in speech are shaped more strongly by early auditory experience.
Acoustic cues for vocal emotion recognition by normal-hearing listeners and cochlear implant users
Authors: Luo Xin , Pulling Kathryn
Published: October 2018

Our recent study found that cochlear implant (CI) users’ quality of life in auditory, psychological, and social functioning were predicted by vocal emotion rather than sentence recognition scores. To eventually improve vocal emotion recognition with CIs, this study investigated the acoustic cues for vocal emotion recognition by CI users with CI alone or bimodal fitting, as compared to normal-hearing (NH) listeners. Sentence duration, mean fundamental frequency (F0), and F0 range were individually normalized for emotional utterances of each talker and sentence. In two other conditions, emotional utterances were presented backward in time and with upside-down F0 contours, respectively. Perceptual results showed significant effects of subject group, cue condition, talker, and emotion. Time-reversed utterances worsened NH listeners’ recognition of all emotions except sad, while upside-down F0 contours worsened that of angry and happy. Vocal emotion recognition with CI alone only degraded with time-reversed utterances. Time-reversed utterances worsened bimodal CI users’ recognition of angry and neutral, while upside-down F0 contours worsened that of angry and happy. Bimodal CI users and NH listeners were also affected by mean F0 and F0 range normalization when recognizing happy. We conclude that natural F0 contours should be faithfully encoded with CIs for better vocal emotion recognition.
The trait-based approach as a tool to study the bio-geo seafloor system
Authors: Törnroos Anna
Published: October 2018

One of the major causes of heterogeneity on the seabed is the biology. The presence of organisms creates voids and frameworks within and on the sediment, and their behavior may layer or sort the entire seafloor. Making use of the biological information would be powerful for improving acoustics. Likewise, embracing, to a greater degree, acoustic techniques and measurements to understand the biology would be favorable. However, to tackle this bio-geo diversity in a cross-disciplinary way requires a common language and approach. Here I present and propose the trait-based approach as a way forward. Because there are simply too many species to describe and include in one model, reducing this complexity is essential and can be done by considering individuals characterized by a few key characteristics, or traits. Relevant biological traits span morphology, behavior and life-history of organisms and can be applied on single individuals and scaled up to whole communities, incorporating the density of organisms. By exemplifying the progress in benthic ecology, I outline where we currently stand, possible key traits of value for both fields and ideas on how to progress.
Effects of burrow and tube construction by infauna on sound propagation through marine sediments
Authors: Dorgan Kelly M. , Ballentine Will M. , Lockridge Grant , Ballard Megan S. , Lee Kevin M. , Wilson Preston S.
Published: October 2018

Infauna, animals living in marine sediments, modify sediment structure by burrowing, constructing burrows and tubes, and irrigating burrows. These activities can change the bulk porosity and density as well as create heterogeneity in sediment structure. We test the hypothesis that these activities alter sound speed and attenuation in sediments by manipulating homogenized sediments to mimic animal activities. Specifically, we examine the effects of burrow excavation, burrow wall compaction, burrow irrigation, and construction of tubes from shell hash on sound speed and attenuation at 100, 200, and 400 kHz. Wavelengths corresponding to these frequencies span the size of the burrows constructed, and measurements were conducted at several depths within the upper 10 cm of sediment in which infauna are commonly found. Each of these activities or functions is performed by multiple species of animals that comprise a functional group. Our results will help identify functional groups that have important impacts on sediment acoustics and will be used to interpret field data in which deviations from predicted sound speed and attenuation are correlated with different and diverse communities of infauna.
High-frequency acoustic scattering from aquatic plants and seagrass leaf blades
Authors: Johnson Jay R. , Lee Kevin M. , Ballard Megan S. , Hermand Jean-Pierre , Wilson Preston S.
Published: October 2018

Aquatic plants and seagrasses play a vital role in the littoral zone and shallow water ecosystems. They are important for carbon sequestration, habitat health, and seabed stabilization. Both aquatic plants and seagrasses are vascular plants with gas-filled internal channels, known as aerenchyma, with complex acoustic responses. Many previous field and laboratory experiments have shown that the acoustic response of vascular aquatic vegetation depends on tissue gas content, leaf blade structure, plant density, and photosynthetic activity, yet forward predictive models for acoustic propagation in aquatic plants and seagrass have not been realized. To help progress towards such a model, laboratory bistatic acoustic scattering measurements at 1 MHz were performed on aquarium raised Vallisneria spiralis. The measured results are compared to forward scattering measurements, at the same frequency, performed on naturally collected Mediterranean seagrasses Posidonia oceanica and Cymodocea nodosa. Microscopic images of leaf blade cross-sections were used to investigate the effect of tissue structure on acoustic response and nascent analytic and numerical models are presented to help interpret the measured results. [Work supported by ARL:UT IR&D, ONR, ONR Global, FNRS.]
Modeling of the power delay profile for underwater acoustic channels—Effects of out-of-plane scattering and reverberation
Authors: Jenserud Trond , Ivansson Sven
Published: October 2018

Long reverberation tails seem to be a common feature of shallow water acoustic channel impulse responses. We show examples from two significantly different environments along the Norwegian coast, and demonstrate that 2-D propagation modeling fails to reproduce the long tails observed. The continuous nature of the impulse responses and the low correlation and slow decay rates of the tails point towards reverberation as an important mechanism behind the observations. The effects of reverberation and out-of-plane scattering are then included in the modeling by employing the 3-D ray-based model Rev3D. Scattering from the sea surface and sea bottom are described by scattering-strength functions including azimuthal variation. The modeling results indicate that the long reverberation tails can be explained by 3-D out-of-plane scattering. Although the measured levels are not perfectly matched, the importance of including reverberation in the modeling is clearly demonstrated.
Model and data comparison for a three-dimensional, finite-difference, time-domain solver in Sequim Bay
Authors: Hafla Erin C. , Johnson Erick , Roberts Jesse , Raghukumar Kaustubha
Published: October 2018

Paracousti is a three-dimensional finite-difference, time-domain solution to the governing velocity-pressure equations. This program is directed at modeling sound propagation generated by marine hydrokinetic (MHK) sources in an ocean environment. It is capable of modeling complex, multi-frequency sources propagating through water and soil that have spatially varying sound speeds, bathymetry, and bed composition. Experimental sound data collected at Sequim Bay in Washington, USA, during the winter of 2017 is compared against several simulations modeled within Paracousti for a range of frequencies and receiver locations. This measurement campaign recorded ambient noise data and the sound from a source producing three-second long, sinusoidal pulses between 20 and 5,000 Hz at a depth of 3 m. Additionally, bathymetric, sanity, and temperature data for the bay were collected in order to calculate the sound speed. Data were recorded at six locations ranging in distance between 10 and 1,000 m from the source by stationary buoys. Each simulation was created to model the collected source profiles and has a total depth of 80 m, with the average soil depth occurring at 23 m, and compared via transmission losses.
Comparative study of the sound absorption coefficient of two absorbent materials with two empirical methods for low frequency
Authors: Legat Nelson L. , Silva Claudia C. , Barbieri Nilson , Lima Key F.
Published: October 2018

The equations of Delany and Bazley have been widely used in the study of the behavior of sound waves inside porous materials since 1970. However, as is known, the validity of these equations for low frequencies can produce physically inconsistent results. This work intends to evaluate the sound absorption coefficient of two types of absorbent material, one porous and one fibrous, with the Allard and Champoux's equations presented in 1992. These equations have the purpose of improving acoustic properties characterization at a low frequency. The precision of the results obtained through the two empirical methods is verified with an experimental evaluation using the modified two cavity method. The measurements are made on the impedance tube with the samples arranged in two different positions displaced from the rigid termination. Porous samples evaluated by this work were common foam and the fibrous were coconut coir fibers.
Density estimation using ocean-bottom seismometers in Cascadia
Authors: Mellinger David K.
Published: October 2018

The Cascadia Initiative placed a large number of ocean-bottom seismic sensors off the coast of the US Pacific Northwest. These sensors recorded pulsed sounds from fin whales, recorded in conditions that in many cases make it impossible to resolve the sounds from individual whales. The sounds from multiple whales, however, combine to make a distinct rise in spectral energy in the 15–30 Hz band. This received energy can be used to estimate the population density of fin whales in the vicinity of each sensor over the 4-year duration of the project. Difficulties addressed include the variable rate and intensity of fin whale vocalizations, acoustic properties of the seafloor, and differences between seismic and acoustic sensors. [Funding from ONR.]
Can whistles be used to estimate dolphin abundance?
Authors: Bazúa Durán Carmen
Published: October 2018

Dolphin whistles have been studied extensively for both wild and captive animals. They are used in the communication between individuals, to maintain contact within individuals of a herd, and to coordinate herd movements. However, little is still known on how whistles can be used to ascribe individuals. Therefore, the present study is focused on determining the stereotypy of the most frequently emitted whistles by captive bottlenose dolphins,Tursiops truncatus, housed in two different marine parks. Stereotypy was computed by changing the similarity index while classifying whistles into whistle types using Matlab BELUGA and ArtWARP. Signature whistles are an individual distinction and have a similarity index greater than 95%, therefore, allowing to assess the minimum number of whistling dolphins in a pod that emit signature whistles. This is specially important in the wild, where in some occasions, it is very difficult to assess how many individuals are present. Thus this very simple method will be useful to quantify the number of signature whistles from underwater recordings, and to relate it with the possible number of dolphins present. It is necessary to implement methods like this one to better understand how dolphins are using whistles, since acoustic communication is the most important sense in dolphin species. [Work supported by PAPIIT&PASPA-UNAM.]
Lipid-shelled microbubbles for ultrasound-triggered release of xenon
Authors: Shekhar Himanshu , Palaniappan Arunkumar , Peng Tao , Moody Melanie R. , Huang Shaoling , Haworth Kevin J. , McPherson David D. , Holland Christy K.
Published: October 2018

Xenon is a cellular protectant shown to stabilize or reduce neurologic injury in stroke. The goal of this work was to develop lipid-shelled microbubbles for ultrasound-triggered xenon release. Microbubbles loaded with either xenon alone (Xe-MB) or xenon and octafluoropropane (Xe-OFP-MB) were synthesized by high-shear mixing lipids with either 100% xenon, or 90% (v/v) xenon and 10% (v/v) octafluoropropane. The size distribution and the attenuation coefficient of Xe-MB and Xe-OFP-MB were measured using a Coulter counter and a broadband attenuation spectroscopy system, respectively. Gas chromatography/mass spectrometry (GC/MS) was performed to assess the dose and stability of encapsulated xenon. The feasibility of xenon release using 5-MHz pulsed Doppler ultrasound and 220-kHz pulsed ultrasound was tested by ultrasound attenuation spectroscopy. Co-encapsulation of OFP increased the number density, attenuation coefficient, and temporal stability of microbubbles. The GC/MS measurements revealed that 143 ± 20 μL/mg and 131 ± 33 μL/mg of xenon was loaded in Xe-MB and Xe-OFP-MB, respectively. Xe-MB and Xe-OFP-MB retained 54 ± 11% and 66 ± 1% of the xenon payload within 15 min of activation, respectively. Attenuation measurements confirmed ultrasound-triggered xenon release. These results suggest that lipid-shelled microbubbles with OFP could serve as ultrasound-triggered xenon delivery agents to attenuate cellular breakdown.
Real-time imaging-guided microbubble mediated high intensity focused ultrasound heating in an ex-vivo machine-perfused pig liver
Authors: Suo Dingjie , Juang Eric , Keller Sara , Averkiou Michael
Published: October 2018

High intensity focused ultrasound (HIFU) is used clinically for the ablation of prostate and liver tumors. More recently, HIFU has been used in the brain for locally controlled thermal treatment of nonessential tremors. However, the thermal lesion location is restricted to a small area in the tissue due to geometric and boundary limitations (avoiding skin and bone burns). Bubble-enhanced heating (BEH) allows for the use of lower power and can generate spatially controlled thermal lesions in regions not currently accessible with conventional HIFU. We have studied BEH in vitro and in a machine perfused pig liver (MPL). The MPL presents a versatile platform for perfusion and BEH studies because it is clinically relevant and allows for delivery of microbubbles under ultrasound imaging. We first applied conventional HIFU and BEH in vitro, in an enclosure with acoustic windows contaiing glycerin and microbubbles while monitoring the temperature with a fine wire thermocouple. A focused 1 MHz transducer and various clinically approved microbubbles were used. Then we applied BEH on the MPL by introducing microbubbles under image guidance. With this initial study, we have observed that BEH has resulted in 5-10x energy reduction for the formation of a reference lesion in vitro, and 3-6x in the MPL.
Study on the ultrasonic wave convergence in the medium with bone
Authors: Saeki Masaya , Bustamante Diaz Leslie V. , Nagatani Yoshiki , Chiba Ko , Mano Isao , Matsukawa Mami
Published: October 2018

Low intensity pulsed ultrasound can shorten the healing time of a bone fracture; however, the present technique does not seem not to consider the complicated ultrasound propagation in the body with bone. In this study, the time reversal technique was used to effectively converge ultrasound in the bone part. A three-dimensional distal radius model was constructed by using a high resolution-peripheral quantitative CT data (spatial resolution; 61 μm). In the simulation using Finite Difference Time Domain method, one cycle of sinusoidal ultrasound wave (1 MHz) with Hanning window was transmitted from a virtual fracture point (1 mm3). The model was surrounded by water. The propagating ultrasound waves were observed by two ring shape array transducers, coaxially placed along the bone model at the distance of 30 mm from the fracture point. Then, time reversal waves were radiated from the array transducers, considering the phase shifts and amplitudes of the observed waves in the previous simulation. The time reversal waves successfully converged near the initial virtual fracture part, telling the usefulness of the technique. In the radial-tangential plane including the point, the converged area (−3dB of maximum stress value) was 42.8 mm2.
Evaluation of wave velocity in bovine meniscus by laser ultrasound technique
Authors: Fukunaga Takumi , Kuraoka Masaki , Makino Taiki , Matsukawa Mami
Published: October 2018

Laser ultrasound technique is suitable to measure the ultrasound velocity of small samples such as meniscus. In this study, longitudinal wave velocities in bovine meniscus samples were measured using a short pulsed laser. The samples were obtained from the knee joint of bovine femurs and five cubes (3×3×3 mm3) were manually manufactured. The ultrasonic wave generated by the laser was propagated through the samples and the corresponding velocities in the axial, radial, and tangential directions were measured. The obtained velocity range was 2820–3560 m/s. The highest velocities were found in the tangential direction, followed by the velocities in the radial and axial directions, except for the samples extracted from the most posterior part of the meniscus, where the velocities were highest in the radial direction. In order to investigate the anisotropy of the meniscus, the cube samples were processed into octagonal prisms, and the velocities in the directions between tangential and axial directions were measured. The velocities observed in these directions were between the values of the ones in the tangential and the axial directions, showing the uniaxial anisotropy.
Ultrasonic characterization of porous gyroid scaffolds for bone tissue engineering: Mechanical modelling and numerical validation
Authors: Rosi Giuseppe , Nguyen Vu-Hieu , Loseille Adrien , Naili Salah
Published: October 2018

Bone substitutes can be used for pre-implant surgery in presence of volumetric bone defects. In this context, the ultrasound characterization of the bone substitute is a key issue. To this end, we model the implant as a 3D porous structure and we study its ultrasonic behavior. In the framework of artificial bone substitutes, microstructured scaffolds are widely used. In the literature, several geometrical configurations have been tested: among them, the gyroid-shaped scaffolds turn out to be an excellent choice, thanks to its ability to reproduce the behavior and the porous structure of trabecular bone. This study is focused on the mechanical modelling and numerical validation of wave propagation in a porous implant substitute. In particular, 3D finite-difference time-domain (FDTD) simulations were performed on a gyroid-shaped scaffold of saturated with water to validate the continuum mechanical model. Ultrasound excitations at different central frequencies were used in order to investigate the frequency-dependent behavior phase and group velocities.
Experiments in linear and nonlinear acoustic landmine detection
Authors: Browne Francesca M. , Korman Murray S.
Published: October 2018

When nonmetallic land mines are difficult to detect using ground penetrating radar, acoustic landmine detection is used as a confirmation sensor. Non-metallic mines include VS 1.6 and VS 2.2 anti-tank plastic landmines. In modeling nonlinear acoustic landmine detection, a 20 cm diam drum-like landmine simulant (5.08 cm height, 0.64 cm thick aluminum bottom, 0.64 cm thick acrylic top plate) was used. The flexural vibration of the acrylic top plate with the soil behaves nonlinearly. A concrete soil tank filled with dry sifted masonry sand served as an idealized granular medium. The soil tank was 57.2 × 57.2 × 22.9 cm deep (wall thickness 15.2 cm). The simulant is 3 cm deep. In airborne excitation experiments, two 8 inch diam subwoofers radiate a swept tone. A geophone (1 inch diam) measured the rms particle velocity at 28 scan locations across a 56 cm segment on the surface. The geophone-microphone frequency response (between 50 Hz and 450 Hz) vs. scan position is used to extract a response profile at any individual frequency. The lowest drum-like mode shape was strongest at 156 Hz. Nonlinear tuning curve measurements at fixed locations exhibit more softening “on the mine” vs. “off the mine.”
Demonstration of acoustic landmine detection using a clamped soil plate oscillator with airborne sound excitation
Authors: Cartron Jenna M. , Korman Murray S.
Published: October 2018

Landmine detection in gravel road beds, soil, or sand for some mines (constructed out of plastic) are difficult to detect using ground penetrating radar. In acoustic landmine detection, one would like to remotely detect a vibration profile across the surface of the soil (sand or gravel) due to the interaction between a large soil column and the localized elastic top plate. In an idealized laboratory experiment, the soil plate oscillator (SPO) apparatus models an idealization of an acoustic landmine detection experiment. The clamped circular acrylic plate (1/8 in. thick) models the top plate of a plastic buried mine while the soil column (350 g dry sifted masonry sand) supported by the plate models the burial depth. A constant current amplified sinusoidal chirp from a sweep spectrum analyzer drives two three inch diam speakers (placed above the column) generating airborne excitation. A laser Doppler vibrometer (LDV) measured the rms particle velocity at 15 scan locations across the 4.5 inch diameter soil surface in sweeps between 50 Hz and 1250 Hz. The LDV-microphone frequency response vs. scan position is used to extract a response profile at any individual frequency. These mixed mode shapes are compared for both in-phase and out-of-phase excitation.
An Acoustical STEAM event for high school students
Authors: Lechner David A. , Wilson Otto , Guan Shane
Published: October 2018

This presentation will review the methods and results of hosting our first "Acoustical STEAM" (Science, Technology, Engineering, Arts, and Math) competition as a part of the Washington DC Regional Chapter meeting of the ASA in the spring of 2018. Student teams were invited from over 50 Washington DC High School clubs and physics classes, provided a box assorted materials, and given 2 hours to create a musical video. The presentation will discuss the objectives, lessons learned, and results of the competition as well as student feedback on the event.