bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of dynamic spatial release from masking via listener head rotation
Authors: Macpherson Ewan A.
Published: December 2020

The dynamic interaural time-difference (ITD) created by listener head rotation is a potent cue for front/rear sound source localization. In principle this cue could also assist in the segregation of simultaneously presented front and rear sources, particularly when robust high-frequency spectral cues are absent. If so, head rotation might provide dynamic spatial release from masking. We assessed this in a spatial auditory attention task in which multiple different equal-intensity sequences of four spoken digits, low-pass filtered at 1500 Hz, were presented simultaneously—the target sequence from 0 or 180 deg azimuth and distractors from lateral angles of ±22.5 and/or  ± 45 deg relative to the target, but in the opposite hemisphere. On each trial, listeners either fixated towards 0 azimuth or oscillated their heads at ∼0.5 Hz with an amplitude of ∼±40 deg. Listeners reported the target sequence heard. In a majority of listeners, there was no benefit of head motion, and therefore no evidence of dynamic spatial release from masking for these stimuli. These results are consistent with those of Culling [J. Exp. Psych. 26, 1760–1769 (2000)], who found that in tone complexes with components smoothly changing in ITD, opposite movement direction for one component was not an effective segregation cue.
Real-time visual acoustic feedback for non-native vowel production training
Authors: Rehman Ivana , Das Anurag
Published: December 2020

Computer-Assisted Pronunciation Training (CAPT) software which include visual feedback have shown potential for second language (L2) learning (Mehta & Katz, 2018). However, real-time formant visualization has yet to be used for L2 learners' production of speech sounds. This project investigates the effects of real-time formant visualization on L2 vowel production training. First, a vowel visualization system is presented. In contrast with other similar tools which use a regression approach (Frostel et al., 2011), this real-time formant (F1 and F2) extraction is performed using the Parselmouth library (Jadoul et al., 2018), which then uses Praat's formant extraction algorithm (Gray & Wong, 1980) to ensure accuracy. Then, the results from a preliminary user study are reported. L2 learners (n = 5) participated in six 30-min training sessions, during which they used the system to practice their production of eight vowels. Pronunciation accuracy was analyzed by calculating Mahalanobis distances between participants' productions (produced in pre-test and post-test) and native exemplars. The analysis of this preliminary dataset showed that the use of real-time visual acoustic feedback resulted in L2 vowel production improvement, which suggests that this system could, therefore, be used as a pedagogical tool for L2 learners.
Acoustic measures of glottalization in native and nonnative English connected speech
Authors: Fang Michael , Chang Charles B.
Published: December 2020

Using perceptual coding methods, previous research on English connected speech by late-onset second language speakers (L2ers) found that L2ers produced unstressed vowel-to-vowel word junctures (e.g., go héad) as “delinked” (i.e., glottalized) at significantly higher rates than native speakers (L1ers), which could not be explained by cross-linguistic influence (CLI) from the L2ers' native language (L1). In the present study, we examined whether L2ers differed from L1ers also in degree of glottalization. Comparing high-proficiency L2ers from an L1 Mandarin background (N = 5) with L1ers (N  = 5), we collected four measures of spectral tilt (H1–H2, H1–A1, H1–A2, H1–A3) at vowel-to-vowel word junctures spontaneously produced in interview speech (N = 615 for L1ers, N = 841 for L2ers). Results showed that although junctures coded as glottalized tended to show more negative H1–H2 values (indicative of creaky phonation) than did junctures coded as not glottalized, there were no significant differences between L1ers and L2ers in any of the spectral tilt measures examined, for either glottalized or non-glottalized junctures. These findings thus suggest that although high-proficiency L2ers may glottalize vowel-to-vowel junctures at higher rates than L1ers, when they do glottalize they do so to a similar degree as L1ers, with no apparent CLI from the L1.
Comparing Mandarin-English bilinguals and English monolinguals on executive function tasks
Authors: Lam Hiu Tung Gloria , Zhao Tian , Kuhl Patricia K.
Published: December 2020

Previous studies report mixed evidence regarding bilinguals' cognitive advantage in inhibition and other executive function (EF) tasks compared to monolinguals. This study aims to replicate previous research on Mandarin-English bilinguals. Forty-four participants (22 English monolinguals & 22 Mandarin-English bilinguals) were recruited to complete four EF tasks: Simon, Stroop, Letter-Number Switching and Color-Shape Switching (Cued). The Simon and Stroop tests target inhibition by examining responses to trials with compatible versus incompatible information, and the switching task targets attention shifting skills by examining responses to trials that were repetitive versus changing. Reaction time and response accuracy were the dependent measures. In the Simon task, bilinguals responded significantly slower overall than monolinguals, although there was a significantly larger difference between compatible versus incompatible trials in monolinguals. The Stroop task revealed no group differences or interaction effects. For the switching tasks, bilinguals had a significantly higher percentage accuracy overall than monolinguals in the Letter-Number Switching task with no significant group differences found in reaction time. No significant group differences were found in both measures for the Color-Shape Switching (Cued) task. Overall, we report weak evidence of enhanced EF skills in Mandarin-English bilinguals and the results will be discussed in relation to previous studies.
The analysis of phonetic fine-tuning for less frequent nasalization developed in native Korean speakers' English production
Authors: Park Wooji
Published: December 2020

In Korean, a preceding stop sound is obligatorily nasalized by an immediately following nasal stop. Interestingly, this nasalization also occurs in English but less often than in Korean. Based on the difference in nasalization between English and Korean, this study investigated the degree and frequency of nasalization made by native English and Korean speakers when they produce the English stops /b, d, g, p, t, k/ before the nasals sounds /m, n/ in sentences. Twenty-five participants performed the task to speak 12 target items mixed with filler sentences. The results revealed that the native English speakers rarely nasalized the stops before the nasal sounds. On the contrary, the native Korean speakers generally nasalized them while each individual showed the different degree and frequency of nasalization from no nasalization to complete nasalization. It was also discovered that the voiced stops were more frequently nasalized than the voiceless stops across the Korean participants. Besides, the higher their English proficiency, the less likely nasalization appeared. It signifies that phonetic fine-tuning for less frequent nasalization in English develops among Korean speakers as they become more proficient in English.
Multilingualism and acoustic correlates of breathiness and tone in Kuy
Authors: Lau-Preechathammarach Raksit T. , Tran Melody J. , Vu Stacey H. , Zhong Cynthia
Published: December 2020

Previous work on tonogenesis has focused primarily on intergenerational differences in cue weighting (Kang 2014, Coetzee et al. 2018) and less so on other sociolinguistic and language usage factors (though see Brunelle 2009). The current study explores the relationship of these variables with acoustic measures of voice quality (H1*-H2*, H1*-A1*, H1*-A2*, H1*-A3*, CPP, F1, f0) in a modal-breathy distinction in 63 speakers of Kuy, a minority language of Thailand. Kuy speakers are historically quadrilingual in Kuy, Thai, Lao, and Khmer, but recent centralization of Thailand has led to greater Thai usage. Because Thai is tonal and lacks a voice quality distinction, speakers who use Thai more are hypothesized to weigh f0 moreheavily and other breathiness measures less heavily. We find that f0 differences are significantly larger for speakers who use Thai more, while H1*-H2*, H1*-A1*, H1*-A2*, and H1*-A3* differences are slightly, but significantly, smaller. F1 shows no effect. Unexpectedly, CPP differences are also significantly larger for speakers who use Thai more. The results suggest that increasing Thai bilingualism plays a role in shifting voice quality cue weights and, in particular, in increasing f0 cue weights, providing one mechanism by which bilingualism in a tonal language may help catalyze tonogenesis.
Bayesian framework for three dimensional, near field source localization using spherical harmonics
Authors: Metzger Thomas , Xiang Ning
Published: December 2020

Localization of sound sources relative to a receiver is of great interest in many acoustical applications. Within the near field of a spherical array, spherical wave incidence can be assumed and both direction of arrival and radial distance information can be extrapolated. This work presents a two-tiered Bayesian framework, using spherical harmonics, through which the directions of arrival and radial distance of a single, or multiple sources in the near field relative to a spherical microphone array receiver can be estimated. The first tier estimates the number of sources present in the sound field, while the second tier estimates the direction of arrival and radial distance parameters. Two models for spherical wave incidence on a spherical array, both based on spherical harmonic beamforming techniques, are formulated and analyzed. This work presents analysis of the Bayesian framework and both models to demonstrate the feasibility of model-based Bayesian inference for three dimensional source localization of one or more sources in complex noise environments.
Wallace Clement Sabine Award of The Acoustical Society of America 2020: Gary W. Siebein
Authors: Siebein Gary W.
Published: December 2020

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Processing of prosodically marked focus in a cochlear implant simulation by non-native listeners: Preliminary results
Authors: Everhardt Marita K. , Sarampalis Anastasios , Coler Matt , Başkent Deniz , Lowie Wander
Published: December 2020

Speakers can use prosodic cues to direct listeners to a specific part of an utterance. The prosodically emphasised part has linguistic focus, determined by the semantic and pragmatic context (e.g., Cole, 2015). For cochlear implant (CI) users, processing prosodically marked focus can be challenging given the degradation in fine spectrotemporal detail of the signal transmitted through the device (e.g., Başkent et al., 2016). An additional challenge can be expected for CI users listening to a non-native language. In this ongoing study, we investigate how native Dutch learners of English process prosodically marked focus in English sentences degraded by a CI simulation compared to how they process it in non-CI-simulated stimuli. These results are compared to those of native English listeners. Listeners are presented with English sentences differing in prosodically marked sentential focus and are instructed to indicate which of four possible context questions prompted the response stimulus. We expect that listeners are less accurate and less efficient for the CI-simulated stimuli compared to the non-CI-simulated stimuli and that non-native listeners are less efficient than native listeners, underlining the challenges of prosodically marked sentential focus processing in a non-native language with CI hearing.
The spoken language research laboratories (SLRL) at the University of Oregon
Authors: Baese-Berk Melissa M. , Idemaru Kaori , Kapatsinski Vsevolod , Kendall Tyler , Vaughn Charlotte , Redford Melissa A.
Published: December 2020

The Spoken Language Research Laboratories (SLRL) at the University of Oregon houses 5 integrated laboratories that focus onspeech communication. The SLRL occupies nearly 4000 square feet and includes the following state-of-the-art facilities: 10 sound-attenuated subject running rooms; 3 sound-attenuated (clinical-type) observation rooms; 2 single-wall sound booths in another sound attenuated room; 2 waiting rooms; 1 large computer lab; 2 graduate student workrooms; and 8 offices. The SLRL is further equipped with all necessary high-quality audio and audio-visual recording equipment. Research at the SLRL ranges from work on language variation and change to first and second language acquisition to the perception and production of spoken language. The labs provide a dynamic, supportive environment for collaborative research and training in experimental design, acoustic and speech movement analysis, statistical analysis, grant writing, science communication and community outreach. The SLRL is embedded in a vibrant language research community at the University of Oregon (UO) that is anchored in the Linguistics Department, but spread over multiple departments, including East Asian Languages & Literatures, Romance Languages & Literatures, and Communication Disorders & Sciences. The UO and the SLRL provide a myriad of research opportunities for students interested in spoken language behavior.
Masters course in environmental and architectural acoustics in London: A route on to our Ph.D. programme
Authors: Dance Stephen
Published: December 2020

The Masters program in Environmental and Architectural Acoustics (MSc) from London South Bank University is taught at the School of the Built Environment and Architecture. This was the first Masters course at the University and has been running for more than 40 years. The MSc program is delivered on a two and four semester basis depending if taken on a full-time or part-time basis with a two semester exemption if the applicant has already been award an Institute of Acoustic Diploma. The course is focused on the application of tools to solve real world acoustic problems in the built environment. The Masters students spend 50% of the time in the laboratory undertaken practical's which either prove or disprove classical acoustic theory using the very latest acoustics equipment. The course culminates with a thesis which the student normally undertakes over the summer. The best dissertations are then put forward for international awards and then students present their work at national or international conference
Measuring the complex shear modulus of seagrass with an iPhone: A COVID-19 experiment
Authors: Venegas Gabriel R. , Congdon Victoria M. , Torres Nicholas A. , Ballard Megan S. , Lee Kevin M. , Dunton Kenneth H. , Wilson Preston S.
Published: December 2020

The shear modulus of seagrass is an important, yet rarely reported, parameter used to study the resilience of seagrass communities to hydrodynamic disturbances, and to understand the propagation of acoustic waves through seagrass meadows. Two intact Thalassia testudinum seagrass bundles were sampled from Redfish Bay (RFB) and Lower Laguna Madre (LLM) in South Texas, transported under oxygenated salt water to Austin, Texas, where measurements were performed at the primary author's residence during the COVID-19 shelter-in-place order in May 2020. A subsample of ten seagrass blades from each bundle was chosen, and the average thickness and width of each blade were recorded. Next, an iPhone was suspended from a ledge by each blade and manually subjected to an initial angular displacement with the axis of rotation colinear to the blade length. Once released, the angular velocity of the underdamped system was measured by the iPhone's gyroscope. Finally, the angular frequency and decay rate were used to infer the complex shear modulus. The complex shear moduli reported for RFB and LLM blades are 71 + 3i MPa and 145 + 5i MPa, respectively. Results suggest epiphytic growth could both increase the loss factor and decrease the shear modulus of seagrass. [Work supported by ARL:UT IR&D.]
Vibro-acoustic analysis of noise inside vehicles
Authors: Priyadarshinee Prachee , Lim Kian-Meng , Lee Heow Pueh
Published: December 2020

The noise levels in tracked vehicles subjected to rugged terrain is an important consideration due to its effects on human health, crew fatigue and system reliability. This paper aims to predict the noise in the interior of a tracked vehicle numerically, at low frequencies. These numerical predictions of interior noise were then compared with experimental measurements. Structure-borne noise has a significant contribution in the low frequency range. The generated interior noise is dependent not only on the structural vibrations, but also on the acoustic resonance of the interior cavity. Therefore, vibro-acoustic analysis was conducted using the COMSOL Multiphysics software.
Development of the product noise rating (PNR)
Authors: Lodico Dana
Published: December 2020

A simplified Product Noise Rating (PNR) method is under development to provide noise level information on consumer products to the general public. Presenting PNR information in a simple and comprehensible manner would allow the general public to factor noise levels into their decisions and make more informed purchases. PNR includes a product noise rating scale with range-of-level indicators and a visual icon for presenting the PNR value. Previous work has determined PNR values for hair dryers and tower fans. This presentation will describe development efforts to date. Feedback is requested to help in the furthering of this method.
Influence of raciolinguistic expectations on phoneme discrimination in Spanish-English bilinguals
Authors: Dibbern Jennifer , D'Onofrio Annette
Published: December 2020

Work has demonstrated that social expectations about a speaker's identity can affect how their speech is perceived (e.g., D'Onofrio, 2019) and that interactional context, which is hypothesized to include non-linguistic cues like face or voice, may influence bilingual language processing (e.g., Grosjean, 2001). We unite these bodies of work to investigate how social information may be utilized in bilingual speech perception. In the United States, researchers have documented raciolinguistic ideologies around the use of Spanish, including that it is an indicator of Latinx identity (Rosa, 2016). To test whether racialized ideologies triggered language-specific processing strategies, thirty-one early or simultaneous Spanish-English bilingual speakers from the United States completed a visually primed phoneme discrimination task, categorizing bilabial stop continua (from /ba/ to /pa/). This design followed work demonstrating that Spanish-English bilinguals shifted their /b-p/ identification boundary as a function of the language they were told they'd be hearing (Gonzales et al., 2019). While raciolinguistic evaluations appeared to influence bilingual speech perception, they did not work the same way for each voice, suggesting the integration of multiple cues (both acoustic and social) in perception, and that the influence of raciolinguistic ideologies on speech perception may be contingent on complex aspects of the perceived speaker.
Investigating the perceptual accuracy of machine-learning generated personalized head-eelated impulse responses
Authors: Lee Ming Yang , Lawless Martin S. , Baglione Melody
Published: December 2020

An accurate pair of head-related impulse responses (HRIR) is necessary to render a realistic and immersive virtual auditory space. Since personalized HRIRs are challenging to measure, a method of using two machine-learning models to separately estimate the shape and time delays of the HRIRs based on an individual's anthropometric measurements of the head and pinnae is proposed. The investigation evaluates the perceptual accuracy of the resulting HRIRs with two subjective listening studies. First, an ABX test was conducted to determine if listeners could distinguish between auralizations made with an actual HRIR from the CIPIC database and the personalized HRIR based on the corresponding anthropometric measurements. In the second study, subjects performed localization tests in virtual reality to determine the perceptual accuracy of their personalized HRIR compared to an average HRIR. Each set of tests included one of three auralizations (noise, music, or speech) played in five source locations. Perceptual accuracy was evaluated by comparing the localization errors for the average and estimated HRIRs. The stimuli were repeated four times to investigate if subjects improved over time. The subjects were also asked to rate their listening experience to assess factors such as externalization and difficulty of localization.
Small footprint head-related transfer function measurement apparatus for binaural heads utilizing one loudspeaker
Authors: Rusk Zane T. , Vigeant Michelle C.
Published: December 2020

Apparatuses for measuring head-related transfer-functions (HRTFs) often require large anechoic spaces with one or more arcs of loudspeakers. A measurement setup to obtain the HRTF of a Brüel & Kjær HATS 4100-D binaural head was designed and implemented that utilizes one loudspeaker in a 1309 ft3 anechoic space with 18 in. wedges. By rotating the HATS along two axes, the characterization of many look directions can be achieved. The HATS can be rotated about the axis through the center of the ears via a turntable, and the yaw of the HATS can be adjusted via mounting gear on custom framing. HRTF measurements were completed using both maximum-length sequence and sine sweep signals in order to compare the two techniques. Comparisons between the measured 4100-D HRTF and the HRTF of a similar B&K binaural head will be discussed, as well as plans to use the 4100-D HRTF to compare binaural room impulse responses (RIRs) with spatial RIRs obtained with a spherical microphone array. [Work supported by a Graduate Assistance in Areas of National Need (GAANN) Fellowship.]
Co-locating remote collaborators in immersive virtual environments using telematic systems
Authors: Chabot Samuel , Mathews Jonathan , Su Hui , Braasch Jonas
Published: December 2020

The rapid shift to remote work has forever changed the dynamic of teams, which require the best tools to work collaboratively across any distance. Rensselaer is home to two immersive virtual environments, intelligent rooms with panoramic, human-scale projection screens, spatial audio loudspeaker arrays, and networks of time-of-flight and acoustical tracking sensors. This project seeks to “colocate” teams across both sites such that the experience mimics collaborating within the same room. Simple video conferencing software are rarely well-configured for large groups and do not consider users’ spatial arrangements. This approach captures ultra-low-latency video and audio feeds of each space for presentation at either end, enabling a group at each location to communicate at 1-to-1 scale with the other. A spherical microphone array tracks multiple simultaneous speakers and adjusts their spatial positions across a Wave Field Synthesis loudspeaker array, maintaining audio-visual congruency. Users at each site can use the panoramic displays to present panoramic imagery or immersive data to be explored simultaneously by each group, facilitating a collaborative immersive experience, and interactions with the screen at one site may be echoed at the other to create the appearance of a single space. [Work supported by CISL, NSF No. 1229391, Army DURIP No. 68604-CS-RIP.]
Acoustic ecological investigation of estuary habitat on Indo-Pacific humpback dolphin (Sousa chinensis) in Yunlin, Taiwan
Authors: Hu Wei-Chun , Chen Chi-Fang , Chou Lien-Siang
Published: December 2020

A sunspecies/population of Indo-Pacific humpback dolphins (IPHD, Sousa chinensis) lives in the shallow waters of Eastern Taiwan Strait. Their habitat is very close to the coast and suffering from the impact of human activities and marine pollution; the survival of this vulnerable group is at high risk. The long-term visual survey result shows that the Xinhuwei estuary has been an IPHD hot spot. Two Passive acoustic monitoring (PAM) stations with temperature sensors were deployed to detect IPHD sounds in the estuary habitat. During the past four seasons, underwater marine recorders and temperature-depth data loggers were deployed at two locations in the estuary of Xinhuwei creek, Yunlin, Taiwan. The total duration of valid data for each station is at least 19 consecutive days during each season. IPHD's click-trains and whistles were counted by a supervised detection method. The results show that the trend of click-trains (echolocation and foraging sounds) is positively correlated with sea temperature. The most active foraging behavior occurs during the daytime of summer. Whistles (social and communication sounds) are most common during spring. Except in winter, the number of click-trains and whistles are larger at the deeper measuring station (water depth of 11 m). This research was funded by Formosa Petrochemical Corporation.
Monitoring of atrial ablation using cyclic variation of integrated backscatter
Authors: Anjewierden Scott , Wazni Oussama M. , Vince D. G. , Kanj Mohamed , Saliba Walid , Fedewa Russell J.
Published: December 2020

Treatment of atrial fibrillation (AF) often relies on radiofrequency ablation (RFA) of atrial tissue. However, current treatment is associated with a >20% recurrence rate, in part due to inadequate monitoring of tissue viability during ablation. Previous work has utilized cyclic variation of integrated backscatter (CVIB) as an early indicator of myocardial recovery from ischemia. Our aim was to demonstrate the use of CVIB to distinguish normal and ablated myocardium. An AcuNav 10F catheter was used to collect radiofrequency signals from the posterior wall of the left atrium of patients before and after RFA for AF. The normalized power spectrum was obtained and integrated backscatter (IB) was extracted across two continuous heart cycles to calculate the average CVIB. Data from 14 patients demonstrated a significant difference in the magnitude of the CVIB before and after ablation (9.0 vs 6.0 dB, p < 0.001). However, no significant changes were identified when evaluating ECG-gated IB values before and after ablation: ventricular end-systole (−9.8 vs −8.6, p = 0.24), atrial end-diastole (−8.2 vs −8.6, p = 0.72) or ventricular end-diastole (−7.7 vs −8.9, p = 0.18). CVIB is able to differentiate normal and ablated myocardium and may be useful in monitoring atrial ablations.
Real-time control of radiofrequency ablation by three-dimensional echo decorrelation imaging
Authors: Grimm Peter D. , Ghahramani Z. Elmira , Dayavansha E. G. Sunethra , Swearengen Michael , Mast T. Douglas
Published: December 2020

Feasibility for real-time control of radiofrequency ablation (RFA) by three-dimensional (3-D) echo decorrelation imaging, with potential application to liver cancer treatment, is investigated. Ex vivo bovine liver is treated using a clinical RFA system (RITA 1500X generator with StarBurst probe, Angiodynamics). During ablation, pairs of echo volumes from a Siemens SC2000 scanner with a 4Z1c matrix array probe (inter-frame time 18 ms) are recorded as in-phase and quadrature (IQ) data. 3-D echo decorrelation maps are computed from these volume pairs every 11 s. Cumulative echo decorrelation, defined as the temporal maximum decorrelation for each voxel, is spatially averaged within a spherical region of interest (ROI) centered at the RF needle tip. Once the spatially averaged cumulative decorrelation within the spherical ROI exceeds a predefined threshold, ablation is halted by communication with the RF generator via a pneumatic switch connected to a microcontroller circuit. The control threshold and ROI were determined by empirically evaluating predictive performance of decorrelation in preliminary uncontrolled ablation trials. Controlled and uncontrolled ablation are compared based on correspondence of sectioned tissue histology to targeted ablation zones, receiver operating characteristic curve analysis of local ablation prediction by echo decorrelation, treatment duration, and ablation rate.
Growth and regeneration of sympathetic neuron axons induced by pulsed low intensity ultrasound
Authors: Nyiramana Jeannette , Walker Kendall , Khismatullin Damir
Published: December 2020

Over a quarter million Americans are currently living with spinal cord injuries (SCIs), costing $3 billion a year to manage [1]. SCI results in myelin loss, axonal degradation, and death of sympathetic neurons, leading to lesion formation and disruption of the primary communication pathway in the spinal cord. Low intensity ultrasound has been shown to improve axonal regeneration in the peripheral nervous system, but its effect on cells in the central nervous systems is not yet studied. The objective of this work is to investigate the growth-stimulating effects of low to mid-intensity ultrasound on axons of sympathetic neurons. To find optimal ultrasound intensities, neuroendocrine-type PC-12 cells were cultured and treated with pulsed ultrasound at varying intensities. Cells were cultured in deprived states to model a post-SCI environment, while being treated with neurotrophic factor (NGF) to induce their neuron differentiation. Images of cells were analyzed for number of cells and neurite outgrowth. Experiments with PC-12 cells found that an ultrasound intensity of 1.02 W/cm2 led to optimal neurite outgrowth when analyzing the rate of neurite outgrowth and total neurite outgrowth at the final day of experimentation. Our ultimate goal is to develop an effective, noninvasive SCI treatment based on the ultrasound technology.
Microwave-induced thermacoustic signal characteristics during pulsed microwave ablation
Authors: Evans Audrey L. , Hagness Susan C. , Ma Chu
Published: December 2020

Microwave ablation (MWA) is a minimally invasive thermal therapy in which an interstitial antenna delivers microwave power locally to diseased tissue to cause cell death. Thermoacoustic (TA) signals can be generated with internally pulsed microwave energy that simultaneously ablates tissue. When pulsed microwave energy is absorbed by tissue, the tissue undergoes an incremental temperature rise which leads to thermoelastic expansion and the generation of an acoustic wave that can be detected by ultrasound transducers. The characteristics of the TA signals are linked to features of the local ablation environment from which they are generated, and thus can be exploited for ablation monitoring. In this experimental and computational study, we examine the fundamental characteristics of TA signals generated from within the ablation zone and observe how the TA signal changes as the ablation zone evolves. We performed pulsed microwave heating experiments in non-coagulating and coagulating liquids and measured the resulting TA signals. We also performed multiphysics simulations of the MWA process that encompass the electromagnetic, thermal, and acoustics physics. This study provides insights into TA signal generation and propagation during MWA and establishes the feasibility of using the TA signals for ablation monitoring.
An explanation of the decrease in the earplug noise reduction when combined with an earmuff on an acoustic test fixture
Authors: Luan Yu , Doutres Olivier , Nélisse Hugues , Sgard Franck
Published: December 2020

For people working in high noise level environments, typically above 105 dBA, double hearing protection (DHP) systems (earplugs worn in combination with earmuffs) are always recommended. However, it is very difficult to predict the DHP overall sound attenuation due to the complexity of the system. A recent experimental study has shown on human subjects and an acoustic test fixture (ATF) that the noise reduction (NR) of the earplug decreases considerably when an earmuff is worn over it but the reason is still not fully understood. In this work, specially designed experiments using an ATF are proposed in order to explain this observation. The focus is put on the NR of the single earplug and that of the earplug in the DHP system. The respective effects on the DHP attenuation of various sound transmission paths involved in the system (both air-borne and structure-borne) are analyzed by modifying the system coupling conditions or controlling the sound pressure level under the earmuff. This work will help better understand the interactions between the system components and will provide the grounds for developing a prospective numerical model to predict the sound attenuation of a DHP system.
Flexible transportation of microparticles and cells in phononic crystal based acoustofluidic channel
Authors: Cai Feiyan , Li Fei , Liu Zhengyou , Zhang Likun , Zheng Hairong
Published: December 2020

As one of the prominent technologies for non-contact manipulations, acoustic tweezer devices have used both standing waves and sound beams to trap particles at a fixed point, i.e., static positioning. However, dynamic manipulations of microparticles, cells, and living organisms are demanded in various micro/nanotechnologies, such as biomedical sensors, imaging devices, diagnostic tools, etc. The dynamic manipulation of microparticles in real-time requires time-variant acoustic fields. Here, a novel way for three-dimensional dynamic manipulation of microparticles and cells in the acoustofluidic channel is proposed by using a phononic crystal plate that modulates the acoustic field in a desired manner. This approach is superior to the conventional dynamic manipulations based on tuning phases of standing waves or moving sound sources. The phononic crystal based manipulations benefit from the resonant excitation of specific modes in the phononic crystal plate. The switch between different resonant modes in the phononic crystal plate enables the flexible switching between trapping and transportation, sets up a basis for completely flexible manipulation of microparticles in acoustofluidic channel.
Three-dimensional trapping and assembly with synchronized spherical acoustical vortices
Authors: Gong Zhixiong , Baudoin Michael
Published: December 2020

Micro-objects and micro-organisms trapping and assembly with acoustical tweezers would open new horizons in microrobotics and microbiology, e.g., selective cells fusion and aggregation. Our previous work [Gong and Baudoin, Phys. Rev. Appl. 12, 024045 (2019)] demonstrates theoretically in two dimensions (2-D) the possibility to trap and assemble small particles compared to the wavelength with synchronized acoustical tweezers based on cylindrical acoustical vortices. However, there is no trap in the beam's propagation direction since the cylindrical acoustical vortex is progressive along their central axis, leading to the fact that particles are only pushed or pulled (not trapped) in this direction and hence are mainly limited to 2-D operations. In this work, we extend our previous analysis and show theoretically that particles can be trapped and assembled in three dimensions with synchronized spherical vortices. We show that the particles can be approached both laterally (similar to the 2-D synchronized cylindrical vortices) and axially (extra to the 2-D case) and we determine the maximum assembly speed by balancing the critical radiation force and the Stokes’ drag force. These theoretical results provide guidelines to design selective acoustical tweezers able to trap and assemble small particles in three dimensions.
Estimation of the category of notch frequency bins of the individual head-related transfer functions using the anthropometry of the listener’s pinnae
Authors: Iida Kazuhiro , Nishiyama Orie , Aizaki Tsubasa
Published: December 2020

An authentic approach to present three-dimensional acoustical sensation to everyone is to provide head-related transfer functions (HRTFs) that are exactly adapted to each listener. This approach is called the individualization of HRTFs. In order to generate individualized HRTFs, the present study proposes a modeling method of HRTFs that extracts the frequency bins in which spectral notches (N1 and N2) are included. The notch frequency bins for N1 and N2 were classified into two categories based on the just noticeable difference in notch frequency with regard to the vertical angle perception of a sound image. Then, discriminant analyses were carried out as objective variables of the category of each of the N1 and N2 frequency bins and as explanatory variables of ten anthropometric parameters of pinnae. The results show that the categories of N1 and N2 frequency bins can be estimated with accuracies of 78.9% and 77.8%, respectively.
Windowing technique in determining the importance of sound propagation through vehicle glazing systems
Authors: Saha Pranab , Deshpande Satyajeet , Fisher William , Bhatia Vikram
Published: December 2020

The glazing system of a vehicle plays a very significant role in developing an efficient sound package system. However, in developing the sound package treatments in the vehicle, although one studies the importance of various paths through which sound is travelling, often the glazing system is overlooked. This paper discusses the windowing technique methodology that is used for identifying the importance of paths and the setup that was used to determine the importance of individual glazing units and the collective glazing system in the overall sound propagation through the body panels of a SUV. Results show that a significant amount of sound energy propagates from outside to inside the vehicle through all glazing units combined than through the rest of the vehicle.
A novel tool for automated assessment of listener transcripts in speech intelligibility studies
Authors: Bosker Hans Rutger
Published: December 2020

In the field of speech perception, many studies assess the intelligibility of spoken stimuli by means of verbal repetition (“repeat back what you hear”) or transcription tasks (“type out what you hear”). The intelligibility of a given stimulus is then often expressed in terms of percentage of words correctly reported from the target stimulus. Yet scoring the participants’ raw responses for words correctly identified from the target stimulus is a time-consuming task, and hence resource-intensive. Moreover, there is no consensus on what protocol to use for the human scoring, limiting the reliability of human scores. The present paper evaluates various forms of “fuzzy string matching” between participants’ responses and target sentences as automated metrics of listener transcript accuracy. Fuzzy string matching is identified as a consistent, efficient, and accurate method for automated assessment of listener transcripts, as evidenced by high correlations with human-generated scores (r = 0.922) and a strong relationship to acoustic markers of speech intelligibility. Thus, fuzzy string matching provides a practical tool for assessment of listener transcript accuracy in large-scale speech intelligibility studies.
Development of sonar simulation program for synthetic aperture processing with arbitrary sensor motion
Authors: Kim Sea-Moon , Byun Sung-Hoon
Published: December 2020

Due to high image resolution capability, the synthetic aperture sonar (SAS) is widely used for search and identification of underwater objects on seafloor. However, the image resolution of SAS is greatly influenced by sensor array movement and it is very important to estimate precise sensor positions. In order to verify SAS signal processing performance when themotion is out of the planned route, a simulation software based on MATLAB script has been developed which can simulate any arbitrary motion of transmitters and receivers. In addition, the motion and attitude of targets can be described by any arbitrary function of time for future study on identification of moving targets. To describe as close to an actual SAS system, the directivity patterns of transmitters and receivers can be applied with any arbitrary shape. It is also possible to have any reflectivity pattern of targets which is a function of incident and scattered angles with respect to the axis fixed on the targets. In this presentation SAS processing results with various situations as well as verification of the software will be presented. [This work is financially supported by the research project PES3570 funded by KRISO.]
Obtaining far-field spherical directivities from arbitrarily shaped arrays using the Helmholtz equation least-squares method
Authors: Bellows Samuel , Leishman Timothy W.
Published: December 2020

Commonly, directivities of sound sources are measured using surrounding spherical arrays. However, in some cases, such as when measurement hardware is limited, or when an array shape would ideally conform to the radiating object's geometry, obtaining spherical far-field directivities using an arbitrarily shaped array could be useful. This work illustrates how the Helmholtz equation least-squares method applies to accomplish this task. Both numerical models and the measured directivities of various guitar amplifiers validate the technique.
Low frequency sound absorption in the Arctic Ocean: Update on the impact of ocean acidification
Authors: Browning David , Herstein Peter
Published: December 2020

The principal mechanism for low frequency sound absorption in seawater is a boron relaxation reaction that is pH dependent: the lower the pH; the lower the absorption. In 1987, Mellen et al. [J. Acoust. Soc. Am. 82, S30 (1987)] extensively computed the low frequency absorption in the Arctic Ocean. Since that time the carbon dioxide (CO2) level in the atmosphere has been continually increasing, and in 2014 Browning and Herstein reported the corresponding change in ocean pH and resulting change in seawater sound absorption that had occurred [J. Acoust. Soc. Am. 135, 2306 (2014)]. This paper now provides a further update to the present time on the changing Arctic Ocean low frequency sound absorption and indicates what the result might beif the United Nations' goal of reaching equilibrium in 12 years is met.
Clay pots in Ottoman architecture: A discussion on their acoustical employment
Authors: Atay Gülnihan , Sü Gül Zühre
Published: December 2020

The employment of the clay pottery as an acoustical element first appeared in Vitruvius’s texts in the antiquity. Up to this date, their precise contribution to the acoustic quality of the space has remained vague despite many studies examining their employment as cavity resonators in medieval liturgical architecture throughout Europe and Near East. They are also observed in the substantial number of structures that belong to the Classical Ottoman Architecture, some of which were designed by Sinan, the architect laureate of Ottoman Empire. One of his works, Süleymaniye Mosque, which contains substantial number of pots in its grand dome exhibited significantly high reverberation times especially in the low frequency ranges in the recent acoustic measurements. Such long decays set forth the question whether the clay pots were designed to act as Helmholtz resonators that would control the low frequencies in their original state. Thus, this study aims to exhibit the state of the art of the clay potteries utilized as cavity resonators in the Ottoman Architecture and set a ground to compare their utilization with their contemporaries around the world as well as initiating further studies on the working principles of the cavity resonators in Ottoman Architecture.
Design of efficient low-frequency sound absorbers using an array of Helmholtz Resonators
Authors: Rajendran Vidhya , Méndez Echenagucia Tomás I. , Piacsek Andrew A.
Published: December 2020

This paper describes the design process of a low-frequency sound absorptive panel composed of differently tuned Helmholtz Resonators. Given the size and fabrication constraints relevant for applications in the building sector, we focus on cylindrical and spiral resonators with embedded necks that are space-efficient and can achieve perfect absorption. Apart from the design of an individual resonator, the design process involves modifying the mutual interaction between the resonators to improve the absorption performance of the whole panel. Additional resistance in the necks is considered as a means to shift the absorption towards lower frequencies. Panel sizes of 0.2 m × 0.2 m loaded with 9 or 16 resonators were tested in an impedance tube built specifically for measuring low-frequency absorption. The measured absorption performance of these panels is consistent with the theoretical predictions. Of particular interest is the impact of the arrangement of the resonators in the panel on its absorption performance, which has been overlooked in the theoretical models. As predicted, the experiments show a shift in absorption performance towards low-frequencies with the inclusion of neck embedding and additional resistance in the neck, and without changing the geometry of the panel.
Significance of middle ear model for prediction of metabolic exhaustion of the auditory system
Authors: Zagadou Brissi
Published: December 2020

Modern day military noise is complex, involving irregular impulses riding on top of moderate continuous background noise. An accurate prediction of injury from complex noise exposure requires both a cochlear metabolic exhaustion (ME) model and an accurate middle ear model (MEM), accounting for acoustic reflex (AR) and annular ligament (AL) nonlinearities. An end-to-end biomechanical model including a ME model was developed that established a good correlation between the outer hair cell energy deficit (OHC-D) outcomes and the temporary threshold shift (TTS) data from chinchilla complex noise exposure, explained the data collected, and provided insights on the effect of complex noise exposure on outcomes, including the effect of inter-pulse Interval (IPI), shot sequence, and background noise. Literature data were used to derive the open ear and middle ear transfer functions (TF). In this paper, the model results are discussed with an emphasis on the MEM component. The differences in the end-to-end model results are compared between the new MEM and a MEM adopted from the improved AHAAH-ICE model that includes the AR and AL nonlinearities, with model parameters adjusted for chinchilla. The results show that the TFs from the two MEMs cannot be matched using mere parametric optimization, due mainly to the fact that the chinchilla middle ear is rather tuned to the higher frequencies compared to that of human. There is a need for an improved MEM for the chinchilla middle ear TF including AR effects.
Testing the fit of a new standard for hearing protection fit testing
Authors: Fackler Cameron J. , Wells Lauraine L.
Published: December 2020

Systems that test the fit of hearing protection devices (HPDs) on individual users are an increasingly popular tool in hearing conservation. ANSI/ASA S12.71-2018, American National Standard Performance Criteria for Systems that Estimate the Attenuation of Passive Hearing Protectors for Individual Users, is the first standard worldwide for HPD fit-test systems, referred to as field attenuation estimation systems (FAESs). The S12.71 standard specifies a variety of system performance requirements that may be voluntarily adopted by the manufacturer of a FAES. It also specifies experimental procedures to evaluate FAES performance and uncertainty. This presentation gives an overview of the requirements outlined in S12.71-2018 and shares our experiences in evaluating a commercially available FAES for compliance with this standard.