bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the human impact caused by the sound of wind turbines
Authors: Palmer William K.
Published: May 2015

A mystery surrounds the human impact reported by those with wind turbines in their environment. “PubMed” identifies 23 papers for “wind turbine human health.” A dose-response relationship between exposure to sound, annoyance, and sleep disturbance is generally accepted. Self-reporting identified other impacts that commenced or increased with wind turbines operation. Recent articles repeat that no peer-reviewed papers show other links than annoyance and possibly sleep disturbance, and suggest that wind turbine visibility, negative attitudes, fear, or lobby groups cause adverse reporting, but provide no evidence dispelling impacts. Many argue acceptability of annoyance is a social measure set by government. Meantime, the Government of Canada “Wind Turbine Noise and Health Study” presented findings of an association between increasing noise from wind turbines and annoyance, but no found no evidence linking exposure to wind turbine noise to any of the self-reported illnesses, and no association between wind turbine noise and measures of stress, sleep quality, or significant changes in quality of life. Neglected in all of this, those who have been adversely impacted believe no one is listening. This paper takes up their position, to examine other acoustic factors to generate a hypothesis for cause of the human impact.
Incorporating atmospheric uncertainties into estimates of the detection capability of the IMS infrasound network
Authors: Le Pichon Alexis
Published: May 2015

To monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), a dedicated network is being deployed. Multi-year observations recorded by the International Monitoring System (IMS) infrasound network confirm that its detection capability is highly variable in space and time. Today, numerical modeling techniques provide a basis to better understand the role of different factors describing the source and the atmosphere that influence propagation predictions. Previous studies estimated the radiated source energy from remote observations using frequency dependent attenuation relation and state-of-the-art specifications of the stratospheric wind. In order to account for a realistic description of the dynamic structure of the atmosphere, model predictions are further enhanced by wind and temperature error distributions as measured in the framework of the ARISE project. In the context of the future verification of the CTBT, these predictions quantify uncertainties in the spatial and temporal variabilities of the IMS infrasound network performance in higher resolution, and will be helpful for the design and prioritizing maintenance of any arbitrary infrasound monitoring network.
Absorption of infrasound and acoustic-gravity waves in the atmosphere
Authors: Godin Oleg A.
Published: May 2015

Long-range propagation of infrasound and acoustic-gravity wave fields in the middle and upper atmosphere are strongly affected by air viscosity and thermal conductivity. To characterize the wave dissipation, it is typical to consider idealized environments, which admit plane-wave solutions. This paper presents an asymptotic approach that relies instead on the assumption that spatial variations of environmental parameters are gradual. Unlike the traditional approach, the asymptotic theory allows one to derive AGW dispersion equations in a consistent manner for a wide range of scenarios and to describe the wave attenuation more realistically. Realistic assumptions about the atmosphere are found to lead to rather different predictions for absorption of atmospheric waves than the plane-wave solutions. Wind speed and wave frequency appear only through the intrinsic wave frequency in the dispersion equation, including the terms that describe the effects of viscosity and thermal conductivity. It is found that the Sutherland-Bass model of infrasound absorption should be modified to account for wind-induced absorption anisotropy, which arises from deviations of the intrinsic frequency from the wave frequency that is observed in a stationary reference frame. The anisotropy is expected to result in a significant decrease in the predicted attenuation of thermospheric returns.
Auditory/visual distance perception
Authors: Zahorik Pavel
Published: May 2015

A considerable body of research suggests that the perception of sound source distance exhibits systematic biases. The distances of far sources are progressively underestimated, but near sources are overestimated. Such biases are typically not observed in vision, where perceived distance is found to be highly accurate under natural viewing conditions in which a variety of visual distance cues are available. Relatively little is known about how distance information from both auditory and visual modalities is combined in the perception of distance, however. This is surprising, given that auditory/visual aspects of directional perception have been extensively studied, primarily in relation to the “ventriloquist effect.” Here, two recent experiments on auditory/visual distance perception are summarized. The results from both suggest that not only is perceived distance less accurate in the auditory modality than in vision, but it is also considerably less precise. These results explain why visual information, when available, appears to dominate auditory information in the perception of distance. [Work supported by NEI.]
Individual differences in real-time processing of audiovisual speech by preschool children
Authors: Grieco-Calub Tina M. , Olson Janet
Published: May 2015

Visual speech cues maximize speech perception for adults in challenging listening environments: reliance on visual speech increases with greater auditory degradation. Young children, however, may be limited in audiovisual speech perception because of the cognitive costs associated with multimodal processing. In this study, real-time speech understanding was measured in preschool children (N = 33, 30–48 months of age) using eye-tracking methodology in the absence (quiet) or presence of two-talker babble and in the absence (auditory-alone, AO) or presence of audiovisual (AV) speech cues. On each trial, children were instructed by a female speaker to look at one of two objects projected onto a large screen. Speech processing was quantified by how quickly children fixated the target object (reaction time, RT) and overall accuracy of target-object fixation. Visual benefit was calculated as the difference in performance between the AO and AV conditions. Analyses revealed negative correlations between RTAO and RTAV in both the quiet and two-talker babble conditions: visual speech facilitated speech processing in children with slow RTAO, but not in children with fast RTAO. Results suggest that visual speech facilitates speech perception in preschool children, but is likely dependent on children’s processing efficiency of the AO speech signal.
Considering, capturing, and representing the visual environment in noise perception studies
Authors: Carter J. Parkman
Published: May 2015

Despite studies which show the profound influence of visual environments on aural expectations and perceived noise annoyance, popular noise mapping techniques continue to reflect only one dimensional sound pressure level metrics. Contextual factors, which significantly influence noise perception, can be gleaned from the visual environment, but there are no established protocols for documenting and representing salient visual features. Techniques for capturing and representing the visual environment will be discussed, which can address the intrinsic differences between audio and photographic capture in terms of dynamic range and spatial resolution. Immersive audio and video projection techniques which are currently being developed at RPI’s Collaborative Research Augmented Immersive Virtual Environment (CRAIVE) Lab will also be presented. These large scale multi-modal presentation strategies significantly improve efforts to conduct subject studies in environmental noise perception and assessment.
Visual influence on the subjective impressions of urban soundscapes
Authors: Adams Tyler
Published: May 2015

Audio recording is a common method for evaluating subjective impressions of soundscapes, which is useful because the same information can be reproduced and presented to subjects in a controlled environment. This study was conducted to determine what impacts visual information might have in the subjective evaluations of urban soundscapes. Audio of urban environments was recorded using binaural and multi-channel methods; video was simultaneously recorded using a single channel digital camera. The soundscapes were reproduced for subjects in a laboratory environment with and without the accompanying videos. The data gathered from evaluations made in the laboratory were also compared with evaluations conducted in situ to determine the degree to which impressions might change in a controlled environment.
Noise identification, modeling, and control in mining industry
Authors: Tripathy Debi Prasad , NANDA SANTOSH KUMAR
Published: May 2015

Prolonged exposure of miners to the high levels of noise in opencast and underground mines can cause noise induced hearing loss and non-auditory health effects. To minimize noise risk, it is imperative to identify machinery noise and their impacts on miners at the work place and adopt cost effective and appropriate noise control measures at the source, path, and at the receiver. In this paper, authors have summarized the noise levels generated from different machineries used in opencast and underground mines and elaborated on frequency dependent noise prediction models, e.g., ISO 9613-2, ENM, CONCAWE, and non-frequency based noise prediction model VDI-2714 used in mining and allied industries. The authors illustrated the applications of innovative soft computing models, viz., Fuzzy Inference System [Mamdani and Takagi Sugeno Kang (T-S-K)], MLP (multi-layer perceptron, RBF (radial basis function) and adaptive network-based fuzzy inference systems (ANFIS) for predicting machinery noise in two opencast mines. The paper highlights the developments and research conducted on effective noise control measures being adopted for mining machineries and implemented in mines to minimize the noise menace so that noise levels generated in mines are within the prescribed noise standards and rules.
Comparison of noise reduction values for fit tests and work in coal mines
Authors: Takacs Brandon C. , Guffey Steven E. , Wu Mingyu , Michael Kevin
Published: May 2015

At present exposure limits, one in four workers will develop a permanent hearing loss as a result of mining coal (Prince 1997). Mine Safety and Health Administration (MSHA) inspectors found in the period of 1986-1992 that approximately 25% of coal miners' daily noise doses exceeded MSHA's PEL. Virtually all mines have hearing conservation programs and virtually all miners are issued and told to wear either ear muffs or ear plugs. Nevertheless, miners still have a high rate of noise induced hearing loss (NIHL). An important question is to what degree the ineffectiveness of hearing conservation programs is due to failure of miners to wear muffs and plugs properly when they are needed and how much is due to inadequacies of hearing protectors. If the former is important, can technological innovations provide means to improve use of muffs and plugs. If the latter is important, can individual fit-testing improve noise reduction (NR) values achieved by miners. A related issue is whether fit-testing in an office environment adequately predicts NR values achieved during work if non-wearing times are excluded. To address those issues, WVU is conducting studies in a lab and in coal mines that primarily involve measuring sound levels in the ear (SPLear) concurrently with sound levels at the shoulder (SPLsh), allowing computation of NR values for protectors.
Jackhammer chisel damper
Authors: Scarton Henry A. , Wilt Kyle R.
Published: May 2015

This paper will present the performance of a rugged Coulomb Friction damper for a Jackhammer chisel. The predominant source of high intensity airborne noise from a pneumatically muffled jackhammer is the ringing resulting from impacting the undamped chisel, which radiates airborne sound from the impacts of the hammer exciting the transverse bending modes. A simulated steel chisel moil point was constructed with geometric properties similar to a jackhammer chisel and designed so as to survive the severe acceleration impacts from the reciprocating hammer. Anechoic tests of the chisel and it damped equivalent indicate that the sound pressure level for the undamped chisel due to longitudinal impact was 86.8 dB linear (re to 20 Pa) with the strongest ring tone at 1.6 kHz and harmonics; the sound pressure level for the damped chisel with identical axial impacts was reduced by 13 dB to 73.5 dB with severe reduction of chisel ring.
Vowel context effects on the spectral dynamics of English and Japanese sibilant fricatives
Authors: Reidy Patrick F. , Beckman Mary E.
Published: May 2015

Previous analyses of vowel context effects on the sibilant fricatives of English (/s, ʃ/) and Japanese (/s, ɕ/) have focused on spectral properties computed from a limited number of time points, e.g., frication midpoint or vowel onset. However, the spectra of sibilants vary temporally; thus, it is worth considering how their spectral dynamics vary across vocalic contexts. Vowel context effects were investigated with respect to the trajectories of three psychoacoustic measures computed across the timecourse of native, adult speakers' productions of word-initial, pre-vocalic sibilants. Psychoacoustic spectra were computed from 10 ms windows, spaced evenly across the frication, by passing each window through a bank of gammatone filters, which modeled the auditory system's differential frequency selectivity. From these psychoacoustic spectra, the peak frequency, excitation-drop (difference between maximum high-band and minimum low-band excitation), and the half-power bandwidth of the peak were computed. In Japanese, the peak frequency and the excitation-drop trajectories showed effects of vowel height—the trajectories for high (vs. mid and low) vowel contexts diverging from 50–75% of the fricative duration onward. In English, the excitation-drop trajectories showed similar effects of vowel height; however, the trajectories for high vowels diverged later than in Japanese. Peak bandwidth exhibited context effects only for Japanese /ɕ/, where it was lower in back vowel contexts across the first 75% of the fricative duration.
Acoustic and articulatory characteristics of “weak” and “strong” initial sibilants in Chamalal (Andic)
Authors: Grawunder Sven , Alieva Zaynab
Published: May 2015

In the phonological descriptions of a number of Caucasian languages appears a “weak” vs. “strong” contrast for otherwise voiceless obstruents, which was previously described as a lenis-fortis contrast, but recently attributed as geminate. Hence, we investigate field and lab data from the Gigatli dialect of Chamalal (CJI), a language belonging to the Andic branch of Avar-Andic-Tsezic group in the Nakh-Dagestanian family, spoken in Dagestan (Russian Federation). The weak-strong contrast in Chamalal involves glottalic and pulmonic fricatives at the same place of articulation. Concretely the series of central alveolar sibilant fricatives (/s/, /sː/, and /sː’/) is focused, of which all can occur in initial position. Sagittal ultrasound-articulatography of one female speaker demonstrates wide consistency in place of articulation of the tongue tip, although differences in pre-dorsal curvatures between /sː’/ and /s, sː/ are observed. The acoustic data are based on word list elicitations of six speakers (two males/four females): the ejectives show pronounced central envelope peaks and highest intensity slopes of the following vowel, but take a middle position in duration. Two distant peaks are frequently observed in the longer envelopes of “strong” /sː/. /s/ and /sː’/ differ strongest for (>2kHz) weighted COG, whereas /sː/ ranges widely in between.
Neurophysiological correlates of perceptual learning of Mandarin Chinese lexical tone categories: An event-related potential study
Authors: Shen Guannan , Froud Karen
Published: May 2015

Recent studies have shown that certain brain event-related potentials (ERPs) are sensitive to auditory perceptual categorical boundaries. This study investigates brain responses to lexical tone categorization for three groups of adult listeners: (1) native English speakers who had no exposure to Mandarin before age 17, but took advanced Mandarin courses as adults; (2) naïve English speakers; and (3) native Mandarin speakers. Two tonal continua were derived from natural speech through interpolation within two tonal contrasts (Tone 1/Tone 4; Tone 2/Tone 3). First, category boundaries were examined through classic identification and discrimination tasks. Secondly, high-density electroencephalography (EEG) was used to record brain responses while participants listened to tones in two oddball paradigms: across-category and within-category. If perception of lexical tones is categorical, cross-category deviants are expected to elicit larger ERP responses (specifically, mismatch negativity (MMN) and P300) than within-category deviants. Both behavioral and ERP results indicate that lexical tones are perceived categorically by native Chinese speakers but not by inexperienced English speakers. Although English learners of Chinese demonstrated categorical perception in behavioral tasks, their ERP response amplitudes were attenuated, and did not differ between within- and across-category conditions. Acoustic cues and characteristics of L2 phonological learning in adulthood are discussed.
Asymmetries in vowel perception: Effects of formant convergence and category “goodness”
Authors: Masapollo Matthew , Polka Linda , Ménard Lucie
Published: May 2015

The mechanisms underlying directional asymmetries in vowel perception have been the subject of considerable debate. One account—the Natural Referent Vowel (NRV) framework—suggests that asymmetries reflect a language-universal perceptual bias, such that listeners are predisposed to attend to vowels with greater formant convergence (Polka & Bohn, 2011). A second (but not mutually exclusive) account—the Native Language Magnet (NLM) theory—suggests that asymmetries reflect an experience-dependent language-specific bias favoring “good” exemplars of native language vowel categories (Kuhl, 1993). We tested the above hypotheses by investigating whether listeners, from different language backgrounds, display asymmetries influenced by formant proximity and/or language experience. Specifically, we examined monolingual English and French listeners’ performance in a within-category AX vowel discrimination task, using variants of /u/ that systematically differed in both their degree of formant proximity (between F1 and F2) and category “goodness” judgments. Results revealed asymmetries that pattern as predicted by NRV when pairs of /u/ tokens exhibited a relatively larger difference in their F1-F2 convergence patterns, and as predicted by NLM when the pairs of /u/ tokens exhibited a relatively smaller difference in their F1-F2 convergence patterns. These findings suggest that language-universal perceptual biases and specific language experience interact to shape vowel perception.
Blind separation of heart sounds
Authors: Chen Lingguang , Wu Sean F. , Xu Yong , Lyman William D. , Kapur Gaurav
Published: May 2015

This paper presents blind separation of heart sounds by de-convoluting the directly measured mixed signals using the temporal Green’s function or the point source separation (PPS) method (Wu and Zhu, JASA, 2012). The objective of this study is to examine the feasibility of using a practical and cost-effective method to separate the aortic, pulmonic, mitral and tricuspid sounds that are involved in the first and second heart sounds, respectively. It is emphasized that because many parameters such as the locations from which the heart sounds are originated, as well as the speed at which heart sounds travel inside a human body are unknown a priori, it is unrealistic to expect a perfect separation of the heart sounds. To begin with, we conduct a numerical simulation test that uses an iteration scheme to locate sources and determine the speed of sound. This is done by applying PPS algorithm repeatedly under different source locations and speeds of sound. Results show that this iteration always leads to a convergent range of source locations and speeds of sound, from which approximate values of source locations and speed of sound can be determined. Once this is completed, the signals from individual sources are separated by de-convoluting the mixed signals with respect to individual source locations. This blind source separation methodology is then applied to the heart sounds measured on volunteers to separate the aortic, pulmonic, mitral, and tricuspid sounds.
Measurements of three-dimensional acoustic propagation in a scale-model canyon
Authors: Sagers Jason D.
Published: May 2015

Scale-model acoustic propagation experiments were conducted in a laboratory tank to investigate three-dimensional (3D) propagation effects induced by range-dependent bathymetry. The model bathymetry, patterned after measured bathymetric data, represents a portion of the Hudson Canyon at 1:7500 scale and was fabricated from closed-cell polyurethane foam using a computer-numerically controlled (CNC) milling machine. In the measurement apparatus, a computer-controlled positioning system locates the receiving hydrophone at user-defined points in 3D space while the stationary source hydrophone emits broadband pulsed waveforms. Precise control of the receiving hydrophone permits the creation of synthetic arrays from which horizontal and vertical beamforming is performed. Results are shown for propagation paths along and across the axis of the canyon where the received time series are post-processed to estimate travel times, transmission loss, and horizontal and vertical arrival angles. [Work supported by ONR.]
Identifying vocal changes due to environmental changes: Real-time Lombard effect
Authors: Jensen Zachary R. , Whiting Jennifer K. , Leishman Timothy W. , Hunter Eric J.
Published: May 2015

School teachers are known to have an elevated risk of voice problems due to speaking demands in the workplace, as well as noise conditions in the classroom. Six elementary school teachers were recorded for a full school day using a neck-worn accelerometer and microphone. Classroom noise levels were also recorded using seven stationary microphones distributed randomly throughout the room. A method was developed that used the accelerometer signal to identify when a teacher is speaking, subsequently calculating a speech-to-noise ratio from six hours of teaching. Speech levels and fundamental frequencies were assessed through the accelerometer signal. The former were compared to temporally and spatially proximate noise levels from the neck-worn microphone when the teacher was not speaking. The speech data was also compared to spatially averaged and temporally proximate classroom noise levels when the teacher was not speaking. While unique in the duration of the observation for the various teachers, the speech-to-noise ratio exhibited trends related to those suggested in previous studies and is congruent with the Lombard effect. A good understanding of how a teacher compensates for realistic occupational noise conditions can lead to better recommendations for the teacher to retain good vocal health. The method and speech trends will be discussed, and future methodological improvements will be suggested.
Acuity to noise and occupational voice risks in simulated acoustical environments
Authors: Berardi Mark L. , Whiting Jennifer K. , Eyring Nathan G. , Rollins Michael K. , Jensen Zachary R. , Hunter Eric J. , Leishman Timothy W.
Published: May 2015

School teachers are known to have an elevated risk of voice problems due to the vocal demands in their work environments. Forty-five participants (20 females, 25 males, 7 elementary school teachers, and 38 college-age adults) performed a short vocal task in two different rooms: a variable-acoustics room and an anechoic chamber. The subjects were taken back and forth between the two rooms using a deception protocol. Each time they entered the variable-acoustics room, the acoustical characteristics (two background noise conditions and two reverberation conditions) had been changed without a visual appearance of change. Analysis was conducted on recorded second and third sentences of the first paragraph of the Rainbow Passage. Results revealed that differences in response to reverberation was gender specific. Additionally, school teachers seemed to be more susceptible to the noise condition.
Low-cost redesign of a music rehearsal space for high school ensembles
Authors: Murray Gabe , Burns Thomas
Published: May 2015

This presentation describes the redesign of an existing multi-purpose practice room used by high school concert bands, drumlines, and choral groups. Resource and cost restrictions limited the redesign and evaluation process for surface finishes only. The existing space had minimal early reflections and reverberation due to copious amounts of thick acoustic wall panels, resulting in a dead sound for choral and band use. The biggest challenge was to reposition the wall panels by distributing them in a checkerboard pattern, thereby balancing them with the reflective surfaces of the painted cinderblock underneath. In addition, one third of the absorptive suspended ceiling tile was replaced with 5/8” gypsum panels, and one third of the ceiling tile was removed altogether in order to couple the interstitial space above the suspended ceiling and increase the effective volume of the space. Odeon was used to create auralizations of various configurations by convolving anechoic recordings of a snare drum with the computed impulse responses, which will be demonstrated. This work was done as part of the Eagan, MN, High School Mentor Program and a professional partnership with Starkey Hearing Technologies.
The perceptual influence of the cabin acoustics on the reproduced sound of a car audio system
Authors: Kaplanis Neofytos , Bech Søren , Tervo Sakari , Pätynen Jukka , Lokki Tapio , Waterschoot Toon v. , Jensen Søren H.
Published: May 2015

A significant element of audio evaluation experiments is the availability of verbal descriptors that can accurately characterize the perceived auditory events. In terms of room acoustics, understanding the perceptual effects of the physical properties of the space would enable a better understanding of its acoustical qualities, and stipulate perceptually relevant ways to compensate for the subsequent degradations. In contrast to concert halls, perceptual evaluation of everyday-sized and less reverberant spaces has been a challenging task, and literature on the subject is limited. In this study, a sensory evaluation methodology [Lokki et al., J. Acoust. Soc. Am. 132, 3148–2161 (2012)] was employed to identify the most relevant attributes that characterize the influence of the physical properties of a car cabin on the reproduced sound field. A series of in-situ measurements of a high-end car audio system was performed for different physical settings of the car's cabin. A novel spatial auralization methodology was then used, and participants were asked to describe verbally the perceived acoustical characteristics of the stimuli. The elicited attributes were then analyzed following a previous review [Kaplanis et al., in 55th Int. Conf. Aud. Eng. Soc. (2014)] and possible links to the acoustical properties of the car cabin are discussed. [This study is a part of Marie Curie Network on Dereverberation and Reverberation of Audio, Music, and Speech. EU-FP7 under agreement ITN-GA-2012-316969.]
Multimodal communication in wolf spiders: Playback studies with visual and vibratory signals
Authors: Uetz George W. , Clark David L. , Stoffer Brent , Kozak Elizabeth C. , Lallo Madeline , Kane Heather
Published: May 2015

Previous studies of Schizocosa ocreata wolf spiders have shown that visual and vibration signals are equally capable of eliciting female receptivity, but that multimodal cues enhance female response. Studies also indicate that signals in both modes convey male quality information; females choose males with larger foreleg tufts or greater amplitude vibratory signals. Male spiders eavesdrop on both the visual and vibration signals of other males and exploit them to find mates. We examined female mate preferences and male eavesdropping using video-vibratory playback experiments. Female S. ocreata respond to playback of male courtship, showing responses to both visual and vibratory signals alone, as well as multimodal playback. Females also showed preference for male quality indicators in both sensory modes. Eavesdropping males responded to playback of male courtship with displays of their own, but responded to signal modes differently. Males displayed a higher rate of courtship tapping in response to isolated vibration signals compared to visual or multimodal stimuli. However, in choice tests, males responded with higher display rates with multimodal and visual stimuli. Results suggest that visual, vibratory and multimodal courtship signals provide information about potential mates and rivals, and that responses of males and females may differ depending on context.
Novel polymer-lipid assemblies for stimulus-responsive imaging contrast agents
Authors: Goodwin Andrew P.
Published: May 2015

Stimulus-responsive macromolecular structures are of tremendous importance for the next generation of tools for in vivo imaging and site-directed therapy. In this talk, I will present our research group’s work regarding the creation of self-assembled amphiphilic structures that respond to the presence of biomarkers that present as hallmarks for disease such as deep venous thrombosis and cancer. In one instance, the mechanical properties of synthetic, lipid-shelled microbubbles could be manipulated to sense for the biomarker thrombin using DNA hybridization. These microbubbles were found to have “on-off” ratios of ~100 and could highlight regions of elevated thrombin in real time in a live rabbit model. In another research direction, low-contrast nanoemulsions were designed to vastly increase their detection capabilities in response to chemically-induced changes in their surface properties. Both examples showcase a method for obtaining site- or biomarker-specific contrast enhancement for deep tissue imaging using commercially available technologies and have excellent promise for advancement to clinical use.
Broadband attenuation measurements of tissue-mimicking phantoms employed for histotripsy
Authors: Crowe Michael J. , Raymond Jason L. , Holland Christy K. , Bader Kenneth B.
Published: May 2015

Tissue-mimicking phantoms have previously been developed for assessing the efficacy of therapeutic ultrasound. A new modality of focused ultrasound, histotripsy, relies on the formation of shockwave-induced cavitation to ablate tissue mechanically. The objective of this study was to use a broadband ultrasound method to determine the frequency-dependent attenuation for histotripsy tissue phantoms. An agar tissue phantom was developed with evaporated milk to mimic the acoustomechanical properties of prostate tissue, a key target for histotripsy. The attenuation of this tissue phantom was measured between 2 and 20 MHz using a through-transmission technique with a single pair of PVDF transducers. The power law dependence of the acoustic attenuation spectra was linear with frequency (R2 = 0.98). The attenuation coefficient of the tissue phantom was 0.62 ± 0.02 dB/cm/MHz, which is lower than that reported for ex vivo human prostate at 5 MHz. The broadband measurements techniques utilized provide a straightforward metric for the attenuation spectrum of tissue phantoms developed for shocked insonation regimes.
Ultrasound causes stem cell differentiation even in the absence of specific biochemical growth factors
Authors: Shah Nirali , Manuelpillai Ursula , Morsi Yosry , Manasseh Richard
Published: May 2015

Experiments are presented on the effect of low-intensity ultrasound (LIUS) on stem cell differentiation. Previous studies had shown that LIUS can increase stem cell proliferation, and that LIUS in combination with biochemical growth factors (GFs) specific to particular cell lineages resulted in stem-cell differentiation into those lineages. However, studies had not been performed with LIUS alone. Amniotic-membrane-derived mesenchymal stem cells (MSCs) were subjected to continuous-wave insonation at 1 MHz and 0.015–0.072 MPa for periods of 10, 20, and 30 min daily for 15 days. Experiments were done both with a negative control (no insonation) and a positive control: a GF known to cause differentiation into smooth muscle cells (SMCs). The extent of differentiation was quantified by immunohistochemical fluorescence. Results showed that LIUS alone caused MSCs to differentiate into SMCs, with statistically significantly greater expression of SMC markers in the 10 and 20 min groups, with the 20 min group showing the highest differentiation. However, the 30 min group was negatively affected by insonation, with lower proliferation and differentiation. Since MSCs can differentiate into many cell lineages, the results imply that LIUS favors smooth muscle cells, with implications for in-vivo treatment of vascular disease and tissue engineering.
A unified equivalent circuit of electromechanical transducers
Authors: Ge Li-Feng
Published: May 2015

It has been interesting to find a unified equivalent circuit of electromechanical transducers for a long time. Hunt provided a method using a space operator to represent all transducer types with a single form of equivalent circuit [Hunt, Electroacoustics, 1954]. But, as indicated by Beranek, the space operator k does not commute with the time operator j, so that one must define jk=−kj [Beranek, JASA 77(4), 1309–1313, 1985]. During the last decades, the research on micromachined electrostatic or capacitive ultrasonic transducers stimulates further the interest in the subject [Ge, Sc. China, A 29(11), 1308–1315, 1999]. In this work, the space operator is not used. A transformation factor is defined as a ratio of blocked electrical-to-mechanical transfer impedance to blocked electrical impedance, thus, the factor is a real number for reciprocal transducers and imaginary for antireciprocal ones, which indicates the essential difference of the two types of transducers. Then, the corresponding driving-point electrical impedances are derived, and the expressions for the two are identical, demonstrating their common properties also. Thus, a unified impedance-type equivalent circuit for electromechanical transducers can be further obtained. [Work supported by NSFC (Grant Nos. 60374044 and 60774053).]
Listener preferences for vibrato rate and extent in synthesized vocal samples
Authors: Nix John P.
Published: May 2015

An experiment was devised to test the preferences of singers, vocal teachers and choral directors for vibrato rate and extent on the /a/ and /i/ vowels and with two different “gender” singers by using the voice synthesis program Madde, which is capable of varying vibrato rate, extent, fundamental frequency, and formant frequencies. The study also sought to determine if the vowel and “gender” of the singer (as determined by the formant frequencies used for the simulation) have an impact on listener preferences. Subjects answered a series of questions about their musical training and occupation, then listened to four samples each, two of the “male” voice performing the vowels at 220 Hz, and two of the “female” voice performing the same vowels at 440 Hz. The order in which the samples were presented and the initial vibrato rate and extent conditions of the simulations were varied to try to negate any order effects on the data. The investigator adjusted the vibrato rate and vibrato extent until the listener felt his or her preference was being best represented. Listeners displayed a wide variety of preferences, with those most involved in musical theater and early music performance preferring a narrower vibrato extent.
Perception of non-vibrato sung tones
Authors: Wooding Randi , Nix John P.
Published: May 2015

Singers are often asked to sing with a non-vibrato production. However, the term non-vibrato is problematic, as all human singing involves fundamental frequency variation. Whether a singer achieves a quality of tone that is perceived as non-vibrato may depend upon the experience of the listener. The specific aim of this study was to determine at what point a tone is perceived as non-vibrato by a population (N = 131) of singers, voice teachers, choir directors, and speech pathologists. Utilizing voice samples that exhibit a variety of vibrato rates and extents, the investigators sought to determine: (1) if there is a threshold for the perception of non-vibrato tone with regards to vibrato extent; (2) if given similar vibrato extent, does vibrato rate effect perceptual judgments of non-vibrato tone; (3) if there are differences in the perceptual threshold of non-vibrato tone across different professions of listeners. Participants responded to an online survey featuring randomized samples of sopranos singing [ɑ] with a variety of vibrato rates and extents. Some samples were repeated to test response reliability. Results indicate a perceptual threshold exists with regards to vibrato extent, and that vibrato rate can override the effect of a narrow or wide extent to some degree.
Effect of acoustic feedback on the singing voice
Authors: Bottalico Pasquale , Hunter Eric J. , Graetzer Simone
Published: May 2015

Voice control is of great importance in a singer’s training, and in particular, control of pitch (fundamental frequency) and volume (sound pressure level). We hypothesize that a singer’s vocal comfort and control will be increased as the acoustic feedback of the room is increased. In this study, 20 singers (10 amateur and 10 professional singers) performed vocal tasks in different acoustic conditions. Vocal tasks comprised scales and arpeggios with different dynamics at different speeds, and an extract from the American National Anthem, which was accompanied by a musical track emitted at different power levels. After each condition, the subject responded to questions regarding perception of vocal comfort, control, and fatigue, and their own voice feedback. Room acoustics were manipulated: in some conditions, two reflective panels were placed at different distances from the subject. The results indicate that when panels were present, singers tended to perceive the room as being more pleasant to sing in. Intonation (pitch control) and the Lombard Effect (a tendency to increase in voice level as background noise level increases) for singers are related to variation in the room acoustics.
Propagation model based explosive yield determination from stratospheric infrasound arrivals: Humming Roadrunner data analysis
Authors: Waxler Roger M. , Green David , Lalande Jean-Marie
Published: May 2015

Attempts to estimate explosive yields from stratospheric infrasonic returns have often relied on empirical relationships between explosive charge weight, source-to-receiver range, and a simple parameterization of the atmospheric state. We propose to approach the yield estimation problem by combining knowledge of acoustic generation by explosions and numerical acoustic propagation modeling using state-of-the-art atmospheric specifications (G2S). The goal is to provide a more accurate and robust yield estimation tool that can incorporate a variety of meteorological scenarios. We introduce an approach based on modeling the transmission loss between source and receiver using an incoherent modal sum. The total observed signal power is related to the near-field acoustic power generated by the source event. The technique is applied to stratospheric returns recorded from the Humming Roadrunner Ground Truth experiments performed in the August 2012 in the American West.
Computational modeling of distortion product otoacoustic emissions
Authors: Bowling Thomas , Che Kaikai , Lemons Charlsie , Meaud Julien
Published: May 2015

Otoacoustic emissions are sounds generated by the cochlea that can be measured in the ear canal. Distortion product otoacoustic emissions (DPOAEs) are generated when the cochlea is stimulated by two primary tones and are a result of nonlinearities within the outer hair cells of the cochlea. DPOAEs are commonly used clinically to determine the health of the inner ear and scientifically to obtain noninvasive data about cochlear function. A physiologically based computational model of the mammalian ear is used to study the generation of DPOAEs. This model includes a nonlinear model of the cochlea, formulated in the time-domain and based on the finite element method and a lumped parameter model of the middle ear. Model simulations for the basilar membrane displacement, intracochlear fluid pressure, and ear canal pressure at the distortion product frequency in response to a two-tone stimulus are compared with experimental data and other modeling studies. The effects of various primary frequencies and input signal levels on the generation of DPOAEs are studied.
Short-term adaptation in acoustical and cochlear-implant hearing
Authors: Smith Robert L. , Azadpour Mahan
Published: May 2015

Sound onset and changes in sound intensity appear to play important roles in many aspects of hearing, e.g., detection, speech communication, and source identification. Perhaps for this reason the auditory system displays mechanisms that emphasize changes in sound intensity at multiple levels of neurophysiological processing. Short-term adaptation, observed in auditory-nerve responses, is perhaps the most peripheral example of onset emphasis. It can be observed in its simplest form in the auditory-nerve response to a constant-intensity tone burst where firing rate is maximum at response onset and decays to a steady-state value during the tone. Firing rate drops below spontaneous rate following tone offset, and the response to brief probe tones is reduced and gradually recovers in this post-stimulation interval. Short-term adaptation is generally assumed to occur in auditory hair cells and cochlear-implant stimulation by-passes hair cells and hence this potential source of adaptation. The results reviewed here will describe a model of peripheral short-term adaptation and how this model can be added to cochlear-implant speech processing. Preliminary results will be presented that indicate that adding short-term adaptation to cochlear-implant processing produces an improvement in speech intelligibility on the order of 5% to 10% in a variety of listening tasks.
Intra-subject variability in frequency-following responses and cortical event-related responses to Mandarin tones
Authors: Xie Zilong , Chandrasekaran Bharath
Published: May 2015

Frequency-following responses (FFRs) reflect phase-locked responses from neuronal ensembles within the auditory brainstem and midbrain. Due to the high fidelity to stimulus characteristics, the FFRs have been extensively studied as biomarker, reflecting the integrity of subcortical encoding of complex auditory events. More recent studies suggest that the FFRs are highly malleable, and are influenced by higher-level attentive and cognitive mechanisms, as well as short-term auditory experiences. Here, we evaluate intra-subject variability of FFRs to complex speech sounds and examine relative differences in intra-subject variability between FFRs and cortical evoked responses. We elicited FFRs to two Mandarin tones (tone 1 and tone 2) from four native Mandarin speakers over five repeated daily sessions within a week. We also recorded cortical evoked responses to these two Mandarin tones presented in an oddball paradigm from these participants during these five sessions. Several measures were used to quantify FFRs: signal-to-noise ratio, stimulus-to-response correlation, and response-to-response correlation. Our analyses show that FFRs exhibited low intra-subject variability, whereas cortical responses such as N1, P2, and mismatch-negativity demonstrated higher intra-subject variability. Our findings demonstrate high individual stability in the FFRs and FFRs can be reliable biomarker to study the integrity of subcortical encoding of speech sounds.
Variability in word recognition by adults with cochlear implants: The roles of perceptual attention versus auditory sensitivity
Authors: Moberly Aaron C.
Published: May 2015

Enormous outcome variability exists for postlingually deafened adults who receive cochlear implants (CIs). This variability is not purely a result of the degradation of speech representations through implants. Data from two studies are presented that examined variability in word recognition as explained by “perceptual attention” and “auditory sensitivity” to acoustic cues underlying speech perception. In each experiment, postlingually deafened adults with CIs and normal-hearing (NH) controls performed three tasks: (1) word recognition in quiet; (2) labeling for three sets of stimuli that varied based on acoustic cues in the amplitude, duration, or spectral domains; and (3) discrimination of nonspeech analogs of these acoustic cues. Word recognition was found to vary widely among CI users (20 to 96%). Attention to spectral cues, as measured by weighting coefficients computed from labeling functions, beyond simple sensitivity to spectral cues, as measured by d′ values, predicted variability in word recognition. Attention and sensitivity to nonspectral cues did not predict variability in word recognition. Efforts should be made to better represent spectral cues through implants; however, facilitating attention to these cues through auditory training should also be a clinical focus.
Vibrational modes of a thin bar
Authors: Garrett Steven L.
Published: May 2015

Although most traditional acoustics textbooks that treat vibration (e.g., Rayleigh, Lamb, Morse, Morse and Ingard, Kinsler and Frey) address the longitudinal, torsional, and flexural modes of a thin bar, they do not stress the importance of sound speed measurements for the experimental determination of elastic moduli. This presentation will demonstrate a simple and inexpensive apparatus that uses two coils of copper wire and permanent magnets, developed by Bob Leonard and Izzy Rudnick at UCLA, that can be used to excite and detect all three modes of a free-free bar, accurately measure their modal frequencies, and use those results to provide accurate and precise values for the elastic moduli of the bar material [JASA 88(1), 210 (1990)].
Guitar pickups and the plucked string
Authors: Russell Daniel A.
Published: May 2015

This demonstration will use optical, magnetic, and piezoelectric guitar pickups to measure time signals and frequency spectra for the displacement, velocity, and force (measured at the bridge) of a plucked and struck guitar string. For the plucked string, experimental observations of the displacement and velocity of a point on the string agree very well with theory. Frequency spectra also agree well with theoretical predictions and highlight the differences in timbre between the audio signals obtained with each pickup. The demonstration will briefly discuss theoretical time signals and frequency spectra for a point on a plucked string, show measured time signals and frequency spectra from the various pickups, and compare audible examples of the sounds from the pickups for a plucked string. For the struck string, a simple theory approximates the basic shape of the string displacement and velocity, but dispersion effects in the string and the reality of the hammer-string interaction are evident in the measured string response. If time permits, a demonstration of the sound and spectrum of a compound string will be included.