bluuebunny/crossref_metadata_2025 huggingface dataset:
Damping and nonlinearity in elastic metamaterials: Treatment and effects
Authors: Khajehtourian Romik , Frazier Michael J. , Bacquet Clémence , Hussein Mahmoud I.
Published: May 2014

Locally resonant acoustic/elastic metamaterials have been the focus of extensive research efforts in recent years due to their attractive dynamical characteristics, such as the possibility of exhibiting subwavelength bandgaps. In this work, we present rigorous formulations for the treatment of damping (e.g., viscous/viscoelastic) and nonlinearity (e.g., geometric/material) in the analysis of elastic wave propagation in elastic metamaterials. In the damping case, we use a generalized form of Bloch's theorem to obtain the dispersion and dissipation factors for freely propagating elastic waves. In the nonlinear case, we combine the standard transfer matrix with an exact formulation we have recently developed for finite-strain elastic waves in a homogeneous medium to obtain the band structure of a 1D elastic metamaterial. Our analysis sheds light on the effects of damping and nonlinearity on the dispersive characteristics in the presence of local resonance.
Effects of early auditory deprivation on auditory-visual development
Authors: Houston Derek
Published: May 2014

Auditory perception does not develop in isolation. In typically developing infants, the auditory system develops integrally with other sensory and motor systems. This integrality is disrupted in deaf infants. Even those who gain access to sound through cochlear implantation undergo a period of auditory deprivation where the other sensory systems develop independently from audition before access to sound begins. In this presentation, I will report findings from several studies of infants and toddlers with cochlear implants where we have found that they perform more poorly on auditory-visual integration and association tasks (e.g., novel word learning) than normal-hearing peers. Moreover, longer periods of auditory deprivation correlate with poorer performance on auditory-visual association tasks. I will discuss the implications of these findings on sensitive period of language acquisition. I will also present preliminary results from a new study that is further exploring multi-modal integration and learning in hearing-impaired infants. We are using head-mounted cameras, eye trackers, and microphones to analyze multi-modal communicative interactions between infants with hearing loss and their parents during free play sessions. By investigating the dynamics between multi-modal input and interactive behavior, we hope to gain important insights into how impaired sensory integration affects communicative interactions and multi-modal learning.
Comparison of shallow water mode transport theory with acoustic transmissions during Shallow Water Experiment 2006
Authors: Raghukumar Kaustubha , Colosi John A. , Lin Ying-Tsong , Duda Timothy F. , Newhall Arthur , Becker Kyle M. , Hines Paul
Published: May 2014

Coupled-mode transport theory appears to have put on solid theoretical ground acoustical scattering by internal waves in both deep and shallow water, over a range of low, medium, and high frequencies [Raghukumar and Colosi (2014) and Colosi and Morozov (2009)]. Here, full-field theoretical calculations of the acoustic field moments are compared against experimental data gathered during the Shallow Water Experiment 2006. Transport theory at low frequency is validated using data gathered by the WHOI Shark array at 175 Hz with a source towed by R/V Sharp at several different speeds over distances of 1.5–5.5 km. At high frequencies, comparisons are made at 1.2 kHz using data received by a WHOI bottom-mounted single hydrophone unit with a source towed by CFAV Quest over distances of 0–20 km. Acoustic observables include the mean and variance of intensity. The effect of a range dependent stochastic internal wave field is examined in the context of data-model comparison, along with the effect of random surface waves. In addition, further insights into mode coupling are presented using the shallow water hybrid transport theory.
Behavioral analysis of lateral line and vestibular hair cell function in developing Xenopus laevis
Authors: Stevens-Smith Andrew T. , Simmons Andrea
Published: May 2014

Xenopus tadpoles are aquatic, nocturnal animals with well-developed superficial lateral line neuromasts. We previously showed that these animals, from premetamorphic through early froglet stages, exhibit stereotyped responses to low velocity flow fields—they move downstream at flow onset, and then turn and orient towards the flow source (positive rheotaxis). They continue to station hold in this oriented position for the duration of the stimulus. Positive rheotaxis and station holding are disrupted, but not totally eliminated, when animals are exposed to high concentrations of the ototoxic drug gentamicin. These data suggest that another sensory system is involved in detection of current flow. To determine the role of vestibular hair cells in these behaviors, we injected gentamicin directly into the tadpoles' otic capsules. This procedure damaged the developing otoliths and resulted in abnormal circular swimming movements and increased latency of rheotaxis and station holding. These behaviors were not, however, completely disrupted. These data suggest that the lateral line and vestibular systems act together in mediating responses of Xenopus tadpoles to flow fields.
Underwater signal attenuation of northern red-legged frog calls
Authors: Gronborg Jodi
Published: May 2014

Shallow water acoustics can dramatically alter spectral profiles of the northern red-legged frog underwater advertisement calls and should be taken into consideration when designing man-made aquatic environments as part of habitat mitigation. While much is known about atmospheric constraints on acoustic communication, we need to learn more about aquatic constraints. What is known about underwater acoustic signal transmission is garnered primarily from deep ocean research, leaving much to be discovered about the relatively extreme shallow underwater environments such as exists in ponds. The northern red-legged frog, Rana aurora, is one of three ranid species shown to vocalize while submerged underwater, and only one of two known to use the underwater portion of its environment for mating. My hydrophone recordings of the underwater chorus include calls with dominant frequencies in the 5000—15000 Hz range, sharply contrasting with the established dominant frequency range for advertisement calls of the northern red-legged frog of 450–1300 Hz. I conducted frequency sweep playbacks at breeding which demonstrate that shallow residential water bodies have unique frequency responses that dramatically alter the spectral profiles of underwater signals. This changes the frequency characteristics of what is heard by females and could significantly impact reproductive success.
In vivo ultrasonic attenuation in cetacean extracranial soft tissues
Authors: Gray Michael D. , Rogers Peter H. , Cameron Peter J. , Bossart Gregory D.
Published: May 2014

In vivo ultrasonic attenuation was estimated for extracranial soft tissues of two Tursiops truncatus and one Delphinapterus leucas. Backscatter data were non-invasively collected as part of routine health-based ultrasound examinations using a transducer operating in the 2.0–3.5 MHz frequency range. Data sets collected over the proximal mandible and temporal regions were processed to yield estimates of attenuation using a reference tissue phantom whose properties had been independently determined. The estimated attenuations were at the low end of the range of reported values for in vitro mammalian fatty and connective tissues.
Ultrasound acoustic shadow width is an accurate predictor of kidney stone size
Authors: Lee Franklin C. , Dunmire Barbrina , Harper Jonathan D. , Cunitz Bryan W. , Paun Marla , Bailey Michael , Sorensen Mathew D.
Published: May 2014

Previous studies have shown overestimation of kidney stone size in ultrasound images. We explored measuring the stone's acoustic shadow as a predictor of stone size. Forty-five calcium oxalate monohydrate (COM) kidney stones ranging from 1 to 10 mm were imaged in a water bath using a research-based ultrasound system and C5-2 transducer. Stones were imaged at depths of 6, 10, and 14 cm. The widths across the stone image and across acoustic shadow distal to the stone image were measured by the operator and through an automated algorithm. Measuring size across the stone image consistently overestimated: overestimation was 0.9±0.8 mm, 1.5±1.0 mm, 2.0±1.2 mm (manual) and 0.5±1.7 mm, 0.4±1.5 mm, 0.8±1.1 mm (automated) at 6, 10, and 14 cm depths. Measurement of the acoustic shadow width more accurately estimated stone size: 0.0±0.4 mm, 0.0±0.6 mm, and-0.2±0.8 mm (manual) and 0.2±0.5 mm, 0.1±0.8 mm, and 0.1±1.0 mm (automated) at 6, 10, and 14 cm depths. Measurement from the shadow reduced misclassification of passable stones <5 mm to requiring surgery >5 mm from 25% to 7%. The results have implications for directing treatment of asymptomatic stones based on ultrasound images. [Work supported by NIH DK043881, DK092197, and NSBRI through NASA NCC 9-58.]
Treatment planning and strategies for acousto-optic guided high-intensity focused ultrasound therapies
Authors: Adams Matthew T. , Cleveland Robin O. , Roy Ronald A.
Published: May 2014

Real-time acousto-optic (AO) sensing has been shown to non-invasively detect changes in ex vivo tissue optical properties during high-intensity focused ultrasound (HIFU) exposures. The technique is particularly appropriate for monitoring non-cavitating lesions that offer minimal acoustic contrast. This work employs a modeling-based approach to improve the AO sensing of lesion formation during HIFU therapy, to develop treatment strategies for the ablation of large volumes, and to assess the technique's viability and robustness in a clinical setting. The angular spectrum method is used to model the acoustic field from the HIFU source. Spatio-temporal temperature elevations induced by the absorption of ultrasound are modeled using a finite-difference time-domain solution to the Pennes bioheat equation. Changes in tissue optical properties are calculated using a thermal dose model, calibrated using experimental data. The diffuse optical field is modeled using an open-source GPU-accelerated Monte Carlo algorithm. The Monte Carlo algorithm is modified to account for light-sound interactions, using the acoustic field from the angular spectrum method, and to account for AO signal detection. AO signals are presented in the context of a photorefractive-crystal-based detection scheme, and are compared to signals obtained using standard optical detectors. [Work supported in part by the Whitaker International Program.]
Acceleration of acoustical emission precursors preceding failure in sheared granular material
Authors: Johnson Paul A.
Published: May 2014

Earthquake precursor observations are becoming progressively more widespread as instrumentation improves, in particular, for interplate earthquakes (e.g., Bouchon et al., Nature Geosci., 2013). One question regarding precursor behavior is whether or not they are due to a triggering cascade where one precursor triggers the next, or if they are independent events resulting from slow slip. We investigate this topic in order to characterize the physics of precursors, by applying laboratory experiments of sheared granular media in a bi-axial configuration. We sheared layers of glass beads under applied normal loads of 2–8 MPa, shearing rates of 5–10 μm/s at room temperature and humidity. We show that above ~3 MPa load, precursors are manifest by an exponential increase in time of the acoustic emission (AE), with an additional acceleration of event rate leading to the primary stick-slip failure event. The recorded AE are clearly correlated with small drops in shear stress during slow slip prior to the main stick-slip failure. Event precursors take place where the material is still modestly dilating, yet while the macroscopic frictional strength is no longer increasing. The precursors are of order 100× smaller in recorded strain amplitude than the stick-slip events. We are currently working on statistical methods to determine whether or not the precursors are triggered cascades. [Bouchon et al., Nature Geosci. 6, 299–302 (2013).]
Using nonlinear ultrasound to measure microstructural changes due to radiation damage in steel
Authors: Jacobs Laurence , Matlack Kathryn , Kim Jin-Yeon , Qu Jianmin , J. Joe Wall
Published: May 2014

The planned life extension of nuclear reactors throughout the United States and abroad will cause reactor vessel and internals materials to be exposed to more neutron irradiation than was originally intended. A nondestructive evaluation (NDE) method to monitor radiation damage would enable safe and cost-effective continued operation of nuclear reactors. Nonlinear ultrasound is an NDE technique that is sensitive to microstructural changes in metallic materials, such as dislocations, precipitates, and their combinations, which are quantified by the measurable acoustic nonlinearity parameter. Recent research has shown the sensitivity of the acoustic nonlinearity parameter to increasing neutron fluence in representative Reactor Pressure Vessel (RPV) steels. The current work considers nonlinear ultrasonic experiments conducted on similar RPV steel samples that had a combination of irradiation, annealing, re-irradiation, and/or re-annealing to a total neutron fluence of 0.5–5 x 1019 n/cm2(E > 1 MeV) at an irradiation temperature of 290°C. The acoustic nonlinearity parameter generally increased with increasing neutron fluence, and consistently decreased from the irradiated to the annealed state over different levels of neutron fluence. This comprehensive set of results illustrates the dependence of the measured acoustic nonlinearity parameter on neutron fluence, material composition, irradiation temperature, and annealing.
Thermoacoustic engines as self-powered sensors within a nuclear reactor
Authors: Garrett Steven L. , Ali Randall A. , Smith James A.
Published: May 2014

The core of a nuclear reactor is a particularly harsh environment when functioning properly. When there is an “incident,” possibly with the loss of electrical service that accompanied the earthquake and tsunami that struck the Fukushimi Daiichi reactors on 11 March 2011, the term “harsh” seems too tame. We review the development and testing of very simple standing-wave thermoacoustic engines that can be configured as nuclear fuel rods to exploit the temperature differences within that environment rather than try to shield the sensor from “harshness” [U.S. Pat. Appl. Serial No. 13/968,936 (Aug. 16, 2013)]. Those engines produce high amplitude sound that couples to the surrounding heat-transfer fluid to telemeter the information (as frequency and amplitude) to the exterior of the reactor vessel, again without requiring external electrical power. Laboratory results will demonstrate measurement of coolant temperature, identify evolved gases, and provide information about changes in porosity of solids. Thermoacoustic resonances are maintained without use of either an explicit physical hot or cold heat exchanger—a ceramic “stack” is the only required component. We suggest extensions of this approach to other processes that generate substantial temperature gradients, such as industrial crucibles for melting glasses and metals. [Work supported by the U.S. Department of Energy.]
Cochlear reflectance: Measurements and modeling
Authors: Rasetshwane Daniel , Neely Stephen T.
Published: May 2014

Cochlear reflectance (CR), the cochlear contribution to ear-canal reflectance (ECR), has theoretical advantages for cochlear modeling. Comparisons between measurements and models may lead to improved interpretation of cochlear status and provide a basis for making improvements to the models. Previous evaluation of clinical utility of CR measurements showed that CR did not predict auditory status or behavioral threshold as accurately as other otoacoustic emission measurements. Strategies for improving the quality of CR measurements were assessed in ECR measurements from 27 participants. Results indicate that the quality of CR measurements can be improved by (1) increased averaging time and (2) adjustment to the methods for extracting CR from ECR. Simulation of ECR was performed using a combination of a middle-ear model and a one-dimensional cochlear model. Simulated CR was the ECR difference between active and passive conditions of the model. The model simulation results were compared with measurements of ECR and CR in both the time and frequency domains. Minor disparities between measurements and model will provide a basis for improvements in the model. Substantial agreement between measurements and model suggest that CR is consistent with linear coherent reflection due to random impedance perturbations along the cochlear partition.
Mislateralization of sound images at dichotically presented a rippled noise signal and masker
Authors: Milekhina Olga , Supin Alexander
Published: May 2014

A mislateralization effect was observed when a target signal and a masker were presented dichotically: the target signal in one ear and the masker in the other ear. The target signal was band-filtered rippled noise with periodical interchange of ripple peaks and troughs positions. This interchange produced periodical timbre variations in the sound image. The masker was non-rippled band-filtered noise. In 100% of the trials, the image of periodical variations of timbre reflecting interchanges of the ripple peaks and troughs in the target signal was perceived (released from masking) at low ripple density and signal/masker ratios down to -35 dB. However, lateralization of the image depended on the signal/masker ratio. The image was correctly lateralized toward the ear of the target signal when the signal was of a higher level than the masker. The image was wrongly lateralized toward the ear of the masker presentation (mislateralized) when the masker was of a higher level than the signal. Implications to mechanisms of dichotic release from masking are discussed: the release is possible without the spatial-attention mechanism.
A detection theoretical framework for conceptualizing the bottom-up and top-down processes during concurrent-source segregation
Authors: Shen Yi
Published: May 2014

During a behavioral task involving the segregation of two concurrent sound sources, bottom-up and top-down processes could both influence the task performance. Therefore, the task performance alone is not assured to provide a complete description of perceptual segregation and does not allow the inference of the contributions from the bottom-up and top-down mechanisms. In the current study, a modeling framework for the perceptual segregation of concurrent harmonic complexes was proposed. The modeling framework allowed the experimenter to probe the status of the segregation, including (1) whether concurrent harmonic complexes were perceived as segregated sources, (2) which one of the segregated sources was used to perform the experimental task, and (3) whether the listener was able to correctly identify the perceived sources. In two experiments, listeners detected changes in the spectral shape of a target harmonic complex when a masker complex was simultaneously presented. By fitting the proposed model to behavioral data, the status of perceptual segregation, usually hidden from the experimenter, could be revealed. Furthermore, the proposed model was able to quantitatively predict the effects of fundamental frequency differences and target-to-masker ratio on concurrent profile analysis using a small number of interpretable parameters.
Cortical neural correlates of the binaural masking level difference (BMLD)
Authors: Gilbert Heather J. , Shackleton Trevor M. , Krumbholz Katrin , Palmer Alan R.
Published: May 2014

Single-cell responses to binaural masking level difference (BMLD) stimuli were measured in the primary auditory cortex of Urethane-anesthetised guinea pigs. Firing rate was measured as a function of the presentation level of 500 Hz S0 and STT pure tone signals in the presence of N0 and NTT maskers. The maskers were white noise, low-pass filtered at 5 kHz, with a spectrum level of 23 dB SPL. Responses were similar to those previously reported in the inferior colliculus (IC). At the lowest tone signal levels, the response was dominated by the noise masker, at higher signal levels the firing rate either increased or decreased. Signal detection theory was used to determine detection threshold. Very few neurones yielded measurable detection thresholds for all four stimulus conditions, and there was a wide range in thresholds. However, across the entire population, the lowest thresholds were consistent with human psychophysical BMLDs. Tone and noise delay functions could be used to predict the shape of the firing-rate vs. signal-level function. In summary, like in the IC, the responses were consistent with a cross-correlation model of BMLD with detection facilitated by either a decrease or increase in firing rate.
Binaural masking level difference on hearing impairments compensating by hearing aids
Authors: Ho Cheng-Yu , Young Shuenn-Tsong , Yeh Wen-Ying , Wang Zhi-Hong
Published: May 2014

Many researchers reported that the Binaural masking level differences are reduced in pathological conditions, such as sensorineural hearing loss, retro-cochlear hearing loss, central nervous system disease, and so on. In former studies revealed that the amount of BMLDs are about 2–3 dB or in minus. However, for sensorineural hearing loss, the adaptive method may be limited by the hearing thresholds of subjects. Therefore, to eliminate limitation of hearing thresholds, we delivered stimuli by a pair of sound chambers and receiving by hearing aids fitting with NAL-NL1 formula through headphones to subjects. There were eight mild to moderate sensorineural hearing loss subjects (6 females and 2 males, average 62.2 y/o, std. 9.7) participating in this study. With white noise as masker, we conducted pure tone detection thresholds for 125, 250, 500, 1000 and 2000 Hz in S0N0 and STTN0 conditions. The pilot results showed that the threshold differences (S0N0—STTN0) are 4, 6.3, 4.1, 6.9, and 6.3 dB from 125 to 2k Hz. The pilot results revealed that there are BMLDs on SNHLs with compensating by hearing aids. That is to say, this testing method may be used to rule out supra-threshold deficits from sensorineural hearing losses.
Spatial release from masking in musicians and non-musicians
Authors: Swaminathan Jayaganesh , Mason Christine R. , Streeter Timothy M. , Kidd Gerald , Patel Aniruddh D.
Published: May 2014

Recent research suggests that musically trained individuals have enhanced speech-in-noise perception, raising questions about the mechanisms underlying these effects. However, to probe the robustness of this finding and to evaluate theories about the possible mechanisms responsible for this performance advantage, it is desirable to examine speech-in-noise perception using a variety of methods. This study assessed the differences in spatial release from masking (SRM) in musicians and non-musicians. Spatially separating a speech target from interfering masker(s) generally improves target intelligibility; an effect known as spatial release from masking. A speech target was presented simultaneously with two or four speech maskers that were either colocated with the target (0° azimuth) or were symmetrically separated from the target in azimuth (±15° for two maskers; ±15° and ±30° for four maskers). Preliminary results for the two-masker condition indicated greater SRM in musicians than in non-musicians with the differences largely driven by lower target-to-masker ratios for musicians in the spatially separated condition. For the four-masker condition the SRMs observed for the musicians and non-musicians were more similar. However, large individual differences in performance were noted particularly for the non-musically trained group. Future research directions will be discussed, to explore the mechanisms behind these effects. Work supported by NIH-NIDCD and AFOSR.]
Significance of height loudspeaker positioning for perceived immersive sound field reproduction
Authors: Karampourniotis Antonios , Kim Sungyoung , Ko Doyuen , King Richard , Leonard Brett
Published: May 2014

Recently, new multichannel audio formats incorporating height loudspeakers have caught researchers' attention due to their ability to reproduce an immersive sound field. This study investigated the influence of the height loudspeaker positions and their signals on individually perceived sound quality. The authors generated nine-channel sound sources by convolving two anechoic musical pieces with nine selected room impulse responses measured in different distances and heights. In the listening test two layers of loudspeakers were used: the horizontal layer, following the standard ITU-R BS 775 five-channel loudspeaker configuration and the height layer (with elevation of 30°) with a total of twelve loudspeakers, located at ±30, ±50, ±70, ±90, ±110, and ±130 degrees. Four height signals were reproduced through eight different configurations of four height loudspeakers. Twelve listeners participated in the experiment, wherein they were asked to compare the randomly presented eight configurations and rank them based on their individually perceived sound quality. The experimental results indicate that despite the perceptual differences related to the room impulse responses, the perceived overall quality is significantly influenced by the positioning of the four height loudspeakers.
Availability of envelope interaural time-difference cues does not improve front/back localization of narrow-band high-frequency targets via head movement
Authors: Macpherson Ewan A.
Published: May 2014

Information about the front/rear location of a sound source is available in the relationship between the direction of head rotation and the direction of changes in interaural time and level differences (ITD and ILD). Our previous results show that such dynamic cues are highly effective for low-frequency stimuli, but minimally effective for narrowband high-frequency stimuli, in which, respectively, ITD and ILD cues are primarily available. In this study, we assessed the possible benefit for dynamic localization of providing more robust envelope ITD cues in high-frequency stimuli. Listeners judged the front/rear location of anechoic free-field stimuli presented over the central portion of a slow (~0.25 Hz), continual, 90-degree head oscillation. Stimuli were bursts of wideband (0.5–16 kHz), low-frequency (0.5–1 kHz), or high-frequency (6–6.5 kHz) random-phase noise or of raised-sine stimuli with exponent 2, modulation frequency 125 Hz, and bandwidth 6–6.5 kHz. Localization accuracy was high for wideband and lowpass stimuli but poor (and similar) for high-frequency noise and raised-sine stimuli, despite listeners' measured ITD JNDs for raised-sine stimuli being significantly lower than for high-frequency noise. The results suggest that neither veridical dynamic ILD nor ITD cues can overcome the erroneous spectral cue for front/back created by narrowband high-frequency stimuli.
Temporally diffusive reflections and the precedence effect
Authors: Pastore M.Torben , Blauert Jens , Braasch Jonas
Published: May 2014

In reverberant conditions, humans routinely demonstrate an ability to form the auditory event in the direction of the first wavefront and thus identify the direction of the (physical) sound source—the so-called “Precedence Effect.” Within limits, this effect even holds when the reflected sounds (the lag) contain more energy than the direct sound (the lead). Previously, we investigated the lateral extent of the Precedence Effect for specular reflections. The current research extends this inquiry by investigating the effect of temporally diffusive reflections, using the same stimuli, but convolving the lag with a 2-ms Hanning windowed Gaussian noise. The lead and lag stimuli were 200-ms Gaussian noise (500-Hz center frequency, 800-Hz bandwidth) presented dichotically with a programmable amount of temporal overlap. The lag/lead level ratio was increased in 2-dB steps, the lead/lag interval was varied from −5 to 5-ms in steps of 1-ms. Listeners indicated the lateralization of their auditory events with an acoustic pointer. The resulting temporal smearing substantially decorrelates lead and lag while keeping them essentially related. The Precedence Effect is found to be more robust to increases of the lag level for diffusive stimuli than for the previously tested sets of specular reflections.
Response shaping using a subordinate oscillator array
Authors: Sterling John A. , Vignola Joseph
Published: May 2014

Recent research has shown that arrays of small dynamic elements attached to a master structure can be tuned to significantly alter the time or frequency response of the system. Colloquially known as “fuzzy structures,” subordinate oscillators have led to applications including damping, radio frequency filtering, energy harvesting, and micro electro-mechanical system (MEMS) chemical vapor sensing. A passive machinery damping system will be designed and tested for silencing properties. The current subordinate oscillator array (SOA) design consists of a plate of sheet metal with arrays of cantilevers machined of similar but different lengths. These cantilevers will have a range of natural frequencies, which correspond to a desired frequency suppression range. When the SOA is mounted to a vibration source, it functions as an acoustic meta-material which traps and dissipates energy. This is accomplished by synchronizing the phase and frequency of the cantilevers with machinery peak amplitude frequencies. By designing cantilevers properly, the SOA acts as a mechanical broadband filter as opposed to a notch filter. The SOA will be tested primarily for vibration suppression performance but also for sensitivity to tolerance and energy storage density.
Acoustical characterization of grass-covered ground
Authors: Good Chelsea E. , Vignola Joseph F. , Glean Aldo A. , Judge John A. , Ryan Teresa J. , Sunny Jacob , Turo Diego
Published: May 2014

An investigation of acoustical properties of soil covered with live grass is presented. Measurements of normal surface impedance of such samples have been performed over a 200–2000 Hz frequency band using a vertical impedance tube. A phenomenological model is used to predict acoustic properties of the samples. In this work, the samples are considered as a three-component system: soil, grass roots, and foliage. Acoustic impedance of this composite material has components resulting from the different constituent elements. In order to differentiate the acoustic absorption contribution of each element, grass that was controlled for both water content and grass blade height was grown. The acoustic contribution of the soil was determined by performing measurements on unseeded ground with an equivalent watering protocol. Contributions of the roots and foliage were determined by making impedance measurements before and after shearing the mature foliage near the soil surface. The effect of water content in the soil was estimated by making measurements of the samples before and after oven desiccation. We show the effects of roots and foliage on acoustic absorption of grass-covered ground and the acoustic parameters of these complex media estimated using an equivalent fluid model.
Prediction and assessment of environmental vibrations from railway operations on Marmaray
Authors: Caliskan Mehmet , Alan Salih
Published: May 2014

Marmaray project involves upgrading of commuter lines on both sides of Bosphorus with an uninterrupted, modern, high-capacity commuter rail system. The line totals approximately 76 km including an immersed tunnel under Bosphorus. In this study prediction and assessment of environmental vibration levels due to railway traffic along 20-km portion between Gebze and Pendik on the Asian side are presented. Experimentally obtained existing soil-structure coupling and structural amplification factors for the whole line are applied to the theoretically calculated vibration levels for use in assessment studies. Vibration mitigation measures are devised with respect to Turkish Environmental Noise Regulation and criteria by the Federal Transit Administration.
Temporal characteristics of vowel articulation: Electromyographic investigation of the “articulatory period”
Authors: LaCross Amy , Bailey E.Fiona
Published: May 2014

In speech, articulator movement precedes the acoustic signal [e.g., Meyer (1991); Gracco (1988); Lubker and Gay (1982); Bell-Berti and Harris (1981)]. The onset and offset of movement, i.e., the ‘articulatory period' (Bell-Berti and Harris, 1981, p. 13) is said to encompass the acoustic signal however the precise timing and variability of this period are not well understood. Using electromyography (EMG), we examine the onset/offset of the articulatory period as a function of phonetic context. We recorded EMG activity from the posterior and anterior regions of the genioglossus (GG) muscle of the tongue in subjects during the articulation of static vowels, static vowels with initial coronal or palatal fricatives and vowels embedded in the nonce word [∫pVp]. We show front and high vowels entail earlier onset of GG activation and that vowels preceded by coronal fricatives are associated with significantly earlier muscle activation than vowels preceded by palatal fricatives. We also note timing differences between GG regions. Thus, for these stimuli, posterior GG EMG activation encompasses the duration of anterior GG EMG activation. These findings underscore the dynamic nature of lingual movement wherein regional tongue muscle activities exhibit predictable differences determined in large part by phonetic context.
On transition between voice registers: Data from high-speed laryngeal videoendoscopy
Authors: Chen Gang , Park Soo-Jin , Kreiman Jody , Alwan Abeer
Published: May 2014

How specific aspects of vocal fold vibration alter voice register has long been a subject of interest. Transitions between vocal registers are often studied using dynamic vocal fold models and electroglottographic signals. Although laryngeal high-speed videoendoscopy has also been applied to study steady-state voice registers, there has been little such investigation on the transitions between registers. In this study, we examined voice register transitions using phonations in which vocal qualities varied continuously in fundamental frequency (F0), loudness, or voice quality (from breathy to pressed). Glottal area measures {open quotient and alternating-current to open quotient ratios [Chen et al., JASA 133, 1656–1666 (2013)]} and acoustic measures (F0, energy, and H1-H2) were studied using simultaneously collected laryngeal high-speed videoendoscopy and audio recordings from 15 subjects. The video recordings were collected transorally at 10 000 frames per second. Glottal area waveforms were extracted using GlotAnTools (Version 5) [Erlangen, Germany], and acoustic measures were gathered using VoiceSauce software and analysis-by-synthesis. Glottal area measures were compared to acoustic measures and their relationships to voice register transitions were explored.
Duration and rise-span on rising pitch in conversational American English: Rises are never both long and large
Authors: Tyler Joseph
Published: May 2014

Studies on variation in rising pitch in dialects of English have analyzed correlations of rise-start pitch, rise-end pitch, rise-span, rise-onset position (early vs. late) and pitch dynamism for how they correlate with contextual factors like speaker gender, utterance type (question vs. statement), and turn position (turn-medial vs. turn-final) [e.g., Fletcher and Harrington (2001); Ritchart and Arvaniti (2013); Warren (2005)]. Using data from the Santa Barbara Corpus of Spoken American English, this study adds the novel measure of rise duration. Modeling the data with a linear mixed model with random effects for speaker and conversation (using the lmer function in R), neither gender, utterance type, nor turn position predict rise duration. Nevertheless, rise duration does pattern with the size of the rise (rise-span): many rises are both short and small, some are short and large or long and small, but none are long and large. This suggests a phonetic restriction on the distribution of rises, with speakers avoiding the simultaneous extremes of both duration and span. With the same model testing gender, utterance type and turn position as predictors of rise-span, results show women produce larger rises on questions than statements, while men's rises show no difference between questions and statements.
The implementation of voicing in obstruents in American English connected speech
Authors: Davidson Lisa
Published: May 2014

Descriptions of obstruent voicing in English phonetics textbooks observe that [ + voice] obstruents are likely only fully voiced between other voiced sounds, but have less voicing in word-initial and word-final position [e.g., Cruttenden (2008); Docherty (1992) for experimental data for British English]. This study examines these claims for American English using a corpus of 27 speakers reading 3–5 short stories. Voiced stops and fricatives were coded for preceding and following segments, stress of the previous and following syllables, position within the word (initial, medial, and final), and phrasal position of the word. The calculation of unvoiced frames from the Praat voice report was used to obtain the proportion of voicing during each obstruent closure. Results indicate the influence of several phonotactic and prosodic factors. (1) The segment preceding the obstruent influences the amount of voicing more than the following segment does; complete devoicing and shorter durations of partial voicing are most often conditioned by preceding pauses or voiceless sounds. (2) Among following sounds, nasals condition the most complete voicing. (3) An obstruent's position within a word has less effect than its phrasal position. (3) Stress primarily affects stops: a preceding stressed syllable conditions significantly more voicing than a preceding unstressed syllable.
Phonetic accommodation in Russian-Estonian bilingual speech
Authors: Rule Cameron
Published: May 2014

The influence of L1 phonological knowledge on L2 bilingual speech has long been a fruitful topic of speech perception and production research (Piske et al., J. Phonetics 29, 191–215). Recent research examining phonetic accommodation in bilingual speech has demonstrated that L1 and L2 phonologies interact in a bidirectional, dynamic manner (Fowler et al., J. Phonetics 36, 649–663). My study builds on these results by examining the acoustic outcomes of phonetic accommodation in vowels produced by bilingual Russian(L1)-Estonian(L2) speakers. Specifically, I aim to test the hypotheses that L2 knowledge can significantly affect robust aspects of L1 speech, i.e., vowel quality, and that there is a correlation between the extent of L2 exposure and the degree of phonetic accommodation. The preliminary results of acoustic analysis suggest that bilingual speakers produce L1 vowels with formant values that are intermediate from both L1 and L2 monolingual controls, indicating that L2 exposure influences significant aspects of L1 speech. Presently, I am conducting analyses which compare individual speaker differences in the extent of phonetic convergence to the amount of their L2 use and exposure. My overarching objective is to present novel empirical evidence that expands our current understanding of phonetic accommodation in bilingual speech production.
Intelligibility in dysphonic speech: Landmark-based measures
Authors: Boyce Suzanne , Ishikawa Keiko , Speights Marisha
Published: May 2014

Speakers with voice disorders frequently report reduced intelligibility in ordinary communication situations. This effect is typically attributed to reduced loudness; however, other source/vocal tract interactions may be at work. The acoustic landmark theory of speech perception postulates that specific acoustic events, called “landmarks,” contain particularly salient information about acoustic cues used by listeners. The current study examined acoustic profiles of dysphonic speech with the publically available landmark-based automatic speech analysis software, SpeechMark™. In this study, we focused on burst landmarks, which aim to identify onsets and offsets of affricate/stop bursts. The study tested two hypotheses: (1) normal and dysphonic speech samples differ in the number of burst landmarks because laryngeal pathology affects the consistency of airflow control, and (2) the number of burst landmarks will correlate with cepstral peak prominence values, which have been shown to correlate well with perceptual judgment of dysphonia severity. Speech samples of 36 normal and 33 dysphonic speakers from KAY Elemetrics database of Disordered Voice were subjected to the analysis. Results will be discussed in the context of clinical assessment of intelligibility for dysphonic voices.
The merged vowel of PIN and PEN as realized in Bakersfield, California
Authors: Warren Ron , Fulop Sean A.
Published: May 2014

One consistently identified quality of Southern American English (SAE) is the PIN/PEN merger, wherein the vowels /ɪ/ and /ɛ/ become indistinguishable in nasalized contexts. Existing studies have shown that the merged vowel may either occupy a space between the vowel spaces of /ɪ/ and /ɛ/ [Bigham, MA thesis, UT Austin (2005)], or merge completely into /ɪ/[Koops et al., “The effect of perceived speaker age on the perception of PIN and PEN vowels in Houston, Texas,” U Penn Working Pap. Linguist. 14(2) (2008)]. Due to the dustbowl migration, areas of the southern central valley of California have a complete PIN/PEN merger similar to SAE. This study examines the acoustic properties of the merged vowel spoken by eight speakers from Bakersfield, California, ages 25 through 65. Findings indicate that the merged vowel does not occupy a compromise position, nor a merged /ɪ/ position in any but the oldest subject. Instead, the merged vowel presents significantly lower first formant values than /ɪ/, suggesting that as the California vowel shift has lowered the front lax vowels, this merged allophone has remained stationary. Further, the youngest female subjects presented an inconsistent vowel merger, suggesting a potential demerger of the type documented in southern urban centers. This raises questions about the nature of the alleged merger, if perceptible acoustic differences remain which allow for demerger.
Realization of stress in theatrical speech: The example of Composed Theater
Authors: Dimos Kostis , Dick Leopold , Dellwo Volker
Published: May 2014

In this study, we investigated syllabic stress in theatrical speech containing emphatically stressed vowels. Typical acoustic correlates of stress are intensity, pitch, and duration. The aim of this experiment was to measure whether artistic emphatic stress is realized differently in terms of these correlates compared to stress in normal speech. In an experiment, one professional performer of Composed Theater, an avant-garde type of experimental theater, was recorded both in natural and theatrical French speech. The results showed an increase in mean intensity, pitch, and mean duration in highly stressed vowels. The difference between stressed and unstressed syllables was higher in theatrical, than in normal speech. We argue that duration, pitch and intensity were used to different degrees to indicate stress in the artistic speech sample. Our study provided a preliminary comparison of speech characteristics between artistic and normal speech focusing on stress realization techniques in artistic speech performance. Additional professional speakers' recordings are currently being analyzed in terms of prosodic characteristics in avant-garde theater performance.
Assessing the effects of cognitive decline on the speech rate of demented and healthy elderly speakers
Authors: Heffinger Maria , DAmico Gina , Carozza Linda , Bell-Berti Fredericka , Krieger Pamela C.
Published: May 2014

According to current research, both age and cognitive decline have an effect on speech rate. While healthy elderly speakers are reported to speak at a slower rate than their younger counterparts, it has also been noted that elderly patients with a cognitive decline speak more slowly than their healthy elderly peers. This study analyzes the speech rates of healthy elderly speakers and compares the results with our previously reported data from speakers diagnosed with dementia. Our healthy elderly participants repeated five-syllable carrier phrases with varying target words. The durations of consonant and vowel segments will be measured using digital spectrograms to determine the extent of final lengthening, compensatory shortening, and overall speech rate (in syllables and second). Results for the two speaker groups will be compared with each other and also with results previously reported in the literature.
Temporal alignment between head gesture and prosodic prominence in naturally occurring conversation: An electromagnetic articulometry study
Authors: Goldenberg Dolly , Tiede Mark , Honorof Douglas N. , Mooshammer Christine
Published: May 2014

Studies of the relationship between speech events and gesticulation have suggested that the peak of the prosodic pitch accent serves as a target with which body gestures may be coordinated (Roth, 2002; Loehr, 2004). While previous work has relied on controlled speech elicitation generally restricted to nonrepresentational extension/retraction (Leonard and Cummins, 2011) or iconic (Kelly et al., 2008) gestures, here we examine the kinematics of the speech articulators and associated head movements from pairs of individuals engaged in spontaneous conversation. Age and gender matched native speakers of American English seated 2 m apart were recorded using two electromagnetic articulometer (EMA) devices (Tiede and Mooshammer, 2013). Head movements were characterized by the centroid of reference sensors placed on the left and right mastoid processes and the upper incisors. Pitch accents were coded following the ToBI implementation of Pierrehumbert's intonational framework following Beckman and Elam (1997). Preliminary findings show that the apex (point of maximum excursion) of head movements within an IP in general precedes the peak of the associated pitch accent, and is consistently aligned with co-occurring articulatory events within the syllable. [Work supported by NIH NIDCD-DC-012350.]
Phonation and tone in conversational Beijing Mandarin
Authors: Callier Patrick R.
Published: May 2014

Previous acoustic analyses of phonation in Beijing Mandarin and closely related varieties have shown that phonatory variability in Mandarin is conditioned by lexical tone and prosody. Tone 3 (low) and tone 4 (high fall), as-well as syllables in domain-final position, have been reported to have more negative spectral tilt (particularly lower H1-H2), indicating creaky phonation. This study examines phonation in a corpus of 6752 vowels from conversational interview speech with 16 university students in the Beijing area, using four measures of spectral tilt: H1-H2, H1-A1, H1-A2, and H1-A3. The results, which diverge from findings based on laboratory speech, are possibly the first to report on spectral tilt for tone 5 (neutral tone). In mixed-effects regression models, tone 2 (high rising) has lower H1-A1, tone 3 and tone 4 have lower H1-A1 and H1-A2, and tone 5 has lower values of H1-H2 and H1-A1. Prosodic position interacts with tone. IP-final syllables for each tone exhibit higher spectral tilt on some measures than non-final syllables, though main effects for prosodic position give lower values in IP-final position for H1-A1, H1-A2, and H1-A3. These results encourage more attention to the interaction of prosodic and tonal factors in naturalistic speaking contexts when studying phonation.