bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterizing biological scatter before, during, and after a temporary ice retreat in the Bering Sea.
Authors: Miksis-Olds Jennifer L. , Warren Joseph D.
Published: July 2011

A three-frequency echosounder system was integrated into a NOAA oceanographic mooring in the central Bering Sea from 2008–2009. Diel vertical migration patterns were examined before, during, and after the formation and retreat of seasonal ice. Scattering aggregations identified in the year long time series were classified based on the differences in scattering amplitude between the three frequencies. Theoretical scattering curves for four different types of individual scatterers were generated and decibel-differences at the three acoustic frequencies used in this study were calculated for copepods with lengths of 1 and 8 mm, euphausiids with lengths of 15 and 30 mm, and organisms with a gas-inclusion such as a swim-bladdered fish or siphonophore. Aggregations were classified into one of the four categories by determining the shortest geometric distance between the 3 dB differences calculated for the aggregation and that of the theoretical scatterers. If the closest geometric distance exceeded 16 dB, the aggregation was classified as unknown. Results indicate that the vertical movement patterns and community structure of biological scatter during a 2 week temporary ice retreat more closely resemble that of the spring bloom than the period immediately prior to the seasonal ice presence. [Work supported by the ONR.]
Challenges of clinical high intensity focused ultrasound: The need for metrology.
Authors: Hwang Joo Ha , Khokhlova Vera A. , Bailey Michael R.
Published: July 2011

Metrology of high intensity focused ultrasound (HIFU) is critical to the advancement of clinical application of HIFU for safe and effective treatments in patients. Several methods for performing metrology of HIFU systems are available in the research laboratory setting; however, translation of these methods to the clinical setting remains in evolution. From our initial experience with clinical HIFU systems we have realized the importance of accurate acoustic characterization of HIFU systems in order to determine the parameters of the treatment protocol to result in safe and effective treatments. The acoustic parameters of the system, particularly at very high intensities, are very important to understand prior to delivering HIFU therapy to patients. Improved methods of HIFU metrology, especially to determine in situ exposure and dose, will result in a more rational approach to clinical HIFU therapy. Further advances in clinical HIFU therapy will require close cooperation between clinicians and scientists in order to make HIFU therapy safe and effective. Educating clinicians on the importance of metrology will also be important. [Work supported by NIH Grant No. EB007643.]
Evolution of metrology techniques for high intensity ultrasound.
Authors: Schafer Mark E.
Published: July 2011

High intensity ultrasound device characterization presents a number of formidable measurement challenges. Whether the system is based on a high pressure, short temporal (i.e., shock wave), or a medium pressure, long temporal (i.e., HIFU) approach, the critical issue has been the destructive effects on the measurement sensor. Some shock wave systems have the additional issue of high shock to shock variability. This presentation reviews the evolution of the measurement and regulatory approaches used for characterizing high intensity devices. Every approach involves a compromise between the desire for a complete characterization of all possible parameters and the practical realities of making the measurements. Early work was done with very rugged sensors which provided nearly worthless data. The need for improved temporal and spatial resolution drove the development of a number of novel approaches including piezoelectric, force balance, and optical systems. Customized equipment has been developed for each particular type of HIU device. In some cases, measurements at low settings are used to predict results at higher settings. Improvements in measurement technology have often resulted in improved equipment designs, leading to better treatment efficacy and patient safety. However, there is still a gap between initial system characterization and day-to-day quality assurance needs.
Holographic reconstruction of therapeutic ultrasound sources.
Authors: Kreider Wayne , Sapozhnikov Oleg A. , Bailey Michael R. , Kaczkowski Peter J. , Khokhlova Vera A.
Published: July 2011

Clinical therapeutic ultrasound systems rely on the delivery of known acoustic pressures to treatment sites. Assessing the safety and efficacy of these systems relies upon characterization of ultrasound sources in order to determine the acoustic fields they produce and to understand performance changes over time. While direct hydrophone measurements of intense acoustic fields are possible, data acquisition throughout a treatment volume can be time-consuming and is only applicable to the specific source conditions tested. Moreover, measuring intense acoustic fields poses challenges for the hydrophone. An alternate approach combines low-amplitude pressure measurements with modeling of the nonlinear pressure field at various transducer power levels. In this work, low-intensity measurements were acquired for several therapeutic transducers. Pressure amplitude and phase were measured on a plane near the test transducer; the Rayleigh integral was used to back-propagate the acoustic field and mathematically reconstruct relative vibrations of the transducer surface. Such holographic reconstructions identified the vibratory characteristics of different types of transducers, including a 256-element clinical array. These reconstructions can be used to define boundary conditions for modeling and to record characteristics of transducer performance. [Work supported by NIH EB007643, NSBRI through NASA NCC 9-58, and RFBR].
Techniques for performing quantitative measurements of high intensity focused ultrasound intensity distributions noninvasively.
Authors: Hariharan Prasanna , Giridhar Dushyanth , Robinson Ronald A. , Myers Matthew R.
Published: July 2011

Estimation of the HIFU intensity field at clinically relevant power levels can be difficult due to the possibility of hydrophone damage or of sensor interference with the focused beam. To address this issue, we have developed two non-invasive methods for determining the intensity in free field and in tissue-mimicking material. In the first method, streaming field generated by the absorption of acoustic energy in liquid is measured using particle image velocimetry. The intensity distribution giving rise to the velocity field is computed by performing the operations of the Navier–Stokes equations upon the experimentally measured streaming field. The second technique (IR thermography) involves the use of an infrared camera to measure the temperature within a tissue-phantom. An air interface is required at the phantom boundary in order for the IR camera to observe the temperature rise. Quantitative determination of the intensity can be difficult due to the presence of the air interface (at which the intensity is zero), heat conduction within the phantom, and convection currents arising in the air. Mathematical relations that address these complications and allow for intensity measurements have been derived. Intensity fields obtained using both methods will be shown, along with comparisons with hydrophone measurements.
Traffic and construction noise changes in communities next to highways.
Authors: Musso Escude Laura
Published: July 2011

Residents located next to an existing highway are getting notified that their road is getting either wider or fixed such as paving or installing a traffic signal. This paper summarizes the most frequent questions asked by residents located to nearby highways where construction will occur. Some of the questions that will be addressed will be as follows: Are we getting a wall, is the noise environment will change permanently or for few month or weeks, my routines are going to change, etc. A summary of the protocol on how the state addresses long term noise impacts and temporary ones is given. It will provide an overview on what happens when a noise study is warrant and what happens after if you have mitigation such as a wall. With regard to the temporary noise impacts, the paper will include the protocol on how the agency addresses the process before and during construction.
A k-space method for nonlinear wave propagation.
Authors: Jing Yun , Clement Greg
Published: July 2011

A k-space method for nonlinear wave propagation in absorptive media is presented. The Westervelt equation is first transferred into k-space via Fourier transformation and is solved by a wave-vector time-domain scheme. The present approach is not limited to forward propagation or parabolic approximation. One- and 2-D problems are investigated to verify the method by comparing results to the finite element method. It is found that, in order to obtain accurate results in homogeneous media (errors of the fundamental and first two harmonics being less than 0.5 dB), the grid size can be as little as two points per wavelength, and for a moderately nonlinear problem, the Courant–Friedrichs–Lewy number can be as small as 0.4. As a result, the k-space method for nonlinear wave propagation is shown here to be computationally more efficient than the conventional finite element method or finite-difference time-domain method for the conditions studied here. However, although the present method is highly accurate for weakly inhomogeneous media, it is found to be less accurate for strongly inhomogeneous media.
Faraday waves produced by periodic substrates: Mimicking the alligator water dance.
Authors: Moriarty Peter , Holt R. Glynn
Published: July 2011

Male alligators use surface waves to attract their mates. This phenomenon is colloquially known as the alligator’s water dance. Male alligators vibrate their lungs at very low frequencies, creating unique wavy patterns and fountains on the surface of the water. We hypothesize that the water dance phenomena are an expression of Faraday waves, arising from the instability of the plane fluid interface to wavy perturbations above a threshold vibration amplitude. We performed laboratory experiments to study how the corrugations covering the skin of an alligator affect the onset, efficiency, and pattern of Faraday waves. A three-dimensional (3-D) printed plate was modeled after a molding of an alligator’s back, mimicking the corrugation size, shape, and spacing. An electromagnetic induction transducer was used to vibrate this model plate normal to the water surface. Frequency sweep data were collected for a variety of amplitude settings. Sweeps were performed for different plate depths, with and without corrugations. Three diagnostics were employed: a piezoelectric hydrophone, an out-of-plane laser vibrometer, and a high-speed video. Onset, frequency, and pattern data will be presented as a function of driving parameters, and as a function of depth. Implications of this work for an eventual field experiment will be discussed.
Modeling thunder propagation and detectability on Titan.
Authors: Achi Peter , Petculescu Andi
Published: July 2011

This research is part of a study investigating the characteristics of thunder on Saturn’s largest moon, Titan. In tandem with electromagnetic signatures, thunder can corroborate and quantify lightning discharges. A physical model for the propagation of thunder on Titan, based on the most recent data collected by the Cassini–Huygens mission, is being developed. The model approximates a tortuous 20 km cloud-to-ground lightning channel by an angle-wise random walk of small discharge segments, each generating a strong cylindrical shock wave, which acquires an N-wave shape after it travels through the relaxation radius, into the acoustic regime. These acoustic waves are then propagated to the far-field detector where they are added linearly to form long-range thunder. The detectability of thunder signatures by a sensor in Titan’s lower atmosphere depends on the moon’s atmospheric structure. In order to constrain the fraction of acoustic energy reaching a detector in Titan’s troposphere, the model accounts for the upward-refracting sound speed profile up to the inversion point at ∼45 km and also for ground effects. The sound speed and attenuation are computed along the length of the lightning channel (20 km) using altitude-dependent pressure, density, and temperature measurements by Cassini–Huygens, as well as thermophysical parameters (specific heats, viscosity, thermal conductivity, and diffusivity) extracted from NIST’s Chemistry WebBook.
Gasdynamic modeling of strong shock wave generation from lightning in Titan’s troposphere.
Authors: Hill Christopher S. , Petculescu Andi
Published: July 2011

In an effort to predict the characteristics of thunder on Titan, a model is being developed for the formation of the initial strong shock wave by a short cylindrical lightning discharge “segment.” (Such small discharge segments are later used to synthesize a tortuous cloud-to-ground 20 Km-long lightning channel in Titan’s troposphere.) The shock wave is obtained numerically as a solution of the coupled gasdynamic equations of state and conservation of momentum, mass, and energy. The relevant acoustic quantities are the pressure, density, particle velocity, and specific internal energy of the shock wave immediately following the discharge. Different scenarios for the initial deposition of energy from the discharge into the shock wave are investigated. The altitude-dependent ambient conditions in Titan’s lower atmosphere—temperature, pressure, and density—are extracted from Cassini-Huygens data, while specific heats and transport coefficients of the main constituents of Titan’s troposphere (N2, CH4) are obtained from the NIST Chemistry WebBook and interpolated at each altitude. The CH4 molar fraction, measured by the mass spectrometer onboard Huygens, varies from 0.0492 at 5 m to 0.0162 at 35 km (the latter marking the lower end of Titan’s tropopause). These parameters are used as inputs to the model for a complete thermodynamic characterization along the length of the lightning channel. [The work was funded by the Louisiana Space Consortium (LaSpace) and NASA.]
Modeling of photoacoustic Raman spectroscopy.
Authors: Chambers David H. , Carter J. Chance
Published: July 2011

Photoacoustic Raman spectroscopy (PARS) is a technique used to identify chemical species mixed in a gas or liquid based on their pattern of vibrational energy levels. Raman spectroscopy differs from the more familiar absorption spectroscopy by using a nonlinear two-photon process that can be more sensitive to small differences in vibrational energy levels. Thus, it can detect defect sites in solid-state optical materials or low concentrations of chemical species in gases. The Raman scattering process generates acoustic pulses that can be detected with a microphone. In this talk, we present an overview of PARS and present a model of the production of these acoustic pulses from the energy deposited in the medium during the Raman scattering process. We will discuss the different types of PARS (cw, pulsed, and resonant) and their relative advantages. Finally, we describe an experimental platform that we plan to use for validating the model. [This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.]
Individual and age related differences of normal auditory development in older (6–12 years old) children.
Authors: Moore David
Published: July 2011

The ascending, sub-cortical auditory system is anatomically and physiologically mature by 2–3 years of age, but immature hearing has been found in children up to at least 10 years. This immaturity typically takes the form of elevated detection and discrimination thresholds, and increased listener variability. But individual differences indicate adult-like performance in some younger children, suggesting that the sensory mechanisms for hearing are established relatively early. This and high response variability in other children also suggest that higher-level, cognitive aspects of hearing may be responsible for later immaturity. These predictions were examined in studies showing that standardized measures of cognition (non-verbal IQ, working memory, language, and literacy), parental reports of communication, and speech-in-noise perception all relate significantly to response threshold and variability on single tests of temporal (backward masking, 1 kHz frequency discrimination) and spectral [notch noise masking (NNM)] hearing. However, when the sensory and cognitive contributions to those measures were partially dissociated by comparing performance on paired tests (e.g., simultaneous masking and NNM), most or all poor performance appeared due to the cognitive demands of the test. These findings indicate that the later functional maturation of hearing in older children is due to cognitive rather than sensory development.
Developmental effects in susceptibility to remote-frequency masking.
Authors: Leibold Lori J.
Published: July 2011

Although the peripheral auditory system accurately encodes the fine acoustic characteristics of sound by about 6 months of age, infants and children are more susceptible to auditory masking than adults under many conditions. In particular, large developmental effects have been observed in the presence of maskers remote in frequency from the target signal. Here, we review results of behavioral investigations of remote-frequency masking across infancy and childhood. Consistent findings have been observed across studies, suggesting that the sources of age-related changes in susceptibility to remote-frequency masking are related to the maturation of perceptual auditory skills such as sound source segregation and selective attention.
Deaf infants' attention to speech after cochlear implantation.
Authors: Houston Derek M.
Published: July 2011

[Cochlear implants can provide deaf infants access to auditory information and the opportunity to learn spoken language. However, providing infants with access to auditory information does not guarantee that they will actively attend to speech. Attending to speech may be important for early language development. Recent work with normal hearing infants suggests that infants attend to speech more than a similarly complex nonspeech signal at a very young age [Vouloumanos Werker (2004); (2007)], and recent models of infant speech perception propose that early attention to speech is crucial for speech perception development [Werker Curtin (2005)]. I will present work investigating deaf infants’ attention to speech after cochlear implantation. We found that deaf infants’ attention to speech, on average, increases during the first 6 months after cochlear implantation and that there is a high degree of variability in attention to speech among infants with cochlear implants. We also found that attention to speech 6 months after implantation predicted speech perception performance 2 and 4 years later. Taken together, these findings provide evidence that attention to speech is important for speech perception development and that attending to speech may be challenging for children who experience auditory deprivation during infancy.
Vibroacoustics response of sandwich-composite panels with attached noise control materials.
Authors: Atalla Noureddine
Published: July 2011

This paper discusses the modeling of the vibration and acoustic responses of sandwich composite panels with attached sound packages, using both analytical and numerical methods. Special attention is devoted to the modeling using the transfer matrix method of these structures in various mounting conditions (single wall and double wall) together with the calculation of various vibroacoustics indicators (vibration response, radiated power, transmission loss, added damping, air-borne insertion loss, structure-borne insertion loss, etc.) under various excitations (acoustical, mechanical, and turbulent boundary layers). Examples are presented to compare the performance of the presented models and demonstrate their range of applicability and usefulness.
Acoustic analysis of honeycomb sandwich structures with perforated septa and membrane-type acoustic metamaterials.
Authors: Naify Christina J. , Chang Chia-Ming , McKnight Geoffery , Nutt Steven
Published: July 2011

Composite structures, which are commonly used in aerospace applications due to their high strength and low weight, tend to exhibit poor acoustic properties. Sandwich structures are constructed of a low-density core adhered to two thin stiff facesheets. One common assembly for sandwich panels is a divided honeycomb core made of either para-aramid paper or aluminum with fiber-reinforced composite facesheets. Typical acoustic treatments for composite sandwich structures have included the addition of foams and fibers to either the exterior of the structure or inside the core. In addition, a currently implemented treatment involves the insertion of perforated septa to the midplane of the honeycomb core, though this method’s effectiveness has not been established. Membrane-type acoustic metamaterials have been shown to increase transmission loss (TL) by up to 500% over the acoustic mass law, with multiple TL peaks achieved in a multi-celled array. In this study, experimentally obtained TL behavior of a sandwich panel with a perforated mid-core septa is compared to a panel with a mid-core layer made of the membrane-type metamaterial. FEA generated predictions were used to validate the experimental data.
Cell size effects on material properties of foam-filled honeycomb sandwich structures using finite element analysis.
Authors: Li Zhuang
Published: July 2011

In recent years, sandwich structures have become used increasingly in many applications, especially in transportation vehicles, due to their high strength-to-weight ratio, excellent thermal insulation, and good performance as water and vapor barriers. The great advantage of sandwich structures is that optimal designs can be obtained for different applications by choosing different materials and geometric configurations of the face sheets and cores. In previous research work, the foam-filled honeycomb cores demonstrate higher stiffness and vibration damping than pure honeycomb and pure foam cores. However, other properties of the foam-filled honeycomb cores have not been investigated thoroughly. In this paper, the effects of honeycomb cell size on both Young’s modulus and the shear modulus of the foam-filled honeycomb core were analyzed using finite element models developed in ANSYS. The polyurethane foam may produce a negative Poisson’s ratio by the use of a special microstructure design. The influence of Poisson’s ratio on the material properties is also presented.
An effect of phoneme frequency on stop place perception by English-speaking and Japanese-speaking listeners.
Authors: Yoneyama Kiyoko , Johnson Keith , Kataoka Reiko
Published: July 2011

The effects of phoneme frequency on stop place perception were examined. In English, [t] is more frequently observed than [k] while the opposite is true in Japanese. If the sound frequency affects the phoneme perception, English listeners would identify more of the ambiguous [t]-[k] stimuli as “t” than do Japanese listeners. In this study, a 4IAX discrimination experiment and a phoneme boundary decision experiment were conducted with English-speaking and Japanese-speaking listeners to test this hypothesis. The stimuli of the two experiments were created by the Klatt synthesizer. [ta], [ka], [to], and [ko] were recorded by a native Japanese speaker and a native English speaker, respectively. Then, [ta], [ka], [to], and [ko] were synthesized based on the parameter values obtained from the measurements of the recorded tokens. They were used as the end-point tokens of a nine-step continuum. The rest of the tokens were created by manipulating frequency parameters of the synthesizer. Four sets of [k]-[t] continua were created (two languages: English and Japanese, and two vowel conditions: [a] and [o]). A preliminary analysis of a subset of data demonstrated that the more frequent sound in each language occupied a larger perceptual region of the [a] vowel continua.
Preattentive language effects in bilinguals.
Authors: Garcia-Sierra Adrian , Silva-Pereyra Juan F. , Ramirez-Esparza Nairan , Siard Jennifer , Champlin Craig A.
Published: July 2011

Event related potentials (ERPs) were recorded from Spanish-English bilinguals (N=11) to test if their pre-attentive speech discrimination changes depending on the language they are using at the moment. ERPs were recorded in two language contexts (i.e., participants silently read magazines in the language of interest). Two speech contrast conditions were recorded in each language context. In the unique to English condition, the speech sounds represented two different sounds for the English language, but represented the same sound for the Spanish language. In the unique to Spanish condition, the speech sounds represented two different sounds for the Spanish language, but represented the same sounds for the English language. We expected that bilinguals in the unique to English condition would pre-attentively discriminate the sound during the English language context, but not during the Spanish language context. The opposite was expected for the unique to Spanish condition. A monolingual control group (N=9) was recruited to test the validity of the speech sounds tested. According to our expectations, language contexts produced an effect in the amplitude of the mismatch negativity ERP component elicited by the deviant stimulus. The results suggest that language contexts can affect pre-attentive auditory change detection.
Neurophysiological evidence of preattentive English vowel perception in Japanese, Spanish, and Russian learners of English.
Authors: Shafer Valerie L. , Strange Winifred , Ito Kikuyo , Gilichinskaya Yana , Rosas Jason , Kresh Sarah
Published: July 2011

The purpose of this study was to examine preattentive discrimination of English vowel contrasts in Japanese, Spanish, and Russian late learners of English compared to monolingual English listeners. The robustness of discrimination, measured using mismatch negativity (MMN), was predicted to be related to the importance of different types of cues in the native language of listeners (e.g., vowel length for Japanese). Event-related potentials (ERPs) were recorded from a 65-site geodesic net while listeners ignored the speech stimuli and performed a visual target-detection task. The stimuli were natural tokens of forms that differed in vowel (V) category in the first-syllable (e.g., Vpa). One phoneme category served as the frequently-presented standard and two as the rare (deviant) stimuli. Robust MMNs to all vowel contrasts were seen for the native group that was largest over left sites. The non-native groups generally showed smaller MMNs, less left hemisphere contribution, and evidence that the first language influenced preattentive perception. For example, the Japanese listeners showed no MMN for the [aepa] versus [apa] contrast, which differed the least in vowel duration. These findings reveal the highly automatic nature of native language speech perception and that the change-detection process indexed by MMN is sensitive to these processes.
Perceptual confusability of final nasals in Southern Min.
Authors: Chen Ying , Guion-Anderson Susan
Published: July 2011

The three syllable-final nasals /m/, /n/, and /ŋ/ in old Chinese have merged into two (/n, ŋ/) or only one (/ŋ/) nasal in modern Chinese languages. The perceptual confusability of place of articulation was investigated with speakers of Southern Min, a Chinese language which preserves all three final nasals. Three experiments of forced-choice nasal-identification were conducted: (1) complete CVN syllables embedded in noise, (2) CV-truncations of the CVN syllables, and (3) the excised nasal murmur, −N. The first experiment revealed that /m/ was the most and /n/ was the least confusable. Responses were highly accurate in the second experiment (above 85%) and around chance in the third experiment (below 40%), which indicated that listeners relied on the information in the vowel rather than the nasal murmur to identify final nasals. The vowel /i/ resulted in the most and /a/ the least misidentification of final nasals among /i, ə, a/. Low-level and falling tones resulted in more misidentification of final nasals than mid-level, high-level, and rising tones. Segment duration, F0, and formant transitions are analyzed across the vowel and tone types for insight into these findings. Lexical familiarity ratings did not show significant correlation with the perceptual results.
Tone perception cues: Pitch targets, trajectories, or both?
Authors: Ramadoss Deepti , Smolensky Paul
Published: July 2011

Zsiga and Nitisaroj [(2007)] conducted tone perception experiments to test the Moren and Zsiga [(2006)] hypothesis that the principal perceptual cues to the five-way tonal contrast in Thai are high (H) and low (L) pitch targets aligned to (subsyllabic) moras. Their experiments involved perception of synthetic stimuli: manipulated peaks or troughs (corresponding to pitch targets) connected by line-trajectories. In the present study, the stimuli created are intended to be more naturalistic. The hypothesis is that not only peaks and troughs but also the trajectories between them are informative to and important for perception. Manipulations involve realignment of the peaks and troughs, with concomitant compression or expansion of the original trajectory between them. Native Thai speakers categorize the manipulated tone and give a goodness rating. Preliminary data indicate that some categorizations (e.g., manipulated rising perceived as high) can be explained by information present in the trajectory, and not in the peak/trough. However, theories that advocate movements (i.e., trajectories) as perceptual cues [e.g., Xu (2004)] cannot account for some goodness ratings observed in these experiments. Hence, it appears that a combination of the peak/trough information, as well as the trajectory, is employed in tone perception. Work supported by Dr. Luigi Burzio and Dr. Colin Wilson.
Perception of final-consonant “voicing” in whispered speech.
Authors: Gilichinskaya Yana , Strange Winifred
Published: July 2011

The purpose of this study was to examine the accuracy of final consonant perception in whispered speech. Of particular interest was the accuracy of the detection of “voicing” in whispered consonants and its relationship to the prominence of different acoustic cues to consonant voicing. This relationship was investigated for the effect of speaker and consonant. Stimuli were natural tokens that differed in final consonant and vowel preceding it. For example, [habæz] embedded in the carrier sentence “I said testword eight times” produced at a conversational speaking rate. Recordings from four monolingual speakers of American English were used. The consonants were two pairs of stops /b-p/, /g-k/, a fricative-pair /z-s/ and an affricate-pair d ȝ-ʈ ∫. In an eight-alternative forced choice task, listeners indicated which final consonant they heard. Analysis of the results revealed that whispered consonants were identified with a relatively high overall degree of accuracy (84%–88%). ANOVA indicated that identification accuracy was affected by both speaker and consonant. A logistic regression model was used to establish the best predictors of consonant voicing in whispered speech for classification of intended consonants and in predicting the success in [+/− voicing] detection. Predictors that were considered included several acoustic measures, e.g., vowel duration.
Acoustic representations for tonal phonological categories.
Authors: Yu Kristine M.
Published: July 2011

The learnability of tonal categories was investigated by studying how category separability is affected by different phonetic representations of tone. Gauthier et al. [(2007)] found that f 0 velocity contours densely sampled over time were sufficient for near-perfect categorization of Mandarin tones. Since infant learners begin as “citizens of the world” before developing language-specific representations of sound categories in response to ambient language input [Kuhl (2004)], cross-linguistic data were studied. Based on tonal production data from Bole, Igbo, Mandarin, Cantonese, and White Hmong, we found that (1) densely sampled f 0 velocity contours are insufficient for learning tones, but (2) coarse temporal sampling of phonetic features can produce well-separated tonal categories, and moreover, that (3) phonetic features for tonal representation necessarily extend beyond f 0 to voice quality features, and (4) features for tonal representation are language-specific. Results (2) and (3) were also supported by tonal perception experiments in Cantonese. It was found that listeners can maintain tonal identification accuracy under coarse sampling (down to three to five samples per syllable), with the speech signal interrupted with noise as in multiple phoneme restoration experiments. It was also found that listeners are biased in tonal identification by creaky voice in the speech signal.
Differentiating between gay and heterosexual male speech.
Authors: Tracy Erik C. , Satariano Nicholas P.
Published: July 2011

How many phones do listeners need to hear in order to discriminate between gay and heterosexual male speakers? Prior research [Munson et al. (2006) has found that listeners only need to hear a single monosyllabic word to make this determination. In a series of experiments, listeners heard monosyllabic words and portions of these words, and were able to discriminate between gay and heterosexual male speakers. Experiment 1 replicated the prior results. In experiment 2, listeners were above chance in differentiating between heterosexual and gay male speakers when presented with specific phonemes, such as /s/ and certain vowels (/eɪ/, /u/, /i/, /ɛ/, //aelig/). These data extend prior work demonstrating that gay and heterosexual men produce certain phones differently [Linville (1998); Pierrehumbert et al. (2004)]. When presented with other phonemes (/n/, /m/, /f/, /v/, /l/, /w/), listeners were not as accurate in differentiating between gay and heterosexual male speakers. These results suggest that listeners were able to accurately discriminate between gay and heterosexual speakers when presented with specific phonemes, although they were relatively more accurate in their determinations when presented with the entire monosyllabic word.
Perception of a computational model of hypernasality: A mixed methods study.
Authors: Plichta Bartek , Watson Peter J.
Published: July 2011

Most synthesis of nasal resonance is implemented by means of a parametric synthesizer [Klatt & Klatt, (1990)], offering a high degree of control, but having machine-generated quality [Zraik et al., (2000)]. Typically this method is used to synthesize only small speech segments (i.e., sustained vowels and syllables; generating sentence-long samples is time-consuming and difficult to implement in batch mode. The alternative to parametric synthesis is LPC analysis/resynthesis because it is capable of producing natural output, but attempts to synthesize hypernasality by means of LPC analysis/resynthesis have been largely unsuccessful [Eriksson et al., (2003)]. We synthesized sentence-length stimuli with different degrees of nasality using a new technique based on the work of Chen [(1995)]. To evaluate our stimuli we used a sequential explanatory design: Quantitative data were used to rate hypernasality with different degrees of added nasal resonance; and qualitative data were used to evaluate the perception of quality and naturalness of the stimuli. The combined results of both analyzes showed that the ten speech-language pathologists (SLPs) rated the degree of perceived hypernasality in accord with the degree of nasality synthesized in the stimuli, and the SLPs queried rated the overall quality of the synthesis favorably and uniformly.
Does hyperarticulation facilitate phonemic categorization in non-native speakers of English?
Authors: Uther M. , Giannakopoulou A. , Iverson P.
Published: July 2011

Hyperarticulation of vowel sounds occurs in certain speech registers (e.g., infant- and foreigner-directed speeches). Hyperarticulation is therefore presumed to have a didactic function in facilitating phonetic categorization in language learners. This event-related potential study tests whether hyperarticulation of vowels actually results in larger phonetic change responses [as indexed by mismatch negativity (MMN)] in native and non-native speakers of English. Preliminary analysis of data from native English-speaking and native Greek-speaking participants suggests a possible marginal increase in phonetic change responses (as indexed by MMN) to hyperarticulated stimuli. However, further analyzes need to be completed before any firm conclusions can be drawn as to the benefit or otherwise of hyperarticulated speech.
The classification of Greek fricatives with cepstral coefficients.
Authors: Athanasopoulou Angeliki , Vogel Irene
Published: July 2011

This study examines the classification of Greek fricatives based on place and manner of articulation. Greek is particularly rich in fricatives, so a total of 10 segment types are considered: voiced and voiceless segments at five places (labial, dental, alveolar, palatal, and velar). For each segment the first five bark-cepstral coefficients were extracted and the values were used in a linear discriminant analysis to separate the different place categories in a statistically optimal way. Data from ten native Greek speakers are currently being analyzed, and preliminary results indicate that the classification of Greek fricatives is generally comparable to that of a similar study with Romanian fricatives [Spinu, L. (2010); Palatalization in Romanian: Experimental and theoretical approaches, Ph. D. thesis University of Delaware.], where overall accuracy of the classification was 78%. Nevertheless, since the inventory of modern Greek fricatives is rather different from that of Romanian, and it crucially includes a contrast between labials and interdentals, which has traditionally posed problems to this type of analysis; it is anticipated that some differences will also be observed. This, in turn, will provide further insights into the nature of fricatives across languages.
Perceptual similarity, response bias, and novel phonetic categories.
Authors: Silbert Noah H. , Smith Benjamin , Campbell Susan , Doughty Catherine
Published: July 2011

Numerous studies show a close correspondence between categorization of stimuli from a voice onset time (VOT) continuum and native language category structure. Relatively little is known about the relationships between perception, response bias, and the assignment of novel, non-native categories to tokens varying in VOT. Data from two categorization tasks in which VOT continua spanned portions of English voiceless (task 1) and voiced (task 2) categories were analyzed with a hierarchical Bayesian signal detection model in an exploratory study of these relationships. In both data sets, high-accuracy listeners show roughly equally spaced perceptual distributions and no response bias, whereas low accuracy subjects exhibit substantial variability and consistent bias to respond with categories that were not those most closely aligned with the closest native category. The model also provides a rigorous, theoretically-motivated measure of perceptual similarity, which in turn enables quantitative exploration of links between categorization behavior and popular theories of speech perception (e.g., the perceptual assimilation model and native language magnet theory). Analysis of similarities between tokens suggests a small, but consistent, perceptual magnet effect in both high- and low-accuracy groups.
Do language-specific differences in primary acoustic cues affect relative weighting of secondary cues to phonological contrasts?
Authors: Francis Alexander L. , Llanos Fernando , Dmitrieva Olga , Chapman Rachel
Published: July 2011

Cross-language differences in cue weighting are often attributed to differences in phonological inventories, in that listeners are assumed to give greater weight to those acoustic cues that best differentiate the specific phonological categories of their native language. However, subphonological properties of a given contrast may also affect weighting of acoustic cues for acoustic or perceptual reasons, in a manner independent of the structure of the listeners’ phonological inventory. Here, this possibility is investigated by comparing Spanish and English listeners’ relative weighting of two acoustic cues to the syllable-initial stop consonant voicing contrast /b/-/p/: Voice onset time (VOT) and fundamental frequency at the onset of voicing (onset f0). Spanish and English possess comparable word-initial stop consonant inventories, but differ in the phonetic realization of the voicing contrast in terms of VOT: Spanish contrasts a short lag (<10 ms) /p/ with a prevoiced (<0 ms) /b/, while English contrasts a long lag (> 50 ms) /p/ with a short lag (<20 ms) /b/. Preliminary results (N = 7) suggest that, although speakers from both languages depend mainly on VOT, Spanish speakers give more weight to onset f0 when VOT is ambiguous than do English listeners.
Comparing weights of cues with different numbers of levels.
Authors: Kapatsinski Vsevolod , Shport Irina , Guion-Anderson Susan
Published: July 2011

Cue weighting is a useful methodological tool in speech perception research: it allows to access within-group and between-group biases in sound categorization. Examination of cue weighting may also have major implications for phonological theory. For instance, significant individual variation in reliance on cues to a phonemic contrast within a speech community challenges the traditional assumption of the language-specific feature system. Morrison argued that logistic regression coefficients in identification tasks provide good estimates of cue weights [Studies in Second Lang. Acquisition 597–606 (2005)]. Unfortunately, coefficient estimates vary with the number of levels a cue has, which makes it impossible to directly compare weights of cues with different numbers of levels, a serious limitation. The present paper shows that, using a null hypothesis of zero cue weight and a fixed sample size, one can employ Monte Carlo techniques to estimate the effect of the number of levels on observed cue weights (regression coefficients). One can then test whether the difference in the number of levels between cues can account for the observed difference in weights. If not, then the cue weights are reliably different. The method is demonstrated on data investigating individual variation in attention to cues to pitch accent.
The role of formant-frequency contours in the perceptual grouping of speech formants.
Authors: Roberts Brian , Summers Robert J. , Bailey Peter J.
Published: July 2011

The perceptual organization of speech remains poorly understood. Recent research using sine-wave speech suggests that the ability of an extraneous formant to impair intelligibility depends on modulation of its frequency contour [Roberts et al., J. Acoust. Soc. Am. 128, 804–817]. This study examined the effect on intelligibility of manipulating the depth of this frequency variation. Three-formant (F1+F2+F3) analoges of natural sentences were synthesized using a monotonous glottal source (F0=140 Hz). Each formant-frequency contour was scaled to 50% depth about its geometric mean; this manipulation had relatively little impact on intelligibility. Perceptual organization was probed by presenting stimuli dichotically (F1+F2C; F2+F3), where F2C is a competitor for F2 that listeners must resist to optimize recognition. Different competitors were created by inverting the frequency contour of F2 about its geometric mean and varying its depth (100%-0%, 25% steps). Adding F2C typically reduced intelligibility; this reduction was greatest for 100%-depth, intermediate for 50%-depth, and least for 0%-depth (constant) F2Cs. These results indicate that competitor efficacy depends on overall depth of frequency variation, not depth relative to that of the other formants, and suggest that frequency-contour modulation influences across-formant grouping not only in sine-wave analogues but also in more speech-like simulations. [Work supported by EPSRC.]
From seismic stratigraphy and oil hunting to three-dimensional geo-acoustic databases for acoustic modeling.
Authors: Lowrie Allen
Published: July 2011

This work describes a conceptually possible methodology to construct 3D multi-layered geo-acoustic databases in absense of extensive data, based on geologic first principles. Remote sensing of the sediment-covered seafloor by seismic reflection data over continental margins provides for reflector interpretation with correlations between seismic and geologic data, identifying sedimentary processes with energy levels. Realization of individual reflectors denoting a later deposition onto a pre-existing surface opens the determination of individual depositional sequences from seismic reflection data. Such interpretation permits determining single deposition with sediments from one range of sealevels over definite regions and time-units. At periodicities from 20 000–100 000 years, sealevels oscillate 25–125 m due to climate with waters “stored” on continents as ice. A specific sequence suggests sediment-types deposited with geo-acoustic values applicable. From worldwide seismic data with sequence dates verified by drillhole-groundtruth, a stratigraphy of sealevel position with time exists. For past-time-ranges, sealevel position and depositional characteristics are known. Geologic history including globally dated climate/sealevel/sedimentation oscillations means that sediments and geo-acoustics for a given time may be interpreted without seismic and/or core/drillhole data. A synthetic database of geo-acoustic values in a 3D real-world format is constructable. Thus, actualistic databases based on data and without may be constructed.
Mid-frequency geoacoustic inversion using bottom loss data from the Shallow Water 2006 Experiment.
Authors: Yang Jie , Jackson Darrell R. , Tang Dajun
Published: July 2011

Geoacoustic inversion work has typically been carried out at frequencies below 1 kHz, assuming flat, horizontally stratified bottom models. Despite the relevance to Navy sonar systems, many of which operate at mid-frequencies (1–10 kHz), limited inversion work has been carried out in this frequency band. This paper is an effort to demonstrate the viability of geoacoustic inversion using bottom loss data in the frequency band of 2–5 kHz. The acoustic measurements were taken during the Shallow Water 2006 Experiment off the coast of New Jersey. A half-space bottom model, with three parameters, density, compressional wave speed, and attenuation, was used for geoacoustic inversion by fitting the model to data in the least-squares sense. Inverted sediment sound speed was compared with direct measurements and inversion results using different techniques in the same area. The comparison shows that bottom loss can be used to infer sediment geoacoustic parameters at mid-frequencies. In addition, observations and modeling results demonstrate that forward scattering from topographical changes is important at mid-frequencies and should be taken into account in sound propagation predictions and geoacoustic inversion. To cope with fine-scale topographic variability, measurement technique such as averaging over tracks may be necessary.