bluuebunny/crossref_metadata_2025 huggingface dataset:
Current-eddy interaction in the Agulhas Return Current region from the seismic oceanography perspective
Authors: Rice Ana E. , Book Jeffrey W. , Wood Warren T. , Fischer Tim
Published: May 2013

Interleaving in the Agulhas Return Current (ARC) frontal region is commonly manifested in the form of thermohaline intrusions, as sub-tropical and sub-polar water masses of similar density meet. In Jan./Feb. 2012, the Naval Research Laboratory and collaborators carried out a field experiment in which seismic and traditional hydrographic observations were acquired to examine frontal zone mixing processes. The high lateral resolution (10 m) of the seismic observations allowed fine-scale lateral tracking of thermal intrusions, which were corroborated with simultaneous XBT casts. Between seismic deployments both salinity and temperature data were acquired via CTD, underway-CTD and microstructure profiles. This study focuses on analyzing seismic reflection data in a particular E-W transect where the northward flowing ARC interacted with the southward flowing portion of a large anticyclonic eddy. Strong reflectors were most prominent at the edge of a hyperbolic zone formed between the eddy and ARC, where sub-polar waters interacted with waters of sub-tropical origin on either side. Reflectors were shallow within the hyperbolic zone and extended to 1200 m below the ARC. The nature of the observed reflectors will be determined from comparison of seismic reflection and derived ∂T/∂z fields, and XBT and TS profiles from the available hydrographic data.
Cavitation-induced streaming in shock wave lithotripsy
Authors: Pishchalnikov Yuri A. , McAteer James A.
Published: May 2013

Cavitation generated by lithotripter shock waves (SWs) in non-degassed water was studied using a 60 frames-per-second camcorder—recording the migration of microbubbles over successive SWs. Lithotripter SWs were produced using a Dornier DoLi-50 electromagnetic lithotripter at 0.5 and 2 Hz pulse repetition frequency (PRF). Cavitation was affected by PRF and by the power level (PL) of the lithotripter. At slow PRF, such as shots fired many seconds apart, cavitation was relatively sparse and bubble clouds flowed in the direction of SW propagation. When PRF was increased, the bubble clouds generated by one SW were amplified by subsequent SWs. Cloud amplification was accompanied by an apparent change in the pattern of bubble migration. Whereas bubbles continued to enter the field of view from the prefocal side, the main bubble cloud remained near the focal point. This was due to a streaming of bubbles opposite to the direction of SW propagation. Increasing the PL grew the cavitation field and enhanced the flow of bubbles opposite to the direction of SW propagation. Stepping up the PL acted to push the broad cloud progressively pre-focally (toward the SW source), shifting the position of the plane at which the opposing directional bubble flows collided. [NIH DK43881.]
Examination of acoustic mechanism for compact acoustic reproduction systems
Authors: Sugihara Kosuke , Nakamura Masashi , Kajikawa Yoshinobu , Nomura Yasuo , Miyakura Takashi
Published: May 2013

In this paper, we propose a method for analyzing compact acoustic reproduction systems (e.g., mobile phones) through acoustic equivalent circuits. Measured responses of compact acoustic reproduction systems cannot be represented accurately by the analysis based on the conventional acoustic theory. Acoustic engineers consequently are obliged to design compact acoustic reproduction systems by trial and error. Moreover, the sound quality of those systems is likely to deteriorate due to the difficulty of such an acoustic design. We therefore clarify the cause of the difference between the measured response and the analysis one calculated by the finite element method (FEM) analysis and consider the possibility of obtaining new acoustic theoretical formula based on the analysis results in order to make it easier for acoustic engineers to design compact acoustic reproduction systems.
Experience teaching acoustics at the senior-undergraduate and first-year graduate levels
Authors: Dowling David R.
Published: May 2013

Perhaps without appreciating it, college students are more fully equipped to understand and study acoustics than any other field of science. This assertion stems from the fact that most college students have two exquisite broadband receivers with impressive dynamic range (ears), and a matched multi-functional sound projector (voice). Given that nearly all college students have used their ears and voice for many years before arriving in an acoustics classroom, the advanced-acoustics instructor’s task is primarily to link theoretical results with the acoustic intuition that students already possess. Thus, a worthy pedagogical goal is to activate this submerged knowledge and connect it to mathematical results through practical examples, classroom demonstrations, and relevant homework. At the senior-level, useful demonstrations include the following: acoustic resonances of a cardboard tube, the dipole characteristics of small raw loudspeaker, directional reflection with a metal salad bowl, and sound volume changes as a loud speaker is lifted out of a cabinet. At the graduate level, useful homework assignments include boundary-element and finite-element calculations with commercial software that can be checked with established theory. In addition, worthwhile homework problems that attempt to provide sufficient reward for students who master the mathematical content have been developed for both classes.
Effective techniques and crucial problems of numerical study on flue instruments
Authors: Takahashi Kin'ya , Iwasaki Takuya , Akamura Takahiro , Nagao Yuki , Nakano Ken'ichiro , Kobayashi Taizo , Takami Toshiya , Nishida Akira , Aoyagi Mutsumi
Published: May 2013

In the last several decades, there have been many important proposals for study on flue instruments from theoretical and experimental points of view. Analyses based on aerodynamic sound theory are crucial for understanding the sounding mechanism of flue instruments. According to the growth of computer power and the improvement of numerical schemes, numerical simulations based on fluid dynamics now become important tools for the study of aerodynamics sound. In this talk, we will discuss accuracy, efficiency, and reliability of numerical calculations with large-eddy-simulation (LES) of compressible flow and we will show to what extent LES can reproduce the fluid and acoustic behavior of flue instruments observed experimentally. Furthermore, we will consider how to calculate the important theoretical formulae of aerodynamics sound theory, e.g., Lighthill’s quadrupole, Powell-Howe vortex sound source, Howe’s formula that allows us to estimate the energy transfer between the acoustic field and the hydro-dynamic field. Actually, those quantities given by the theoretical formulae play an important role in the analyses of sounding mechanisms of flue instruments. M. Miyamoto et al., “Numerical study on acoustic oscillations of 2D and 3D flue organ pipe like instruments with compressible LES,” Acta Acustica (accepted for publication).
The effect of the shadowing phenomenon on emergency vehicle siren noise
Authors: D'Angela Peter J. , Angione Frankie , Novak Colin , Ule Helen
Published: May 2013

It has been observed by some that emergency siren noise has gone unnoticed by drivers due to a shadowing phenomenon where the propagating siren noise is blocked from a receiver vehicle. The event is postulated to occur when a large vehicle is positioned between the emergency responder and a receiving vehicle. The sound of the siren is projected along the surface of the large vehicle and does not fall in time to reach the receiving vehicle. This situation is common at controlled intersections where the smaller vehicle is traveling perpendicular to the emergency vehicle but can also occur when the vehicles are in a common line on the road. The intent of this study is to investigate this phenomenon and quantify the resulting hindrance of a driver’s ability to detect an approaching emergency vehicle. Included will be the use of the electrical “wail” siren and accompanying air horn commonly employed by Fire and Rescue Services. The outcome will be a determination of what frequency spectra are most affected by shadowing with an eventual goal to improve emergency siren design.
Detectability and annoyance of warning sounds for electric vehicles
Authors: Parizet Etienne , Robart Ryan
Published: May 2013

Electric or hybrid vehicles are very quiet at low speeds, which represents a very good opportunity to reduce traffic noise annoyance in cities. On the other hand, this may be very hazardous for vulnerable pedestrians (e.g., visually impaired people). The aim of the eVADER project is to propose solutions in order to add warning sounds to such cars, while fulfilling two contradictory goals: sounds should be detectable but should not contribute to traffic noise annoyance. Different perceptual experiments have been conducted: the first one evaluated the influence of various timbre parameters on sound detectability. It was shown that an electric vehicle equipped with one particular sound was as easily detected as a diesel one, while keeping a very low level. Then, the influence of some timbre parameters (pitch and temporal modulation frequency) on the distance and speed as perceived by listeners was measured. These two experiments were conducted with sighted and visually impaired subjects. Finally, a third one evaluated the consequence on traffic noise annoyance of such warning sounds.
Measurement, evaluation, and analysis of noise and vibrations produced by an Argentinean medium tank
Authors: Chorubczyk Alan , Ruffa Francisco , Urquiza Nicolás , Margaretic Pablo , Morandi Damián , Piegari Andrés , Ausili Sebastián
Published: May 2013

In the present paper it is presented the procedure of measurement, evaluation and results’ analysis of an Argentinean medium tank T.A.M. Since there is no regulation on noise emissions and vibrations caused by combat units either inside or outside the vehicle, standards that evaluate similar situations were used. Then, noise and vibrations inside the moving vehicle and noise emissions of acceleration and static situations were assessed. Consequently, the procedure and results were analyzed in order to propose a proper heavy combat units assessment procedure.
Contribution analysis of vehicle exterior noise with operational transfer path analysis
Authors: Putner Jakob , Lohrmann Martin , Fastl Hugo
Published: May 2013

Vehicle development regarding the emitted exterior noise is a challenging task. In addition to stringent legal requirements to reduce noise exposure, also high expectations of the sound quality have to be considered during the development process. In order to manipulate the vehicle exterior noise in a manner more efficient than trial and error, knowledge about the vehicle’s sound sources, and their contributions to the overall noise is essential. In order to analyze the contributions of the several sound sources of a vehicle to the exterior noise Operational Transfer Path Analysis is used in the presented experiment. Therefore, transfer characteristics are estimated from measurements of the vehicle in typical operating conditions on an acoustic roller dynamometer. These data are used to synthesize the contributions at the response positions, i.e., the microphones of a simulated pass-by array, which also allow the simulation of the contributions during a pass-by measurement. Outcomes of the Operational Transfer Path Analysis are comprehensible contributions of the dominant sound sources to the vehicle exterior noise. The validation of the analysis results shows very good accordance between the simulated and measured overall vehicle exterior noise.
Developing noise standards for future supersonic civil aircraft
Authors: Cowart Robbie
Published: May 2013

With renewed interest in civil supersonics, NASA and industry researchers continue to make progress toward enabling quiet civil supersonic aircraft. Gulfstream Aerospace has long been interested in the development of an economically viable supersonic business jet; however, many regulatory challenges still remain for routine supersonic operation. Gulfstream’s approach includes unrestricted supersonic flight over land to enable the same operational flexibility of its subsonic fleet. The largest technical barrier to achieving this end is mitigating the sonic boom created by flying at cruise speeds greater than Mach 1.2. At present, the United States and many other countries prohibit supersonic flight over land due to the loudness and public annoyance associated with sonic boom noise. In the United States, the FAA prohibits supersonic flight under FAR 91.817. Although the FAA has shown interest in reconsidering its position, the agency supports the noise and emissions standards setting process through the International Civil Aviation Organization and its Committee on Aviation Environmental Protection. Development of future standards for sonic boom noise is a key component to enabling continued investment in civil supersonic research. This paper will outline the steps currently underway to assess the viability of defining low amplitude supersonic signature acceptability.
Source localization results for airborne acoustic platforms
Authors: Ostashev Vladimir E. , Cheinet Sylvain , Collier Sandra L. , Reiff Chris , Lygon David A. , Wilson D. Keith , Noble John M. , Alberts, II William C.
Published: May 2013

Acoustic sensors are being employed on airborne platforms for source localization. Under certain atmospheric conditions, airborne sensors offer a distinct advantage over ground sensors. Among other factors, the performance of airborne sensors is affected by refraction of sound signals due to vertical gradients in temperature and wind velocity. A comprehensive experiment in source localization with an aerostat-mounted acoustic system was carried out in July 2010 at Yuma Proving Ground (YPG). Acoustic sources on the ground consisted of one-pound TNT denotations and small arms firings. The height of the aerostat was approximately 1 km above the ground. In this paper, horizontal, azimuthal, and elevation errors in source localization and their statistics are studied in detail. Initially, straight-line propagation is assumed; then refraction corrections are introduced to improve source localization and decrease the errors. The corrections are based on a recently developed theory [Ostashev et al., J. Acoust. Soc. Am. (2008)] that accounts for sound refraction due to vertical profiles of temperature and wind velocity. During the 2010 YPG field test, the vertical profiles were measured only up to a height of approximately 100 m. Therefore, the European Center for Medium-range Weather Forecasts (ECMWF) is used to generate the profiles for July of 2010.
A numerical approach to the climatology of near-surface sound levels
Authors: Cheinet Sylvain
Published: May 2013

The near-surface sound levels propagated at distance from a known source show a large variability on the long term. This variability is essentially caused by the weather-dependence of the refractive characteristics: wind and temperature stratifications, turbulence. An approach to document this variability is to simulate the sound propagation under these varying characteristics at the selected site. This study uses a numerical model which physically describes the sound propagation including in presence of turbulence. The model is based on the parabolic equation, it ingests standard atmospheric parameters as input. The predicted sound levels for an example 40 Hz-frequency sound propagating at a 1.5 km-range are shown to combine the impacts of stratification and turbulence. The results are used to form the sound level climatology at several sites over the globe, based on existing climatological data. The obtained statistics are modulated by the dominant wind regimes, the seasonal and diurnal cycles. The sensitivity of these results to turbulence assessment is discussed.
Guided waves scattering by discontinuities near pipe bends
Authors: Predoi Mihai V. , Petre Cristian C.
Published: May 2013

Guided waves became in recent years an useful tool in nondestructive testing of pipes used in many industrial applications. The torsional and longitudinal waves in pipes are the main choice for integrity inspection. The first step is the computation of the dispersion curves, for straight pipes. Since most pipes have bends, the problem of guided modes in the toroidal segment remains of interest. Various methods have been applied to solve this problem. The most promising numerical method to obtain the dispersion curves for a torus is based on finite elements (FE), using a standing waves model. Based on these dispersion curves, transmissions of longitudinal and torsional waves through a bend were also investigated. The present paper presents the scattering process produced by geometrical discontinuities such as circumferential welds before and after a pipe bend. Longitudinal L(0,2) mode is sent along the straight pipe in FE simulations, toward the bend. Reflected and transmitted modal amplitudes are determined for frequencies of interest. The capability of detecting a defect close to one of the two welds is thus assessed. The modes transmitted past the bend are also characterized. Comparisons with results obtained by other researchers are used to validate the method.
Auditory discrimination on the distance dependence of near-field head-related transfer function magnitudes
Authors: Liu Yu , Xie Bosun
Published: May 2013

Distance dependence of head-related transfer functions (HRTFs) for nearby sound sources within 1 m is regarded as one of auditory distance perception cues. Accordingly, the near-field HRTFs have been used to synthesize sound sources at different distances in virtual auditory display. The present work analyzes the audibility of variation in near-field HRTF magnitudes with source distance. The calculated near-field HRTFs from KEMAR artificial head with a distance resolution of 0.01 m and a binaural model are used in analysis. The changes in loudness level spectra and interaural level difference are used as audible criteria. The result indicates that, as source distance decreases, the variation in HRTF magnitude with source distance become prominent and thereby audible. A psychoacoustic experiment is also carried out to validate the analysis. This work provides insight into the distance resolution of near-field HRTFs required in binaural virtual source synthesis.
Issues in binaural hearing in bilateral cochlear implant users
Authors: Kan Alan , Jones Heath , Litovsky Ruth Y.
Published: May 2013

Despite the success of bilateral cochlear implants (CIs) in restoring sound localization abilities in profoundly deaf individuals, their localization accuracy is still poorer than that of normal hearing listeners. One factor could be the behind-the-ear location of the microphones. However, when CI users were tested with stimuli filtered through individualized head-related transfer functions (HRTFs), they showed very little difference in sound localization performance with different microphone locations (behind-the-ear versus in-the-ear). Another factor is the different implantation depths of the electrode arrays at the two ears. Since CIs are typically fitted independently in each ear at the clinic, it is likely that binaural information at a particular frequency can be presented mismatched across the ears. By simulating different amounts of interaural frequency mismatch at single electrode pairs, CI users showed poorer fusion and lower binaural sensitivity with increasing interaural mismatch. Good lateralization and fusion was achieved on or near a pitch-matched pair of electrode. Additionally, results from a separate study showed lateralization performance was typically maintained with simultaneous stimulation of multiple, pitch-matched pairs of electrodes. These results demonstrate methods beyond just changing the microphone position are needed to improve sound localization performance in CI users. [Work supported by NIH-NIDCD (R01-DC003083) and NICHD (P30-HD03352).]
The effect of accommodation on perceived vocal aesthetics
Authors: McGuire Grant L. , Babel Molly , Russell Jamie
Published: May 2013

We conducted an auditory naming task (n = 20) using eight model talker voices previously rated for attractiveness and prototypicality such that the most attractive, least attractive, most typical, and least typical voice for each gender served as a model talker. Female shadowers accommodated more than males, particularly to the Most Attractive Female model. This finding led us to question if in the course of accommodation to an attractive female voice, female shadowers themselves become more vocally attractive. We then conducted an AX task where listeners judged whether shadowers’ baseline or shadowed productions were more attractive. Our results suggest that shadowers do modulate their perceived attractiveness in the course of accommodating; in particular, the more females accommodated to the Most Attractive Female model, the more attractive her own voice became. We are currently running a second study exploring whether shadowers’ voices change in perceived typicality when accommodating the Most Typical and Least Typical voices, both of which also garnered large amounts of accommodation in the original auditory naming task. In general, our results demonstrate that the process of accommodation involves the mirroring of multidimensional speech characteristics, which in turn signal vocal aesthetics to listeners.
Coordinating conversation through posture
Authors: Oberg Martin A. , Vatikiotis-Bateson Eric , Barbosa Adriano
Published: May 2013

Conversation is dynamic and interactive. The importance of coordinated movement in conversation has been studied through perceptual measures of synchrony and recently through quantitative analyses of multi-dimensional motion data. The present study describes the postural system as being integrated with the communication process through an analysis of interlocutors' coordination of rigid-body head motion, postural shifts on forceplates, and motion computed from audio-visual recordings. Coordination is measured two ways: (1) holistically, as the scaling of speakers' motion over the duration of a conversation (i.e., the presence of movement encourages more movements) and (2) through analyses of the instantaneous correlation between motion signals from each speaker (i.e., a search for similar patterns of movement across time). These two approaches are evaluated in their ability to categorize conversation types. Preliminary results show that a stability emerges in the amount of correlation across conversations. Variations in the pattern of stability are analyzed as evidence of differences between general interactional coordination and linguistic coordination.
The role of voice similarity in accommodation
Authors: Walters Sophie A. , Babel Molly , McGuire Grant
Published: May 2013

Studies of accommodation show that some talkers are perceived as accommodating more than others. One possibility is that the similarity of the shadower's voice to a model talker's can account, in part, for the amount of perceived accommodation. To determine this, we conducted an auditory naming task having eight model talker voices previously rated for attractiveness and prototypicality, such that the Most Attractive and Least Attractive and Most Typical and Least Typical voices for each gender were used as models. Twenty participants completed an auditory naming task with these eight voices. A separate group of 20 listeners rated the similarity of model tokens and shadower’s baseline productions using a visual analog scale. The results of this task were compared to the perceived accommodation results from a separate AXB rating task. Overall, female voices that were more different from the models showed more accommodation. This effect was not found for males, who generally showed less accommodation overall. These findings suggest that talkers either accommodate more when their voice is more distinct from the model talker's voice, or perhaps more likely, that such changes are more perceptible to listeners. Further explorations of the data are underway to tease apart these possibilities.
Effects of acoustic variability on infant speech perception
Authors: Archer Stephanie L. , Curtin Suzanne , Polka Linda
Published: May 2013

From birth, infants are capable of discriminating many of the speech sounds that occur cross-linguistically [Werker and Tees (1984)]. However, there are cases where the direction of presentation of contrasts reveals asymmetries in the discrimination of some speech contrasts, suggesting that some phonetic categories are more salient than others. These asymmetries may be due to an inherently uneven perceptual space [Polka and Bohn (2011)] or shaped by distributional properties of the input [Anderson et al. (2003)]. We explore whether acoustic variability also cause perceptual asymmetries. Six- and 9-month-olds participated in a discrimination task comparing English legal and illegal stop-liquid onsets (e.g., /kla/-/tla/ & /pla/-/tla/). Infants discriminated coronal versus bilabial onsets (p < 0.05), but not coronal versus velar (p > 0.05). Analysis of adult productions revealed that velar stop-liquid onsets showed more variability in their production, suggesting acoustic variability affects infants’ perception. The current study provides a more direct test of the hypothesis that acoustic variability drives perceptual biases. Using the same clusters, we are exploring 9-month-olds’ directional asymmetries. Preliminary results show that 9-month-olds successfully discriminate /dla/ after familiarization to /bla/ (p = 0.05; n = 5). Further investigation will reveal whether presentation direction affects infants’ sensitivity to acoustic variability.
Infant recognition of infant vocal signals
Authors: Masapollo Matthew , Polka Linda , Menard Lucie , Vouloumanos Athena
Published: May 2013

Most of the speech accessible to infants who are not yet babbling will not have infant vocal properties; yet their perception of infant vocal signals is critical for speech development. We report three experiments designed to assess whether 4- to 5-month-olds recognize and preferentially attend to vowels produced by infant talkers over vowels produced by adult talkers. Infants were tested in a sequential preferential looking procedure using isolated vowels synthesized by VLAM. In experiment 1, infants listened significantly longer to vowels produced by an infant talker than an adult (female). In experiment 2, infants failed to show any listening preference for infant versus adult vowels synthesized with matching (infant-appropriate) f0 values, suggesting that infants either recognized the un-natural pairing of f0 and formant structure in these adult vowels or are attracted to high f0 values. Failing to support the latter interpretation, infants in experiment 3 showed no listening preference when presented infant vowels with different (infant-appropriate) f0 values. Together, these findings suggest that young infants recognize the converging vocal (source and filter) properties that specify an adult and an infant talker. These recognition skills appear to be available prior to babbling, and thus are available to support early vocal learning.
Serial order recall for rapid auditory presentations of vowel sequences: The effect of age
Authors: Fogerty Daniel , Humes Larry E.
Published: May 2013

Temporal processing declines with age may reduce memory of rapidly presented auditory sequences. The current experiment investigated vowel sequence recall for two- and four-item vowel sequences presented at six different stimulus onset asynchronies (SOA) that spanned identification performance at 50% correct. Young, middle-age, and older adults participated in all tasks. For two-item sequences, a functional difference was observed between the age groups. Older and younger listeners had a qualitatively different pattern of recall, while performance for the middle age group approximated performance of either the young or older group, dependent upon the presentation rate (i.e., SOA). For the four-item sequences, results demonstrated the standard serial position curve. Increasing the rate of presentation by decreasing the SOA had the most profound effect on the middle items of the sequence for which subjects had the poorest retention. Overall, when temporal order performance was equated at the presentation rate corresponding to each individual’s 50% threshold, recall accuracy for each position across the age groups was highly similar. These results suggest that declining temporal order performance of rapid sequences for older listeners is not the result of poorer recall performance, but is more related to sensory processing declines of rapidly presented temporal sequences.
Compensatory articulation in amyotrophic lateral sclerosis: Tongue and jaw interactions
Authors: Shellikeri Sanjana , Yunusova Yana , Thomas Danielle , Green Jordan , Zinman Lorne
Published: May 2013

Previous acoustic studies on speech deterioration in amyotrophic lateral sclerosis (ALS) demonstrated that those at more advanced stages of disease show reduced F2 (second formant) slopes presumably due to disease-related changes in the tongue. Other studies have shown that patients with ALS use their jaw to compensate for decreased tongue function in speech. However, no study to date has examined the compensatory role that the jaw has on maintaining the acoustic signatures of vocalic segments. This study will report F2 slope differences in vowels and diphthongs produced with and without jaw stabilization via a bite block. Based on previous studies, I hypothesized that the bite block will affect F2 slope measures in individuals with significant tongue impairment on the oral-motor examination and low speech intelligibility scores. Thirty participants repeat a carrier phrase “Say _ again” with words “wax, sip, yo-yo, sight” three times with and without the bite block. Kinematic measures of the distance, time, and speed, and acoustic measures of F2 slope are reported. The data will be discussed in the context of the role of the tongue in vowel production.
Relationship between articulation and mispronunciation detection in children with speech delay: Perception of unfamiliar speech vs. their own speech
Authors: Paullin Mark , Nagao Kyoko , Bunnell H Timothy
Published: May 2013

We examined the relationship between speech production and mispronunciation detection ability in children with speech delay (SD). Thirty-three SD children aged between 6;0 and 10;0 participated in a mispronunciation detection test using three types of stimuli: words pronounced correctly by other unfamiliar children (OTHERS); words mispronounced by OTHERS; and the participant’s own speech (SELF) pronounced either correctly or incorrectly. The participant’s articulation was assessed by the standardized GFTA-2 scores. Results indicated that SD children made significantly more errors when judging SELF speech than when judging OTHERS speech. Multiple regression analyses revealed that accuracy of detecting OTHERS mispronounced words was a significant predictor of GFTA-2 scores in these SD children. Interestingly, in the regression model, accuracy for detecting SELF mispronunciations made a significant independent contribution in addition to accuracy at detecting OTHERS mispronunciations. Overall these two measures accounted for a significant proportion of the variance in GFTA-2 scores (R-squared = 0.45). These findings suggest that children with SD may have more coarse phonological representations of their own speech than the speech of other children.
What you see is what you hear: How visual prosody affects artificial language learning in adults and children
Authors: Brar Jaspal K. , Tyler Michael D. , Johnson Elizabeth K.
Published: May 2013

Speech perception is a multimodal phenomenon, with what we see impacting what we hear. In this study, we examine how visual information impacts English listeners’ segmentation of words from an artificial language containing no cues to word boundaries other than the transitional probabilities (TPs) between syllables. Participants (N = 60) were assigned to one of three conditions: Still (still image), trochaic (image loomed toward the listener at syllable onsets), or Iambic (image loomed toward the listener at syllable offsets). Participants also heard either an easy or difficult variant of the language. Importantly, both languages lacked auditory prosody. Overall performance in a 2AFC test was better in the easy (67%) than difficult language (57%). In addition, across languages, listeners performed best in the trochaic condition (67%) and worst in the Iambic condition (56%). Performance in the still condition fell in between (61%). We know English listeners perceive strong syllables as word onsets. Thus, participants likely found the Trochaic Condition easiest because the moving image led them to perceive temporally co-occurring syllables as strong. We are currently testing 6-year-olds (N = 25) with these materials. Thus far, children’s performance collapsed across conditions is similar to adults (60%). However, visual information may impact children's performance less.
Acoustical cues versus top-down bias in infants’ parsing
Authors: Babineau Mireille , Shi Rushen
Published: May 2013

French liaison involves the surfacing of an underlying consonant as the onset of the following vowel-initial word (e.g., les amis - /le/ /zami /), creating misalignment. However, acoustic cues that support vowel-initial parsing may exist. We tested French-learning 30-month-olds using a preferential looking procedure. Familiarization stimuli in experiment 1 were sentences each containing a determiner preceding a vowel-initial non-word (e.g., ces onches). Infants’ parsing of the non-word was assessed. The vowel-initial condition presented the vowel-initial non-word versus another non-target (onches - èque). The syllabic condition tested the consonant-initial parse (zonches - zèque). Infants in the vowel-initial, but not the syllabic condition, showed discrimination (p = 0.008), i.e., they correctly parsed the vowel-initial target, possibly using acoustic cues. However, knowledge of underlying liaison consonants can also explain these results. In experiment 2, we removed acoustic cues to vowel-initial parsing by using a consonant-initial non-word following a determiner as the familiarization stimuli (e.g., un zonches). Infants were tested with the same two conditions as in experiment 1. Infants yielded the same results as in experiment 1, showing discrimination only in the vowel-initial condition (p = 0.047). Taken together, 30-month-olds perceived /z/ as an underlying floating element; they used this liaison knowledge, rather than possible acoustical cues, for parsing.
Effect of talker sex on infants’ detection of spondee words in a two-talker or a speech-shaped noise masker
Authors: Leibold Lori , Taylor Crystal , Hillock-Dunn Andrea , Buss Emily
Published: May 2013

Speech recognition performance in the presence of competing speech is typically better for adults when the target and masker talkers are different sexes than when the target and masker talkers are the same sex. One explanation for this result is that the acoustic differences between male and female speech productions promote segregation of the two streams of speech, thus leading to a reduction in informational masking. In this study, an observer-based psychophysical procedure was used to compare infants’ (7–13 months) masked speech detection thresholds for spondee words produced by a male or a female talker in either a two-female-talker or a speech-shaped noise masker. Infants were assigned to a single testing condition. Maskers were presented continuously throughout testing at an overall level of 50 dB SPL, fixed throughout testing. Following training to an 80%-correct criterion, thresholds for the target word were measured adaptively using a 2-down, 1-up procedure. Infants’ thresholds in the two-female-talker masker were higher for the female compared to the male target word. In contrast, infants’ thresholds were similar for the female and male target words in the speech-shaped noise masker. These results suggest that introducing a different sex between the target and masker aids in the segregation of sounds for infants, as has previously been shown for adults. [Work supported by the NIH.]
Preliminary comparison of second-formant discrimination thresholds in cochlear implant users and young normal-hearing listeners
Authors: Rogers Catherine L. , Donaldson Gail S. , Cooley Amanda J. , Russell Benjamin A.
Published: May 2013

Formant discrimination thresholds (FDTs) may provide insights regarding factors limiting vowel perception by cochlear implant (CI) users, but have not been systematically studied in this population. In the present study, estimates of second-formant (F2) FDTs obtained in three CI users were compared to FDTs obtained from three young normal-hearing (YNH) listeners. Procedures and stimuli were modeled after Kewley-Port and Watson [J. Acoust. Soc. Am. 95, 485–496 (1994)] but employed fewer trials and an expanded F2 frequency range. Stimuli were formant-synthesized versions of three target vowels. FDTs were estimated using an adaptive 3AFC task with feedback and based on six consecutive 80-trial stimulus blocks. FDTs for the three YNH listeners were comparable to previously reported FDTs (2.4% of reference frequency versus 1.5% in Kewley-Port and Watson). FDTs for two of the CI users were about 70% larger than the average for the YNH listeners. FDTs for the third CI user approached YNH average values in one frequency region but were enlarged in another region. Data for this CI user could not be explained by place-pitch thresholds (obtained in a previous study) and suggest that CI users’ spectral acuity for complex stimuli may not be directly predictable from measures of spectral acuity for simple stimuli.
What is the default behavior in accommodation: Convergence or maintenance?
Authors: MacLeod Bethany
Published: May 2013

This study, a secondary analysis of data from a phonetic accommodation study, considers the default behavior of speakers in accommodating to another speaker in an interaction. Should convergence or maintenance be considered the default behavior? There is inherent acoustic variation in our speech. Every time we produce a sound, such as a voiceless stop in English, it varies along some phonetic dimension, such as voice onset time (VOT). We might expect that, in the absence of any external influence, these voiceless stops will be realized with VOT longer than their overall mean 50% of the time and with VOT shorter than their overall mean 50% of the time. During interaction with another person, however, studies in social-psychology have suggested that lack of adjustment (maintenance) may be akin to divergence [Tong et al. (1999)]. In addition, convergence is a fairly robust finding in studies of accommodation and imitation [e.g., Nielsen (2011), Babel (2012)], suggesting that perhaps the default behavior in interaction is convergence. The purpose of this talk is to introduce these points of view, discuss the factors that may affect our interpretation, and facilitate discussion on this issue, which has implications for the growing body of research investigating accommodation.
Phonetic accommodation in Spanish-English and Korean-English bilinguals
Authors: Tobin Stephen
Published: May 2013

Preliminary results from eight participants in a cross-linguistic investigation of phonetic accommodation in speech production and perception are presented. The finding that synchronous actions are more stable than asynchronous ones has been reported in studies of general [Kelso (1981)] and speech-specific [Browman and Goldstein (1992), Byrd et al. (2009)] motor control. With reference to glottal-oral timing, near-zero VOTs (voice onset times) are representative of near-synchronous timing, whereas long-lag VOTs are representative of asynchronous timing [Sawashima and Hirose (1980), Dixit (1984), Lofqvist and Yoshioka (1989), Fuchs (2005)]. These observations served as a basis for the prediction that native speakers of Korean, with its long-lag aspirated stops (~120 ms), would more readily accommodate to typical English voiceless stop VOT (~70 ms) than native speakers of Spanish, with its short-lag voiceless stops (~20 ms). Spanish-English and Korean-English bilinguals were recorded reading voiceless stop-initial English words, before and during a task in which participants shadowed recorded productions of a native speaker of American English. Preliminary analysis of the production data provides some support for these hypotheses. The results contribute to our understanding of the conditions that promote phonetic accommodation.
Is the mora rhythm of Japanese more strongly observed in infant-directed speech than in adult-directed speech?
Authors: Tajima Keiichi , Tanaka Kuniyoshi , Martin Andrew , Mazuka Reiko
Published: May 2013

Japanese has traditionally been called “mora-timed,” but studies have shown that this intuition is based not on durational tendencies but rather on phonological, structural factors in the language. Meanwhile, infant-directed speech (IDS) is said to “exaggerate” certain properties of adult-directed speech (ADS), including rhythm. If so, then it is possible that the mora rhythm of Japanese is more strongly observed in IDS than ADS. To investigate this possibility, the present study utilized the RIKEN Japanese Mother-Infant Conversation Corpus, which contains approximately 11 h of IDS by 22 mothers talking with their 18-to-24-month-old infants, and 3 h of ADS by the same mothers. Results from durational analyses showed that aspects of mora rhythm, such as the distinction between phonemically short and long vowels and singleton and geminate consonants, and the tendency toward isochrony of moras, were not greater in IDS than ADS. Mora duration in IDS was instead more variable, partly stemming from greater phrase-final lengthening and non-phonemic, emphatic lengthening. Results from structural analysis, however, showed that non-CV moras such as moraic nasals that characterize Japanese rhythm occurred more frequently in IDS than ADS. These results suggest that even in IDS, Japanese rhythm is manifested structurally, not durationally. [Work supported by JSPS.]
Pitch affects voice onset time: A cross-linguistic study
Authors: Narayan Chandan , Bowden Mary
Published: May 2013

Recent research into the acoustics of infant-directed speech (IDS) in English and Korean suggests that voice-onset time (normalized for varying speech rate) in word-initial aspirated stops are shorter than in adult-directed speech. The present study reports results from experiments conducted to explore the source of this VOT variation in IDS. Female English speakers (n = 10) and female Korean speakers (n = 10) recorded sentences with words varying in laryngeal condition (English: voiced/voiceless; Korean: plain, tense, aspirated) at three different pitches (low, normal, and falsetto). Results suggest that as speakers’ pitch increases, the duration of VOT in aspirated stops decreases. Voiced stops (in English) and plain and tense stops) in Korean showed no difference in VOT across varying pitch conditions. Regression models suggest that VOT becomes less predictive of laryngeal state as speaker pitch increases. Results are discussed in terms of the physiological explanation of the pitch-VOT effect as well as the implications for the development of sound systems in infants.
/oy/ as a marker of local identity in Berlin
Authors: Jannedy Stefanie , Wierich Melanie
Published: May 2013

A fairly recent observation of multi-cultural urban German speech as spoken in Berlin is that the diphthongs /oy/ and /ey/ are realized more closed and fronted compared to more standard varieties of German. For this pilot study, spontaneous speech data were collected through standardized interviews from five young female speakers from two different neighborhoods in Berlin: Wedding is more Arab-dominant while Kreuzberg is more Turkish dominant. Their speech was orthographically transcribed and added to a database that allows for searching for all occurrences of the two diphthongs under investigation in their naturally occurring context in unscripted speech. So far, 250 occurrences of these vowels have been analyzed. Formant measurements were taken at five equally distanced points throughout the diphthong. A linear mixed effects model with the midpoint of the F2-formant value as the dependent variable were run, showing that speakers from the arab neighborhood (Wedding) significantly differ in their productions compared to speakers from the Turkish neighborhood (p < 0.05) in Kreuzberg. Moreover, there was a significant effect of language spoken around them (p < 0.01) on the production even though German is their dominant language. We argue that speakers use the production of these diphthongs as markers of their local urban identity.
Analysis of pre-echo artifact in generating a focused source
Authors: Song Min-Ho , Choi Jung-Woo , Kim Yang-Hann
Published: May 2013

A focused source is a virtual source that can provide an auditory illusion of sound radiating between the loudspeaker array and listener. When generating a focused source, a listener cannot avoid undesired pre-arriving direct waves from the control sources, which is known as pre-echo artifact. Investigation of the artifact can be seen in several researches; however, no mathematical definition of the pre-echo artifact is given so far and only the observation in limited case is known with computer simulation. The objective of this paper is to observe the cause and effect of pre-echo artifact analytically. The paper defines the pre-echo artifact mathematically, and the artifact at the arbitrary listening position is formulated with integral form based on Kirchhoff-Helmholtz integral equation. From the definition of the pre-echo, it is shown that the convergent wave of a focused source can be regarded as a special case of a pre-echo artifact. Furthermore, the derivation shows that the pre-echo artifact occurs in the case of using continuous array and is evolved due to the time-reversed nature of the solution.
Influence of low-order room reflections on sound zone system performance
Authors: Olik Marek , Jackson Philip , Coleman Philip , Olsen Martin , Mo/ller Martin , Bech So/ren
Published: May 2013

Studies on sound field control methods able to create independent listening zones in a single acoustic space have recently been undertaken due to the potential of such methods for various practical applications, such as individual audio streams in home entertainment. Existing solutions to the problem have shown to be effective in creating high and low sound energy regions under anechoic conditions. Although some case studies in a reflective environment can also be found, the capabilities of sound zoning methods in rooms have not been fully explored. In this paper, the influence of low-order (early) reflections on the performance of key sound zone techniques is examined. Analytic considerations for small-scale systems reveal strong dependence of performance on parameters such as source positioning with respect to zone locations and room surfaces, as well as the parameters of the receiver configuration. These dependencies are further investigated through numerical simulation to determine system configurations which maximize the performance in terms of acoustic contrast and array control effort. The design rules for source and receiver positioning are suggested, for improved performance under a given set of constraints such as a number of available sources, zone locations, and the direction of the dominant reflection.