bluuebunny/crossref_metadata_2025 huggingface dataset:
Moving fluid loading to the basilar membrane in passive nonlinear cochlear model.
Authors: Kovinskaya Svetlana
Published: March 2010

The mechanical response of the cochlea to sound is a nonlinear phenomenon. Existing models (with either passive or active outer hair cells) do not include effect of the motion of fluid loading to basilar membrane (BM). Being extremely slow this motion will play significant role only if the traveling wave in BM is close to the point of ceasing of propagation. Two fluid channels corresponding to the scalae vestibuli and tympani, each filled with incompressible liquid, provide the fluid loading to BM. Equation describing BM vibration with contra-directed moving fluid loading (from opposite sides of BM) becomes nonlinear equation because of an additional force proportional to loading velocity squared and the local curvature of BM (the second derivative of BM displacement). The velocity of this mass-like fluid motion is proportional to the applied sound power. In the case of sinusoidal excitation, the equation for BM vibration becomes the Mathieus equation with the characteristic equation determining stable and (parametrically) unstable regions. The nonlinear equation gives a multi-frequency quasi-steady state solution. Suggested mechanism (additional forces in the equation for BM vibration) explains the compression of strong stimuli, explains the generation of distortion products, and is in qualitative agreement with other experiments.
Predicting the effects of compression incorporating signal-adaptive band allocation.
Authors: Kates James M.
Published: March 2010

This paper considers the effects of dynamic-range compression on speech intelligibility and quality for hearing-impaired listeners. The paper focuses on a modification of compression in which the compression behavior for each frequency band is controlled by the peak amplitude within a frequency region surrounding the band. The stimuli are sentences in a background of multi-talker babble. Speech intelligibility and quality indices are used to model the listener responses for mild, moderate sloping, and moderate/severe hearing losses. The indices predict the effects of varying the compression parameters and the width of the frequency region, thus giving an indication of the expected benefit of the modified compression system and the optimal parameter settings as a function of hearing loss and listening conditions.
Modeling quality judgments of music stimuli reproduced by a simulated hearing aid.
Authors: Kates James M. , Arehart Kathryn H.
Published: March 2010

The focus in hearing aids is generally on speech, but the ability to reproduce music is also important for listener satisfaction. This study uses a sound quality metric to predict judgments of music quality made by normal-hearing and hearing-impaired listeners. A simulated hearing aid was used to process music modified by (1) additive noise and nonlinear processing, (2) linear filtering, and (3) combinations of noise, nonlinear processing, and linear filtering. The music stimuli included jazz, classical, and vocalize selections. The quality metric incorporates a model of the auditory periphery that reproduces aspects of impaired hearing. The effects of noise and distortion on the signal are estimated by measuring the changes to the envelope time-frequency modulation pattern, and the effects of linear filtering are estimated by measuring the changes to the signal long-term internal spectral representation. The accuracy of the quality metric for music will be presented, and the performance of the metric for music will be compared to its accuracy in reproducing the quality ratings of speech stimuli processed under similar conditions.
Finite element vibration analysis and measurement of a 255 ft vehicle ferry.
Authors: Spence Jesse H. , Dempsey Ron E.
Published: March 2010

Finite element analysis (FEA) methods have become part of the standard repertoire when designing a ship. This is particularly true for static analyses, although FEA methods are becoming increasingly utilized for analysis of low-frequency vibration as well. This paper discusses the FEA modeling process that was used for analyzing low-frequency (less than 80 Hz) habitability vibration on a 255 ft vehicle ferry. Deck vibration levels were measured after the vessel was built. Measured versus predicted vibration data show good correlation, particularly when the various sources of potential error and uncertainty are considered. The subject ferry was designed to meet the ABS Comfort Class (COMF) vibration criteria. Calculations of deck vibration were performed using NEiNastran to verify compliance with the criteria. Excitations due to propeller hull pressure excitation are highlighted here as these forces created the largest deck responses. However, it is noted that the main propulsion engines were resiliently mounted subsequent to initial analyses using the FE model. This paper discusses pertinent details of the model (element types, properties, etc.), application of hull pressures, damping, analysis methodology, and interpretation of results. Areas of uncertainty and impacts to the results are discussed.
An evaluation of residual vectors in the commercial finite-element program NASTRAN.
Authors: Fahnline John B.
Published: March 2010

MSC NASTRAN introduced residual vectors in 2005. They are used to improve solution accuracy by representing the static contributions of truncated modes in transient and frequency response calculations. This formulation is convenient because the residual vectors are added to the modal vectors to form an augmented basis set, where the residual vectors are orthogonal to each other and to the original mode set. Modal frequency response calculations then proceed as usual only with a few extra vectors in the basis set. This talk will focus on evaluating the improvements in accuracy that can be achieved using residual vectors for modal frequency response problems where two structures with truncated mode sets are joined together.
Engaging structural-acoustic simulations in multi-discipline design.
Authors: Vlahopoulos Nickolas , He Jim
Published: March 2010

In order to be effective and maximize the weight and cost savings, designing for noise and vibration attributes must be performed in parallel when designing a complex system for other disciplines (i.e., durability, crashworthiness, etc.). The system characteristics influence the performance in all the different attributes. Challenges arise when designing a system for improving mutually competing objectives, satisfying constraints from multiple engineering disciplines, and determining a single set of values for the vehicle characteristics. This presentation discusses an approach that conducts optimization analysis for a complex system by coordinating operations and exchange of data and information through a network of optimizations. A rotorcraft application is analyzed for structural-acoustic and crashworthiness. The hybrid finite element analysis (hybrid FEA) comprises the simulation method used for the structural-acoustic simulation. It combines conventional FEA with energy FEA for modeling the response of a system comprised by stiff, load bearing members, and flexible panels. The LS-DYNA solver is used for the crash-landing simulations. The weight of the gear box foundation is optimized while simultaneous improvements are pursued through parallel driven optimizations that address the input power into the system from gearbox excitation and the dynamic stresses encountered in the gearbox foundation from crash landing.
A procedure for estimating gestural scores from articulatory data.
Authors: Nam Hosung , Mitra Vikramjit , Tiede Mark K. , Saltzman Elliot , Goldstein Louis , Espy-Wilson Carol , Hasegawa-Johnson Mark
Published: March 2010

Speech can be represented as a set of discrete vocal tract constriction gestures (gestural score) defined at functionally distinct speech organs [tract variables (TVs)]. Using such gestures as sub-word units in an ASR system, variation in speech arising from coarticulation and reduction can be addressed. Since there is a lack of test corpora annotated with gestural scores, we develop a semi-automatic procedure for estimating and annotating gestural scores from natural speech databases using the Haskins speech production model (TaDA). We first describe the procedure’s application to 500 words with unique phone sets found in the Wisconsin x-ray microbeam database, generating both gestural scores and synthetic speech. Second, we perform dynamic time warping (DTW) to align the TaDA-generated speech signals with respect to the microbeam data. The DTW time-scaling pattern is then used to adjust the gestural score originally input to TaDA to generate new time-warped TaDA acoustics. Third, we fine-tune the gestural timing patterns within the new gestural score in a constrained manner to generate the score whose associated acoustics are minimally different from the database acoustics. Finally, we evaluate the optimized gestural score’s validity by comparing its associated TV trajectories to those from the original microbeam database.
Prosodic interaction between speakers of American and British English.
Authors: Krivokapic Jelena
Published: March 2010

Previous work has found that interaction between speakers influences their production, in that phonetic similarity of the speakers to each other increases [Sancier and Fowler, J. Phonetics 25, 421–426 (1995); Pardo, J. Acoust. Soc. Am. 119, 2382–2393 (2006); and Tobin, J. Acoust. Soc. Am. 125, 2757 (2009)]. These studies have mostly focused on segmental properties of speech. Little is known, however, about how prosodic properties of speech are affected in conversational interaction. An experiment is presented that examines the interaction between native speakers of British English and American English. Using the synchronous speech paradigm [Cummins, ARLO 3, 7–11 (2002) and Zvonik and Cummins, in Proceedings of the Eurospeech 2003 (2003), pp. 777–780] where two speakers read sentences at the same time, we examine how speakers influence each other at the prosodic level. Eight subjects (4 dyads), each consisting of one British and one American speaker, read the following: a short story that contained four words where the two dialects differ in stress pattern, 13 target words where the dialects differ in vowels, and 84 sentences with varying intonation patterns (question, statement, and focus). The goal was to examine how speakers adjust to each other’s speech, and whether certain prosodic properties are more susceptible to adjustment to the co-speaker’s production than others.
Prosodic boundaries in German: Final lengthening in spontaneous speech.
Authors: Fuchs Susanne , Krivokapic Jelena , Jannedy Stefanie
Published: March 2010

Most theories of prosodic structure postulate at least two phrasal categories above the word level, a minor and a major one. One correlate of phrasal boundary marking is lengthening on the right edge of a phrase. To gain a theory neutral understanding of the nature of prosodic boundaries, a Gaussian mixed model (GMM) was applied to durational data, estimating the underlying clusters of a continuous distribution. Spontaneous speech data were collected with standardized interviews from 19 adolescent speakers of a multi-ethnolect (Kiezdeutsch, Hood German) spoken in Berlin, orthographically transcribed and added to a database that allowed for searches of the particle “so”(so or like) in different conditions. Acoustic durations of /z/ and /o/ of so in phrase final position (as determined by orthographical markings or by following pauses) were labeled and z-transformed per speaker. The results show that a model including two clusters accounts best for the data. Nevertheless, there is an overlap between the two distributions supporting the gradient nature of boundaries. Further analyses with more tokens of so including word level junctures are currently under way. The impact of our data-driven results on theoretical models of prosodic boundaries is discussed. [Supported by a grant from BMBF.]
Prosodic analysis of subglottal pressure contours.
Authors: Hanson Helen M , Shattuck-Hufnagel Stefanie , McLelland Angela
Published: March 2010

In previous work the problems of identifying final fall and estimating declination of the subglottal pressure contour were addressed [Hanson et al., J. Acoust. Soc. Am. 118, 2027 (2005); 120, 3090 (2006)]. Additional methods for identifying final fall have since been explored. These new methods will be described, and the identification of final fall will be compared across several of the methods. The use of these additional methods has meant that the complete data set for three subjects can be analyzed. Therefore it is worth revisiting the work presented in 2006. Objective measures of subglottal pressure declination will be evaluated with respect to subjective ratings of declination. The effects of phrase and boundary tones on declination rate will be re-examined, as will the effects of pitch accent distribution. [Work supported by NIH Grants DC00075 and DC04331 and by a Union College summer research grant to A.M.]
Temporal structure in the speech of persons with dementia: A preliminary study.
Authors: Carozza Linda , Quinn Margaret , Palladino Jacqueline , Bell-Berti Fredericka
Published: March 2010

Although cognitive and language processes in dementia have been studied extensively, the question of motor speech degeneration in the course of dementing illness is a relatively unexplored area. The potential for early dissociation of motor functions of language at the level of speech production has not been explored; an interaction between motor speech and language production and perception changes should inform our understanding of the deterioration in dementia. If early motor declines are found, they may provide an additional early marker and contribute to early detection, giving further insight to the character of neurological deterioration in this disease. This study explores the temporal structure of speech in individuals in the mild-to-moderate stages of the disease. In this preliminary study, participants were asked to produce a series of four-word phrases containing target word in phrase-medial or phrase final position. The target words contained the vowel in “heed,” “head,” or “had,” and began with a fricative or voiced or voiceless stop consonant and ended with either /t/ or /d/. Thus, we are able to examine four aspects of the temporal patterns of speech in these persons: intrinsic vowel duration, VOT, phrase-final lengthening, and the effect of final consonant voicing on vowel duration.
Modifying speech to children based on perceived developmental level: An acoustic study of adults’ fricatives.
Authors: Julien Hannah M. , Munson Benjamin , Edwards Jan , Beckman Mary E. , Holliday Jeffrey J.
Published: March 2010

Recent acoustic studies have shown that children learning English gradually differentiate between the sounds /s/ and /∫/ [Li et al. (2009)]. Other studies have shown that adults can perceive different degrees of accuracy in these phonemes when given a non-categorical response modality, such as a visual-analog scale [Urberg-Carlson et al. (2008)]. This presentation combines a VAS rating task with a production task. Adults were presented with children’s productions of target fricatives. They rated the accuracy, after which they were instructed to produce the target sequence as if they were responding to the child whose speech they had just rated. Ongoing analyses examine whether adults respond differently to productions that they have rated as intermediate between /s/ and /∫/ and whether adults produce hyperarticulated version of fricatives in response to productions that they rated as not canonically /s/ or /∫/ , as opposed to ones that they rated as adult-like. The results of this project will be used in supervised learning models of the acquisition of /s/ and /∫/ and will inform us on the extent to which adults calibrate their speech to children depending on the perceived level of speech mastery. [Work supported by NIDCD Grant 02932 and NSF Grant BCS0729277.]
Palatalization in infant-directed speech.
Authors: McCammon Jenesia , Bernstein Ratner Nan
Published: March 2010

Adult-directed speech (ADS) is characterized by frequent use of phonological rules such as palatalization (“did you” becomes “didju”). Use of such rules should blur word boundaries, making it more difficult for infants to identify words in the input. To date, there are conflicting data on the degree to which infant-directed speech (IDS) makes more or less frequent use of these rules [Shockey and Bond (1980) and Bernstein Ratner (1986)]. We are following a cohort of children from 7 months to 2 years. We examined whether rules such as palatalization are used more or less frequently in IDS by 20 mothers to their children and to an adult listener. To date, there are more opportunities for palatalization in the mothers’ IDS than ADS to pre-verbal children, and the rule is more frequently applied in IDS. In this case, IDS is not more acoustically clarified than ADS. Research suggests that IDS clarification may be a function of the child’s language stage. We would therefore not expect reduction in palatalization, which primarily affects functors, until a later stage of the child’s language development.
Voice onset time in infant-directed speech at 7.5 and 11 months.
Authors: Synnestvedt Anna , Bernstein Ratner Nan , Newman Rochelle
Published: March 2010

Studies have reported differences between infant-directed speech (IDS) and adult-directed speech (ADS), suggesting that mothers adjust speech to their infants in ways that may help children better parse the incoming acoustical signal. One aspect of IDS that has been examined is voice onset time (VOT). Results have been inconsistent, revealing longer VOT in IDS [Englund (2005); Malsheen (1980)], shorter VOT in IDS [Sundberg & Lacerda (1999)], or no difference in VOT between ADS and IDS [Baran et al. (1977)]. Characteristics of IDS may also depend on the language maturity of the child and, therefore, clarity of speech may vary across stages of development [Englund & Behne (2006)] as well as vary among mothers. The present study examines 15 mothers’ VOT in IDS to children at 7.5 months old and again at 11 months as compared to their VOT in ADS. Words with initial stop consonants that occurred in both IDS and ADS conditions are analyzed using PRAAT. Variability was observed among mothers and age effects: preliminary data suggest that VOT in IDS at 11 months is better differentiated than at 7.5 months. [Work supported by NSF BCS0745412.]
Phonetic adaptation in non-native speech: Insights from a distributional analysis of long-lag voice onset time.
Authors: Pineda Marisa , Sumner Meghan
Published: March 2010

Speakers encountering long-lag voice onset time (VOT) for the first time in their L2 produce VOTs between their L1 and L2 values. Native-like long-lag productions are conditioned by speaker competency factors such as age of acquisition and experience, showing significant production differences between late bilinguals, early bilinguals, and native L2 speakers. Thus far, analyses have focused on average VOTs across speaker groups. This project investigates the full distributional properties of VOT in bilinguals (e.g., variation and skewness) in addition to averages, providing a more informative picture of bilingual acquisition. VOT production data were collected from French-English bilinguals (age of English onset 0–15 years) and submitted to a distribution-based analysis. Results show that while speaker groups differ predictably in mean VOT, the analysis discovers subgroups based on common production behaviors, eliminating the gross categorizations of early and late bilinguals and moving toward gradual, predictable shapes of VOT that are correlated with English schooling, time in an English-speaking country, and age of acquisition. Ultimately, these results may fill in some missing blanks between perception and production, suggesting, for example, that differences in perceived accent and comprehensibility diverge due to degree of overlap with native L2 VOTs.
A Bayesian model of voice-onset time production.
Authors: VanDam Mark , Silbert Noah
Published: March 2010

Talkers performed a listen-and-repeat task to investigate temporal detail in voice-onset time (VOT) productions of American English word-initial stop consonants. Experimental factors included linguistic context (isolation, carrier phrase, unfamiliar phrase, and familiar phrase), usage frequency (high and low), lexical status (word and non-word), training (baseline and posttraining), and posttraining generalization (test words and novel words). For each context, frequency, and lexical status, baseline VOT production estimates were collected, then a naive training regimen conducted, then posttraining estimates of both test words and novel words were obtained. Testing novel words explored whether the effect, if obtained, generalized throughout the lexicon. A Bayesian linear model (analogous to analysis of variance) was used to model VOT means as a function of these factors. Posterior distributions of modeled VOT means were compared across six talkers, with a focus on probing the relationships between lexical frequency and status, linguistic context, and training. Preliminary results suggest that a number of these experimental factors influence fine-grained control of VOT production. As expected from speech production data obtained from multiple talkers and thousands of productions, the overall model fit was imperfect, but the results indicate that a Bayesian model can be productively deployed for data exploration into temporal aspects of speech production.
Why are Korean tense stops mastered early: Evidence from production and perception.
Authors: Kong Eun Jong , Beckman Mary E.
Published: March 2010

Transcription-based studies have found that Korean-acquiring children master tense stops earliest among the three different types of homorganic stops (tense vs lax vs aspirated) despite its phonologically marked status. Tense stops in Korean have a short-lag VOT, so this finding is consistent with previous cross-linguistic research on order of acquisition of stop phonation types. However, Korean tense, lax, and aspirated stops are also differentiated by the fundamental frequency and the voice quality at the vocalic onset in addition to VOT. This study examined how correctly these multiple acoustic cues (VOT, f0, and H1-H2) predict the mastery pattern of Korean stops. The effect of these acoustic parameters on 20 Korean adult listeners’ assessments of children’s (aged 2–6) productions of /t′/, /t/, and /th/ was analyzed. Listeners were asked to label the stimuli as one of three stop categories and then to rate their goodness using visual analog scaling. Both categorical and gradient assessments of children’s stops were analyzed based on the three acoustic parameters in a mixed-effect regression model in order to quantify the relative effects of acoustic parameters on adult perception of phonation. [Work supported by NIDCD 02932 and NSF Grant 0729140.]
Functional anatomy of the human tongue: Review and implications for the development of speech production.
Authors: Denny Margaret , McGowan Richard S.
Published: March 2010

To acquire speech children must attempt to reproduce adult acoustic models using immature vocal tracts which differ from those of adults in complex ways. Control of the tongue is crucial for acceptable speech, yet the tongue is an understudied articulator because it is anatomically complex and difficult to record from using kinematic or electrophysiological methods. Nevertheless recent advances in tongue anatomy and physiology, combined with knowledge of vocal tract development, promise to shed light on the problems that children must solve in learning to speak as well as the solutions available to them. This review aims to integrate and present these findings to an audience interested in the development of speech production. A striking finding is that the tongue shows an anterior-to-posterior gradient in muscle fiber sizes and types. In multiple muscles, faster fibers are more common anteriorly while slower fibers are more predominant in the posterior tongue. Within fiber type (fast or slow) smaller fibers are seen anteriorly and larger ones posteriorly. This implies that rapid fine positioning and shaping may be particularly challenging when it involves the posterior tongue. [Work supported by NIDCD-0001247 to CReSS LLC.]
Tracking muscle deformation during speech from tagged and diffusion tensor magnetic resonance imaging.
Authors: Liu Xiaofeng , Ramenahalli Sudarshan , Shinagawa Hideo , Stone Maureen , Prince Jerry L. , Murano Emi Z. , Zhuo Jiachen , Gullapalli Rao
Published: March 2010

Oral head and neck cancer is the sixth most common cancer worldwide. These tumors are usually treated by surgical removal of the affected tissue. The result of the surgery is a loss of muscle tissue, accompanied by scarring, reduced strength, and often reduced function. This paper explores the relationship between tongue muscle orientation and muscle deformation pattern in normal and post-cancer surgery speakers. Our motivation is the need to better understand the mechanisms that underlie tongue motion, in order to better interpret clinical observations and to provide data that can help predict optimal surgical outcomes. This study uses diffusion tensor imaging (DTI) to extract muscle fiber orientation, but it is not possible to image the muscle deformation in real-time using DTI. On the other hand, tagged MRI can track muscle fiber bundles in real time, but the original fiber bundle is not visible. Therefore, this work develops a method to overlay muscle bundles from the DTI onto the corresponding locations in tagged MR images and track muscle deformation. The mechanical properties of the muscles are calculated, such as translation and bending. Motion pattern differences between the normal and glossectomy tongue are detailed. [NIH R01-CA133015 and K99-DC9279.]
Can an ultrasound tongue be overlaid on an MRI (magnetic resonance imaging) vocal tract?
Authors: Lee Jim , Stone Maureen
Published: March 2010

Ultrasound image sequences and cine-MRI time-frames provide intersecting but not identical data about the articulation of speech. It would be valuable to be able to combine ultrasound and MRI datasets in a way that maximizes their strengths. Midsagittal MRI images the entire vocal tract; ultrasound images the tongue surface. However, MRI is not portable, requires multiple repetitions, and supine subject positioning. Thus insertion of the tongue from ultrasound movies onto the MRI vocal tract would provide tongue motion in a head coordinate system. This study aligns supine ultrasound tongue contours with MRI tongue contours of the same tasks using (1) rigid alignment of the tongue contours frame-by-frame and (2) rigid alignment of palates, whose alignment parameters are then applied to tongue contours. rms differences compare the error between methods. The value of this study is that if palatal alignment yields a comparable error to tongue alignment, then palatal alignment could be used to insert an ultrasound data set into a vocal tract outline that has no tongue motion data associated with it. [Funding support: R01CA133015.]
An articulatory, acoustic, and perceptual study of the effect of a short lingual frenulum on flaps in late Korean-English bilinguals.
Authors: Kim Kyung-Ah
Published: March 2010

Having a short lingual frenulum is known to limit tongue mobility, often resulting in nonstandard pronunciations of certain coronal sounds. While previous studies have largely focused on the physical and linguistic characteristics of the most extreme cases and on the effects of surgical intervention [Hagiwara et al. (2002); Lee et al. (2008)], the current study investigates the articulatory, acoustic, and perceptual characteristics associated with Korean speakers with a relatively short lingual frenulum but not short enough to greatly impede communication. The study focuses on the flap—the single most problematic sound for Korean speakers with short lingual frenula—produced in both Korean and English by both “short-tongued” and normal late Korean-English bilinguals. Flaps are studied through palatographic, linguographic, and spectrographic analyses, while a perception test is performed to pinpoint the categorical boundary between the normal and short-tongued flaps. Preliminary results suggest that the short-tongued speakers are better able to accurately produce the English flap than the Korean flap, due to language-specific phonetic and phonological characteristics. This finding bears on whether surgical intervention is necessary to help normal (and mildly short-tongued) speakers of Korean improve their English pronunciation [se Ko (unpublished)].
Resonance-based source-filter separation for speech.
Authors: Selesnick Ivan , Tan Chin-Tuan
Published: March 2010

This paper proposes the application of resonance-based signal analysis to the decomposition of speech into “source” and “filter” waveform components. Resonance-based signal analysis, developed by Selesnick,1 is a novel analysis method that decomposes a signal into high-resonance (oscillatory) and low-resonance (transient) components. The original signal is given as a sum of the two components. The method utilizes sparse signal representations in the domain of two invertible constant-Q transforms, having low- and high-Q-factors, respectively. The constant-Q transforms are implemented as rational-dilation wavelet transforms. Applied to speech, the method provides a separation that cannot be achieved with other known filtering techniques. Current source-filter modeling of speech assumes a known linear filter which sufficiently estimates vocal tract characteristics and can be derived from a segment of stationary speech. The source glottal waveform is then extracted by inverse filtering. In contrast, resonance-based signal analysis directly decomposes speech into its source and filter waveforms without such assumptions. The outcome may provide a new perspective in speech analysis, synthesis, recognition, and coding. This paper illustrates the efficacy of this signal analysis technique with vowels; further investigation with other speech elements is in progress.
Speech separation based on multi-level segmentation.
Authors: Lopez Jose J. , Cobos Maximo
Published: March 2010

Speech separation is still a challenging issue in acoustic signal processing. To deal with this problem, sparse methods are usually employed when there are more sources than sensors (underdetermined problem). In this paper, a two-microphone separation method is presented. The proposed algorithm is based on grouping time-frequency points with similar direction-of-arrival (DOA) using a multi-level thresholding approach. The thresholds are calculated via the maximization of the interclass variance between DOA estimates and allow to identify angular sections wherein the speakers are located with a strong likelihood. Separation is finally performed by means of time-frequency masks. Several experiments conducted under different mixing scenarios are discussed, showing the benefits of the proposed approach.
Classification of gender based on cepstral coefficients and spectral moments.
Authors: Spinu Laura , Lilley Jason
Published: March 2010

Several gender classification methods based on acoustic information were compared. The data came from 31 native speakers of Romanian (10 males, 21 females). A subset of fricatives and vowels (7348 tokens) was divided by hidden Markov model training into three acoustically uniform regions. For each region, (a) a set of cepstral coefficients, specifically c0–c4 and (b) two sets of spectral moments, specifically bark-transformed and linear moments 1–4 plus rms, were extracted. The acoustic data were then used in a linear discriminant analysis to classify the tokens by gender. The findings show that cepstral coefficients perform better than spectral moments in gender classification, and that spectral moments are more successful than linear moments. The overall correct classification was 90% for the cepstral analysis, 78% for bark spectral moments, and 72% for linear moments. When the data from fricatives and vowels were examined separately, it was found that in all cases the vowel information yielded more accurate gender classification (e.g., 84% correct classification for cepstral moments based on vowels only), but the fricative information alone could account for 78% correct classification. These analyses provide insight into the differential distribution of acoustic features related to gender over segment types.
Modulated helicity for acoustic communications and helicity-selective acoustic receivers.
Authors: Marston Timothy M. , Marston Philip L.
Published: March 2010

Helicoidal or vortex beams have an azimuthal phase gradient and an axial null in amplitude. The sign and magnitude of the azimuthal phase gradient determine the helicity and topological charge of the beam and the associated handedness. Beams with a unit-magnitude charge have been generated with a four-sector array, adjacent quadrants being driven with a 90 deg phase offset [B. T. Hefner and P. L. Marston, J. Acoust. Soc. Am. 106, 3313–3316 (1999)]. The present work shows that the helicity can be rapidly modulated with an appropriately timed reversal of the excitation to a single pair of diagonal sectors. This reversal was demonstrated with an electronic commutator that inverts (at a zero crossing of the sine-wave excitation) two of the channels prior to amplification. While the wave helicity may be inferred with processed signals from a detection array, it may also detected with simple superposition of outputs from a four-element detector using appropriately offset elements. Digital communications was demonstrated where signals of the wrong helicity were suppressed. Scattering by symmetric objects on the axis of the beam preserves the helicity of the radiation [P. L. Marston, J. Acoust. Soc. Am. 124, 2905–2910 (2008)]. [Work partially supported by ONR.]
Amplitude, phase, location, and orientation calibration of an acoustic vector sensor array. Part II. Experiments.
Authors: Basten Tom
Published: March 2010

An acoustic vector sensor array consists of multiple sound pressure microphones and particle velocity sensors. A pressure microphone usually has an omni-directional response, yet a particle velocity sensor is directional and usually has a response pattern as a figure of number eight. Currently, acoustic vector sensor arrays are under investigation for far field source localization and visualization. One of the major practical issues in these applications, however, is to determine the accurate position, orientation, and complex (phase and amplitude) sensitivity of each sensor within the array. In this study, a calibration method, which is discussed in Part I, is verified with experiments. The method determines all the crucial parameters based on a limited number of measurements with a reference sensor and multiple sound sources located at known locations. The calibration method shows also to be robust to mistakenly switched cable connections. The experiments are performed in different acoustic environments including an anechoic room. The results will be presented in this paper.
Experimental study of vector array time reversal communication.
Authors: Wang Zhongkang , Zhang Hongtao , Yang Xiaofan
Published: March 2010

The cooperative array performance experiment (CAPEx) was performed in Lake Washington near Seattle in September 2009 [Rouseff et al., this session]. The experiment included a passive time-reversal communications component. A variety of communications signals in the 1.5–4 kHz band were transmitted including BPSK, QPSK, DSSS, and OFDM. The signals were recorded on an eight-element vertical vector array used as the receiving array at ranges up to 4 km. Results are given by using combined scalar and vector sensors. [Experiment supported by ONR.]
Concerning the null contours of vector sensors.
Authors: Schmidlin Dean J.
Published: March 2010

A common use of a vector sensor is to maximize the sensing of a plane wave coming from one direction while creating a null in regard to a plane wave coming from another direction. It is shown that when this is accomplished, there is a null not only in the desired direction but a whole contour of nulls. The shape of the contour is a function of a single parameter and is described by means of a contour plot in the azimuthal angle–elevation angle plane. Additional insight is found by mapping the contours onto a unit-sphere in the spatial domain. One byproduct of the notion of null contours is a method for selecting the coefficients of the vector sensor for the case of two interfering sources. Finally, it is shown that once the null contour is understood for the vector sensor, it is a simple matter to extend the concept to directional acoustic sensors of higher order.
Acoustical considerations for vocal music rehearsal rooms: A choir director’s perspective.
Authors: Manternach Jeremy
Published: March 2010

What do vocal/choral instructors value in a rehearsal space? Along with logistical considerations, these instructors also desire particular room acoustic conditions. How might their input affect the decisions of architects and acousticians? This question is investigated through examination of several school rehearsal spaces. The study will include acoustical measurements from rehearsal spaces, opinions of vocal music instructors, and feedback from vocalists who rehearse in each space.
Acoustical design of special purpose rooms in schools: Music rooms.
Authors: Siebein Gary W. , Paek Hyun , Jones Chris, P. , Skelton Reece
Published: March 2010

Design strategies for music education rooms in elementary, middle, and high schools based on an impulse response-based theory are presented through a series of case studies of existing, renovated, and designed rooms. The strategies include providing sound reflections to allow the instructor to hear individual groups of students as well as to allow the students to hear each other, controlling room volume and absorption to allow early sound reflections for clear hearing, and simultaneously provide diffuse, low-level running reverberance to enhance musical qualities, providing for clear verbal communication between teacher and students and limiting background and intruding noise levels. The impulse response-based measures are reduced to a series of architectural systems that can be implemented using alternate construction systems to meet budget requirements. Standard design concept sketches communicate the intent of the acoustical design to Architects, School Board members, Design Builders and music faculty.
Modeling of precise onset spike timing for echolocation in the big brown bat, Eptesicus fuscus.
Authors: Gaudette Jason E. , Simmons James A.
Published: March 2010

The neuronal circuits enabling highly accurate sonar performance in bats are not well understood. In this research, a computational neuroscience model was developed based on Meddis’ auditory peripheral model and a biologically plausible network of integrate-and-fire neurons. The stimuli presented to the model include acoustic simulations of target echoes using wideband FM echolocation calls recorded from Eptesicus fuscus. Synaptic connectivity of the neural network was varied to explore its effect on the precision of onset spike timing. Results show that precisely timed spike codes can relay sufficient information of echo time-frequency representations to account for performance observed in laboratory experiments. This research represents a portion of our overarching goal to reverse engineer the bat’s critical auditory functions into a refined sonar signal processing algorithm. A necessary first component of this process is to understand the functionality of relevant circuitry in the auditory midbrain. Such biomimetic processing schemes may be useful in active sonar applications suffering from a high degree of environmental clutter, where man-made systems typically demonstrate poor performance.
Ear deformations in the biosonar system of horseshoe bats.
Authors: Gao Li , He Weikai , Balakrishnan Sreenath , Müller Rolf
Published: March 2010

Many bat species exhibit conspicuous ear movements as part of their biosonar behaviors. The resulting transformations of the pinnae can contain rigid rotations as well as nonrigid deformations. Characteristic ear deformations are frequently observed in horseshoe bats (Rhinolophidae). In these animals, the pinna changes regularly between an upright and a bent configuration. In the bent configuration, the tip of the pinna tilts forward, down, and sideways, changing the curvature of large portions of the ear surface. Entire deformation cycles can be completed in as little as 200 ms. The time-variant geometry of the pinna deformations in the greater horseshoe bat (Rhinolophus ferrumequinum) was captured with a stereo pair of high-speed video cameras. Landmark points were marked on the pinna with dyes that were equally visible in the video frames as in x-ray micro-CT. The CT model was matched to the locations of the landmarks in the deforming ears inferred from stereo reprojection. Numerical predictions were obtained for the acoustic behavior of ear shapes at different phases during the deformation cycle. It was found that the pinna deformations seen in the animals can produce large changes in the directivity patterns. [Work supported by NSFC (Project No. 10774092) and CSC.]
Using active acoustics to assess habitat restoration in a freshwater lake.
Authors: Madden Laura E. , Miksis-Olds Jennifer L.
Published: March 2010

Artificial structures increase bottom complexity in man-made reservoirs and aim to increase fishery production by providing improved refuge, forage, and reproduction habitat. Electrofishing is typically employed to assess the effectiveness of these structures but is limited to shallow water sites. Active acoustic technology is a non-invasive sampling method that is more flexible than electrofishing, as it is operational in both deep and shallow water sites. Active acoustics also provides a continuous data series at one location to obtain high-temporal resolution information. An acoustic water column profiler was deployed for 1 week at each of two sites: (1) a control site with no introduced structure and (2) a treatment site with artificial refuge habitat. Difference in fish abundance, vertical distribution, and diurnal behavior between the two sites was assessed from the volume backscatter time series. Variation in fish activity between the two sites was compared. This work demonstrates the utility of active acoustics in assessing the effectiveness of freshwater habitat alteration beyond the scope of conventional techniques. A more comprehensive evaluation of habitat restoration is crucial in guiding the development of future conservation efforts.
Relative salience of acoustic features in zebra finch song.
Authors: Vernaleo Beth A. , Dooling Robert J. , Leek Marjorie R.
Published: March 2010

Zebra finch song consists of complex acoustic elements repeated over several hundred milliseconds with extreme vocal-motor precision. Much less is known about how song is perceived though previous work has shown that zebra finches easily discriminate between normal and time-reversed versions of song syllables. Here, we used operant conditioning, psychophysical methods, and various synthetic song models to assess the bird’s sensitivity to local versus global temporal changes in song and to determine which cues are most salient in these complex syllables. Birds could discriminate syllable reversals in songs made up of the song envelope filled with noise, suggesting that syllable envelope cues can provide the basis for discrimination. However, birds could also discriminate syllable reversals in songs made up entirely of Schroeder harmonic complexes, stimuli that provide only phase (reversals of fine structure) cues without syllable envelope cues. Birds performed better on longer syllables, suggesting a window of temporal integration for fine structure discrimination. In contrast, humans could perceive few of the syllable reversals within these song modifications. This fine-grained perception in birds suggests that the machinery used for song perception is as precise as the machinery used for song production. [Work supported by NIH.]
Optimization of a 100 MHz fiber optic hydrophone for medical ultrasound applications using nanometer scale gold coating.
Authors: Gopinath Rupa , Manseta Khushali , Nasis Vasileios , Daryoush Afshin S. , El-Sherif Mahmoud , Lewin Peter A.
Published: March 2010

This work describes a novel numerical model developed to optimize the design of a broadband, spatial averaging free fiber optic hydrophone probe (FOHP) for characterization of ultrasound fields in the frequency range 1–100 MHz. The design included minimization of the active sensor dimensions, so its cross-section is comparable with the half acoustic wavelength at the highest frequency of interest and improvement of voltage-to-pressure sensitivity of the probe measured in V/Pa. Initial simulations based on the assumption that bulk refractive index of sputtered material could be used indicated that a thin film gold coating (1–35 nm) could indeed enhance the voltage sensitivity of the FOHP by 16–30 dB; however, a follow up analysis revealed that determination of the coating thickness influence on the FOHP performance would require an introduction of the complex (as opposed to bulk) index of refraction of the sputtered film. The input parameters to the model, their selection criteria, and implementation of the coupled acousto-optic interaction of gold layer will be discussed. The measured prototypes produced unprecedented voltage sensitivity between −234 and −245 dB re 1 V per uPa or 2 and 560 mV/MPa, respectively. [The authors wish to acknowledge support of the NIH R01EB007117 grant.]
Design and implementation of a cylindrical array for passive mapping of cavitation fields produced by clinical high intensity focused ultrasound transducers.
Authors: Faragher Stuart , Gyöngy Miklós , Collin Jamie , Hodnett Mark , Coussios Constantin-C.
Published: March 2010

Key to the success of high-intensity focused ultrasound (HIFU) as a clinical tool is the development of standardized quality assessment procedures to assess the safety and efficacy of HIFU transducers. The present work details the development of a cylindrical sensor array to be positioned around the HIFU focus during pre-treatment quality assessment of clinical transducers, which is designed to localize cavitation activity in three dimensions by passive mapping of the broadband emissions arising from inertial cavitation. The propagation of sound from a collection of broadband sources was first modeled to determine the optimum size, number and distribution of array elements for accurate mapping, and characterization of the cavitation dynamics produced during HIFU exposure. The optimal array configuration was then manufactured from PVDF using a novel printed circuit board technique, and theoretical predictions of the spatial resolution that it could achieve were validated experimentally. Because inertial cavitation is a pressure driven phenomenon, the ability to map cavitation activity using this array could provide a novel tool for rapid mapping of pressure fields produced by clinical HIFU transducers, in addition to providing invaluable information about the evolution of cavitation dynamics during HIFU exposure.