bluuebunny/crossref_metadata_2025 huggingface dataset:
Plane wave echo particle image velocimetry
Authors: Rodriguez Samuel , Jacob Xavier , Gibiat Vincent
Published: May 2013

This paper deals with the application of topological imaging to ultrasonic echo-particle image velocimetry (Echo-PIV). Echo-PIV is a recent alternative to optical PIV for measuring the instantaneous velocity field of a fluid flow previously seeded with small particles. It consists in imaging the flow with a ultrasonic array at a high frame rate. Topological imaging is a method that benefits from the refocusing properties of the time-reversal principle in a systematic way, so that a single plane wave illumination of the medium leads to a fine resolution. Multiple insonifications are then possible at very high speed allowing not only static images of the medium but successive images of a moving medium. Experimental results are presented for a fluid seeded with stone powder. Two cases are studied: a vortex flow and the propagation of water surface waves.
Influence of the bell profile of the trombone on sound reflection and radiation
Authors: Campbell D. Murray , Myers Arnold , Chick John
Published: May 2013

One of the most striking external features of a modern trombone is its wide and rapidly flaring bell. The bore profile of this final section of the instrument influences its musical behavior in a number of different ways, since it determines both the strength of the acoustical feedback from the instrument to the lips of the player and the nature of the radiated sound field. These effects have been explored in an experimental study in which a number of trombones have been progressively modified by the removal of annular sections of the bells. Measurements of input impedance, transfer function, and directivity of radiated sound are presented, and the implications for the timbre and playability of the instruments are discussed.
Axial vibrations of brass wind instruments
Authors: Moore Thomas , Kausel Wilfried , Chatziioannou Vasileios , Etchenique Nikki , Gorman Britta
Published: May 2013

It has been proposed that axial vibrations of the bells of brass wind instruments can lead to audible effects in the sound [Kausel et al. (2010)]. Using both laser Doppler vibrometry and a novel implementation of electronic speckle pattern interferometry, we have demonstrated that these vibrations exist, and that the magnitude is of the order predicted. [Work supported in part by a grant from the National Science Foundation.]
Effects of background noise alternating between two levels at varying time intervals on human perception and performance
Authors: Hathaway Andrew , Wang Lily M.
Published: May 2013

Heating, ventilation, and air-conditioning (HVAC) systems commonly produce noise in the built environment, and the increased noise levels that these systems can produce have been shown to impact occupant comfort. However, relatively little is understood about how the fluctuations in HVAC noise over time can impact human perception and performance. This research aims to measure human responses under HVAC-like background noise that is alternating between two different levels (one low and one high) at varying time intervals. Twenty-seven participants were tested over four 30 min sessions during which they were subjected to broadband noise at room criteria ratings of RC-29(H) and RC-47(RV) that alternated at certain time intervals. The time intervals of variation tested were 2, 5, 8, and 10 min, and would remain the same during one 30 min test session. The results of an arithmetic test dealing with short-term memory and a subjective questionnaire are presented to show whether or not shorter time intervals of variation have different effects than longer ones. [Work supported by a NASA Nebraska Space Grant.]
Background noise in Chinese schools – Student and teacher perceptions
Authors: Roy Kenneth P. , Li Jerry
Published: May 2013

A significant research study was conducted in 2011/2012 to evaluate the Acoustic Comfort in 10 primary/middle schools throughout China as a joint effort by the Green Campus workgroup (Tongji University, Shanghai), and Armstrong World Industries (Research and Development). In the fall of 2012, an entire grade school in Nanjing, China, was involved in a combination of renovated and new construction with a focus on the requirements of Chinese Standard GB50118 for acoustic design/performance of classrooms. These research programs all included both objective measurements of acoustic performance, and subjective perception by students and teachers of both speech clarity (architecture) and distractions and comprehension (noise). The noise aspects of these measurements and surveys will be addressed in this paper. The primary noise sources in these schools are mainly from outside the classroom itself and involve student activities in corridors and other classrooms, and adjacent transportation noise. Effectiveness of in-room acoustic treatments on these noise perceptions is also reviewed.
Planned versus achieved acoustical performance and user satisfaction for an office fit-out
Authors: Bessey Ryan
Published: May 2013

The purpose of the project was to move 500 office workers separated between two aging buildings into one new larger building. To this end, a team was formed to create an office fit-out design including several open plan offices, private offices, meeting rooms, boardrooms, a conference center, and a cafeteria to connect with the base-building infrastructure. Our role, as part of the design team, was to provide guidance such that the acoustical performance for new spaces was at least equivalent but preferably better than their existing counterparts. Factors that were considered included acoustic comfort, background sound level, speech privacy, and speech intelligibility. This paper summarizes our approach to the project, some difficulties that were encountered during construction, measured acoustical performance in both the newly constructed and existing buildings, and the statistical change in user satisfaction before and after the move determined via surveys.
Noise stress for patients in hospitals – A literature survey
Authors: Notbohm Gert , Siegmann Silvester
Published: May 2013

The growing number of publications on noise in hospitals reflects not only a rising interest in this theme during the last decades, but also an increasing noise exposure of the patients: the average SPL reported in literature between 1960 and 2005 has risen from 57 to 72 dBA in daytime and from 42 to 60 dBA at night. The hospitals in question differ substantially with regard to type of construction, technical equipment, and organizational issues. But especially for intensive care units (ICUs), the main sources of noise described in international research are similar: sounds from technical appliance such as alarms, noise caused by the staff talking or handling material, and communication systems such as overhead paging. With regard to patients in ICUs, sleep disturbances in terms of falling asleep and sleeping through are the greatest problem as assessed by questionnaires or by physiological measurements. They might have harmful effects on the outcome of the medical treatment influencing the duration of recovery and the need for sedative medication. Several intervention programmes for noise reduction are reported in literature combining a variety of methods such as acoustical insulation, sound level reduction with regard to equipment, and especially behavior modification of the staff.
Vocal strain in UK teachers: An investigation into the acoustic causes and cures
Authors: Durup Nick , Shield Bridget , Dance Stephen , Sullivan Rory
Published: May 2013

Recent surveys indicate that approximately 60% of UK teachers experience voice problems during their career. This costs £15M annually in teacher absence and can have a significant human cost for those involved. This study investigated the impact of classroom acoustics on teachers’ voice levels to determine if acoustic modifications of classrooms could reduce the vocal load placed on teachers. Measurements of teachers’ voice levels were made using an ambulatory phonation monitor (APM), which measures voice parameters directly from skin vibrations on the neck. Simultaneous sound level meter measurements of various parameters were also carried out in the classrooms. The room acoustic parameters of the classrooms were measured separately to the APM measurements. Measurements have been taken in a range of classrooms as part of a pilot study. Results will be reported as to the effects of different acoustic environments in the classroom on the teachers' voice levels.
Acoustic quality on board ships
Authors: Seiler Robin D. , Holbach Gerd
Published: May 2013

Approaches to determine acoustic quality on board ships are usually based on a three- or five-stage classification system using critical A-weighted sound pressure levels. At times other criteria such as the sound insulation between cabins, impact noise from upper decks, speech interference levels or general noise-rating curves are also taken into account. With regard to increasing requirements of passenger comfort and crew accommodation, a more detailed evaluation of auditory perception on board would be worthwhile. Furthermore, other industrial sectors have stated that psychoacoustic or room acoustic models are useful tools to analyze and guarantee product-sound quality. In order to find better indicators for the quantification of acoustic performance of (luxury) vessels, audio material was acquired at a sea trial and evaluated with the help of a paired-comparison listening test in the laboratory by 30 test-persons. Also, the possibility to comment the judgments was given to the subjects. The results were then analyzed by using the statistic model of the “Law of Comparative Judgment” and compared by correlation analysis with physical, psychoacoustic, and room acoustic parameters. Highly correlating parameters could be identified.
Acoustic instability of vortices
Authors: Naugolnykh Konstantin A.
Published: May 2013

Large plane is a powerful source of vortex. Disturbances of an axial vortex in a compressible fluid are unstable with respect to Kelvin wave development and produce acoustic wave generation. On the other hand system of counter-rotating vortices (Lamb dipole), with different intensity of vortices, as a result of instability collapse into the center of rotation of vortices. The characteristic time of collapse is in the reciprocal proportion the vortices intensity difference. The evolution of Lamb dipole, determined by the two competing processes of instability, is considered in the presented paper. The sound radiation of Lamb dipole can be used to estimate the vortex structure produced by large plane. The advent of large aircraft, with their attendant large and strong trailing vortex structures, made this a problem of considerable practical concern.
Strongly nonlinear waves – A new trend of nonlinear acoustics
Authors: Rudenko Oleg V. , Hedberg Claes M.
Published: May 2013

Strongly nonlinear waves (SNWs) and extreme states of matter are key physical concepts. A SNW is a wave whose amplitude is on the order of the material's internal strength. High-intensity light is a weak nonlinear wave (WNW) if its electric field is weaker than the intra-atomic: E ≪ 1011 V/m. A SNW irreversibly modifies a medium, up to its destruction. In vacuum a wave 1018 V/m is strong, when it creates electron-positron pairs. In acoustics SNWs must be distinguished from WNWs which also can display strongly nonlinear phenomena. When a shock front appears at a distance of 102−103 wavelengths in water, nonlinearity is weak but strongly expressed. The acoustic pressure is 105−106 Pa, much less than the internal pressure 2.2 × 109 Pa. However, impurities decrease the breaking strength, and waves create bubbles at smaller pressures. An explosive wave is also a SNW, breaking solids. Nuclear explosions may even create new chemical elements. For WNWs the equation of state can be expanded in power or functional series. However, these cannot be used in three cases. First, if the equation contains singularities, like for “clapping” and Hertz nonlinearities of heterogeneous solids. Second, if the series is divergent. Third, when the linear term is absent and the higher nonlinearities dominate. Such SNWs appear in mechanics and in quantum field theory. Mathematical models of SNW, solutions, and new phenomena observed experimentally will be presented.
Early onset of sound in Rijke tube with abrupt contraction
Authors: Matveev Konstantin , Hernandez Rafael
Published: May 2013

Rijke tube is a system convenient for studying thermoacoustic instabilities both experimentally and theoretically. Common Rijke setups involve tubes with constant cross-sections. With the goal to reduce supplied heat necessary to excite acoustic modes, a segmented Rijke tube is constructed comprising two pipes of different diameters. Experiments with regulated mean flow and supplied heat demonstrate that thermoacoustic instability in the segmented tube occurs at about half of the heat addition rate required for sound onset in a tube with uniform cross-section. This finding suggests that simpler experimental means can be used for studying thermoacoustic instabilities due to significant reduction of required heat and highest temperatures in the system. Also, some practical devices with complicated resonators may appear to be more prone to instabilities of this sort. Stronger coupling between acoustic modes due to their enhanced non-orthogonality in segmented resonators can result in richer nonlinear effects. A simplified energy-based model is developed that predicts the onset of instability in both straight and segmented Rijke tubes.
Hearing impaired cochlear response simulation
Authors: Simon Galvez Marcos F. , Elliott Stephen J.
Published: May 2013

A model is introduced which allows the vibration of the basilar membrane to be estimated for different degrees of hearing loss. The model is based on a discrete lumped parameter model of the human cochlea, which uses a three dimensional description of the fluid coupling. The hearing losses are assumed to be caused by the combined malfunction of the outer hair cells (OHCs), the inner hair cells (IHCs), and the endocochlear potential driving the system. OHC loss and damage to endochoclear potential are modeled by a reduction of the cochlear amplifier gain, which is obtained by reducing the feedback gain of the OHCs. IHC loss is modeled as an overall reduction in basilar membrane response. The distribution of OHC and IHC loss along the cochlea are derived using an iterative method, which matches the output vibration amplitude of the model to that assumed to generate the hearing impaired audiogram.
A perceptual model of auditory deafferentation
Authors: Lopez-Poveda Enrique A. , Barrios Pablo
Published: May 2013

Overexposure to intense sound produces temporary threshold shifts but permanent loss of afferent nerve terminals. Here, we present a vocoder designed to explore the perceptual consequences of this type of damage. The basic idea is that the spike train produced by an individual auditory afferent resembles a stochastically digitized binary version of the stimulus waveform and that the quality of the waveform representation in the whole nerve depends on the number of aggregated spike trains. Sounds were processed by filtering them into ten adjacent frequency bands. For the signal in each band, multiple spike trains were then obtained in an attempt to mimic the different representations of that signal conveyed by different auditory afferents innervating a given cochlear region. The aggregated spike train was multiplied by the original signal to obtain an acoustic version of the simulated nerve waveform. Tone-in-noise and speech-in-noise perception tests were performed by young, normal-hearing listeners using different numbers of afferents per frequency band. Results support that deafferentation impairs perception in noise more than in quiet. The proposed vocoder may be extended to model other types of hearing damage and to guide the design of hearing aids and cochlear implants.
Computational modeling of tinnitus development
Authors: Schaette Roland
Published: May 2013

Animal models and human neuroimaging studies have shown that tinnitus is generated through pathologically altered spontaneous activity of neurons in the central auditory system. Sensorineural hearing loss has been identified as an important trigger for the development of these aberrant patterns of neuronal activity, but the functional mechanisms that underlie this process have not yet been pinpointed. Using computational models, we have investigated which neuronal plasticity mechanisms could account for the development of neuronal correlates of tinnitus after hearing loss. We could show that a model based on the principle of activity stabilization through homeostatic plasticity can explain the development of neuronal hyperactivity as observed in animal studies. Moreover, the model’s predictions of tinnitus frequencies from the audiograms of patients with noise-induced hearing loss and tonal tinnitus are close to the observed tinnitus pitch. The model thus proposes a specific mechanism for how plasticity in the central auditory system could lead to the development of tinnitus after cochlear damage. The model also predicts that central auditory structures may show increased response gain, which could explain why tinnitus and hyperacusis often occur together. Moreover, the homeostasis model is consistent with recent experimental findings from tinnitus patients with normal audiograms, and it explains why auditory deprivation through an earplug can lead to the occurrence of phantom sounds.
Modeling loudness for impaired ears and applications to fitting hearing aids
Authors: Moore Brian C.
Published: May 2013

Models of loudness for impaired ears are based on the assumption that cochlear hearing loss can be partitioned into a component due to outer hair cell dysfunction, resulting in reduced frequency selectivity and a more rapid growth of neural response with increasing level (reduced compression), and a component due to inner hair cell dysfunction, which reduces the neural response at all levels. In the first two models that were developed in Cambridge, the filtering and compression that take place on the basilar membrane were modeled as sequential processes, which is not physiologically realistic. Nevertheless, the models were able to account for many aspects of loudness, and were used to develop methods of fitting multi-channel compression hearing aids that have proven to be effective. More recently, a model of loudness has been developed in which the filtering and compression are modeled using a physiologically plausible nonlinear filter bank. This has also been applied to the fitting of hearing aids. Factors not included in the models include central plasticity resulting from altered auditory input, possible consequences of the operation of the efferent system, and the influence of cognitive factors such as perceived distance of the sound source and perceived vocal effort.
Dynamics and stability of pneumatically isolated systems
Authors: Ryaboy Vyacheslav
Published: May 2013

Pneumatic vibration isolation is the most widespread effective method for creating vibration-free environments that are vital for precise experiments and manufacturing operations in optoelectronics, life sciences, microelectronics, nanotechnology, and other areas. The modeling and design principles of a dual-chamber pneumatic vibration isolator continue to attract attention of researchers. On the other hand, behavior of systems of such isolators was never explained in the literature in sufficient detail. After a brief summary of the theory and a model of a single standalone isolator, the dynamics of a system of isolators supporting a payload is considered with main attention directed to three aspects of their behavior: first, the static stability of payloads with high positions of the center of gravity; second, role of gravity terms in the vibration transmissibility; third, the dynamic stability of the feedback system formed by mechanical leveling valves. The direct method of calculating the maximum stable position of the center of gravity is presented and illustrated by three-dimensional stability domains. A numerical method for feedback stability analysis of self-leveling valve systems is provided, and the results are compared with the analytical estimates for a single isolator. The relation between the static and dynamic phenomena is discussed.
Simulation of structural dynamics using a non-polynomial method
Authors: Luostari Teemu , Huttunen Tomi , Monk Peter
Published: May 2013

In structural dynamics, the modeling of steady-state thin plate bending is an important but, especially at high frequencies, computationally challenging problem. When solving the displacement of an elastic thin plate, a fourth order partial differential equation (Kirchhoff's plate equation) needs to be solved. In addition, two boundary conditions are needed in order to uniquely solve the problem. Polynomial methods, such as the finite element method (FEM) and discontinuous Galerkin method (DGM), are generally used to solve the plate dynamics. At higher frequencies the computational burden of a low order FEM becomes rapidly unbearable. Consequently, non-polynomial modeling methods are investigated because of their capability to solve the problem more efficiently than the standard FEM. The non-polynomial method used in this study is called the ultra weak variational formulation (UWVF). The UWVF uses finite element meshes and it is essentially an upwind DGM with a special choice of basis functions. To date, the UWVF has been successfully used in electromagnetism, acoustics and linear elasticity. We shall show, using a mixture of theory and numerical examples, that the UWVF is feasible for thin plate problems. For these problems the UWVF basis consists of plane wave and evanescent (corner) wave functions.
Shock dynamics of random structures
Authors: Caresta Mauro , Langley Robin S. , Woodhouse Jim
Published: May 2013

Predicting the response of a structure following an impact is of interest in situations where parts of a complex assembly may come into contact. Standard approaches are based on the knowledge of the impulse response function, requiring the knowledge of the modes and the natural frequencies of the structure. In real engineering structures the statistics of higher natural frequencies follows those of the Gaussian Orthogonal Ensemble, this allows the application of random point process theory to get a mean impulse response function by the knowledge of the modal density of the structure. An ensemble averaged time history for both the response and the impact force can be predicted. Once the impact characteristics are known in the time domain, a simple Fourier Transform allows the frequency range of the impact excitation to be calculated. Experimental and numerical results for beams, plates, and cylinders are presented to confirm the validity of the method.
Exploring prosodic boundaries: Gradiency and categoricity of prosodic boundaries in articulation
Authors: Krivokapic Jelena , Mooshammer Christine , Tiede Mark
Published: May 2013

The prosodic hierarchy is a core concept of prosodic theory. Despite this, the number of categories in the hierarchy, and the structural relationships between them, is not clear. For English, a major and a minor category above the word level is usually assumed, and some studies have suggested additional categories [cf. Shattuck-Hufnagel and Turk (1996)]. Each of these category levels is assumed to be marked by categorically distinct boundaries, but experimental evidence for this view is sparse. In this work, EMA is used to investigate this notion of the prosodic hierarchy [following a preliminary analysis in Krivokapić and Ananthakrishnan (2007)]. Seven subjects read six repetitions of 48 sentences, each containing one, two or three prosodic boundaries, for a total of 56 boundaries per speaker. The predicted boundary strength varied from a weak clitic boundary to a strong sentential boundary. The produced boundaries are evaluated using a Gaussian mixture model analysis. The results bear on the question whether prosodic boundaries behave categorically (i.e., prosodic boundary values cluster within a small number of categories), or in a gradient manner (i.e., they are more evenly spread), thus supporting an alternative view of the prosodic hierarchy. [Work supported by NIH.]
Acoustic characteristics of intervocalic stop lenition in American English
Authors: Bouavichith Dominique , Davidson Lisa
Published: May 2013

Descriptions of English and other languages have claimed that intervocalic stops are often lenited to fricatives or approximants in connected speech, but few acoustic analyses of factors that affect lenition have been reported for American English [cf. Lavoie (2001)]. In this analysis, intervocalic voiced stops produced in bi- and trisyllabic words during story reading are examined (participants N = 14). The first result shows that American English speakers never lenite to fricatives, but rather produce approximants whenever lenition occurs. Second, stress plays an essential role: 51% of stops are lenited when stress is on the first syllable (e.g., “yoga”), but only 7% of stops lenite when stress is on the second syllable (e.g., “begin”). Overall, approximant productions are significantly higher for /d/ (which becomes a flap--63%) and /g/ (70%) as compared to /b/ (43%). For both stress placements, stop productions are longer and lower in intensity than approximant productions. Another significant factor is frequency, as higher frequency words are produced as approximants more often. These acoustic findings are generally consistent with Kingston’s (2006) claim that lenition within words and phrases occurs to minimize interruptions to the prosodic unit and indicate that the current constituent is ongoing.
Deriving functional load of phonemes from a prosodically extended neighborhood analysis
Authors: Kitahara Mafuyu , Tajima Keiichi , Yoneyama Kiyoko
Published: May 2013

The functional load of phonemes is a long-standing, but not a main-stream notion in modern linguistics: that some pairs of phonemes distinguish more words than other pairs is intuitively plausible, but hard to quantify. Meanwhile, neighborhood effects in word recognition and production have been one of the central topics in psycholinguistics, leading to a wide variety of investigations. However, the Greenberg-Jenkins calculation, the most common definition of phonological neighborhood, deals only with deletion, addition, and substitution of phonemes, lacking any consideration of prosody. For example, homophones, which cannot be segmental neighbors and thus excluded in most neighborhood research, can be distinctive if lexical accent is specified. The role of onset/rhyme distinction in neighborhood calculation has been discussed, but morae, another basic unit of prosody, were not mentioned in the literature. We propose a novel method for calculating the functional load based on a prosodically extended neighborhood analysis. It is a frequency-weighted neighborhood density summed across neighbors for a particular phoneme. Accentual distinctions, morae or syllables, and context effects within a word are taken into account. The proposed method gives a better account for the difference in the acquisition order of segments across languages. [Work supported by JSPS.]
Auditory free classification of nonnative speech by nonnative listeners
Authors: Atagi Eriko , Bent Tessa
Published: May 2013

Nonnative listeners are less accurate than native listeners at classifying talkers by regional dialect [Clopper and Bradlow (2009)]. This decrement may be due to less robust knowledge about the underlying sound structure of the target language or less extensive experience with socio-cultural phonetic variation in the target language. To disentangle the contribution of these two factors, this study examined native and nonnative listeners’ abilities to classify talkers who varied on another sociophonetic dimension: foreign accent. Unlike regional dialect variation, nonnative listeners typically have more experience with nonnative speech than native listeners, particularly for talkers with the same native language background. Using auditory free classification, native listeners of English and native Korean listeners classified talkers by perceived native language. Talkers consisted of nonnative talkers from six native language backgrounds and native talkers. Results demonstrated that native listeners were nearly perfect at grouping the native talkers together, but Korean listeners were much less accurate. Further, Korean listeners did not show an advantage for grouping Korean-accented talkers together. These results suggest that nonnative listeners’ less robust linguistic representations of the target language can hinder their abilities to attend to the acoustic-phonetic features that index dialect and accent categories. [Work supported by NIH-NIDCD Grant R21DC010027.]
Is consonant harmony assimilatory?
Authors: Maddieson Ian
Published: May 2013

Ohala (1990) claimed that vowel harmony is in origin a product of vowel-to-vowel assimilation across intervening consonants. Gafos (1999) essentially argued that consonant harmony may similarly be assimilatory. For this to be the case, intervening segments—typically vowels—must be capable of transmitting the harmonizing property. For some properties, such as nasality or lip-rounding such “spreading” is non-problematic as these can be properties of either consonant or vowels. An alternative view, e.g., in Hansson (2010), is that consonant harmony (albeit more narrowly defined) is a correspondence or copying process, not an assimilatory effect. In this paper a range of attested varieties of consonant harmony will be evaluated in terms of how plausibly an assimilatory component might be involved. The analysis indicates that consonant harmony patterns vary along a scale of their likelihood to be explicable as assimilatory in nature. Processes such as sibilant harmony may have an assimilatory part, as suggested by Whalen et al. (2011) and supported by a limited acoustic study reported here. However, harmony involving certain phonatory and laryngeal features, such as voicing (given that vowels are prototypically already voiced) or ejective production, does not plausibly involve assimilatory transmission of the harmonizing property.
The influence of multiple narrators on adults’ listening comprehension
Authors: Barker Brittan A. , Mosely Cornetta
Published: May 2013

Research has demonstrated that variable, talker information—such as the number of talkers—affects listeners’ perception and processing of linguistic information during various laboratory tasks. In particular, the detrimental effects of multiple talkers are highlighted during online speech perception tasks with little contextual support [isolated word recognition; e.g., Mullennix et al. (1989), Ryalls and Pisoni (1997), Sommers and Barcroft (2011)]. Nonetheless, it is unclear how multiple talkers might affect listeners’ perception of linguistic information in more complex spoken language tasks utilizing real-time, fluent speech. The present experiments were conducted determine if information contributed by multiple talkers influences adults’ auditory story comprehension in the presence of both quiet and background noise. The accuracy and reaction time data did not support the hypothesis that talker information affects the perception of linguistic information during auditory story comprehension. Thus these data bring to light theoretical perspectives that emphasize the importance of looking across experimental tasks to better understand talker-specific information’s pattern of influence on spoken language processing [e.g., Sommers and Barcroft (2006), Werker and Curtin (2005)].
Gestural reorganization under rate pressure interacts with learned language-specific phonotactics
Authors: Chitoran Ioana , Tiede Mark
Published: May 2013

Studies of articulatory reorganization occurring under rate-driven production pressure can provide a window into speech planning. Previous work shows evidence for stable coordinative structures in speech in which VC patterns reorganize to CV, VCC to CCV, and coronal-labial to labial-coronal order. Such stable modes are argued to result from general physical-biological constraints imposed by the articulatory/auditory system. Here we examine whether stable modes can also arise from linguistic patterns learned on a language-specific basis. The case study is Georgian, which licenses complex onsets disregarding sonority, following instead a phasing pattern whereby degree of overlap varies with order of constriction location (front-to-back /pt/ sequences are more overlapped than back-to-front /tp/). We analyze preliminary data from native speakers repeating the Georgian words [pata] and [tapa] as they tracked an accelerating metronome. Results show: (1) pAta > patA > pta (stress shift followed by elision, licensed by Georgian phonotactics); (2) tApa > tAp (elision only; consistent with Georgian order constraints, not with biomechanical constraints). These patterns are contrasted with similar data from French in which elision is not observed, consistent with French phonotactics. The data thus provide an example in which language-specific structure rather than biomechanical constraints alone mediate gestural reorganization. [Work supported by Fulbright-Hays.]
Perceived prosodic boundaries in Taiwanese and Swedish
Authors: Kuo Grace
Published: May 2013

Earlier studies have shown that listeners are not only able to detect the presence or the absence of a prosodic boundary but also able to distinguish between different boundary types. This study examined whether Taiwanese listeners (n = 18) and English listeners (n = 7) were able to predict the occurrence and the strength of the upcoming prosodic boundaries in Taiwanese and Swedish. For this purpose, we conducted a perceptual rating experiment, whose stimuli consisted of fragments with different boundaries (word, phonological phrase/tone sandhi domain, and intonational phrase), length (2-second and one-word) and quality (low-pass filtered and unfiltered.) Results show that both Taiwanese and English listeners can detect the occurrence and distinguish the boundaries in a foreign language when they are presented with longer fragments. Our finding strengthens the notion proposed in Carlson et al. (2005) that lexical information is not a necessary cue for prosodic boundary detection Another supporting evidence is that they could do the task nearly as well when the utterances were low-pass filtered. Significant correlations between ratings and the following relevant measures are found: f0 and voice quality.
Towards a model of intonational phonology of Turkish: Neutral intonation
Authors: Ipek Canan , Jun Sun-Ah
Published: May 2013

This study proposes an Autosegmental-Metrical model of Turkish intonation based on sentences produced in neutral focus, as part of our ongoing research investigating Turkish intonational phonology. Tonal patterns of utterances were examined by varying the length of a word and a phrase, the location of stress, syntactic structures, and sentence types. Preliminary results suggest that Turkish has a H* pitch accent, realized on the stressed syllable of most content words. Each content word forms one Prosodic Word (PW) whose left edge is marked by an L tone. There are two prosodic units higher than PW: an Intermediate Phrase (ip) marked by a final rising (LH) tone and an Intonational Phrase (IP) marked by various types of a final boundary tone. These three prosodic units are also distinguished by the degree of juncture. Interestingly, the ip-final LH boundary tone marks the right edge of a heavy syntactic constituent regardless of the length of the unit. Furthermore, the left edge of a nuclear pitch accent is also marked by a rising tone (LH), which is realized on the last syllable of the immediately preceding PW. The ip-final LH tone and the pre-nuclear LH tone are phonetically different and perceptually distinct.
Acoustic features of English sentence production for English and Chinese native speakers: Intonational and temporal patterns
Authors: Woodall Ashley , Liu Chang , Thomas Brenna , Reistroffer Katherine
Published: May 2013

Intonation is utilized by languages in order to differently convey intention, meaning, and emotion. Chinese, a tonal language, assigns F0 formant frequencies to lexically important components within words; whereas English, a stress language, changes F0 patterns according to the speaker’s intended meaning or emotion, especially changing near the end of a phrase. As Chinese speakers produce other languages, especially a non-tonal language such as English, it is uncertain whether their intonation is the same as a native speaker. The purpose of this study is to compare intonation across Chinese and English speakers. An acoustical analysis was completed on 16 English and 32 Chinese speakers producing List 1 of the Hearing In Noise Test (HINT) sentences. Preliminary results show that Chinese speakers produce sentences with longer absolute duration than English speakers. Intonation features of sentence production such as F0 contour and temporal contours, as well as temporal features of English sentences such as temporal gap and sentence and word duration will also be compared. Findings will show the effect of L1 tonal language on producing a stress language, such as English.
Rate variation as a talker-specific/language-general property in bilingual speakers
Authors: Kim Midam , Ackerman Lauren , Burchfield L. Ann , Dawdy-Hesterberg Lisa , Luque Jenna , Mok Kelsey , Bradlow Ann
Published: May 2013

Nonnative talkers tend to exhibit slower speech rates than native talkers at the group level. Here we ask whether individual variation in rate is language-general to the extent that L1 rate is a significant predictor of L2 rate within bilinguals. 62 nonnative English talkers participated in three speech production tasks in both their L1 (14 Cantonese, 14 Mandarin, 11 Korean, 4 Portuguese-Brazilian, 6 Spanish, 13 Turkish) and L2 (English), namely, reading a paragraph, spontaneously answering questions, and spontaneously describing a picture story. Two measurements of rate were automatically extracted from the recordings: speech rate (syllables per second), and articulation rate (syllables per second excluding silent pauses). As expected, L2 speech and articulation rates were overall slower than L1 speech and articulation rates for all tasks. Importantly, L2 speech rates and articulation rates were positively related to L1 speech rates and articulation rates, respectively. There were also significant differences in L2 speech rates and L2 articulation rates depending on L1 background and tasks. However, the positive relationship between L1 and L2 rates still holds with these other effects taken into consideration, suggesting that overall rate variation is partially an individual-specific property that transcends L1 and L2 within bilinguals. Acknowledgments: Vanessa Dopker and Chun Liang Chan. [Work supported by Grant R01-DC005794 from NIH-NIDCD.]
Bayesian localization of an unknown number of ocean acoustic sources
Authors: Dosso Stan E.
Published: May 2013

This paper considers localizing an unknown number of ocean acoustic sources when properties of the environment are poorly known. A Bayesian formulation is developed in which environmental parameters, noise statistics, and the number, locations, and complex spectra (amplitudes and phases) of multiple sources are considered unknown random variables constrained by acoustic data and prior information. The number of sources is determined during a burn-in stage by minimizing the Bayesian information criterion using hybrid optimization with an efficient source birth/death scheme. Optimal estimates and marginal posterior probability distributions for source locations are computed employing a variety of sampling approaches. Environmental properties and source locations and are treated as explicit parameters and marginalized using Markov-chain Monte Carlo sampling methods. In particular, environmental parameters are treated using Metropolis-Hastings sampling applied efficiently in a principal-component space, and source locations are treated using Gibbs sampling since the corresponding conditional probability distributions can be computed efficiently using normal-mode methods. Source and noise spectra are sampled implicitly by applying analytic maximum-likelihood solutions expressed in terms of the explicit parameters. This represents an empirical Bayesian approximation within a hierarchical formulation, and significantly reduces the dimensionality and improves sampling efficiency in the inversion.
Time-frequency localization issues in the context of sparse process modeling
Authors: Sen Gupta Ananya
Published: May 2013

Practical applications in acoustics such as shallow water acoustic communications often involve non-stationary processes that follow a time-varying sparse support. A classic example is acoustic scatter due to multiple reflections at the moving ocean surface and sea bottom, localized in the time-frequency domain as the sparsely distributed and time-varying Delay-Doppler spread function. In this work, we connect time-frequency localization of non-stationary processes with related issues in adaptive sparse sensing in the context of modeling and tracking the Delay-Doppler spread function. To this end, we provide an overview of methodological advances in adaptive sparse sensing techniques, and compare them over experimental field data collected as 15 m depth, 200 m range and moderate to rough sea conditions. We also comment on other adaptive techniques, such as least-squared error minimization algorithms, and discuss their extensions to the sparse sensing domain. We also explore the uncertainty principle underlying time-frequency representations, particularly in terms of how it influences the related and occasionally competing challenges to sparse process modeling: (i) restricted isometry criteria (RIP) for precise sparse reconstruction and (ii) choice of temporal window to localize the non-stationary Delay-Doppler spread function.
Performance limits of a compressive sensing application to beamforming on a line array
Authors: Ballard Jeffrey A.
Published: May 2013

Compressive sensing is a sampling theorem that exploits the sparsity of a signal in a domain Ψ, while being spread out in a sensing domain Φ. For example, a sinusoid time domain signal in Φ can be represented by one non-zero coefficient in the frequency domain Ψ. The time-frequency relationship is similar to the space-angle relationship that exists in underwater acoustics for an array of hydrophones. Wavefront curvatures that are spread out in the space domain can be represented in the angle domain by a sparse vector. This work investigates the performance limits of using compressive sensing to resolve signals in the angle domain, a task usually accomplished by beamforming. For compressive sensing, it has been shown that the performance of recovering a signal is related to the number of measurements, the number of non-zero coefficients, and the dimension of Ψ [Candes and Wakin, IEEE Signal Process. Mag. 21-30 (March 2008)]. Typically, in underwater acoustics, the number of hydrophones and their locations are fixed, so that the performance is found to be dependent on the number of non-zero coefficients (signals in the water) and the dimension of the angle domain (beams). [Work supported by ARL:UT IRD.]
Effects of multipath distortion on sparse signal parameter estimation
Authors: Byun Sung-Hoon , Kim Sea-Moon , Choi Hyun-Taek
Published: May 2013

Shallow underwater acoustic channel is typically characterized as sparse channel and the sparsity has been actively exploited to estimate the channel accurately. However, distortion of the multipath signal components degrades the performance of sparse approximation and the amount of distortion is dependent on specific time-varying channel condition which each multipath encountered during transmission. In this research we measure the signal distortion of multipath components and analyze its impacts on the sparse channel estimation. Especially, we are interested in the effects of the spatial difference of the distortion on sparse approximation of the multichannel receiver data. To this end, we use variety of experimental data sets which have different characteristics of multipath signal distortion and analyze the relation between the amount of distortion and the signal residual obtained from sparse approximation.
Numerical simulations of compressive beamforming with a vertical line array in the deep ocean
Authors: Edelmann Geoffrey F. , Rooney Ian , Gaumond Charles F.
Published: May 2013

Vertical line arrays (VLA) have been previously deployed in the deep ocean to detect surface targets in the far-field. Conventional beamforming is based upon l2 minimization due to the ubiquitous nature of the fast Fourier transform, but l2 minimization is not a unique method for solving the beamforming problem. Using a basis pursuit algorithm, this research project applied l1 minimization to target detection via beamforming. The compressive beamforming technique was shown to produce narrower beams, comparable noise resistance, and a relaxed requirement on the number of elements required to produce bearing-time records. Compressive beamforming was applied to simulated data and successfully detected surface targets in deep water with 30% of the elements of the full array. [Work supported by the Office of Naval Research.]
Directional sound source modeling by using spherical harmonic functions for finite-difference time-domain analysis
Authors: Sakamoto Shinichi , Takahashi Risa
Published: May 2013

Directivity of a sound source originates from the source’s shape and its size relative to wavelength. Therefore, the directivity varies with a frequency of a sound. In order to precisely simulate a directivity of a source in the finite-difference time-domain analysis, basically, it is necessary to model the shape of the source geometrically in detail. In the case of sources with complex shapes, however, geometrically precise modeling of the source shape requires small size of spatial discretization, and such a fine mesh discretization results in huge computational costs. In this study, applying a basic theory of Fourier analysis in which arbitrary directivity can be constructed by linear combination of spherical harmonic function, the condition of the sound source for the finite-difference time-domain method to reduce computational cost and to enable efficient analysis against a source with complex directivity characteristics is investigated. Spatial distribution of sound pressure of initial condition for respective spherical harmonic function and correction method of spectral characteristics for the finite-difference time-domain analysis are described.
The use of equivalent source models for reduced order simulation in room acoustics
Authors: Liu Yangfan , Bolton J. Stuart
Published: May 2013

The sound field in a room can be predicted by using the Boundary Element Method if the motion of the source is known along with the impedance of the room surfaces and furnishings: however, these computations are very time consuming, especially at high frequencies. It is known that the total sound field in a room consists of three components: (1) free space source radiation; (2) the incoming sound field reflected from the room surfaces; and (3) the outgoing sound field scattered from the source surface, particularly if it is large: e.g., a flat screen television. For the purpose of fast computation, an equivalent source method (ESM) can be adopted in which two sets of equivalent sources represent the incoming and scattered sound field components, respectively. When the free space component is known, the parameters of the ESM can be estimated by least squares approximations of the impedance boundary conditions on the room and source surfaces. Accuracy and computational load can be balanced by the choice of source order and the constraints placed on equivalent source locations. Simulation results will be presented to compare the performances of different ESM configurations.