bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonance-enhanced compact nonlinear acoustic source of low frequency collimated beam for imaging applications in highly attenuating media
Authors: Pantea Cristian , Sinha Dipen N.
Published: November 2016

Acoustic imaging in highly attenuating materials requires special acoustic sources that can generate a collimated beam of low frequency. Lower frequencies, in the range of 10-120 kHz, have the advantage of deeper penetration in the medium due to lower acoustic attenuation. However, typical acoustic sources at these low frequencies have a large beam spread, resulting in poor lateral resolution. We report on the latest advancements in the development of a very compact source, with approximate dimensions of a cylinder with a diameter of 25-50 millimeters and approximately 10 mm tall. Low frequency, collimated and steerable acoustic beam source are some of the main characteristics of this source. The newly developed source takes advantage of (1) frequency mixing in an acoustical nonlinear fluid in a cavity to generate the difference frequency of two high frequencies, around 1 MHz, and (2) resonance enhancement of the difference frequency in the cavity. An order of magnitude enhancement in amplitude was observed between on- and off-resonance conditions, with a collimation of the beam of approximately 6 degrees. Laboratory experimental data will be presented, and advantages over traditional and other nonlinear acoustic sources will be discussed.
Unconstrained manipulation of micro-particles using phase-control of standing ultrasound wave fields
Authors: Greenhall John , Guevara Vasquez Fernando , Raeymaekers Bart
Published: November 2016

We demonstrate a method of unconstrained manipulation of a spherical microparticle submerged in a fluid medium using a standing ultrasound wave field. The method works by displacing the microparticle in small increments through independent adjustment of the phases and amplitudes of two opposing ultrasound transducers. We model the dynamic behavior of the microparticle during each incremental displacement, taking into account the acoustic radiation force and the time-dependent and time-independent drag force acting on the microparticle. Using this dynamic model, we characterize the transient and steady-state behavior of the fluid-microparticle system during each incremental displacement as a function of the microparticle and fluid medium properties and the phases and amplitudes of the ultrasound transducers. The results show that the displacement time and percent overshoot of the microparticle trajectory are dependent on the ratio of the acoustic radiation force and time-independent damping force. We experimentally demonstrate the method by manipulating the microparticle in an unconstrained manner over multiple wavelengths. In contrast to existing methods that require all acoustic reflections be absorbed, this method takes all reflections into account, removing the need for a complex experimental setup.
Informational masking of vocal signals in a nonhuman animal
Authors: Bee Mark
Published: November 2016

Informational masking (IM) interferes with speech perception in the presence of multiple talkers. However, its impact on vocal communication in other animals has received little attention. This talk will present behavioral and neurophysiological evidence—much of it preliminary, circumstantial, or both—suggesting that frogs are also susceptible to IM in the context of vocal communication in noisy social environments. When choosing a mate in a chorus, female treefrogs must extract information related to a male’s suitability and quality as a mate from the temporal envelope of his vocalizations. In behavioral experiments, temporally structured maskers constrain a female’s ability to process the temporal envelopes of target vocalizations, even when targets and maskers are sufficiently different in frequency to be transduced by different inner ear papillae. (The frog’s peripheral auditory system—consisting of multiple sensory papillae that encode different frequency ranges of airborne sound—provides a natural “spectral protection zone” for minimizing the impacts of energetic masking in experimental studies of IM.) In neurophysiological experiments, potential correlates of IM can be observed in the responses of single neurons in the inferior colliculus. Future work will employ a multi-tone masking paradigm to determine how spatial separation, masker uncertainty, and target-masker similarity impact “subcortical” signal processing mechanisms in the context of IM and vocal communication.
Uninformative dynamic visual stimuli aid in segregating two similar acoustic stimuli, but not in detecting a single stimulus in noise
Authors: Maddox Ross K. , Pospisil Dean A. , Lee Adrian K.
Published: November 2016

Both the comprehension and detection of speech in noise are improved when the listener sees the talker’s mouth. There are multiple reasons for this, from basic physical temporal correlations to higher order linguistic cues; we have recently performed several experiments investigating the former. They were based on artificial stimuli with speech-like dynamics but no linguistic information. Auditory stimuli were a tone or tone complex with randomly modulated amplitude. Visual stimuli were a disc with a randomly modulated radius. We manipulated the correlation between the visual stimulus and each auditory stimulus. In all experiments, the visual stimulus provided no information about the task. In the first study, we presented two competing auditory stimuli and had listeners respond to events in the target stimulus (brief pitch or timbre fluctuations). Performance was better when the visual stimulus matched the auditory target than when it matched the masker. The second study employed a two-interval two-alternative forced choice detection task. Despite a range of stimulus variations, no effect of audio-visual coherence on auditory detection was ever observed. Taken together, these results suggest that listening improvements provided by visual stimuli derive from improvements in segregation and scene analysis, more than overcoming simple energetic masking.
Auditory scene analysis: Patterns of things to come?
Authors: Denham Susan
Published: November 2016

Perception depends on discovering and forming representations of sensory patterns to make sense of the world. Patterns playing out both in time and feature space allow sensory systems to form expectations, and provide a basis for decomposing the world into discrete objects and for detecting meaningfully novel events. Without expectations, the system has no way of autonomously evaluating its understanding of the world. However, patterns come and go. So, the perceptual system needs some way of allowing its operational representations to form and dissolve, dominate and yield, in a way that facilitates veridical perception. In this talk, I will discuss some of the issues of pattern discovery, maintenance, and deletion at different timescales and levels of complexity using exemplar models of SSA and auditory streaming, and new perceptual data.
In-plane wavefield detection in lattice structures via digital image correlation
Authors: Ruzzene Massimo , Trainiti Giuseppe , Schaeffer Marshall
Published: November 2016

We describe an experimental procedure to measure in-plane waves in an hexagonal lattice structure through digital image correlation. Measurement are performed by exciting the structure with a narrowband signal, then recording the evolution of the wavefield by using a single high-speed camera pointed at the lattice. By tracking the position of the lattice intersections, we are able to obtain the time evolution of the interpolated in-plane displacement field, which we use to separate the longitudinal and shear components of motion through Helmholtz decomposition. The proposed approach allows us to investigate the dispersion characteristics of P- and S-modes. For each of these two modes, we focus on the directionality of wave propagation by obtaining experimental dispersion surfaces, which are in excellent agreement with the theoretical ones. We also compare the RMS plots of the experimental displacement field to the components of the group velocity vector for the P and the S -modes computed theoretically, showing the direction where energy preferentially propagates in the structure. Digital image correlation is a promising tool for investigating in-plane motion in lattice structures, displaying interesting features with respect to analogous techniques, such as the 3D Laser vibrometry.
Automated acoustic evaluation of concrete bridge decks
Authors: Zhu Jinying , Ham Suyun , Sun Hongbin
Published: November 2016

Chain drag testing is commonly used in current practice for bridge deck evaluation due to its low cost and ease of use. However, this method is subjective, and highly depends on the experience of the operators. Ambient noise caused by traffic affects the test speed and accuracy of results. This paper describes a recent research to develop an automated chain drag acoustic scanning system to detect delaminations in concrete structures, including bridge decks. The system consists of an array of chains, a noncontact MEMS microphone sensor array, multi-channel data acquisition device, positioning system, and signal processing schemes. The multi-channel design improves the spatial coverage and resolution of testing. An algorithm for interpreting acoustic signals from the automated chain drag test is developed. This automated system will enable real time visualization of tested areas. Compared to the conventional manual chain drag test, the automated system provides improved accuracy, spatial resolution, repeatability, and practicality.
Electromagnetic acoustic transducers for nondestructive inspection of dry storage canisters for used nuclear fuel
Authors: Cho Hwanjeong , Choi Sungho , Lindsey Matthew , Lissenden Cliff J.
Published: November 2016

Inspection for stress corrosion cracking in stainless steel canisters that store used nuclear fuel must be done within a harsh environment that requires robotic delivery of the sensing system. The system must tolerate high temperatures and radiation and it must operate in constrained spaces. In order to be delivered robotically noncontact transducers are preferred. Electromagnetic acoustic transducers (EMATs) are noncontact transducers that can be made from materials capable of resisting high temperature and radiation and therefore are an excellent choice for this application. This presentation will describe the requirements of the dry storage environment, the ability of compact EMATs to detect cracks oriented both transverse and parallel to the wave vector using shear horizontal guided waves, and the nondestructive inspection methodology developed for full penetration weld regions. Laboratory experiments indicate that the pulse-echo mode is effective at detecting crack-like notches. B-scans constructed from the heat affected zone of welds show both the defects and the welds, which are distinguishable by their time-of-flight.
Extracting vibration characteristics of a guitar using finite element, modal analysis, and digital image correlation techniques
Authors: Huang Jiaqi , Patil Kiran , Baqersad Javad , Ludwigsen Daniel
Published: November 2016

The sound quality generated by the guitar depends on the vibration characteristics (i.e. natural frequencies and mode shapes) of this instrument. Thus, it is of particular interest to the guitar manufactures to be able to extract global information about the characteristics of the guitar. Traditional sensors can only measure at discrete locations. However, digital image correlation (DIC) can measure full-filed data on the surface of the structure. In the current paper, a finite element (FE) model of a guitar was developed using quadratic shell, and solid elements. An eigensolution was performed on the FE model to extract its natural frequencies and mode shapes. In order to validate the numerical results, a modal impact hammer test was performed on the instrument. Furthermore, a measurement was performed on the guitar using the DIC technique. In this measurement, the guitar was placed in a free-free configuration and was excited using a broadband excitation generated by a sound source. The response of the guitar to the excitation was recorded using a pair of high-speed cameras. The recorded images were processed to extract the natural frequencies and mode shape of the guitar. The results show strong correlation between the numerical model and experimental results.
High speed non-contact acoustic inspection method using multi tone burst wave
Authors: Sugimoto Tsuneyoshi , Sugimoto Kazuko , Kosuge Nobuaki , Kuroda Chitose , Utagawa Noriyuki
Published: November 2016

The non-contact acoustic inspection method using an air-borne sound can detect the cavity defect and crack near the measurement surface by using flexural resonance. By this method using a single tone burst wave, the length of the measurement time of a two-dimensional scan was a practical problem. This is because only one frequency was used for one sound wave emission so that a high signal to noise (S/N) ratio could be obtained with the laser Doppler vibrometer (LDV) of a weak laser power (e.g., He-Ne 1mW). However, two or more frequency can be used at the time of one sound wave emission (multi tone burst wave) by taking into consideration the difference of the propagation velocity of a sound wave and laser light. That is, it becomes possible to perform high-speed measurement as compared with the conventional method, using effectively the time & frequency gate for raising a S/N ratio by terminating measurement before the reflective sound wave reaches a laser head from the measurement surface. The experiment using a concrete test object was carried out and the validity of this multi tone burst wave as high-speed measurement was confirmed from the experimental result.
A data-driven solution to the invariance problem in speech perception
Authors: Nagamine Tasha , Mesgarani Nima
Published: November 2016

A fundamental and unanswered question of speech perception is the ability of a listener to map the highly variable acoustic features of phones to perceptual categories such as phonemes. Several solutions to this problem have been proposed, which include the motor theory, direct realist, distinctive features, and exemplar models. In parallel, the same problem has been studied extensively in algorithmic emulation of speech perception, where the first step is to estimate phonemic categories from the acoustic signal. The recent breakthroughs in machine learning methods, particularly models inspired by neural circuits, have resulted in nearly human-level performance. However, the strategy exploited by the models in these data-driven approaches remains elusive. Here, we analyzed a deep neural network model trained to perform the acoustic-to-phoneme transformation and determined the representational and computational properties of the network as it forms categorical distinctions. We found that the network internally created a representation of phonetic features, such as manner and place of articulation, and explicitly modeled the phone variability. Furthermore, the network selectively and non-linearly warped the acoustic space to separate the more similar acoustic distinctions. This study provides an empirical solution to the invariance problem that can be evaluated in perceptual and neural studies of speech perception.
Aspects of generating syntax-free word lists for quantifying speech intelligibility
Authors: Keller Stefanie , Hemmert Werner , Völk Florian
Published: November 2016

Several possibilities exist for quantifying speech intelligibility in noise, for example tests with single words or sentences. In the clinical routine, usually a single sentence test is used repeatedly, so that its vocabulary is often known to the patients. Thus, not only speech intelligibility but also long term memory is tested. New speech material is then required to explicitly address intelligibility. With the aim of providing new and optimized material, in this study, semantically, syntactically, and phonetically balanced words were taken from German sentence tests, based on databases for written and spoken German words. The resulting vocabulary consists of 54 words (nouns, adjectives, verbs, and numbers), for which word-reception thresholds were determined for ten normal-hearing subjects. With these thresholds, five-word lists of equal semantic context, equal word intelligibility, and with balanced phonetic cues were built. Non-acoustic advantages of an intelligibility test constructed this way are phonetic balance and semantic coherence without syntactic context, which aim at preventing syntactic and phonetic cues from affecting speech-intelligibility thresholds. As an initial verification, list intelligibilities were measured with the above subject sample. The results show no systematic difference for consonants and vowels. This indicates that the lists were successfully constructed without phonetic biases.
Eliciting natural conversational Lombard speech in realistic acoustic environments
Authors: Beechey Timothy , Buchholz Jorg , Keidser Gitte
Published: November 2016

Speech produced in noisy environments (Lombard speech) is characterized by a range of acoustic and phonetic changes. These changes stem from increased speaking effort which reflects communicative intent as well as decreased auditory feedback of the speaker’s own voice. An accurate understanding of real-world Lombard effects is important in hearing science for the development and assessment of signal processing strategies targeting realistic speech signals. While Lombard effects are well known from the literature, studies of Lombard speech have typically been based on relatively unnatural speaking tasks such as reading from a script and have been measured in simplified acoustic backgrounds such as stationary noise or constructed babble noise. Lombard speech produced under such unnatural conditions may differ significantly from speech produced in real-world settings. This study describes a novel method of eliciting natural conversational speech across five highly realistic everyday acoustic environments. Through the increased realism of both the speaking task and acoustic backgrounds this study aims to provide a more ecologically valid approximation of real-world Lombard speech than has been previously reported. Based on recordings of conversations between 10 pairs of young, normal-hearing people, a continuum of ordered acoustic and phonetic changes in speech is described in relation to changes in acoustic environments and is related to self-reported listening effort ratings across acoustic environments.
Variation in normal hearing thresholds predicts word recognition in noise
Authors: Van Engen Kristin
Published: November 2016

Analyses of speech identification data collected from young, normal-hearing adults often do not include measures of listeners’ hearing. Sub-clinical variation in hearing, it is assumed, will not significantly affect the identification of speech signals presented well above threshold levels. This study tested that assumption in the context of an experiment that investigated young adults’ recognition of words with few versus many phonological neighbors produced in clear and conversational speaking styles. Words were presented in speech-shaped noise at a + 5 dB SNR. A mixed effects regression analysis was performed to account for the contributions of lexical difficulty, speaking style, order of word presentation, and listeners’ hearing (as measured by pure-tone average (PTA)). This analysis showed, as expected, that correct identification was predicted by word type (easy > hard) and speaking style (clear > conversational). It also showed that identification improved over the course of the experiment. Finally, it showed that PTA was a significant predictor of identification for words produced in conversational speech, even for listeners with normal hearing (PTA range: -3.33-11.66 dB; mean: 2.23 dB). These findings show not only that sub-clinical hearing differences can significantly affect speech identification, but also that speaking clearly can mitigate the effect.
Interaction of cognitive load, sentence predictability, and speech degradation in spoken word recognition and memory
Authors: Hunter Cynthia R. , Adams Caylee , Rund Laura , Pisoni David B.
Published: November 2016

Whether cognitive load and/or listening effort needed to understand degraded speech differentially affect bottom-up and top-down processes is not well understood. The current project examined effects of sentence predictability, speech degradation, and cognitive load on the recognition of sentence-final words and on the recall of short (low-load) or long (high-load) sequences of visual digits presented prior to each spoken sentence. In addition to main effects of sentence predictability and spectral degradation, word recognition in both high- and low-predictability sentences was modulated by cognitive load when accuracy was between 35 and 80 percent. Words were identified more accurately under low load than high load. Digit recall was affected by load, speech degradation, and sentence predictability. Results indicate that cognitive load affects processes used to identify words in both low- and high-predictability sentences, and that listening effort affects memory for visual digits.
Are suffixed words different? Evidence from a modified lexical decision task
Authors: Pycha Anne
Published: November 2016

We investigated whether listeners process suffixed words differently than prefixed words. We presented primes that combined a clear-speech root plus degraded-speech affix (such as kin-xx, where xx refers to degraded speech), and measured lexical decision RTs to subsequent clear targets (kin-ship). Degradation used low-pass filtering (< 500 Hz), such that affixes were speech-like but incomprehensible. Thus, the prime kin-xx sounds like a complete suffixed word, yet it is compatible with the target kin-ship and should not compete with it for activation. The crucial comparison was between prefixed (re-group) versus suffixed (kin-ship) targets, which were matched for frequency, familiarity, probability of phonotactic transition across morpheme boundary, and affix type-parsing ratio (Hay & Baayen, 2002). On each trial, participants heard a prime, a 1000 ms ISI, then a target to which they made a speeded decision. Pilot results (n = 5) suggest that comparable speech input activated suffixed roots less strongly than prefixed roots. While xx-group reduced RTs to re-group by a large amount (-236.65 ms), kin-xx reduced RTs to kin-ship by a much smaller amount (-133.20 ms). Pseudo-affixed words (resort, worship) did not show a comparable difference, suggesting that the effect arises from morphological constituency.
The perception of speech rate for time manipulated and vocoded sentences
Authors: Reed Paul E. , Montgomery Allen , Fogerty Dan , Adams Charley
Published: November 2016

Naturally produced fast speech reduces certain acoustic-phonetic features that may limit intelligibility relative to linear time compression. However, how reduction affects judgments of speaking rate has not been systematically investigated. The purpose of this study was to examine the effects of linear time compression and spectral reduction on judgments of speaking rate. Listeners provided speech rate judgments of sentences. Conditions compared rate perceptions for naturally spoken sentences at slow and fast rates with linearly time-compressed/expanded versions of the same sentence, matched for duration. Conditions also examined rate judgments for noise vocoded sentences that varied in intelligibility and signal-correlated noise that examined rate judgments based only on temporal acoustic features. Our preliminary results demonstrate that linear time-compressed/expanded sentences were judged as faster than naturally produced sentences. This difference was also found for noise-vocoded versions of the sentences, as well as for signal-correlated noise. Additionally, vocoded stimuli were perceived as faster than naturally produced stimuli. These preliminary results suggest that acoustic-phonetic reductions in naturally produced speech do not appear to increase the perceived speaking rate relative to linear time manipulations. Significantly, temporal properties of speech rhythm appear responsible for coding perceptual aspects of speaking rate independently from factors related to linguistic processing.
Online perception of coda glottalization in American English
Authors: Chong Adam J. , Garellek Marc
Published: November 2016

In American English, voiceless codas /t, p/ are often realized with glottalization on the preceding vowel. Previous claims suggest that such glottalization can serve to enhance /t/ or, more generally, voicelessness of coda stops. This study examines the timecourse of word recognition to test these claims. 40 American English listeners participated in an eye-tracking study, where they heard synthesized glottalized and non-glottalized versions of CVC English words ending in /p, t, b, d/ while looking at a display with two words presented orthographically. Target words were presented with a minimal pair differing in place of articulation (e.g., cop-cot), or voicing (e.g., bat-bad, cap-cab). Our results indicate that listeners fixated to target words ending in /t/ marginally faster when they heard the glottalized version and when the competitor presented was a word ending in /p/. Glottalization did not result in faster fixation to targets for words ending in /p/. We also found a strong inhibitory effect—lower proportion fixation to targets—for words ending in voiced stops when the preceding vowel was glottalized. Altogether, these results support the claim that glottalization enhances voiceless codas (both /t/ and /p/), but that the effect is strongest for /t/.
Washback and language change: An investigation of teachers’ perception of the Korean vowel length contrast
Authors: Lee Goun , Shin Dong-Jin
Published: November 2016

The goal of the current study is to investigate whether the vowel length contrast in Korean is retained in teachers’ perception due to a washback effect. Previous studies have demonstrated that the vowel length contrast in Korean has been completely lost in the production of contemporary Seoul Korean (Kang et al., 2015). However, considering that this vowel contrast is still being prescriptively taught in the elementary school curriculum, we hypothesized that teaching linguistically extinct contrasts might influence speech perception. In order to investigate whether Korean teachers have regained the vowel length contrast, we conducted two perception experiments. Twenty-three Korean elementary school teachers and 30 university students (control group) from the Seoul area completed a discrimination task as well as a forced-choice identification test in which vowel length contrasts were manipulated at a ratio of 1:3. The results showed that teachers’ perceptual identification accuracy was significantly higher than that of the control group. Interestingly, the control group’s identification accuracy also exceeded chance level, indicating that Korean listeners still retained some perceptual sensitivity. These results suggest that the Korean vowel length contrast may not be completely lost in perception, and also that a washback effect from language teaching may inhibit language change.
Acoustic cues underlying the adjustment to talker sex in perception of fricative consonants
Authors: Moore Ashley N. , Winn Matthew
Published: November 2016

Sibilant fricatives are perceived mainly by spectral peak frequency, but are also influenced by surrounding context, which includes the vowel following the fricative. The vowel contains formant structure, formant transitions out of the consonant, and information about talker sex. These factors affect fricative categorization, even if fricative energy remains unchanged. For example, frequency components in voices are lower for men than for women, and the perceived boundary between relatively high (“s”) and low (“sh”) fricatives is accordingly shifted down for men. In this study, we examined various acoustic cues that underlie accommodation to talker sex, including fundamental frequency (F0), vocal tract length (formant spacing), and breathiness/spectral tilt as they affect fricative perception. Stimuli included a fricative continuum between “s” and “sh” and a variety of vocalic contexts spoken by women and men that were controlled to vary by the aforementioned cues. Listeners identified fricatives in “s”- or “sh”-onset words, and responses were analyzed using binomial logistic regression to measure the effect of contextual cues. Results demonstrate that despite the strength of F0 as a cue for talker sex, formant spacing and spectral tilt contribute most to the context effect, consistent with the importance of spectral contrast in speech perception.
Bermudian English: An acoustic analysis of vowel properties with implications for sociophonetic variation
Authors: Holliday Nicole
Published: November 2016

Bermudian English is a variety of interest due to its distinctiveness from most varieties of British and American English, but to date, few studies have documented the properties of the dialect's vocalic system (Ayers 1933). This study provides an initial description of the vowel systems of Bermudian English speakers, especially as compared to the systems of speakers of Mainstream U.S. English (MUSE). The study was conducted with seven native Bermudian speakers between the ages of 18 and 21. Subjects participated in a word list task as well as a picture task to elicit naturalistic speech. Results of regression analyses comparing F1, F2, and F3 values of Bermudian speakers with formant values of Mainstream U.S. English speakers from Hillenbrand (1995). indicate that Bermudian speakers differ from MUSE speakers in several striking ways. Bermudian speakers produce significantly fronter /u/ and /o/, and lower /i/ than MUSE speakers. Bermudian speakers also show a near complete merger of /ɛ/ and /ae/, though speakers also show some variation between productions in the word list vs. picture tasks, indicating a potential casual/careful distinction. Male Bermduian speakers also show a merger of /iɹ/ and /ɛɹ/ which is a stigmatized production according to speakers, though this does not occur for female speakers. The differences between casual/careful speech in front vowels and the gender differences in the production of prerhotic vowels provide valuable directions for future sociolinguistic and phonetic work on the variety.
The role of visual speech cues in sound change: A study of the cot-caught contrast among Michigan speakers
Authors: Havenhill Jonathan , Do Youngah
Published: November 2016

Interspeaker articulatory variation has been argued to be a driving force in sound change (Baker et al. 2011), yet the factors governing such variation are not entirely understood. Fronted /ɔ/ in the Northern Cities Shift is characterized by an increase in F2, and can be produced through either tongue-fronting or lip-unrounding (Havenhill 2015), while fronted /u/ in British English is achieved through tongue-fronting alone (Harrington et al. 2011). We investigate the hypothesis that visual speech cues restrict the ways in which articulatory patterns may vary between speakers. Participants were exposed to congruous and incongruous audiovisual nonce word stimuli containing /ɑ/ and /ɔ/, produced by a Michigan speaker. The perceived vowel was identified by selecting a rhyming English word (e.g., the choices for [zɔt] were “cot” and “caught"). When paired with visual lip-rounding cues, participants perceived auditory /ɑ/ as /ɔ/. Yet the same auditory stimulus presented with unround lips was perceived as /ɑ/, suggesting that the visual cue may be sufficient to maintain a contrast, despite acoustic similarity. However, conditions are favorable for merger when speakers produce both /ɑ/ and /ɔ/ with unround lips. As a result, visibly distinct articulatory variants may be preferred when pressure to maintain a contrast is high.
Acoustics of speech, articulatory compensation, and dental overjet in Cantonese
Authors: Cheng Lauretta , Schellenberg Murray , Gick Bryan
Published: November 2016

Studies relating dental anomalies to misarticulations have noted that potential correlations appear to be obscured by articulatory compensation. Accommodation of tongue or mandible positions can help even individuals with severe malocclusion approximate perceptually typical speech [Johnson and Sandy, Angle Orthod. 69, 306-310 (1999)]. However, associations between malocclusion and articulation could surface if examined with acoustic analysis. The present study investigates the acoustic correlates of Cantonese speech as it relates to degree of overjet (horizontal overlap of upper and lower incisors). Production data was collected from native Cantonese-speaking adults, targeting the vowels /i, u, a/, and fricatives /f, s, ts, tsh/, previously found to be vulnerable phonemes in Cantonese speakers with dentofacial abnormalities [Whitehill et al., J Med Speech Lang Pathol. 9, 177-190 (2001)]. Measures of dental overjet and language background were included as well. Preliminary results from trained listeners show that productions were perceptually typical. Acoustic analysis consisted of spectral moments for fricatives and formant values for vowels. The results improve our understanding of the relationship between malocclusion, compensation and speech production in non-clinical populations.
Reduction of intervocalic coronal stops in colloquial words, formal words and pseudowords in American English: A large-scale production study
Authors: Kapatsinski Vsevolod
Published: November 2016

Words occurring in reduction-favoring contexts have been hypothesized to become associated with reduced sound variants, reducing more than other words even when the contexts disfavors reduction. In a controlled production study, this paper investigates both this hypothesis and its converse: that words occurring often in reduction-disfavoring contexts become associated with non-reduced sound variants, compared to pseudowords. 130 speakers of American English were recorded reading sentences. Interspersed among fillers, designed to prime either formal or colloquial style, were sentences containing intervocalic /t/ and /d/ in the flapping environment. These sentences formed triplets placing different words in the same context, e.g., “She is looking for the {butter; jitter; witter}.” Words expected to disfavor reduction were overattested in formal registers of the British National Corpus. Those expected to favor it were overattested in American movie subtitles, compared to British ones, and overattested in colloquial registers. Colloquial words exhibited significantly more flap and approximant realizations of the /t/ and /d/ than either formal words or pseudowords. Furthermore, within sound variant (flap vs. stop vs. approximant), colloquial words exhibited shorter closure durations, even with local speech rate controlled. However, pseudowords behaved like formal words, suggesting that full pronunciations are used by default, despite their vanishingly low frequency.
Articulatory movement in consonant clusters: A contrastive study of Japanese and English
Authors: Funatsu Seiya , Fujimoto Masako
Published: November 2016

We investigated the articulation of consonant clusters with Japanese and English speakers using the WAVE system (NDI Corp.). Until now we measured the displacement of tongue tip only, but in this study we also measured the displacement of the mandible. The subjects were three Japanese and two English speakers. The speech samples were 4 words: blat, bnat, plat, pnat. All these second consonants, /l, n/ are articulated with tongue tip placed behind alveolar ridge. These words were embedded in a carrier sentence, “Say X.,” and these sentences were uttered 5 times each in random order. The articulation time from first consonants, /b/, /p/, to second consonants, /l/, /n/, were measured. Specifically, the time from the highest point of the mandible to that of the tongue tip was measured. Overall average time was 131.2 ms (Japanese) and 48.1 ms (English). Two-way ANOVA (Language vs. Cluster) showed a significant main effect in Language (p<0.0001). This result suggested that for English speakers, the first and second consonants are strongly co-articulated, while in Japanese speakers, they are not co-articulated or weakly co-articulated. The measurement of mandibular displacement more clearly showed the difference of the strength of co-articulation between Japanese and English.
Source properties of dorsal fricatives
Authors: Redmon Charles , Jongman Allard
Published: November 2016

Present models of voiceless fricative acoustics assume excitation of the vocal cavity anterior to a narrow constriction by an aperiodic source generated from turbulence within that constriction (or in the case of dipole sources from interaction of the jet with an obstacle downstream). This model has been applied successfully to anterior places of articulation (labial to palatal) but for dorsal fricatives, i.e., velar /x/ and uvular /χ/, there is evidence to suggest the assumption of a line source may not hold. Rather, preliminary data from our lab and from studies such as Zeroual (ICPhS, 2003) and Shosted & Chikovani (JIPA, 2006) indicates intermittent presence of a mixed source due to passive vibration of the uvula, yet no study to date has directly addressed this element of the sound source in dorsal fricative production. Acoustic and aerodynamic data on dorsal fricatives produced by four speakers each of Arabic, Persian, and Spanish are presented to validate the nature of the dorsal fricative source component and the degree of cross-linguistic variation in production of these sounds. Measures of periodicity duration and cycle amplitude/shape are employed to estimate the oscillatory pattern of the uvula and model its contribution to the radiated acoustic signal.
A preliminary acoustic analysis of three-dimensional shape of the human nasal cavity and paranasal sinuses extracted from cone-beam CT
Authors: Kitamura Tatsuya , Takemoto Hironori , Makinae Hisanori , Yamaguchi Tetsutaro , Maki Kotaro
Published: November 2016

The shape of the nasal cavity and paranasal sinuses is complex and varies between individuals. Because the shape is almost stable during speech, the acoustic properties could constantly provide speaker specific information to speech sounds, that is, speaker individuality. In this preliminary analysis, the shape was extracted from cone-beam CT data for a subject using a machine learning technique and its acoustic properties were examined using finite-difference time-domain simulation. The transfer function from the glottis to the nostrils was calculated and the distribution pattern of the pressure anti-nodes was visualized at frequencies of major spectral peaks and dips. In addition, transfer functions were calculated when each of the paranasal sinuses other than the ethmoidal ones was occluded to identify which sinus caused which dip. As a result, the longitudinal resonance in the right or left half of the nasal cavity generated each peak, while the transverse resonance in the pharyngeal cavity caused the major dips. The right maxillary, sphenoidal, and frontal sinuses generated dips below 1 kHz. The left maxillary sinus and ethmoidal sinuses, however, contributed to generating not only dips but also peaks. [This research was partly supported by JSPS KAKENHI Grant Numbers 15K00263, 25280066, and 25240026.]
Visuomotor pursuit tracking accuracy for intraoral tongue movement
Authors: Fazel Vedad , Katz William F.
Published: November 2016

Visuomotor pursuit tracking (VMT) tasks are used to study the movement of the articulators in order to better understand the processes involved in speech motor planning and execution. Because most of this research has focused on lip/jaw tracking of sinusoids visually presented on a screen, little is known about the tracking capabilities of the tongue, or for visual targets placed in the oral cavity. The present study used a novel technique for measuring tongue (and jaw) VMT based on a 3D electromagnetic articulography (EMA) system. Streaming EMA data from oral sensors were used to construct a real-time avatar of the tongue which was shown to subjects on a computer monitor. Subjects also viewed a (virtual) intra-oral spherical target that they were required to “hit” with the tongue tip sensor. The target was programmed to move in a sinusoidal direction and was varied in frequency (Hz), direction, and predictability. Preliminary results suggest that tracking accuracy is inversely related to target frequency and is higher for vertical and horizontal motion than for lateral motion. The role of target predictability will also be described.
Surface phonetic or underlying phonological representations: A mismatch negativity study of Mandarin tone assimilation
Authors: Chien Yu-Fu , Fiorentino Robert , Yang Xiao , Sereno Joan A.
Published: November 2016

Phonological alternation, in which a sound changes depending on its phonological environment, poses challenges to spoken word recognition models. Mandarin T3 sandhi is such a phenomenon in which a tone 3 changes into a tone 2 when followed by another T3, which raises questions regarding whether the human brain processes the surface acoustic-phonetic representation or the underlying linguistic representation of Mandarin T3 sandhi words. We conducted a mismatch negativity (MMN) study examining this issue. Participants passively listened to a T2 word [tʂu2 je4] /tʂu2 je4/, a T3 word [tʂu3 ʐən4] /tʂu3 ʐən4/, a Sandhi word [tʂu2 jen3] /tʂu3 jen3/, or a mix of T3 and sandhi words in an odd-ball paradigm. All were interspersed with a T2 word [tʂu2] (deviant). Results showed an MMN only in the T2 and T3 condition but not in the Sandhi or Mix condition. The fact that the surface acoustic information in the T2 and Sandhi conditions was identical, yet yielding disparate MMN results suggests that Mandarin speakers process T2 and Sandhi words differently. These data provide evidence for a stored linguistic representation, either an underspecified or underlying tone 3 syllable, which must be operative when listeners map the signal during spoken word processing.
Effects of aero-tactile stimuli on continuous speech perception
Authors: Derrick Donald , O'Beirne Greg A. , De Rybel Tom , Hay Jennifer , Fiasson Romain
Published: November 2016

We follow up on research demonstrating that aerotactile information can enhance accurate identification of stop- and fricative-onset syllables in two-way forced-choice experiments (Derrick, et al., 2014) to include open-set identification tasks. We recorded audio and speech airflow simultaneously from the lips of two New Zealand English (NZE) speakers (one female, one male), and used these recordings to produce an auditory/aero-tactile matrix sentence test. The airflow signal is used to drive a piezoelectric air pump that delivers airflow to the right temple simultaneously with presentation of noise-degraded auditory recordings. Participants (including native NZE speakers with and without hearing impairment, and normal-hearing native non-NZE and non-native English speakers) listen to and repeat 5-word sentences presented in noise with and without simultaneous airflow. Their open-set responses are scored by the researchers. Custom-written software identifies the SNRs for 20% and 80% word identification accuracy using a dual-track adaptive algorithm, and these data are fitted to psychometric curves relating SNR to speech intelligibility. Psychometric curves for airflow and no-airflow conditions will be compared in order to identify the influence of airflow on continuous speech perception. Data collection is in progress, and the results will be presented at the ASA conference.
Characterizing ocean acoustic channel through databases: Issues, requirements, and methods
Authors: Yang Tsih C. , Huang San Ho
Published: November 2016

There is a growing interest in underwater acoustic telemetry. This calls for methods to evaluate the performance of various (proposed) modulation and equalization algorithms under the same channel conditions. An ideal solution is to develop acoustic channel simulators. However, this effort has not been fruitful since acoustic channel simulations (at practical communication frequencies) so far have failed to capture the characteristics of real ocean channels. Currently, acoustic communications still rely on field experiments for evaluation of the algorithm performance. The problem with this approach is that each experiment is usually tailored to a particular modulation scheme and the cost prohibits testing of many different algorithms under the same ocean conditions. Some data-based channel simulators have been proposed where realizations of the channel impulse response (CIR) functions are generated based on the scattering function estimated from real data but it is still not adequate. A scheme to build ocean channel database is proposed in this paper, where CIR is deduced from data on a fractional symbol-by-symbol basis with negligibly small channel estimation error (using the surrogate signal predication error as an indicator) so that the developers can test the performance of different algorithms under same, realistic ocean conditions.
Harbor trial of underwater acoustic communication using Doppler-resilient orthogonal signal division multiplexing
Authors: Ebihara Tadashi , Leus Geert , Ogasawara Hanako
Published: November 2016

Underwater acoustic channels are characterized by a severe spread in time and frequency. To provide a highly reliable communication environment in doubly spread channels for UWA communication, we have proposed Doppler-resilient orthogonal signal-division multiplexing (D-OSDM). D-OSDM is a combination of the OSDM technique and orthogonal multiple access, and it preserves orthogonality among data streams even after propagation through doubly spread channels. We have conducted test tank experiments and simulations, and have found that D-OSDM could cope well with time- and frequency-spread channels and that it achieves a good communication quality [1]. In this talk, we will show some results of our first sea trial of D-OSDM, that was performed on 21 June, 2016 at Hashirimizu port, Kanagawa, Japan. In this trial, the transmitter is fixed on the harbor quay, and the receiver is fixed on a remotely-operated survey boat. Acoustic communication was performed by moving the boat to generate a severe spread in frequency. The experiments show that D-OSDM achieves a good communication quality even if the boat moves at a speed of about 1.5 kt. [1] Tadashi Ebihara and Geert Leus: Doppler-Resilient Orthogonal Signal-Division Multiplexing for Underwater Acoustic Communication, IEEE J. Ocean. Eng. 41 (2016) 408-427.
Waveform designs for computationally efficient acoustic response estimation
Authors: Silva Jacob L. , Gendron Paul J.
Published: November 2016

Broadband source waveforms are constructed that allow for the minimum mean square error (MMSE) estimation of an observed acoustic response function with minimal computational effort at the receiver. The waveforms offers near perfect auto and cross correlation properties over the limited propagation delay spread of the acoustic response allowing for least squares estimation of the whitened response with simple matched filtering. MMSE estimation of the whitened response can be accomplished in many cases from this least squares estimate. We compare the approach to conventional maximal length sequences as well as Gold sequence to determine the merits of the approach we further demonstrate the approach for communications at low signal to noise ratios.