bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing clarinet grunt and squeak notes to transitions in coupled oscillators
Authors: Cantrell Cherise , Vawdrey Joshua , O'Flynn Jeffrey , Andersen Bonnie
Published: April 2018

Under certain circumstance, a clarinet can cause an undesired squeak or grunt note. A squeak note is the clarinet shifting to a higher register—a higher set of harmonics—while a grunt note is the clarinet shifting to a lower register. One might hypothesize that such changes occur naturally in the clarinet over time. Analysis of such transitions with waterfall plots reveals a similarity to transitions made with thermoacoustically-driven coupled oscillators. For coupled oscillators, transitions can occur when the resonance of one oscillator passes through that of the other. This suggests that the cause of the undesired transitions in the clarinet are the result of one resonance (possibly the reed, which is affected by the embouchure) passing through that of the resonance of the other (likely the bore) rather than the clarinet itself relaxing to a different register as a function of time. Notes played on an artificially-blown clarinet in the second register were shown to be stable over several minutes. This suggests that changes in the embouchure drive the clarinet to grunt or squeak.
Impact of internal damping on forced vibrations of piano soundboards
Authors: Bader Rolf , Plath Niko , Pfeifle Florian
Published: April 2018

A Finite-Difference Model of a grand piano soundboard including internal damping is used to estimate the influence of the damping on the vibration of the soundboard. Theoretically, the increase of damping reduces eigenmodes and leads to forced oscillation patterns. Those patterns show considerable dependency of their vibrational shapes upon the driving point. In the extreme case of a heavy damping, the wave starting at the driving point does not reach the boundaries of the soundboard with much strength and is therefore not reflected. Then no eigenmodes exist anymore and the plate behaves like an infinite plate. In the other extreme of a soundboard not damped at all the eigenmodes of the soundboard clearly appear. The measured patterned of a soundboard are compared to the modeled ones and conclusions are derived in terms of the amount of damping in a real soundboard.
Sound localization performance of sample hearing protectors using standardized measurement methods
Authors: Thompson Eric R. , McKinley Richard L.
Published: April 2018

Sound localization is an important aspect in the performance of many tasks. These tasks frequently require the use of hearing protection to mitigate the potentially adverse effects of noise exposure. ANSI/ASA working group S3/WG94 has described four standard methods for measuring the effect of head-worn devices on sound localization. Data using three different hearing protectors and open ear and using three of the four methods described will be presented. The analysis techniques used for each of the three methods will be described in detail including the removal of front-back reversals and assessment of fine resolution location discrimination. The performance of the three hearing protectors and the open ear condition will be compared and contrasted. Data will be presented on proportion of localization discrimination and front/back reversals using Method 1 as well as localization error performance using Methods 2, and visual target acquisition and response time using Method 3. The performance will also be compared across the three methods. The results show that the measurement methods described are viable for the assessment of the effects of HPDs on performance associated with localization.
Standard methods to measure the effects of head-worn devices on sound localization
Authors: McKinley Richard L. , Thompson Eric R.
Published: April 2018

Four standard methods for measuring the effect of head-worn devices on sound localization in the horizontal plane have been developed by the working group S3/WG94. The objective was to establish methods that enable accurate, repeatable, and reliable measurement of sound localization performance for human listeners. The standard describes four measurement methods: (1) a low complexity, coarser method to estimate the proportion of location discrimination and front/back reversal errors using 8 loudspeakers; (2) a more complex, more robust method to measure localization error using 36 loudspeakers and a fine resolution response method; (3) a method to measure the functional impact of localization with degraded cues using 36 loudspeakers and an aurally guided visual search task; and (4) a method using 180 loudspeakers to precisely measure localization acuity. The methods will be described in detail.
Validation of numerical predictions of sonic boom metric variability due to turbulence
Authors: Stout Trevor A. , Sparrow Victor
Published: April 2018

Atmospheric turbulence scatters the sonic boom wavefront created by supersonic aircraft, causing random variations in the waveforms and spectra measured at the ground. To help assess the impact of turbulence, a time-domain algorithm based on the nonlinear KZK propagation equation has been developed which simulates turbulent fields via an approximate atmospheric theory. Two sets of recent supersonic overflight measurements at the NASA Neil A. Armstrong Flight Research Center and the Kennedy Space Center offer datasets which have been used to quantify the algorithm’s utility to simultaneously model atmospheric turbulence, nonlinearity, and absorption. The field campaigns simultaneously recorded measurements of both sonic boom waveforms along linear microphone arrays and also turbulence quantities suitable for use in the algorithm. The algorithm’s performance in predicting the measured variation of sonic boom metrics will be discussed. [Work supported by NASA via a subcontract from KBRwyle.]
Investigation of deturbing methods for sonic boom signatures
Authors: Xu Janet L. , Sparrow Victor
Published: April 2018

There is a desire to certify aircraft for supersonic flight using microphone measurements of the aircraft’s sonic boom signature on the ground. If the signature propagates through the planetary boundary layer before it reaches the ground, the signature becomes distorted because of atmospheric turbulence, corrupting the measurement. Methods to remove the turbulence effect, or deturbing methods, currently exist but are restricted to typical N-wave shapes or knowledge of the turbulence structure beforehand. This work investigates methods of deturbing sonic boom signatures independent of the N-wave shape and not requiring prior knowledge of turbulence. Improvements are made to the averaging method and subtraction method of deturbing, and a new method is investigated which uses audio fingerprinting, an audio identification algorithm used by music identification apps such as Shazam. The effects of each deturbing method are described using a wide set of physical and subjective metrics. [Work supported by the FAA. The opinions, findings, conclusions, and recommendations expressed in this material are those of the authors and do not necessarily reflect the views of ASCENT FAA Center of Excellence sponsor organizations.]
An improved Mach cut-off Model based on a 3-D ray tracing method and realistic atmospheric data
Authors: Huang Zhendong , Sparrow Victor
Published: April 2018

This research aims to assess the possibilities for Mach cut-off flight over land. An improved Mach cut-off model has been developed using a 3-D ray tracing method. Based on the Integrated Global Radiosonde Archive (IGRA), a radiosonde dataset from the National Centers for Environmental Information (NCEI) consisting of radiosonde and pilot balloon observations, the influence of realistic atmospheric profiles and flight conditions on cut-off Mach numbers is examined. Examples are given for certain busy air routes in the United States. [Work supported by the FAA. The opinions, findings, conclusions and recommendations expressed in this material are those of the authors and do not necessarily reflect the views of ASCENT FAA Center of Excellence sponsor organizations.]
Using psychoacoustics to examine a changing auditory system
Authors: Strickland Elizabeth A.
Published: April 2018

In the (long) time I was a student in Neal’s lab, I learned a rigorous, programmatic approach to psychoacoustics that was grounded in signal detection theory. Much of the work at that time followed up on Neal’s classic work in intensity discrimination and envelope processing, and how that might depend on processing within or across auditory channels. The research was tied to what was known about physiological processing in the auditory system. Research from other laboratories at the time suggested that the cochlea might adjust in response to sound via efferent feedback, and a paper by Liberman used a physiological approach that could be easily translated to psychoacoustic experiments. This inspired a search for behavioral evidence of efferent feedback to the cochlea, and an array of experiments were performed looking for effects of contralateral sound on psychoacoustic measures. While those experiments did not provide compelling evidence of efferent feedback, they sparked an interest that has continued to be a focus of my research. This talk will cover the array of experiments done at that time, and consider the results in the context of more recent results from my laboratory and other laboratories. [Work supported by NIH(NIDCD)R01 DC008327.]
Effects of age and noise exposure on the representation of amplitude modulation
Authors: Plack Christopher J. , Carcagno Samuele
Published: April 2018

Age and lifetime noise exposure were used as predictors for electrophysiological and psychophysical measures of amplitude modulation processing. Frequency-following responses (FFRs) were recorded from 61 listeners (20 young, 23 middle-aged, 18 elderly) to 0.6- and 2-kHz, 75-dB SPL, carrier tones amplitude modulated at 100 Hz. A pink noise highpass-filtered at 3 kHz was included to mask basal cochlear contributions to the FFR. Sinusoidal amplitude modulation detection (AMD) thresholds were measured for the same listeners for a 2-kHz carrier (40 and 80 dB SPL) and for three modulation frequencies (25, 50, and 100 Hz). The carrier was presented in notched pink noise to limit off-frequency listening. Lifetime noise exposure was estimated using a structured interview. A regression model was used to determine the independent contributions of age and noise exposure, while controlling for audiometric threshold. FFR amplitude for the 0.6 kHz carrier showed a marked age-related decline. Age was also associated with a significant increase in AMD thresholds. Lifetime noise exposure was not significantly associated with either FFR amplitude or AMD threshold. The results suggest that age is a stronger predictor of modulation processing deficits than lifetime noise exposure.
Context effects in modulation masking
Authors: Wojtczak Magdalena
Published: April 2018

Neal Viemeister is especially known for his contributions to our understanding of perception of amplitude modulation. Modulation masking and signal-to-noise ratio in the modulation domain have been shown to be strong predictors of speech intelligibility in noise. This study uses 40-ms amplitude-modulated tones embedded in a simultaneous 100-ms noise masker to show that for a given type of simultaneous masker, modulation masking can vary significantly depending on the type of stimulus that precedes the masked target. Three types of precursor were used to investigate these context effects, a 2-octave noise centered on the signal frequency (the same as the masker), a 7-component inharmonic complex tone, and a pure tone with a frequency equal to that of the target. All precursors had a duration of 400 ms and were presented in close temporal proximity at levels equal to those of the noise masker. The noise precursor produced on average a 7-8 dB [20log(m)] release from modulation masking. In contrast no change in the amount of masking and a small release of masking were observed for the pure-tone and complex-tone precursors, respectively. Mechanisms that may underlie the observed context effects will be discussed. [Work supported by NIH grant R01 DC015462.]
Broadband asymmetric wave transmission in dissipative acoustic/elastic metamaterials with diatomic oscillators
Authors: Li Bing , Alamri Sagr , Tan Kwek Tze
Published: April 2018

Asymmetric acoustic/elastic wave transmission have attracted increasingly attention recently. However, the propagation unidirectionality is always confined to a very narrow frequency band. This paper presents the development of a dissipative acoustic/elastic metamaterial with diatomic oscillators to realize “one-way” transmission in a broadband range. The effect of various types of dissipative oscillators on the asymmetric wave transmission is theoretically investigated and systematically discussed. By virtue of the surficial vibrational modes induced by the alternately arranged diatomic resonators and the merging effect of dissipative dashpot, the asymmetric transmission band is significantly broadened. Numerical results in frequency and time domains are verified using both lattice structures and continuum models. Preliminary experimental verification is further conducted. The broadband asymmetric transmission can be theoretically predicted and mathematically manipulated by careful design of the unit size parameters and deliberate selection of material properties, which could be potentially beneficial for applications in directional transducer and noise control.
Comparative study of impurities in lithium tantalite and lithium niobate
Authors: Chatterjee Chandrima , Miller Daniel , Ostrovskii Igor
Published: April 2018

S 38677 The point defects in ferroelectrics may influence the physical properties of phononic crystals LiTaO3 (LT) and LiNbO3 (LN). The initial wafers, periodically poled (PP) structures of LT with 1-mm-domains, and PP-LN with 0.45-mm-domains are investigated. Photoluminescence (PL) is taken at room temperature 310-nm -excitation. The slit width in optical spectrometer is set to 1 nm. The PL spectra of LT reveal multiple impurities including Fe + ,W, Th, Cs, Kr, Cu, Xe. Unlike PL from LN, there are no lines of the F-center, Ar and some other elements. The intensities of PL-lines in both LT and LN demonstrate a saw-type periodicity along the direction normal to the Z-axis. For instance, the PL line of Fe +  defect in LT varies ± 15% with periodicity about 200 ± 40 nm. In the case of PP LT phononic crystals, the difference in Fe +  line amplitude remains about the same; however, the periodicity becomes equal to a ferroelectric domain length of 1 mm. There is a difference between the two periodicities of charged defects in PP-LT and PP-LN; the positions of maxima in PL-lines are close to the interdomain walls in PP-LN, but it is not the case for PP-LT. Possible practical applications are discussed.
Trial-to-trial variability in talkers’ fundamental frequencies restrains spectral context effects in vowel categorization
Authors: Assgari Ashley , Stilp Christian
Published: April 2018

Perception of a given sound is influenced by spectral properties of surrounding sounds. For example, listeners perceive /ɪ/ (low F1) more often when following sentences filtered to emphasize high-F1 frequencies, and perceive /ɛ/ (high F1) more often following sentences filtered to emphasize low-F1 frequencies. These biases in vowel categorization are known as spectral contrast effects (SCEs). When preceding sentences were spoken by acoustically similar talkers (low variability in mean f0), SCEs biased vowel categorization, but sentences spoken by acoustically different talkers (high variability in mean f0) biased vowel categorization significantly less (Assgari et al., 2016 ASA). However, it was unclear whether these effects varied due to local (trial-to-trial) or global (across entire block) variability in mean f0. Here, the same sentences were arranged to increase/decrease monotonically in mean f0 across trials (low local variability) or vary substantially from trial-to-trial (high local variability) with equal global variability. On each trial, listeners heard a sentence filtered to add a low-F1 or high-F1 spectral peak to bias categorization of a subsequent vowel (/ɪ/-/ɛ/ continuum). Sentences with low local variability in mean f0 biased vowel categorization significantly more than sentences with high local variability. Relevance to studies of talker normalization will be discussed.
Evaluating mechanisms underlying nonspeech context effects in coarticulatory compensation
Authors: Viswanathan Navin
Published: April 2018

Human speech listeners overcome variability in the speech signal due to different speakers, rates, phonetic contexts etc., by demonstrating context-appropriate perceptual shifts. From a general auditory perspective, perceptual systems heighten contrastive spectral and temporal properties of the acoustic signal to help listeners cope with variability (Diehl et al., 2004). In this study, I focus on a spectral contrast account of perceptual coarticulatory compensation and evaluate the claim that listeners cope with coarticulation by tracking spectral averages across multiple segments (Holt, 2005) while ignoring spectral variability (Holt, 2006). In Experiment 1, using tone analogue contexts (Lotto & Kluender, 1998) I created multi-tone contexts such that the global spectral average of each trial was pit against the frequency of the final tone that immediately preceded the target speech. Interestingly, nonspeech context effects were determined by the frequency of the final tone rather than the global trial average. A follow up experiment 2 indicated that contexts with identical overall spectral averages can produce different effects on following speech depending on the final tone. These findings taken together call into question the assumed mechanisms underlying spectral contrast.
Cortical entrainment to speech under competing-talker conditions: Effects of cognitive load due to presentation rate and task difficulty
Authors: Iverson Paul , Song Jieun , Bradley Holly
Published: April 2018

Previous work has demonstrated that, when listeners attend to a target talker and ignore a distractor, their neural activity is more strongly entrained to the amplitude envelope of the target speech. Moreover, target-talker entrainment under these conditions can be higher for second-language listeners than native listeners, which might be due to the greater focused attention required to understand second-language speech. The present study manipulated the cognitive difficulty of the task in an attempt to make native-language listeners have entrainment results more like those of second-language listeners. Listeners heard simultaneous sentences spoken by male and female speakers, and had to detect semantically anomalous catch trials. The sentences had high or low semantic predictability (low-predictability sentences require more lexical processing to evaluate meaning) and were presented with short or long intervals between sentences (0.5 or 3.0 s, with shorter intervals forcing listeners to make a quicker evaluation of meaning). The preliminary results suggest that native-language listeners indeed have higher target-talker entrainment under more cognitively difficult conditions, suggesting that cognitive load may modulate focused attention to the target speech signal.
Ganong shifts for noise- and sine-vocoded speech continua in normal-hearing listeners
Authors: Roberts Brian , Summers Robert J.
Published: April 2018

Speech perception involves interpreting incoming sensory information in the context of stored linguistic knowledge. Lexical bias is the tendency to perceive an ambiguous speech sound as a phoneme that completes a word rather than a non-word; the more ambiguous the auditory signal, the greater the reliance on lexical knowledge. For example, a speech sound ambiguous between [g] and [k] is more likely to be perceived as [g] when preceding [Ift] and as [k] when preceding [Is]. The magnitude of this between-context difference—the Ganong shift—also increases when the listener experiences high cognitive load, limiting the resources available to process acoustic-phonetic information. In this study, an eight-step series between monotonized natural tokens of [gI] and [kI] was created using morphing software. Two continua—“gift”-“kift” and “giss”-“kiss”—were derived by adding [ft] or [s] to each step. High-resolution noise- (16-band) and sine-vocoded (32-band) versions were derived from these continua. Ganong shifts were substantially larger for sine- than for noise-vocoded stimuli, despite the greater number of channels for the former and similar slopes for the identification functions, perhaps reflecting the higher cognitive load associated with the relative spectral sparsity and less natural timbre of the sine-vocoded stimuli. [Work supported by ESRC.]
Pitch and timbre discrimination at wave-to-spike transition in the cochlea
Authors: Bader Rolf
Published: April 2018

A new definition of musical pitch is proposed. A Finite-Difference Time Domain (FDTM) model of the cochlea is used to calculate spike trains caused by tone complexes and by a recorded classical guitar tone. All harmonic tone complexes, musical notes, show a narrow-band Interspike Interval (ISI) pattern at the respective fundamental frequency of the tone complex. Still this fundamental frequency is not only present at the bark band holding the respective best frequency of this fundamental frequency, but rather at all bark bands driven by the tone complex partials. This is caused by drop-outs in the basically regular, periodic spike train in the respective bands. These drop-outs are caused by the energy distribution in the wave form, where time spans of low energy are not able to drive spikes. The presence of the fundamental periodicity in all bark bands can be interpreted as pitch. Contrary to pitch, timbre is represented as a wide distribution of different ISIs over bark bands. The definition of pitch is shown to also works with residue pitches. The spike drop-outs in times of low energy of the wave form also cause undertones, integer multiple subdivisions in periodicity, but in no case overtones can appear. This might explain the musical minor scale, which was proposed to be caused by undertones already in 1880 by Hugo Riemann, still until now without knowledge about any physical realization of such undertones.
Complex frequency modulation detection and discrimination at low and high frequencies
Authors: Whiteford Kelly L. , Oxenham Andrew J.
Published: April 2018

Whether frequency modulation (FM) is represented by place (tonotopic) or temporal (phase-locking) information in the peripheral system may depend on the carrier frequency (fc) and the modulation rate (fm), with only fcs below 4 kHz and fms below 10 Hz thought to involve temporal coding. This study tested the role of temporal coding in harmonic complexes by measuring FM detection and discrimination for two F0s (200 Hz and 1400 Hz), modulated at slow (1 Hz) and fast (20 Hz) rates, for tones with lower (2-5) or upper (6-9) harmonics embedded in threshold equalizing noise. Pure-tone FM detection was measured for fcs between 200 and 12000 Hz at the same fms. In detection tasks, participants selected which of two intervals contained FM. In discrimination tasks, participants selected which of three FM complex tones was incoherently modulated. Preliminary results suggest better FM detection for slow than fast rates, even when all tones are above 4 kHz. However, this effect was stronger at lower frequencies, where phase-locking cues may be viable. Most participants were only able to discriminate inharmonicity for slow fms in conditions with components below 8000 Hz. [Work supped by NIH grant R01DC005216 and an Eva O. Miller Fellowship.]
Frequency modulation improves sensitivity to interaural timing differences at high frequencies in the presence of noise
Authors: Kan Alan
Published: April 2018

Sensitivity to interaural timing differences (ITDs) at high frequencies has largely been attributed to slow amplitude modulations (AM) in the envelope. However, in noisy situations, high-frequency signal envelopes can easily be corrupted making AM less useful for sound localization. Previous work has shown that frequency modulation (FM) introduced into a high frequency pure tone can also yield sensitivity to ITDs. This suggests that FM may be an additional cue used by the auditory system to resolve high-frequency ITDs, which may be useful in noisy situations. This experiment tests the hypothesis that in-phase AM and FM are complementary cues that improve ITD sensitivity at high frequencies in the presence of noise. A 4-kHz tone stimulus with a fixed ITD of 500 μs was used, and had either 200 Hz AM, FM or in-phase AM + FM imposed. The signal-to-noise ratio (SNR) needed to achieve 70.7% correct in a left-right discrimination task was measured. Results showed that the SNR needed for FM was typically lower than AM, and AM + FM was significantly lower than either AM or FM alone. The results suggest that in-phase AM and FM may provide complementary cues that aid in discriminating ITDs at high frequencies in the presence of noise.
Linear nonreciprocal transmission of sound in a viscous fluid with asymmetric scattteres
Authors: Krokhin Arkadii , Walker Ezekiel , Bozhko Andrii , Neogi Arup
Published: April 2018

Reciprocity theorem is hold for wave equation due to time-reversal symmetry. Dissipative losses introduced by adding imaginary part to elastic modulus make sound propagation irreversible but the reciprocity theorem remains valid. In viscous fluid acoustic oscillations of local velocity follow the Navier-Stokes equation, which is not time-reversible. However, broken T-symmetry does not necessarily lead to nonreciprocity. Here we demonstrate that the necessary condition for nonreciprocal propagation in a viscous fluid is broken P-symmetry, which can be achieved by introducing asymmetric scatterers in a viscous environment. The experiment was done with a phononic crystal of Al rods in water. The rods have asymmetric cross-section in a form of a circular sector with an arc of 120 degrees. The measured transmission spectrum exhibits signatures of nonreciprocity within a range of frequencies from 300 to 450 kHz. The experimental results are in agreement with numerical simulations based on the linearized Navier-Stokes equation. The nonrecipocity is due to different viscous losses accumulated along sound propagation in two opposite directions with broken P-symmetry. Nonreciprocity increases for the rods with more rough surfaces since dissipation occurs mainly in a viscous boundary layer of thickness of few microns. Unlike previously proposed nonreciprocal devices based on nonlinearity or local spinning of fluid, our passive device is small, cheap, and does not require energy source. [Work supported by the NSF under Grant No. 1741677.]
Tunable acoustic energy dissipation by fluid-structure interaction in elastomeric, resonant metamaterials
Authors: Cui Shichao , Harne Ryan L.
Published: April 2018

Helmholtz resonators are a classic means to absorb low frequency acoustic waves with great effectiveness and straightforward implementation. Yet, traditional Helmholtz resonators are tuned to absorb a specific frequency of wave energy and are unable to adaptively tailor damping capability. On the other hand, recent research on elastomeric metamaterials offers concepts for large and tunable damping properties using internal constituents that buckle to trap large elastic energy when subjected to geometric or load constraints. The research reported here draws from the principles of Helmholtz resonance and constrained metamaterials to device a resonant metamaterial with tunable acoustic energy dissipation. Using the fluid-structure interaction of an internal beam-like member with the resonator chamber, the metamaterial absorbs acoustic waves at a target frequency and tailors energy dissipation by changing external constraints that relatively magnify or suppress the interaction between acoustic pressure and damped beam member. An analytical model is developed to qualitatively characterize the behavior of the metamaterial observed in the laboratory. From the combined experimental and analytical studies, it is found that the metamaterial may significantly reduce the sound pressure level at the targeted frequency range while modulating the broadness of the absorption effect by way of external load control.
Distorting an impulse wave with phononic metamaterials—An experimental study
Authors: Swearingen Michelle E. , Dorvee Jason R. , Albert Donald G. , Muhlestein Michael , Krieger Megan A. , O'Daniel James L.
Published: April 2018

Bench-scale experiments were performed to characterize impulsive signal distortion with metamaterial arrays. As physical models, the composition of these systems rely on acoustically rigid materials in order to be examined at these small scales. In the final design the propagation of the pulse was evaluated using an array of receivers. Unique elements of this experimental methodology include: the design and refinement of an anechoic chamber for high frequencies, an in-lab tunable impulse source for both high frequencies and high amplitude, bench scale experimental designs achieved through the 3-D printed configurations of computer aided designs (CAD) extracted directly from a numerical model for exacting representations of configurations, and a measurement scheme designed to map the 3-D distortion of the impulse wave. Data and a description of the experiment and results are presented. [The work described in this document was funded under the US Army Basic Research Program under PE 61102, Project T22, Task 01 “Military Engineering Basic Research"; Task 02 “Material Modeling for Force Protection;” Project T25, Task 01 “Environmental Science Basic Research” and was managed and executed at the US Army ERDC.]
Acoustic correlates of L2 Spanish judgments of accentedness and comprehensibility: A mixed-effects modeling approach
Authors: Zhou Ziwei , Nagle Charles
Published: April 2018

Two constructs—comprehensibility and accentedness—figure themselves prominently in listeners’ judgments of L2 (second language) speech. Correlational analyses have shown that they make separate contributions to such judgments (Derwing and Munro, 1995, 1997, 2005). As it is important to set realistic goals for adult L2 learners by prioritizing understanding over nativelikeness (Levis, 2005), recent studies began to examine the relative contribution of linguistic aspects, especially acoustic features, to comprehensibility and accentedness (Munro & Derwing, 1999; Kang, Rubin, & Pickering, 2010; Trofimovich & Issac, 2012). Consistent with this agenda, this study first examines the reliability of scores (produced by the 9-point Lickert scale) under modern measurement framework (e.g. multi-facet Rasch measurement model). Then, the relationship between acoustic features, including the confidence values (for each utterance) obtained using Google Cloud Platform speech recognition engine as well as suprasegmental features extracted using Prosogram (Mertens, 2014), and ratings are established using mixed-effects modeling techniques. Results indicate that, even though it can be shown that comprehensibility and accentedness are statistically distinct constructs, both ratings share a set of common acoustic correlates—speech time, standard deviation of pitch values, and normalized pairwise variability index (nPVI).
The effect of clear speech on listener perception of nonnative speech
Authors: Ferguson Sarah H. , Behrman Alison , Staples Jessica J. , Williams Stephanie M. , Ihrig Paige E.
Published: April 2018

Listener perception of nonnative speech may be measured as intelligibility, ease of understanding, or accentedness. The relationship among these variables is complex, as is the influence of clear speech on these measures. The purpose of this study was to explore the effect on listener perception of clear speech produced by Spanish-accented talkers of American English. Specifically, four questions guided this study: Does clear speech enhance intelligibility and ease of understanding? What is the effect of clear speech on accentedness? How does speaking style (conversational versus clear) influence the relationship among these perceptual variables? Does the presence or absence of supporting contextual information modify the relationship among intelligibility, ease of understanding, and accentedness? Twenty-eight female talkers of American English (half native English-speaking and half Spanish-accented) read aloud 56 short sentences using conversational and clear speech. The 56 sentences were comprised of 28 pairs, each containing a high- or low-probability final word. Young, normal-hearing, monolingual English listeners transcribed and rated ease of understanding for sentences presented in 12-talker babble, and then rated accentedness for sentences presented in quiet. Listeners assigned ratings using visual analog scales. Results and their implications for models of listener perception and clinical management of accentedness will be discussed.
Vowel perception in quiet and noise for native and non-native listeners: Analysis of vowel identifiability
Authors: Liu Chang , Jin Su-Hyun , Tao Sha
Published: April 2018

For a number of years, research on phonetic perception has been primarily focused on the percentage correct of phonetic identification (e.g., hit rate) without considering listeners’ response (e.g., false alarm). The purpose of this study was to compute d’ of English vowel identification in quiet and noise including both hit rate and false alarm for native and non-native listeners. Both data analyses showed native listeners outperformed non-native listeners for vowel identification in quiet and noise. However, the d’ data showed that the non-naïve disadvantage became larger in long-term speech shaped (LTSS) noise than in quiet, while the percentage correct data showed an oppositely finding that the non-native disadvantage was smaller in LTSS noise than in quiet. These preliminary results suggest that false alarms should be included in the data analysis of phonetic perception and the idenitificability (e.g., d’) based on the signal detection theory may be more appropriate to evaluate listeners’ capacity to identify phonemes. [Work supported by China Natural Science Foundation 31628009 and University of Texas at Austin Research Grant].
Speech perception for native and non-native English speakers: Effects of contextual cues
Authors: Zhong Ling , Liu Chang , Wang Cuicui , Tao Sha
Published: April 2018

Previous studies have shown that native English speakers outperformed non-native English speakers in perceiving English speech under quiet and noisy listening conditions. The purpose of this study is to investigate the difference between native English speakers and native Chinese speakers on using contextual cues to perceive speech in quiet and multi-talker babble. Three types of sentences served as the speech stimuli in this study: sentences with high predictability (including both semantic cues and syntactic cues), sentences with low predictability (including syntactic cues), and sentences with zero predictability (consisting random sequences of words). These sentences were presented to native-English and native-Chinese listeners in quiet and four-talker babble with the signal-to-noise ratio at 0 and -5 dB. Preliminary results suggested that native Chinese speakers primarily rely on semantic information when perceiving speech in quiet, whereas native English speakers showed greater reliance on syntactic cues when perceiving speech in noisy situations. The difference between native English speaker and native Chinese speakers on syntactic, and semantic information utilization in various listening conditions will be discussed. [Work supported by The University of Texas at Austin, Undergraduate Research Fellowship and China National Natural Science Foundation 31628009]
The production of American English vowels by native Japanese speakers in two different conditions
Authors: Nozawa Takeshi
Published: April 2018

Native Japanese speakers produced American English vowels /i, ɪ, ɛ, æ, ɑ, ʌ/ in two different conditions. First they read aloud one syllable words and non-words that contain these vowels on the word list. The vowels produced in this condition are believed to be what Japanese speakers believe typical of each English vowel. The Japanese speakers also reproduced English vowels uttered by native speakers. They were not told what vowel they would hear in each trial. The vowels produced in this way should be close to how each vowel sounds to the Japanese speakers, regardless of whether they correctly identify each vowel. The results revealed that in the “read aloud” conditions, /i/ and /ɪ/ are spectrally close, and so are /æ/ and /ʌ/ and in low central position. /ɑ/ is higher than /æ/ and /ʌ/. In “reproduction” condition, on the other hand, /i/ and /ɪ/ are spectrally more distant, and /æ/ is fronted. /ɑ/ and /ʌ/ spectrally closer than in “read aloud” condition. Taken together, it can be assumed that there is a discrepancy between how Japanese speakers believe English vowels sound and how English vowels actually sound to them.
Using high variability phonetic training to train non-tonal listeners with no musical background to perceive lexical tones
Authors: Silpachai Alif
Published: April 2018

Previous research has not extensively investigated whether High Variability Phonetic Training (HVPT) is effective in training listeners with no musical background and no prior experience with a tone language in their identification of non-native lexical tones. In this study, it was investigated whether HVPT is applicable to the acquisition of non-native tones by such listeners. Twenty-one speakers of American English were trained in eight sessions using the HVPT approach to identify Mandarin tones in monosyllabic words. Ten of the participants were exposed to words produced by multiple talkers (MT condition), and eleven participants were exposed to words produced by a single talker (ST condition). The listeners’ identification accuracy revealed an average 44% increase from the pretest to the posttest for the MT condition and an average 30% increase for the ST condition. The improvement also generalized to new monosyllabic words produced by a familiar talker and those produced by two unfamiliar talkers. The learning however did not generalize to novel disyllabic words produced either by a familiar talker or an unfamiliar talker. Comparisons between two groups further revealed that the improvement of the listeners in the MT condition was significantly higher than that of the listeners in the ST condition.
Language experience outweighs perceptual enhancement in category learning
Authors: Yang Meng
Published: April 2018

Some theorists claim that cues that contribute to the same acoustic percept are naturally coupled in category learning. In contrast, others claim that no pairs of cues are privileged in this way, and listeners simply learn cue correlations from language input. We compared the cue weighting and cue-shifting between pitch and breathiness, which are enhancing but do not signal a phonemic contrast in English (Experiment I), and pitch and closure duration, which are not enhancing but are correlated in signaling the English voicing contrast (Experiment II). When the cues were enhancing but not contrastive, English listeners successfully learned to weight the more informative cue higher. In contrast, preliminary results show that listeners have difficulty weighting the informative cue higher when the two cues are not enhancing but only contrastive. Results suggest that language experience outweighs auditory enhancement relationships in the perceptual coupling of cues.
Mathematical properties of generalized Bessel functions and application to multi-tone sinusoidal frequency modulation
Authors: Kuklinski Parker , Hague David A.
Published: April 2018

The generalized Bessel function (GBF) is a multi-dimensional extension of the standard Bessel function. Two dimensional GBFs have been studied extensively in the literature and have found application in laser physics, crystallography, and electromagnetics. However, a more rigorous treatment of higher-dimensional GBFs is lacking. The GBF exhibits a rich array mathematical structure in regards to its partial differential equation representation, its asymptotic characterization, and its level sets. In this talk/paper, we explore these properties and connect spectral and ambiguity function optimization of a multi-tone SFM signal to finding the location of the roots of these generalized Bessel functions.
Consensus detection of a Gaussian underwater acoustic source by a distributed sensor network
Authors: Hayward Thomas J. , Finette Steven I.
Published: April 2018

Probabilistic data fusion is a well-established algorithmic approach to the detection of underwater acoustic sources by a distributed sensor network. Direct communication of all of the network nodes with a fusion center would provide optimal joint detection via summation of log-likelihood ratios (LLR’s) across the nodes. However, a network that relies on a single fusion center for data exfiltration is not robust to the loss of the fusion center. Distributed detection mediated by dynamic consensus algorithms, which have their roots in the broader system-theoretic discipline of dynamic state estimation, offers an alternative that is robust to node loss. The present work illustrates the application of dynamic consensus algorithms to the distributed detection of underwater acoustic sources, taking as an example the detection of a stationary, ergodic Gaussian source in a shallow-water waveguide by a network of vertical-array nodes. A general definition of consensus algorithms is followed by the construction of particular linear consensus dynamical systems that (1) provide asymptotic agreement of the time-averaged consensus LLR with the optimal central-fusion LLR; and (2) equalize the mean cross-node disagreements of the consensus LLR's. Performance of centralized and consensus detection is compared in simulations. [Work supported by ONR.]
Calibration of low-cost sound level meters using machine learning techniques
Authors: Giraldo Jose , Bañuelos Irusta Alberto
Published: April 2018

The assessment of environmental noise pollution from complex sources that are not represented in traditional noise maps requires a long term monitoring network to manage citizen complaints, a network of low-cost sound level meters is a practical option to analyze real-world cases, however the accuracy of the measurements is a concern when this information is used to evaluate regulation accomplishment. Previous work on low-cost monitoring devices has been carried out in microphone comparison, processing board selection and recently in MEMS microphone use. In the present work the use of reinforcement learning techniques is explored to calibrate the sound pressure levels generated by a low-cost monitoring device using a class one sound level meter as reference in a continuous measurement setup. Machine learning based models are known to take into account strong non-linearities which are effective to get an alternative calibration method for low-cost sensors.
Improved pre-filtering stages for GCC-based direction of arrival estimation using smartphone
Authors: Küçük Abdullah , Ganguly Anshuman , Panahi Issa M.
Published: April 2018

Sound source localization (SSL) is one of the important areas in signal processing especially for hearing aid applications. Having at least two microphones and powerful processing capability makes smartphone as a good sound source locator for people who have hearing impairment. In our previous work, we showed that traditional Generalized Cross Correlation (GCC) method with spatial post-filtering stage would increase the performance of instantaneous estimation of direction of arrival (DOA). In this paper, we combine a spectral pre-filtering stage with our previous work to improve the noise robustness of the earlier method. By combining pre-filtering stage with GCC and post-filtering stage, we obtain robust DOA estimation under various realistic noise types. We experiment with several pre-filtering stages and study their impact on reducing root mean square error (RMSE) and mean absolute error (MAE) for DOA estimation. The real-time implementation of some of the proposed algorithms on smartphone is also presented.
On the relationships between auditory evoked potentials and psychoacoustical performance
Authors: McFadden Dennis , Pasanen Edward G. , Maloney Mindy M. , Leshikar Erin M. , Pho Michelle H. , Champlin Craig A.
Published: April 2018

Performance was measured on several common psychoacoustical tasks for about 70 subjects. The measures included simultaneous and temporal masking, masking by tones and by complex sounds, critical bandwidth, release from masking, and detection in the quiet. Also measured were auditory evoked potentials (AEPs, short and middle latency). Of interest were the correlations between psychoacoustical performance and the AEP measures, as well as any mean differences in the AEPs by sex and by menstrual cycle. Subjects were tested behaviorally in same-sex crews of 4—8 members; behavioral testing required from 8–10 weeks for each crew. Correlation and effect size were the primary measures of interest. Resampling was used to determine implied significance for the various comparisons studied. (This lab previously reported race differences in psychoacoustical performance and in otoacoustic emissions for these same subjects.) Several AEP measures exhibited large sex differences that were similar across race. Some correlations between psychoacoustical tasks and the various AEP measures were moderately high, but, across sex and race, the individual differences observed in psychoacoustical performance generally were not compellingly related to the individual differences in AEP latency or amplitude. N.F. Viemeister never worked on any of these topics. [Work supported by NIH/NIDCD.]
Speech formant changes due to repeated measurements, instruction, and simulated environments using both automated and manual feature extraction
Authors: Berardi Mark L. , Staples Jessica J. , Ferguson Sarah H. , Hunter Eric J.
Published: April 2018

Speech production can differ depending on how speech is elicited (e.g., spontaneous speech, read text, speaking style instructions, the speaking environment). Previous studies have shown different speaking styles being elicited via instruction (e.g., clear speech) or via the speaking environment (e.g., Lombard speech). There is evidence that the acoustic features of clear speech elicited by reading are similar to those observed in semi-spontaneous interaction between two interlocutors, but that clear speech changes are of a greater magnitude in the read speech than the semi-spontaneous speech. Ten talkers (five male, five female) performed read sentences (BVD) and picture descriptions in several conditions. The present study compares vowel formants from BVD sentences and spontaneously produced picture descriptions in a variety of conditions. Conditions were as follows: (1) repeated measures given the same instructions, (2) the effects of two speaking style instructions (conversational and clear), and (3) four simulated listening environments (quiet, 55 dB SPL of white noise, 63 dB SPL of white noise, and a reverberant environment) presented via earphones. Formants were extracted both manually (hand marked) and using automated techniques. Acoustic features relevant to the speaking styles and simulated conditions will be discussed in terms of the two extraction techniques.