bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of a body’s structural impedance and scattering properties using correlation of random noise
Authors: Rakotonarivo Sandrine T. , Kuperman W. A. , Williams Earl G.
Published: May 2014

The structural or surface impedance matrix (or equivalently the inverse of the structural Green’s function) for an elastic body can be obtained by placing it in an encompassing and spatially random noise field and cross-correlating pressure and normal velocity measurements taken on its surface. The derived theory shows that the correlation method produces the exact analytic form of the structural impedance matrix. A numerical experiment is presented determining the structural impedance matrix of an infinite cylindrical shell excited by a spatially random noise field. These results are then used to compute the scattered field from a nearby point source, which is in agreement with known results. [Work supported by the Office of Naval Research.]
Cross language speech-in-noise perception by early Spanish-English bilinguals and English monolinguals
Authors: Piccinini Page E. , Garellek Marc
Published: May 2014

Bilinguals have shown a hyper-awareness of fine phonetic detail in speech, while also sometimes losing out on higher-level syntactic and semantic information in speech-in-noise studies. This study seeks to determine how bilinguals process speech in noisy environments across different language contexts. Specifically, this study tests whether bilinguals utilize certain phonetic cues to access higher-level information. Two experiments will be conducted. First, to determine how bilinguals process speech in noise in different language contexts, early Spanish-English bilinguals and English monolinguals learning Spanish listened to sentences mixed with white noise in English, Spanish, and code-switching (English to Spanish and Spanish to English) contexts. Preliminary results suggest early Spanish-English bilinguals perform significantly above chance on word identification in all contexts, performing best in the Spanish context. The second experiment will determine specifically which noise types (lower versus higher frequency) are most detrimental to word identification. This in turn will suggest what kind of phonetic information is utilized most by bilinguals versus monolinguals. These results will aid our understanding of how bilinguals could use their hyper-awareness of phonetic detail to overcome difficulties in other aspects of processing.
The effect of talkers' language dominance on subjects' speech production of sibilant fricatives
Authors: Shih Ya-ting
Published: May 2014

This study investigates the effect of talkers' language dominance on subjects' sibilant production in a bilingual community. Guoyu (Taiwanese Mandarin) has 3 sibilants: alveolar /s/, retroflex /ş/ and alveolo-palatal /ɕ/, while Taiwanese (a Southern Min dialect) only has /s/, which is palatalized before /i/. Previous studies have shown that Taiwanese-dominant speakers in Taiwan has a merged category of /s/, /ş/ and /ɕ/. In addition, they treat [s] and [ɕ] as allophones of /s/. On the other hand, Guoyu-dominant speakers have a more distinctive three-way contrast of sibilants. This study explores whether listening to talkers with different language dominances affects subjects' speech production of Guoyu sibilants. Two female talkers, one is Taiwanese-dominant and the other is Guoyu-dominant, recorded Guoyu words containing target sibilants in word-initial position with comparable vowels. Forty bilingual adults' productions were elicited in a repetition task blocked by talker. The spectral centroid is obtained from the middle 40ms of each sibilant, along with the onset F2 of the following vowel. The two acoustic measures were plotted against each other and separated by talker. Preliminary results show that these subjects' productions differ when prompted by different talkers. Additional statistical tests will be performed to explore this production difference.
Non-native vowel processing as reflected by neuronal architecture: Dynamic causal modeling of the magnetic mismatch response
Authors: Oliver-Roth Georgina , Iverson Paul , Teki Sundeep , Leff Alexander
Published: May 2014

The aim of this study was to examine how auditory vowel processing by native (L1) and non-native (L2) speakers is reflected in their neuronal source architecture and in coupling between brain regions. We used the magnetic Mismatch Response/MMNm to test automatic brain responses to within- and between-category vowels with English controls and English L1/French L2 speakers with a varying range of L2 proficiency. Additionally, participants performed a range of behavioral tasks which targeted vowel perception (category discrimination and vowel identification) and production. The MEG data from this study was analyzed conventionally and with Dynamic Causal Modeling/DCM in order to determine neuronal sources and the dynamic source architecture in the L1 and L2 brain. In summary, the right hemisphere supported the left during L2 vowel processing in low ability L2 speakers. Performance in L2 vowel category discrimination was linked to the MMNm for a vowel distinction which was particularly difficult for the L2 speakers. The MMNm indicated whether a speech sound had gained phoneme status in an L2. DCM showed that there was no difference both architecturally and functionally between an L1 speaker’s and a highly proficient L2 speaker’s brain with regards to vowel processing.
Word recognition in early bilingual adults for two degradation types
Authors: Shepherd Rachel , Bent Tessa
Published: May 2014

Early bilingual adults have difficulty perceiving speech in noise compared to monolingual adults; however, the cause of the deficit is unknown. Further, the extent to which this deficit extends to other types of degradation, such as source degradation (e.g., a nonnative accent) has not been investigated. The current study investigated word recognition under environmental and source degradation by 24 monolingual and 24 bilingual listeners, who learned English and at least one other language before age 6. Participants identified sentences produced by one native and one nonnative talker in both quiet and noise-added conditions. Although noise was more detrimental to bilinguals than monolinguals, the presence of a nonnative accent caused a similar decline for both groups. Results from standardized tests of vocabulary, reading, spelling, nonverbal intelligence, and phonological processing showed two differences between the groups: bilinguals outperformed monolinguals on the nonverbal intelligence test (Raven’s Standard Progressive Matrices) and bilinguals performed less accurately than monolinguals on the vocabulary assessment (Peabody Picture Vocabulary Test). Therefore, the speech-in-noise deficit for bilinguals may be traced to their weaker vocabulary knowledge. This study demonstrates that early bilinguals experience a word-recognition disadvantage under environmental degradation but not source degradation.
Effects of experience on the processing of phonetic contrasts in foreign-accented Spanish
Authors: Llanos Fernando , Francis Alexander L.
Published: May 2014

Non-native accented speech is typically less intelligible than unaccented speech. However, intelligibility improves with experience. Experience might improve intelligibility by guiding listeners’ expectations regarding the systematic divergence of specific acoustic cues from the native norm within the non-native context. If an accent imposes predictable changes on the acoustic cue patterns present in speech, then listeners experienced with that accent may change their judgment of what was said based on whether or not it was perceived in an accented context. In the present study, two groups of native speakers of Spanish with and without significant experience with English-accented Spanish listened to Spanish sentences produced with and without a strong English accent. Each sentence ended in a Spanish word produced with or without English accent, but the voice onset time (VOT) of the first consonant in the word was artificially varied to form a continuum from bata (robe) to pata (paw). Experienced listeners showed a category boundary at a VOT of approximately 5 ms with no significant difference between accent conditions, suggesting that listeners were not affected by the perception of a familiar foreign accent. Additional results from inexperienced listeners and using non-word targets and fully English context sentences will be discussed.
Comparison across languages using the multilingual Matrix Test: Which language is best to survive in a cocktail party?
Authors: Kollmeier Birger , Hochmuth Sabine , Jürgens Tim , Warzybok Ania , Brand Thomas
Published: May 2014

The Matrix test (i.e., sentence test with fixed syntactic structure, but ten alternative words in each position which may lead to nonsense utterances) has the potential to overcome the inherently language-dependent incompatibilities of speech audiology. It is meanwhile available (with varying degree of supportive data) in Swedish, German, Danish, Dutch, American English, British English, French, Polish, Turkish, Spanish, Italian, Persian, Arabian, Finnish, and Russian. Several measures have been taken to make the tests as efficient, reliable and comparable across different languages as possible and to establish a de-facto standard. Using the Matrix concept it is also possible to estimate the “communication efficiency” of the different languages for this kind of sentences against each other. To eliminate the influence of the individual speaker, recordings with accent-free bilingual speakers (German-Russian and German-Spanish) were used to assess the respective speech reception threshold (SRT) for native listeners using stationary and fluctuating background noise. The results show both an inter-speaker and inter-language effect in the order of 3 dB. The latter is larger between German and Spanish than between German and Russian. The origin of these effects (such as long-term speech spectrum and the relative information content of consonants and vowels) will be discussed.
Effect of musical experience on tonal language perception
Authors: Chua Abigail , Brunt Jason
Published: May 2014

Potential connections between musical experience and language learning ability have been discussed and debated about in neurological and musical psychology literature. The identification of Mandarin tones was tested in non-Mandarin speakers. The dependent variable was the accuracy of tone identification in the mandarin phrases. A simple questionnaire was used to measure musical experience. Musical experience and experimental trial accuracy were related. Non-significant effects are also discussed. A t-test was used to compare identification accuracy of those with musical experience to those without musical experience. Musicians had higher test trial accuracy scores (M = 0.311, SD = 0.056), than nonmusicians (M = 0.275, SD = 0.03). The difference was significant t(31) = 2.228, p = 0.033, suggesting that the presence of musical training increases the effectiveness of skill in Mandarin tone identification for non-Mandarin speakers. There was a strong correlation for accuracy and overall years of practice r(29) = 0.4, p = 0.02. The more years of overall practice musicians had the higher the accuracy they demonstrated in the test trials. There was no correlation between accuracy and years of interval training, years of playing an instrument, years of advanced musical study, or years of current practice.
The informatics philharmonic
Authors: Raphael Christopher
Published: May 2014

I present ongoing work in developing a system that accompanies a live musician in a classical concerto-type setting, providing a flexible ensemble the follows the soloist in real-time and adapts to the soloist's interpretation through rehearsal. An accompanist must hear the soloist. The program models hearing through a hidden Markov model that can accurately and reliably parse highly complex audio in both offline and online fashion. The probabilistic formulation allows the program to navigate the latency/accuracy tradeoff in online following, so that onset detections occur with greater latency (and greater latency) when local ambiguities arise. For music with a sense of pulse, coordination between parts must be achieved by anticipating future evolution. The program develops a probabilistic model for musical timing, a Bayesian Belief Network, that allows the program to anticipate where future note onsets will occur, and to achieve better prediction using rehearsal data. The talk will include a live demonstration of the system on a staple from the violin concerto repertoire, as well as applications to more forward-looking interactions between soloist and computer controlled instruments.
Infrasonic wind noise in a pine forest; convection velocity
Authors: Raspet Richard , Webster Jeremy
Published: May 2014

Simultaneous measurements of the infrasonic wind noise, the wind velocity profile in and above the canopy, and the wind turbulence spectrum in a pine forest have been completed. The wind noise spectrum can be computed from the meteorological measurements with the assumption that the lowest frequency wind noise is generated by the turbulence field above the canopy and that the higher frequencies are generated by the turbulence within the tree layer [JASA 134(5), 4160 (2013)]. To confirm the source region identification, an array of infrasound sensors is deployed along the approximate flow direction so that the convection velocity as a function of frequency band can be determined. This paper reports on the results of this experiment. [Work supported by the U. S. Army Research Office under grant W911NF-12-0547.]
Noise and flow measurement of serrated cascade
Authors: Xu Kunbo , Weiyang Qiao
Published: May 2014

This study concerns the mechanisms of the turbulent broadband noise reduction for cascade with the trailing edge serrations. The turbulence spatio-temporal information were measured with 3D hot-wire and the noise results were acquired with a line array. The experiment is carried out in the Northwestern Polytechnical University low speed open jet wind tunnel. It is showed the spreading rate of the wake and the decay rate of the wake centerline velocity deficit increased with serrated edge compared to the straight edge, shedding vortex peaks appeared in the wake, and the three components of velocity changed differently with serrated trailing edge. Serrated trailing edge structure could reduce the radiated noise was proofed by noise results, and some peaks appeared in downstream of the cascade.
Peripheral effects of the cortico-olivocochlear efferent system
Authors: Delano Paul H. , Terreros Gonzalo , Robles Luis
Published: May 2014

The auditory efferent system comprises descending pathways from the auditory cortex to the cochlea, allowing modulation of sensory processing even at the most peripheral level. Although the presence of descending circuits that connect the cerebral cortex with olivocochlear neurons have been reported in several species, the functional role of the cortico-olivocochlear efferent system remains largely unknown. We have been studying the influence of cortical descending pathways on cochlear responses in chinchillas. Here, we recorded cochlear microphonics and auditory-nerve compound action potentials in response to tones (1–8 kHz; 30–90 dB SPL) before, during, and after auditory-cortex lidocaine or cooling inactivation (n = 20). In addition, we recorded cochlear potentials in the presence and absence of contralateral noise, before, during, and after auditory-cortex micro-stimulation (2-50 μA, 32 Hz rate) (n = 15). Both types of auditory-cortex inactivation produced changes in the amplitude of cochlear potentials. In addition, in the microstimulation experiments, we found an increase of the suppressive effects of contralateral noise in neural responses to 2–4 kHz tones. In conclusion, we demonstrated that auditory-cortex basal activity exerts tonic influences on the olivocochlear system and that auditory-cortex electrical micro-stimulation enhances the suppressive effects of the acoustic evoked olivocochlear reflex. [Work supported by FONDECYT 1120256; FONDECYT 3130635 and Fundacion Puelma.]
Mice with chronic medial olivocochlear dysfunction do not perform as predicted by common hypotheses about the role of efferent cochlear feedback in hearing
Authors: Lauer Amanda
Published: May 2014

Mice missing the alpha9 nicotinic acetylcholine receptor subunit (A9KO) show a lack of classic efferent effects on cochlear activity; however, behavioral and physiological studies in these mice have failed to support common hypotheses about the role of efferent feedback in auditory function. A9KO mice do not show deficits detecting or discriminating tones in noise. These mice also do not appear to be more susceptible to age-related hearing loss, and they do not show increased auditory brainstem response thresholds when chronically exposed to moderate-level noise. A9KO mice do show increased susceptibility to temporal processing deficits, especially when exposed to environmental noise. Furthermore, A9KO mice show extremely variable, and sometimes poor, performance when discriminating changes in the location of broadband sounds in the horizontal plane. Temporal and spatial processing deficits may be attributable to abnormal or poorly optimized representation of acoustic cues in the central auditory pathways. These results are consistent with experiments in humans that suggest artificial stimulation of medial olivocochlear efferents overestimates the actual activation of these pathways. Thus, the primary role of medial olivocochlear efferent feedback may be to regulate input from the cochlea to the brain (and within the brain) to maintain an optimal, calibrated representation of sounds.
Applications of interior fluid-loaded orthotropic shell theory for noise control and cochlear mechanics
Authors: Grosh Karl , Li Suyi , Wang Kon-Well
Published: May 2014

The vibration of shells with heavy interior fluid loading is a classical theory, as analyzed nearly 30 years ago by Fuller and Fahy in a series of seminal papers. Wave propagation for interiorly filled hydraulic lines, biological blood vessels, and pipelines represent classes of well-studied problems. In this paper we consider the application of this theory to two specific and seemingly disparate problems. The theory for interiorly fluid-loaded finite orthotropic shells with heavy interior fluid loading subject to end loading and with stiff end-cap terminations will be presented and compared to detailed experimental results. Application of this theory to the development of transfer matrices for developing networks of interconnected units of these systems (including the possibility of fluid flow between vessels) will be presented along with a discussion of the effects of fluid compressibility for the mechanics of outer hair cells of the mammalian cochlea.
Acoustic scattering from finite bilaminar cylindrical shells-directivity functions
Authors: Hayek Sabih I. , Boisvert Jeffrey E.
Published: May 2014

The spectra of the acoustic scattered field from a normally insonified finite bilaminar cylindrical shell has been previously analyzed using the exact theory of three-dimensional elasticity (J. Acoust. Soc. Am. 134, 4013 (2013)). The two shell laminates, having the same lateral dimensions but different radii and material properties, are perfectly bonded. The finite bilaminar shell is submerged in an infinite acoustic medium and is terminated by two semi-infinite rigid cylindrical baffles. The shell has shear-diaphragm supports at the ends z = 0, L and is internally filled with another acoustic medium. The bilaminar shell is insonified by an incident plane wave at an oblique incidence angle. The scattered acoustic farfield directivity function is evaluated for various incident wave frequencies and for a range of shell thicknesses, lengths, radii, and material properties. A uniform steel and a bilaminar shell made up of an outer elastomeric material bonded to an inner steel shell are analyzed to study the influence of elastomeric properties on the directivity functions. [Work supported by NAVSEA Division Newport under ONR Summer Faculty Program.]
Attenuation of noise from impact pile driving in water using an acoustic shield
Authors: Reinhall Per G. , Dahl Peter H. , Dardis John T.
Published: May 2014

Offshore impact pile driving produces extremely high sound levels in water. Peak acoustic pressures from the pile driving operation of ~103 Pa at a range of 3000 m, ~104 Pa at a range of 60 m, and ~105 Pa at a range of 10 m have been measured. Pressures of these magnitudes can have negative effects on both fish and marine mammals. Previously, it was shown that the primary source of sound originates from radial expansion of the pile as a compression wave propagates down the pile after each strike. As the compression wave travels it produces an acoustic field in the shape of an axisymmetric cone, or Mach cone. The field associated with this cone clearly dominates the peak pressures. In this paper, we present an evaluation of the effectiveness of attenuating pile driving noise using an acoustic shield. In order to fully evaluate the acoustic shield, we provide results from finite element modeling and simple plane wave analysis of impact pile driving events with and without a noise shield. This effort is supported by the findings from a full-scale pile driving experiment designed to evaluate the effectiveness of the noise shield. Finally, we will discuss methods for improving the effectiveness of the acoustic shield.
An acoustic threshold for third formant in American English /r/
Authors: Hamilton Sarah M. , Boyce Suzanne E. , Scholl Leah , Douglas Kelsey
Published: May 2014

It is well known that a low F3 is the most salient acoustic feature of American English /r/, and that the degree of F3 lowering is correlated with the degree to which /r/ is perceptually acceptable to native listeners as a “good” vs. “misarticulated” /r/. Identifying the point at which F3 lowering produces a “good” /r/ would be helpful in remediation of /r/-production difficulties in children and second language learners. Such a measure would require normalization across speakers. Hagiwara (1995) observed that F3 for /r/ in competent adult speakers was at or below 80% of the average vowel frequencies for a given speaker. In this study, we investigate whether children’s productions start to sound “good” when they lower F3 to the 80% demarcation level or below. Words with /r/ and vowel targets from 20 children with a history of /r/ misarticulation were extracted from acoustic records of speech therapy sessions. Three experienced clinicians judged correctness of /r/ productions. Measured F3’s at the midpoint of /r/ and a range of vowels were compared for these productions. Preliminary findings suggest that the 80% level is a viable demarcation point for good vs. misarticulated articulation of /r/.
Assessing functional auditory performance in hearing-impaired listeners with an updated version of the Modified Rhyme Test
Authors: Brungart Douglas , Makashay Matthew J. , Summers Van , Sheffield Benjamin M. , Heil Thomas A.
Published: May 2014

Pure-tone audiometric thresholds are the gold standard for assessing hearing loss, but most clinicians agree that the audiogram must be paired with a speech-in-noise test to make accurate predictions about how listeners will perform in difficult auditory environments. This study evaluated the effectiveness of a six-alternative closed-set speech-in-noise test based on the Modified Rhyme Test (House, 1965). This 104-word test was carefully constructed to present stimuli with and without ITD-based spatial cues at two different levels and two different SNR values. This allows the results to be analyzed not only in terms of overall performance, but also in terms of the impact of audibility, the slope of the psychometric function, and the amount of spatial release from masking for each individual listener. Preliminary results from normal and hearing-impaired listeners show that the increase in overall level from 70 dB to 78 dB that was implemented in half of the trials had little impact on performance. This suggests that the test is relatively effective at isolating speech-in-noise distortion from the effects of reduced audibility at high frequencies. Data collection is currently underway to compare performance in the MRT test to performance in a matrix sentence task in a variety of realistic operational listening environments. [The views expressed in this abstract are those of the authors and do not necessarily reflect the official policy or position of the DoD or the US Government.]
Eigenvector-based test for local stationarity applied to beamforming
Authors: Quijano Jorge E. , Zurk Lisa M.
Published: May 2014

Sonar experiments with large-aperture horizontal arrays often include a combination of targets moving at various speeds, resulting in non-stationary statistics of the data snapshots recorded at the array. Accurate estimation of the sample covariance (prior to beamforming and other array processing procedures) is achieved by including a large number of snapshots. In practice, this accuracy is affected by the requirement to limit the observation interval to snapshots with local stationarity. Data-driven statistical tests for stationarity are then relevant as they allow determining the maximum number of snapshots (i.e., the best case scenario) for sample covariance estimation. This work presents an eigenvector-based test for local stationarity. It can be applied to the improvement of beamforming when targets must be detected in the presence of loud-slow interferers in the water column. Given a set of (possibly) non-stationary snapshots, the proposed approach forms subsets of a few snapshots, which are used to estimate a sequence of sample covariances. Based on the structure of sample eigenvectors, the proposed test gives a probability measure of whether such consecutive sample covariances have been drawn from the same underlying statistics. The approach is demonstrated with simulated data using parameters from the Shallow Water Array Processing (SWAP) project.
Near- and far-field beam forming using a linear array in deep and shallow water
Authors: Culver Richard L. , Fowler Brian E. , Barber D. Chris
Published: May 2014

Underwater sources are typically characterized in terms of a source level based on measurements made in the free-field. Measurements made in a harbor environment, where multiple reflections, high background noise and short propagation paths are typical, violates these conditions. The subject of this paper is estimation of source location and source level from such measurements. Data from a test conducted at the US Navy Acoustic Research Detachment in Bayview, Idaho during the summers of 2010 and 2011 are analyzed. A line array of omnidirectional hydrophones was deployed from a barge in both deep and shallow water using calibrated acoustic sources to evaluate the effectiveness of post-processing techniques, as well as line array beamforming, in minimizing reflected path contributions and improving signal-to-noise ratio. A method of estimating the location of the sources while taking into account a real, non-linear array based on these measurements is presented. [Work supported by the Applied Research Laboratory under an Eric Walker Scholarship.]
The modal noise covariance matrix for an array of vector sensors
Authors: Evans Richard B.
Published: May 2014

A modal noise covariance matrix for an array of vector sensors is presented. It is assumed that the sensors measure pressure and gradients or velocities on three axes. The noise covariance matrix is obtained as a discrete modal sum. The derivation relies on the differentiation of the complex pressure field and the application of a set of Bessel function integrals. The modal representation is restricted to a horizontally stratified environment and assumes that the noise sources form a layer of uncorrelated monopoles. The resulting noise field is horizontally isotropic, but vertically non-isotropic. Particular attention is paid to the effect of the noise source intensity on the normalization of the covariance matrix and, consequently, to the effect of noise on the output of the array of vector sensors.
Investigation of subjective components of overall acoustic quality using binaural recordings made in Hartford's Belding Theater
Authors: Kocher Acadia A. , Vigeant Michelle C.
Published: May 2014

Previous research in concert hall acoustics has established correlations between listener preference for overall acoustic quality (OAQ) and a number of other subjective factors. A subjective study was conducted to determine the relative importance of several characteristics to OAQ. Subjects evaluated 18 signals based on listener envelopment, reverberance, tonal quality, and overall preference using five-point rating scales. The signals were presented individually over headphones. A total of 32 subjects with formal musical training and normal hearing were included in the study. Following a brief tutorial and training session, the test was divided into four sets, one for each of the subjective factors. All of the signals and sets were presented to each subject in a random order. The binaural recordings were made in the Belding Theater in Hartford, Connecticut. A loudspeaker on the stage played three short classical motifs that were recorded in three seat locations with two distinct settings of the hall’s variable acoustics system. The sound pressure levels of all signals were normalized to isolate the characteristics of interest. The data analysis identified relationships between the three factors and OAQ, with the most significant relationship between OAQ and tonal quality. [Work was supported by NSF Grant 1302741.]
Amplitude modulation sensitivity in rooms
Authors: Zahorik Pavel
Published: May 2014

The physical effects of room acoustics on sound emitted from an amplitude-modulated (AM) source is well understood and can be effectively characterized by the modulation transfer function (MTF) of the room. Human sensitivity to AM is also well understood under conditions which minimize the acoustical contributions of the listening environment, and can analogously be characterized using the MTF concept. Although it may be predicted that AM sensitivity in a reverberant soundfield could be explained if both AM sensitivity in the absence of the soundfield and the MTF of the room are known, little empirical data exist in the literature to validate this prediction. Here, we summarize recent work in our laboratory that addresses this issue. A consistent finding is that predicted AM sensitivity underestimates measured sensitivity for reverberant soundfield listening. This result appears to depend critically on prior listening exposure to the soundfield, and is consistent with recent neural data from other laboratories. It may also explain why speech understanding in normal-hearing populations is typically unaffected by the acoustical degradations caused by reverberation. [Work supported by NIH-NIDCD.]
Designing an auditory lab including active acoustics
Authors: Sonnadara Ranil , Ellison Steve , Trainor Laurel , Bosnyak Dan
Published: May 2014

LIVELab, a new facility at McMaster University, has been developed in order to help support research in areas such as developing intelligent hearing aids, measuring the physiological impact of media presentations, understanding interactions between musicians, and determining effective sounds for medical and warning systems. This room combines a quiet performance space featuring a low nominal reverberation time with technology including active acoustics, multichannel playback, and integral measurement and instrumentation to create a sonically flexible facility for auditory research. The design of the room and its acoustic variability for supporting these research endeavors will be discussed.
Perceptually evaluating ambisonic reproduction of room acoustics
Authors: Clapp Samuel , Guthrie Anne , Braasch Jonas , Xiang Ning
Published: May 2014

Spherical microphone array technology allows for the recording of auditory scenes in three dimensions by decomposing a soundfield into its spherical harmonic components. The performance of the array is affected by certain factors in its design, including the size of the array, whether an open or a rigid sphere configuration is used, and the number of sensors and their placement scheme. Ambisonics is a system designed to reconstruct a soundfield from its spherical harmonic components. The process of ambisonic decoding determines the signals that are fed to each loudspeaker in the array to simulate a given soundfield. Such systems have certain accuracy constraints, particularly at higher frequencies, and different decoding methods can be used at those frequencies to recreate more accurate spatial cues, particularly ILD cues. This paper examines how to develop a decoding scheme that addresses the constraints in both the recording and playback phases, and uses binaural modeling to determine its efficacy. Reconstruction of both simulated and real rooms is examined, with respect to the accurate reproduction of important room acoustic metrics.
A review of hospital noise studies
Authors: Miller Melinda , Van Wyk Kenric , Murphy Kristen
Published: May 2014

Hospital noise concerns are on the rise due to detrimental health effects and the implementation of Value Based Purchasing, which affects federal reimbursements based on HCAHPS patient satisfaction scores. Because noise is one of the lowest performing categories in the survey, it is expected that demand for hospital noise surveys will increase. Therefore, it is useful to examine existing hospital noise measurement techniques to serve as a guideline for future work. This paper provides a summary of several noise studies of existing healthcare facilities conducted by Acoustics By Design (ABD) and others. The goal of the studies performed by ABD was to balance providing a comprehensive noise study (across multiple noise variation factors, such as time of day, and weekend and weekday conditions, department type, etc.) with providing a study that is time and cost efficient. We have found that this is best done through a combination of short term and long term measurements in close collaboration with hospital staff and administration.
The relationship between speech perception and production: Evidence from children with speech production errors
Authors: Cabbage Kathryn , Carrell Thomas
Published: May 2014

Children with speech sound disorders (SSD), for reasons that are not well understood, fail to produce age-appropriate speech production targets in isolation, words, and/or functional conversation. One line of research suggests these children exhibit underlying perceptual deficits for acoustic cues that distinguish similar phonemes, exhibiting particular deficits for those phonemes produced in error (e.g., /r/, /l/) (Monnin and Huntington, 1974; Shuster, 1998), although other studies have reported mixed results in children with SSD (Locke, 1980; Rvachew and Jamieson, 1989). In the current study, children with SSD and typically developing children were presented with a perceptual discrimination task involving a phoneme produced in error by the SSD children (i.e., /r/). Findings revealed two separate subsets of children with SSD. The first exhibited poor discrimination of /r/ while a second exhibited exceptionally good discrimination of the same contrast. Given that all children with SSD exhibited distorted /r/ productions, a follow-up acoustic analysis is being conducted to identify specific acoustic characteristics of the distorted /r/s in the two groups (i.e., the poor /r/ discriminators versus the excellent /r/ discriminators). The pattern of results relating the acoustical details of /r/ production in these two populations should contribute to a more refined model of speech sound disorders.
An auditory test battery for the assessment of executive functions
Authors: Espinoza-Varas Blas , Ding Kai , Lakhwani Sudha
Published: May 2014

Recent studies have examined the potential role of executive functions (EFs) on the speech communication ability of cochlear-implant, hearing-aid users, and other patients with disordered speech, language, or hearing; in many of the tests used to measure EFs, the stimuli are visual rather than auditory. We developed an Auditory Executive Function (AEF) test battery in which the stimuli consist of word commands (e.g., “quit,” “stop”) spoken either in stern or in lenient voice tone. The battery measures the speed and accuracy of voice-tone classification in four conditions: (1) in the absence of information or response conflict (baseline); (2) while attempting to inhibit potent but inappropriate responses prompted by conflicting ear-laterality information (inhibitory control); (3) while having to switch between incompatible response-mapping rules from trial to trial (cognitive flexibility); and (4) while having to monitor and update the word presented in the current trial and remember the word presented 2–3 trials prior to the current one (working memory). Relative to baseline, classification accuracy decreases with conflicting laterality information and more so with trial-to-trial switching of response-mapping rules, but only the latter condition decreased the classification speed. The AEF test battery is portable and fully automated. [Research supported by the Alcohol Beverage Medical Research Foundation.]
Effects of listener characteristics on foreign-accentedness rating of a non-standard English dialect
Authors: Morales Andrea , Warner Natasha
Published: May 2014

This project analyzes what characteristics of listeners affect whether they perceive Chicano English as foreign-accented English. Many Americans assume Chicano English (CE) is non-native English spoken by native Spanish speakers, but CE is often spoken as a native dialect of English. CE is a very common dialect in Tucson, Arizona, and this project examines the correlation between listeners' ethnicity, familiarity with Hispanic people, and political stance on immigration, and their perception of CE as foreign-accented. Stimuli are sentences read by CE and other Tucson speakers that contain phonetic environments where CE has features that distinguish it from Standard American English (SAE) . The listener population is Southern Arizonans of various ethnicities with varying degrees of exposure to CE and Spanish. The experiment uses a Foreign Accentedness Rating (FAR) task, as well as classification of stimuli as spoken by a Hispanic vs. Anglo speaker and background questions on listeners' language background and political opinions. Highly accurate identification of ethnicity is predicted, as well as correlations between some measures of the listeners' background and strength of FAR rating of CE speakers. Conclusions involve the effect of long-term exposure to a local dialect and sociolinguistic status on perceived degree of foreign accent.
Auditory-inspired pitch extraction using a synchrony capture filterbank for speech signals
Authors: Ramdas Kumaresan , Peddinti Vijay Kumar , Cariani Peter
Published: May 2014

The question of how harmonic sounds produce strong, low pitches at their fundamental frequencies, F0s, has been of theoretical and practical interest to scientists and engineers for many decades. Currently the best auditory models for F0 pitch, [e.g., Meddis and Hewitt, J. Acoust. Soc. Am. 89(6), 2866–2894 (1991)] are based on bandpass filtering (cochlear mechanics), half-wave rectification and low-pass filtering (haircell transduction and synaptic transmission), channel autocorrelations (all-order interspike interval statistics) aggregated into a summary autocorrelation, and an analysis that determines the most prevalent interspike intervals. As a possible alternative to autocorrelation computations, we propose an alternative model that uses an adaptive Synchrony Capture Filterbank (SCFB) in which groups of filter channels in a spectral neighborhood are driven exclusively (captured) by dominant frequency components that are closest to them. The channel outputs (for frequencies below 1500 Hz) are then adaptively phase aligned with respect to a common time reference to compute a Summary Phase Aligned Function (SPAF), aggregated across all channels, from which F0 is easily extracted.
Acoustic characteristics of the Lombard effect from talkers with Parkinson’s disease
Authors: Shrivastav Rahul , Skowronski Mark D. , Kopf Lisa M. , Rakerd Brad
Published: May 2014

Speech production in noise elicits the Lombard effect, characterized by an increase in vocal effort. In talkers with Parkinson’s disease (PD), noisy environments are a stressor to speech production. Recently, the intelligibility of speech from PD talkers speaking in noisy (additive multi-talker babble) and reverberant environments was shown to be more sensitive to both factors than speech from healthy talkers [Kopf et al., ASHA 7387 (2013)]. The current study investigated the acoustic properties of speech and how they change in noise and reverberation for PD talkers compared to healthy talkers. Healthy talkers increased their level and fundamental frequency in additive noisy environments and, to a lesser degree, in reverberant environments. PD talkers also changed their level and fundamental frequency but to a more limited extent compared to healthy talkers. Additional changes in speech production (speaking rate, articulation range, and voice quality) were observed in individual talkers from both groups.
The cepstral peak: A theoretic analysis and implementation comparison of a popular voice measure
Authors: Skowronski Mark D. , Shrivastav Rahul , Hunter Eric J.
Published: May 2014

Cepstral analysis of speech has traditionally provided two pieces of information: (1) the cepstral lag, which is a measure of fundamental frequency, and (2) the cepstral peak, which is a measure of the degree of periodicity. Cepstral analysis conveniently separates the effects of the vocal tract from the acoustic source without explicit vocal tract estimation. The cepstral peak of speech is a popular diagnostic tool for voice disorders and vocal treatment assessment, yet the expected value of the cepstral peak has not received sufficient theoretic treatment. Discrete-time analysis of the cepstrum of a periodic pulse train revealed that the cepstral peak is 1/2 for all pulse trains with integer fundamental period T samples. For the more general case of a non-integer period, a pulse train formed with sinc functions produces a cepstral peak of 1/2+ε where the magnitude of ε scales with 1/T. The cepstral peak of various test signals was compared to cepstral peak prominence [Hillenbrand et al., J. Speech Hear. Res. 37, 769–778 (1994)], and accuracy was improved by (1) zero-padding the log spectrum before inverse Fourier transformation, which provides cepstral interpolation, and (2) limiting spectral nulls, which trades off estimate variance and bias.
Objective measures of blind source separation and the intelligibility of separated speech
Authors: Goldhor Richard , Gilbert Keith , Boyce Suzanne , Hamilton Sarah
Published: May 2014

When multiple acoustic sources are present in an environment monitored by multiple microphones, each microphone’s response signal is typically a weighted and delayed mixture of the active source signals. Subject to important constraints, these mixtures can be processed using Blind Source Separation (BSS) methods to construct output signals representative of each of the “hidden” acoustic sources in isolation. An important objective measure of the quality of a given “separation solution” is the amount of mutual information remaining in the BSS output channels: the less mutual information across channels, the better the separation. Often, the acoustic signals of interest in a complex acoustic environment are speech sources, and the measure of separation quality that really matters to listeners is speech intelligibility—a subjective (perceptual) measure that cannot be directly computed by a signal processing system. Thus, it would be useful to know how well objective measures of separation quality, such as mutual information, correlate with intelligibility. We present results of perceptual and objective tests exploring the relationship between objective separation metrics and word intelligibility as estimated by listeners’ responses in word identification tasks, for target-word-in-carrier-phrase utterances recorded in an acoustic environment with masking speech babble and broadband noise sources.
Toward a scalable, binaural hearing device: Acoustics, interaural processing, and scene decomposition
Authors: Kollmeier Birger , Hiipakka Marko , Grimm Giso , Neher Tobias , de Taillez Tobias , Schröder Jens , Anemüller Jörn , Hohmann Volker
Published: May 2014

One of the aims of the focused research group “Individualized hearing acoustics” are elements of an assistive listening device that both fits the requirements of near-to-normal listeners (i.e., providing benefit in noisy situations or other daily life acoustical challenges) and, in addition, can be scaled up to a complete hearing aid for a more substantial hearing loss. A review is given on the current work on acoustically “transparent” open-fitting earpieces, algorithms for interaural cue enhancement, and for automatically detecting relevant changes in the acoustical scene that call for an altered processing strategy. The current prototype runs on the binaural, cable-connected master hearing aid (MHA) that includes earpieces that allow for approaching acoustic transparency. This can be achieved by individual calibration of the earpieces using in-situ in-ear measurements and electro-acoustic models of the earpieces and the ear canal. A binaural high-fidelity enhancement algorithm motivated by interaural magnification is evaluated in its benefit for normal and near-to-normal listeners. Finally, several acoustic event detection schemes are compared with respect to their applicability in real-life situations. They decompose the ambient acoustic signal into spectro-temporal basis functions and utilize machine learning classifiers to detect typical natural and artificial events. [Work supported by DFG.]
The effects of head-worn attire on measured head-related transfer functions
Authors: Nimick Stephen , Atkins Joshua , Nawfal Ismael
Published: May 2014

In this paper, we investigate measured changes in spatial perception presented by hats and other head-worn equipment. Particularly, helmets worn in sports, military and civil services (firefighters, police etc.) can affect spatial awareness and localization of wearers, possibly putting the wearer and others in danger. For this paper, a variety of hats were placed on a Head And Torso Simulator (HATS). The Head Related Transfer Function (HRTF) was measured in an anechoic chamber at a variety of angles around the HATS. The data will be analyzed to show the differences between various head-worn devices.