bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural representation of speech sounds: Study using frequency following response.
Authors: Aravamudhan Radhika
Published: October 2009

The neural encoding of an acoustic signal begins in the auditory nerve and travels to the auditory brainstem and further to the auditory cortex. Previous studies have used nonspeech signals like tones and clicks to evaluate the integrity and synchrony of the auditory pathway. Most of the previous research has focused on how any acoustic signal is perceived by using behavioral methods. One of the main areas in understanding how we hear the signal depends on how this acoustic signal is represented in the auditory pathway. A number of studies have studied the acoustic parameters that influence the perception of speech, but very few of them have focused on how these acoustic changes are represented in the auditory pathway. Since the signal representation in the auditory pathway is very crucial to how the signal is perceived, studies that focus on the relationship between the changes in the input acoustics and its influence on neural representation become very essential. In the current project the neural representation of isolated vowels and vowels in CV context was recorded using human frequency following response. The results will be discussed in the paper.
How can a video game cause panic attacks? I. Effects of an auditory stressor on the human brainstem.
Authors: Lauter Judith L. , Mathukutty Elizabeth , Scott Brandon
Published: October 2009

The auditory brainstem response (ABR) was recorded during simultaneous binaural presentation of two types of sounds: (1) condensation clicks presented through in-the-ear earphones at 43.1/s, 60 dB nHL; and (2) recordings of breathing sounds, presented through supra-aural headphones, at levels adjusted by participants to be equivalent to the clicks. In alternate blocks, the breathing sounds were either: (1) a recording of quiet breathing (blocks 1, 3, and 5) or (2) a recording of erratic (stressed) breathing (blocks 2 and 4). The erratic breathing was modeled on a video game soundtrack in which the character was represented as running, wounded, and frightened. Four 2048-sweep ABR waveforms were collected in each of the five blocks, and the mean amplitude of ABR peak V was calculated over each set of four waveforms. Results indicate a significant decrease in the amplitude of ABR peak V during erratic breathing versus quiet breathing. Implications include (1) possible new evidence of the effect of selective attention on the ABR, (2) the potential for using auditory stressors to study the central physiology of emotional responses in humans, and (3) clues to physiological correlates of the effects of certain video games known to evoke panic attacks in susceptible players.
Challenges in evaluating the intelligibility of text-to-speech.
Authors: Syrdal Ann , Spiegel Murray , Rekart Deborah , Hertz Susan R. , Carrell Tom , Bunnell H. Timothy , Bickley Corine
Published: October 2009

Text-to-speech (TTS) technology imposes different constraints on intelligibility than those sufficient for the evaluation of other speech communication systems. For example, the newly revised standard S.2-2009 explicitly excludes TTS from the speech communication systems it covers. Since there is no current standard appropriate for evaluating TTS intelligibility, the ASA Standards Bioacoustics (S3) working group on Text-to-Speech Technology (WG91) was formed with the initial goal of developing such standard. We describe several ways in which standard methods of testing speech intelligibility are unsuitable for TTS technology and outline our approach to overcoming these limitations. We present an overview of our proposed standard, which is currently nearing its final draft stages.
Recombinant speech synthesis: Natural text-to-speech synthesis with prosodic control.
Authors: Klabbers Esther A. , Mishra Taniya , van Santen Jan P.H.
Published: October 2009

Unit selection text-to-speech synthesis methods rely on large corpora to cover all phoneme sequences in as many prosodic contexts as possible. This coverage is rarely complete except in limited domains. This becomes particularly salient when using prosodic markup to generate specific prosodic patterns (e.g., emphatic stress). An architecture is proposed combining the naturalness of unit-selection synthesis with the requirement of prosodic control. The speech corpus consists of multiple sub-corpora, each optimized to cover a “linguistic subspace”; subspaces include phoneme sequences, left-headed feet, sentence structures, and paralinguistic categories. The system relies on the superpositional model of intonation to decompose natural pitch contours into component contours, e.g., phrase curves (corresponding to phrases) and accent curves (corresponding to left-headed feet); on analogous methods for timing; and on hybridization methods to implement paralinguistic features. During synthesis, phoneme sequences, curves, and parameters are generated from the sub-corpora, optionally modified as per prosodic control tags, and “re-combined.” The explicit representation in terms of component curves allows for complete prosodic control, while the naturalness of the prosodic patterns is guaranteed by extracting these curves from natural speech and smoothly modifying them, thereby preserving important natural detail. [Research supported by NSF grant 0205731, “Prosody generation in child-oriented speech.”]
Wave propagation in phase-space.
Authors: Cohen Leon
Published: October 2009

We derive exact expressions for the spreading of a propagating pulse in a dispersive medium. We address both the deterministic and the random case, and also allow for the possibility of frequency-dependent attenuation. The conditions for contraction of a pulse before it eventually spreads to infinity are derived. In the interpretation of the expressions, we show that considerable insight may be achieved if the pulse is analyzed in phase-space where the phase-space distribution may be time-frequency or position-wavenumber. Applications to a train of pulses relevant to reverberation and clutter is also discussed. [Work supported by ONR 321US.]
Time-frequency analysis techniques for long range sediment tomography.
Authors: Potty Gopu R. , Miller James H.
Published: October 2009

Long range sediment tomography technique uses travel-time of acoustic normal modes at different frequencies to invert for the geoacoustic properties. The modal travel-times are calculated from the time-frequency analysis of the acoustic time series. Travel times in the frequency range 1 Hz to less than 1 kHz modes 1–6 obtained using broadband sources are typically used as data for the inversion. Various time-frequency analysis techniques used in the past in the context of long range sediment tomography will be presented. These techniques include short time Fourier transform, wavelet transform, matching pursuit algorithms, and dispersion based short time Fourier transforms. Performance of these techniques will be compared using data from various types of broadband sources deployed during different field experiments. [Work supported by Office of Naval Research.]
Using time corrected instantaneous frequency to detect source motion of a towed projector.
Authors: Shooter Jack A
Published: October 2009

The TCIF algorithm [S. Fulop and K. Fitz, J. Acoust. Soc. Am. 119, 360–371 (2006)] was applied to a narrow band projector from the Shallow Water 2006 Hudson Canyon experiment. To observe Doppler shifts near CPA, short overlapping FFTs were formed from the measured time series data. The appearance of a secondary Doppler component indicates that the source was wobbling or fishtailing during the tow event. Analysis indicated the source was moving back and forth with amplitudes of about 6 in., at a rate of 1–2 cycles/s. Detecting these source dynamics required a basic FFT length less than 18% of the variable period and signal-to-noise ratio greater than 18 dB. Narrowband filtering the data significantly reduced interference from outside the band of interest. The FFT lengths were so short the frequency bin spacing was much greater than the wobble frequency variation, yet TCIF permitted the source wobble period to be observed. [Work supported by IR&D.]
Blind deconvolution of quadratic time-frequency representations of musical signals for reverberation feature extraction.
Authors: Ren Gang , Bocko Mark F. , Headlam Dave
Published: October 2009

An acoustic space is uniquely characterized by its reverberant behavior. Due to the complexity of the multiple reflections and diffraction of sound in an enclosure, currently available system identification algorithms cannot effectively estimate the impulse response of a concert hall simply from musical recordings in that space. This paper reports the use of blind image deconvolution methods to construct echo patterns from quadratic time-frequency representations of reverberant recordings of music. First, a quadratic time-frequency analysis is performed to decompose the musical signal into its constituent harmonic components. Quadratic time-frequency analysis methods are known to give enhanced resolution in the time-frequency plane in comparison to conventional Fourier analysis. Reverberant features then appear as blur in the time-frequency plane, which can be estimated by employing the methods of blind deconvolution of this “image” of the sound. The proposed algorithm retrieves both the blur pattern, which corresponds to the reverberation echogram, and the direct acoustic signal. By choosing the time-frequency frame scale and smoothing window, a multi-resolution analysis of the underlying acoustic impulse response is obtained. Various quadratic time-frequency analysis methods are evaluated and their relative performance is reported. The proposed methods are also compared to existing dereverberation algorithms.
High-frequency broadband coherent reverberation predictions for the reverberation modeling workshop.
Authors: LePage Kevin D.
Published: October 2009

The reverberation modeling workshop included cases with strong attenuation to the forward propagation caused by multiple forward scattering. The effects of this attenuation were consolidated into effective reflection coefficients using the small slope approximation and provided to workshop participants. In this talk the coherent modeling of reverberation for these strongly attenuated cases using complex modes as computed by KRAKENC is described, and the results of these coherent modal predictions are compared to results obtained by other participants using ray theory. The importance of including both the complex mode shapes and eigenvalues, as well as the coherent interactions between modes, to obtain accurate predictions is discussed.
Emotion-related acoustic communication in bats.
Authors: Schmidt Sabine
Published: October 2009

Some features of emotional prosody in human speech may be rooted in mechanisms common to mammals. The role of vocal communication in social interactions was studied in bats, a highly vocal group evolutionarily remote from primates. The present paper focuses on communication during agonistic encounters in the Indian False Vampire bat. Three call types with distinct time-frequency contours occurred; aggression calls, whistles, and response calls. In a first experiment, agonistic approach situations were analyzed to assess the extent to which these call types reflected the specific part of the caller in the interaction and the intensity of the agonistic display. A frame-by-frame video analysis followed by a sound analysis revealed that call type indicated the part of the respective caller while interaction intensity was encoded in similar parameter changes across call types. The systematic change in vocal parameters with affect intensity corresponded to prosodic changes in human speech. A playback experiment based on a habituation-dishabituation paradigm investigated how the bats categorized the vocalizations emitted during third-party agonistic interactions. The bats were able to discriminate between call types; however, they did not necessarily form categories corresponding to call type in reciprocal experiments, an evidence for a context-dependent evaluation of social calls.
Vocal production, affect expression, and communicative function in African elephant rumble vocalizations.
Authors: Soltis Joseph
Published: October 2009

African elephant rumbles are harmonically rich vocalizations with clear formant structure. The low-frequency, high amplitude nature of rumbles is consistent with the observed large vocal production anatomy. Examination of formant locations and inter-formant dispersion implicates the trunk in addition to the oral cavity in rumble production. Adult female African elephants express affect intensity in ways similar to other mammals. When interacting with social superiors, subordinate rumbles exhibited increased and more variable fundamental frequencies, and increased amplitudes and durations, compared to periods of social calm. Filter features did not change across behavioral contexts. Acoustic responses originally related solely to affect may come to serve communicative functions. During dyadic approaches by adult females, rumbles resembling the “fear response” of subordinates (i.e., those with increased durations and more variable fundamental frequencies) increased the likelihood of friendly social interaction, and these signals were produced by both subordinate and dominant animals. Two top-ranking females were co-dominant and competed for alpha status. When interacting with each other, they produced rumbles with decreased fundamental frequencies, increased amplitudes and durations, and a decrease in inter-formant dispersion. This acoustic response is not generally consistent with the expression of affect but may signal large body size to social competitors.
Affect cues in communication calls of tree shrews.
Authors: Zimmermann Elke
Published: October 2009

Comparative studies on affective prosody in human speech revealed remarkable cross-cultural similarities suggesting that affective prosody may have originated from a prehuman basis. To explore this hypothesis, the acoustic variation in communication calls and its perception in tree shrews were examined. Tree shrews are small diurnal mammals, genetically closely related to primates, living in dispersed pairs in the dense tropical forests of south-east Asia. Calls were induced experimentally in a social encounter and a disturbance paradigm, respectively, and related to two behaviorally defined arousal states within specific behavioral contexts. Context and arousal state of the caller reliably predicted spectral and temporal variations in call structure. Whereas context is closely associated with the frequency-time contour of calls (call type), arousal is expressed in shifts of fundamental frequency and the rate of call production. In a habituation-dishabituation paradigm, testing the effect of arousal-related variation within the same call type, tree shrews were able to discriminate acoustically between two arousal states. All in all, these findings document the relevance of affect cues in the vocal communication system of a non-primate mammal, the tree shrew, and support that mechanisms involved in the acoustical expression and perception of emotions are deeply rooted in mammals. [Work supported by DFG FOR 499.]
Infant mouse isolation ultrasounds: Production, perception and neural plasticity.
Authors: Liu Robert C
Published: October 2009

Mouse pups emit ultrasonic whistles when they are isolated from their nest, likely reflecting an increased state of arousal that may be modulated by emotional and motivational processes [G. Ehret, Behav. Genet. 35, 19–29 (2005)]. Mouse mothers recognize the behavioral relevance of these calls and search out these pups to retrieve them to the nest. On the other hand, pup-naive virgin females do not prefer to approach these calls over a neutral sound, suggesting they do not recognize their significance. Whether this difference in recognition correlates with any changes in how the auditory system processes these vocalizations is being investigated. Evidence from electrophysiological recordings in the auditory cortex of both anesthetized and awake female mice demonstrate that the cortical activity evoked by natural ultrasonic calls is changed in a way that could functionally improve the ability to detect and discriminate them. These results indicate that irrespective of a possible difference between virgins and mothers in the neural circuitry for deciding to respond to pup calls, the sensory system itself is plastic in its representation of these vocalizations.
About phonetic and perceptual similarities in laughing, smiling, and crying speech.
Authors: Erickson Donna , Menezes Caroline , Sakakibara Ken-ichi
Published: October 2009

Acoustic, articulatory (EMA), and perceptual characteristics of recordings of spontaneous happy laughing/smiling, sad crying, and neutral speech were examined. Listeners were asked to (1) rate the emotional intensity of the speech and (2) categorize it as happy, sad, not-emotional, unknown, or other. Results show distinctive acoustic, articulatory, and perceptual characteristics for listeners’ ratings of “emotional” versus “not-emotional” speech. Emotional speech has significantly higher F0, higher F2, lower H2, raised/retracted upper lip, and lowered tongue. Between happy laughing/smiling speech and sad crying speech, phonetic and perceptual similarities were observed, with mismatches between the emotion intended by the speaker and that perceived by listeners. The results of this study highlight how underlying emotions interact with temporal emotion in a complex way, affecting the perception of emotion. Laughing and crying to bring about a type of catharsis or balance to the system are also discussed. [This work was supported in part by Japanese Ministry of Education, Science, Sport, and Culture, Grant-in-Aid for Scientific Research (C), (2007–2010):19520371 and SCOPE (071705001) of Ministry of Internal Affairs and Communications (MIC), Japan.]
A computational assessment of the sensitivity of ambient noise level to ocean acidification.
Authors: Joseph John E , Chiu Ching-Sang
Published: October 2009

Low-frequency (<2 kHz) sound propagating through the ocean is attenuated by the pH-dependent boric acid chemical relaxation process. This well-studied process shows that lower seawater pH results in lower sound attenuation at low frequencies. Thus, the uptake of anthropogenic CO2 by seawater, leading to ocean acidification and lowering pH of seawater, has potential to change ambient noise levels. An important question is: By how much? Here, changes in ambient noise level due to theoretical changes in seawater pH have been calculated at three different locations, the Pacific, Atlantic, and Arctic oceans, using a hypothetical spatial distribution of pH based on the literature and forecasted to the year 2100 [Cao et al., (2007); McNeil and Matear, (2006)]. A range-dependent acoustic model has been applied using sound speed and winds based on climatology, and a historical shipping database to make ambient noise level predictions. Results of our model calculations are presented and discussed.
Sound absorption and pH quantification in the presence of signal fluctuations.
Authors: Duda Timothy F.
Published: October 2009

The technique of using differential sound attenuation over a known path in two or more frequency bands to measure pH-dependent sound absorption effects, and by extension integrated ocean pH, was introduced in the 1980s by Jin and Worcester. The method is complicated by the fact that the mean levels of fluctuating signals with additive noise must be determined. The gain of the measurement increases with propagation distance because absorption (attenuation) accumulates with distance, but fluctuations tend to also increase with distance, and signal to noise ratio decreases, inhibiting the measurement. The fluctuation effects dominate. Utilizing intensity fluctuation data (from long-range experiments of recent decades) plus estimated signal and noise levels, the quantity of independent differential attenuation data points needed (N) to make measurement (pH accuracy of 0.05) is estimated and presented, as a function of center frequency, band separation, and propagation distance. One such estimate is N=500 for 450-Hz, 200-Hz band separation, 700 km. Reducing to 100-Hz separation quadruples N for a given distance and center frequency. Increasing distance slightly increases N and shifts the optimal frequency (least N required) downward, while reducing it has the opposite effect.
A low-frequency array system for transcranial foreign body detection.
Authors: Farny Caleb H. , Tang Sai Chun , Clement Greg T.
Published: October 2009

There has been recent interest in developing portable devices for advanced battlefield regions to detect foreign bodies that have penetrated the skull. Here we present on a compact ultrasound array system for transcranial detection of foreign bodies embedded in a tissue-mimicking phantom. The system is designed to be powered from a laptop via USB and present information regarding the presence of foreign targets within the skull. Design parameters investigated the influence of transducer center frequency and diameter, with particular importance placed on minimizing the number of transducers employed in the array for weight reduction. Frequencies ranging from 320 to 800 kHz were examined as well as the tradeoff between longitudinal and shear mode propagations through the skull bone layer. Ex vivo human calvaria were used to mimic application conditions. Measurement consisted of successive excitation of each transducer in the array by a three-cycle bipolar pulse from a single-channel multiplex pulse-receive system, and the scattered signal was successively received by each transducer in the array. The maximum volume of interrogation and resolution of detection relative to the skull bone were determined from placement of stainless steel and ceramic targets embedded in the phantom positioned inside the skull. [Work supported by USAMRMC:NPI-0704-00710.]
In vivo imaging of developing mouse embryos using a high-frequency annular-array and chirp-coded excitation.
Authors: Mamou Jonathan , Ketterling Jeffrey A. , Aristizábal Orlando , Turnbull Daniel H.
Published: October 2009

High-frequency ultrasound (HFU) offers great potential for in vivo imaging of developing mouse embryos. Nevertheless, mouse-embryo imaging remains challenging because of the random orientation of the embryos and of the limited acoustic penetration depth of HFU. In this study, a 34-MHz, five-element annular array was excited using conventional mono-cycle and chirp-coded excitations. Synthetic focusing and pulse compression (for the chirp excitation) were used to form images with increased depth of field and penetration depth (for the chirp excitation). Three-dimensional (3-D) datasets were acquired from 11-, 12-, and 13-day-old mouse-embryo heads using both excitation schemes and a respiratory-gating algorithm that limited motion artifacts. 3-D reconstructions of the brain ventricles were formed and compared to MRI-based reconstructions. The chirp-based reconstructions were more morphologically accurate than the mono-cycle-based reconstructions. Furthermore, only chirp datasets provided sufficient penetration depth to correctly segment the brain ventricles lying deep inside the mother. Differences between the calculated brain-ventricle volumes obtained using chirp and mono-cycle excitations were as high as 80%. The results of this study suggest that high-frequency chirp-annular-array imaging could become a valuable tool for translational studies and non-invasive efficient phenotyping of the early mouse central nervous system. [Work supported by NIH Grants EB006509 and EB008606.]
Shannon entropy can detect myocardial anisotropy without specular echo gating in vitro.
Authors: Cheng Ya-Jian , Hughes Michael S. , Marsh Jon N. , Wallace Kirk D. , Wickline Samuel A.
Published: October 2009

Ultrasonic images are often corrupted by specular echoes that obscure features near interfacial boundaries. This problem can be especially severe for in vitro examination of excised tissues (e.g., myocardium) which must often be sliced into thin sections to permit examination by other techniques in addition to ultrasound (e.g., optical, MRI, and histology), in order to characterize infarct region size and myofiber orientation. In many of these studies, myocardial anisotropy is obscured without removal of specular echoes by gating. Here, it is demonstrated that entropy imaging enables visualization of myocardial anisotropy without gating. Short axis slice of mouse heart (n=4) was C-scanned on a 55×55 grid, with 0.1 mm stepsize. At each point one 8-bit, 2048 point, time-averaged A-line was acquired. These were analyzed using three signal receivers, log variance, log energy (sum of squared), and Shannon entropy, to produce one pixel value at each location in the C-scan. Diffusion-tensor-weighted magnetic resonance at 12 T was used to validate the ultrasonic result. Among the three signal receivers, only entropy clearly resolves myocardial anisotropy without specular echo removal. [This work supported by NIH CA119342, and NSC-095-SAF-I-564-051-TMS.]
Assessment of shear elasticity and viscosity of tissue using acoustic radiation force applied to a spherical acoustic inhomogeneity.
Authors: Karpiouk Andrei B. , Aglyamov Salavat R. , Emelianov Stanislav Y.
Published: October 2009

An accurate assessment of mechanical properties of tissue is desired in many applications ranging from biomedical research to medical diagnostics and surgery. Currently, several methods to assess shear elasticity of tissue are available while the techniques to measure tissue viscosity are not yet fully developed. However, shear viscosity is an indicative functional parameter of soft tissue. In addition, the local changes of shear viscosity can affect the accuracy of shear elasticity assessment. Therefore, in this study, an acoustic radiation force approach to assess both shear elasticity and viscosity of tissue is developed. Such approach is based on monitoring of the spatio-temporal displacement of an ultrasound inhomogeneity in response to applied impulsive radiation force. In experiments, a 2-mm-diameter solid sphere was embedded into the gel phantoms with varying shear elasticity and viscosity. The sphere was then perturbed using acoustic radiation force produced by a single-element focused ultrasound transducer operating at 3.5 MHz. The displacement of the sphere was monitored using another single-element focused ultrasound transducer with center frequency of 25 MHz. The results indicate that the temporal characteristics of the displacement can be used to assess both shear elasticity and viscosity of tissues simultaneously and independently. [Work supported by NIH.]
Vibrational modes of accordion reeds.
Authors: Behrens Sarah L. , Coyle Whitney L. , Goodweiler Nicholas P. , Cottingham James P.
Published: October 2009

Some new measurements made of the oscillation of air-driven accordion reeds show that higher transverse modes through the fourth mode are present as well as the first torsional mode. The second and third transverse modes are observable even at low amplitudes of oscillation. All of these have been previously observed in reed organ reeds [Paquette et al., J. Acoust. Soc. Am. 114, 2348 (2003)]. Additionally, for the first time a lateral mode of vibration (transverse vibration perpendicular to the usual first transverse mode) has been observed. For airflow in a given direction, only one of the two reeds mounted in each wind chamber is the primary source of sound production, but the vibration of the secondary reed has also been studied. The amplitudes of higher-frequency modes relative to the fundamental are observed to be higher in the secondary reed than in the primary reed. Finite element calculations of the reed modes have been made, and the calculated mode frequencies and node locations were used to verify mode identification. [Work partially supported by National Science Foundation REU Grant No. PHY-0354058.]
Accordion reeds, cavity resonance, and pitch bend.
Authors: Tonon Thomas
Published: October 2009

In keyed free reed instruments such as accordions and concertinas, the reeds are mounted over cavities that have little effect on the vibration of the reed itself, because resonances between the reed and cavity are rarely encountered. In fact, in conventional instruments, resonances can interfere with the self-excitation mechanism of the reed and become problematic to the builder. On the other hand, one can exploit such resonances in order to produce pitch bend and other acoustic effects, by intentionally designing the cavity for near resonance and by providing a mechanism that permits the musician to engage resonance at will. First, conventionally designed cavity resonance is investigated over the frequency range of the instrument, illustrating the thoroughness and facility with which cavity resonance can be designed out of conventional instruments. Finally, cavity designs and linkage mechanisms to exploit desirable acoustic effects of cavity resonance are illustrated.
Mitigating existing mechanical noise in a new state-of-the-art Indoor Training Center for University of Washington Golf.
Authors: Wiebusch Julie A.
Published: October 2009

For several years, excessive mechanical noise levels had rendered the “multi-purpose room” in the UW Hec Edmundson Pavilion virtually unusable by every athletic department. Adjacent to a mechanical room and separated only by a pair of poorly sealed doors, the room served as the main pathway for all ductwork from the mechanical room to other areas in the building. In addition, a large duct branched off of the main duct and ran vertically along one wall to exhaust the locker rooms below. The vertical portion of this duct had been partially enclosed in a gypsum board chase, which was making contact with the ductwork. The vibrational energy was re-radiated as airborne sound, emitting a low-frequency rumble throughout the space. Background noise levels were measured in excess of 70 dBA and NC 67. The space was offered to the Men’s and Women’s Golf Teams for their new Indoor Training Facility. This case study presents the mitigation techniques used to reduce noise levels to allow the room to be transformed into a cutting edge training facility.
Evaluation of hydraulic silencers.
Authors: Earnhart Nicholas E. , Marek Kenneth A. , Cunefare Kenneth A.
Published: October 2009

Hydraulic silencers are devices used to mitigate fluid-borne noise in fluid power systems. Fluid-borne noise may be produced by positive-displacement pumps and interacts with system components to generate vibration and air-borne noise. It is of interest to quantify the performance of silencers with regard to the input reflection coefficient and transmission loss. A test rig has been constructed that uses a six-sensor method to determine these quantities. Construction and methodology will be presented along with results for a commercially available silencer.
Improvement of vowel formant discrimination: Effects of global and local enhancement.
Authors: Woodall Ashley , Liu Chang
Published: October 2009

Vowel formant discrimination measures the smallest change in vowel formant frequency that is detectable. Thresholds of vowel formant discrimination were examined for F2 frequency of three American English vowels on normal-hearing and hearing-impaired listeners. Vowel stimuli were manipulated with a global enhancement by increasing speech level from 70- to 90-dB SPL and a local enhancement by increasing F2 amplitudes of 3, 6, and 9 dB. For each listener, vowel formant discrimination was tested for six sets of stimuli (3 local F2 enhancement × 2 global enhancement). Results showed that both normal-hearing and hearing-impaired listeners significantly benefited from local enhancement and local plus global enhancement, but not from global enhancement only. In addition, the improvement in vowel formant discrimination for hearing-impaired listeners was substantially higher than for normal-hearing listeners. However, given the same formant structure (original or enhanced F2), normal-hearing listeners did not receive any benefit from increasing the global level from 70- to 90-dB SPL. On the other hand, hearing-impaired listeners improved their thresholds from 70- to 90-dB SPL, but only when enhanced F2 was presented. There results indicate that, to improve vowel formant discrimination, local enhancement of target formant amplitude is more important than global enhancement.
Testing the limits: Quantifying the degradation of automatic speech recognition in reverberant environments.
Authors: Secules Stephen , Braasch Jonas
Published: October 2009

Surprisingly little is known about the specific character of the depreciation of automatic speech recognition in reverberation—its primary acoustics causes (e.g., room geometry and reverberation strength) or speech effects (blurring of syllables, plosives, and consonants). The focus of this study is to precisely quantify the depreciation of speech recognition accuracy for reverberant signals using a black box experiment to vary reverberation characteristics and observe speech recognition accuracy. The methodology tests two speech recognition platforms on a recognition task of similar sounding word lists. A range of reverberant settings was simulated by convolution with an impulse response. The recognizers had the least reverberant recognition accuracy for words which only differed by their ending consonants. The depreciation of recognition accuracy from early reflections alone was lower than the overall room effect; however, the overall depreciation with respect to the absorption coefficient was well predicted by the strength of the reverberant tail. The results were compared to the results of prior research.
Robert T. Beyer: A sustained record of distinguished service to the profession.
Authors: Pierce Allan D.
Published: October 2009

A historical and anecdotal account is given of Robert T. Beyer’s professional service. Highlights include his service to the Acoustical Society as Member of the Executive Council (1956–1959), Vice-President (1961–1962), Chair of the Physical Acoustics Technical Committee (1963–1964), President-Elect (1967–1968), President (1968–1969), and Treasurer (1974–1994). He was Chair of the Investments Committee (1990–1992) and served as an Associate Editor of the Journal for three distinct terms: 1952–1955 (References), 1965–1969 (Acoustical News from Abroad), and 1985–1991 (Book Reviews). He also served as interim Editor-in-Chief after the death of Robert B. Lindsay in 1985. Beyer was a voracious reader, an indefatigable translator, and a prolific writer. He wrote several textbooks, numerous book reviews, and frequent reports in JASA on the finances of the Society. His activities as a translator and editor of translated journals are legendary. Beyer’s connections with the American Institute of Physics include Board of Governors (1969), Member of Executive Committee of Board (1974), Member of Translation Advisory Board (1955–1978) and its Chairman (1957–1977), and Board of Translations Editors (1978). The ASA awarded Beyer its Distinguished Service Citation in 1978, but he undoubtedly did enough more between 1978 and 2008 to justify being awarded several additional Service Citations.
Beyer’s legacy in determination of nonlinear acoustic parameters.
Authors: Everbach E. Carr
Published: October 2009

Beyer’s classic 1974 text Nonlinear Acoustics, which was first published in 1976 and was later reprinted in 1994, provided the pedagogical foundation for generations of productive acoustics work. This talk will focus on Beyer’s contributions to the theory and measurement of acoustic nonlinearity parameters, and on the later research that grew out of it, especially efforts to quantify and employ the acoustic nonlinear parameter B/A in innovative imaging strategies.
VOICESAUCE: A program for voice analysis.
Authors: Shue Yen-Liang , Keating Patricia , Vicenik Chad
Published: October 2009

VOICESAUCE is a new application, implemented in MATLAB, which provides automated voice measurements over time from audio recordings. The measures currently computed are F0, H1(*), H2(*), H4(*), H1(*)-H2(*), H2(*)-H4(*), H1(*)-A1, H1(*)-A2, H1(*)-A3, energy, Cepstral Peak Prominence, F1–F4, and B1–B4, where (*) indicates that harmonic amplitudes are reported with and without corrections for formant frequencies and bandwidths [Iseli et al. (2006)]. Formant values are calculated using the Snack Sound Toolkit, while F0 is calculated using the STRAIGHT algorithm; harmonic spectra magnitudes are computed pitch-synchronously. VOICESAUCE takes as input a folder of wav files, and for each input wav file produces a MATLAB file with values every millsecond for all measures. It can operate over the whole input file or over segments delimited by a PRAAT textgrid file. VOICESAUCE then takes these MATLAB outputs, optionally along with electroglottographic measurements obtained separately from PCQUIRERX, and provides condensed outputs in text format; alternatively it can write the MATLAB outputs to the format used by the Emu Speech Database system. We compare results of VOICESAUCE analysis with manual measurements from FFT spectra and with measurements from a PRAAT script. [Work supported by NSF.]
Voice quality and emotion classification on the valence scale.
Authors: Choi Ka Won , Choi Jeung-Yoon
Published: October 2009

While discriminating between several basic human emotions, such as neutral, joy, sadness, and anger, it has been observed that the most difficult emotions to tell apart automatically are between the two states of joy and anger. Since these two emotions have similarities on the arousal scale, it is difficult to distinguish them by simply using pitch and energy related feature measurements. Therefore, in this study, other additional feature parameters, related to voice quality, that are useful for discriminating between the two emotions of joy and anger are focused. For voice quality related features, global statistics of normalized spectral band energy, spectral tilt, open quotient, and first formant bandwidth values, along with their respective slopes and convexities, are measured from the happy and angry emotional speech from a Korean emotional database. From ANOVAtests, parameters of normalized spectral band energy, spectral tilt, and open quotient appear to be useful. Also, slopes and convexities of voice quality measurements appear to be more important than the values itself. These results are meaningful for classifying emotional states distributed on the valence scale and are expected to contribute in improving an overall emotion recognition system.
Finding prosodic events using voice source measurements over multiple syllables.
Authors: Han Ran , Choi Jeung-Yoon
Published: October 2009

Voice source measurements such as slope and convexity of pitch, harmonic structure, spectral tilt, and amplitude have been shown to be closely correlated with prosodic events, and using these measurements over multiple syllables has been shown to produce better performance than using measurements taken over a single syllable. In this study, these measurements for specific prosodic events, namely, for nine types of accents are more closed examined, observed in the Boston University Radio Speech Corpus. Examination of distributions of these measurements at various accent levels shows that the presence of a high accent is correlated with less negative slopes of these measurements and a low accent is correlated with more negative slopes. From ANOVA tests, analyses show that several measurements yield high significance in distinguishing among accent levels. This study also includes an examination of the distributions of these measurements across boundary levels, and results show that voice source measurements are useful in distinguishing among the various accent levels in prosody.
Aeroacoustics of voiceless fricatives: An in-vitro investigation on simplified vocal tract geometries.
Authors: Estienne Olivier , Van Hirtum Annemie , Bailliet Hélène , Pelorson Xavier
Published: October 2009

Production of fricatives consonants is a complex aeroacoustical problem involving the interaction of turbulent airflow with the particular geometry of the vocal tract. The current study introduces a simplified mechanical static vocal tract including a tongue replica and a rectangular thin obstacle downstream of the constriction formed by the tongue and the upper tract wall. First, pressure of the vocal tract flow and far-field noise are measured for different entrance volume velocities, longitudinal tongue positions, and obstacle heights. Changing the geometrical parameters induces spectral noticeable changes and, particulary, when the ratio obstacle height/tract height is close to 1, spectra are shaped like those of sibilant fricatives. Next, velocity-turbulence measurements in the same conditions by means of hot film anemometry are realized, which permits to find relations between aerodynamics and previous acoustical observations. It will also complete pressure data for the validation of future vocal tract flow models, which could serve for fricatives synthesis applications.
Auditory feedback and articulatory timing.
Authors: Mitsuya Takashi , MacDonald Ewen N. , Munhall Kevin G.
Published: October 2009

Talkers listen to their own voice while they speak and use that feedback to monitor and control fine details of speech production. When auditory feedback is perturbed in real time, talkers spontaneously alter their speech production to compensate for the perturbation. Most research using real-time altered auditory feedback has focused on spectral manipulations of vowels with little attention devoted to temporal manipulations of consonants. In the present study, we examine the role of acoustic feedback in control of voice onset time (VOT). Utterances of the words “tip” and “dip” were recorded from native English speakers, and several representative productions were selected for each speaker. After this, talkers were asked to repeatedly produce either tip or dip. During these productions a real-time processing system was used to provide modified feedback through headphones. When talkers said one word, they simultaneously heard their own voice saying the other word. Results showed that the speakers compensated for the VOT perturbation such that they lengthened their VOT for /t/ when the VOT of the feedback was shorter (/d/). Based on these results, a comparison of the role of auditory feedback in controlling temporal and spectral aspects of speech production will be discussed.
Spectral roughness inferred from measured reverberation time series.
Authors: Stotts Steven A. , Koch Robert A.
Published: October 2009

Reverberation data are often interpreted in terms of either Lambert’s law or a scattering kernel representation with a specified roughness spectrum. The parameters in these descriptions are adjusted and combined with a propagation model to produce simulated reverberation time series that fit the data. An alternative is to retain the scattering description with two separable factors: a well-defined physics-based vertical angle factor that can be justified analytically and a roughness spectrum factor that is adjusted to reproduce the measured data. For this purpose the scattering description is based on a two-way coupled-mode formalism that was shown to accurately produce reverberation time series for a two-dimensional, rough-bottom Pekeris waveguide [Knobles, Reverberation Workshop I, Austin, TX (November 2006)]. For water-sediment interface scattering, the off-diagonal components of the vertical angle factor in the Born approximation were shown to be equivalent to the kernel adopted by the Reverberation Workshop [Stotts and Koch, JASA Exp. Lett., EL242–EL248 (2008)]. Examples from the Reverberation Workshop problem sets will be used to demonstrate the fitting process for specific roughness spectra.
Prediction of clutter on the Malta Plateau.
Authors: Nielsen P. L. , Prior M. , Harrison C.
Published: October 2009

NURC has conducted a series of experiments on the Malta Plateau, Mediterranean Sea, with the focus on collecting environmental and acoustic clutter data. Strong correlation between the environmental and processed acoustic data has been established for certain regions which provides important information to enhance prediction capabilities and signal processing algorithms and to eventually reduce the clutter returns in the sonar processing chain. However, strong clutter-like returns are persistently observed from a confined location on the Plateau with no clear indication of significant scattering features, i.e., no evidence of bathymetric features, variations in sub-bottom stratification, or changes in bottom geoacoustic properties. Only the sub-bottom profiling shows inclusions in the upper 5 m of the sediment, and these inclusions are hypothesized to have slightly different geoacoustic properties than the surrounding. This hypothesis is presented and verified by backscattered time-series computations using a two-way prediction model applied in an environment similar to that of the acquired acoustic data. [Work supported by the NATO Undersea Research Centre, the CLUTTER JRP partners, and the Office of Naval Research OA321.]
Acoustical education in architecture.
Authors: Siebein Gary, W.
Published: October 2009

Sound can provide valuable contributions to the education and practice of architecture. First, architecture students should develop a theory of how sound and other environmental systems can become part of a larger theory of the making of architecture. Second, architects are trained to have highly developed sensibilities in the aesthetic design of space. Expanding the aesthetic component of buildings and environments to include the aural environment has the potential to enrich the fabric of communities and buildings. Third, architecture students must become acquainted with the materials, analytic techniques, and design approaches that acoustical consultants use. Furthermore, for acoustical information to become an integral part of architectural design and education, it must be organized in a way that allows expression or poesis to occur because these aesthetic principles are the building blocks of architectural design. Therefore, the science and engineering principles of noise control and architectural acoustics must be transformed into material that can become spatial, visual, and manipulable in creative ways by a design team. This requires that the basics of acoustics be reformulated in an architectural manner. This paper will address several of the transformations that have been attempted in the architectural acoustics curriculum at the University of Florida.
A broad education in acoustics still makes sense.
Authors: Sparrow Victor W. , Brooks Karen P.
Published: October 2009

For students preparing for a career in acoustical consulting, or for professionals thrust into job duties involving acoustics but without formal training, there is much to be gained by obtaining a broad education in acoustics, vibration, noise control, transducers, and signal processing. For the graduating student or the professional changing jobs, a broad education helps ensure that they will be adequately prepared for whatever they will face. Equipment and computer programs will come and go over time, but the ability to think clearly, solve problems, and understand important fundamental physical phenomena never goes out of style. At the Graduate Program in Acoustics at Penn State, our focus relies on a core curriculum that forms a solid foundation. Residence classes are currently blended (co-presented) for participation by students at a distance anywhere in the world using ADOBE CONNECT software and Smartboard presentation hardware. Distance students and guest presenters, e.g., practicing consultants, can also link in, making live presentations to everyone in the class. There is no reason why anyone with an internet connection and sufficient math and physics background cannot gain a broad education in acoustics to last a lifetime.