bluuebunny/crossref_metadata_2025 huggingface dataset:
The behavior of the distortion product otoacoustic emissions in response to contralateral stimulation by stationary and nonstationary signals
Authors: Szczepaniak Olimpia
Published: October 2013

The main aim of the study was to determine the DPOAE of the cochlea in the case of contralateral stimulation by stationary and nonstationary signals. The analysis was performed for 3f1−2f2, 2f1−f2, 2f2−f1 intermodulation distortion products on a group of 20 normal hearing subjects (NH) and ten patients with low UCL (uncomfortable loudness level). The optimized primary tone level setting (L1=0.4L2+39 dB) was used. Each NH subject was characterized by the I/O function of otoacoustic emission (40–90 dB SPL) and dp-grams for the three levels of two-tone (85/75, 75/65, and 65/55 dB SPL) for frequencies between 1 and 12 kHz. Parameters for subjects with UCL were individually selected. The suppression of otoacoustic distortion products and the intergroup correlation of the slopes of I/O function with various contralateral stimulators were discussed. Results obtained from the experiment were compared between the two groups studied.
A functional MRI study on auditory feedback control of pitch
Authors: Toyomura Akira , Koyama Sachiko , Miyamoto Tamaki , Terao Atsushi , Omori Takashi , Murohashi Harumitsu , Kuriki Shinya
Published: October 2013

Perception of one’s own speech plays an important role in fluent speech production. In this study, we conducted a functional magnetic resonance imaging (fMRI) experiment to delineate the neural mechanism for auditory feedback control of pitch, using a transformed auditory feedback (TAF) method. Subjects (n=12, right handed) were required to vocalize /a/ for 5 s while hearing their voice through a headphone. In the TAF condition, the feedback voice pitch was shifted randomly up or down from the original pitch two or three times. The subjects were required to hold the pitch of the feedback voice constant by changing the pitch of the original voice. In the non-TAF condition, the pitch of feedback voice was not modulated and the subjects merely vocalized /a/ continuously. A contrast between TAF and non-TAF conditions showed some significantly greater activations in the TAF condition (p<0.05 corrected). In the right hemisphere, the supramarginal gyrus, the prefrontal area, the anterior insula, and the superior temporal gyrus showed greater activation. In the left hemisphere, only the premotor area showed greater activation. This result suggests that auditory feedback of pitch is controlled mainly by the right hemispheric network. [Work supported by JST.]
Mechanisms of bone-conducted ultrasonic perception assessed by electrophysiological measurements in human
Authors: Nakagawa Seiji , Nakagawa Aya
Published: October 2013

Several studies have reported that bone-conducted ultrasound (BCU) is perceived even by the profoundly sensorineural deaf; however, the mechanisms involved remain unclear. We previously reported some unique characteristics of BCU perception: (1) the pitch of BCU is about ten-odd kHz and is independent of its frequency, (2) the dynamic range of BCU is narrow, less than 20 dB, and (3) BCU mask 10–15-kHz air-conducted sounds. In this study, cortical magnetic field (N1m), middle latency (MLRs) and auditory brainstem responses (ABRs) and electrocochleogram (EcochG) evoked by BCU in human were recorded to clarify the neural pathway for BCU. Substantial MLRs and ABRs (wave-I–V) were evoked by BCU as well as by air-conducted sound. Although a clear N1m response was elicited by BCU and its equivalent current dipoles (ECDs) were estimated in the auditory cortices, ECD locations for BCU did not follow the tonotopic organization at the cortical level. Both wave I of ABRs and AP of EcochG were observed clearly, indicating that the auditory nerve was substantially activated. These results suggest that BCU goes through the normal auditory pathway—there are no special organs for BCU perception; however, unique processes may exist in the cochlea.
Interaction between the tonotopic and periodic information in recognition of ‘‘melodic’’ contours
Authors: Matsui Toshie , Takeshima Chihiro , Tsuzaki Minoru
Published: October 2013

It is known that the tonotopic and periodic aspects of sounds are separated in the auditory sense. To investigate the manner of representing these two aspects, a psychological experiment was designed. The stimuli are sequences of vowels, each of which changes its fundamental frequency and ‘‘size,’’ i.e., the centroid of its formants, using a STRAIGHT vocoder. Participants are asked to respond if the transient patterns of the stimuli are ‘‘clockwise’’ or ‘‘counterclockwise’’ in a two-dimensional space, one of whose coordinates is the periodicity and the other of which is the size. Results indicate that the judgment was not so easy as in the case in which one would judge the transition patterns of points in a two-dimensional visual space. This inference implies that the two attributes might be represented as values on two completely independent scales, but not like the values in two coordinates of a single point.
A preliminary study of construction of a musical mood scale
Authors: Matsumoto Junko
Published: October 2013

In this study to construct a mood scale that was specific to listening to music, appropriate items were selected preliminarily. Three hundred three university students were presented 70 adjectives by a questionnaire and asked to rate how frequent they feel each mood after listening to music in their daily lives on a four-point scale. A factor analysis were completed on the mood items and yielded five factors indicating suffering, comfortableness, solemnness and aggression, calmness, and sadness, respectively. Items with high loading on these factors were selected to construct a musical mood scale and any of them were modified because they might have an obscure meaning.
Sensitivity analysis to evaluate the benefits and risks of using prior information in adaptive psychometric procedures
Authors: Remus Jeremiah , Collins Leslie
Published: October 2013

Numerous adaptive psychometric procedures have been developed based on a Bayesian framework. In these procedures, a key component for estimating the targeted parameter and determining the next stimulus value is the parameter probability distribution. The presence of a parameter probability distribution introduces the opportunity to include prior information via initialization of the parameter probabilities. However, differences in the techniques for parameter estimation and stimulus selection may determine how various psychometric procedures benefit from accurate prior information or recover from inaccurate prior information. In this study, several adaptive psychometric procedures using a Bayesian framework were investigated through simulation of a psychophysical task. The simulations included prior information with varying degrees of accuracy and varying levels of initial confidence. Results suggest that the benefits of prior information are dependent on the specific psychometric procedure and the inclusion of prior information may influence the final choice of an appropriate psychometric procedure.
Observed variability in d′ for yes-no and two-interval forced choice procedures
Authors: Jesteadt Walt , Leibold Lori , Khaddam Samar , Messersmith Jessica , Krivohlavek Melissa
Published: October 2013

The sampling distribution of d′ estimates can be determined from knowledge of the true d′ and the number of trials per estimate [J. Miller, Percept. Psychophys. 58, 65–72 (1996)]. Five subjects were tested in a fixed-level intensity discrimination task to obtain estimates of the observed variance of d′ for both the yes-no and two-interval forced-choice (2IFC) procedures over a wide range of d′ values. The stimuli were 2-kHz sinusoids, 300 ms in duration with 10-ms ramps, with differences in intensity ranging from 0.1 to 4.9 dB, centered on 70 dB SPL. An estimate of d′ was computed for each of ten 100-trial blocks at each intensity difference for each procedure. Psychometric functions, based on 14000 trials per function, were well fitted using intensity differences expressed in units of ΔL and were steeper for 2IFC than for yes-no. The variance of d′ estimates exceeded the variance of the sampling distribution by a factor of 2.1 for yes-no and a factor of 3.1 for 2IFC, with learning effects contributing to the additional variance in some subjects. For a given value of d′, the variance of d′ estimates was approximately equal in yes-no and 2IFC. [Work supported by NIH/NIDCD.]
Remote psychoacoustic testing using the Internet
Authors: Disley Alastair C. , Howard David M. , Hunt Andrew D.
Published: October 2013

A number of recent listening tests by the authors and others have begun to use the Internet as a medium for remotely conducting psychoacoustic listening tests. While this offers a solution to the problem of gathering enough highly trained listeners in one geographic location, it results in a reduction in control of factors such as the listener’s immediate environment. A recent experiment by the authors [A. C. Disley, et al., ‘‘Spectral correlations of timbral adjectives used by musicians,’’ J. Acoust. Soc. Am. 119, 3333 abstract only (2006)] offered the opportunity to examine and quantify the effect of remote testing via the Internet. Twenty four listeners took an Internet-based listening test on ten separate occasions, alternating between a controlled environment and an uncontrolled environment. Listeners were given instructions about their uncontrolled listening environments, and data subsequently collected demonstrate good but not universal compliance with those instructions. Comparison of experimental results between the different test environments shows very little difference, with a slight reduction in the controlled environment to the listeners’ self-assessed confidence in their judgments. The techniques, advantages, and disadvantages of the Internet as a medium for remote psychoacoustic testing are discussed.
+Gz acceleration modifies low-frequency perception
Authors: Sandor Patrick M. B. , Pellieux Lionel , Dehlinger Christophe
Published: October 2013

Hypergravity is associated with maneuvering acceleration (+Gz) in fighter aircraft and can be simulated in a human centrifuge, two noisy environments where classical audiometric data in silence cannot be obtained. Yet under +4-Gz acceleration, with masking noise, the hearing threshold just superior to the masking noise upper limit frequency was reported to be slightly reduced and therefore hearing paradoxically enhanced [Sandor et al., Aviat. Space Environ. Med. 75, 9525 (2004)]. It was analyzed as an indirect evidence of attenuation of low-frequency perception in relation with the shape of the masking noise and the alteration of associated upwards spread of masking effect. A pressure modification in cochlea was supposed to occur under +Gz, due to transmission of intracranial pressure through the cochlear duct, as observed in a clinical case [Portier et al., Ann. Otol. Rhinol. Laryngol. 111, 817–820 (2002)]. We developed a finite element model of cochlear mechanics revealing a shape modification of the apical side of cochlea under the pressure modification compatible with +4-Gz acceleration. Manoussaki and colleagues [Phys. Rev. Lett. 96(8), 088701 (2006)] emphasize the role of cochlea curvature in low frequency perception. Our experimental and computational results reinforce this role of cochlea curvature in low frequency perception.
Off-frequency listening in a pitch matching experiment
Authors: Eckstein Veronica , Berg Bruce G.
Published: October 2013

A pitch-matching paradigm was used to investigate the pitch of three-tone complexes. For different conditions, the central tone was 200, 1000, or 2000 Hz with the side tones spaced by either 30 or 45 Hz. The tones were of equal intensity or a signal was added in phase to the central tone with a level of 5, 0, or 5 dB relative to the side tones. Listeners adjusted the frequency of a pure tone to match the pitch of the complex. According to a model known as the envelope weighted average of the instantaneous frequency (EWAIF) [L. Feth, Percept. Psychopys. 15, 375–378 (1974)], the pitch should be approximately equal to the center frequency for all conditions. Contrary to this prediction, increasing the bandwidth or decreasing the signal level systematically lowered the pitch. However, the results are consistent with EWAIF calculations if the stimuli are first passed through the skirt of an auditory filter. This method may provide an alternative technique for estimating the filtering properties of the auditory system. [Work supported by Center for Hearing Research, UCI.]
Sample discrimination of frequency differences with ipsilateral and contralateral distracters
Authors: Neff Donna L. , Jesteadt Walt , Leibold Lori J.
Published: October 2013

This experiment examined the effect of ipsilateral and contralateral tonal distracters on sample discrimination of frequency differences. In the 2AFC baseline task, four listeners indicated which of two intervals, each containing a two-tone target complex, was higher in pitch. The pairs of target tones were drawn from Gaussian frequency distributions centered at low-, middle-, and high-frequency regions. Two distracter tones were then added, one from each of the two nontarget frequency regions (e.g., low targets, middle and high distracters). Distracter tones were either randomly drawn from a Gaussian frequency distribution or fixed in frequency at the mean of the distribution. Across conditions, targets were in the left or right ears, with distracters in the ipsilateral or contralateral ear. There was little effect of target ear or effect of adding fixed-frequency distracters in either ear. Effects of random-frequency distracters varied across subjects and frequency regions, with both ipsilateral and contralateral distracters showing large effects for some subjects and conditions. Distracters were least effective with middle-frequency targets. The ability to use the ear as a channel appears to depend on both the relative variability and relative frequency regions of the targets compared to the distracters. [Work supported by NIDCD.]
The role of fundamental frequency and target segregation in the presence of same-band and different-band maskers
Authors: Iyer Nandini , Brungart Douglas , Simpson Brian
Published: October 2013

A number of recent studies on multitalker speech perception have been based on envelope-modulated, sine-wave-excited speech similar to the kind used to simulate the processing used in cochlear implants. Although these modulated sine-band signals are highly intelligible in isolation, they are typically much harder to segregate in multitalker listening tasks than normal speech. In this experiment, we examined the extent to which the difficulty in segregating these signals could be attributed to the absence of the fundamental frequency F0 that is present in natural speech. Psychometric functions were measured with speech and noise maskers for three types of signals: (1) natural speech; (2) sine-excited cochlear implant speech (CIS); and (3) F0-excited CIS, which was generated in the same way as the CIS but with a simulated glottal pulse train as an excitation source. The results show that performance was better with the F0-excited CIS than with the sine-excited CIS in all conditions, including those where the target and masking talkers overlapped in frequency. Performance was also generally better when the F0-excited CIS was generated with F0 values from different-sex rather than same-sex talkers. The results confirm the importance of F0 cues in the segregation of competing speech signals.
Change deafness and how the auditory system organizes sounds
Authors: Gregg Melissa K. , Samuel Arthur G.
Published: October 2013

Change blindness, or the failure to detect changes to a visual scene that seem blatantly obvious after the fact, has been demonstrated in a variety of different situations. Exploration of auditory failures to detect change has been far less studied, even though demonstrations of change deafness could have important theoretical implications. Four experiments were conducted to explore the processes involved in change deafness by measuring explicit change detection as well as auditory object encoding of natural auditory scenes. Considerable change deafness occurred, even though auditory objects were encoded quite well. Change detection performance was better when stimuli were not presented at distinct spatial locations (experiment 1) than when they were presented with spatial cues (experiment 2). Familiarity with the objects did not affect detection or recognition performance. In order to establish an effective cue for auditory detection and recognition, performance was assessed when auditory stimuli were presented in distinct regions of perceptual space based on fundamental frequency and harmonicity (experiments 3 and 4). Implications for the mechanisms responsible for change deafness and auditory sound organization are discussed.
The application of the equal energy hypothesis (EEH) to interrupted, intermittent, and time-varying non-Gaussian noise exposures
Authors: Hamernik Roger P. , Qiu Wei , Davis Robert I.
Published: October 2013

Industrial data and animal research show that non-Gaussian (nonG) noise exposures are more hazardous to hearing than energy equivalent Gaussian (G) exposures. A statistical metric, kurtosis [b(t)], was shown to order the severity of noise-induced trauma following a nonG exposure relative to an energy and spectrally equivalent G exposure. Four groups of chinchillas were exposed to one of four different nonG interrupted, intermittent, and time-varying (IITV) noise paradigms over 19 days at an Leq=103 dB(A) SPL, with b(t)=25 or 50. Each daily exposure consisted of two 4.25-h periods with an hour break. Each 4.25-h exposure was interrupted for 15 min and each 5-day sequence was separated by a 2-day break. Each daily IITV exposure followed one of two different SPL temporal patterns that varied between 90 and 108 dB(A). All IITV exposures produced a toughening effect that did not alter the degree of noise-induced trauma. NonG noise produced as much trauma as a G exposure at 110 dB. Despite very different temporal paterrns for the b(t)=50 exposures, trauma was the same. Thus within a common class [i.e., the same Leq and b(t)] of nonG, IITV exposure, the EEH may apply. [Work supported by NIOSH.]
The application of statistical learning models to the prediction of noise-induced hearing loss
Authors: Qiu Wei , Ye Jun , Hamernik Roger P.
Published: October 2013

Three powerful nonlinear statistical algorithms [a support vector machine (SVM), radial basis function network (RBFN), and regression tree] were used to build prediction models for noise-induced hearing loss (NIHL). The models were developed from an animal (chinchilla) database consisting of 322 animals exposed to 30 Gaussian and non-Gaussian noise conditions. The inputs for the models were either energy or energy plus kurtosis. The models predict inner hair cell (IHC) loss, outer hair cell (OHC) loss, and postexposure threshold shift (PTS) at 0.5, 1, 2, 4, and 8 kHz. The models incorporating both energy and kurtosis improved the prediction performance significantly. The average performance improvement for the prediction of IHC loss was as much as 55%, for OHC loss it was 66% and for PTS, 61%. The prediction accuracy of SVM and RBFN with energy plus kurtosis for all three outputs (predictions) was more than 90% while for the regression tree model it was more than 85%. Energy is not a sufficient metric to predict hearing trauma from complex (non-Gaussian) noise exposure. A kurtosis metric may be necessary for the prediction of NIHL. [Research supported by NIOSH.]
Noise-induced hearing loss from non-Gaussian equal energy exposures
Authors: Davis Robert I. , Qiu Wei , Hamernik Roger P.
Published: October 2013

Data from several different exposures [Hamernik et al., J. Acoust. Soc. Am. 114, 386–395 (2003)] showed that, for equivalent energy [Leq=100 dB(A)] and spectra, exposure to a continuous, non-Gaussian (nonG) noise produces greater hearing and sensory cell loss in the chinchilla than a Gaussian (G) noise. The statistical metric, kurtosis, could order the extent of the trauma. We extend these results to Leq=90 and 110 dB(A), non-Gaussian noises generated using broadband noise bursts, and band-limited impacts within a continuous G background noise. Data from nine new experimental groups with 11 or 12 chinchillas/group will be presented. Evoked response audiometry established hearing thresholds and surface preparation histology quantified sensory cell loss. There were clear intensity-related effects. At the lowest levels there were no differences in the trauma produced by G and nonG exposures. At Leq=90 dB(A), nonG exposures produced increased trauma relative to equivalent G exposures. By removing energy from the impulsive transients by limiting their bandwidth, trauma could be reduced. The use of noise bursts to produce the nonG noise also reduced the amount of trauma. A metric based on kurtosis and energy may be useful in modifying existing exposure criteria. [Work supported by NIOSH.]
Temporal characteristics of extraction of size information in speech sounds
Authors: Takeshima Chihiro , Tsuzaki Minoru , Irino Toshio
Published: October 2013

We can identify vowels pronounced by speakers with any size vocal tract. Together, we can discriminate the different sizes of vocal tracts. To simulate these abilities, a computational model has been proposed in which size information is extracted and separated from the shape information. It is important to investigate temporal characteristics of the size extraction process. Experiments were performed for listeners to detect the size modulation in vowel sequences. All the sequences had six segments. Each segment contained one of three Japanese vowels: ‘‘a,’’ ‘‘i,’’ and ‘‘u.’’ Size modulation was applied by dilating or compressing the frequency axis of continuous, STRAIGHT spectra. Modulation was achieved by changing the dilation/compression factor in sinusoidal functions. The original F0 pattern of the base sequence, except for warping of the time axis, was used for all stimuli. The minimum modulation depth at which listeners were able to detect the existence of modulation was measured as a function of the modulation frequency. The results will be compared with low-pass characteristics in a temporal modulation transfer function obtained with the amplitude-modulated noise. They will be discussed in relation to a computational model based on the Mellin transformation.
She hears seashells: Detection of small resonant cavities via ambient sound
Authors: Chamberlain Ethan J. , Rosenblum Lawrence D. , Robart Ryan L.
Published: October 2013

There is evidence that blind listeners can detect the presence of obstacles based on how the obstacles structure the ambient sound in a quiet room [Ashmead et al., J. Vis. Impair. Blindn. 9, 615 (1998)]. Potentially, this ability is based on auditory sensitivity to the buildup of ambient wave interference patterns in front of the obstacle. This effect is not unlike how the internal structure of a seashell amplifies a room’s ambient sound to emulate the sound of the ocean. Experiments were conducted to determine whether unpracticed, sighted listeners were sensitive to this information. Blindfolded listeners were placed in a quiet room and were asked to determine the location of a small resonant cavity placed next to either their left or right ear. Results revealed that listeners were very accurate at this task. Follow-up experiments examined the limits of this sensitivity as well as its acoustical support. These findings suggest that unpracticed listeners might be sensitive to subtle changes in the ambient acoustic structure of a quiet environment.
Comparing vowel formant thresholds from two tasks: Classification versus 2-alternative forced choice (2AFC) adaptive tracking
Authors: Oglesbee Eric , Kewley-Port Diane
Published: October 2013

Accurate classification of vowels in American English is difficult because of the number of acoustically similar vowels. Previous experiments in our lab [Kewley-Port et al., J. Acoust. Soc. Am. 118, 1929–1930 (2005)] described a new method to obtain formant thresholds using a classification task rather than the more typical 2AFC task. The goal of the present experiment was to directly compare formant thresholds estimated from a classification task with a modified 2AFC paradigm using adaptive tracking. Stimuli, generated by STRAIGHT, consisted of separate continua for formants F1 and F2 based on natural productions of ‘‘bid’’ shifted to ‘‘bed,’’ and ‘‘cut’’ shifted to ‘‘cot.’’ Separate 7- and 14-step continua were created for the classification and 2AFC tasks, respectively. Eight subjects participated first in the classification task, followed by the 2AFC task. Classification threshold results here replicated those observed in our previous experiments. Within-subject comparisons of the classification and 2AFC data refined our method for calculating a classification threshold from logistic psychometric functions. Individual thresholds calculated using this refined method were very similar to those from the 2AFC task. Results demonstrate the viability of using a more natural, single-interval classification task to estimate formant discrimination thresholds. [Work supported by Grant NIHDCD-02229.]
Cochlear and cognitive models for speech enhancement
Authors: Dominguez Melissa , Bondy Jeff , Dittberner Andrew
Published: October 2013

There has been a long running interest in using cochlear models for audio processing. Psychophysical masking stemming from normal cochlear operation is used as the basis for most audio compression circuits, while the cochleas mel-frequency response is mimicked by most automatic speech recognition circuits. An area that has been less well explored in audio processing is the auditory brain. Recent research shows that cognitive abilities are a good predictor of peformance on many hearing tasks, especially those which are more complex and realistic. By extending a nonlinear, adaptive cochlear model with cognitive modules a novel tool for sound assessment is made that allows an estimate of cognitive load. Quantitative offline benefit has never been modeled before. We test the new predictor on noise reduction circuits in hearing aids. This family of algorithms is well known to not increase intelligibility but has been shown to reduce perceived noisiness. This reduction is proposed as equivalent to reducing cognitive load. The elderly, with their heavier reliance on high level processing, could greatly benefit from the reduction in cognitive load. A new algorithm for reducing cognitive load is compared to spectral subtraction algorithms.
Cross-modal plasticity and the sensitive period for cochlear implantation
Authors: Buckley Kristi A. , Tobey Emily A. , Sharma Anu
Published: October 2013

Previous research suggests prelingually deaf individuals who receive a cochlear implant early in childhood develop better oral communication skills than those who receive their implant later. However, the mechanisms influencing this sensitive period are not well understood. This investigation explores one possible mechanism limiting the sensitive period for cochlear implantation, cross-modal plasticity. Cross-modal plasticity occurs when one sensory system recruits cortical processing resources of another absent or damaged sensory system. This reallocation of cortical processing resources may influence the ability of the auditory system to respond to restored auditory sensation through the electrical stimulation of a cochlear implant. In order to investigate the possible relationship between cross-modal plasticity and the sensitive period for cochlear implantation, we examined the visual evoked potential (VEP) to peripheral motion in prelingually deaf children and adults, and normal-hearing children and adults. The VEP response source is compared across ages and groups. Preliminary data from adults indicate the source of the VEP response in deaf individuals originates from the temporal lobe, compared to the parietal lobe in normal hearing individuals, suggesting evidence of cortical reorganization in deafness. [Work funded by NIH F31DC007007 (K. Buckley, P.I.), R01DC04558 (E. Tobey, P.I.), and R01DC006257 (A. Sharma P.I.).]
Pitch discrimination in children using cochlear implants
Authors: McKinnon Amy , Kiefte Michael
Published: October 2013

Research in pitch perception by cochlear implant users has focused primarily on postlingually deafened adults. Little is currently known regarding the pitch perception abilities of those who are implanted at a very early age, yet many children receive cochlear implants when they are less than 2 years old. Given the effects of brain plasticity, it is conceivable that pitch perception by early cochlear implant users may be much better than that of their older counterparts. This study examines pitch discrimination thresholds in young cochlear-implant users between the ages of 4 and 16. A computer game was developed to determine difference limens for fundamental frequency in vowellike stimuli at three referent frequencies: 100, 200, and 400 Hz. Two different tasks were employed: pitchdiscrimination, in which subjects were asked whether two stimuli are same or different, and pitch ranking, in which participants determine which of two stimuli is higher in pitch. Normal-hearing matches were tested to control for maturational effects, and adult cochlear implant users were also tested to compare findings with other studies. [Work supported by the Nova Scotia Health Research Foundation.]
Implementing a psychophysical interface for the sound processor for electrical and acoustic research version 3 (SPEAR3)
Authors: Stohl Joshua S. , Throckmorton Chandra S. , Collins Leslie
Published: October 2013

Current speech processing strategies use amplitude-modulated fixed rate pulse trains to communicate information. Using acoustic models, researchers have recently demonstrated that variable stimulation rate strate- gies may provide an improvement of speech perception in noise and music perception [Nie et al., 2005; Stohl and Collins, 2006; Throckmorton et al. (2006) (in press)]. It has been hypothesized that successful implementation of these strategies will require psychophysics-based tuning. An experimental interface is needed to implement such psychophysical experiments, and most interfaces provided by implant manufacturers do not provide the stimulus design flexibility necessary. HearWorks provides the SPEAR3 developmental sound processor, which is capable of dynamically updating the stimulation rate and offers bimodal and bilateral configurations. Assembly and Visual Basic code is included with the SPEAR3, but must be modified and expanded to implement dynamic stimulus presentation and graphical user interfaces for specific psychophysical tasks. Using data collected from Nucleus CI 24 implant users, we will demonstrate that the SPEAR3 may be used to implement general psychophysical experiments. The ability of the SPEAR3 speech processor to implement variable stimulation rates is critical to future psychophysical testing of variable stimulation rate processing strategies.
Phased array steering of structure-borne sound radiated from a flexible beam by active modal control
Authors: Tan Alfred , Halim Dunant , Tanaka Nobuo
Published: October 2013

This paper analytically demonstrates the implementation of a control strategy to actively steer the structure-borne sound radiated from a simply supported beam structure, which is excited by an arbitrary mono-frequency force. The surface of the beam is discretized into many finite elemental sound radiators that correspond to their respective nodal points. The dynamics of the beam structure are identified in order to modify the modal vibration characteristic for beamsteering purpose. The acoustic power is formulated in terms of its velocity according to the Rayleigh expression. The key to the control strategy is to combine the a priori knowledge of the structural modal characteristic with the sensors measurements. As a result, this is used to control the normal surface vibration velocity profile of the beam structure into a set of congruent elemental sound radiators, each differing only by successive delayed phase in order to steer the radiated sound beam pattern into a desired far field direction. The arrangement of the sensors/actuators on the beam structure is designed to instill such a unique set of elemental sound radiators. Numerical studies are performed to evaluate the effectiveness of the proposed sound steering concept into the far-field hemisphere. [Work supported by JSPS.]
Acoustic backscattering from fluid-filled submerged prolate spheroidal shells
Authors: Boisvert Jeffrey E. , Hayek Sabih I.
Published: October 2013

The equations of motion for nonaxisymmetric vibration of prolate spheroidal shells of constant thickness were derived using Hamilton’s principle [S. I. Hayek and J. E. Boisvert, J. Acoust. Soc. Am. 114, 2799–2811 (2003)]. The shell theory used in this derivation includes shear deformations and rotatory inertias. The shell displacements and rotations were expanded in infinite series of comparison functions. These include associated Legendre functions in terms of the prolate spheroidal angular coordinate and circular functions in the azimuthal angle coordinate. The fluid-filled shell is insonified by a plane wave with an arbitrary angle of incidence. The external and internal fluid loading impedances were computed using an eigenfunction expansion of prolate spheroidal wavefunctions. Far-field backscattered acoustic pressure spectra are presented as a function of the angle of incidence for several shell thickness-to-half-length ratios ranging from 0.005 to 0.1, and for various shape parameters, a, ranging from an elongated spheroidal shell (a=1.01) to a spherical shell (a∼100). A comparison of the backscattering from fluid-filled and empty shells is presented at selected plane wave incident angles. [Work supported by the ONR/ASEE Summer Faculty Research Program and the NAVSEA Newport ILIR Program.]
Vibration absorption by an undamped beam element
Authors: Koc Ilker Murat , Akay Adnan , Carcaterra Antonio
Published: October 2013

Through two complementary approaches, using modal response and wave propagation, this presentation will show the conditions under which a decaying impulse response, or a nearly irreversible energy trapping, takes place in a linear conservative continuous system. The results show that the basic foundation of near-irreversibility or pseudo-damping rests upon the presence of singularity points in the modal density of the systems. To illustrate the concept of pseudo-damping in detail, a simple undamped beam is modified to introduce a singularity point in its modal density distribution. Simulations show that by a suitable application of a compressive axial force to an undamped beam on an elastic foundation, the impulse response of a beam shows the characteristics of a nearly irreversible energy trap and a decaying impulse response. Attaching such a modified beam to a single degree of freedom oscillator shows energy trapping by the beam producing pseudo damping. [Research carried out while AA served at NSF.]
Pseudo-damping in undamped plates and shells
Authors: Carcaterra Antonio , Akay Adnan
Published: October 2013

Pseudo-damping is a counter-intuitive phenomenon observed in a special class of linear structures that exhibit an impulse response characterized by a decaying amplitude, even in the absence of any dissipation mechanism. The conserved energy remains within but designated parts of the system. Pseudo-damping develops when the natural frequency distribution of the system includes condensation points. The recently formulated theoretical foundation of this phenomenon, based on mathematical properties of special trigonometric series, makes it possible to describe a class of mechanical systems capable of displaying pseudo-damping characteristics. They include systems with discrete oscillators and one-dimensional continuous beamlike structures already reported by the authors in recent studies. This paper examines development of pseudo-damping phenomenon in two-dimensional structures, using plates and shells as examples, and shows how a preloaded plate on an elastic foundation can lead to pseudo-damping. Moreover, in the case of curved shell elements examined here, pseudo-damping can result due to the curvature of the structure, which naturally introduces condensation points in the modal density. [Research carried out while AA served at NSF.]
Fundamentals of apparent damping phenomena in linear conservative systems
Authors: Carcaterra Antonio , Akay Adnan
Published: October 2013

This presentation addresses a class of irreversible phenomena that can develop in linear conservative systems and provides a theoretical foundation to explain the underlying principles. Recent studies have shown that energy can be introduced to a linear system with near irreversibility, or energy within a system can migrate to a subsystem nearly irreversibly, even in the absence of dissipation. Inspired by the properties of probability distribution functions, the general formulation developed here is based on particular properties of harmonic series, which form the common basis of linear dynamic system models. The results demonstrate the existence of a special class of linear nondissipative dynamic systems that exhibit nearly irreversible energy exchange and possess a decaying impulse response. The formulation and its results also support the recent studies that observed near irreversibility and apparent damping in several dynamic systems and provide a common theoretical foundation for such behavior. [Research carried out while AA served at NSF.]
Using an enhanced constrained layer damping model to assess relative damping contributions
Authors: Xie Zhengchao , Shepard W. Steve
Published: October 2013

Constrained layer damping (CLD) is an effective passive vibration control approach in which damping comes from the core layer’s deformation. In the most general sense, this deformation will include shear, longitudinal extension, and transverse compression deformations. In this work, new analytical models and their single-layer finite-element (FE) implementations are used to examine the dependence of these types of damping on the frequency and the core layer’s thickness for different boundary conditions. This information can be important in cases where a simplified model is needed with an acceptable error. The sandwich beam’s response is examined by using various tools in order to determine the important aspects of the model, with particular emphasis on the relative importance of each of the three types of damping. Then, frequency responses found using different single-layer finite elements are compared for different boundary conditions. By using both the analytical models and FE method results, guidance is provided on how to choose an appropriately simplified model or finite element for more practical analyses.
When is a phonological rule acquired? A look at children’s production on syllable-final nasals in Taiwan Mandarin
Authors: Hung Renee , Fon Janice
Published: October 2013

Syllable-final nasals, /n/ and /N/, tend to be merged when they are after /i/ and ■ in Taiwan Mandarin, but in different directions. For /i/, /n/ is merged with /N/, while for ■, /N/ is merged with /n/ (Chen, 1991; Tse, 1992; Hsu, 2005). This study thus aims to examine whether children in Taiwan merge syllable-final nasals in Mandarin the way adults do. Fifty Grade-2 and Grade-6 students would read monosyllabic words, containing 3 [vowels (/i/, ■, /a/)] ×4 (tones) =12 minimal pairs differing only in nasal endings. They would repeat the words twice, once in Zhuyinfuhao, a local phonetic system, and once in traditional Chinese characters. Preliminary results indicated that Grade-2 children treated the /eN/ words very similarly to adults, although the occurrences of nasal merge were less frequent in the Zhuyinfuhao set than in the character set. For vowel /i/, however, merging of both directions could be found in both Mandarin characters and Zhuyinfuhao.
Phonetic development of word-initial Korean stops in young Korean children
Authors: Kim Minjung , Stoel-Gammon Carol
Published: October 2013

A number of studies have investigated developmental patterns of stops in various languages through the instrumental analysis; however, very little is known about phonetic characteristics of Korean stops in speech of young Korean children. In Korean, stops are produced at three places of articulation (labial, alveolar, velar); at each place, there is a three-way contrast, yielding nine stops in word-initial position. All stops are voiceless and are differentiated by several acoustic parameters including VOT, f0 of the following vowel, and the amplitude difference of the first and second harmonics (H1−H2) at the voice onset of the following vowel. The present study examines developmental aspects of word-initial Korean stops by measuring values of VOT, f0, and H1−H2 at the onset of the following vowel in words produced by Korean children aged 30, 36, 42, and 48 months. Findings will focus on the phonetic features used by Korean children to contrast the three-way stops and on comparisons between the phonetic patterns of stops produced by Korean children and Korean adults.
Patterns of anticipatory lingual coarticulation in typically developing children
Authors: Nissen Shawn , Boucher Kurtt , Parson Mathew
Published: October 2013

Many studies have examined the patterns of speech coarticulation in adults and younger speakers; however previous findings have not established a consistent developmental perspective. There are contrasting views on whether children at early stages of development demonstrate more, less, or about the same amount of anticipatory coarticulation than adults. This study will focus on describing the patterns of anticipatory lingual coarticulation in the obstruent productions of three groups of children between 3 and 6 years of age (N=42) and one comparison group of adults (N=14). Frequency measures for the first and second formants were extracted from multiple tokens of a centralized and unstressed vowel (schwa) spoken prior to two different sets of productions. The first set of productions consisted of the target vowel followed by a series of real words containing an initial CV(C) syllable, while the second set consisted of nonword productions with a relatively constrained phonetic context. Formant values were transformed to a perceptually normalized scale (ERB) prior to statistical analysis. Analysis of variance was utilized to determine if the formant frequencies varied systematically as a function of age, gender, and phonetic context. [Work supported by research funding from Brigham Young University.]
Developmental vowel acquisition data obtained by a band-filtering analysis method: Results from Hungarian children
Authors: Zajdó Krisztina
Published: October 2013

A recently developed band-filtering analysis method (van der Stelt et al., 2003, 2005; Zajdó et al., 2004) that minimizes the dependence of the results on fundamental frequency allows for a dependable identification of spectral measures in children’s vowels. In the scripts, selection of segments with certain acoustic features (e.g., sound quality, F0) is followed by the calculation of spectral envelopes between 0–7 kHz, resulting in 40 filter values per spectrum. An intensity matrix is produced with data from each 40 filters. Data reduction is achieved through prinicipal component analysis. Results indicate that the first two principal components are related to the F1 and F2 of vowels, both in adults (Pols, 1977) and children (Zajdó et al., 2005). Analyses of unlabeled vowel productions in Hungarian-speaking children at 2; 0, 3; 0 and 4; 0 years show that the first two eigenvectors account for >50% of the variability in all age groups. By using these eigenvectors, age-specific reference planes are created. Mapping phonemically labeled vowel measures onto the 4; 0-year-old’s plane from each age group suggests that children produce decreasingly overlapping vowel categories as they age. With development, vowel categories are increasingly specified, covering more distinct areas of the acoustic vowel space. [Work supported by UW.]
Infants listening to songs: Exploring a processing trade-off between phonetic and pitch patterns
Authors: Cardillo Gina C. , Kuhl Patricia K.
Published: October 2013

This investigation explored 11-month-olds’ responses to changes in the phonetic (lyric) and pitch (melody) content of songs. Sixty infants were tested using a between-subjects auditory preference paradigm. After being familiarized with a four-note song, infants were presented with both the familiar song and a new song that contained either a novel syllable or pitch order. In experiment 1, infants preferred listening to a novel melody when the phonetic content was redundant, but showed no preference when the identical melody change occurred in the presence of variegated phonetic content. In experiment 2, we tested the hypothesis that infants presented with songs containing variegated phonetic information would attend to changes in words but not melodies. Infants marginally preferred listening to novel songs when only the lyrics changed, but did not show a preference when only the melodies changed. Taken together, the results are consistent with a priori predictions, and suggest that even though infants can recognize melodic changes when they are presented in isolation, identical changes become more difficult to detect when more complex phonetic information is introduced. Thus, neural resources at this age may be more heavily committed to processing phonetic information than pitch information when both are present. [Work supported by the J.S.McDonnell Foundation, NIH.]
The bilingual brain: A comparison of native and non-native speech perception in monolingual and bilingual infants
Authors: Kuhl Patricia K. , Coffey-Corina Sharon , Padden Denise , Rivera-Gaxiola Maritza
Published: October 2013

Infants raised in monolingual families are equally good at native and non-native speech discrimination early in life. By 12 months, performance on native speech has significantly improved while non-native performance declines. We tested bilingual American infants at 7 and 11 months of age on native (/ta-pa/) and non-native (Mandarin affricate-fricative) contrasts used in the monolingual tests. Phonetic discrimination was assessed using behavioral (conditioned head-turn) and brain (event-related potential) measures. The MacArthur Communicative Development Inventory estimated infants developing language skills at 14, 18, 24, and 30 months of age. The monolingual data [Kuhl et al., Language Learning and Development (2005)] demonstrated that at 7 months of age, infants native and non-native speech perception skills predicted their later language development, but differentially. Better native phonetic perception predicted more rapid language development between 14 and 30 months, whereas better non-native phonetic perception predicted slower language development over the same time period. Performance of bilingual infants on the same speech perception tasks, and their patterns of language growth between 14 and 30 months, will be compared to those of the monolingual infants, and a model that accounts for the results will be described. [Work supported by NSF, NIH, and the Human Frontiers Science Program.]