bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed Dispersal by Kerama Deer (Cervus nippon keramae) on Aka Island, the Ryukyu Archipelago, Japan1
Authors: Yamashiro Asuka , Yamashiro Tadashi
Published: March 2006

Endozoochorous seed dispersal by kerama deer (Cervus nippon keramae) was investigated at four sites on Aka Island, the Ryukyu Archipelago, Japan. Kerama deer feces contained seeds of 35 plant species. Most of the germinated seeds were small (1.3 ± 0.18 mm) and had a hard coat, comparable to the germinated seeds in several other studies of endozoochorous seed dispersal by herbivores. Both the numbers and species compositions of seeds differed among the four sites, reflecting differences in the food available to kerama deer among habitats. Although many graminoid seeds were found in the two open habitats (Sites A and B) and in the adjoining forest habitat (Site C), woody plant seeds dispersed endozoochorously by birds and mammals were dominant in the forest (Site D), away from the marsh. Although a majority of the graminoid species was growing in open habitats such as the marsh and open fields, few were growing in the forest. Therefore, the kerama deer spread many open‐habitat graminoid seeds to the open and forest habitats. If a high density of kerama deer persists for a long time and gaps in forests are created by browsing kerama deer or by other means, graminoid species may spread substantially on Aka Island. Therefore, it is possible that seed dispersal by forest deer contributes to the expansion of grasslands.
How does environmental variation influence body mass, body size, and body condition? Roe deer as a case study
Authors: Toïgo Carole , Gaillard Jean‐Michel , Van Laere Guy , Hewison Mark , Morellet Nicolas
Published: March 2006

We tested the influence of population density and of drought intensity (measured as the Gaussen Index in spring and summer of the year of birth) on winter body mass, hind foot length, and body condition of roe deer fawns. Body mass decreased with increasing density and increased with increasing Gaussen Index in summer, in a similar way for both males and females. Hind foot length of males showed the same response. On the other hand, hind foot length of females decreased with increasing density only after dry summers, hence when environmental conditions were very harsh. Body condition was affected neither by density nor by drought intensity. Our results indicate that body mass and size are much better indicators of phenotypic quality than body condition in roe deer. The sex‐specific responses of body size to environmental conditions could correspond to a differential allocation in favour of daughters by heavier than average roe deer mothers.
Novel methods improve prediction of species’ distributions from occurrence data
Authors: Elith* Jane , H. Graham* Catherine , P. Anderson Robert , Dudík Miroslav , Ferrier Simon , Guisan Antoine , J. Hijmans Robert , Huettmann Falk , R. Leathwick John , Lehmann Anthony , Li Jin , G. Lohmann Lucia , A. Loiselle Bette , Manion Glenn , Moritz Craig , Nakamura Miguel , Nakazawa Yoshinori , McC. M. Overton Jacob , Townsend Peterson A. , J. Phillips Steven , Richardson Karen , Scachetti‐Pereira Ricardo , E. Schapire Robert , Soberón Jorge , Williams Stephen , S. Wisz Mary , E. Zimmermann Niklaus
Published: March 2006

Prediction of species’ distributions is central to diverse applications in ecology, evolution and conservation science. There is increasing electronic access to vast sets of occurrence records in museums and herbaria, yet little effective guidance on how best to use this information in the context of numerous approaches for modelling distributions. To meet this need, we compared 16 modelling methods over 226 species from 6 regions of the world, creating the most comprehensive set of model comparisons to date. We used presence‐only data to fit models, and independent presence‐absence data to evaluate the predictions. Along with well‐established modelling methods such as generalised additive models and GARP and BIOCLIM, we explored methods that either have been developed recently or have rarely been applied to modelling species’ distributions. These include machine‐learning methods and community models, both of which have features that may make them particularly well suited to noisy or sparse information, as is typical of species’ occurrence data. Presence‐only data were effective for modelling species’ distributions for many species and regions. The novel methods consistently outperformed more established methods. The results of our analysis are promising for the use of data from museums and herbaria, especially as methods suited to the noise inherent in such data improve.
Migrants in tropical bird communities: the balanced breeding limitation hypothesis
Authors: Johnson Matthew D. , Strong Allan M. , Sherry Thomas W.
Published: March 2006

Explanations for the ecological integration of migratory and non‐migratory (resident) insectivorous birds in the tropics have been complicated by the paradox that arthropod abundances are low when bird abundances reach their annual peak. The breeding currency hypothesis and the nest predation hypothesis both account for this paradox by postulating that residents are held below the non‐breeding season carrying capacity, which frees resources available for migratory insectivores. The breeding currency hypothesis suggests residents are limited by food suitable for nestlings, whereas the nest predation hypothesis emphasizes the primacy of high rates of nest predation. However, theoretical arguments suggest that food availability and predation risk interact strongly to limit breeding birds. We use graphical analyses to extend the breeding currency hypothesis to incorporate effects of nest predation. This yields a more synthetic and realistic model for the integration of migrant and resident insectivores in the tropics – the balanced breeding limitation hypothesis.
Active vibration control using an inertial actuator with internal damping
Authors: Paulitsch Christoph , Gardonio Paolo , Elliott Stephen J.
Published: March 2006

Collocated direct velocity feedback with ideal point force actuators mounted on structures is unconditionally stable and generates active damping. When inertial actuators are used to generate the control force, the system can become unstable even for moderate velocity feedback gains due to an additional −180° phase lag introduced by the fundamental axial resonant mode of the inertial actuator. In this study a relative velocity sensor is used to implement an inner velocity feedback loop that generates internal damping in a lightweight, electrodynamic, inertial actuator. Simulation results for a model problem with the actuator mounted on a clamped plate show that, when internal relative velocity feedback is used in addition to a conventional external velocity feedback loop, there is an optimum combination of internal and external velocity feedback gains, which, for a given gain margin, maximizes vibration reduction. These predictions are validated in experiments with a specially built lightweight inertial actuator.
Effects of the inclination of a rigid wall on the free vibration characteristics of acoustic modes in a trapezoidal cavity
Authors: Sum K. S. , Pan J.
Published: March 2006

The coupling between rigid-walled modes of a rectangular cavity (RC modes) is used to obtain the shapes and resonance frequencies of rigid-walled modes of a trapezoidal cavity (TC modes) with an inclined rigid wall. A method is established to identify the TC modes, where the modes can be defined to evolve from individual RC modes. The wall inclination generates two coupling mechanisms, namely, the local coupling where the RC modes couple at the inclined wall, and the global coupling where the RC modes couple throughout the trapezoidal volume. The latter arises from the nonorthogonality of the RC modes in the trapezoidal volume. Both couplings are selective that only RC modes with the same number of nodes in the direction perpendicular to the inclination are coupled to each other. For small inclinations, each TC mode possesses the distorted shape of the RC mode that evolves it. When the inclination is increased, the TC-mode shape becomes complicated and unrecognizable, and extrema can also exist in the resonance frequency of the TC mode. These behaviors are determined by the behaviors of the local and global couplings of the RC mode. This paper provides an understanding of how the free vibration characteristics of TC modes change with the inclination and what determines these changes.
A geometric representation of spectral and temporal vowel features: Quantification of vowel overlap in three linguistic varieties
Authors: Wassink Alicia Beckford
Published: March 2006

A geometrical method for computing overlap between vowel distributions, the spectral overlap assessment metric (SOAM), is applied to an investigation of spectral (F1, F2) and temporal (duration) relations in three different types of systems: one claimed to exhibit primary quality (American English), one primary quantity (Jamaican Creole), and one about which no claims have been made (Jamaican English). Shapes, orientations, and proximities of pairs of vowel distributions involved in phonological oppositions are modeled using best-fit ellipses (in F1×F2 space) and ellipsoids (F1×F2×duration). Overlap fractions computed for each pair suggest that spectral and temporal features interact differently in the three varieties and oppositions. Under a two-dimensional analysis, two of three American English oppositions show no overlap; the third shows partial overlap. All Jamaican Creole oppositions exhibit complete overlap when F1 and F2 alone are modeled, but no or partial overlap with incorporation of a factor for duration. Jamaican English three-dimensional overlap fractions resemble two-dimensional results for American English. A multidimensional analysis tool such as SOAM appears to provide a more objective basis for simultaneously investigating spectral and temporal relations within vowel systems. Normalization methods and the SOAM method are described in an extended appendix.
Noise annoyance and activity disturbance before and after the erection of a roadside noise barrier
Authors: Nilsson Mats E. , Berglund Birgitta
Published: March 2006

Questionnaire studies were conducted in a residential area before and after the erection of a 2.25m high noise barrier of conventional type along a heavily traveled road (19600vehicles∕24h). The interval between studies was two years. Houses closest to the barrier received a sound-level reduction from ∼70.0to62.5dB Lden at the most exposed facade. The sound-level reduction decreased with distance to the road, and was negligible for houses at more than 100m distance. Up to this distance, the noise barrier reduced residents’ noise annoyance outdoors and indoors as well as improved speech communication outdoors. Indoors, speech communication and sleep disturbance were slightly but nonsignificantly improved. Predictions of the number of annoyed persons from published exposure-response curves (in Lden) agreed with the percentage of residents being annoyed when indoors, before and after the barrier. Conversely, the percentage of residents being annoyed when outdoors clearly exceeded the predictions. These results suggest that these exposure-response curves may be used in predicting indoor situations, but they should not be applied in situations where outdoor annoyance is at focus.
Multiple ping sonar accuracy improvement using robust motion estimation and ping fusion
Authors: Yu Lian , Neretti Nicola , Intrator Nathan
Published: March 2006

Noise degrades the accuracy of sonar systems. We demonstrate a practical method for increasing the effective signal-to-noise ratio (SNR) by fusing time delay information from a burst of multiple sonar pings. This approach can be useful when there is no relative motion between the sonar and the target during the burst of sonar pinging. Otherwise, the relative motion degrades the fusion and therefore, has to be addressed before fusion can be used. In this paper, we present a robust motion estimation algorithm which uses information from multiple receivers to estimate the relative motion between pings in the burst. We then compensate for motion, and show that the fusion of information from the burst of motion compensated pings improves both the resilience to noise and sonar accuracy, consequently increasing the operating range of the sonar system.
Generation of the basis sets for multi-Gaussian ultrasonic beam models—An overview
Authors: Kim Hak-Joon , Schmerr Lester W. , Sedov Alexander
Published: March 2006

By using a small number of Gaussian basis functions, one can synthesize the wave fields radiated from planar and focused piston transducers in the form of a superposition of Gaussian beams. Since Gaussian beams can be transmitted through complex geometries and media, such multi-Gaussian beam models have become powerful simulation tools. In previous studies the basis function expansion coefficients of multi-Gaussian beam models have been obtained by both spatial domain and k-space domain methods. Here, we will give an overview of these two methods and relate their expansion coefficients. We will demonstrate that the expansion coefficients that have been optimized for circular piston transducers can also be used to generate improved field simulations for rectangular probes. It will also be shown that because Gaussian beams are only approximate (paraxial) solutions to the wave equation, a multi-Gaussian beam model is ultimately limited in the accuracy it can obtain in the very near field.
High order approximate low frequency theory of elastic anisotropic lining and coating
Authors: Zakharov D. D.
Published: March 2006

A problem of the dynamic behavior of an elastic layer coupled to one or two thick elastic solids is considered. All the materials may possess a general anisotropy and the layer is assumed to be thin enough with respect to the characteristic wavelength. Introducing the asymptotic power series with respect to the thickness-over-wavelength ratio for the main quantities and using the asymptotic integration method the displacements and stresses on the layer surfaces are related. Thus, the so-called impedance boundary conditions (IBC) are deduced for three cases—for a coated substrate with given displacements or with given stresses on the surface and for two substrates with a layer in between. In contrast to previous papers these IBC are obtained for the most general situation with the asymptotic accuracy up to the sixth order, uniform with respect to the representation of the displacements and stresses. Presented theory can be used for studying the surface and interface phenomena as well as for calculating fields and spectra of layered solids. The results are validated numerically and compared with those of other authors.
Acoustical determination of the parameters governing viscous dissipation in porous media
Authors: Panneton Raymond , Olny Xavier
Published: March 2006

Analytical solutions are derived to extract from dynamic density the macroscopic parameters governing viscous dissipation of sound waves in open-cell porous media. While dynamic density is obtained from acoustical techniques, the analytical solutions are derived from the model describing this dynamic density. Here, semiphenomenological models by Johnson et al. and by Wilson are investigated. Assuming dynamic density, open porosity, and static airflow resistivity known, analytical solutions derived from the Johnson et al. model yield geometrical tortuosity and viscous characteristic dimension. For the Wilson model, only dynamic density needs to be known. In this case, analytical solutions yield—for the first time—Wilson's density parameter and vorticity-mode relaxation time. To alleviate constraints on the Johnson et al. model, an extrapolation approach is proposed to avoid prior knowledge of static resistivity. This approach may also be used to determine this latter parameter. The characterization methods are tested on three materials covering a wide range of static airflow resistivities (2300–150100Ns∕m4), frame rigidities (soft and rigid), and pore geometries (cells and fibers). It is shown that the analytical solutions can be used to assess the validity of the descriptive models for a given material.
Dual-probe laser interferometer for structural health monitoring
Authors: Hurlebaus Stefan , Jacobs Laurence J.
Published: March 2006

In this note we present the development of a dual-probe laser interferometer that uses the filtering properties of a polarized beamsplitter to enable two independent (uncoupled) detection probes. The robustness of this system is demonstrated by making broadband, noncontact, high fidelity measurements of Lamb waves in an aluminum plate.
Noncontact modal analysis of a pipe organ reed using airborne ultrasound stimulated vibrometry
Authors: Huber Thomas M. , Fatemi Mostafa , Kinnick Randy , Greenleaf James
Published: March 2006

The goal of this study was to excite and measure, in a noncontact manner, the vibrational modes of the reed from a reed organ pipe. To perform ultrasound stimulated excitation, the audio-range difference frequency between a pair of ultrasound beams produced a radiation force that induced vibrations. The resulting vibrational deflection shapes were measured with a scanning laser vibrometer. The resonances of any relatively small object can be studied in air using this technique. For a 36mm×6mm brass reed, displacements and velocities in excess of 5μm and 4mm∕s could be imparted at the fundamental frequency of 145Hz. Using the same ultrasound transducer, excitation across the entire range of audio frequencies was obtained. Since the beam was focused on the reed, ultrasound stimulated excitation eliminated background effects observed during mechanical shaker excitation, such as vibrations of clamps and supports. The results obtained using single, dual and confocal ultrasound transducers in AM and two-beam modes, along with results obtained using a mechanical shaker and audio excitation using a speaker are discussed.
Impedance of a sphere oscillating in an elastic medium with and without slip
Authors: Norris Andrew N.
Published: March 2006

The dynamic impedance of a sphere oscillating in an elastic medium is considered. Oestreicher’s [J. Acoust. Soc. Am. 23, 707–714 (1951)] formula for the impedance of a sphere bonded to the surrounding medium can be expressed in a relatively simple form in terms of three lumped impedances associated with the displaced mass and the longitudinal and transverse waves. If the surface of the sphere slips while the normal velocity remains continuous, the impedance formula is modified by adjusting the definition of the transverse impedance to include the interfacial impedance.
Sound generated by vortices in the presence of a porous half-cylinder mounted on a rigid plane
Authors: Lau C. K. , Tang S. K.
Published: March 2006

The sound generated by a single vortex and by two identical vortices in the presence of a half-cylinder made of porous material mounted on a rigid horizontal plane is studied theoretically using the acoustic analogy and the matched asymptotic expansion method. Both longitudinal and transverse dipoles are observed upon the introduction of the porous cylinder, but the former is considerably stronger than the latter in all the cases studied. Results suggest that the amplitudes of the dipoles and the overall acoustical energy radiated can be higher than that in the rigid cylinder case under some suitable combinations of flow parameters, especially when the flow resistance inside the porous material seen by the vortices is very small.
Perception of complex sounds in budgerigars (Melopsittacus undulatus) with temporary hearing loss
Authors: Dooling Robert J. , Ryals Brenda M. , Dent Micheal L. , Reid Tracy L.
Published: March 2006

Songbirds and parrots deafened as nestlings fail to develop normal vocalizations, while birds deafened as adults show a gradual deterioration in the quality and precision of vocal production. Beyond this, little is known about the effect of hearing loss on the perception of vocalizations. Here, we induced temporary hearing loss in budgerigars with kanamycin and tested several aspects of the hearing, including the perception of complex, species-specific vocalizations. The ability of these birds to discriminate among acoustically distinct vocalizations was not impaired but the ability to make fine-grain discriminations among acoustically similar vocalizations was affected, even weeks after the basilar papilla had been repopulated with new hair cells. Interestingly, these birds were initially unable to recognize previously familiar contact calls in a classification task—suggesting that previously familiar vocalizations sounded unfamiliar with new hair cells. Eventually, in spite of slightly elevated absolute thresholds, the performance of birds on discrimination and perceptual recognition of vocalizations tasks returned to original levels. Thus, even though vocalizations may initially sound different with new hair cells, there are only minimal long-term effects of temporary hearing loss on auditory perception, recognition of species-specific vocalizations, or other aspects of acoustic communication in these birds.
The method of waveform images for finite waveguides with resistive terminations subject to arbitrary initial conditions
Authors: Ginsberg Jerry H.
Published: March 2006

Reflection at normal incidence of a plane wave can be described by imaging the incident wave profile on the opposite side of the boundary. This concept has been introduced in a few texts, but only for nondissipative conditions. In this paper the procedure to describe a purely resistive boundary is generalized, and then the concept is extended to describe the transient response of a one-dimensional, finite length waveguide. The field generated by arbitrary initial conditions is characterized by an infinite number of images, which leads to a representation of the acoustic field as oppositely propagating waves in an unbounded waveguide. Both graphical and mathematical descriptions of these waves are derived, with the former shown to provide significant insights. Mathematical analysis of the image construction leads to identification of several fundamental acoustic phenomena, including acoustic modes and reverberation time. From an instructional viewpoint the ability to explore fundamental acoustic phenomena without recourse to solving differential equations makes the waveform image concept especially useful as an introductory tool.
Bubble pulsations between parallel plates
Authors: Cui Jianying , Hamilton Mark F. , Wilson Preston S. , Zabolotskaya Evgenia A.
Published: March 2006

The dynamic response of an acoustically driven spherical bubble between parallel plates is investigated in the linear approximation. For the case of rigid plates, explicit expressions are provided for the resonance frequency and damping, and the importance of including compressibility of the liquid is discussed. For wide channels, approximate results are presented that account for finite acoustic impedance of the plates.
The modeling of the radiation and response Green’s function of a fluid-loaded cylindrical shell with an external compliant layer
Authors: Cuschieri J. M.
Published: March 2006

Scattering and radiation of acoustic waves from a fluid-loaded cylindrical shell with an external compliant layer are of interest. The compliant layer can be modeled by a normally reacting impedance layer, which has the advantage that complex compliant layer geometries, such as partial compliant layers, can be considered. A question may, however, arise as to the accuracy of this approach. A more rigorous approach is to model the elastic shell and compliant layer using a multilayer shell theory, which has the disadvantage that it cannot be extended to consider partial layers. In this paper scattering results from the normally reacting compliant layer model are compared to those from the multilayer shell model to show that the two approaches produce similar results, except for thickness resonances of the compliant layer. Having established the consistency between the two approaches, results for the far-field acoustic radiation as a function of frequency and radiation angle for a fluid-loaded shell with an external compliant layer excited by an internal ring force are obtained using the normally reacting impedance layer model. These results clearly show the reduction in the far field radiation due to the presence of the compliant layer.
Vocal responses to unanticipated perturbations in voice loudness feedback: An automatic mechanism for stabilizing voice amplitude
Authors: Bauer Jay J. , Mittal Jay , Larson Charles R. , Hain Timothy C.
Published: March 2006

The present study tested whether subjects respond to unanticipated short perturbations in voice loudness feedback with compensatory responses in voice amplitude. The role of stimulus magnitude (±1,3 vs 6dB SPL), stimulus direction (up vs down), and the ongoing voice amplitude level (normal vs soft) were compared across compensations. Subjects responded to perturbations in voice loudness feedback with a compensatory change in voice amplitude 76% of the time. Mean latency of amplitude compensation was 157ms. Mean response magnitudes were smallest for 1-dB stimulus perturbations (0.75dB) and greatest for 6-dB conditions (0.98dB). However, expressed as gain, responses for 1-dB perturbations were largest and almost approached 1.0. Response magnitudes were larger for the soft voice amplitude condition compared to the normal voice amplitude condition. A mathematical model of the audio-vocal system captured the main features of the compensations. Previous research has demonstrated that subjects can respond to an unanticipated perturbation in voice pitch feedback with an automatic compensatory response in voice fundamental frequency. Data from the present study suggest that voice loudness feedback can be used in a similar manner to monitor and stabilize voice amplitude around a desired loudness level.
Compensation following real-time manipulation of formants in isolated vowels
Authors: Purcell David W. , Munhall Kevin G.
Published: March 2006

Auditory feedback influences human speech production, as demonstrated by studies using rapid pitch and loudness changes. Feedback has also been investigated using the gradual manipulation of formants in adaptation studies with whispered speech. In the work reported here, the first formant of steady-state isolated vowels was unexpectedly altered within trials for voiced speech. This was achieved using a real-time formant tracking and filtering system developed for this purpose. The first formant of vowel ∕ε∕ was manipulated 100% toward either /æ/ or /I/, and participants responded by altering their production with average F1 compensation as large as 16.3% and 10.6% of the applied formant shift, respectively. Compensation was estimated to begin <460ms after stimulus onset. The rapid formant compensations found here suggest that auditory feedback control is similar for both F0 and formants.
Dependence of phonation threshold pressure on vocal tract acoustics and vocal fold tissue mechanics
Authors: Chan Roger W. , Titze Ingo R.
Published: March 2006

Analytical and computer simulation studies have shown that the acoustic impedance of the vocal tract as well as the viscoelastic properties of vocal fold tissues are critical for determining the dynamics and the energy transfer mechanism of vocal fold oscillation. In the present study, a linear, small-amplitude oscillation theory was revised by taking into account the propagation of a mucosal wave and the inertive reactance (inertance) of the supraglottal vocal tract as the major energy transfer mechanisms for flow-induced self-oscillation of the vocal fold. Specifically, analytical results predicted that phonation threshold pressure (Pth) increases with the viscous shear properties of the vocal fold, but decreases with vocal tract inertance. This theory was empirically tested using a physical model of the larynx, where biological materials (fat, hyaluronic acid, and fibronectin) were implanted into the vocal fold cover to investigate the effect of vocal fold tissue viscoelasticity on Pth. A uniform-tube supraglottal vocal tract was also introduced to examine the effect of vocal tract inertance on Pth. Results showed that Pth decreased with the inertive impedance of the vocal tract and increased with the viscous shear modulus (G″) or dynamic viscosity (η′) of the vocal fold cover, consistent with theoretical predictions. These findings supported the potential biomechanical benefits of hyaluronic acid as a surgical bioimplant for repairing voice disorders involving the superficial layer of the lamina propria, such as scarring, sulcus vocalis, atrophy, and Reinke’s edema.
Cochlear transducer operating point adaptation
Authors: Zou Yuan , Zheng Jiefu , Ren Tianying , Nuttall Alfred
Published: March 2006

The operating point (OP) of outer hair cell (OHC) mechanotransduction can be defined as any shift away from the center position on the transduction function. It is a dc offset that can be described by percentage of the maximum transduction current or as an equivalent dc pressure in the ear canal. The change of OP can be determined from the changes of the second and third harmonics of the cochlear microphonic (CM) following a calibration of its initial value. We found that the initial OP was dependent on sound level and cochlear sensitivity. From CM generated by a lower sound level at 74dB SPL to avoid saturation and suppression of basal turn cochlear amplification, the OHC OP was at constant 57% of the maximum transduction current (an ear canal pressure of −0.1Pa). To perturb the OP, a constant force was applied to the bony shell of the cochlea at the 18kHz best frequency location using a blunt probe. The force applied over the scala tympani induced an OP change as if the organ of Corti moved toward the scala vestibuli (SV) direction. During an application of the constant force, the second harmonic of the CM partially recovered toward the initial level, which could be described by two time constants. Removing the force induced recovery of the second harmonic to its normal level described by a single time constant. The force applied over the SV caused an opposite result. These data indicate an active mechanism for OHC transduction OP.
The influence of perceived sexual orientation on fricative identification
Authors: Munson Benjamin , Jefferson Sarah V. , McDonald Elizabeth C.
Published: March 2006

Listeners are more likely to hear a synthetic fricative ambiguous between /s/ and /ʃ/ as /ʃ/ if it is appended to a woman’s voice than a man’s voice [Strand and Johnson, in Natural Language Processing and Speech Technology: Results of the 3rd KONVENS Conference (Mouton de Gruyter, Berlin, 1996), pp. 14–26]. This study expanded on this finding by replicating the result with a much larger group of male and female talkers than had been examined previously, by examining whether phonetic context mediates the influence of talker sex on fricative identification, and by examining whether talkers’ perceived sexual orientation influences fricative identification. Stimuli were created by pairing a synthetic nine-step /s/-/ʃ/ continuum with tokens of /æk/ and /ɪp/ taken from productions of shack and ship by 44 talkers whose perceived sexual orientation had been reported previously [Munson et al., J. Phonetics (in press)]. Listeners participated in a series of two-alternative sack-shack and sip-ship identification experiments. Listeners identified more /ʃ/ tokens for women’s voices than for men’s voices for both continua. Lesbian/bisexual-sounding women elicited more sack and sip responses than heterosexual-sounding women. No consistent influence of perceived sexual orientation on fricative identification was noted for men’s voices. Results suggest that listeners are sensitive to the association between fricatives’ center frequencies and perceived sexual orientation in women’s voices, but not in men’s voices.
The ability of listeners to use recovered envelope cues from speech fine structure
Authors: Gilbert Gaëtan , Lorenzi Christian
Published: March 2006

Recent work has demonstrated that auditory filters recover temporal-envelope cues from speech fine structure when the former were removed by filtering or distortion. This study extended this work by assessing the contribution of recovered envelope cues to consonant perception as a function of the analysis bandwidth, when vowel-consonant-vowel (VCV) stimuli were processed in order to keep their fine structure only. The envelopes of these stimuli were extracted at the output of a bank of auditory filters and applied to pure tones whose frequency corresponded to the original filters’ center frequencies. The resulting stimuli were found to be intelligible when the envelope was extracted from a single, wide analysis band. However, intelligibility decreases from one to eight bands with no further decrease beyond this value, indicating that the recovered envelope cues did not play a major role in consonant perception when the analysis bandwidth was narrower than four times the bandwidth of a normal auditory filter (i.e., number of analysis bands ⩾8 for frequencies spanning 80to8020Hz).
On using polynomial chaos for modeling uncertainty in acoustic propagation
Authors: Creamer Dennis B.
Published: March 2006

The use of polynomial chaos for incorporating environmental variability into propagation models is investigated in the context of a simplified one-dimensional model, which is relevant for acoustic propagation when the random sound speed is independent of depth. Environmental variability is described by a spectral representation of a stochastic process and the chaotic representation of the wave field then consists of an expansion in terms of orthogonal random polynomials. Issues concerning implementation of the relevant equations, the accuracy of the approximation, uniformity of the expansion over the propagation range, and the computational burden necessary to evaluate different field statistics are addressed. When the correlation length of the environmental fluctuations is small, low-order expansions work well, while for large correlation lengths the convergence of the expansion is highly range dependent and requires high-order approximants. These conclusions also apply in higher-dimensional propagation problems.
Age-related changes in within- and between-channel gap detection using sinusoidal stimuli
Authors: Heinrich Antje , Schneider Bruce
Published: March 2006

Pure tone gap stimuli with identical (within-channel) or dissimilar (between-channel) marker frequencies of 1 and 2kHz were presented to young and old listeners in a two-interval forced choice gap detection task. To estimate the influence of extraneous duration cues on gap detection, thresholds in the between-channel conditions were obtained for two different sets of reference stimuli: reference stimuli that were matched to the overall duration of the gap stimulus, i.e., two markers plus the gap, and reference stimuli that were fixed at the combined duration of the two markers excluding the gap. Results from within-channel conditions were consistent with previous studies, i.e., there were small but highly reliable age differences, smaller gap thresholds at longer marker durations, and an interaction between the two variables. In between-channel conditions, however, age differences were not as clear cut. Rather, the effect of age varied as a function of duration cue and was more pronounced when stimuli were matched for overall duration than when the duration of the reference tone was fixed.
A theoretical model to predict the low-frequency sound absorption of a Helmholtz resonator array
Authors: Kim SangRyul , Kim Yang-Hann , Jang Jae-Hee
Published: March 2006

A theoretical method based on mutual radiation impedance is proposed to compute the sound absorption performance of a Helmholtz resonator array in the low-frequency range. Any configuration of resonator arrangement can be allowed in the method, while all the resonators may or may not be identical. Comparisons of the theoretical predictions with those done by the past studies or experiments show that the present method can accurately predict the absorption performance in more general cases.
Investigation of superharmonic sound propagation and imaging in biological tissues in vitro
Authors: Ma Qingyu , Zhang Dong , Gong Xiufen , Ma Yong
Published: March 2006

This article presents both theoretical and experimental studies on the superharmonic generation and its imaging in biological tissues. A superharmonic component is defined as a summation of the third-, fourth-, and fifth-order harmonics. A superharmonic signal is produced using an 8-mm-diam, 2.5-MHz planar piston source that is excited by eight-cycle, 2.5-MHz tone bursts. Axial and lateral field distributions of the superharmonic component and the second harmonic are first calculated based on the nonlinear KZK model and then compared with those experimentally determined at two different source pressures of 0.5 and 1MPa. Results indicate that the amplitude of the superharmonic component can exceed that of the second harmonic, depending on the axial distance and the fundamental pressure amplitude. Also, the 3-dB beamwidth of the superharmonic component is about 23% narrower than that of the second harmonic. Additional experiments are performed in vitro using liver and fatty tissues in transmission mode and produced two-dimensional images using the fundamental, the second harmonic, and the superharmonic signals. Although the clinical applicability of this work still needs to be assessed, these results indicate that the superharmonic image quality is better than that of the other two images.
Binaural detection with narrowband and wideband reproducible noise maskers. III. Monaural and diotic detection and model results
Authors: Davidson Sean A. , Gilkey Robert H. , Colburn H. Steven , Carney Laurel H.
Published: March 2006

A single-interval, yes-no, tone-in-noise detection experiment was conducted to measure the proportion of “tone present” responses to each of 25 reproducible noise-alone and tone-plus-noise waveforms under narrowband (100Hz), wideband (2900Hz), monotic, and diotic stimulus conditions. Proportions of “tone present” responses (estimates of the probabilities of hits and false alarms) were correlated across masker bandwidths and across monotic and diotic conditions. Two categories of models were considered; one based on stimulus energy or neural counts, and another based on temporal structure of the stimulus envelope or neural patterns. Both categories gave significant correlation between decision variables and data. A model based on a weighted combination of energy in multiple critical bands performed best, predicting up to 90% of the variance in the reproducible-noise data. However, since energy-based models are unable to successfully explain detection under a roving-level paradigm without substantial modification, it is argued that other variations of detection models must be considered for future study. Temporal models are resistant to changes in threshold under roving-level conditions, but explained at most only 67% of the variance in the reproducible-noise data.
Effect of the glottal source and the vocal tract on the partials amplitude of vibrato in male voices
Authors: Arroabarren Ixone , Carlosena Alfonso
Published: March 2006

In this paper the production of vocal vibrato is investigated. The most relevant features of the acoustical vibrato signal, frequency and amplitude variations of the partials, will be related to the voice production features, glottal source (GS) and vocal tract response (VTR). Unlike previous related works, in this approach, the effect on the amplitude variations of the partials of each one of the above-mentioned voice production features will be identified in recordings of natural singing voice. Moreover, we will take special care of the reliability of the measurements, and, to this aim, a noninteractive vibrato production model will be also proposed in order to describe the vibrato production process and, more importantly, validate the measurements carried out in natural vibrato. Based on this study, it will be shown that during a few vibrato cycles, the glottal pulse characteristics, as well as the VTR, do not significantly change, and only the fundamental frequency of the GS varies. As a result, the pitch variations can be attributed to the GS, and these variations, along with the vocal tract filtering effect, will result in frequency and amplitude variations of the acoustic signal partials.
Cochlear compression wave: An implication of the Allen-Fahey experiment
Authors: Ren Tianying , Nuttall Alfred L.
Published: March 2006

In order to measure the gain of the cochlear amplifier, de Boer and co-workers recently extended the Allen-Fahey experiment by measuring otoacoustic emissions and basilar membrane vibration [J. Acoust. Soc. Am. 117, 1260–1266 (2005)]. Although this new experiment overcame the limitation of the original Allen-Fahey experiment for using a low-frequency ratio, it confirmed the previous finding that there is no detectable cochlear amplification. This result was attributed to destructive interference of the otoacoustic emission over its generation site. The present letter provides an alternative interpretation of the results of the Allen-Fahey experiment based on the cochlear fluid compression-wave theory.
Quantitative measurements of acoustic emissions from cavitation at the surface of a stone in response to a lithotripter shock wave
Authors: Chitnis Parag V. , Cleveland Robin O.
Published: March 2006

Measurements are presented of acoustic emissions from cavitation collapses on the surface of a synthetic kidney stone in response to shock waves (SWs) from an electrohydraulic lithotripter. A fiber optic probe hydrophone was used for pressure measurements, and passive cavitation detection was used to identify acoustic emissions from bubble collapse. At a lithotripter charging voltage of 20kV, the focused SW incident on the stone surface resulted in a peak pressure of 43±6MPa compared to 23±4MPa in the free field. The focused SW incident upon the stone appeared to be enhanced due to the acoustic emissions from the forced cavitation collapse of the preexisting bubbles. The peak pressure of the acoustic emission from a bubble collapse was 34±15MPa, that is, the same magnitude as the SWs incident on the stone. These data indicate that stresses induced by focused SWs and cavitation collapses are similar in magnitude thus likely play a similar role in stone fragmentation.
Loudness of brief tones measured by magnitude estimation and loudness matching
Authors: Epstein Michael , Florentine Mary
Published: March 2006

McFadden [J. Acoust. Soc. Am. 57, 702–704 (1975)] questioned the accuracy and reliability of magnitude estimation for measuring loudness of tones that vary both in duration and level, whereas Stevens and Hall [Percept. Psychophys. 1, 319–327 (1966)] reported reasonable group data. To gain insight into this discrepancy, the present study compares loudness measures for 5- and 200-ms tones using magnitude estimation and equal-loudness matches from the same listeners. Results indicate that both procedures provide rapid and accurate assessments of group loudness functions for brief tones, but may not be reliable enough to reveal specific characteristics of loudness in individual listeners.
Vibro-acoustic control with a distributed sensor network
Authors: Frampton Kenneth D.
Published: March 2006

The purpose of this work is to demonstrate the ability of a distributed control system, based on a smart sensor network, to reduce acoustic radiation from a vibrating structure. The platform from which control is effected consists of a network of smart sensors, each referred to as a node. Each node possesses its own computational capability, sensor, actuator and the ability to communicate with other nodes via a wired or wireless network. The primary focus of this work is to employ existing group management middleware concepts to enable vibro-acoustic control with such a distributed network. Group management middleware is distributed software that provides for the establishment and maintenance of groups of distributed nodes and that provides for the network communication among such groups. The control objective is met by designing distributed feedback compensators that take advantage of node groups in order to effect their control. The node groups are formed based on physical proximity. The global control objective is to minimize the radiated sound power from a rectangular plate. Results of this investigation demonstrate that such a distributed control system can achieve attenuations comparable to those achieved by a centralized controller.
Resonant modes in transiently evoked otoacoustic emissions and asymmetries between left and right ear
Authors: Jedrzejczak W. Wiktor , Blinowska Katarzyna J. , Konopka Wieslaw
Published: March 2006

A number of single-frequency resonant modes in click evoked otoacoustic emissions (OAEs) was investigated. The OAE modes were identified by means of an adaptive approximation method based on the matching pursuit (MP) algorithm. The signals were decomposed into basic waveforms coming from a very large and redundant dictionary of Gabor functions. The study was performed on transiently evoked otoacoustic emissions (TEOAEs) from left and right ears of 108 subjects. The correspondence between waveforms found by the procedure and resonant modes was shown (both for simulated noisy data and for single-person TEOAEs). The decomposition of TEOAEs made distinction between short and long-lasting components possible. The number of main resonant modes was studied by means of different criteria and they all led to similar results, indicating that the main features of the signal are explained on average by 10 waveforms. The same number of resonant modes for the right ear accounted for more energy than for the left ear.
Effects of introducing unprocessed low-frequency information on the reception of envelope-vocoder processed speech
Authors: Qin Michael K. , Oxenham Andrew J.
Published: March 2006

This study investigated the benefits of adding unprocessed low-frequency information to acoustic simulations of cochlear-implant processing in normal-hearing listeners. Implant processing was simulated using an eight-channel noise-excited envelope vocoder, and low-frequency information was added by replacing the lower frequency channels of the processor with a low-pass-filtered version of the original stimulus. Experiment 1 measured sentence-level speech reception as a function of target-to-masker ratio, with either steady-state speech-shaped noise or single-talker maskers. Experiment 2 measured listeners’ ability to identify two vowels presented simultaneously, as a function of the F0 difference between the two vowels. In both experiments low-frequency information was added below either 300 or 600Hz. The introduction of the additional low-frequency information led to substantial and significant improvements in performance in both experiments, with a greater improvement observed for the higher (600Hz) than for the lower (300Hz) cutoff frequency. However, performance never equaled performance in the unprocessed conditions. The results confirm other recent demonstrations that added low-frequency information can provide significant benefits in intelligibility, which may at least in part be attributed to improvements in F0 representation. The findings provide further support for efforts to make use of residual acoustic hearing in cochlear-implant users.
Perceptual learning in speech: Stability over time
Authors: Eisner Frank , McQueen James M.
Published: March 2006

Perceptual representations of phonemes are flexible and adapt rapidly to accommodate idiosyncratic articulation in the speech of a particular talker. This letter addresses whether such adjustments remain stable over time and under exposure to other talkers. During exposure to a story, listeners learned to interpret an ambiguous sound as [f] or [s]. Perceptual adjustments measured after 12h were as robust as those measured immediately after learning. Equivalent effects were found when listeners heard speech from other talkers in the 12h interval, and when they had the opportunity to consolidate learning during sleep.