bluuebunny/crossref_metadata_2025 huggingface dataset:
Material properties of euphausiids and other zooplankton from the Bering Sea
Authors: Smith Joy N. , Ressler Patrick H. , Warren Joseph D.
Published: November 2010

Acoustic assessment of Bering Sea euphausiids and their predators can provide useful data for ecosystem studies if the acoustic scattering characteristics of these animals are known. The amount of acoustic energy that is scattered by different marine zooplankton taxa is strongly affected by the contrast of the animal’s density (g) and sound speed (h) with the surrounding seawater. Density and sound speed contrast were measured in the Bering Sea during the summer of 2008 for several different zooplankton and nekton taxa including: euphausiids (Thysanoessa inermis, Thysanoessa raschii, and Thysanoessa spinifera), copepods, amphipods, chaetognaths, gastropods, fish larvae, jellyfish, and squid. Density contrast values varied between different taxa as well as between individual animals within the same species. Sound speed contrast was measured for monospecific groups of animals and differences were found among taxa. The range, mean, and standard deviation of g and h for all euphausiid species were: g=1.001–1.041; 1.018±0.009 and h=0.990–1.017; 1.006±0.008. Changes in the relationship between euphausiid material properties and animal length, seawater temperature, seawater density, and geographic location were also evaluated. Results suggest that environmental conditions at different sample locations led to significant differences in animal density and material properties.
Active sound transmission control of a double-panel module using decoupled analog feedback control: Experimental results
Authors: Sagers Jason D. , Leishman Timothy W. , Blotter Jonathan D.
Published: November 2010

Low-frequency sound transmission through passive lightweight partitions often renders them ineffective as means of sound isolation. As a result, researchers have investigated actively controlled lightweight partitions in an effort to remedy this problem. One promising approach involves active segmented partitions (ASPs), in which partitions are segmented into several distinctly controlled modules. This paper provides an experimental analysis of a double-panel ASP module wherein the source- and transmitting-side panels are independently controlled by an analog feedback controller. Experimental results, including plant frequency response functions, acoustic coupling strengths, frequency response functions, and transmission losses (TLs) of single- and double-panel modules, are presented and compared to numerical predictions. Over the bandwidth of 20 Hz to 1 kHz, the average measured TL for an actively controlled single-panel module was 29 dB, compared to 14 dB for the passive case. The average measured TL over the same bandwidth for the actively controlled double-panel module was 57 dB, compared to 31 dB for the passive case.
Build-up of the tendency to segregate auditory streams: Resetting effects evoked by a single deviant tone
Authors: Haywood Nicholas R. , Roberts Brian
Published: November 2010

The tendency to hear a sequence of alternating low (L) and high (H) frequency tones as two streams can be increased by a preceding induction sequence, even one composed only of same-frequency tones. Four experiments used such an induction sequence (10 identical L tones) to promote segregation in a shorter test sequence comprising L and H tones. Previous studies have shown that the build-up of stream segregation is usually reduced greatly when a sudden change in acoustic properties distinguishes all of the induction tones from their test-sequence counterparts. Experiment 1 showed that a single deviant tone, created by altering the final inducer (in frequency, level, duration, or replacement with silence) reduced reported segregation, often substantially. Experiment 2 partially replicated this finding, using changes in temporal discrimination as a measure of streaming. Experiments 3 and 4 varied the size of a frequency change applied to the deviant tone; the extent of resetting varied with size only gradually. The results suggest that resetting begins to occur once the change is large enough to be noticeable. Since the prior inducers always remained unaltered in the deviant-tone conditions, it is proposed that a single change actively resets the build-up evoked by the induction sequence.
Spanish listeners’ perception of American and Southern British English vowels
Authors: Escudero Paola , Chládková Kateřina
Published: November 2010

L2 studies demonstrate that learners differ in their speech perception patterns. Recent explanations attribute this variation to the different initial stages with which learners start their L2 development. Spanish listeners’ categorization of Standard Southern British English and American English vowels is compared. The results show that, on the basis of steady-state F1 and F2 values, listeners classify the vowels of these two English varieties differently. This finding suggests that the dialect to which learners are exposed determines their initial stage for L2 perception and the tasks they need to perform to successfully acquire a new sound system.
A direct approach for the design of chirp stimuli used for the recording of auditory brainstem responses
Authors: Elberling Claus , Don Manuel
Published: November 2010

A recent study evaluates auditory brainstem responses (ABRs) evoked by chirps of different durations (sweeping rates) [Elberling et al. (2010). J. Acoust. Soc. Am. 128, 215–223]. The study demonstrates that shorter chirps are most efficient at higher levels of stimulation whereas longer chirps are most efficient at lower levels. Mechanisms other than the traveling wave delay, in particular, upward spread of excitation and changes in cochlear-neural delay with level, are suggested to be responsible for these findings. As a consequence, delay models based on estimates of the traveling wave delay are insufficient for the design of chirp stimuli, and another delay model based on a direct approach is therefore proposed. The direct approach uses ABR-latencies from normal-hearing subjects in response to octave-band chirps over a wide range of levels. The octave-band chirps are constructed by decomposing a broad-band chirp, and constitute a subset of the chirp. The delay compensations of the proposed model are similar to those found in the previous experimental study, which thus verifies the results of the proposed model.
Covariance-based approaches to aeroacoustic noise source analysis
Authors: Du Lin , Xu Luzhou , Li Jian , Guo Bin , Stoica Petre , Bahr Chris , Cattafesta Louis N.
Published: November 2010

In this paper, several covariance-based approaches are proposed for aeroacoustic noise source analysis under the assumptions of a single dominant source and all observers contaminated solely by uncorrelated noise. The Cramér-Rao Bounds (CRB) of the unbiased source power estimates are also derived. The proposed methods are evaluated using both simulated data as well as data acquired from an airfoil trailing edge noise experiment in an open-jet aeroacoustic facility. The numerical examples show that the covariance-based algorithms significantly outperform an existing least-squares approach and provide accurate power estimates even under low signal-to-noise ratio (SNR) conditions. Furthermore, the mean-squared-errors (MSEs) of the so-obtained estimates are close to the corresponding CRB especially for a large number of data samples. The experimental results show that the power estimates of the proposed approaches are consistent with one another as long as the core analysis assumptions are obeyed.
Approximate transducer transient suppression with increased output amplitude
Authors: Piquette Jean C.
Published: November 2010

A technique for the rapid, smooth turn-on of a transducer is described. The method is based on a previously described technique [J. C. Piquette, J. Acoust. Soc. Am. 92, 1203–1213 (1992)]. In the previous method, transducer output amplitude is severely reduced compared to that obtained when driving the transducer using a standard gated sine due to the presence of a ramp component in the transient-suppressing voltage waveform. In the present work, approximate methods that eliminate the ramp component are described. Eliminating the ramp component results in significantly greater output amplitude, although the level of transient suppression that is achieved is not as good as that seen when using the exact transient-suppressing drive. Nonetheless, the smoothness (i.e., lack of spikes) in the transducer response is not compromised by the approximations.
Shear waves in viscoelastic wormlike micellar fluids
Authors: Gladden J. R. , Skelton C. E. , Mobley J.
Published: November 2010

Low frequency (61 Hz) shear wave speeds have been measured in viscoelastic wormlike micellar (WM) fluids for a concentration range of 20/12–160/96 mM CTAB/NaSAL. The strain induced birefringence of the WM fluids was exploited to optically track the shear pulse using crossed polarizing filters and high speed video. It was found that shear speed increases roughly linearly with concentration at a rate of 3.5 mm s−1 mM−1 CTAB. Further, comparison with elastic and loss moduli obtained from rheology data show that shear wave propagation is dominated by the elastic modulus for this frequency range.
Vibration in a self-oscillating vocal fold model with left-right asymmetry in body-layer stiffness
Authors: Zhang Zhaoyan
Published: November 2010

This study compares the phonatory behavior of an asymmetric vocal fold model to that of each individual vocal fold model in a hemi-configuration. Although phonation frequencies of the two folds in hemi-configurations had a ratio close to 1:3, a subharmonic synchronization between the two folds was not observed in the asymmetric model. Instead, the vibratory behavior was dominated by the dynamics of one fold only, and the other fold was enslaved to vibrate at the same frequency. Increasing subglottal pressure induced a shift in relative dominance between the two folds, leading to abrupt changes in both vibratory pattern and frequency.
Propagation-invariant classification of sounds in channels with dispersion and absorption
Authors: Okopal Greg , Loughlin Patrick J.
Published: November 2010

In a previous paper [G. Okopal et al., J. Acoust. Soc. Am. 123, 832–841 (2008)], a method to obtain features of a wave that are unaffected by dispersion, per mode, was developed for improving classification of underwater sounds (e.g., sonar backscatter). The current paper builds on this work and presents additional contributions. First, it is shown that the dispersion-invariant moments developed previously are not invariant to frequency-dependent attenuation (absorption); consequently, their classification performance degrades in such channels. Second, a feature extraction method is developed to obtain features that are invariant to dispersion, and to two forms of absorption (known a priori): namely, absorption that yields spectral magnitude attenuation (in dB) that is linear with frequency, and linear with log-frequency. Third, the relationship of these absorption- and dispersion-invariant moment (ADIM) features to the cepstrum of the wave is examined, and it is shown that cepstral moments are also invariant to dispersion, and to the first form of absorption for odd-order moments. Finally, simulations are conducted to illustrate the performance of the ADIMs and cepstral moments on classifying the backscatter from steel shells in a dispersive channel with absorption. Receiver operator characteristic curves quantify the superior discriminability of the ADIMs and cepstral moments compared to ordinary moments.
Modulation detection for amplitude-modulated bone-conducted sounds with sinusoidal carriers in the high- and ultrasonic-frequency range
Authors: Hotehama Takuya , Nakagawa Seiji
Published: November 2010

Ultrasonic vibration generates a sensation of sound via bone-conduction. This phenomenon is called bone-conducted ultrasonic (BCU) hearing. Complex sounds can also be perceived by amplitude-modulating a BCU stimulus (AM-BCU). The influence of the modulation frequency on the sensitivity to detecting amplitude modulation of sinusoidal carriers of 10, 20, and 30 kHz was examined to clarify the characteristics of the perception of amplitude modulation over the sonic or audio-frequency range and the ultrasonic range. In addition, the detection sensitivity for single-sideband modulation for a 20 kHz carrier was measured. Temporal modulation transfer functions (TMTFs) obtained at each carrier frequency suggest that the auditory system has the ability to process timing information in the envelopes of AM-BCUs at lower modulation frequencies, as is the case with audio-frequency sounds. The possible influence of peripheral filtering on the shape of the TMTF at higher frequencies was examined.
Electroglottographic wavegrams: A technique for visualizing vocal fold dynamics noninvasively
Authors: Herbst Christian T. , Fitch W. Tecumseh S. , Švec Jan G.
Published: November 2010

A method for analyzing and displaying electroglottographic (EGG) signals (and their first derivative, DEGG) is introduced: the electroglottographic wavegram (“wavegram” hereafter). To construct a wavegram, the time-varying fundamental frequency is measured and consecutive individual glottal cycles are identified. Each cycle is locally normalized in duration and amplitude, the signal values are encoded by color intensity and the cycles are concatenated to display the entire voice sample in a single image, similar as in sound spectrography. The wavegram provides an intuitive means for quickly assessing vocal fold contact phenomena and their variation over time. Variations in vocal fold contact appear here as a sequence of events rather than single phenomena, taking place over a certain period of time, and changing with pitch, loudness and register. Multiple DEGG peaks are revealed in wavegrams to behave systematically, indicating subtle changes of vocal fold oscillatory regime. As such, EGG wavegrams promise to reveal more information on vocal fold contacting and de-contacting events than previous methods.
Effects of consonant-vowel intensity ratio on loudness of monosyllabic words
Authors: Orr Suzanne B. , Montgomery Allen A. , Healy Eric W. , Dubno Judy R.
Published: November 2010

Previous research has suggested that speech loudness is determined primarily by the vowel in consonant-vowel-consonant (CVC) monosyllabic words, and that consonant intensity has a negligible effect. The current study further examines the unique aspects of speech loudness by manipulating consonant-vowel intensity ratios (CVRs), while holding the vowel constant at a comfortable listening level (70 dB), to determine the extent to which vowels and consonants contribute differentially to the loudness of monosyllabic words with voiced and voiceless consonants. The loudness of words edited to have CVRs ranging from −6 to +6 dB was compared to that of standard words with unaltered CVR by 10 normal-hearing listeners in an adaptive procedure. Loudness and overall level as a function of CVR were compared for four CVC word types: both voiceless consonants modified; only initial voiceless consonants modified; both voiced consonants modified; and only initial voiced consonants modified. Results indicate that the loudness of CVC monosyllabic words is not based strictly on the level of the vowel; rather, the overall level of the word and the level of the vowel contribute approximately equally. In addition to furthering the basic understanding of speech perception, the current results may be of value for the coding of loudness by hearing aids and cochlear implants.
Across-talker effects on non-native listeners’ vowel perception in noise
Authors: Bent Tessa , Kewley-Port Diane , Ferguson Sarah Hargus
Published: November 2010

This study explored how across-talker differences influence non-native vowel perception. American English (AE) and Korean listeners were presented with recordings of 10 AE vowels in /bVd/ context. The stimuli were mixed with noise and presented for identification in a 10-alternative forced-choice task. The two listener groups heard recordings of the vowels produced by 10 talkers at three signal-to-noise ratios. Overall the AE listeners identified the vowels 22% more accurately than the Korean listeners. There was a wide range of identification accuracy scores across talkers for both AE and Korean listeners. At each signal-to-noise ratio, the across-talker intelligibility scores were highly correlated for AE and Korean listeners. Acoustic analysis was conducted for 2 vowel pairs that exhibited variable accuracy across talkers for Korean listeners but high identification accuracy for AE listeners. Results demonstrated that Korean listeners’ error patterns for these four vowels were strongly influenced by variability in vowel production that was within the normal range for AE talkers. These results suggest that non-native listeners are strongly influenced by across-talker variability perhaps because of the difficulty they have forming native-like vowel categories.
A hybrid modal analysis for enclosed sound fields
Authors: Xu Buye , Sommerfeldt Scott D.
Published: November 2010

A hybrid modal expansion that combines the free field Green’s function and a modal expansion will be presented in this paper based on a review and an extension of the existing modal analysis theories for the sound field in enclosures. The enclosed sound field will be separated into the direct field and reverberant field, which have been treated together in the traditional modal analysis. Studies on a point source in rectangular enclosures show that the hybrid modal expansion converges notably faster than the traditional modal expansions, especially in the region near the source, and introduces much smaller errors with a limited number of modes. The hybrid modal expansion can be easily applied to complex sound sources if the free field responses of the sources are known. Damped boundaries are also considered in this paper, and a set of modified modal functions is introduced, which is shown to be suitable for many damped boundary conditions.
An investigation of the relation between sibilant production and somatosensory and auditory acuity
Authors: Ghosh Satrajit S. , Matthies Melanie L. , Maas Edwin , Hanson Alexandra , Tiede Mark , Ménard Lucie , Guenther Frank H. , Lane Harlan , Perkell Joseph S.
Published: November 2010

The relation between auditory acuity, somatosensory acuity and the magnitude of produced sibilant contrast was investigated with data from 18 participants. To measure auditory acuity, stimuli from a synthetic sibilant continuum ([s]-[ʃ]) were used in a four-interval, two-alternative forced choice adaptive-staircase discrimination task. To measure somatosensory acuity, small plastic domes with grooves of different spacing were pressed against each participant’s tongue tip and the participant was asked to identify one of four possible orientations of the grooves. Sibilant contrast magnitudes were estimated from productions of the words ‘said,’ ‘shed,’ ‘sid,’ and ‘shid’. Multiple linear regression revealed a significant relation indicating that a combination of somatosensory and auditory acuity measures predicts produced acoustic contrast. When the participants were divided into high- and low-acuity groups based on their median somatosensory and auditory acuity measures, separate ANOVA analyses with sibilant contrast as the dependent variable yielded a significant main effect for each acuity group. These results provide evidence that sibilant productions have auditory as well as somatosensory goals and are consistent with prior results and the theoretical framework underlying the DIVA model of speech production.
Evaluation of the vibrational modes of the human skull as it relates to bone-conducted sound
Authors: Wismer Margaret G. , O’Brien William D.
Published: November 2010

Analytic and numerical models are used to study bone-conducted sound and how it relates to the vibrational modes of the human skull. The analytic model is based on the solution to the acoustic and elastic wave equations and the constraining boundary conditions for a fluid-filled elastic sphere. Both models predict that most of the acoustic energy of bone-conducted sound exists in the form of surface wave vibrations at the interface between two acoustic media rather than in the bone or cranial chamber. These surface waves have phase speeds much slower than the bulk sound speed for bone. The analytic model, based on spherical elastic shells, predicts a phase speed of 775 m/s and the first resonance frequency at 1500 Hz while the numerical solution yields approximate phase speeds of 450 m/s and provides a visual display of the surface waves and diffraction effects.
A multiscale model for array of capacitive micromachined ultrasonic transducers
Authors: Meynier Cyril , Teston Franck , Certon Dominique
Published: November 2010

A model is developed for studying the acoustic behavior of a cMUT array. This model is based on separate calculations of the terms describing the behavior of a single cMUT on one hand, and those corresponding to acoustic mutual coupling on the other hand. The terms are combined into an equivalent circuit with matrix terms which displays only one degree of freedom per cell. This approach allows the simulation of several dozen cMUTs considered individually with a very short computer time. A Finite Difference model is used for the simulation of an isolated cell radiating acoustic energy and the determination of its equivalent electromechanical circuit. It is shown for various mutual coupling situations that the coupling between cells can be correctly approximated using a very simple mutual impedance term. The model is compared with experimental results, using a set of different cMUT configurations. Experimental results were obtained with electrical impedancemetry and laser interferometry techniques performed in fluid immersion.
The effect of signal duration on the underwater detection thresholds of a harbor porpoise (Phocoena phocoena) for single frequency-modulated tonal signals between 0.25 and 160 kHz
Authors: Kastelein Ronald A. , Hoek Lean , de Jong Christ A. F. , Wensveen Paul J.
Published: November 2010

The underwater hearing sensitivity of a young male harbor porpoise for tonal signals of various signal durations was quantified by using a behavioral psychophysical technique. The animal was trained to respond only when it detected an acoustic signal. Fifty percent detection thresholds were obtained for tonal signals (15 frequencies between 0.25–160 kHz, durations 0.5–5000 ms depending on the frequency; 134 frequency-duration combinations in total). Detection thresholds were quantified by varying signal amplitude by the 1-up 1-down staircase method. The hearing thresholds increased when the signal duration fell below the time constant of integration. The time constants, derived from an exponential model of integration [Plomp and Bouman, J. Acoust. Soc. Am. 31, 749–758 (1959)], varied from 629 ms at 2 kHz to 39 ms at 64 kHz. The integration times of the porpoises were similar to those of other mammals including humans, even though the porpoise is a marine mammal and a hearing specialist. The results enable more accurate estimations of the distances at which porpoises can detect short-duration environmental tonal signals. The audiogram thresholds presented by Kastelein et al. [J. Acoust. Soc. Am. 112, 334–344 (2002)], after correction for the frequency bandwidth of the FM signals, are similar to the results of the present study for signals of 1500 ms duration. Harbor porpoise hearing is more sensitive between 2 and 10 kHz, and less sensitive above 10 kHz, than formerly believed.
A principal components model of soundscape perception
Authors: Axelsson Östen , Nilsson Mats E. , Berglund Birgitta
Published: November 2010

There is a need for a model that identifies underlying dimensions of soundscape perception, and which may guide measurement and improvement of soundscape quality. With the purpose to develop such a model, a listening experiment was conducted. One hundred listeners measured 50 excerpts of binaural recordings of urban outdoor soundscapes on 116 attribute scales. The average attribute scale values were subjected to principal components analysis, resulting in three components: Pleasantness, eventfulness, and familiarity, explaining 50, 18 and 6% of the total variance, respectively. The principal-component scores were correlated with physical soundscape properties, including categories of dominant sounds and acoustic variables. Soundscape excerpts dominated by technological sounds were found to be unpleasant, whereas soundscape excerpts dominated by natural sounds were pleasant, and soundscape excerpts dominated by human sounds were eventful. These relationships remained after controlling for the overall soundscape loudness (Zwicker’s N10), which shows that ‘informational’ properties are substantial contributors to the perception of soundscape. The proposed principal components model provides a framework for future soundscape research and practice. In particular, it suggests which basic dimensions are necessary to measure, how to measure them by a defined set of attribute scales, and how to promote high-quality soundscapes.
The effects of long-term exposure to railway and road traffic noise on subjective sleep disturbance
Authors: Hong Jiyoung , Kim Jaehwan , Lim Changwoo , Kim Kyutae , Lee Soogab
Published: November 2010

The exposure-response relationships between subjective annoyance with sleep disturbance from railway trains and road traffic noise were established from an extensive social survey by CENVR (Center for Environmental Noise and Vibration Research) in Korea. The objectives of this research are to determine the long-term effects of noise on sleep and to compare the exposure-response relationships from different noise sources with those from other studies and to elucidate the effects of some modifying factors on subjective responses to noise. From an investigation of the percentage of a highly sleep-disturbed population (%HSD) in response to railway and road traffic noise, it was found that sleep is affected more by railway noise than by road traffic noise. The effects of non-acoustical factors on the responses were examined and sensitivity was shown to be a significant modifying factor, as it pertains to subjective sleep disturbance. A comparison of the response curves from an analysis of pooled data from predominantly European surveys by Miedema and Vos [Behav. Sleep Med. 5, 1–20 (2007)] with the response curves from this survey showed more of a subjective sleep disturbance response in this survey to railway noise, whereas there was no significant difference in terms of a response to road traffic noise.
Acoustic characteristics of ultrasonic coded transmitters for fishery applications: Could marine mammals hear them?
Authors: Bowles Ann E. , Denes Samuel L. , Shane Michael A.
Published: November 2010

Ultrasonic coded transmitters (UCTs) producing frequencies of 69–83 kHz are used increasingly to track fish and invertebrates in coastal and estuarine waters. To address concerns that they might be audible to marine mammals, acoustic properties of UCTs were measured off Mission Beach, San Diego, and at the U.S. Navy TRANSDEC facility. A regression model fitted to VEMCO UCT data yielded an estimated source level of 147 dB re 1 μPa SPL @ 1 m and spreading constant of 14.0. Based on TRANSDEC measurements, five VEMCO 69 kHz UCTs had source levels ranging from 146 to 149 dB re 1 μPa SPL @ 1 m. Five Sonotronics UCTs (69 kHz and 83 kHz) had source levels ranging from 129 to 137 dB re 1 μPa SPL @ 1 m. Transmitter directionality ranged from 3.9 to 18.2 dB. Based on propagation models and published data on marine mammal auditory psychophysics, harbor seals potentially could detect the VEMCO 69 kHz UCTs at ranges between 19 and >200 m, while odontocetes potentially could detect them at much greater ranges. California sea lions were not expected to detect any of the tested UCTs at useful ranges.
Perceptual contributions to monosyllabic word intelligibility: Segmental, lexical, and noise replacement factors
Authors: Fogerty Daniel , Humes Larry E.
Published: November 2010

This study investigated the relative contributions of consonants and vowels to the perceptual intelligibility of monosyllabic consonant-vowel-consonant (CVC) words. A noise replacement paradigm presented CVCs with only consonants or only vowels preserved. Results demonstrated no difference between overall word accuracy in these conditions; however, different error patterns were observed. A significant effect of lexical difficulty was demonstrated for both types of replacement, whereas the noise level used during replacement did not influence results. The contribution of consonant and vowel transitional information present at the consonant-vowel boundary was also explored. The proportion of speech presented, regardless of the segmental condition, overwhelmingly predicted performance. Comparisons were made with previous segment replacement results using sentences [Fogerty, and Kewley-Port (2009). J. Acoust. Soc. Am. 126, 847–857]. Results demonstrated that consonants contribute to intelligibility equally in both isolated CVC words and sentences. However, vowel contributions were mediated by context, with greater contributions to intelligibility in sentence contexts. Therefore, it appears that vowels in sentences carry unique speech cues that greatly facilitate intelligibility which are not informative and/or present during isolated word contexts. Consonants appear to provide speech cues that are equally available and informative during sentence and isolated word presentations.
Inverse problems in cancellous bone: Estimation of the ultrasonic properties of fast and slow waves using Bayesian probability theory
Authors: Anderson Christian C. , Bauer Adam Q. , Holland Mark R. , Pakula Michal , Laugier Pascal , Bretthorst G. Larry , Miller James G.
Published: November 2010

Quantitative ultrasonic characterization of cancellous bone can be complicated by artifacts introduced by analyzing acquired data consisting of two propagating waves (a fast wave and a slow wave) as if only one wave were present. Recovering the ultrasonic properties of overlapping fast and slow waves could therefore lead to enhancement of bone quality assessment. The current study uses Bayesian probability theory to estimate phase velocity and normalized broadband ultrasonic attenuation (nBUA) parameters in a model of fast and slow wave propagation. Calculations are carried out using Markov chain Monte Carlo with simulated annealing to approximate the marginal posterior probability densities for parameters in the model. The technique is applied to simulated data, to data acquired on two phantoms capable of generating two waves in acquired signals, and to data acquired on a human femur condyle specimen. The models are in good agreement with both the simulated and experimental data, and the values of the estimated ultrasonic parameters fall within expected ranges.
The effect of acoustically-induced cavitation on the permeance of a bullfrog urinary bladder
Authors: Cancelos Silvina , Moraga Francisco J. , Lahey Richard T. , Shain William , Parsons Robert H.
Published: November 2010

It is well known that ultrasound enhances drug delivery to tissues, although there is not a general consensus about the responsible mechanisms. However, it is known that the most important factor associated with ultrasonically-enhanced drug permeance through tissues is cavitation. Here we report results from research conducted using a experimental approach adapted from single bubble sonoluminescence experiments which generates very well defined acoustic fields and allows controlled activation and location of cavitation. The experimental design requires that a biological tissue be immersed inside a highly degassed liquid media to avoid random bubble nucleation. Therefore, live frog bladders were used as the living tissue due to their high resistance to hypoxia. Tissue membrane permeance was measured using radiolabeled urea. The results show that an increase in tissue permeance only occurs when cavitation is present near the tissue membrane. Moreover, confocal microscopy shows a direct correlation between permeance increases and physical damage to the tissue.
Subharmonic behavior of phospholipid-coated ultrasound contrast agent microbubbles
Authors: Sijl Jeroen , Dollet Benjamin , Overvelde Marlies , Garbin Valeria , Rozendal Timo , de Jong Nico , Lohse Detlef , Versluis Michel
Published: November 2010

Coated microbubbles, unlike tissue are able to scatter sound subharmonically. Therefore, the subharmonic behavior of coated microbubbles can be used to enhance the contrast in ultrasound contrast imaging. Theoretically, a threshold amplitude of the driving pressure can be calculated above which subharmonic oscillations of microbubbles are initiated. Interestingly, earlier experimental studies on coated microbubbles demonstrated that the threshold for these bubbles is much lower than predicted by the traditional linear viscoelastic shell models. This paper presents an experimental study on the subharmonic behavior of differently sized individual phospholipid coated microbubbles. The radial subharmonic response of the microbubbles was recorded with the Brandaris ultra high-speed camera as a function of both the amplitude and the frequency of the driving pulse. Threshold pressures for subharmonic generation as low as 5 kPa were found near a driving frequency equal to twice the resonance frequency of the bubble. An explanation for this low threshold pressure is provided by the shell buckling model proposed by Marmottant et al. [J. Acoust. Soc. Am. 118, 3499–3505 (2005)]. It is shown that the change in the elasticity of the bubble shell as a function of bubble radius as proposed in this model, enhances the subharmonic behavior of the microbubbles.
Influence of cancellous bone microstructure on two ultrasonic wave propagations in bovine femur: An in vitro study
Authors: Mizuno Katsunori , Somiya Hiroki , Kubo Tomohiro , Matsukawa Mami , Otani Takahiko , Tsujimoto Toshiyuki
Published: November 2010

The influence of cancellous bone microstructure on the ultrasonic wave propagation of fast and slow waves was experimentally investigated. Four spherical cancellous bone specimens extracted from two bovine femora were prepared for the estimation of acoustical and structural anisotropies of cancellous bone. In vitro measurements were performed using a PVDF transducer (excited by a single sinusoidal wave at 1 MHz) by rotating the spherical specimens. In addition, the mean intercept length (MIL) and bone volume fraction (BV/TV) were estimated by X-ray micro-computed tomography. Separation of the fast and slow waves was clearly observed in two specimens. The fast wave speed was strongly dependent on the wave propagation direction, with the maximum speed along the main trabecular direction. The fast wave speed increased with the MIL. The slow wave speed, however, was almost constant. The fast wave speeds were statistically higher, and their amplitudes were statistically lower in the case of wave separation than in that of wave overlap.
A dipole loudspeaker with a balanced directivity pattern
Authors: Mellow Tim , Kärkkäinen Leo
Published: November 2010

Analytical equations describing radiation characteristics of an oscillating ring in a circular finite baffle are derived, including the limiting case of a dipole point source at the center. An oscillating sphere would represent the ideal dipole source, having a constant directivity pattern at all frequencies, but would be inconvenient to realize especially in portable devices. It is found that a planar piston with uniform surface velocity but variable phase arranged to emulate the sphere does not have such a smooth on-axis response as the sphere. Instead a planar piston with the same phase distribution but uniform pressure represents an ideal planar source with a smooth on-axis response and near constant directivity. The surface velocity is plotted and it is then shown that a similar response can be achieved using a finite number of concentric rings based on this velocity distribution.
Localization of sound in rooms. V. Binaural coherence and human sensitivity to interaural time differences in noise
Authors: Rakerd Brad , Hartmann William M.
Published: November 2010

Binaural recordings of noise in rooms were used to determine the relationship between binaural coherence and the effectiveness of the interaural time difference (ITD) as a cue for human sound localization. Experiments showed a strong, monotonic relationship between the coherence and a listener’s ability to discriminate values of ITD. The relationship was found to be independent of other, widely varying acoustical properties of the rooms. However, the relationship varied dramatically with noise band center frequency. The ability to discriminate small ITD changes was greatest for a mid-frequency band. To achieve sensitivity comparable to mid-band, the binaural coherence had to be much larger at high frequency, where waveform ITD cues are imperceptible, and also at low frequency, where the binaural coherence in a room is necessarily large. Rivalry experiments with opposing interaural level differences (ILDs) found that the trading ratio between ITD and ILD increasingly favored the ILD as coherence decreased, suggesting that the perceptual weight of the ITD is decreased by increased reflections in rooms.
Human phoneme recognition depending on speech-intrinsic variability
Authors: Meyer Bernd T. , Jürgens Tim , Wesker Thorsten , Brand Thomas , Kollmeier Birger
Published: November 2010

The influence of different sources of speech-intrinisic variation (speaking rate, effort, style and dialect or accent) on human speech perception was investigated. In listening experiments with 16 listeners, confusions of consonant-vowel-consonant (CVC) and vowel-consonant-vowel (VCV) sounds in speech-weighted noise were analyzed. Experiments were based on the OLLO logatome speech database, which was designed for a man-machine comparison. It contains utterances spoken by 50 speakers from five dialect/accent regions and covers several intrinsic variations. By comparing results depending on intrinsic and extrinsic variations (i.e., different levels of masking noise), the degradation induced by variabilities can be expressed in terms of the SNR. The spectral level distance between the respective speech segment and the long-term spectrum of the masking noise was found to be a good predictor for recognition rates, while phoneme confusions were influenced by the distance to spectrally close phonemes. An analysis based on transmitted information of articulatory features showed that voicing and manner of articulation are comparatively robust cues in the presence of intrinsic variations, whereas the coding of place is more degraded. The database and detailed results have been made available for comparisons between human speech recognition (HSR) and automatic speech recognizers (ASR).
Covert underwater acoustic communications
Authors: Ling Jun , He Hao , Li Jian , Roberts William , Stoica Petre
Published: November 2010

Low probability of detection (LPD) communications are conducted at a low received signal-to-noise ratio (SNR) to deter eavesdroppers to sense the presence of the transmitted signal. Successful detection at intended receiver heavily relies on the processing gain achieved by employing the direct-sequence spread-spectrum (DSSS) technique. For scenarios that lack a sufficiently low SNR to maintain LPD, another metric, referred to as low probability of interception (LPI), is of interest to protect the privacy of the transmitted information. If covert communications take place in underwater acoustic (UWA) environments, then additional challenges are present. The time-varying nature of the UWA channel prevents the employment of a long spreading waveform. Furthermore, UWA environments are frequency-selective channels with long memory, which imposes challenges to the design of the spreading waveform. In this paper, a covert UWA communication system that adopts the DSSS technique and a coherent RAKE receiver is investigated. Emphasis is placed on the design of a spreading waveform that not only accounts for the transceiver structure and frequency-selective nature of the UWA channel, but also possesses a superior LPI. The proposed techniques are evaluated using both simulated and SPACE’08 in-water experimental data.
Volumetric diffusers: Pseudorandom cylinder arrays on a periodic lattice
Authors: Hughes Richard J. , Angus Jamie A. S. , Cox Trevor J. , Umnova Olga , Gehring Gillian A. , Pogson Mark , Whittaker David M.
Published: November 2010

Most conventional diffusers take the form of a surface based treatment, and as a result can only operate in hemispherical space. Placing a diffuser in the volume of a room might provide greater efficiency by allowing scattering into the whole space. A periodic cylinder array (or sonic crystal) produces periodicity lobes and uneven scattering. Introducing defects into an array, by removing or varying the size of some of the cylinders, can enhance their diffusing abilities. This paper applies number theoretic concepts to create cylinder arrays that have more even scattering. Predictions using a boundary element method are compared to measurements to verify the model, and suitable metrics are adopted to evaluate performance. Arrangements with good aperiodic autocorrelation properties tend to produce the best results. At low frequency power is controlled by object size and at high frequency diffusion is dominated by lattice spacing and structural similarity. Consequently the operational bandwidth is rather small. By using sparse arrays and varying cylinder sizes, a wider bandwidth can be achieved.
Influence of wall vibrations on the sound of brass wind instruments
Authors: Kausel Wilfried , Zietlow Daniel W. , Moore Thomas R.
Published: November 2010

The results of an experimental and theoretical investigation of the influence of wall vibrations on the sound of brass wind instruments are presented. Measurements of the transmission function and input impedance of a trumpet, with the bell both heavily damped and freely vibrating, are shown to be consistent with a theory that assumes that the internal pressure causes an oscillation of the diameter of the pipe enclosing the air column. These effects are shown to be most significant in sections where there are flaring walls, which explains why damping these vibrations in cylindrical pipes normally produces no measurable effects.
Ratings of speed in real music as a function of both original and manipulated beat tempo
Authors: Madison Guy , Paulin Johan
Published: November 2010

There is an apparent contradiction between the narrow range of tempi optimal for perceptual judgment and motor synchronization and the wide range of beat tempi found in real music. The relation between listeners’ perception of speed and beat tempo was therefore investigated, both for real music excerpts (ME) and metronome sequences. Tempi ranged from 42 to 200 beats per minute (BPM), and some excerpts were further tempo manipulated in four levels from ±5 to ±20%. Regression analyses showed that speed was a shallower function of original tempo for fast (>150 BPM) and slow (<95 BPM) MEs than for MEs with intermediate tempi, describing a non-linear, sigmoid function. Manipulated tempo had twice as large an effect on speed as had original tempo. In contrast, speed was an almost linear function of tempo for metronome sequences. Taken together, these results show that the non-linearity stems from properties of the musical signal, rather than being a subjective perceptual effect. They indicate an inverse relation between tempo and relative event density in real music, and demonstrate that the perception of periodic signals is affected not only by the beat level, but also by faster and slower levels.
Within-channel cues to comodulation masking release for single and symmetrically placed pairs of flanking bands
Authors: Goldman Simon A. , Baer Thomas , Moore Brian C. J.
Published: November 2010

Comodulation masking release (CMR) as measured in a flanking-band (FB) paradigm is often larger when the FBs are close to the signal frequency, fs, than when they are remote from fs, an effect which may be partly due to the use of within-channel cues. Schooneveldt and Moore [J. Acoust. Soc. Am. 85, 262–272 (1989)] reported that, for fs=1000 Hz, this effect was larger when a single FB was used than when there were two FBs symmetrically placed about fs, and proposed that there are within-channel cues that are available for a single FB, but not for a symmetrically placed pair of FBs. The present study replicated and extended their study. Although CMR was larger for two symmetrically placed FBs than for a single FB, the effect of FB proximity to fs did not differ for the two cases. The results do not support the idea that there are additional within-channel cues that are available for a single FB. Changes in the regularity of temporal fine structure and changes in the prevalence of low-amplitude envelope portions are both plausible within-channel cues.
Effect of granular media on the vibrational response of a resonant structure: Theory and experiment
Authors: Valenza John J. , Hsu Chaur-Jian , Johnson David Linton
Published: November 2010

The acoustic response of a structure that contains a cavity filled with a loose granular material is analyzed. The inputs to the theory are the effective masses of each subsystem: that of the empty-cavity resonating structure and that of the granular medium within the cavity. This theory accurately predicts the frequencies, widths, and relative amplitudes of the various flexural mode resonances observed with rectangular bars, each having a cavity filled with loose tungsten granules. Inasmuch as the dominant mechanism for damping is due to adsorbed water at the grain-grain contacts, the significant effects of humidity on both the effective mass of the granular medium as well as on the response of the grain-loaded bars are monitored. Here, depending upon the humidity and the preparation protocol, it is possible to observe one, two, or three distinct resonances in a wide frequency range (1–5 kHz) over which the empty bar has but one resonance. These effects are understood in terms of the theoretical framework, which may simplify in terms of perturbation theories.
Objective detection and quantification of mucosal wave propagation
Authors: Voigt Daniel , Döllinger Michael , Eysholdt Ulrich , Yang Anxiong , Gürlek Ercan , Lohscheller Jörg
Published: November 2010

In this work a detection algorithm for mucosal wave propagation is presented. By incorporating physiological knowledge of mucosal wave properties and taking the segmented lateral movement of both vocal fold edges as a basis, the spatio-temporal position of the traveling mucosal wave is identified and quantitatively captured. The course of mucosal wave propagation can be successfully detected and analyzed with regard to discriminating different types of mucosal wave activity (in terms of spread velocity and symmetry). The preliminary results obtained for six exemplary laryngeal high-speed recordings are promising and demonstrate the potential of the proposed detection and objective description approach.