bluuebunny/crossref_metadata_2025 huggingface dataset:
The parametric array in Berea sandstone: definitive experiments.
Authors: Bas Pierre-Yves Le , TenCate James A. , Guyer Robert A. , Johnson Paul A.
Published: October 2013

Previous measurements of the characteristics of the parametric array in sandstone by Johnson and Shankland [J. Geophys. Res. 94, 17729–17734 (1989)] were difficult to perform and only qualitative. Scanning laser vibrometers (Polytec) now make parametric array measurements in rock easier. However, hysteresis and memory effects play a strong role in the dynamic behavior of rocks and have the potential to mess up the creation of the parametric array in the medium. Thus, an experimental study was performed to find out just how well the “classical” theory of nonlinear acoustics works for a granular solid, a sandstone. An array of alternating PZT disk transducers was epoxied to a large block of Berea sandstone (1.2, 0.4, 0.4 m), every other one broadcasting with separate frequency generators and amps. Primary frequencies were around 100 kHz; difference frequencies of 10 to 20 kHz were observed. Two-D beampattern scans were taken and the results compared with calculations based on classical theory. The agreement is surprisingly good with a beta of around 200 and a Q (inverse attenuation) of 50.
Precedence effect in children and adults: Effects of heard and unheard echoes on localization accuracy.
Authors: Litovsky Ruth , Godar Shelly , Wesolek Phillip
Published: October 2013

The precedence effect is thought to facilitate sound localization in reverberant environments through localization dominance. This is demonstrated at short lead-lag delays, when a single fused auditory image is heard whose perceived location is dominated by the leading source. We studied localization dominance in children ages 4–5 and in adults. Stimuli were brief noise bursts, with lead-lag delays ranging from 1–100 ms; the lead location varied along the azimuth (−60, −40, −20, 20, 40, 60 deg) and the lag was fixed at 0 deg. Subjects indicated the perceived location(s) of each heard source. Localization accuracy was computed for the lead and lag at each delay. On a separate task, with delays varying randomly, subjects indicated whether they heard one or two auditory events, and echo threshold was obtained. Results show that localization accuracy for the lead declined as delays increased, suggesting that as the lag became more audible its interference in the localization process increased. For most subjects, the interference was predictable from independent measures of fusion echo thresholds. The impact of the lag, a single simulated echo, on localization accuracy, was greater for children than adults. These data suggest that the precedence effect is less effective at facilitating sound localization in young children than in adults. [Work supported by NIDCD Grant R01DC008957.]
Azimuth dependency in auditory perception of speaker’s facing angle.
Authors: Kato Hiroaki , Takemoto Hironori , Nishimura Ryouichi , Mokhtari Parham
Published: October 2013

In pursuit of an ultimately realistic human-to-human telecommunication technology, the ability to auditorily perceive the facing direction of a human speaker was measured. A male speaker sat on a pivot chair in an anechoic chamber and spoke a short sentence (about 5 s) while facing either of eight azimuth angles (0=listener’s direction, 45, 90, 135, 180, 225, 270, or 315 deg). These angles were set solely by turning the pivot chair. Blindfolded listeners heard the spoken sentence at a distance of either 1.2 or 2.4 m from the speaker and were asked to indicate the speaker’s facing angle. The average of errors between listeners’ responses and actual speaker’s facing angles was 23.5 deg. Further analyses showed a significant effect of the speaker’s facing azimuth on the accuracy of listeners’ responses. Listeners made remarkably small errors (6.6 deg on average) when the speaker faced the listener’s direction (azimuth = 0 deg). The second smallest errors were observed for the back angle (azimuth = 180 deg). Few front-back confusions were observed. This dependency of listeners’ accuracy was extensively discussed from the interest of effective acoustic cues obtained by a precise computer simulation as well as an ecological perspective.
Dynamic modeling of complex structures in a broad frequency range.
Authors: Xu Hongan , Li Wen L.
Published: October 2013

A general method, the so-called finite substructurE method (FSEM), is presented for the dynamic analysis of complex structural systems. In this method, a complex structure is considered as a collection of a finite number of basic structural components such as beams, plates, and shells. Instead of seeking a numerical solution at a number of discrete or grid points, the current displacement solution is sought, over each component, as a continuous field in the form of Fourier series expansions. Thus, the number of degrees of freedom, which now represent the Fourier expansion coefficients, can be substantially reduced in comparison with a grid-based solution for the same spatial resolution. Mathematically, the resulting system tends to be better conditioned than those in the finite element methods as the number of DOF’s increases with frequency. The robustness of this model for high frequency applications can be further improved by incorporating statistical processes into the modeling method to properly reflect the means or account for the uncertainties of certain input variables. The proposed substructure method is considerably different from the existing substructure techniques in that no modal data are required for any component. Numerical examples are presented to demonstrate the reliability of this method.
Formant-frequency trajectories as acoustic correlates to speech perception.
Authors: Kiefte Michael , Collins Tara , Stilp Christian , Kluender Keith R.
Published: October 2013

Formant trajectories are excellent vowel discriminants; within vowel, they are nearly constant across speaker size, age, and sex, and across consonantal contexts. However, this model assumes that formant peaks are perceptually important and that human listeners track formant-frequency changes across time. Speech-recognition applications have avoided formant frequencies due to the difficulty of reliable formant tracking. In addition, it is not actually known whether human listeners do indeed follow formants perceptually across time. This paper presents results from several studies that examine the relationship between changing formant frequencies and perception. Alternative perceptual representations of vowels, such as global spectral shape, are precluded by evidence that individual formant amplitudes are largely ignored in vowel perception. In addition, where other spectral properties appear to have a perceptual effect, it is because stimuli have used formants that do not change. When formants are changing, perceptual effects of spectral shape properties disappear. In terms of human formant tracking, perceptual extrapolation of a formant sweep is mostly dependent on peak frequency and not other properties related to spectral shape. This demonstrates that listeners do indeed follow formant-frequency changes as auditory objects. Further research on formant frequency perception will be described.
Generational and dialectal effects on children’s vowel identification.
Authors: Jacewicz Ewa , Fox Robert Allen
Published: October 2013

This study examines vowel identification by 8–13 years old children who grew up in either Southeastern Wisconsin (whose regional variant is affected by the Northern Cities Shift) or Western North Carolina (affected by the Southern Vowel Shift). In the first identification task, the children responded to words edited from sentences which elicited both stressed and unstressed vowel exemplars. This speech material was produced by multiple talkers representing two generations (children and older adults who represent their grandparents’ generation). In the second identification task, the children were presented with citation-form tokens produced by three generations of talkers (children, their possible parents, and their possible greatgrandparents). Both within- and across-dialect vowel identification was examined. The cross-generational results showed that some vowels were identified more accurately when spoken by children, some when spoken by adults and for others there were no cross-generational differences. The cross-dialectal results indicated generally more accurate identifications of vowels produced by talkers from the same dialect region as the listeners. For selected vowels, there were significant interactions between dialect and generation. As a whole, the study shows children’s sensitivity to cross-generational vowel changes and the attunement to their own dialect. [Work supported by NIH.]
Vowel detection and vowel identification in long-term speech-shaped noise.
Authors: O’Brien Kathleen , Woodall Ashley , Liu Chang
Published: October 2013

Psychometric functions of vowel detection and vowel identification were measured in long-term speech-shaped noise (LTSSN) for normal-hearing listeners. A four-interval forced-choice procedure was used to examine the accuracy of vowel detection in LTSSN with speech level presented from −10 to +5 dB sensational level relative to vowel detection thresholds obtained from Liu and Eddins’ study [J. Acoust. Soc. Am. 123, 4539–4546 (2008)]. The accuracy of vowel detection was significantly influenced by vowel category and sensational level. The threshold of vowel detection for each vowel and each listener was defined as the speech level at which 70.7% accuracy of vowel detection was reached. Vowel identification was then measured in LTSSN with vowel levels presented from 0 to 12 dB sensational level relative to individual thresholds of vowel detection, using a close-set 12-choice procedure. Results suggest that vowel identification was significantly affected by vowel category and sensational level. Altogether, the results of vowel detection and vowel identification indicate that, given the same signal-to-noise ratio, vowels are not equally audible and identifiable. Moreover, given the same sensational levels, vowels do not have the same identifiability, possibly due to the fact that some vowels have dominant confusing vowels while others do not.
Voice identification accuracy using multivariate vowel formant analysis.
Authors: Yonovitz Al , Moss Elvan
Published: October 2013

Accurate and automated voice or speaker identification has been a major goal for those involved in forensic issues. In addition, voice and speaker identification has many applications in security and business. Numerous previous efforts to derive features for speaker classification have failed to achieve a sufficiently low error rate. In this study a linear discriminant analysis was independently performed for vowel formants (F1, F2, F3) for each of ten vowels. The standardized canonical discriminant coefficients (SCDC) weighted each of the formants within a database of voices. These SCDC values were then linearly combined to form a single scalar for each vowel. An analysis that considered the multivariate data vector composed of the ten vowel scalars was then used for classification. This algorithm was tested by comparing single voice exemplars to other voices in the database. Accuracy was extremely high using vowel formant values for classification.
Acoustic vowel space in pre-/r/ contexts: Shetland and American English.
Authors: Sundkvist Peter
Published: October 2013

The acoustic space available to vowel systems in pre-/r/ contexts commonly differs from that of other phonetic contexts. In English this space has gradually shrunk, which relates to changes in the phonetic nature of /r/, having gone from more consonantal articulations (tap, trill) to approximant and often complex articulations that have a stronger effect on the production and perception of adjacent vowels (e.g., “bunched” and retroflex /r/). This paper contains an acoustic study of pre-/r/ vowel systems in Shetland and American English. F1–F3 values were obtained from steady state vowel portions from words spoken in isolation. The acoustic vowel spaces and the positions of contrastive items within these are compared and discussed in relation to the phonetic nature of /r/ and its effects on vowel formants. In contrast to American English, Shetland maintains a trill or tap as the principal realization of /r/, and the full range of vowel contrasts found elsewhere is supported before /r/. As Shetland is one of the most conservative English dialects in this respect, the study may also offer some insight into the acoustic characteristics of English pre-/r/ vowel systems of earlier periods and the pressures affecting such systems.
Joint position/wave number and time/frequency features of signals.
Authors: Cohen Leon , Loughlin Patrick
Published: October 2013

Joint position/wave number and time/frequency representations of nonstationary signals and noise yield features that may be used to classify signals. Among these are instantaneous frequency, group delay, instantaneous bandwidth, and other conditional, or local, moments. We present a review of these concepts and give examples from various fields. We also discuss how these features change when a pulse propagates through a dispersive medium and show that there are some moment features that are invariant to dispersion. We illustrate via simulation the utility of these dispersion-invariant features for classification of man-made objects (steel shells) in shallow water environments. Finally, we show how to transform equations of motion into phase space, and the advantages of this transformation, in terms of methods of approximation and characterization of signals and nonstationary noise. [Work supported by ONR.]
Interpreting free-field scattering by metallic truncated cylinders and spherical shells.
Authors: Marston Philip L. , Baik Kyungmin
Published: October 2013

When investigating the complications to the scattering caused by proximity of a target to a boundary, a detailed ray-based interpretation of free-field scattering is often helpful. For tilted metallic cylinders having flat ends, when ka exceeds about 10, strong contributions to the backscattering have been identified with the radiation of sound by guided elastic waves associated with meridional rays, helical rays, and face-crossing rays [K. Gipson and P. L. Marston, J. Acoust. Soc. Am. 107, 112–117 (2000)]. These features also affect the frequency response as a function of tilt and bistatic synthetic aperture sonar (SAS) and acoustic holographic images [K. Baik, Ph.D. thesis, WSU, 2008]. When considering the response of shells to transient insonification, it can also be helpful to construct the time-frequency response and to interpret the response using ray-based methods [D. H. Hughes, Ph.D. thesis, WSU, 1992; S. F. Morse and P. L. Marston, J. Acoust. Soc. Am. 111, 1289–1294 (2002)]. Correct interpretation of the time-frequency response requires detailed consideration of the dispersion and attenuation of elastic waves guided by the shell and the shape of the radiated wavefronts. When considering low-frequency scattering, the inertia of the target significantly influences the scattering. [Work supported by ONR.]
Effect of shallow water variability on the waveguide invariant distribution.
Authors: Rouseff Daniel , Petnikov Valery
Published: October 2013

When mapped versus range and frequency, acoustic intensity often displays a regular pattern of striations, ribbons of high intensity. The trajectory of these striations may be described by the waveguide invariant, commonly designated as beta. While beta may be formally an invariant quantity, it is not necessarily a constant, particularly in highly variable shallow water environments. To study fluctuations in beta due to fluctuations in the environment, it is useful to generalize from an invariant scalar to the waveguide invariant distribution. Through data analysis and simulation, the waveguide invariant distribution is calculated for different locations including the New Jersey shelf off the United States and the Kamchatka shelf off Russia. The effects of isotropic and anisotropic internal waves are quantified. [Work supported by ONR and the Russian Foundation for Basic Research.]
Waveguide invariant motion compensation for adaptive beamforming.
Authors: Yang T.C. , Turgut Altan
Published: October 2013

Performance of high-resolution adaptive beamformers is significantly degraded when moving sources and interferers are considered. For a source changing bearing, the motion effect can be compensated by integrating over beam covariant matrix. For a source changing range, the motion effect can be compensated by a frequency change using waveguide invariant theory [T. C. Yang, J. Acoust. Soc. Am. 113(1), 245–260 (2003)]. Simulated data showed that the signal beam of a moving source is narrow as for a stationary case when motion compensation is applied. Also, interference power has been suppressed by 6–10 dB when the motion of the interferer does not match that of the source. Motion compensation algorithms were also applied to ship noise data from the passing merchant ships, collected on a bottomed horizontal array during the RAGS 2003 experiment at the New Jersey Shelf. Similar results are obtained indicating narrower beamwidths and selective suppression of signals from the passing merchant ships when proper motion compensation is considered. [Work supported by ONR.]
Evaluation of mechanical background noise outside the norm of generally accepted criteria.
Authors: Boone Andrew J. , Yantis Michael R.
Published: October 2013

Cases are presented where mechanical background noise was found to be acceptable by clients, although it was above the threshold of conventional indoor noise criterion. Other instances are shown where noise levels fell within normal limits but were judged unacceptable. Examples include HVAC noise in offices and residences, chiller and other rooftop equipment noise in multifamily dwellings, and pump noise. Sound quality expectations and the perception of noise sources were found to play an important role in the evaluation of these noise sources.
Acoustical criteria in a two-parameter system for evaluating impact noise insulation.
Authors: LoVerde John , Dong Wayland
Published: October 2013

Experience indicates that impact noise complaints in multi-family joist-framed buildings fall into two broad classes: low frequency thudding from footfalls and mid- to high frequency noise from heel clicks, dragging furniture, etc. The authors have developed a two-parameter system for evaluating impact noise [LoVerde and Dong, J. Acoust. Soc. Am. 119, 3220 (2006); 120, 3206 (2006); 122, 2954 (2007)] that offers considerable improvement over existing metrics (such as FIIC) in terms of both correlation with subjective reaction and comparison of materials intended for improving impact insulation. Based on this system, suggested criteria for impact noise levels are presented. The effects of various design parameters on noise levels are discussed.
The hyena’s laugh as a multi-informative signal.
Authors: Mathevon Nicolas , Koralek Aaron , Glickman Steve , Theunissen Frederic
Published: October 2013

Many social mammals use vocalizations to encode information about sex, kinship, individual identity, and morphological cues, as well as motivational and physiological states. In spite of the importance of this multi-informative signaling for the maintenance of social groups, most investigations on information coding in vocal signals have focused on only one cue; e.g., individual identity. Using the opportunity of the captive colony of spotted hyenas Crocuta crocuta at the Field Station for the Study of Behavior, Ecology, and Reproduction (University of California, Berkeley), we recorded and analysed the hyena’s giggle, one of the most well known calls of this large social African mammal. The acoustic analysis in both temporal and frequency domains was automated using a MATLAB customized routine. The fundamental frequency was tracked using two methods (cepstrum and autocorrelation) followed by a best guess using a Bayesian approach. The differences between giggles from different individuals or groups of individuals were assessed running a multiple analysis of variance (MANOVA in MATLAB), cross-validated by a permuted discriminant function analysis (pDFA, R software). The results show that the hyena’s laugh encodes information about age, dominance status, and individual identity, giving to receivers some cues to assess the social position of an emitting individual.
An intelligent automated apparatus to assess absolute auditory thresholds in the laboratory mouse.
Authors: Pleuger Anna , Yonovitz Al
Published: October 2013

The effectiveness of an intelligent behavioral training and testing apparatus was assessed by using this system to operantly condition mice. The method utilized an infrared grid that determined the location of the mouse and presented reinforcements for auditorily contingent bar-press behavior. The apparatus was fully automated. Absolute auditory thresholds were determined with the descending and ascending method of limits in the same group of C57BL/6 mice. There was a statistically significant difference between thresholds produced by these two methods, with the descending method producing more sensitive auditory thresholds. Thresholds were on average 4.4 dB lower and had smaller standard errors. Overall, the automated apparatus was a highly efficient and precise method for the operant conditioning of mice.
A predictive model using myocardial contrast echocardiography for patients presenting to the emergency department with chest pain and a nondiagnostic electrocardiogram.
Authors: Kaul Sanjiv
Published: October 2013

Risk stratification of patients presenting to an emergency department (ED) with suspected cardiac chest pain (CP) and an undifferentiated electrocardiogram (ECG) is difficult. We hypothesized that a risk score incorporating clinical, ECG, Rand contrast echocardiography variables [regional function (RF) and myocardial perfusion (MP)] obtained at the bedside would accurately predict adverse events in occurring within 48 h of ED presentation. A logistic risk model was developed in the initial 1166 patients (cohort 1), and validated in another 720 patients (cohort 2). Any abnormality or ST-T changes on ECG (OR 2.5, 95% CI:1.4–4.5, p=0.002, and OR 2.9, 95% CI:1.7–4.8, p=0.001, respectively), abnormal RF with normal MP (OR 3.5, 95% CI:1.8–6.5, p=0.001), and abnormal RF with abnormal MP (OR 9.6, 95% CI:5.8–16.0, p=0.001) were found to be significant multivariate predictors of nonfatal myocardial infarction or cardiac death. The estimate of the probability of concordance for the risk model was 0.82 for cohort 1. Likewise, in cohort 2, the c-index for the risk model was 0.83. In conclusion, a model based on variables obtained at the patient’s bedside can be used to accurately risk stratify patients presenting to the ED with suspected cardiac CP and a nondiagnostic ECG. Its application could enhance care of CP patients in the ED.
120 kilohertz ultrasound-enhanced thrombolysis in a porcine intracerebral hemorrhage model.
Authors: Ammi Azzdine Y. , Datta Saurabh , Perrin Stephen R. , Beiler Shauna L. , Beiler Christian R. , Wagner Kenneth R. , Holland Christy K.
Published: October 2013

Ultrasound acts synergistically with thrombolytic agents, such as recombinant tissue plasminogen activator (rt-PA), to accelerate thrombolysis. The aim of the study was to demonstrate the efficacy of 120-kHz ultrasound-enhanced rt-PA thrombolysis in a porcine hemorrhagic stroke model in vivo. Clots were formed by infusing 3 ml of autologous blood into the frontal white matter of 30 mixed-bred Yorkshire pigs (20.5–3.1 kg) and incubated for 3 h. For these nonsurvival studies, six pigs received rt-PA alone (0.3 cc of 0.107 mg/ml), six received ultrasound alone, six received rt-PA plus ultrasound, six were sham-exposed (saline only), and six were controls (no ultrasound or rt-PA treatment). The clots receiving ultrasound treatment were insonified with a peak-to-peak pressure of 0.48 MPa in situ (80% duty cycle, and PRF of 1.7 kHz) for 30 min. Clots treated with rt-PA alone exhibited a volume loss of 55.0% and clots treated with rt-PA and 120-kHz ultrasound had a significantly higher volume loss of 75.2% and a higher penetration of rt-PA. Thus, 120-kHz pulsed ultrasound enhancement of thrombolysis has been demonstrated both in vitro and in an in vivo porcine hemorrhagic stroke model.
High-frequency imaging with targeted ultrasound contrast agents under vascular flow conditions.
Authors: Anastasiadis Pavlos , Allen John S.
Published: October 2013

Targeted ultrasound contrast agents (UCA) were conjugated with biotinylated ligands, which allow them to adhere to specific diseased sites of interest. The overall adhesion of contrast agents is influenced by both the flow mediated gene expression and the local hydrodynamic forces acting on the contrast agents’ trajectories. The ability to bind under pulsatile flow conditions and scatter sound at high frequencies is important for potential applications involving intravascular ultrasound. Human aortic endothelial cells (HAECs) in a flow chamber were exposed to a steady shear pretreatment over 12 h using a peristaltic pump system and subsequent pulsatile waveforms. To stimulate an inflammatory reaction in the HAECs, cells were subsequently exposed to rhTNF945; (Roche Pharmaceuticals). Different flow rates were applied, and the binding efficacy of targeted UCA was evaluated. Real-time transendothelial electrical impedance measurements and simultaneous acoustic measurements were performed on the same specimen with a scanning acoustic microscope. Applications related to targeting plaque in blood vessels are discussed. [This work was supported by the National Institutes of Health Grants NIH 2 P20 RR016453-05A1 and NIH 2 G12 RR0030161-21.]
Soundscape approach in progress—Report on the current stage.
Authors: Schulte-Fortkamp Brigitte
Published: October 2013

Soundscapes have become an important issue in environmental acoustics. Following Soundscape workshops in Vancouver, Salt Lake City, and Miami, a Soundscape Symposium took place in Berlin, Germany, and brought together expertise from all over the world to work on concepts, approaches, analyses, applications, as well as source- and pattern recognition with respect to Soundscapes. Therefore, acousticians, architects, city planners, engineers, psychologists, sociologists, and the people concerned were invited. The aim of the workshop was to define Soundscapes for future work. Moreover, concepts, approaches, analyses, and applications were related to the categorization of Soundscapes as urban, cultural, and wilderness, also focussing on source and pattern recognition. This paper will report on the results to outline the next steps towards standardization.
Integrating soundscape analysis into the National Environmental Policy Act process: A case study.
Authors: Luz George
Published: October 2013

A challenge for the proponents of soundscape analysis within the U.S. is how to integrate subjective observations with the quantitative requirements of the National Environmental Policy Act (NEPA), which, historically, emphasize physical measurements of all pollutants, including sound pollution. This paper describes a case study in which an attempt is made to integrate the subjective impressions of a soundscape analysis with objective measurements of equivalent sound level (LEQ). The occasion for this effort was a Base Realignment and Closure (BRAC) action in which the proposed reuse for a former military installation is park and recreational use. The quantitative framework for this study was a graphic used by the U.S. Army Environmental Hygiene Agency (USAEHA) during the 1980s in which the 24 h pattern of outdoor noise exposure is displayed as the minimum, average, and maximum values of 10 min LEQ over the course of a week of measurements. Although the intent of the USAEHA approach had been to determine conformance of military residential areas to Army guidelines, their method for displaying measurement data proved to be amenable to soundscape analysis as well.
Forward-masking functions in listeners with real and simulated hearing loss.
Authors: Braida Louis D. , Desloge Joseph G. , Reed Charlotte M. , Delhorne Lorraine A. , Perez Zachary D.
Published: October 2013

Forward-masking functions were obtained in eight listeners with moderate to severe sensorineural hearing loss (aged 21–69 years). The hearing loss of each impaired listener was simulated in a group of three age-matched normal-hearing listeners through a combination of spectrally shaped masking noise and multiband expansion. Forward masking was measured in both groups of listeners for probe signals at frequencies of 500, 1000, 2000, and 4000 Hz using an on-frequency masker and two off-frequency maskers (0.55 and 1.15 times the signal frequency) under a 3I, 2AFC procedure. The probe signal was presented at 5 dB SL; signals and maskers were gated with 5-m on/off times with a steady-state duration of 0 ms for probe signals and 100 ms for maskers; and values of masker-offset time to signal-onset time were in the range of 0 to 100 ms. Findings will be described in terms of the slopes of the masking functions for each combination of probe and masker frequency and the ratio of the slopes obtained with on- relative to off-frequency maskers. Preliminary results suggest that the slope ratios observed for the hearing-impaired listeners were generally well-reproduced in normal-hearing listeners with simulated hearing loss. [Work supported by NIH-NIDCD R01 DC00117.]
Quality judgments for music signals by normal-hearing and hearing-impaired listeners.
Authors: Arehart Kathryn H. , Kates James M. , Anderson Melinda C.
Published: October 2013

Noise, distortion, nonlinear signal-processing algorithms, and linear filtering can all affect the sound quality of a hearing aid or other audio device. Most hearing-aid research concentrates on speech, but music reproduction can also be an important factor in user satisfaction. In this presentation, quality judgments are made for several different music signals by normal-hearing and hearing-impaired listeners. The music signals include orchestral classical music, jazz instrumental, and vocal. The signal processing uses a simulated hearing aid. The noise and nonlinear signal degradations include additive noise, multitalker babble, peak-clipping distortion, quantization noise, multichannel compression, spectral subtraction. Linear filtering conditions include bandwidth limitation, spectral resonance peaks, and spectral tilt. Conditions combining noise and nonlinear processing with linear filtering are also included. Subject ratings of the degraded music will be presented, along with comparisons of the ratings of music with that of speech for the same set of processing conditions. In addition, the subject ratings will be compared predictions using quality metrics based on auditory models.
Preference and performance for hearing-aid gain-compression prescriptions, based on a preliminary model of impaired sensitivity to tone intensity.
Authors: Goldstein Julius L. , Valente Michael , Oz Metin , Gilchrist Peter
Published: October 2013

A cochlearlike preliminary model was synthesized by joining a model of loss of cochlear “tip” gain, representing mild hearing loss, with a model for greater loss that translates the residual range for tone intensities into nonlinear “tail” expansion. Normal tip gain was modeled as 40 dB with square-root compression. Tail expansion was modeled with upper bounds for residual hearing at normal LDL of 100 dB HL, or at levels increasing by half decibel per decibel hearing loss above 40 dB; the latter provides less compression. A digital hearing aid comprising six octave-bandwidth (0.25–8 kHz) linear amplifiers with AGC was simulated to test alternative prescriptions with 32 experienced users of hearing aids. Preference for prescriptions with high or low compression and 4 or 8 kHz bandwidth was tested with clean speech repeated at input levels of 40, 60, and 80 dB SPL. The alternative best perceived as “mild,” “comfortable,” and “loud” was chosen; if uncertain, “either” was chosen. Performance was measured with intelligibility scores for low-probability speech sentences in noise (SPIN) at 8 dB signal to noise ratio and 70 dB SPL input. Independent of preference, high-compression prescriptions provided inferior performance, resulting from excessive increase in compression with hearing loss. [Work supported by NIDCD.]
Effects of aging and irrelevant-dimension fluctuation on frequency doscrimination: Interference at late information-processing stages.
Authors: Jajoria Praveen , Espinoza-Varas Blas
Published: October 2013

Deficits in the ability to extricate relevant from irrelevant information at the perceptual level (i.e., selective attention) could help diagnose age-related cognitive decline at an early stage. Much experimental evidence supports this generalization, but there is debate as to where and how the irrelevant information interferes with the relevant one. To address this question, effects of irrelevant duration or level differences on pure-tone frequency discrimination thresholds (FDTs) were studied in healthy, normal-hearing, young and older adults. Target tones were presented either in isolation or followed by a distracter tone after a 90- or 350-ms silent interval; both tones were 1000 Hz, 80 ms, and 70 dB SPL. Irrelevant differences occurred simultaneously with relevant frequency differences or sequentially, in the distracter. With both presentation formats and silent intervals, FDT elevations (i.e., interference) were much larger in older than in young adults if the irrelevant differences were in level, but if they were in duration, FDT elevations were small in both groups. Since it occurs both simultaneously and retroactively (i.e., sequential), and depends on the similarity of relevant and irrelevant dimensions, the interference seems to take place at relatively late rather than early information-processing stages.
Perceptually important acoustic features of environmental sounds.
Authors: Heller Laurie M. , Skerritt Benjamin , Ammerman Emily
Published: October 2013

Listeners were asked to indicate the sources of dozens of sound events presented over headphones. The sounds were environmental sounds made by solid objects, liquids, and/or air undergoing a variety of actions taken from the website www.auditorylab.org. Each listener gave a series of responses about possible sources for each sound so that a similarity matrix could be constructed. The results of data reduction point to a manageable set of perceptual classes of sound events that can be described with a small number of distinctive spectro-temporal acoustic features. These features will be related to the attributes of the events that generated each class of sounds. Results for normal-hearing listeners will be analyzed in detail and preliminary results from hearing-impaired listeners will be previewed. [Work supported by NSF 0446955 and RI STAC.]
The incongruency advantage in elderly versus young normal-hearing listeners.
Authors: Gygi Brian , Shafiro Valeriy
Published: October 2013

Previous research [Gygi & Shafiro (2007); Leech et al. (2007)] reported that environmental sounds heard in contextually incongruous naturalistic auditory scenes are better identified than sounds contextually congruous with the scene (e.g., rooster crowing in a farm ambience versus rooster in an office ambience). This incongruency advantage (IA) averages about four-to-five percentage points in p(c) and has been observed in both well-trained and naïve young normal hearing listeners [Gygi and Shafiro (2008)] and in children [Leech et al. (2007)]. One aspect of the IA is that it appears to be level-dependent, in that the effect is not present for lower sound/scene ratios (So/Sc). For experienced young listeners, the IA appears at a So/Sc of −15 dB. However, for naive young listeners, it is not manifest until −7.5 dB. A group of elderly normal-hearing listeners were tested and exhibited an IA only at So/Sc of −9 dB and above. The results show that the incongruency advantage are complex effects resulting from a combination of peripheral and central factors. [Research supported by the Merit Review Training Grant from the Dept. of Veterans Affairs Research Service, VA File # 06-12-00446, the National Institute for Aging, and the Rush Univ. Medical Center.]
Synchronization of mechanical phase oscillators.
Authors: Mertens David , Weaver Richard , Koliniski John
Published: October 2013

The Kuramoto model of a large number of weakly interacting phase oscillators exhibits a phase transition to synchronization. The literature has seen analytic theory and numerical simulations for both the Kuramoto model and sundry generalizations. Most real-world systems (e.g., flashing fireflies) imperfectly match the model, and their synchronization behaviors can therefore be taken to be in merely qualitative support of the theory. Here a mechanical system with well-understood microphysics is presented. A number N (of order 50) of eccentrically weighted DC motors (cell phone vibrators) is mounted on a plate. Each motor radiates into the plate and responds to its motion. If the plate dynamics is dominated by a single normal vibration mode the system is well described by finite-N Kuramoto equations. Transitions to synchronization are observed in accord with theoretical expectations based on the quality factor of the plate, the number of motors, the ratio of the motor mass to the plate mass, and the natural speed of the motors. Calculations and results on a rich generalized-Kuramoto model are also presented, in which the plate dynamics entails many normal modes of vibration, and for which the governing equations resemble those of a laser.
On vibroacoustic modal analysis of arbitrarily shaped vibrating structures.
Authors: Lu Huancai , Wu Sean
Published: October 2013

Vibroacoustic modal analysis based on Helmholtz least squares method (HELS) is presented in this paper to explore the inherent dynamic characteristics and correlation of structural vibration and sound radiation of arbitrarily shaped vibrating structures. A series of mutually orthogonal vibroacoustic components is established by decomposing the normal velocity and normal acoustic intensity, which are reconstructed on source surface using HELS, in an orthogonal space through singular value decomposition (SVD). By further analyzing the vibration efficiency and radiation efficiency, the contribution of each of individual modal components to the resultant structural vibration and sound radiation can then be quantified. Therefore one is allowed to identify the vibroacoustic modal components that are most responsible for resultant structural vibration and sound radiation. The test object is a clamped and baffled thin rectangular steel plate, which was excited by a shaker and tested in a semianechoic chamber. The reconstructed normal surface velocities of the plate are validated against the results scanned by laser equipment. The vibration efficiency and radiation efficiency of the vibroacoustic modal components are examined, and the correlation between structural vibration and sound radiation of components at several frequencies is analyzed.
Visualization of vibrations measured with a multi-channel optical vibration sensor.
Authors: Hasegawa Jun , Kobayashi Kenji
Published: October 2013

Displacement-type sensor units made of optical fibers were developed to realize multi-points measurement of vibrations with high spatial resolution. Each sensor unit has the displacement resolution of 10 nm within the dynamic range of more than 90 dB, the frequency bandwidth of up to 80 kHz. Up to 64 sensor units can be arrayed as a multi-channel sensor head, with the minimum gap between sensor units of 4 mm. It means that the spatial resolution for the multi-points measurement is 4 mm. The calibrating method with the measuring object was developed to realize accurate measurements. During the calibration phase, the object is kept stand-still, and only the sensor head moves by the linear actuator. Thus, the calibration data can be obtained just before the measurement. Several arrangements of the sensor system is available depending on the object to be measured, such as line vibration, surface vibration, and the 3D movement of small object. The developed system has been used for the measurement of the actuators for vibratory microinjection and the measurement of artificial heart valves. Those results showed the advantage of the system. [This study has been supported by JSPS under the Grants-in-Aid for Scientific Research, Nos. 14550427 and 16560369.]
Acoustic sensor structural configuration study.
Authors: Zhang Bill B.B. , Shepard W. Steve
Published: October 2013

This work examines the configuration requirements for a sensor being developed to provide information about the location of an acoustic source. The continuous sensor’s vibrational response, caused by a traveling acoustic wave, is used in an inverse method to reconstruct the forces in that wave. A finite-length beam supported on an elastic foundation is the candidate structure. The impact of changing various structural parameters on the beam’s vibration response is examined analytically using finite element methods. A goal in configuring the beam sensor is to obtain a response with enough dynamic information to accommodate a successful force reconstruction. Some of the configuration parameters of interest include the beam material, geometry, thickness, and the elastic foundation properties. The excitations used in the study consist of transient waves with differing numbers of sinusoidal half-cycles. Because background noise has the potential to impact the force reconstruction, various amounts of white noise are added to the simulated response values prior to performing the traveling wave reconstruction. Tikhonov regularization and the L-curve method are used. Results obtained from the simulations show that this sensor model is effective in identifying moving wave loads. [Work supported by NSF Sensor Innovation and Systems.]
An acoustical comparison of English tense and lax vowels.
Authors: Yang Byunggon
Published: October 2013

Several studies on the pronunciation of English vowels point out that Korean learners have difficulty producing English tense and lax vowel pairs. The acoustic comparisons of those studies are mostly based on the formant measurement at one time point of a given vowel section. However, the English lax vowels usually show dynamic changes across their syllable peaks and subjects’ English levels account for various conflicting results. The purposes of this paper are to compare the temporal duration and dynamic formant tracks of English tense and lax vowel pairs produced by five Korean and five American males. Results showed that both the Korean and American males produced the vowels with comparable durations. The duration of the front tense-lax vowel pair was longer than that of the back vowel pair. From the formant track comparisons, the American males produced the tense and lax pairs much more distinctly than the Korean males. The results suggest that the Korean males should pay attention to the F1 and F2 movements, i.e., the jaw and tongue movements, in order to match those of the American males. Further studies are recommended on the auditorily acceptable ranges of F2 variation for the lax vowels.
The production of new versus similar vowels by Korean-English bilingual children.
Authors: Lee Soyoung , Iverson Gregory
Published: October 2013

The purpose of this study was to compare the vowel productions of Korean-English bilingual children with those of monolingual English and Korean-speaking children. Flege (1987) hypothesized that equivalent classification prevents adult L2 learners from establishing separate phonetic categories for similar phones (which occur in both languages) but not for new L2 phones. This hypothesis, however, has not been fully tested in bilingual children. The present study examined twenty 5-year-old Korean-English bilingual children who had been exposed to both languages for at least 2 years along with their age-equivalent monolingual counterparts, for a total of 60 children. Nine English vowels and six Korean vowels were elicited using picture cards. First and second formant frequencies for similar (/i, ε, u, o, a/) and new (/ɪ, ɔ, ī, æ, i/) vowels were measured. Vowels which were categorized as new were not appreciably different from those of monolinguals, suggesting that bilingual children produce new vowels authentically, consistent with the Flege hypothesis. However, the findings were mixed with respect to similar vowels. Bilingual children produced English vowels similarly to monolingual English-speakers, but their Korean vowels differed from those of monolingual Korean children, implying influence of the dominant (English) over the less-dominant language (Korean).
Cross-linguistic differences in prosodic organization: Evidence from a repetition task.
Authors: Nava Emily , Goldstein Louis
Published: October 2013

The prosody of languages such as English and Spanish has been characterized as exhibiting different rhythmic organizations. English has been hypothesized to organize syllables into feet, with one stressed syllable per foot. Spanish is among the languages whose prosody has been hypothesized to not include the foot, despite the existence of lexical stress in Spanish. We tested the hypothesis that these potential differences in organization would lead to systematically different responses when speakers were asked to entrain a sequence of syllables with a metronome at an increasing rate, and that L1Spanish/L2English speakers would continue to exhibit the Spanish pattern in their English. Speakers of all three types were recorded producing a single repeated syllable, or a sequence of two alternating syllables, in time with a metronome, whose rate increased monotonically after a stabilization period. At slower speech rates, English speakers produced each word as a separate foot with a corresponding pitch accent, while at increased speech rates, two words were grouped together into a single iambic foot with one pitch accent. Spanish speakers and L1Spanish/L2English speakers are expected to shorten both vowels, employing a symmetric strategy (as opposed to the asymmetric strategy of English speakers) to keep pace with the metronome. [Work supported by NIH, NSF.]
Perception of second-language stress and vowel quantity by English learners of Czech.
Authors: Podlipský Václav J.
Published: October 2013

L2 acquisition may involve reattuning the perceptual system so that a cue becomes utilized for a new linguistic purpose. For instance, if vowel duration cues stress in L1 (like in English), whereas in L2 it marks phonological vowel quantity (like in Czech) it is of interest how the perception of stress and of vowel quantity will interact. Previous studies tested if stress affects vowel-quantity perception in such languages; this study explores conversely if vowel quantity affects stress perception in English learners of Czech. Since stress is word-initial in Czech, a word-boundary detection task was used, where stress either fell on a long vowel (stress and vowel length coincided) or on a short vowel, but there was a long vowel distracter in an adjacent syllable (stress and vowel length conflicted). Seventeen L1-English-L2-Czech and 69 Czech listeners were tested. Unexpectedly, natives scored slightly but significantly (p<.05) better when stress and vowel length conflicted than when they coincided. The opposite was true for the non-natives who were only at chance when stress and vowel length conflicted. No correlation between the non-native scores and various indices of L2 proficiency was found. It is concluded that learners transferred L1 perceptual strategies to the L2.