bluuebunny/crossref_metadata_2025 huggingface dataset:
Parameters arising from the Burridge-Keller formulation for poroelastic media, especially for granular media and marine sediments
Authors: Pierce Allan D. , Carey William M. , Barbone Paul E.
Published: October 2013

It was previously shown [Pierce et al. (2006)] that the Burridge-Keller formulation [J. Acoust. Soc. Am. (1981)] rigorously justifies the low-frequency version [(1956a)] of Biot’s equations. Implementation involves two microscale problems: (1) incompressible viscous flow driven in a highly irregular space with rigid walls by a uniformly and externally applied apparent pressure distribution and (2) elastostatic deformation of an intricate elastic web caused by the joint influence of a distributed constant body force and by uniform tractions (including an external pressure) on the web’s exposed surface. Microscale averages produce the Biot ‘‘constants.’’ Theoretical devices of applied mechanics and mathematics yield estimates of these and related parameters. In particular, it is shown that Wood’s equation is a reasonable first approximation for the sound speed in sediments in the low-frequency limit. The formulation also yields an estimation for the sound speed in the high-frequency limit, when the viscous boundary layers become thin. The well-known result that the attenuation varies as f1/2 in the high-frequency limit also results without the necessity of Biot’s heuristic patching theory. Various heuristic approximations due to Gassmann, to Geertsma and Smit, and to Stoll and Bryant are analytically and numerically assessed.
Nonlinear surface waves in soil
Authors: Zabolotskaya Evgenia A. , Ilinskii Yurii A. , Hamilton Mark F.
Published: October 2013

Nonlinear effects in surface waves propagating in soil are investigated theoretically. Analytic solutions are derived for the second harmonics and difference frequency waves generated by a bifrequency primary wave propagating at moderate amplitude. The soil is modeled as an isotropic solid. As such, its elastic properties are described by five elastic constants, two at second order in the strain energy density (the shear and bulk moduli) and three at third order. Nonlinear propagation of the surface waves is based on a theory developed previously [Zabolotskaya, J. Acoust. Soc. Am. 91, 2569–2575 (1992)]. Elements of the nonlinearity matrix associated with the interacting spectral components are expressed in terms of the five elastic constants. It was found convenient to express the nonlinearity matrix for soil as a function of a nonlinearity parameter corresponding to B/A for liquids, particularly for saturated soils exhibiting liquidlike properties. This nonlinearity parameter can vary by several orders of magnitude. For soils with shear wave speeds less than 20% of the compressional wave speeds, the nonlinearity of surfaces waves is found to be independent of the third-order elastic constants and dependent only on the shear modulus. [Work supported by ONR.]
Nonlinear acoustic landmine detection: Comparison of soil nonlinearity with soil-interface nonlinearity
Authors: Korman Murray S. , Pauls Kathleen E. , Genis Sean A. , Sabatier James M.
Published: October 2013

To model the soil-top plate interface in nonlinear acoustic landmine detection, the soil-plate oscillator was developed [J. Acoust. Soc. Am. 116, 3354–3369 (2004)]. A Lexan plate (2.39 mm thick, 18.5 cm diameter) is clamped at an inside diameter of 11.8 cm between two metal flanges. Dry sifted masonry sand (2-cm layer) is placed over the plate. Turning curves experiments are performed by driving a loudspeaker (located over the sand) by a swept sinusoid. The acceleration versus frequency is measured near resonance on a swept spectrum analyzer using an accelerometer centered on the surface. The corresponding backbone curve exhibits a linear decrease in resonant frequency f versus increasing acceleration, where a=−ao(f−fo)/fo. Define a nonlinear parameter α=1/ao. When the elastic plate is replaced by a ‘‘rigid’’ plate, α decreased from 0.128 to 0.070 (s2/m), while fo increased from 191 to 466 Hz. When a cylindrical drumlike mine simulant (rigid walls, thin acrylic top-plate) was buried 2 cm deep in a concrete sand box, ‘‘on the mine’’ results yielded α=0.30 (s2/m) with fo=147 Hz, while ‘‘off the mine,’’ α∼0.03 (s2/m) at fo=147 Hz. [Work supported by ONR.]
Causality conditions and signal propagation in bubbly water
Authors: Orris Gregory J. , Dacol Dalcio K. , Nicholas Michael
Published: October 2013

Acoustic propagation through subsurface bubble clouds in the ocean can exhibit signal travel times with enormous variations depending on the acoustic signal frequency, bubble size distribution, and void fraction. Recent theories have predicted large variations in phase speeds and attenuation that have been largely validated for frequencies well below and well above bubble resonance. However, great care must be exercised when theoretically treating signal propagation at frequencies near resonance, termed the ‘‘Anomalous Absorption Regime’’ nearly 100 years ago in the pioneering work of Sommerfeld [A. Sommerfeld, Physik. Z. 8, 841 (1975)] while investigating aspects of electromagnetic causality. We will discuss similarities between acoustic propagation in bubbly media and electromagnetic propagation in the presence of a conducting medium. We show that the signal travel time is dependent on the behavior of the dispersion formula in the complex frequency plane and place limits on the range of validity of these formulas, leading naturally to the necessary modifications to the current dispersion formulas to bring them into compliance with causality. Finally, we present theoretical results for the velocity of signals for a representative environment of experimental work carried out at the Naval Research Laboratory. [Work supported by the ONR.]
Efficient computation of 3-D acoustical scattering from multiple arbitrarily shaped objects using the boundary element method/fast multipole method (BEM/FMM)
Authors: Gumerov Nail A. , Duraiswami Ramani
Published: October 2013

Many applications require computation of acoustic fields in systems consisting of a large number of scatterers, which may have complex shape. Despite the boundary element method being a well-known technique for solution of the boundary value problems for the Helmholtz equation, its capabilities are usually limited by the memory and speed of computers, and conventional methods can be applicable to relatively small (up to order of 10000 boundary elements) problems. We developed and implemented an efficient computational technique, based on an iterative solver employing generalized minimal residual method in combination with matrix-vector multiplication speeded up with the fast multipole method. We demonstrate that this technique has O(N) memory and computational complexity and enables solution of problems with thousands of scatterers (millions of boundary elements) on a desktop PC. The test problems solved are of moderate frequency (up to kD≤150, where k is the wavenumber and D is the size of the computational domain). Solution of large scale scattering problems was tested by comparison with the FMM-based T-matrix method applicable for simple shape objects reported earlier [Gumerov and Duraiswami, J. Acoust. Soc. Am., 117(4), 1744–1761 (2005)], visualization, and physical interpretation of the results.
Effective parameters of periodic and random distributions of rigid cylinders in air
Authors: Torrent Daniel , Sánchez-Dehesa José
Published: October 2013

The scattering of sound by finite-size clusters consisting of two-dimensional distributions (periodic and random) of rigid cylinders in air is theoretically studied in the low-frequency limit (homogenization). Analytical expressions for the effective density and sound speed obtained in the framework of multiple scattering will be reported. For the case of circular-shaped cluster, we have theoretically analyzed the homogenization as a function of the filling fraction, the type of arrangement of the cylinders in the cluster (hexagonal and square lattice), and the number of cylinders in the cluster. When the number of cylinders in the cluster is small we found that for certain ‘‘magic numbers’’ their effective parameters (sound speed and density) are the same as those of the corresponding infinite array. [Work supported by MEC of Spain.]
The application of k-space acoustic propagation models to biomedical photoacoustics
Authors: Cox Benjamin T. , Arridge Simon. R. , Beard Paul C.
Published: October 2013

k−space models for broadband acoustic pulse propagation differ from pseudo−spectral time domain (PSTD) models in their treatment of the time step. By replacing a finite−difference scheme with a propagator, exact for homogeneous media, larger time steps can be taken without loss of accuracy or stability and without introducing dispersion. Three k−space models for modeling photoacoustically generated (PA) pulses are described here. A very simple, exact, model of PA propagation in a homogeneous fluid is used to introduce the k−space propagator, and two models of propagation in heterogeneous media, originally designed for modeling scattering in soft tissue, are adapted for use in photoacoustics [Mast et al., IEEE Trans. UFFC 48, 341−354 (2001); Tabei et al., J. Acoust. Soc. Am. 111, 53−63 (2002)]. Our motivation for describing these models comes from biomedical PA imaging, in which one of the current limitations is the assumption that soft tissue has a uniform sound speed. Efficient, accurate, and simple−to−encode forward models such as these are very useful for studying the effects of the heterogeneities encountered in practice. They may also be useful in designing PA imaging schemes that can account for acoustic heterogeneities. [This work was funded by the EPSRC, UK]
Emergence of the acoustic Green’s function from thermal noise
Authors: Godin Oleg A.
Published: October 2013

Recently proposed applications of noise cross-correlation measurements to passive remote sensing range from ultrasonics and acoustic oceanography to helioseismology and geophysics, at wave frequencies that differ by more than ten orders of magnitude. At the heart of these applications is the possibility to retrieve an estimate of a deterministic Green’s function from long-range correlations of diffuse noise fields. Apparently, S. M. Rytov [A Theory of Electrical Fluctuations and Thermal Radiation (USSR Academy of Sciences, Moscow, 1953)] was the first to establish theoretically a simple relation between the Green’s function and the two-point correlation function of fluctuations of wave fields generated by random sources. He used reciprocity considerations to analyze fluctuations of electromagnetic fields. In this paper, an acoustic counterpart of Rytov’s approach is applied to derive exact and asymptotic relations between respective acoustic Green’s functions and cross-correlation of thermal noise in inhomogeneous fluid, solid, and fluid-solid media. Parameters of the media are assumed to be time independent, but can be arbitrary functions of spatial coordinates. Theoretical results obtained are compared to those previously reported in the literature.
Comparison of time reversal acoustic and prefiltering methods of focusing of tone burst signals
Authors: Choi Bok Kyoung , Sutin Alexander , Sarvazyan Armen
Published: October 2013

The concept of time reversal acoustics (TRA) provides an elegant possibility of both temporal and spatial concentration of acoustic energy in highly inhomogeneous media. TRA-based focusing is typically used for generation of short acoustic pulses, however, in some medical and industrial applications, longer pulses are required. TRA focusing of longer signals leads to an increase of side lobes in temporal and spatial domains. Another method for focusing, known as prefiltering, is based on measurements of the impulse response, which relates the signal at the TRA transmitter to that at the focusing point. After evaluating the impulse response, the excitation signal may be calculated to generate the desired waveform in the focus point. This method allows signal generation with any desired form including long tone-burst signals. Experiments on comparison TRA and prefiltering methods of ultrasound focusing were conducted in the frequency band of 200–1000 kHz. In the experiments, focused acoustic pulses with various forms and duration were generated: triangular, rectangular, and amplitude-modulated tone burst signals. The prefiltering modes provide better temporal compression of the focused signal, and the signal energy outside the main pulse in the prefiltering mode was shown to be much lower than that in standard TRA focusing.
An electrophysiological measure of basilar membrane nonlinearity in humans
Authors: Plack Christopher J. , Krishnan Ananthanarayan
Published: October 2013

A behavioral measure of the basilar membrane response can be obtained by comparing the growth in forward masking for maskers at, and well below, the signal frequency. Since the off-frequency masker is assumed to be processed linearly at the signal place, the difference in masking growth with level is thought to reflect the compressive response to the on-frequency masker. The present experiment used an electrophysiological analog of this technique, based on measurements of the latency of wave V of the auditory brainstem response elicited by a 4-kHz, 4-ms pure tone, presented at 65 dB SPL. Responses were obtained in quiet and in the presence of either an on-frequency or an off-frequency (1.8 kHz) pure-tone forward masker. Wave V latency increased with masker level, although the increase was greater for the off-frequency masker than for the on-frequency masker, consistent with a more compressive response to the latter. Response functions generated from the data showed the characteristic shape, with a nearly linear response at lower levels, and 5:1 compression at higher levels. However, the breakpoint between the linear region and the compressive region was at about 60 dB SPL, higher than expected on the basis of previous physiological and psychophysical measures.
Energy finite energy analysis for shipboard noise
Authors: Fischer Raymond , Boroditsky Leo , Gilfroy Layton , Brennan David
Published: October 2013

Machinery-induced habitability noise is difficult to model efficiently and accurately. The potential of energy finite-element analysis (EFEA) is compared to other prediction tools such as statistical energy analysis (SEA). This paper will explore the benefits and costs of EFEA with respect to SEA for acoustic modeling. The focus will be on issues relating to structural modeling for EFEA purposes. EFEA techniques will be evaluated to see if they possess the capabilities of verified SEA approaches for predicting habitability and radiated noise, where it is necessary to account for the impact of diverse marine constructions and sources such as the lack of machinery source information with respect to force or moment inputs or the finite impedance of machinery foundations. The effort proposed herein will provide the necessary engineering to research and identify salient features of EFEA that are potentially applicable for the detailed analysis of the acoustic environment and response of surface ships to various excitation sources. The paper will also address the pros and cons of SEA versus energy-finite element analysis (EFEA) methods used to predict the habitability noise of surface ship platforms. [This work is supported by an Office of Navy Research contract.]
Spectral-based multicoordinate substructuring model for vehicle noise, vibration, and harshness refinement
Authors: Lim Teik C.
Published: October 2013

The success of vehicle NVH (noise, vibration, and harshness) refinement often depends on the ability to identify and understand noise and vibration transmission paths within the mid-frequency range, i.e., 200–1000 Hz, throughout the assembled structure. Due to the complexity of the dynamics in this frequency range, most modal or finite element-based methods do not possess the fidelity needed. To address this gap, a multicoordinate substructuring theory applying measured structural-acoustic and vibration spectra is applied. Three forms of substructuring formulation, namely the nondiagonal, block-diagonal, and purely diagonal coupling cases, are developed. The performances of these approaches are studied numerically, and the net effects of these coupling formulations on the predicted joint and free substructure dynamic characteristics, and system response, are determined. Conditions for applying the simpler coupler that can simplify the testing process and overcome computational deficiencies are also derived. When the measured data is noise contaminated, the singular value decomposition (SVD) algorithm is found to be quite helpful. Using an actual vehicle, a comprehensive analysis of the measured and predicted vehicle system responses is performed. The results are employed to develop an understanding of the primary controlling factors and transfer paths and to cascade system requirements to the substructure level.
Practical application of digital simulation with physical test in vehicle virtual
Authors: Abe Toshiro
Published: October 2013

In the current vehicle design and development program, the Virtual Product Development process (hereafter, VPD process) is the innovation for automotive industry, which improves product quality and shortens time to market. In general, valid CAE applications are the key component of the VPD process as well as physical tests being indispensable to create valid simulation technologies. This presentation explains how physical-test-based CAE leverages the VPD process. In particular, the presentation is based on how physical testing supports the VPD process and why the ESTECH philosophy is that ‘‘The essence of CAE lies in its synergy with Testing;’’ a philosophy that differentiates the company from the competition. To demonstrate these activities, case studies based on automotive dynamic and real time simulation will be presented. In the case studies, vehicle body NVH and brake noise analysis will be used to show the interaction between physical test and computer simulation. Finally, practical application of the VPD process in one of the leading Japanese automotive companies will be shown, where the effectiveness of the front loading in the actual vehicle development program and the actual deployment of VPD process to the Functional Digital Vehicle project in the powertrain design are to be presented.
Radiation from vibrating panels at high frequency including an inquiry into the role of edges and drive points
Authors: Bliss Donald
Published: October 2013

In the high frequency limit, a vibrating finite panel is shown to have broadband power and directivity characteristics that can expressed analytically by a limited set of parameters. Two-dimensional problems with subsonic structural wave speed are considered. Three basic directivity patterns are identified, associated with right and left traveling waves and the correlation between them. The role of boundary conditions at the panel edge is illustrated, as are the effects of types of forcing. Overall, relatively simple broadband behaviors are revealed. The analytical characterization of the radiation is shown to be particularly straightforward in the high frequency broadband limit. Interestingly, the radiated mean-square pressures are independent of the panel length, indicating the radiation is associated with the edges and the drive point. However, the radiation patterns cannot be explained in terms of simple volumetric sources placed just at the edges and the drive point, showing that the often-stated idea of uncanceled volumetric sources at these locations is not correct except under very restricted circumstances. A correct physical interpretation of the radiation is provided both in physical space and in terms of spatial Fourier transforms.
Wave propagation characteristics of an infinite fluid-loaded periodic plate
Authors: Sarkar Abhijit , Sonti Venkata R.
Published: October 2013

A 1-D infinite periodic plate with simple supports placed along equidistant parallel lines is considered using the finite-element method. The plate is loaded with a finite-height fluid column covered on the top with a rigid plate. Results show a relation between the propagation constant of the fluid-loaded structure with its in vacuo counterpart. Since the acoustic medium is an additional wave carrier, the attenuation bands corresponding to the in vacuo structure turn out to be propagating. However, the presence of the fluid can also bring about attenuation regions within the in vacuo propagation bands. Primary propagation constants bring additional waves called space harmonics with them. Hence, a localized coincidence effect is seen where a particular harmonic falls below or above the acoustic wave number, leading to propagation or a mass loading effect. Occasionally, a complete attenuation band is created. This is verified by decomposing the single span displacement profile into the space harmonics and also by computing the frequency response function (FRF) for a finite fluid-loaded periodic plate and observing the huge antiresonance dip in frequency in the exact same frequency band where an attenuation band was predicted for the infinite structure.
Symbolic phonetic features for pronunciation modeling
Authors: Bates Rebecca A. , Ostendorf Mari , Wright Richard A.
Published: October 2013

A significant source of variation in spontaneous speech is due to intraspeaker pronunciation changes, often realized as small feature changes, e.g., nasalized vowels or affricated stops, rather than full phone transformations. Previous computational modeling of pronunciation variation has typically involved transformations from one phone to another, partly because most speech processing systems use phone-based units. Here, a phonetic-feature-based prediction model is presented where phones are represented by a vector of symbolic features that can be on, off, unspecified, or unused. Feature interaction is examined using different groupings of possibly dependent features, and a hierarchical grouping with conditional dependencies led to the best results. Feature-based models are shown to be more efficient than phone-based models, in the sense of requiring fewer parameters to predict variation while giving smaller distance and perplexity values when comparing predictions to the hand-labeled reference. A parsimonious model is better suited to incorporating new conditioning factors, and this work investigates high-level information sources, including both text (syntax, discourse) and prosody cues. Detailed results are under review with Speech Communication. [This research was supported in part by the NSF, Award No. IIS-9618926, an Intel Ph.D. Fellowship, and by a faculty improvement grant from Minnesota State University Mankato.] a)Currently at Minnesota State University, Mankato.
Intertalker differences in intelligibility of cochlear-implant simulated speech
Authors: Bent Tessa , Buchwald Adam B. , Pisoni David B.
Published: October 2013

Are the acoustic-phonetic factors that promote highly intelligible speech invariant across different listener populations? Two approaches have been taken to investigate intelligibility variation for a variety of listener populations including hearing-impaired listeners, second language learners, and listeners with cochlear implants: studies on how speaking style affects intelligibility and other research on how inherent differences among talkers influence intelligibility. Taking the second approach, we compared intertalker differences in intelligibility for normal-hearing listeners under cochlear implant (CI) simulation (n=120) and in quiet (n=200). Stimuli consisted of 20 native English talkers’ productions of 100 sentences. These recordings were processed to simulate listening with an eight-channel CI. Both clear and CI-processed tokens were presented to listeners in a sentence transcription task. Results showed that the most intelligible talkers in quiet were not the most intelligible talkers under CI simulation. Furthermore, listeners demonstrated perceptual learning with the CI-simulated speech but showed little learning in the quiet. Some of the acoustic-phonetic properties that were correlated with intelligibility differed between the CI-simulated speech and the speech in the quiet. These results suggest that the intertalker variations that result in highly intelligible speech observed in earlier studies are dependent on listener characteristics. [Work supported by NIDCD.]
Phoneme dependency of accuracy rates in familiar and unknown speaker identification
Authors: Amino Kanae , Arai Takayuki , Sugawara Tsutomu
Published: October 2013

For perceptual speaker identification, the identification accuracy depends on the speech contents presented to subjects. Our previous studies have shown that stimuli containing nasals are effective for identifying familiar speakers [Amino et al., Acoust. Sci. Tech. 27(4) (2006)]. We have also presented the possibility that the interspeaker spectral distances reflect perceptual speaker similarities. In the present study, we conducted an experiment in which four unknown speakers were identified by 15 subjects. The stimuli were identical to those used in the previous study, in which ten speakers were identified by familiar listeners, although the speakers were fewer this time. Nine consonants in the CV structure were used as stimuli. The consonants were /d/, /t/, /z/, /s/, /r/, /j/, /m/, /n/, and /nj/; the vowel was restricted to /a/ for all CV syllables to simplify the experiment. The results showed that the nasals /n/ and /nj/ obtained higher scores. Tendencies in the differences among consonants were on the same order as those of the previous experiment, but the average scores were lower than those for familiar listeners. [Work supported by Grant-in-Aid for JSPS Fellows 17-6901.]
Perceived vocal age and its acoustic correlates
Authors: Kido Hiroshi , Kasuya Hideki
Published: October 2013

This study investigates relationships between perceived and chronological age of talkers and acoustic correlates of the perceived age. Most of the past studies were primarily concerned with the instability of the vocal-fold vibration extracted from sustained vowels. This study focuses on the dynamic nature of sentence utterances. Talkers included 115 healthy men, aged 20–60 years, who read a short sentence in Japanese. Listeners consisted of 70 men and women, aged 20–40 years, who made direct estimations of age. The results showed a strong correlation (r=0.66) between the perceived and chronological age as well as the tendency toward overestimating the ages of younger talkers and underestimating those of older talkers, supporting past investigations [e.g., R. Huntley et al., J. Voice 1, 49–52 (1987)]. Acoustic parameters considered were median of the fundamental frequency (F0) contour, F0 range, declination of F0 contour, spectral tilt, median of the boundary frequencies above which irregularities dominate, and speaking rate. From both statistical graphical modeling and regression tree analysis, the speaking rate, F0 declination, and spectral tilt were found to be dominant acoustic correlates to the perceived age. [Work supported partly by a Grant-in-Aid for Scientific Research, JSPS (16300061).]
Cross-linguistic differences in speech perception
Authors: Johnson Keith , Babel Molly
Published: October 2013

This research explores language-specific perception of speech sounds. This paper discusses two experiments: experiment 1 is a speeded forced-choice AX discrimination task and experiment 2 is a similarity rating task. Experiment 1 was intended to investigate the basic auditory perception of the listeners. It was predicted that listeners’ native languages would not influence responses in experiment 1. Experiment 2 asked subjects to rate the similarity between two tokens on a five-point equal interval scale; the purpose of this experiment was to explore listeners’ subjective impression of speech sounds. In experiment 2 it was predicted that listeners’ language would affect their responses. The same stimuli were used in both experiments. The stimuli consisted of vowel-fricative-vowel sequences produced by a trained phonetician. Six fricatives were used: /f, th, s, sh, x, h/. These fricatives were embedded in three vowel environments: /a—a/, /i—i/, and /u—u/. Tokens were presented to listeners over headphones with a 100-ms interval. Independent groups of 15 native Dutch and English listeners participated in each of the two experiments. Results suggest that listeners’ language influenced responses in both experiments, albeit the result was larger in experiment 2. [Work supported by NIH.]
An analysis of acoustic deviation manner in spontaneous speech
Authors: Hosogai Norimichi , Okita Kanae , Aida Takuya , Okawa Shigeki
Published: October 2013

Natural speech typically contains various phenomena deviated from the formal mode such as read speech. It is well known that those paralinguistic phenomena have an important role to give the human emotions and the state of the speakers in speech communication. This study attempts to extract the deviation as an acoustic ‘‘vagueness,’’ defined by temporal and dynamical acoustic features of speech. Especially the change of the vagueness during a certain period of speech, such as a 10-minute presentation, is focused. As the acoustic features, it used (i) modulation spectrum and (ii) syllable speed, which may have relations to the speech clarity and the tempo. For the experiments, 70 academic presentation speech data in the Corpus of Spontaneous Japanese (CSJ) are used. As the experimental results, significant properties in the patterns of the modulation spectrum and the syllable speed are obtained as a difference of the beginning and the ending periods of the presentation. This result will contribute to a humanlike speech dialog system.
Region, gender, and vowel quality: A word to the wise hearing scientist
Authors: Wright Richard , Bor Stephanie , Souza Pamela
Published: October 2013

Sociophonetic research has established effects of regional accent and gender on spoken vowels. Many gender differences are due to sociolinguistic factors and thus vary by region. The implications for researchers and clinicians are important: gender variation must be controlled for according to the region of the listener and talker population. Moreover, speech perception stimuli used in research and in clinical applications have limited regional application. This poster illustrates these factors using the Pacific Northwest regional accent. The data, collected for a previous study on hearing aid processing, consist of three repetitions of eight vowels produced in real-word /h—d/ (or /—d/) contexts by six males and six females ranging in age from 19 to 60. Formants were measured using an LPC with an accompanying FFT and spectrogram for verification. The results revealed vowel-specific differences in the male and female speech over and above those typically associated with physiologic predictions, and different again from those observed in past studies from different regions. Taken as a whole, these data suggest that speech and hearing researchers should take care in selecting stimuli for general-use speech perception tests. [Work supported by NIDCD training grant (♯DC00033) and NIH RO1 (1 RO1 DC006014).]
Acoustic characteristics of vowels in three regional dialects of American English
Authors: Jacewicz Ewa , Fox Robert Allen , Holt Yolanda , Salmons Joseph
Published: October 2013

Most of the comparative sociophonetic studies of regional dialect variation have focused on individual vowel differences across dialects as well as speaker variables. The present work seeks to define basic acoustic characteristics of entire vowel systems for three different regional variants of American English spoken in southeastern Wisconsin (affected by the Northern Cities Shift), western North Carolina (affected by the Southern Vowel Shift), and central Ohio (not considered to be affected currently by any vowel shift). Three groups of speakers (men and women) aged 20–29 years were recorded from each geographic area defined by two to three counties (creating a highly homogeneous set of speakers). Acoustic measures for the set of 14 monophthongs and diphthongs in /h—d/ context included vowel space area for each speaker, global spectral rate of change for diphthongized vowels (defined over the first three formant slopes), the amount of frequency change for F1 and F2 at two temporal points located close to vowel onset and offset (vector length), and vowel duration. These measures will establish both systemic and vowel inherent characteristics across the three dialects, serving as a basis for future examination of conditioning factors on vowels in chain shifts. Dialectal differences will be discussed. [Work supported by NIH NIDCD R01 DC006871.]
Restricting relativized faithfulness and local conjunction in optimality theory
Authors: Fukazawa Haruka
Published: October 2013

Within the framework of optimality theory (OT), the two mechanisms, relativized faithfulness and local conjunction, play inevitable roles, especially when a simple constraint ranking fails to account for the data. However, their domain of application are too unrestricted and even overlapping each other. For instance, there are some cases which could be explained both by the ranking with relativized faithfulness and by the one with local conjunction. Syllable-final neutralization in German and geminate devoicing in Japanese loanwords are of interest in this context. The present paper proposes formal restrictions mostly on the local conjunction mechanism: the soundness of constraint combination, the number of constraints involved in a conjunction, and the local domain of conjunction. They not only can simplify the analysis but also give a more principled account for the overlapping cases. In fact, relativized faithfulness approach wins over local conjunction approach both in German neutralization and in Japanese loanwords. It is desirable for the universal grammar to be more restricted. Removing an overlap of theoretical devices is an important step toward the goal.
Why we should design for optimum reverberation times in rooms for speech communication
Authors: Bradley J. S.
Published: October 2013

Various texts list recommendations for optimum reverberation times as ideal goals in rooms for speech communication. However, some newer documents, such as ANSI S12.60, talk about maximum recommended reverberation times in rooms for speech communication. The source of the changed approach can be traced to interpretations of experimental results that do not consider the full implications for speech communication in real rooms, and also to the fact that reverberation time is not an ideal predictor of the quality of speech communication. In the extreme, minimizing reverberation times would lead to near anechoic rooms for speech and inadequate signal-to-noise ratios. The need for optimum reverberation times can be explained as a simple need to first achieve adequate signal-to-noise ratios. However, a more complete understanding is obtained by examining the benefits of early-arriving reflections of speech sounds on the intelligibility of the speech to listeners. Attempts to determine optimum reverberation times for normal hearing listeners, which are based on a balance between avoiding excessive reverberation and maintaining adequate signal-to-noise ratios, lead to a range of acceptable values that can vary with the ambient noise level. This discussion will be supported with examples from room acoustics measurements in classrooms and meeting rooms.
The relation between speech transmission index, clarity, and reverberation time and listening difficulty in the impulse response database of AIJ
Authors: Sato Hiroshi , Nishikawa Yoshio , Sato Hayato , Morimoto Masayuki
Published: October 2013

The Speech Communication Research Working Group of AIJ (Architectural Institute of Japan) is collecting information on rooms including digitized impulse responses (IRs) to establish a database for evaluating and designing the speech transmission quality of rooms. This database consists of 966 measured IRs. This study presents the relationships between speech transmission index (STI), clarity (Cx) and reverberation time (T) as measures to consider for the design and evaluation of the speech transmission performance of rooms. The data show a wide range of STI and Cx values for a given T, and the minimum STI at each reverberation time can be obtained by diffused field theory. STI and Cx are seen to be better indicators than T for the design of rooms for speech and that T is not as good. Relationships between STI, Cx, and listening difficulty ratings from previous studies [Proc. of RADS (2004), Proc. of Forum Acusticum, pp. 1713–1718 (2005)] found both STI and Cx can be used as predictors of listening difficulty ratings. Finally, listening difficulty ratings of individual IR in the database are estimated and the distribution of listening difficulty ratings in a variety of rooms are presented as a solid bases to design speech transmission quality of rooms.
Influence of word familiarity on spoken word recognition
Authors: Amano Shigeaki , Kondo Tadahisa , Sakamoto Shuichi , Suzuki Yôiti
Published: October 2013

Spoken word recognition is affected by many factors including sound pressure level, signal-to-noise ratio, word familiarity, word frequency, and phoneme sequence plausibility. Of these factors, word familiarity is assumed to have a strong effect but has received little attention. One reason for this is that word familiarity data for most words have been unavailable. However, we can now confirm the word familiarity effect because in 1999 Amano and Kondo published a word familiarity database for about 80000 Japanese words. Experimental results clearly show that spoken words with a high familiarity are recognized better and faster than those with a low familiarity. In addition, word familiarity correlates with the recognition score of spoken words much better than word frequency, which was previously regarded as an influential factor in word recognition. Because the word familiarity effect is so strong, it is very important to control the familiarity of spoken words to obtain stable and reasonable results when assessing the speech hearing ability of individuals, and when measuring speech clarity in communication media and public spaces.
Preprocessing speech against reverberation
Authors: Arai Takayuki
Published: October 2013

Although short reverberation in a room may help speech perception, it is known that long reverberation causes degradation in speech comprehension. This is especially true for elderly people, the hearing-impaired, and non-native listeners. In order to prevent intelligibility degradation, we can apply a signal processing technique to the public address system of a room before speech signals are radiated through the loudspeakers. So far, we have developed several such preprocessing techniques. The two main techniques are modulation filtering [Kusumoto et al., Speech Commun. 45, 101–113 (2005)] and steady-state suppression [Arai et al., Acoust. Sci. Technol. 23, 229–232 (2002)]. Both techniques essentially enhance the temporal dynamics of speech between 1 and 16 Hz [Arai et al., J. Acoust. Soc. Am. 105, 2783–2791 (1999)]. Steady-state suppression, which suppresses steady-state portions of speech, reduces overlap-masking and improves speech intelligibility for young, elderly, and non-native listeners in reverberant environments [e.g., Hodoshima et al., J. Acoust. Soc. Am. 119, 4055–4064 (2006)]. This technique is more effective when speech-rate slowing is applied in advance [Arai et al., Acoust. Sci. Tech. 26, 459–461 (2005)]. Intelligibility with this technique exceeds a simple speech-rate slowing approach. [Work partially supported by JSPS.KAKENHI (16203041).]
Failure of the precedence effect in children and in persons with hearing loss
Authors: Litovsky Ruth
Published: October 2013

Children spend a vast majority of time in reverberant environments. However, their auditory system appears not to be as fully equipped as that of adults for coping with reverberation. In our studies we simulate simple aspects of reverberation by exploiting a well-known auditory illusion known as the precedence effect (PE). Stimuli consist of clicks or speech, pairs of source (lead), and its first-arriving reflection (lag). Results from typically developing normal-hearing children ages 3–10 suggest that the PE undergoes significant maturation during childhood. In addition, we studied 10-year-old children with specific language impairment (SLI), who are delayed on expressive and receptive language. Performance was similar to that of younger, language-age-matched children, suggesting that the PE could be a useful clinical tool for measuring nonverbal temporal information processing. The PE was also used to study deaf adults with bilateral cochlear implants. Results suggest that binaural sensitivity is only available when the cochlea can be directly stimulated, but in free field the temporal smearing caused by the microphone leads to degraded and abnormal PE. Taken together, these studies suggest that a basic and necessary auditory function, that of suppressing echoes, fails under numerous circumstances, in children and in deaf, bilateral cochlear implant users.
Voices of the dead: Complex nonlinear vocal signals from the larynx of an ultrasonic frog
Authors: Suthers Roderick A. , Narins Peter M. , Lin Wen-Yu , Schnitzler Hans-Ulrich , Denzinger Annette , Xu Chun-He , Feng Albert S.
Published: October 2013

Most anurans are highly vocal but their vocalizations are stereotyped and simple with limited repertoire sizes compared to other vocal vertebrates, due presumably to the limited mechanisms for fine vocal motor control. We recently reported that the call of the concave-eared torrent frog (Amolops tormotus) is an exception in its seemingly endless variety, musical warbling quality, extension of call frequency into the ultrasonic range, and the prominence of nonlinear features such as period doubling. We now show that the major spectral features of its calls, responsible for this frog’s vocal diversity, can be generated by forcing pressurized air through the larynx of euthanized males. Laryngeal specializations for ultrasound appear to include very thin portions of the medial vocal ligaments and the reverse sexual size dimorphism of the larynx being smaller in males than in females. The intricate morphology of the vocal cords, which changes along their length, suggests that nonlinear phenomena likely arise from complex nonlinear oscillatory regimes of separate elastically coupled masses. Amolops is thus the first amphibian for which the intrinsic nonlinear dynamics of its larynx, a relatively simple and expedient mechanism, can account for the species call complexity, without invoking sophisticated neuromuscular control.
Evaluation of the auditory capabilities of marine mammals using a portable auditory-evoked potential system
Authors: Taylor Kristen A. , Nachtigall Paul E. , Mooney T. Aran , Yuen Michelle M. , Supin Alexander Ya
Published: October 2013

There is growing concern about the increasing amounts of acoustic pollution in our oceans. Anthropogenic noise sources span a large range of frequencies and amplitudes. The extents to which these noise sources adversely impact marine mammals is poorly understood yet they are of particular significance given that the acoustic environment is crucial for many aspects of marine mammal life. Past and present experiments have addressed the effects of different sounds on the hearing capabilities of captive dolphins. However, only a few individuals from a small number of species have been tested. Our research group has created a portable system that is capable of measuring the hearing thresholds of marine mammals using auditory-evoked potential (AEP) techniques. This portable system has enabled us to obtain audiograms of otherwise inaccessible marine mammal species. This system will also allow us to measure the hearing of stranded animals as well as begin to quantify the normal variations in hearing between different ages and genders of animals in captivity.
The physoclistous swim bladder of chaetodontid butterflyfishes: Implications for acoustic function
Authors: Woods Christopher , Webb Jacqueline , Ketten Darlene
Published: October 2013

Butterflyfishes (genus Chaetodon) have a swim bladder lateral line connection (laterophysic connection, LC), hypothesized to convert sound-induced oscillations of the swim bladder into fluid flow in the lateral line system and/or ear. Evaluation of LC function is dependent upon an understanding of swim bladder acoustics, which is a function of swim bladder anatomy. We used several anatomical methods (including CT) to describe swim bladder and tunica externa and tunica interna morphology (including gas gland/rete mirabile complex and the oval, responsible for gas secretion and resorption) in Chaetodon and Forcipiger. Swim bladder and tunica externa morphology differ between Chaetodon spp. with different LCs morphologies. A perforated transverse diaphragm divides the gas volume into two compartments. The gas gland/rete mirabile complex is in the ventral midline of the anterior compartment; it varies in morphology and is largest in species with a direct LC. The oval, defined by an extensive capillary network, occupies the entire tunica interna of the posterior compartment, so that diaphragm position determines oval size. These data raise questions about swim bladder structure-function relationships with respect to the reception and transduction of acoustic stimuli in coral reef fishes. [Work supported by NSF Grant IBN-0132607 to J.F.W.]
The temporal resolution of goldfish hearing: An auditory evoked potential study of gap detection
Authors: Xiao Jianqiang , Braun Christopher
Published: October 2013

Temporal processing in goldfish (Carassius auratus) was studied by measuring auditory evoked potentials (AEP) using gaps in continuous band-limited Gaussian noise. Long (>100 ms) silent gaps in high amplitude noise (30 dB SL) evoked distinct offset and onset responses, lasting 6090 ms. Offset and onset responses overlapped with shorter gaps and became difficult to distinguish for gaps <10 ms. The gap-response waveform was modeled as the sum of offset and temporally-shifted onset responses from the same animals (using 120-ms gaps). This model predicted the waveform of gap responses nearly perfectly for gaps longer than 6 ms. Waveforms evoked by shorter gaps (<6 ms) did not accurately fit this model, suggesting that one or both components of the gap response were inhibited or altered. Nonetheless, clear responses were evoked by gaps shorter than 1 ms at this intensity, while longer gaps (up to 10 ms) were required for detection in a low-intensity noise background. This study extends and confirms prior reports that the temporal resolution for goldfish is on the order of 1 ms, but there is also evidence for longer integration processes, over a period of several ms. [Work supported by Grants S06GM60654, R03MH067808, RR03037 (NIH).]