bluuebunny/crossref_metadata_2025 huggingface dataset:
Inverse characterization of poro-elastic materials based on acoustical input data.
Authors: Bolton J. Stuart , Hong Kwanwoo
Published: October 2009

It has become popular to estimate the Biot parameters of poro-elastic media by using inverse methods. That is, measurements of absorption coefficient and/or transmission loss are used as inputs to an optimization procedure that adjusts the Biot parameters to match the measurements. Software packages are available to perform these operations. To be successful, the models used to match the data must accurately represent the physics of the measurement. However, existing software are based on transversely infinite, layered systems. Such models cannot represent data measured in standing wave tubes when the elasticity of the edge-constrained sample is significant. Here, an approach based on a finite element model of the sample in the tube will be described. It will be demonstrated that this approach makes it easier to estimate the stiffness parameters of a porous sample. Further, a technique involving singular value decomposition of a sensitivity matrix derived from a linearized representation of the absorption coefficient and transmission coefficient near the solution point will be introduced. This procedure gives a clear indication of how many parameters can be estimated from a given data set and gives guidance as to the type of data and the frequency ranges that give the best results.
Indirect acoustical characterization of sound absorbing materials.
Authors: Panneton Raymond , Salissou Yacoubou
Published: October 2009

This paper discusses methods to evaluate the dynamic properties of sound absorbing materials (fibers, foams, etc.) based on impedance tube measurements, and the use of indirect methods to retrieve the main macroscopic material parameters from the dynamic properties. For the methods to be successful, the measured dynamic properties need to follow accurately an equivalent fluid behavior and show little noise, particularly at low frequencies. To improve the quality of these measurements, a modification is proposed to an existing three-microphone transfer matrix approach. The modified approach can also be applied to deduce with precision the transmission loss of homogeneous and non-homogeneous symmetrical or non-symmetrical samples. A comparison of the methods and the obtained macroscopic properties (porosity, tortuosity, static viscous and thermal permeabilities, and characteristic lengths) is discussed.
Modeling noise control treatments attached to sandwich-composite panels.
Authors: Osman Haisam , Atalla Noureddinne
Published: October 2009

This paper discusses the air-borne and structure-borne insertion losses of acoustic materials attached to sandwich-composite panels. The main structure is modeled using an analytical model using discrete layer theory. In this model, all layers of the panel are assumed orthotropic, and both symmetric and anti symmetric modes of propagation are accounted for. For both air-borne and structure-borne excitations, the transfer matrix method with finite size effect correction is used to account for the effect of the noise control treatment. Moreover, power balance is used to highlight the effect of the acoustic treatments in terms of added damping. A three dimensional finite element modeling based on the mixed (u,p) formulations for poroelastic materials and a sandwich element for the structure is presented and used to validate the model. Several examples including sandwich composite panels and various noise control treatments (foams versus fibers, effect of a resistive screens, etc.) are presented and compared.
Investigation of airborne versus structure-borne insertion loss of acoustic materials attached to a flat panel.
Authors: Rhazi Dilal , Atalla Noureddine
Published: October 2009

This paper discusses methods to predict airborne and structure-borne insertion loss of acoustic materials (fiber, foams, etc.) in single wall and double wall configurations attached to various structures. Specifically, a transfer matrix method based approach is proposed and compared to finite element and statistical energy analysis based predictions. Based on several numerical and experimental results, it is shown first that this method presents a simple and general model that can handle easily and automatically practical configurations. Next, a systematic comparison of structure-borne versus airborne excitation is presented for various structures and sound packages. In particular, the effect of damping and nature of coupling between the sound package and the main structure is discussed.
Experimental and numerical comparison of acoustic performance of sound packages with viscoelastic damping or equivalent mass as treatments to flat aluminum panel.
Authors: Cintosun Esen , Stecenko Tatjana , Atalla Noureddine
Published: October 2009

Acoustic performance parameters of airborne and structure-borne insertion loss were compared experimentally and numerically for sound packages with viscoelastic damping or equivalent mass. Transfer matrix method and finite element method were used to perform the numerical analysis. Viscoelastic material damping and equivalent mass (as part of sound packages) were compared as treatments to an aluminum flat panel. The sound packages were made up of either fiberglass or foam in addition to viscoelastic material damping or equivalent mass. The viscoelastic material damping used in this study is constraining layer damping (CLD). The equivalent mass was a solid material with the same surface weight of CLD. As part of the analysis, aluminum panel with and without sound package was subjected to diffuse acoustic field and point force mechanical excitations. The experimental and numerical results both show the same trends. [Work supported by MTI Polyfab Inc.]
Speech intelligibility in speech noise: A perceptual training study.
Authors: Van Engen Kristin J.
Published: October 2009

The ability to understand speech in noisy conditions is not well predicted by the traditional audiogram or by an individual’s ability to understand speech in quiet. Furthermore, listeners with different language backgrounds (e.g., native versus non-native listeners) are affected differentially by the presence of noise, and listeners of a given native language experience more interference from background noise in their native language versus in a foreign language. Given these observations, it is hypothesized that the capacity to tune into target speech and tune out interfering speech noise is subject to experience-related modification and as such should be trainable. The objective of this study is to identify training parameters than can best enhance speech-in-speech intelligibility. To do this, we employ a multiple-talker training paradigm and three between-subjects training conditions: training in speech-shaped noise (a high energetic masker), in English two-talker babble (a high informational masker), and in Mandarin two-talker babble (a lower-energetic/lower-informational masker). By administering a common speech-in-speech post-test, the comparison of these training conditions allows us to begin to isolate the most trainable processes involved in speech-in-speech intelligibility. This approach also allows us to investigate whether training can mitigate the previously observed detrimental effects of native-language noise versus foreign-language noise.
The effect of occluded auditory feedback on articulatory learning.
Authors: Lipski Silvia , Unger Stefanie , Grice Martine , Meister Ingo
Published: October 2009

Auditory and somatosensory feedback are both claimed to be important for the acquisition and control of speech, especially during the learning of new speech sounds, where auditory feedback is said to provide a corrective signal for motor control. This study investigated adult speakers’ speech motor learning capacity in the absence of auditory feedback on a contrast which has clear somatosensory feedback. Thirty German speakers were trained to produce a non-native singleton-geminate contrast on voiceless unaspirated bilabial plosives: /p/ versus /pp/, as present in Italian. For half of the speakers, auditory feedback was completely blocked during training. Results indicate that although there is no immediate effect when auditory feedback is masked, deviating productions emerge during the course of learning. By the end of training, speakers with masked feedback produce strong lengthening of segments and show more variation in their production than speakers with auditory feedback. These results provide evidence that auditory feedback is necessary for the learning of precise coordination of articulation, and that even aspects of speech which are salient in somatosensory terms are monitored auditorily during the learning of a new speech sound contrast.
The effect of word segmental structure on consonant length categorization by Finnish speakers.
Authors: Yoshida Kenji , de Jong Kenneth , Paivio Pia-Maria
Published: October 2009

While both Finnish and Japanese have a contrast in segmental length, previous research [Aoyama (2000)] has found that Finnish listeners exhibit a sharper identification for consonant length contrasts. The present study examines the effect of segmental structure on length categorization in the two languages. Twenty-two Finnish speakers were presented acoustic stimuli, where silence intervals with the duration of seven equal steps were embedded in three pairs of nonsense words spoken by a Finnish and a Japanese speaker and gave forced choice responses between single and geminate. The result shows that the slope of the identification function is steeper for the stimuli produced by the Finnish talker. Moreover, the study finds earlier identification with geminate for the words with CVC initial syllable as compared to CV. This effect of segmental structure, however, is restricted when the target consonant is located in the third syllable and for the stimuli produced by the Finnish speaker. These observations suggest that the listeners refer to their knowledge that the vowel in the second syllable is longer when preceded by CV syllable, the phonetic fact known as “half-long vowel” in Finnish [Suomi et al. (2003)]. [Work supported by Finlandia Foundation National Scholarship.]
Autistic traits predict individual differences in speech categorization.
Authors: Hufnagle Dan , Holt Lori L. , Thiessen Erik D.
Published: October 2009

Investigating individual differences in speech perception using measures of “autistic” traits in neurotypicals can gauge natural variability in speech processing [M. Stewart and M. Ota, Cognition 109, 157–162 (2008)]. Using the autism-spectrum quotient (AQ) [Baron-Cohen et al., J. Autism & Dev. Disord. 31, 5–25 (2001)], which measures autistic traits in neurotypicals, we investigated individual differences in context-dependent speech processing. Twenty-eight neurotypicals categorized a nine-step da/ga series in the context of non-speech tone precursors [following L. Holt, Psychol. Sci. 16, 305–312 (2005)] and completed the AQ. Context included three tone groups, including relatively high (shift toward ga), medium, and low (shift toward da) tones. Overall, the temporally adjacent tone grouping shifted perception more than distant context (p<0.001). Effects correlated with AQ (r=0.53). Lower AQ (fewer autistic traits) is associated with near-zero context dependence for endpoint categorization and large context-dependence for ambiguous speech-target categorization. Higher AQ is associated with intermediate influence of context across the series. Individual differences in context-dependent phonetic processing can be predicted from a personality trait scale, suggesting that phonetic processing is not immune from the influence of higher-order cognitive processes associated with these traits or that lower-level perceptual processing varies with these traits. [Work supported by NIH.]
Identification of asynchronous monaural and dichotic vowel pairs across the adult lifespan.
Authors: Fogerty Daniel , Kewley-Port Diane , Humes Larry
Published: October 2009

Temporal onset asynchrony is one cue that listeners use to identify concurrent vowels. Young (N=80; 18–31 years), middle-age (N=40; 40–55 years), and older (N=150; 60–88 years) adults identified vowel pairs in a temporal-order paradigm under monaural and dichotic stimulus presentations. Experiments used forced-choice constant-stimuli methods to determine the smallest stimulus onset asynchrony (SOA) between brief 70-ms vowels that enabled identification of the stimulus sequence. Vowels modified from four words (pit, pet, pot, and put) served as stimuli. All listeners identified the vowels in isolation with better than 90% accuracy. Results indicated that older listeners performed significantly poorer on monaural and dichotic temporal-order identification tasks than young listeners, with middle-age listeners in between. Correlations of performance with age across the full age span were moderate. For all three groups, SOAs for the dichotic task were significantly longer than those for the monaural task. A significant main effect of vowel pair was observed, indicating that not all vowel pairs were equally identifiable. Patterns of vowel pair identification were similar across all groups for both monaural and dichotic presentations; however, interactions with age group were observed. Effects of vowel order and dominance were also observed. [Work supported, in part, by NIA R01 AG022334.]
Effect of frequency selectivity on the perception of spectrally/temporally interrupted speech.
Authors: Hsieh Michelle , Jin Su-Hyun
Published: October 2009

Compared to normal hearing (NH), hearing impaired (HI) listeners have shown significantly less masking release, even when the speech and noise were amplified to compensate for their hearing loss [J. Nelson (2004)]. According to Jin (2003), the reduced masking release of HI listeners was highly related to auditory filter bandwidths, which is an indicator of frequency selectivity. As a follow-up, the present study examined whether the reduced frequency selectivity might influence on spectrally-based perceptual strategies for speech recognition of NH and HI listeners in complex noise. We hypothesized that even with mild hearing loss, HI listeners would show significantly different spectral weight which would be significantly correlated with individual’s hearing loss. In this study, signal processing was carried out in the digital domain and involved splitting of the signal spectra into five frequency bands for both speech and noise (band 1: 100–250 Hz, band 2: 250–750 Hz, band 3: 750–1750 Hz, band 4: 1750–3750 Hz, and band 5: 3750–7750 Hz). The subject’s task was to identify the sentences heard in quiet, steady, and fluctuating noise in each band. The hypothesis will be examined and its implication on speech perception of HI listeners and signal processing strategy for the amplification system.
Competition among variant word forms in spoken word recognition.
Authors: Geer Micah
Published: October 2009

Words in casual speech exhibit considerable variation in articulation. For example, alveolar stop consonants (/t/ and /d/) in certain phonetic environments may be realized as taps, glottal stops, careful /t/s and /d/s, or they may be deleted altogether. Thus, words containing non-word-initial alveolar stops may be represented in memory as multiple specific variants. Whether these multiple representations of variant forms compete for recognition, and at what level of representation such competition might occur, was investigated. Processing time was measured for monosyllabic words ending in either alveolar or non-alveolar (bilabial or velar) stops. Alveolar-ending words were responded to more slowly than carefully matched non-alveolar ending words in both lexical decision and same-different matching tasks. This result did not hold for similarly composed nonwords. In a follow-up experiment, the proportion of alveolar-ending neighbors in a word’s phonological neighborhood was manipulated. Overall, the results suggest that variant word forms compete at a stage beyond sublexical processing. Implications for characterizing competition in spoken word recognition are discussed.
Integration of phonological information in obstruent consonant identification.
Authors: Silbert Noah H. , de Jong Kenneth J. , Lentz Jennifer J. , Townsend James T.
Published: October 2009

Speech perception requires the integration of information from multiple phonetic and phonological dimensions. Numerous studies have investigated the mapping between multiple acoustic-phonetic dimensions and single phonological dimensions (e.g., spectral and temporal properties of stop consonants in voicing contrasts). Many fewer studies have addressed relationships between phonological dimensions. Most such studies have focused on the perception of sequences of phones (e.g., bid, bed, bit, and bet), though some have focused on multiple phonological dimensions within phones (e.g., voicing and place of articulation in [p], [b], [t], and [d]). However, strong assumptions about relevant acoustic-phonetic dimensions and/or the nature of perceptual and decisional information integration limit previous findings in important ways. New methodological developments in the general recognition theory framework enable a number of these assumptions to be tested and provide a more complete model of distinct perceptual and decisional processes in speech sound identification. A non-parametric Bayesian analysis of syllable-onset consonant identification data from two experiments indicate that integration of phonological information is partially independent of both perception and decision making for most subjects, and that patterns of independence and interaction vary with the set of phonological dimensions under consideration (e.g., voicing and place of articulation versus voicing and manner of articulation).
Interaction of top-down and bottom-up processing on categorical perception.
Authors: Lee Ji Young , Hedrick Mark
Published: October 2009

To investigate the processing of acoustic and semantic information on phonemic categorical perception, two nine-step continua consisting of natural and synthetic consonant-vowel (CV) syllables were presented in four different contexts. For both natural and synthetic speech, /ti/-/pi/ continua varying in spectral tilt were constructed. The four contexts included the isolated CV syllable, a neutral context sentence with the CV at the end, and two additional sentences with varying semantic load. One semantically favored a /p/ response and one a /t/ response. Eleven adults with normal hearing (2 males, 9 females, 21 45 years old, mean age=27) labeled the consonant in the CV syllable. Results showed a pattern of statistically-significant differences between the isolated and neutral context versus the semantically-loaded sentences for both natural and synthetic stimuli, suggesting an effect of semantic context. The differences appeared in the vicinity of the boundaries of the psychometric functions, suggesting an interaction between top-down and bottom-up processing. Strictly bottom-up processing would have shown overlaid response functions, and strictly top-down processing would have shown differences at the endpoints. The pattern of results suggests interactive, parallel rather than hierarchical processing.
The influence of talker gender, formant-frequency scaling, and presumed sources of variance on the perception of voiceless fricatives in American English.
Authors: Munson Benjamin , Coyne Alexander
Published: October 2009

We examined listeners’ identification of sigh-shy and sigh-thigh stimuli created by appending /s/-/∫/ and /s/-/θ/ continua to tokens of /ɑɪ/ excised from the natural productions of sigh spoken by one man and one woman. The values of the formants for the vocalic bases were scaled to give the illusion of differences in talkers’ overall stature. Five levels of scaling were created for both the man and woman’s productions. For the /s/-/∫/ continuum, listeners perceived more /∫/ with women’s voices than with men’s voices but, contrary to earlier research, showed gradient effects of formant scaling on phoneme boundaries for both the male and female tokens. For the /s/-/θ/ continuum, more /s/ tokens were identified for women’s voices than for men’s voices. Gradient effects of formant-frequency scaling were found for both men’s and women’s voices, and these were much smaller than those for /s/-/∫/. Listeners who were led to believe that the scaling reflected differences in talkers’ age height showed a bigger influence of scaling on /s/-/θ/ perception than did listeners who were told they reflected differences in height. Together, these results show that perceived gender, vocal-tract normalization, and social stereotypes influence fricative identification.
Examining the role of pitch, duration, and intensity in word segmentation.
Authors: Vicenik Chad
Published: October 2009

English listeners can make use of stress cues in word segmentation. Stress is associated with a number of phonetic cues, including pitch movements, longer durations, and greater intensity. Studies on stress perception have shown that pitch is the most powerful cue to English stress, followed by increased duration and greater intensity [Fry (1958); Bolinger (1958)], suggesting that pitch alone might be sufficient to cue word boundary. Here, I test whether pitch alone is enough to cue word boundary for English listeners, using an artificial language paradigm. The artificial language used contains no distributional cues to word boundary, so words can only be segmented using pitch. I also pit pitch cues against intensity and durational cues in order to test whether English listeners weight cues for stress in a word segmentation task, or if they require correlates of stress to be bundled together.
Lexicalizing nonadjacent dependencies.
Authors: Berg Steven A.
Published: October 2009

Previous research [e.g., McLennan et al. (submitted)] has demonstrated that listeners are sensitive to discontinuous dependencies among consonants, vowels, and syllables in nonsense words. An extension of this work was done by attempting to lexicalize nonwords containing discontinuous dependencies through a referent matching paradigm. Our attempt at lexicalization was to determine the consequences of discontinuous dependencies at the lexical rather than sublexical levels. Our findings are discussed in terms of sublexical and lexical effects of phonotactics in spoken word recognition.
Maximum entropy inference method applied to shallow-water ocean waveguides.
Authors: Sagers Jason D. , Knobles David P.
Published: October 2009

The principle of maximum entropy (MaxEnt) is used to analyze the uncertainty that is associated with determining geo-acoustic waveguide parameters for shallow-water ocean environments. Marginal probability distributions and statistics, such as the mean and standard deviation, for each geo-acoustic parameter are obtained using MaxEnt methods. Both theoretical and numerical components of the MaxEnt method are addressed. The method is applied to experimental acoustic measurements taken on the New Jersey continental shelf on a sand ridge where a priori information includes sound velocity measurements in the water column and chirp seismic reflection grams that provide geophysical ground truth on the seabed layering structure. The acoustic data used in the geo-acoustic inference result from a towed multi-frequency source. The effect of discretization choices for the geo-acoustic representation on the marginal probability distributions is investigated. The effect of changing a priori information (such as the assumed sound velocity profile in the water column) on the marginal probability distributions of the geo-acoustic parameters is also explored.
Observation and modeling of sound propagation through a dynamic ocean on the continental shelf of the northeastern South China Sea.
Authors: Chiu Ching-Sang , Miller Christopher W. , Chen Chi-Fang , Chiu Linus , Wei Ruey-Chang
Published: October 2009

In April 2005, a 3-day acoustic transmission experiment was carried out on the shelf of the northeastern South China Sea. A 400-Hz signal was transmitted every 5 min from a moored source to a moored vertical hydrophone array 17 km away. Additionally, a series of oceanographic moorings was deployed along the transmission path to sample the water-column variability that was dominated by the evolution of nonlinear internal tides and high-frequency nonlinear internal waves. Applying time-series filtering, principal component analysis, and a feature tracking technique to the oceanographic data, a continuous space-time empirical model for the sound-speed field was developed. Using a coupled-mode sound propagation model, interfacing with the sound-speed model, the temporal variations of the vertical distribution of signal intensity at the hydrophone array were computed. Analyzing the model results and comparing them to the measured signal intensities have allowed for quantification and comparison of the effects of the nonlinear internal tides, depression waves, and elevation waves on the sound transmission. The modeled sound-speed and sound-intensity fields and their comparisons to the measured data are discussed in this paper. [This research is jointly sponsored by the U.S. Office of Naval Research and the Taiwan National Research Council.]
Across-shelf versus along-shelf coherence length estimates of low-frequency pulse transmissions on the New Jersey continental shelf.
Authors: Collis Jon M. , Duda Timothy F. , Lynch James F. , DeFerrari Harry A.
Published: October 2009

Sound at 100–400 Hz propagating in approximately 80-m depth water from fixed sources to a joint horizontal/vertical line array (HVLA) is analyzed. The data are from an area east of Delaware Bay in the Mid-Atlantic Bight populated with tidally-generated long- and short-wavelength internal waves that propagate generally shoreward. Two paths are used: a 29-km path in the cross-shore (across internal wave crest) direction and a 19-km path in the along-shore direction. Spatial fluctuations of HLA arrivals have been computed as a function of HLA beam steering angle and time: array gain, horizontally lagged field coherence function, and coherent beam power. These quantities and fitted characteristic coherence scale lengths vary in apparent response to internal-wave variability [Collis et al., J. Acoust. Soc. Am. 124, EL97 (2008)]. In this presentation, coherence length estimates are provided for the month of August 2006. In additional to internal volume effects, consideration is given to signal duration, angle of incidence, and along-shelf versus across-shelf propagation. [Work supported by the Office of Naval Research.]
Use of acoustic frequency shifts for monitoring oceanographic processes in shallow water.
Authors: Turgut Altan
Published: October 2009

Waveguide invariant theory is used to calculate the frequency shifts of the acoustic intensity spectral levels caused by environmental variability in shallow water. In winter conditions, long-term acoustic monitoring of tide and slope water intrusions has been demonstrated using measured frequency shifts of the acoustic intensity spectral levels [Turgut et al., J. Acoust. Soc. Am. 121, 2534–2541 (2007)]. Acoustic frequency shifts caused by other oceanographic processes such as background internal waves and solitary internal waves are also investigated. Additional broadband acoustic data from several summer experiments indicate the feasibility of extracting background internal wave parameters as well as internal solitary wave parameters when they propagate almost perpendicular to the acoustic propagation path. [This work was supported by the ONR.]
The effect of time resolution (bandwidth) on clutter statistics: A vertical echo sounder as a simple test case.
Authors: Harrison Chris
Published: October 2009

The scintillation index (SI) of sonar returns from a rough seabed was recently simulated using a Kirchhoff approach both numerically and semi-analytically [C. Harrison, J. Acoust. Soc. Am. 125, 2661 (2009); IEEE JOE. In press]. Of particular interest was the potentially high SI associated with seabed reflection focusing. In carrying out this kind of numerical investigation, one needs to be very careful of what precisely constitutes the ensemble. Here we perform the same analysis but now with a finite pulse length. At sufficient altitude, the tail of the pulse may contain contributions from many different almost specular facets. Depending on the sonar’s time resolution these may, or may not, be seen as many intersecting echoes. Even with a pulse length long enough to incorporate the vertical extent of the roughness, it is possible to find sharp spikes in the echo tails. Thus a plot of Si versus travel time (the ensemble being ping-to-ping variation) has a peak more than one pulse length after the main arrival. Amongst other things, this makes it clear that SI is highly dependent on time resolution and furthermore may be more a function of the observing system than the object being observed.
A soundscape pons asinorum: Interim adaptation of A-weighted measurement practices to foster more accurate assessments of noise impacts in protected natural areas.
Authors: Fristrup Kurt M.
Published: October 2009

A-weighted measurements of environmental sound levels in functional ecosystems are often elevated by natural sources of sound energy above 1 kHz. It is aesthetically and biologically questionable to assert that a rich chorus of bird, frog, and insect sounds renders an environment less vulnerable to the effects of noise confined to lower frequencies. Accordingly, it seems worthwhile to explore alternative approaches to computing A-weighted sound levels that would reduce or eliminate this source of inflated measurements in park and wilderness settings. A systematic evaluation of acoustical measurements in units of the U.S. National Park Service reveals the extent to which A-weighted values are influenced by environmental sounds in each 1/3 octave band. This analysis can help motivate and inform the development of revised standards for A-weighted noise measurement and evaluation in protected natural areas. This seems a plausible first step toward a more biologically rigorous framework for assessing the impacts of noise to wildlife and visitors in National Parks.
Comparison of sound pressure levels of mid-to large size on-road motorcycles through volume modeling.
Authors: Neale William T. C. , Terpstra Toby
Published: October 2009

Noise from motorcycles varies between make and model, style, and engine size. The motorcycle’s pipe design, materials, and gearing are just a few of the factors that determine the noise being emitted. In regular traffic situations, though, an observers relative position to the motorcycle varies, and this change in position greatly affects the experience of motorcycle noise. This paper examines how noise level differs depending on ones location to a motorcycle by mapping the sound pressure level of various styles and designs of motorcycles three dimensionally. Specifically, decibel levels and frequency spectra are measured volumetrically around the motorcycle to create a three dimensional map for each motorcycle. These three dimension sound maps are then compared and evaluated for patterns of direction bias, maximum sound level, and frequency.
A method for direct impedance measurements in long range propagation of low-frequency sound.
Authors: So Jin H. , Talmadge Carrick L. , Waxler Roger , Gilbert Kenneth E.
Published: October 2009

A method for direct impedance measurements in long range propagation of sound, significantly below 200 Hz, is presented. The linear least-squares fit to the measured pressure data, as a function of the sensor height, the so called “pressure derivative method,” was utilized to obtain the pressure derivatives. Several sensors were installed vertically on the array above the ground. The ground was a flat agricultural farm. The propagation distance of sound over the ground was 0.41 km. Sound sources included pulses and pure tones. The impedances for the pulses and tones showed good agreement. Overall, the imaginary components of the impedance were much larger than the corresponding real components in the frequency range studied.
Analysis of the environmental effects on the ringtone volume.
Authors: Kim Cheol Hong , Choi Hong Jun , Kim Jong-Myon
Published: October 2009

Due to the wide spread of mobile phones, the use of them in public space keeps increasing. Thanks to their advantageous features, mobile phones enable people to feel convenience in making a call. However, the use of mobile phones in public space is blamed for causing others’ inconvenience due to reckless noisy ringtones, especially in the quiet places such as classroom and conference room. In this work, we analyze the environmental (temperature, humidity, ambient noise, and vibration) effects on the ringtone volume to reduce the noise in public space. In fact, many users put their mobile phones in silent or vibrate mode in public space. However, we can still hear ringtones occasionally in public space. Therefore, if ringtones can be automatically adjusted to the appropriate volume level by considering the environmental effects, it can be very helpful to mobile phone users. To find the appropriate volume level, we analyze the various environmental effects by conducting actual experiments. According to our experimental results, vibration and ambient noise have strong relation with the ringtone volume, whereas temperature and humidity show little correspondence on the ringtone volume. [Work supported by the MKE, Korea, under the ITRC supervised by the IITA [IITA-2009-(C1090-0903-0008)].]
Influence of viscoelasticity on the ultrasonic wave propagation in cortical bone: Application to the axial transmission technique.
Authors: Haiat Guillaume , Naili Salah , Vu Mai-Ba , Grimal Quentin , Talmant Maryline , Desceliers Christophe , Soize Christian
Published: October 2009

Cortical bone quality is assessed in clinical practice using axial transmission (AT) devices. Cortical bone and the surrounding soft tissues are attenuating media, which might affect the results obtained with AT devices. Following the work of in Haiat et al. [J. Acoust. Soc. Am. (2009)] which considers the elastic case, the aim of this work is to evaluate the effect of anisotropic heterogeneous dissipative phenomena occurring in bone and in soft tissues on the ultrasonic response of the bone structure. A two-dimensional finite element time-domain method is derived to model transient wave propagation in a three-layer medium composed of an inhomogeneous transverse isotropic viscoelastic (Kelvin–Voigt description) solid layer sandwiched between two dissipative acoustic fluid layers. Bone viscoelasticity is assumed to be heterogeneous and a constant spatial gradient of viscoelastic properties is considered for two values of bone thicknesses corresponding to relatively thick and thin bones. The results allow the derivation of a contributing depth (CD) for a thick bone width. For a gradient of viscoelasticity, CD≅1.6 mm, for a gradient of C11, CD≅0.6 mm, and for a gradient of mass density, CD≅1 mm. [The Agence Nationale de la Recherche (Contract No. no BLAN06-2 144779) is acknowledged.]
How does sound leave the cochlea?
Authors: Li Yizeng , Grosh Karl
Published: October 2009

In normal operation, sounds enter the cochlea via the stapes and generate forward traveling waves on the fluid-loaded basilar membrane [e.g., Bekesy (McGraw-Hill, 1960)]. Kemp [J. Acoust. Soc. Am. 64 discovered that sound is emitted by the cochlea in a way that is physiologically vulnerable. These sounds are called otoacoustic emissions (OAEs). Because of their relation to the health of the cochlea, OAEs have evolved as a tool for both noninvasive diagnosis and understanding cochlear mechanics [Probst, J. Acoust. Soc. Am. 89]. However, OAEs are not yet completely understood. OAEs are hypothesized to arise from active processes in the cochlea. The path that intracochlearly generated sound takes when emitted from the cochlea—as a slow coupled fluid-structure wave or a fast mainly fluid borne wave (Wilson, Phys. Today (2008)]—has yet to be established. This work uses animations of mechanical-electrical-acoustic finite element model transient response predictions due to internal excitation of the basilar membrane to study the path of propagation. Models of sensitive and insensitive cochlea are used to determine the effect of sound level and cochlear health.
Rayleigh–Lamb wave propagation on a fractional order viscoelastic plate.
Authors: Meral Faik C. , Royston Thomas J. , Magin Richard L.
Published: October 2009

Previous studies of the authors published in JASA focused on shear and surface wave motion in and on a viscoelastic material representative of biological tissue. Specific cases considered were that of surface wave motion on a half-space caused by a finite rigid circular disk located on the surface and oscillating normal to it and compression, and shear and surface wave motion in a half-space generated by a subsurface finite dipole. In both situations, recently it has been shown that viscoelasticity models based on fractional order derivatives result in closer agreement with experiment as compared to conventional models, such as those of Voigt and Zener. In the present study, this comparative analysis is extended to another configuration and wave-type, that of out-of-plane response of a circular viscoelastic plate to harmonic anti-symmetric excitation. The Rayleigh–Lamb equation is solved using complex wave numbers based on conventional and fractional order viscoelastic models for the medium. The new theoretical solutions are compared with experimental measurements. The underlying physical motivation for the use of a fractional viscoelastic assumption and the potential practical benefits, such as improved medical diagnostics, are discussed. [Work supported by NIH Grants EB004885, EB008373, and EB007537.]
The effect of short-term training on production and perception of s/∫ by Korean speakers.
Authors: Fox Robert Allen , Jacewicz Ewa , Eckman Fred R. , Iverson Gregory K. , Lee Soyoung
Published: October 2009

This study examines the efficacy of short-term training on learning the English s/∫distinction by native speakers of Korean. The production and perception of Korean L2 learners was tested before and after a short computer-controlled training session. Of interest in this study is to determine which acoustic characteristics of these fricatives (if any) improve after a focused training session, whether English listeners perceive them more “English-like,” and whether the L2 learners can more accurately identify these fricatives after training. Korean speakers were initially recorded producing common English words containing these two fricatives in initial, medial, and final positions. Each speaker then underwent focused training on the s/∫distinction in a small set of nonsense words. Training ended when speakers met an established performance criterion. In a post-test, speakers were again recorded producing the same words. Acoustic measurements (including duration, relative amplitude, spectral mean, variance, skewness, and kurtosis) were obtained for each fricative from both sets of recordings and from productions by native English speakers. Perception data (including both identification and discrimination) were also obtained from the English-speaking controls and from L2 speakers both before and after the training. Results will be discussed in light of universal principles of language acquisition.
The correlation between perceiving and producing English obstruents across Korean learners.
Authors: de Jong Kenneth , Hao Yen-chen
Published: October 2009

Our previous work determined that the skill structure evident in cross-subject correlations differed in second language production and perception. This study examines how these production and perception skills correlate across subjects, finding pervasive differences between contrasts similar to ones in the L1 and novel contrasts. Twenty Korean learners of English listened to and identified eight anterior obstruents produced by four American English speakers before, after, and between the vowel /a/. The same learners were also presented with orthographic probes and produced the same eight obstruents, and English listeners identified the consonants in these recordings. Analyses show no significant correlations between production and perception accuracy in consonant voicing (similar to L1), indicating pervasive disjunction between perceiving and producing voicing contrasts in the learners. Voicing accuracy was systematically better in identification than production, suggesting a precedence for perceptual learning. Analyses of manner accuracy in labial consonants, however, reveal a robust correlation, indicating a strong relationship between perceiving manner contrasts (novel to L1) and producing them. In addition, several subjects exhibited better accuracy in production than perception, suggesting an interaction of perceptual and motor learning. Coronal stops and fricatives show similar patterns, however, without the robust correlation between perceptual and production accuracy.
Production and perception of English /l/ and /r/ by native-speaking children.
Authors: Idemaru Kaori , Holt Lori L.
Published: October 2009

The English /l-r/ distinction is a difficult contrast to learn for L2 learners as well as for native speaking children. In this study, we examine the use of the second (F2) and third (F3) formants and the relative weighting of these cues in production and perception of /l/ and /r/ sounds in native-English-speaking children. 3-, 4-, 5-, and 8-yr-old children produced words including /l-r/ and they were also tested for identification of words including the contrast. The results indicated that whereas young children’s productions of /l/s and /r/s were well distinguished acoustically, the children were still developing in how they integrate F3 and F2 in both production and perception. Specifically, children’s production indicated an intriguing developmental change such that F2 frequency increased in older children’s /r/ productions, thus diminishing the F2-F3 frequency difference across development. In perception, although a sharper pattern of perception of the contrast was found in older children, they were not using F2 (a secondary cue signaling the categories) in the same manner as adults even at age 8. These data are consistent with a rather long trajectory of phonetic development whereby native categories are refined and tuned well into childhood [Work supported by NSF Grant No. BCS-0746067].
A longitudinal study of English and Japanese vowel production by Japanese adults and children in an English immersion setting.
Authors: Oh Grace , Guion Susan G. , Flege James E. , Aoyama Katsura , Akahane-Yamada Reiko , Yamada Tsuneo
Published: October 2009

The effect of age of acquisition on first- and second-language vowel production was investigated. Eight English vowels were produced three times in two different words each by 16 native Japanese (NJ) adults and children as well as 16 age-matched native English (NE) speaking adults. Productions were recorded shortly after the NJ participants’ arrival in the United States and then 1 year later. In agreement with previous investigations [Aoyama et al., J. Phonetics 32, 233–250 (2004)], children were able to learn faster, leading to higher accuracy than adults in a year’s time. Based on acoustic measurements, NJ adults had more accurate production at Time 1 but made no changes across time. The NJ children, on the other hand, showed significant differences from NE children’s productions for /ɪ/, /ε/, /ɑ/, /ʌ/, and /U/ at Time 1, but produced all eight vowels in a native-like manner at Time 2. A follow up examination of NJ children’s productions of Japanese /i/, /a/, /u/ revealed significant changes for Japanese /i/ and /a/ related to L2 learning. The results suggest that L2 vowel production is heavily affected by age of acquisition and that there is a dynamic interaction between first- and second-language vowels. [Work supported by NIH.]
Native language phonetic drift in beginning second language acquisition.
Authors: Chang Charles B.
Published: October 2009

Mounting evidence has shown that native language (L1) phonetic representations can be affected by extensive second language (L2) learning. In this study the nature and time course of this phonetic drift in L1 are examined in a longitudinal investigation of 20 L1 English speakers’ first 5 weeks of learning Korean as L2. Acoustic analyses of these learners’ L1 and L2 speech production over time show that learning L2 stops affects the production of L1 stops (in terms of VOT and/or f0 onset) in as little as 1 week, with the L1 sounds approximating the L2 sounds to which they are most phonetically similar. English voiced stops do not change significantly in VOT over time, since they are already similar to Korean fortis stops in this respect; however, they rise in f0 onset in approximation to the elevated f0 onset typical of Korean fortis stops. Meanwhile, English voiceless stops become longer in VOT and higher in f0 onset in approximation to the Korean aspirated stops. These results indicate that L1 phonological categories are affected by L2 learning on a very short timescale, suggesting that the L1-L2 equivalence classification that gives rise to this phonetic drift may be rather low-level in nature.
Do they read aloud in a different way? A glimpse on the prosodic features of corpus-based second language spoken English.
Authors: Chen Sally , Fon Janice , Cheung Hintat
Published: October 2009

This study investigated the prosodic features of L2 spoken English. A set of ten recordings was extracted from an in-progress learner corpus on an English proficiency test. Each recording consists of two passages as read aloud by a learner who had received a grade of 3, the median grade of the test, on a five-point scale. A group of ten native English speakers was recruited to serve as controls. They were given the same test materials and their readings recorded under a test scenario similar to that of the L2 learners. The labeling followed the English ToBI convention. Preliminary results showed that in general, the L2 learners addressed more tones in their production. In terms of break indices, the L2 utterances were consistently segmented into a larger number of intonational units, as compared to those of the native speakers. In addition, silence was frequently employed in the L2 word-level boundaries to facilitate enunciation, explained in that English has a more complex phonotactic structure than their native tongue, Mandarin. Finally, the L2 data exhibited more varied pitch accent types than the native-speaker data, which corresponds to the findings of our previous study regarding an L2 read-aloud task on simple English sentences.
Comparison of perceptual vowel space for native vowels for monolingual and bilingual speakers of Malayalam.
Authors: Radhakrishnan Sreedivya , Hawks John W.
Published: October 2009

This study examines the perceptual vowel space for Malayalam for monolingual and bilingual Malayalam speakers. Malayalam is the native language of the state of Kerala, India, which uses five long and short vowels. Hence, in addition to spectral differences, speakers of Malayalam may use duration for the identification of vowels. This is different from English, which uses predominantly spectral differences alone as the major cue for vowel identification, even though there are intrinsic differences in duration for the English tense/lax vowels. There were two groups of subjects, native speakers of Malayalam and speakers of Malayalam who have also been speaking English for at least 10 years, with ten subjects in each group. The stimuli consisted of synthetic tokens of isolated vowels, which varied in first, second, and third formant frequencies. An identification task, followed by rating task, was carried out. This study maps the perceptual vowel space of native Malayalam speakers and also addresses a less widely studied area of cross-language speech perception, i.e., the influence of second language on the perception of the native language. Thus, the results provide a basis for the examination of the influence of long-term use of English on the perception of native Malayalam vowels.