bluuebunny/crossref_metadata_2025 huggingface dataset:
Children’s control of temporal variability in repetition tasks
Authors: Smith Bruce L. , Kenney Mary Kay
Published: October 2005

Although several previous studies of normally developing children have examined effects of speaking rate changes on segment duration and variability and their possible relationship to neuromotoric maturity for speech, there have been no investigations concerned with children’s ability to directly control the variability of their speech. The present study attempted to evaluate children’s control of temporal variability by assessing the performance of 7- to 11-year-old subjects who were asked to minimize variability in their speech. The tasks included: (1) a control condition, in which 11 subjects repeated a variety of stimuli 25 times each, with no special instructions as to how they were supposed to produce them, and (2) an experimental task, in which subjects were specifically instructed to be as consistent as possible in repeating stimuli in an attempt to minimize variability. Results indicate that for the group as a whole, the temporal variability of various speech segments did not tend to differ substantially when comparing the children’s control and experimental productions, with approximately half the subjects showing small decreases in variability and half showing small increases for the segments that were measured. It, thus, appears that for at least this type of repetition task, subjects perform at essentially optimal levels, in terms of variability, even when not specifically attempting to do so.
Syllable duration in Italian and Japanese
Authors: Brighenti Laura , Homel Peter
Published: October 2005

This study analyzes duration of stop syllables in Italian and Japanese. Its results show that the two languages are very similar in terms of syllable length. They also indicate that, in accordance with previous findings, both Italian and Japanese syllable duration is contrastive in terms of gemination, and Italian duration is also contrastive as a function of stress. Finally, they show that both languages present variability in the duration of their syllables, even in cases where the syllable is neither geminate nor stressed. These results point to the following conclusions: (1) other elements outside the syllable itself (i.e., position within word, surrounding syllables, information content, etc.) may be involved in determining syllable duration; and (2) the stress-timed/syllable-timed language distinction may not be useful for understanding how languages assign duration for particular parts of the syllable. In particular, the results of this study indicate that stress and syllable position play an important role in determining syllable duration even in syllable-timed languages.
Lexical effects in nonwords?
Authors: Newman Rochelle , Sawusch James R. , Luce Paul
Published: October 2005

Previous research has reported the existence of a ‘‘lexical effect’’ in identification tasks. For instance, one series might range from ‘‘dice’’ to ‘‘tice,’’ while the other varied from ‘‘dype’’ to ‘‘type.’’ The ambiguous stimuli from each series were more likely to be classified as members of the category which makes a word. (Thus, they would be classified as ‘‘d’’ in the dice-tice series but as ‘‘t’’ in the dype–type series.) However, these results have sometimes been inconsistent, suggesting that factors other than lexical status are involved. In a series of experiments, pairs of nonword–nonword continua were presented to listeners, where one end of each series had a higher neighborhood density than the other end. That is, one end of each series was similar to a greater number of words, weighted according to frequency of occurrence, than the other. Ambiguous items were classified by listeners with the phonetic label corresponding to the higher density end of the series. The results suggest that neighborhood effects may contribute to the variability in previous ‘‘lexical’’ effects. [Supported by NIDCD Grant No. DC00219 to SUNY at Buffalo and an NSF Graduate Fellowship to the first author.]
Transformed auditory feedback: Effects of fundamental frequency perturbation
Authors: Kawahara Hideki
Published: October 2005

A rapid interaction between auditory perception and speech production has been found using the technique of transformed auditory feedback with fundamental frequency perturbation as the transformation. The technique of transformed auditory feedback has been developed to investigate the role of auditory perception in speech production under natural conditions. The basic idea of the method is to keep the disturbance of normal speech production processes to a minimum, while allowing interactions between speech production and auditory perception to be detectable. In the first experiment, subjects were instructed to sustain the Japanese vowel /a/ with a constant pitch. The phonated vowel was frequency modulated using sinusoids of 2- to 7-Hz range and fedback diotically via headphones. The modulation depth was 200 cent from peak to peak. The results indicate that there is a phase-locking effect in the fundamental frequency of the produced speech. In a second experiment, a correlation analysis using a pseudo-random signal as a modulator revealed that the reaction to fundamental frequency perturbation is corrective and that its latency ranges from 100 to 200 ms. Its relation with the auditory-laryngeal reflex will be discussed.
Modeling acoustic particle velocity in range-dependent environments with a parabolic equation code
Authors: Smith K. B. , D’Spain G. L. , Hodgkiss W. S.
Published: October 2005

Measurements have been made of the acoustic particle velocity field generated by a towed source transmitting 7-, 10-, and 16-Hz tones. The periodic change in the polarization of the motion as a function of source–receiver range, from prograde circular motion to retrograde circular motion and back, appears to have been disrupted by changes in slope of the bottom topographic features in the experiment. In order to test this hypothesis, the University of Miami parabolic equation code (UMPE) was modified in order to efficiently calculate acoustic particle velocity. This numerical code makes effective use of the equivalent fluid approximation for low shear speed ocean bottoms [C. T. Tindle and Z. Y. Zhang, J. Acoust. Soc. Am. 91, 3248–3256 (1992)]. The predictions of the UMPE model are compared with the actual measurements, and with the predictions made by the finite element parabolic equation (FEPE) by M. D. Collins, which explicitly incorporates the effects of bottom shear. [Work supported by ONR.]
Long-range acoustic propagation in four dimensions
Authors: Orris Gregory J. , Collins Michael D.
Published: October 2005

Ocean acoustic modeling is usually restricted to frequency-domain problems in two dimensions. Since ocean acoustics problems typically involve domains that are very large relative to a wavelength, computation times often become prohibitive when a third dimension (either time or the third spatial variable) is included. The adiabatic mode parabolic equation (PE), which has been applied to solve global-scale problems in three spatial dimensions [Collins etal., J. Acoust. Soc. Am. 93, 2321 (1993)], is practical for solving four-dimensional problems out to long range (i.e., hundreds of wavelengths or more). In the time domain, the adiabatic mode PE solution illustrates the flow of energy in the modal coefficients, which depend on range and azimuth.
Release-from-masking effects provided by a hearing aid digital signal processor
Authors: Grim Michael A. , Schwietzer Christopher , Lindemann Eric , Sweetman Richard H.
Published: October 2005

Release-from-masking effects provided by a digital hearing aid signal processor utilizing multiple-microphone inputs were evaluated with three measures of speech recognition. Speech recognition measures were monosyllabic word recognition score, reaction time, and subjective rating of the intelligibility of selected passages of continuous discourse. Microphones, placed on KEMAR, recorded speech stimuli embedded in cafeteria noise yielding S/N ratios of 0 and 8 dB SPL. Half of the speech-in-noise stimuli were processed through the hearing aid digital signal processor while half remained unprocessed. The hearing aid processor utilizes a technology similar to adaptive-beamforming to reduce the masking effects of background noise on speech recognition. Unprocessed and processed speech-in-noise stimuli were presented to 10 normally hearing subjects, 10 hearing-impaired subjects, and 10 hearing-impaired individuals fit with linear amplification. Comparison of word recognition scores, reaction times, and intelligibility ratings for the two S/N ratios between unprocessed and processed speech-in-noise stimuli suggest that the hearing aid processing scheme provides significant release-from-masking effects which may improve the recognition of speech in noise for normally hearing and hearing-impaired listeners.
New algorithm for calculating normal modes in broadband applications
Authors: Koch Robert A. , Knobles D. P.
Published: October 2005

A new algorithm for calculating the normal modes that are used to describe underwater acoustic propagation is presented. The algorithm is especially relevant for broadband normal mode calculations in which normal mode eigenvalues, depth functions, and attenuations are needed. The new algorithm uses an expansion technique to construct normal mode eigenvalues and depth functions for some frequency from eigenvalues and depth functions previously calculated at another, higher frequency. Comparisons of the estimated eigenvalues, depth functions, and attenuations with exact results are presented for several shallow water environments. A broadband propagation model that uses normal mode sets calculated with the new algorithm has been developed. Transmission loss and impulse responses based on estimated and exact normal mode sets are compared. [This work was supported by the Office of Naval Research through Block RL3B and Block CS3A.]
The calculation of time domain signals in a waveguide with applications
Authors: Werby M. F. , White E.
Published: October 2005

A fast normal mode code has been developed that is based on an expansion method and a fast Fourier transform integral method. This has enabled one to perform broadband pulse calculations to high frequencies quickly. Further the pulse returns can be decomposed into their constituent modes. Studies on pulse returns were performed for realistic shallow water waveguides for signals out to 25 km and the various dispersion effects and separate model arrivals with increasing distance from the source were illustrated. Particular emphasis is placed on strong channeling. [Work supported by Naval Research Laboratory 6.1 program (element 601153N) with technical management provided by NRL-SSC.]
Scattering investigation with cylindrical acoustic holography
Authors: Cheng Ming-Te , Mann J. Adin
Published: October 2005

The objective of this paper is to investigate sound scattering of a rigid scatterer using a two-plane cylindrical acoustic holography method. A piston source, which is vibrating sinusoidally, illuminates a scatterer. The superimposed incident and scattered fields are measured in the near field of the scatterer using cylindrical acoustic holography. These two fields are decomposed in the wave-vector domain in order to extract the scattered field. Numerical simulations are performed and the effect of various parameters is investigated. Specifically, the distance between the two-holography cylinder, the sampling rate, and the aperture size are investigated in the field separation technique. In addition, experimental studies were conducted inside an anechoic chamber with a baffled loudspeaker as a source and a cylinder as a scatterer. The decomposed scattered field is then used to estimate the far-field target strength. The near-field scattering is also investigated.
New method of investigation of large bandwidth response of mechanical structures
Authors: Lagier M. , Vanderborck G. , Mortessagne F. , Legrand O. , Sornette D.
Published: October 2005

The experimental measurements of high-order mechanical resonances of metallic structures in the high-frequency domain is generally difficult and unreliable, due to the methods of excitations and analysis. Here, an original technique associating a nondestructive percussive excitation together with an acoustic determination of the near field created by the vibrations of the structure in air are proposed. The excitation is obtained using a steel ball magnetically activated, which creates a calibrated impulse. The observation is made using a large bandwidth microphone. The experimentations have been carried out on ‘‘gongs’’ (aluminum plates of 1-mm thickness with other dimensions of the order of the meter) possessing noncanonical shape (stadium, sarcophagus...). With this high signal-to-noise ratio obtained in an anechoïc room, it is possible to obtain several hundred eigenfrequencies with a resolution of the order or better than 1/10th the difference between neighboring frequencies. This was attained without any particular treatment other than the spectral LMS analysis. The signal dynamics is around 80 dB, which allows one to obtain the pole and zeros of the transfer function, implying that the amount of information thus obtained is considerable. The results were then compared with those predicted within the theoretical framework proposed previously, in terms of quantum chaos methods applied to high-frequency vibrations of structures, in order to characterize the nature of the spectrum and the vibration eigenfunctions.
Vowel classification using a microsegmental model for formant transition based on locus equations
Authors: Deng L. , Braam D.
Published: October 2005

In the work by Sussman etal. [J. Acoust. Soc. Am. 90, 1309–1325 (1991)], locus equations, which describe linear relationships between the onset and steady-state formant values in consonant–vowel syllables, have been experimentally tested using a large quantity of acoustic data and been proposed as a source of relational invariance for stop place categorization. In this presentation, a statistical model is presented, which utilizes the conceptualization of the locus equations as a basis for parametric modeling of phonetic contexts—place of articulation, and of their acoustic consequences—formant transitions. The model is based on hidden Markov model representation of formant–transmission microsegments of speech. A generalized expectation-maximization algorithm is developed for automatic estimation of the model parameters. The proposed model is capable of generalizing consonant characteristics from a small training data set where the contextual information is only sparsely represented, and is hence applicable to very large vocabulary speech recognition problems. Results from vowel classification experiments (TIMIT database), demonstrating relative performance between this locus-based model and the conventional hidden Markov model, will be presented.
The phonological reality of locus equations across manner class distinctions: Preliminary observations
Authors: Sussman Harvey M.
Published: October 2005

Locus equations, regression fits to coordinates obtained by plotting F2 of a variety of vowels at their midvowel nuclei in relation to F2 at the acoustic onset of the CV syllable have been shown to phonetically index place of articulation within oral stop categories across speakers of diverse languages—English, Swedish, Cairene Arabic, Thai, and Urdu. The purpose of this study was to determine if locus equations best encode featural or segmental entities. Several consonantal manner classes were assessed. The inventory consisted of CVt tokens having initial approximants—/w/, /j/, /r/, /l/; fricatives—/v/, /hooked schwa/, /z/, /yog/; nasals—/m/, /n/. In addition voicing contrasts were examined using voiceless stops (s/C1/VC2) with C1=/p/,/t/,/k/. Ten medial vowel contexts were used. Locus equations were found to acoustically distinguish place contrasts within each manner class, with nasality and voicing not affecting the place feature. However, similar place features across stop–fricative–approximant classes, did not correspond in terms of slope and y-intercept values. It was concluded that locus equations best characterize segment-based rather than feature-based, entities.
Effects of speaking rate, focal stress, and sentence position on spectral characteristics and vowel duration
Authors: Behne Dawn M. , Nygaard Lynne C.
Published: October 2005

Speaking rate, focal stress, and sentence position can affect the duration and spectral characteristics of vowels [e.g., B. Lindblom, J. Acoust. Soc. Am. 35, 1773–1781 (1963)]. However prior research has been less than conclusive in characterizing effects of these factors [cf. e.g., T. Gay, J. Acoust. Soc. Am. 63, 223–230 (1978)]. Previous findings [D. M. Behne and L. C. Nygaard, J. Acoust. Soc. Am. 90, 2254(A) (1991)] have confirmed the combined effects of these factors on vowel duration and have shown that vowels can be independently affected by speaking rate, focal stress, and sentence position. The goal of this paper is to characterize the effects of these factors on formant frequencies of vowels and relate them to effects on vowel duration. Using the vowels /i, o, a, æ/, conversations were developed with /kVt/ and /kVd/ as target words. In each conversation a target word occurred in initial and in final sentence position and was either focused or nonfocused by the discourse. Twelve subjects produced each conversation at three speaking rates. The present results demonstrated no effect of either speaking rate or focal stress on the spectral characteristics of the vowels, but relatively high first formant frequency and low second formant frequencies for vowels in final sentence position compared to initial sentence position. These findings verify that speaking rate, focal stress, and sentence position can concurrently influence syllable-internal timing with distinct acoustic effects. The results will be discussed in terms of vowel reduction and undershoot.
Inferring articulatory movements from acoustic properties at fricative-vowel boundaries
Authors: Wilde Lorin
Published: October 2005

Formant transitions provide context-dependent acoustic cues that can be interpreted in terms of the articulatory kinematics involved in moving from a consonant to a vowel. Formant frequencies were measured at identified acoustic landmarks for eight English fricatives preceding front, back, and back-rounded vowels. Formant onset times designated the point when the energy increased most rapidly and evidence of the first formant was first observed. Comparing the two-dimensional representation of F2×F3 onset frequencies along the voicing dimension showed the voiceless fricatives to be more dependent on vowel context. The onset frequencies for voiced fricatives reflect a more extreme supraglottal posture, while the voiceless fricative measures can be considered to be at a point closer to the vowel because voicing begins at a later time relative to the oral release gesture. Formant structure in the noise before the release, to the extent that it is visible in the consonantal interval prior to voicing onset, can provide additional place information for voiceless fricatives. Formant onset data are compared with measurements reported from investigations of place categorization of stop consonants. [Work supported by NIH.]
The effect of learning due to voice assessment in acoustic analysis of vocal tremor in patients with Parkinson’s disease
Authors: King Judith B. , Lemke Jon H. , Winholtz William S.
Published: October 2005

For years researchers have questioned the influence of learning from baseline assessments. In a 3-yr study of 14 Parkinson’s patients who received no speech treatment, investigators studied phonatory variability and the effect of learning due to voice assessment. Statistically significant constant decline in weighted mean values were found to exist over time on acoustic variables of maximum performance. A strong learning experience as a result of baseline assessment was also documented. However, measures of maximum performance are notoriously variable, potentially unstable and have been linked to effort, motivation, and learning. Therefore, the present study was designed to examine the effect of learning reflected among the same group of 14 subjects but on a more sensitive, less motivationally dependent phonatory variable. Amplitude- and frequency-demodulated outputs and measures of frequency and level (percent) of low-frequency vocal tremor components in sustained phonation were analyzed. Growth curve analysis models were constructed to simultaneously estimate a constant rate of decline of the variables over time (excluding the influence of baseline values) and to estimate the effect of learning due to baseline assessments. Preliminary data from this study enhance the understanding of the progressive nature of Parkinson’s disease among untreated subjects, and further define which acoustic measures of voice are more sensitive to the effect of learning. [Work supported in part by DC 00976 from the National Institute on Deafness and Other Communication Disorders; Organized Research Grant, Northern Arizona University.]
Propagation of transient waves in a random medium
Authors: Wenzel Alan R.
Published: October 2005

A theoretical analysis of the propagation of transient scalar waves in a one-dimensional random medium is presented. The index of refraction of the medium is assumed to deviate only slightly from unity, which allows the analysis to be carried out with the aid of a perturbation method. The specific approach adopted here combines a renormalization technique with a travel-time-corrected averaging procedure called asynchronous ensemble averaging. A general expression, valid for an arbitrary initial disturbance, is obtained for the variance of the wave. From that result, an expression for the variance is derived for the special case in which the initial disturbance has the form of a ramp function with arbitrary slope. These results show that the variance of the wave is directly proportional to the variance of the refractive index of the medium, but is only weakly dependent on the propagation path length. It is also found that, as the slope of the ramp function decreases, the wave variance decreases as well. The presentation concludes with some observations on the relevance of these results to the problem of sonic-boom propagation in the atmosphere. [Research supported by NASA.]
Comparison between short-term and long-term averages of turbulence parameters for use in atmospheric acoustics
Authors: Noble John M.
Published: October 2005

Sonic anemometers are good instruments for measuring temperature and wind speed fast enough to calculate the temperature and wind structure parameters used to calculate the variance in the acoustic index of refraction. The problem is how long of an average is needed to obtain a representative value of the strength of the turbulence field in the atmosphere. In addition to this problem, there are several problems associated with making point measurements and using them to represent a turbulence field. These problems will be examined by analyzing some of the sonic anemometer data from the Joint Acoustic Propagation Experiment (JAPE) conducted during July 1991 at DIRT site located at White Sands Missle Range, New Mexico. This experiment provides turbulence data from sonic anemometers at five heights for several hours a day over a period of approximately 2 weeks.
Low-frequency wind noise for a microphone inside a spherical foam windscreen
Authors: Morgan Scott , Raspet Richard
Published: October 2005

Windscreens are commonly used to reduce wind noise in outdoor measurements by shielding the microphone from the incoming flow. In this paper a theoretical model for wind noise reduction of a spherical foam windscreen and experimental evidence supporting this model are presented. Results show that wind noise reduction is approximately independent of windscreen diameter for turbulence scale sizes that are much larger than the windscreen and that wind noise reduction scales well with the screen number (defined as the ratio of the windscreen diameter to the scale size of the turbulent eddies) for screen number values less than one. Calculations using average windscreen surface pressure measurements yield wind noise reductions that are of the same order of magnitude as those measured.
Flare noise damage potential
Authors: Moritz C. , Bruce R.
Published: October 2005

Large elevated refinery flares produce significant acoustic power during periods of heavy flaring. Much of this sound power is low frequency, typically in the 4- through 16-Hz octave bands. The intense low-frequency sound can excite resonance frequencies in houses leading to noticeable vibrations of the walls. Through experimental investigations and published data, correlations between hydrocarbon and steam injection flow rates and far-field sound pressure levels were determined. In addition, correlations between sound pressure levels and typical residential wall vibration levels were also similarly determined. From these relationships, the potential for flare noise-induced vibrations to cause cosmetic damage to nearby houses will be discussed.
Active control of liquid-borne energy in a pipe with a uni-directional wave generator
Authors: Louie Lisa
Published: October 2005

Active attenuation of narrow-band sound in a liquid-filled steel pipe was conducted experimentally. The pipe is connected to a noise source at one end and opened into a large reservoir at the other end. For active cancellation purposes, a pair of flush-mounted actuators are located in the mid-section of the pipe. The pair of actuators are used to send a uni-directional wave that is equal in amplitude but 180 deg out of phase to the propagating wave down the pipe. The consequence of implementing this technique is that there is no increase of energy between the noise source and the actuators. Results are recorded by hydrophones located in many locations along the pipe and in the reservoir. Over 20-dB reduction was achieved. [Work supported by ONR.]
Active noise control applied to extended sources in a half-space
Authors: Shepard Steve , Cunefare Kenneth A.
Published: October 2005

Recent work adapted free-field boundary element method-based optimal active noise control techniques for application in a half-space with a rigid or pressure release boundary. Here the required control source strengths and relative phases for active noise control applied to a rectangular solid above a rigid plane are investigated. It is assumed that one face of the solid is radiating harmonically with known surface normal velocity. The existence of unique behavior, as compared to free-field conditions, for the control source strengths and achievable power reduction due to the presence of the plane is demonstrated. This unique behavior occurs at and near certain discrete frequencies. These frequencies are not the characteristic frequencies of the Helmholtz integral for the rectangular solid; rather, they are related to the particular noise source velocity distribution and control source distribution. Finally, the half-space control formulation is employed to evaluate data from an experiment conducted in a hemi-anechoic chamber.
Pulse-splitting in a nonlinear waveguide
Authors: Larraza Andrés , Coleman William F. , Atchley Anthony A.
Published: October 2005

A nonlinear effect in an acoustic duct is described for waveguide modes above the first cutoff frequency, whereby a finite extent modulation of the nonlinear mode splits into two disturbances moving with two different velocities of propagation. That is, for each bit of information input, there will be two bits output. The effect was first predicted by Whitham for nonlinear dispersive media [G. B. Whitham, LinearandNonlinearWaves (Wiley–Interscience, New York, 1974)]. An experiment to verify this phenomenon will be discussed. The apparatus consists of a 21-m-long, 7-segment, thick-walled aluminum tube with a 2-in. internal diameter. Two high-intensity compression drivers arranged in a push–pull configuration are mounted at one end to drive a mode above the first cutoff frequency. A 3-m anechoic termination spanned the length of the last segment at the other end. A physical explanation of the effect, a simplified perturbative treatment of the problem, and possible applications to fiber optic communications will be presented. [Work supported by ONR and NPS Direct-Funding Program.]
Large sets of frequency hopped codes with nearly ideal orthogonality properties
Authors: Rickard Scott T. , Fricke J. Robert
Published: October 2005

Significant performance improvements would be realized in many sonar systems if only it were possible to have multiple pings in the water at any given time. The use of orthogonal frequency hopped codes is one way to achieve multiple, simultaneous access. These codes can be designed to have nearly ideal autoambiguity and low cross-ambiguity properties. In some applications it is desirable to use codes drawn from a very large set, say O(10 000). This paper discusses how such a set can be generated. Specifically, the trade-off between auto/cross ambiguity properties, time-bandwidth product, and code set size when generating large sets are explored. For codes with N frequency hops, the focus is on techniques for generating more than O(N) codes, which characterizes most code generation techniques. Others are nonlinear in N. In particular, the Golomb–Costas method generates O(N2) codes. These codes are ‘‘full’’, which means every available frequency is used in every code. The Reed–Solomon method, in contrast, generates O(Nk) codes, where k is a trade-off parameter proportional to sidelobe level in the cross-ambiguity function. Reed–Solomon codes, however, are not ‘‘full.’’ The trade-off between fullness and number of codes is illustrated. [Work supported by C. S. Draper Laboratory.]
Detection of a submerged object insonified by beach noise
Authors: Makris Nicholas C. , Kuperman William A. , Ingenito Frank
Published: October 2005

In a previous paper, numerical simulations were performed which demonstrated that a submerged object insonified by surface noise in an ocean waveguide can be detected at low to mid frequency for realistic arrays within about 1-km range [Makris etal., J. Acoust. Soc. Am. 92, 2416 (A) (1992)]. For the present paper, an investigation into the possibility of detecting a submerged object insonified by low- to mid-frequency beach noise in an ocean waveguide was carried out. Model beach noise is defined as a one-dimensional array of uncorrelated surface sources and the detectability of the object is investigated for various orientations of the sensing array axis, beach axis, and object.
Contrasting speech and singing—Performance demonstration
Authors: Scherer Ronald C. , Church Tony , Root Renee Skravanos
Published: October 2005

Nonamplified voice and speech for the stage imposes different production requirements than during conversational speech. Tony Church, noted Shakespearean actor and Dean of the National Theatre Conservatory, and Renee Skravanos Root, operatic and recital artist and singing teacher, will demonstrate voice and speech production for the stage relative to contrasts of communication intent and requirements for audibility and intelligibility. Open discussion and research connections will accompany the demonstrations.
A mapping between trainable generalized properties and the acoustic correlates of distinctive features
Authors: Johnson Mark A.
Published: October 2005

It has been suggested that the acoustic correlates of distinctive features may be most reliably measured relative to important acoustic events, or landmarks [K. N. Stevens etal., Proc. Int. Conf. Spoken Language Process. 1, 499–502 (1992)]. Theoretical and empirical literature in the field of phonetics describes many of the acoustic correlates of distinctive features, but these acoustic correlates are often described in terms of formant frequencies and amplitudes, aspiration noise, and other attributes which are difficult for a speech recognizer to measure reliably. This paper reports on a preliminary attempt to compile a table of acoustic correlates of distinctive features, and to map these correlates to reliable acoustic measurements in the vicinity of an acoustic landmark. The acoustic measurements are simple energy and spectral change measurements, defined in terms of frequency and timing parameters which may be optimized for maximum feature discrimination using the technique described by Phillips and Zue [Proc. Int. Conf. Spoken Language Process. 1, 795–798 (1992)]. The table is indexed by distinctive feature, and if an acoustic correlate is likely to be salient only in a given phonological context, the context is given as a list of neighboring and simultaneous distinctive features. [Work supported by NSF.]
A speeded-discrimination task is used to examine processing dependencies between pitch and place of articulation
Authors: Sharma Anu , Carrell Thomas D. , Kraus Nina
Published: October 2005

Speeded classification of stimuli varying along two independent acoustic dimensions is frequently used to study perceptual processing of dependencies in speech perception. Reaction times are compared for different presentation sequences to infer perceptual dependencies. Initially, Wood [J. Exp. Psychol. 1, 3–20 (1975)] observed a unidirectional dependency relation demonstrating that the processing of place of articulation is dependent on the earlier processing of pitch. Subsequently, other investigators reported diverse patterns of dependencies for different stimulus parameters. However, it is not clear if these dependencies are specific only to the speeded-classification paradigm. The purpose of this experiment was to try to generalize Wood’s (1975) results using a different paradigm. The processing dependencies between pitch and place of articulation using a speeded-discrimination paradigm were chosen for examination. The basic principle of the experiment was the same, however instead of classifying the sounds, subjects had to discriminate pairs of sounds using a two-choice (‘‘same’’ or ‘‘different’’) discrimination task. The overall pattern of results was similar to Wood’s study, i.e., there exists an asymmetric dependency between pitch and place of articulation. Furthermore, this pattern of results was observed for ‘‘same’’ as well as ‘‘different’’ reaction times. A second finding (not reported by Wood) was that the error rate data showed the same pattern of results as the reaction time data. Finally, it appears that speeded discrimination requires a greater level of selective attention and cognitive processing for the decision making process than speeded classification.
Effects of internal attachment on sound scattering from cylindrical shells
Authors: Guo Y. P.
Published: October 2005

This paper discusses the effects of attachment conditions of internal structural loading on sound scattering from cylindrical shells. The internal loading is modeled as circular elastic plates. It will be shown that strongest scattering results from attachment that constrains tangential motions in the shell, because this kind of attachment interacts with compressional and shear waves most strongly, which are dominant waves contributing to the scattered field and are essentially associated with tangential motions in the shell. This is in sharp contrast to sound scattering from structural joints in plane geometries, a flat plate, for example, where the scattered field is dominated by constraints that restrict motions normal to the plate. This suggests that sliding joints in shell like structures should be acoustically beneficial.
Waves in a cylindrical shell stiffened by a helical rib
Authors: Kim K. Steven
Published: October 2005

In vacuo elastic wave propagation characteristics in an infinite cylindrical shell stiffened by an infinite helical rib are investigated analytically. Equations of motion of the helical rib and of the cylindrical shell in helical coordinates are developed. They are combined into a single set of equations using appropriate boundary conditions. Dispersion curves of the elastic waves propagating in the shell are obtained for different pitch angles. Comparisons with wave propagation characteristics in an unstiffened shell are discussed.
Perception of the [m]–[n] distinction in VC syllables produced by child and adult speakers
Authors: Ohde Ralph N. , McMahon Christine W. , Haley Katarina L.
Published: October 2005

This research extends previous developmental studies on the perception of the [m]–[n] distinction in CV syllables [R. N. Ohde and K. Haley, J. Acoust. Soc. Am. 92, 2463(A) (1992)]. With only one exception, three talkers for each age level of 3, 5, 7, adult female, and adult male produced VC syllables consisting of either /m/ or /n/ in the context of four vowels /iæuopen aye/. Two productions of each syllable were modified using waveform editing techniques so that the distribution of place of articulation cues for consonant perception could be determined. Ten adults identified the place of articulation of the nasal from several murmur and vowel transition segments. Preliminary findings indicate that the salience of the place of articulation feature from spectral discontinuity cues is substantially weaker in VC syllables than CV syllables, particulary in children’s productions. The findings for the perception of speech segments will be discussed relative to (1) The independence of formant transitions in the vowel and the murmur spectrum as cues to place of articulation in VC syllables, and (2) the developmental role of spectral change between the vowel and the murmur in syllable acquisition. [Work supported by NIH, DC00464.]
A new masked spectrum representation applied to English /r/–/l/ dissimilarity measurement
Authors: Aikawa Kiyoaki , Yamada Reiko A.
Published: October 2005

This paper proves that a dynamic cepstrum is effective not only in automatic speech recognition, but also in explaining the speech perception mechanism. Talker dependency on the perception of American English /r/–/l/ in Japanese listeners has been reported [J. S. Logan etal., J. Acoust. Soc. Am. 89, 874 (1991)]. In order to interpret this phenomenon with regard to the acoustical properties of the stimuli, talker dependency is assumed to be caused by the acoustical dissimilarity of the stimuli. This paper applies a dynamic cepstrum to measuring the dissimilarity of the stimuli. The dynamic cepstrum is a new spectral representation for automatic speech recognition that incorporates the time-frequency characteristics of forward masking [K. Aikawa etal., J. Acoust. Soc. Am. 92, 2476(A) (1992)]. This parameter enhances formant shifts and suppresses stationary spectral features. In a perception experiment, identification tests for English /r/–/l/ minimal pairs uttered by five talkers were conducted. The dynamic cepstrum and a conventional cepstrum were compared for their performance in measuring the acoustical dissimilarity of the minimal pairs. The /r/–/l/ dissimilarity measured by the dynamic cepstrum shows a talker dependency highly correlated with the talker dependency of the perception experimental results. [Speech data were provided by Dr. D. B. Pisoni, Indiana University.]
The perceptual weighting of acoustic cues changes with linguistic experience
Authors: Nittrouer Susan , Manning Carol , Meyer Gina
Published: October 2005

Previous studies found that children’s judgments of syllable-initial /s/ and /∫/ are more related to the vocalic F2 transition and less related to the fricative-noise spectrum than are adults’ judgments [e.g., Nittrouer, J. Phon. 20, 351–382 (1992)]. Such results have led to a model of speech development proposing that children’s weighting of acoustic cues changes as they gain linguistic experience. The present study tested two requisites of that model, namely that the perceptual weighting of acoustic cues must be flexible and cannot simply reflect a listener’s auditory sensitivities. Adults and 3-year olds participated in two tasks: Identification tasks, using synthetic fricative noises and either natural or synthetic vocalic portions; and discrimination tasks, measuring sensitivity to fricative-noise spectrum and F2 transition. Identification tasks showed the same age-related differences found in earlier studies when natural vocalic portions were used, but these age effects were reduced when synthetic vocalic portions were used. Discrimination tasks showed slightly larger difference thresholds for both the fricative noise and the F2 transition for children than for adults, but this age effect could not explain the age effect on the weighting of those cues for identification. It was concluded that the weighting of acoustic cues is flexible both for adults and for children, and that age-related differences in the weighting of the cues to /s/ and /∫/ are not explained by age-related differences in auditory sensitivities. [Work supported by NIH.]
Effects of vibrato and vowel matching on choral blend: A correlation of spectral analyses and perceptual evaluations
Authors: Brown Lawrence R.
Published: October 2005

Four singers (soprano, alto, tenor, and bass) simultaneously recorded unison /a/ vowels on middle-C (261 Hz) in seven different conditions: No instruction, matching or aggregating vibratos, matching or aggregating a nonvibrato tone quality, matching vowel qualities with and without vibrato, and prescribed instructions for a ‘‘target’’ vowel with and without vibrato. A perceptual panel of choral directors, singers, and naive auditors rated the blend or homogeneous quality of randomized samples of the unison vowels. Spectral analyses of the unison /a/ samples indicated varying deviations of the actual frequency of the first 14 partials (0–4000 Hz) from the calculated integer multiples of the fundamental frequency. The tabulated results of the auditors were correlated with the percentage error between actual and calculated partial frequencies. [Work supported by NIH Grant No. R08 DC01150-03.]
Convolution formulation of leaky wave contributions to scattering by plates and by cylinders and shells of variable curvature
Authors: Marston P. L.
Published: October 2005

A novel high-frequency formulation is investigated that approximates the leaky wave amplitude at the scatterer in terms of a spatial convolution of the local incident wave pressure and a one-sided line response function h(s≥0)=−jα exp(−αs+ikls). Here, s is the propagation distance along the flat or curved surface, α is the reciprocal of the attenuation length, kl the real part of the wave number, and j=1 for equal fluid loading on both sides of a plate but j=2 for one-sided fluid loading of a shell or for Rayleigh waves on a solid. Application to plane waves incident on cylindrical surfaces (empty shell or solid) of slowly varying curvature yields the following far-field amplitude from a leaky ray propagating a distance S on the surface: pl=−2αpinc(2πa1a2/ kr)1/2 exp(−αS+iπ/4+iη), where a1 and a2 are the radii of curvature at the launching and detachment regions and η is a geometrical phase accumulation. When a1=a2, the coupling coefficient Gl for a circular cylinder derived previously is recovered. The result can be modified to situations where α varies weakly with curvature. [Work supported by ARL:UTIR&D Program and by ONR.]
Scattering of waves from ribs on fluid-loaded plates
Authors: Wang Zhang , Norris Andrew
Published: October 2005

A new formulation of the Green’s function for a fluid-loaded infinite plate under line loading is presented. The Green’s function is expressed explicitly in terms of a sum of the five free modes of propagation plus a semi-infinite integral. The Green’s function itself and its first and second derivatives at the loading line are obtained in analytic forms that prove to be useful in computing the scattering matrix for a rib on the plate. The scattering matrix for an isolated rib is derived. It is shown that the wave incident onto one of the n-arbitrary ribs on the plate can be written as a product of the original incident wave and a matrix, referred to as the influence matrix, which reflects the alteration of the incident wave on one rib produced by the presence of the other ribs. The influence matrix is an inverse of a matrix whose elements are the scattering matrices for single ribs and unit matrices, and it can be expanded as an infinite series which converges rapidly. Each term in the infinite series may be interpreted as a generalized ray. Numerical results are presented and compared with previous work. [Work supported by ONR.]
Diffraction effects from the joining of two curved plates
Authors: Rebinsky Douglas , Norris Andrew
Published: October 2005

Acoustic scattering from a fluid-loaded shell consisting of two joined curved plates is considered. Asymptotic approximations are made based upon the assumption that the fluid wavelength is much shorter than the smaller radius of curvature. A plane wave in the fluid incident upon a line weld at which the shell properties and curvature are discontinuous, but the tangent is continuous, is considered. The problem simplifies by first assuming that the angle of incidence with respect to the tangent plane at the weld is not near the critical angle for supersonic membrane waves on either side of the weld. The discontinuity then generates a diffracted wave field in the fluid which is determined by solving a Wiener–Hopf problem. This background wave field in turn forces the ordinary differential equations describing the membrane waves. From their solution, diffraction coefficients are obtained for the membrane waves generated on each curved plate by the incident acoustic field. When the incident wave is close to one of the critical angles it couples directly to the shell waves via curvature, and the interaction of this launched membrane wave with the discontinuity results in scattered membrane wave fields with diffraction coefficients determined in a manner similar to the previous case. [Work supported by ONR.]
A simple demonstration of impedance matching in driven resonant tubes
Authors: Gabrielson Thomas B. , Gardner David L.
Published: October 2005

Resonant tubes are often used in teaching laboratory experiments to demonstrate a wide range of topics from standing waves to lumped-parameter approximations and electroacoustic analogues. The popularity is understandable given the ease of construction and the broad applicability outside the laboratory, ranging from impedance tubes to musical instruments. While the measurement of standing waves and modes is common, the relationships, in an open-ended tube, between the tube, the radiation impedance, and the driver impedance is less frequently addressed. In this experiment using inexpensive components and a Smith chart, the resonances of a small loudspeaker and of an open tube are measured. The radiation impedance at the tube end is transformed to the driver location and the resulting reactance is compared to the loudspeaker reactance. The tube resonances are thus demonstrated to occur when the two reactances are equal, but of opposite sign.