bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement and suppression of acoustic streaming using tone-burst waves
Authors: Mitome Hideto , Kozuka Teruyuki , Tuziuti Toru
Published: October 2005

Acoustic streaming is generated even by tone-burst waves, because the driving force is given by a time-averaged value of the acoustic properties. It was pointed out theoretically that the driving force of the streaming is enhanced at a higher level of sound pressure. If the applied electric power is kept the same, a tone-burst wave with a shorter active period has a larger source amplitude, which brings a stronger driving force. The present paper describes experimental results of acoustic streaming driven by tone-burst waves of various parameters using a laser Doppler velocimeter and shows that the enhancement of streaming is due to nonlinear attenuation of ultrasound. The generation of streaming is often observed in noncontact manipulation using acoustic radiation pressure, which is undesirable for the stable operation. Noting the difference in the time scales of the phenomena, incorporation of a tone-burst wave of the same amplitude makes it possible to suppress the generation of acoustic streaming (slow mode), keeping the sufficient strength of acoustic radiation pressure (fast mode). Experiments of acoustic manipulation of suspended particles showed that this medium-mode operation worked well.
Perturbation and physics: A question raised in standing wave study
Authors: Maa Dah-You
Published: October 2005

The perturbation method is a powerful tool in the treatment of nonlinear problems in physics. In the history of nonlinear acoustics, however, it was found unsuccessful when a standing wave was treated. In the Laplacian system of coordinates, the second-order approximate differential equation, after the first-order particle velocity u(1) is substituted, yields an ever-increasing solution for the second-order quantity u(2). The result is certainly mistaken; how can an unstable solution come out of a stable system like the standing wave? From the physical considerations, the second spatial derivative of u(2) should not be preserved in the differential equation. The reason is that u(2) is merely the modification of u(1) at different points on the waveform due to nonlinearity, and its distribution is completely determined and accounted for by that of u(1) through the nonlinear term in the equation. The solution thus obtained is stable and agrees well with the exact solution. On the other hand, the Laplacian sound pressure derived from the particle velocity does not convert to the Eulerian one by the transformation of coordinates, the variable air density and sound velocity must be taken into account. Physics must be kept in mind when the perturbation method is applied. [Work supported by NNSF, PROC.]
Observation of VHF nonlinear wave propagation in the SiO2/water/SiO2 ultrasonic transmission line
Authors: Kushibiki J. , Sannomiya T. , Akashi N. , Ishibashi M. , Chubachi N. , Dunn F.
Published: October 2005

A bioultrasonic spectroscopy system and method for studies of ultrasonic tissue characterization in the VHF and UHF ranges were recently developed. Bulk linear acoustic properties of velocity, attenuation coefficient, impedance, and density can be determined in an ultrasonic transmission line in which the specimen is sandwiched between two SiO2-buffer rods, having ZnO-film ultrasonic transducers on their outer ends, and with distilled water employed as the reference medium. An extensive study of the linear and nonlinear acoustic propagation behavior of liquids/tissues at these high frequencies has been initiated. In this paper, nonlinear wave propagation in the system of SiO2/water specimen/SiO2 in the frequency range of the fundamental from 100 to 200 MHz is discussed theoretically and empirically for an input fundamental-frequency ultrasonic power of about 1 mW. A new method of measuring the nonlinearity parameter of liquids is proposed, taking notice that the sign of the nonlinearity parameter of SiO2 is different from that in liquids. The nonlinearity parameter is determined by measuring the distance between two rods at which the second-harmonic-component output of the receiving transducer becomes zero, with reference to the nonlinearity parameter of SiO2.
Measurement of the acoustic nonlinearity parameter in water–oil mixtures at sol and gel states
Authors: Saito Shigemi , Iwano Jun-ichi , Mizuno Hiroyasu
Published: October 2005

To produce materials mimicking biological soft tissues available for finite-amplitude bioacoustics, the acoustic nonlinearity parameter B/A in a water–oil mixture at the sol and gel states has been investigated experimentally. The sol sample was supplied by ultrasonically emulsifying a mixture of rapeseed oil and water at various volume fractions. The gel was obtained by mixing gelatin powder to the warmed sol. The B/A was measured by utilizing the fundamental and second-harmonic components of a 1.9-MHz focused Gaussian beam, while the sound speed was measured by the sing-around method applied to the same focusing system [S. Saito, J. Acoust. Soc. Am. 93, 162–172 (1993)]. The measured data have been investigated through comparison with the previously proposed mixture rules [R. E. Apfel, J. Acoust. Soc. Am. 74, 1866–1868 (1983); C. M. Sehgal et al., Ultrasound Med. Biol. 12, 865–874 (1986)].
Acoustical properties around the sol–gel transition point in gelatin
Authors: Choi Pak-Kon , Takahashi Hisashi , Yamamoto Akio
Published: October 2005

Sol–gel transitions in gelatin are studied using a plano-concave resonator method for measuring ultrasonic velocity and absorption in the 0.2- to 3-MHz range, and also using a surface-wave method for measuring shear elasticity and viscosity in the hundreds of Hz range. The temperature dependences demonstrate the small decrease in ultrasonic velocity and the large increase in absorption upon gelation. These results show marked contrast with those of the low-frequency surface-wave measurements that agree with the percolation theory. The frequency dependence of ultrasonic absorption indicates a distribution of relaxation time. The mechanism of the ultrasonic behaviors is discussed in terms of the random coil–helix transition and hydration of gelatin molecules.
Solitonlike thermoelastic waves revisited
Authors: Ignaczak Józef
Published: October 2005

In earlier papers [cf. for example, R. B. Hetnarski and J. Ignaczak,Proceedings of the First International Symposium on Thermal Stresses,Thermal Stresses ’95, Shizuoka University, Hamamatsu, Japan, 5–7 June (1995), pp. 271–274; and R. B. Hetnarski and J. Ignaczak, Int. J. Eng. Sci., to be published in 1996] a low-temperature nonlinear thermoelastic model has been proposed in which one-dimensional solitonlike waves may propagate. Both exact and asymptotic solutions to the nonlinear governing equations have been obtained there. In the present paper a further study of the one-dimensional model is given. A new approximation to the nonlinear governing equations is postulated, and two implicit-form solitonlike solutions valid in a neighborhood of thermodynamical equilibrium are obtained. The two solutions are less restrictive than the asymptotic solutions obtained earlier, and one of them corresponds to a slow quasithermal wave, while the other matches a fast quasimechanical wave. The graphs illustrating the solutions are included.
Propagation of intense acoustic pulses with shocks in relaxing fluids
Authors: Sapozhnikov Oleg A. , Andreev Valery G. , Khokhlova Vera A. , Pischal’nikov Yury A. , Cleveland Robin O.
Published: October 2005

The propagation of intense waves in liquids or gases with relaxation processes is a classical problem of nonlinear acoustics. The presence of relaxing processes influences acoustic propagation by changing the absorption law and introducing dispersion. The effect of the relaxation is of particular interest for short acoustic pulses, when the duration of pulse is of the same order as the characteristic relaxation time. Even for the case of linear acoustics, relaxation will compromise pulse shape. For intense waves, nonlinear effects result in additional pulse distortion, shock formation, and nonlinear energy attenuation. The propagation of intense acoustic pulses containing shocks is studied theoretically and experimentally. Two numerical simulations, a modified spectral method and a time-domain method, are used to model shock propagation. Propagation curves for waveform distortion, shock amplitude behavior, and energy dissipation are presented. Experiments are performed in acetic acid as a monorelaxing medium. Short acoustic pulses are excited by a pulsed laser. Theoretical and experimental results are in a good agreement. [Work supported by NIH, FIRCA, and RFBR.]
Modeling of nonlinear shock wave propagation in dispersive media with nearly linear frequency dependence of attenuation
Authors: Khokhlova Vera A. , Sapozhnikov Oleg A. , Averkiou Michalakis A. , Hamilton Mark F.
Published: October 2005

Acoustic wave propagation is generally weakly dispersive, and thus frequency dependence of the sound speed is usually considered negligible. However, if absorption does not have a quadratic frequency dependence, dispersion will be important. For broadband signals such as shock waves, dispersion may influence the waveform distortion and the corresponding nonlinear attenuation. These effects are important for the case of biological media which have absorption laws obeying a nearly linear frequency dependence over a wide frequency range. The sound-speed dispersion can be reconstructed from a given attenuation law by the use of the Kramers–Kronig relations. Because attenuation is typically specified over only a restricted frequency range, it is not possible to uniquely reconstruct the dispersion law, and thus an appropriate approximation of the absorption coefficient at high frequencies is required. The effective dispersion law is reconstructed for various absorption models: multiple relaxation, piecewise linear, and power-law absorption. Theoretical modeling of nonlinear wave propagation is performed using a modified spectral approach. The propagation of both shock pulses and periodic sawtoothlike waves is investigated. The results show that it is important to account for dispersion when modeling propagation of broadband finite-amplitude waves. [Work supported by NATO CRG, FIRCA, and RFBR.]
Holographic interpretation of binaural hearing
Authors: Okada Heiji , Tanaka Shin-ichi , Shibayama Kimio
Published: October 2005

Hearing sound means, from the viewpoint of holography, that sound images are reconstructed based upon the signals received by the ear. The reconstructed sound source is an imaginary image, because no sound source exists there when it is reproduced. Such a phenomenon is often seen in a firecracker festival. A description is made hereby comparing a reconstruction method of the usual complex-amplitude-type acoustical holography by a one-dimensional receiving array, and its variation to an additional-squared type of the two point receivers’ output. With the additional-squared-type processing of the two point receivers (which means binaural hearing), observation was conducted in accordance with a holographic method. Provided that human hearing ability is being stimulated with both ears, it is imaged that the sound images are reconstructed by cross-replacing equivalently the right and left received signals to the right and left positions.
Dichotic perception of modulation depth of AM signals
Authors: Ozimek Edward , Konieczny Jacek , Suzuki Yo-iti , Sone Toshio
Published: October 2005

The aim of this study was to evaluate the resultant value of the modulation depth perceived binaurally when sinusoidally amplitude-modulated tones, with different modulation depths, were presented to the left and right ear. Different values of the modulation index (ranging from 0% to 100%), modulation frequency (4, 64, 128 Hz), and carrier frequency (250, 1000, 4000 Hz) were used in the experiment. The data show that for low values of the modulation indexes, the dichotic perception of modulation depth approximates the arithmetic mean of the indexes presented to the left and right ear. However, this is not the case for higher values of the modulation index for which the perceived modulation depth is always lower than the mean of the indexes at both ears. Additionally, it was stated that perceived modulation depth does not depend on the rate of modulation for relatively small interaural differences in modulation indexes. In turn, for larger interaural differences the perceived modulation depth tends to decrease with increasing modulation rate. The model of binaural perception of AM tones is considered. a)Permanent address: Institute of Acoustics Adam Mickiewicz University, Poznan ul. Matejki 48/49, Poland.
Studies of sound localization in a hybrid acoustical environment
Authors: Kulkarni Abhijit , Colburn H. Steven
Published: October 2005

Experiments in a hybrid (natural and virtual) acoustical environment suggest that subjects are largely insensitive to detail in the HRTF magnitude spectra in anechoic space. In the primary experiments, subjects were tested in a 2I, 2AFC discrimination paradigm and were required to judge the order of free-field stimuli (delivered from a loudspeaker) and virtual stimuli (presented from tubephones in the ear canals) for corresponding spatial locations in the horizontal plane. Virtual stimuli were constructed from individually measured HRTFs and delivered near the entrance of the ear canal via tubes that were confirmed to not significantly alter the natural sound field. Each interval consisted of a pair of 80-ms noise bursts separated by 100 ms. Performance of subjects was at chance for all four azimuthal positions tested, even when the HRTF magnitude spectra used for the virtual stimuli were systematically smoothed by large amounts. With extreme smoothing, subjects reported an externalized and elevated sound image, consistent with a natural sound image from a loudspeaker directly overhead. These latter results further suggest that directional features in the HRTF are not responsible for the externalization of sound images. [Work supported by NIDCD.]
Effects of interaural cross-correlation function on subjective attributes
Authors: Sato S. , Ando Y.
Published: October 2005

For the evaluation of subjective diffuseness and subjective preference, the IACC has been utilized. Not only the maximum interaural cross-correlation coefficient IACC for |τ|≤1 ms, but also its interaural time delay τIACC and the width of the interaural cross correlation WIACC (the width of the time of the function crossing zero) are the elements of the interaural cross-correlation function. From the previous study, the IACC and the interaural time delay have influence on the subjective preference of a sound field in an existing hall. Also, it is considered that the width of the interaural cross correlation, which is related to the frequency characteristics of the source signal, has significant effects on the evaluation of ASW.
A computational model of the precedence effect based on echo avoidance
Authors: Huang Jie , Ohnishi Noboru , Guo Xiaolan , Sugie Noboru
Published: October 2005

A computational model of the precedence effect is proposed by assuming that the precedence effect is caused by the inhibition of sound localization which depends on the estimated sound-to-echo ratio. It is found that a generalized pattern of impulse response with delay and decay features can be used for echo estimation. As a real neural implementation, the pattern of an after-effect in the human auditory system, based on the previous psychoacoustic just-noticeable-difference tests of interaural delay and intensity, is adopted. This pattern has delay and decay features similar to those in the generalized pattern of impulse response, and the difference in decay scales is shown to cause little difference in echo estimation. The results of psychoacoustic experiments, e.g., equal-level and unequal-level paired click tests [P. M. Zurek, J. Acoust. Soc. Am. 67, 952–964 (1980); K. Saberi and D. R. Perrott,ibid . 87, 1732–1737 (1990)], Haas’s tests [H. Haas, J. Audio Eng. Soc. 20, 146–159 (1972)], Franssen’s tests [J. Blauert, Spatial Hearing (MIT, Cambridge, MA, 1983)], and others, can be interpreted consistently. This model can also give criteria for an available onset and an explanation of why a transient onset is required for the precedence effect.
Detection thresholds of random amplitude modulation
Authors: Ozimek Edward , Konieczny Jacek , Suzuki Yo-iti , Sone Toshio
Published: October 2005

The main objective of this study was to determine the detection thresholds of random amplitude modulation (RAM) as a function of modulation and carrier frequency. Two experiments were performed. Experiment 1 concerned the detection thresholds of AM stimuli for only random amplitude changes at constant modulation frequency. Experiment 2 dealt with detection thresholds for simultaneous, random changes in amplitude and modulation frequency. The data obtained showed that for low modulation frequency, the detection thresholds for sinusoidal amplitude modulation (SAM), random amplitude modulation at constant modulation frequency [RAM(fm const)], and random amplitude and modulation frequency [RAM(fs random)] overlapped one another in the limit of SD. However, for higher carriers and modulation frequencies the RAM(fm const) thresholds were, in a limited range offm , much lower than the SAM ones. When random changes in modulation frequency were combined with random changes in amplitude, the RAM(fm random) thresholds decreased relative to the RAM(fm const) thresholds. a)Permanent address: Institute of Acoustics, Adam Mickiewicz University, Poznan ul. Matejki 48/49, Poland.
Combinations of forward and simultaneous masking, revisited
Authors: Jesteadt Walt , Neff Donna L. , Kessler Christina J.
Published: October 2005

In previous work, it was found that combinations of a long duration, broadband noise simultaneous masker and a 1000-Hz sinusoidal forward masker can produce as much as 14 dB more masking of a 1000-Hz signal than would be predicted on the basis of a linear power summation of the individual effects of the two maskers. In this study, the effects of masker and signal bandwidth and of simultaneous masker duration on this excess masking were explored. Using a 20-ms sinusoidal signal and a combination of 400-ms broadband-noise simultaneous masker and a 300-ms sinusoidal forward masker, the original effect in a new group of four subjects was replicated. When independent broadband noises served as both maskers and as the signal, and when the simultaneous masker was the same duration as the 20-ms signal, excess masking was completely eliminated. Longer duration simultaneous maskers, a sinusoidal signal, or a sinusoidal forward masker all produced excess masking to varying degrees. No existing model of the additivity of masking provides a good account of these effects. [Work supported by NIH.]
Perception of two-tone mixtures by the goldfish
Authors: Fay R. R.
Published: October 2005

A stimulus generalization paradigm combined with classical respiratory conditioning was used to investigate the perceptual similarities and dissimilarities between single tones and two-tone complexes. Groups of 8 animals were given 40 classical conditioning trials to 6-s pure tones (200, 500, or 700 Hz) and then tested for generalization to two-tone complexes made up of the conditioning tone and a second tone spaced plus or minus 2, 4, 8, 16, 32, 64, 128, 256, 512 Hz from the conditioning tone frequency. Generalization (assumed to be monotonic with judged similarity) reached a minimum for complexes having frequency differences of 36 to 64 Hz, and increased to near 100% for the largest frequency differences (256 or 512 Hz). The dip in generalization at 36–64 Hz suggests that beats at these rates result in a salient perceptual quality that could be similar to roughness or intermittency. The rise in generalization for the larger frequency differences suggests either that roughness gives way to smoothness (a presumed quality of the single conditioning tone), or that the goldfish hears out the conditioning tone in the two-tone complex (analytic listening). These hypotheses will be evaluated in future experiments. [Work supported by the NIH, NIDCD.]
Experimental modal synthesis method for reducing car interior noise
Authors: Yashiro Haruki , Iwama Akinori
Published: October 2005

The experimental modal synthesis method has been very popular for analyzing the dynamic behavior of structures. Recently, the demand for reducing not only vibration but also noise has been increasing in the development of industrial machines. In order to deal with noise and vibration simultaneously, the structural–acoustic coupling problem must be solved. The equations for the coupling system are asymmetric (there is not a reciprocity between displacement and pressure). Experimental modal analysis has been applied to solve the asymmetric equations instead of using numerical methods such as NASTRAN, and its usefulness has been shown. This paper describes its theory and its application to the reduction of low-frequency car interior noise, which is attained with a few refinements to the present modal analysis software.
Contribution analysis of road noise in automobiles
Authors: Nakamura Masanobu , Sawanobori Takeshi , Nagamatsu Akio
Published: October 2005

Noise and vibration problems in automobiles are caused by plural vibration sources and complex transfer paths. In general, diminishing the noise and vibration level is a matter of great importance for a lightweight and low-cost design. In this paper, the noise and vibration problem caused by pavement roughness in automobiles, that is, the road noise problem, is discussed. By means of traction of a vehicle with constant speed, measurement of noise and vibration caused by only the factor of pavement roughness in automobiles is accomplished and the contribution of road noise in automobiles is investigated in detail using acoustic modal analysis and principal component analysis.
Simultaneous design of multiple dynamic absorbers by modal analysis
Authors: Seto Kazuto , Nagamatsu Akio
Published: October 2005

Some approaches to the simultaneous optimum design of multiple dynamic absorbers (DAs) are presented for suppressing multiple resonance peaks of a multiple-degrees-of-freedom (MDOF) structure simultaneously, taking changes of natural modes and natural frequencies of the structure due to added mass effects of DAs into account in the design. First, some methods for determining an equivalent single-degree-of freedom (SDOF) system of the subject MDOF structure are explained, in order to make possible the application of the usual design method for the SDOF system by Den Hartog to the subject MDOF structure. Second, some guides in determining the best place on which DAs should be attached in the subject structure are indicated for giving the best play to DAs efficiencies. Third, three kinds of approaches to the simultaneous optimum design are proposed using the modal analysis. Validity and usefulness of the proposed approaches are demonstrated by both computer simultation and experiment using a plate and a simple structure.
Modal analysis of a circular plate with a solid shaft and a solid cylinder and estimation of radiating sound power
Authors: Hayashi Iwao , Iwatsuki Nobuyuki , Heng Kang
Published: October 2005

The natural modes of flexural vibration of a circular plate with a solid shaft and a solid cylinder, which is a simple model of aircraft gears, were theoretically analyzed with a new method proposed by the authors. The calculated natural frequencies and mode shapes coincided well with the values measured by experimental modal analysis. Using the calculated natural frequencies and mode shapes, the three parameters required for the estimation of radiating sound power—total loss factor, radiation loss factor, and driving point mobility—were calculated, and then the radiating sound power from the circular plate was estimated by the estimation theory proposed by the authors in other papers. The frequency response of the estimated sound power coincided well with the values measured by the sound intensity method.
Estimation of rotational degrees-of-freedom components of experimental mode shapes using an analytical model
Authors: Kuratani Fumiyasu , Okita Kozo , Yano Sumio , Iwatsubo Takuzo
Published: October 2005

Rotational degrees of freedom (RDOFs) have difficulty with measurement, although structural modifications with beam and plate elements require mode shapes including RDOFs. This paper presents a method to estimate RDOF components as a linear combination of mode shapes of the finite-element (FE) model of a test structure. Since the estimation accuracy depends on a set of combined modes, an effective technique for selecting modes to be combined is proposed. This technique is based on the modal assurance criterion (MAC) value which indicates the degree of correlation between experimental mode shapes having only translational degrees of freedom and analytical mode shapes of the FE model. To demonstrate the applicability of the proposed technique, a frame model which has simulated experimental mode shapes with added measurement noise is analyzed. It is confirmed that the optimal set of combined modes can be predicted from the MAC values, although the set differs with each mode number to be estimated.
Estimation of vibrational energy flow by sound energy in a vibrating rectangular plate
Authors: Nakagawa Noritoshi , Higashi Akihiko , Sekiguchi Yasuhisa
Published: October 2005

In the case in which a rectangular plate is excited sinusoidally, the estimation of vibrational energy flow by sound energy is investigated. In this paper, the analysis of both vibration of the rectangular plate and the radiated sound field is performed at each mode of vibration. Furthermore, the changes of vibrational energy flow and sound energy flow are analyzed under the condition of a different damping coefficient. In evaluating the vibrational energy and the sound energy, the structural and sound intensity are used under consideration of three-dimensional vibrational energy and sound energy flow. By discussing the distribution of the vibrational and sound energy and the ratio of sound energy to the vibrational energy, etc., the possibility of estimating the vibrational energy flow by the sound energy is also indicated.
Prediction of interior noise levels in a passenger car compartment
Authors: Morrey Denise , Roly Whear
Published: October 2005

Consideration of interior noise and vibration levels, during the development of a new motor car, has tended to concentrate on the use of structural modal surveys, combined with the measurement of sound-pressure levels in the fully trimmed car. However, there is increasing pressure to reduce development lead times, as well as to provide an improved level of refinement. The work described here uses the finite-element method to predict interior noise levels. A finite-element model of the acoustic cavity of a Rover Metro-R6 has been generated, and frequency response functions of the vibration of the vehicle structure are applied as a forcing function to the boundary. This enables noise transfer functions to be predicted at locations within the cavity such as the driver’s ear, in order to identify any problem areas. Boundary impedance is included in the model to represent the presence of carpet and seats. The impedance values were obtained using the two microphone impedance tube method [ASTM Standard E1050-86]. Experimental noise transfer functions results were found, using a vibration. These showed good agreement with the predicted values. The boundary element method was also used to investigate panel contribution. [Work supported by Rover Group, UK.]
Acoustic analysis of plane-wave transmission through a duct of a thick wall
Authors: Sato Ryoichi , Shirai Hiroshi
Published: October 2005

Analysis of sound transmission and penetration through a duct of a wall is one of the basic but important problems in structural acoustics. If the wall is thin, then the configuration may be regarded as a slit of zero thickness, and the treatment is rather easy. For the thick wall, however, one has to consider the duct propagation and the problem becomes somewhat involved. In this paper, plane-wave transmission through a two-dimensional duct of a rigid wall is treated rigorously and formulated as a boundary-value problem [K. Hongo and G. Ishii, IEEE Trans. Antennas Propag. AP-26, 494–499 (1978)]. First, the scattering field in each region is expressed in terms of appropriate eigenfunctions with unknown excitation coefficients. Then the continuity condition of the field at the aperture of the duct has been used for determining them. Starting from a rigorous solution, one can also derive a simple formula for estimating the transmission field through a small-aperture duct. Numerical computations have been done extensively and compared with those by other methods. Good agreements are found between this solution and others. Validity of the small-aperture approximation will also be discussed.
The grouping phenomenon of the radiation efficiencies of acoustic modes
Authors: Currey M. Noelle , Cunefare Kenneth A. , Johnson M. , Elliott Stephen
Published: October 2005

The modal-style approach for representing the exterior radiation characteristics of structures generally seeks to find a set of orthogonal functions, or acoustic modes, that diagonalize a radiation operator in the exterior domain of the structure. The choice of basis functions, whether global or local, is arbitrary. The acoustic modes are found through an eigenanalysis of the radiation operator, with corresponding eigenvalues which are proportional to the radiation efficiencies. The analytical acoustic modes of a finite sphere radiating into free space are represented by the orthogonal set of spherical harmonics. The spherical harmonics and the modes of arbitrary structures exhibit a grouping among their respective radiation efficiencies at long wavelength conditions. The analytical basis for the grouping within the spherical harmonics provides an avenue for describing the grouping within the acoustic modes of an arbitrary structure. Further, the spherical harmonics provide insight into the shapes of the acoustic modes for arbitrary structures. Here, the acoustic modes of a free-space sphere are compared to those of an arbitrary free-space object, half space object, baffled panel, and baffled beam. [Work supported by NASA GSRP program, NGT-51115.]
Speech movement variability: Data and interpretations
Authors: Gracco Vincent L.
Published: October 2005

Similar to other human behaviors, speech production is hierarchical. Motor planning is represented in a low-dimensional goal space and unfolds into successively more detailed levels of output. The communicative goal requires a balance between the perception and production systems. If these two systems are appropriately tuned a predictability results that facilitates the communication process. One method that can be used to understand the tuning of these two important processes generally, and the speech production process specifically, is examination of output variability under a variety of conditions. Output variability reflects on the precision of the respective processes and on aspects of the goal-level planning. The purpose of this presentation is to investigate aspects of speech movement planning and control through analysis of lip, jaw, and tongue motion. Two complementary approaches will be used. Static spatial positional goals for a variety of phonetic segments of English will be examined. The continuous motion of simultaneous articulator trajectories will also be examined to elucidate the time-varying nature of speech. The interpretation of both static and dynamic movement variability will be related to the characteristics of the production and perception processes. [Work supported by NIH.]
Variability of speech production: A C/D-model perspective
Authors: Fujimura Osamu
Published: October 2005

Variability in speech signals for the same linguistic message, both systematic and random, can be described by an abstract representation of an utterance as manipulation of control variables. Random variation of linguistic variables are often considered speech errors. The C/D model converts segmental and prosodic phonological specifications supplemented by utterance parameters such as speed and style of utterance, speaker’s anatomical and physiological characteristics, emotional state, etc. into continuously variable signals. Such parameter manipulations involve slower changes in system parameters including coefficients for relating the syllable magnitude to syllable component durations, certain limited modifications of parameters in impulse response function (IRF) specifications for elemental consonantal gestures, etc. The relative stability of IRF’s provides a solid basis for the perceptual strategy in segmental identification, whereas relatively free control of base functions related to laryngeal, mandibular, and vocalic dorsal/labial adjustments, possibly with auditory feedback, constitute prosodic variability of the message. Contributions of prosodic variability to the languages’ historical evolution and child language development are also noted. [Work supported in part by research and education funds provided by ATR/ITL and ATR/HIP.]
Statistical analysis of a phonemic target in articulatory movements
Authors: Honda Masaaki , Kaburagi Tokihiko
Published: October 2005

Articulatory motion is a skilled sequential movement in which a phonemic string is converted into continuous movements in the articulatory coordinate system. In generating articulatory movements, the phonemic target or task is often defined as a compact region of either articulatory, vocal-tract geometric, or acoustic space. In this paper, statistical analysis of the phonemic targets obtained from the empirical articulatory and acoustic data is described. The target distribution shows different variants in each space for different classes of sounds. The variance of the target is examined for different conditions of syllable, stress, and utterance speed. Also examined is which articulatory, geometric, or acoustic space is appropriate for specifying the target in forming the articulatory movements using the trajectory formation model with a stochastic target representation [M. Honda and T. Kaburagi, ICSLP 1, 179–184 (1994)].
Phonetic sensitivity and individual recognition: Notes on system architecture
Authors: Remez Robert E. , Fellowes Jennifer M. , Rubin Philip E.
Published: October 2005

A perceiver’s ability to identify a familiar talker is often ascribed to the registration of acoustic attributes of vocal quality. In idealizations of this aspect of speech perception, unique long-term characteristics of the glottal source or the supralaryngeal filter of speaking acquaintances are represented in a mental gallery, and function as standards for evaluating unknown signals that challenge the auditory system. The ability to identify a message spoken by a familiar talker inheres in a different set of acoustic properties, those of finer grain that underlie the perception of consonant and vowel sequences useful for lexical retrieval. Neuropsychological reports of a dissociation between aphasia and phonagnosia suggest a system architecture in which the perception of a linguistic message is functionally independent of the perception of the identity of the talker who produced it. The plausibility of this conceptualization will be discussed in the light of perceptual identification and perceptual learning studies of individual identification without recourse to auditory impressions of familiar vocal quality. Evidence will be presented that phonetic attributes are an intrinsic component of the perception and identification of individuals. [Supported by NIDCD.]
Production and perception of individual speaking styles
Authors: Johnson Keith , Beckman Mary E.
Published: October 2005

As explanation of interspeaker differences in speech production moves beyond sex- and age-related differences in physiology, discussion has focused on individual vocal tract morphology. While it is interesting to relate, say, variable recruitment of the jaw to extent of palate doming, there is a substantial residue of arbitrary differences that constitute the speaker’s ‘‘style.’’ Style differences observed across a well-defined social group indicate group membership. Other style differences are idiosyncratic ‘‘habits’’ of articulation, individual solutions to the many-to-many mapping between motoric and acoustic representations, which may be set in place in the initial acquisition of motor-control representations for speech. Perceptual studies of social style differences suggest that perceptibility depends upon the task and upon the hearer’s own group membership. The few studies of idiosyncratic differences suggest that speakers perceive each others’ productions in terms of their own habits. Thus, perceptual compensation for speaker differences must go beyond mere vocal tract normalization. A promising route for describing how listeners compensate for the arbitrary variation of style is an instance-based (or exemplar) model of speech perception in which the distribution of exemplars is heavily weighted by instances of the speaker’s own productions.
Relationships between individual and phonetic information in speech waves: Their application to automatic speech recognition
Authors: Furui Sadaoki , Matsui Tomoko
Published: October 2005

Various hearing experiments and statistical analyses have been conducted concerning the relationships between individual and phonetic features in speech waves, and the following results have been obtained. (1) Statistical analysis of individual and phonetic information in speech waves shows that the latter is more significant than the former and that they have a significant effect on each other. (2) Hearing experiments using Japanese syllables extracted from continuous speech show that syllables used to perceive individuality are different from speaker to speaker. (3) Syllable identification tests using many speakers’ voices have shown that people can adapt to a new speaker’s voice after hearing just a few syllables, irrespective of the phonetic contents of the syllables. This means that people can generalize individual features extracted from a limited set of phonemes and apply this knowledge to other phonemes. The results from (1)–(3) imply that the same individual features are shared by several phonemes, although not all phonemes. (4) Other hearing experiments show that crucial phonetic information mainly exists in a short speech segment with a large spectral transition. Consequently, the simultaneous and automatic extraction of phonetic and individual information in transitional (dynamic) features of speech is an important research issue for speech information processing, including efficient speaker adaptation techniques in automatic speech recognition.
Effects of visual gestural information on speaker localization among several speakers
Authors: Fujii Hiroyuki , Kakehi Kazuhiko
Published: October 2005

The phenomenon that sound localization is sometimes misled by the direction of a simultaneously presented visual object is known as the ventriloquist effect. The perceptual ability of making a correspondence between speech sound and the relevant speaker among several speakers was investigated using the ventriloquist effect. A speech sound of a 6-mora word was presented to a subject from one of the five loudspeakers located at intervals of 7.5 deg. At the same time two speakers’ images were presented by two CRT displays located at intervals of 30 deg in front of a subject. Four picture conditions based on the relationship between speech sound and visual gestural information were used: still (no motion)–still, still–unrelated (uttering a different word with the presented speech sound), still–related (uttering the same word with the presented speech sound), and unrelated–related. Subjects reported the location of the sound source, seeing the displayed speakers’ faces. The ventriloquist effect was observed only when the ‘‘related’’ picture was presented. A second experiment was conducted to examine the effect of target sound delay from visual gestural information. The results show that the ventriloquist effect was still observed up to the 300-ms delay condition, although the effect gradually decreased as the delay increased.
Voice quality conversion based on an ARX speech analysis–synthesis method and its application to the study of speaker individuality
Authors: Kasuya Hideki , Zhu Weizhong , Matsuda Masahiro , Yang Chang-Sheng
Published: October 2005

A novel pitch-synchronous analysis–synthesis method has been developed, in which a Rosenberg–Klatt (RK) model is used to simulate a glottal waveform of voiced speech, whereas an autoregressive with exogenous input (ARX) model is applied to represent the speech production process. Formant frequencies and bandwidths are automatically estimated from the ARX parameters, while the RK parameter values are obtained using the simulated annealing method. All the parameter values estimated can be used to re-synthesize speech based on the ARX equation. By modifying the parameter values estimated from an utterance, speech of various voice qualities can be synthesized. Three Japanese male adults uttered the same sentence |aoiueoie| (‘‘Say blue top’’ in English). The values of the formant frequency and bandwidth contours as well as the voicing source parameters of each of the speakers were systematically modified to simulate voice quality of the other speakers and a perceptual contribution of the parameters to the speaker individuality was quantitatively studied. It was found that dynamic characteristics of the first two formant frequencies were the most important and the glottal source parameters were of the least significance in describing individualities of the male speakers.
The effect of the phonological system in a language on speech perception for speaker variabilities
Authors: Kakehi Kazuhiko , Hirose Yuki , Dupoux Emmanuel , Mehler Jacques
Published: October 2005

Acoustic characteristics including vowel duration for the same speech sound may vary among individual speakers. The presented study reports that the influence of variability in physical duration of a vowel on speech perception differs depending on the phonological system of the language. Ten native speakers of each of three languages, namely Japanese (mora-time), French (syllable-time) and English (stress-timed) were employed. Ten sets of V1CuCV3 (V1,V3=/= [u]) sequences in which the duration of [u] was varied into six degrees (from full utterance to 0 pitch period of [u], where the steady state of [u] was reduced by two pitch periods) were created. The subjects were asked to judge whether each stimulus contained the interconsonantal [u]. For English and French speakers, the frequency of the judgments in which the [u] vowel was reported corresponded to the number of the pitch periods, whereas Japanese speakers consistently reported [u] even when its pitch periods were (almost) completely removed. The results can be explained by the fact that VCCV and VCuCV do not make a linguistic contrast in the Japanese phonological system, in which a consonant cluster is illegal and [u] is always epenthesized. These results thus suggest that perception of vowels varied in physical duration may be strongly influenced by the phonological system of the language that the listener employs.
Effects of context and speaking rate on liquid–stop sequences: A reassessment of traditional acoustic cues
Authors: Dainora Audra , Hemphill Rachel , Hirata Yukari , Olson Kenneth
Published: October 2005

The allophonic variation of liquids in American English prompted a study examining the findings of Mann [Percept. Psychophys. 28, 407–412 (1980)], Fowler etal . [Percept. Psychophys. 48, 559–570 (1990)], and Liberman [Speech (1996)], who used the F3 transition as the primary cue for synthesizing [da] vs [ga] following [al] and [ar]. The disyllables /al–da/, /al–ga/, /ar–da/, and /ar–ga/ were recorded in a carrier sentence by two male and two female speakers of midwestern English at three different speaking rates, and the spectra and durations of the liquids, stops, and vowels were analyzed. Acoustic analyses indicate structural variation: The F3 transitions of [da] and [ga] by themselves are not stable correlates in these contexts, notwithstanding data used in arguments for the perceptual invariance of articulatory gestures in liquid–stop sequences. Regularities were also found: The liquids systematically affect the F2 and F3 of the vowel in the following stop–vowel sequence, not only the onset value of F3. In addition, each speaker encoded segments in his/her own systematic way over variable rates, which extends Gay’s findings [J. Acoust. Soc. Am. 63, 223–230 (1978)] to tokens with coarticulatory effects. These data will help assess alternative acoustic cues in future perceptual experiments.
Perceptual coding of wideband audio signals: Basic principles and current applications
Authors: Bosi Marina
Published: October 2005

The need for a significant reduction in bit rate for wideband digital audio signal transmission and storage has led in the last few years to the development of psychoacoustics-based data compression techniques. In this approach, the audio frequency range is subdivided into sub-bands which are approximations of human auditory critical bands. The frequency representation of audio signals is accomplished using a filter-bank implemented as a time-to-frequency transform or as a sub-band filter. Frequency-domain masking properties of the human auditory system are exploited in order to maximize perceived fidelity of a steady-state signal at a given bit rate. In a similar way, temporal masking effects are very important in the bit-rate reduction process of transient signals. In this talk, the basic principles of perceptual audio coding will be reviewed. An adaptive transform coding technique will be presented in which both frequency-domain and temporal masking properties of human hearing are exploited during bit-rate reduction. Dolby’s current and future applications of this coding technology will be discussed.
High-efficiency, high-speed, 1-bit coding using generalized harmonic analysis
Authors: Yamasaki Yoshio , Kudo Shuji , Oikawa Yasuhiro , Endo Kazuo , Nishikawa Meisei , Ohta Hiroki
Published: October 2005

Usually in high-efficiency coding such as MPEG a regular digital signal whose sampling rate is from 32 to 48 kHz, and number of quantification bits from 12 to 16 bits are used. High-speed, 1-bit coding is proposed. Generalized harmonic analysis is simple. A sinusoid that minimizes the power of the residual waveform is found and extracted from the original waveform. The same procedure is carried out by substituting the weakest residual waveform for the original waveform. The frequency component can be extracted correctly. High-efficiency, high-speed, 1-bit coding using generalized harmonic analysis is reported here.
On the problems in applying Bell’s blind separation to real environments
Authors: Taniguchi Tomohiko , Yehia Hani , Takeda Kazuya , Itakura Fumitada
Published: October 2005

A blind separation method proposed by Bell et al. [Proc. ICASSP 95 (1995)] is a novel approach for source separation based only upon the assumption that the source signals are statistically independent of each other. In this paper, only simple computer-simulation results were described. The conditions of the experiments were extended and the method was evaluated under real conditions. In the first experiment, the SNRs of source signals are controlled by adding white Gaussian noise in order to clarify to what extent the source signals can be regarded as independent. The results clarify that SDR (i.e., signal-to-deviation ratio between the source and the separated signals) is proportional to the SNR of source signals when the SNR is below 20 dB, and the SDR saturates at 40 dB when the SNR is better than 20 dB. In the second experiment, the lengths of the signals are controlled to find the sufficient source signal length of processing. From the results it is found that the source signal length must be more than 2000 points to achieve an SDR of 30 dB.