bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in vocal fold vibration associated with intonation pattern
Authors: Kiritani Shigeru , Iwamoto Yoshitake , Imagawa Hiroshi , Niimi Seiji
Published: October 2005

Variation in the pattern of vocal fold vibration associated with changes in the prosodic conditions was observed by using a high-speed digital image recording system. A new image recording system (4500 frames per second with 256×256 pixels) combined with a flexible fiberscope and an image intensifier made it possible to record laryngeal images during running speech with better time and space resolution than the previous system. Vocal fold vibrations at an initial part and at a later part in the intonational phrases showed a difference in that the vibration at a later part tends to show shorter closed phase and slower closing movement, indicating weaker excitation in the voice source. It was also revealed that the cessation of vocal fold vibration at the end of an utterance generally takes place without the abductive movement. Abductive movement takes place shortly after the voicing cessation. It is speculated that the adduction of the vocal fold and/or the changes in the subglottal conditions are taking place for the voicing cessation which may be associated with the frequent sharp drop of the pitch at the end of the utterances.
Glottal characteristics of male speakers: Acoustic correlates and comparison with female data
Authors: Chuang Erika S. , Hanson Helen M.
Published: October 2005

Acoustic measurements related to glottal characteristics were made on recordings collected from ten male subjects. The waveforms and spectra of three nonhigh vowels /æ, ■, ε/ were analyzed to obtain acoustic parameters related to F1 bandwidth, open quotient, spectral tilt, and aspiration noise. Comparison was made with results for 22 female speakers [H. M. Hanson, J. Acoust. Soc. Am. 97, 3422(A) (1995)]. While there is considerable overlap across gender, the male data show lower average values and less interspeaker variation for all measures. In particular, for male speakers the amplitude of the first harmonic relative to that of F3 is 11 dB lower than for female speakers, suggesting that tilt is an important parameter for differentiating male and female voice qualities. These findings are consistent with fiberscopic studies which have shown that males tend to have a more complete glottal closure than females [Södersten and Lindestad, J. Speech Hear. Res. 33, 601–611 (1990)]. A consequence is that acoustic data for male speakers should show evidence of lower acoustic loss and spectral tilt than data for females. Further physiological and perceptual data are needed to verify the acoustic measures for the male speakers. [Work supported by NIH Grants No. DC00075 and No. DC00205-02.]
A shape-based approach to vocal tract area function estimation
Authors: Tiede Mark K. , Yehia Hani
Published: October 2005

In default of a method for obtaining dynamic/time-varying 3-D vocal tract data, it remains the case that the midsagittal profile provides the best characterization of tract articulators. For this reason articulatory approaches to speech synthesis typically model the vocal tract as a series of concatenated tubes whose cross-sectional areas are related by some heuristic (the area function) to the midsagittal cross dimensions. But while areas alone are adequate for lower formants, accurate modeling of higher frequencies requires access to details of tract morphology. Previous work based on MRI volume parametrization from a single subject [Tiede et al., Proc. ETRW-SPM, 41–44 (1996)] has demonstrated the feasibility of recovering correlated cross-sectional shapes from the midsagittal profile alone. In the current study this approach is extended to analysis of four English and four Japanese subjects (five MRI-scanned vowels per subject). The results show that characteristic tract shapes for vowels can be recovered from a small and highly constrained set of parameters. Since area is easily recoverable from such shapes, this approach can be used to augment standard area function techniques.
Accurate measurement of three-dimensional shapes of a vocal tract and a dental crown using magnetic resonance imaging: Japanese fricative consonants
Authors: Niikawa Takuya , Matsumura Masafumi , Tachimura Takashi , Wada Takeshi , Shimizu Koji , Hashimoto Yasuji
Published: October 2005

Three-dimensional MR images of the vocal tract of three adult males were obtained during steady-state production of the Japanese fricatives /s/, /sh/, and /shu/. MR images of dental crowns containing a small amount of water were obtained using a dental crown plate which was shaped so as to attach tightly to the subject’s dental crown by thermoforming which contained a contrast medium for MR imaging. A computer algorithm based on gray level interpolation and threshold operation for air–tissue boundary tracing of arbitrary sections of the vocal tract taken from axial and coronal MR images were proposed. Images of arbitrary sections of the vocal tract were reconstructed from 3-D MR images using gray level interpolation based on the sampling theorem. Gray level thresholds were computed from the gray levels at points on the air–tissue border. The boundary tracing error of the dental crowns from the 3-D MR images was less than 5.7%. The 3-D shape and area function of the vocal tract during production of the Japanese fricatives /s/, /sh/, and /shu/ were obtained.
Approximate vocal tract shape invariance without vocal tract shape targets
Authors: Guenther Frank H. , Hampson Michelle , Micci Barreca Daniele
Published: October 2005

Under normal conditions, the vocal tract shapes (postures) used by speakers to produce vowels appear to represent only a small subset of the possible shapes that could be used. This seems to suggest that speakers use postural targets (e.g., constriction targets) when planning speech movements. However, postural targets limit the motor equivalent capabilities of a movement controller. An alternative explanation for the approximate postural invariance maintains a high degree of motor equivalence by utilizing only acoustic/perceptual targets and transforming trajectories planned in acoustic/perceptual space into articulator movements through a directional mapping with a ‘‘postural relaxation’’ component. The postural relaxation component biases movements toward more central articulator configurations. Examples of this kind of controller include robotics techniques that utilize a Jacobian pseudoinverse in combination with null space movements formed using an orthogonal projection operator. The current work investigates how such a directional mapping can be learned by a biological motor system during babbling and how it can lead to postural invariance. Simulations of the DIVA model of speech acquisition and production utilizing an adaptive postural relaxation scheme verify the property of approximate postural invariance despite using no postural targets in the planning process. [Work supported by NIH and the Sloan Foundation.]
Timing of articulatory and acoustic targets—Evidence from electropalatography
Authors: Javkin Hector R. , Kibre Nicholas , Youdelman Karen
Published: October 2005

The synthesis of tongue-contact patterns analogous to those measured by electropalatography (EPG) has been undertaken both to provide models for the speech training of deaf children and to improve our understanding of articulatory gestures. [Javkin et al., ESCA Workshop on Speech & Language Technology for Disabled Persons, Stockholm, June 1993, 137–140; ICSLP S32-5.1 (1959–1962)]. In previous studies of other articulatory gestures [C. Browman, LabPhon3, UCLA, 1991], it was found that articulatory targets are not reached at the same time as the speech acoustic signal. In our present EPG study, a similar effect is found for tongue–palate contact—contact continues to increase after an acoustic target has been reached. For example, full frication for /s/ is achieved before the closing gesture is completed, and the decay of frication occurs after the release gesture begins. Even in consonants of relatively long duration (150 ms) from disyllabic words produced in isolation, there is, in effect, no steady-state contact—the release begins as soon as the closure is completed. This has led to adjustments in timing for palatographic synthesis derived from a standard text-to-speech system.
Landmark selection for cross-mapping muscle anatomy and volumetric images of the human tongue
Authors: Wu Chao-Min , Wilhelms-Tricarico Reiner
Published: October 2005

The main objective of this work is to obtain reliable and detailed anatomical information for developing a quantitative 3-D tongue model. This work introduces a strategy for defining a set of landmark points in reference to a general 3-D representation of tongue structure. The landmarks define locations of anatomical significance that have identifiable geometric coordinates. They constitute common reference points for a mathematical mapping between any pair of data sets and indicate the anatomical correspondence, or homology, between the data sets. The integration of different data sets of the human tongue is based on this correspondence, and it is achieved by a method of nonuniform geometrical transformation (thin-plate spline mapping). We show the feasibility of these methods by mapping from muscle anatomy, according to a detailed hand-drawn dissection study [K. Miyawaki, Ann. Bul. RILP, Univ. Tokyo 8, 23–50 (1974)], against atlas images from freshly deep-frozen samples (Visible Man data) and MRI head scans of living subjects making a vowel articulatory gesture. As the result of this exercise, we have produced a tongue portion of the Visible Man data with muscle fiber direction identified. [Work supported in part by NSF grant RF 729550 and ATR/MIC Labs.]
Acoustic and aerodynamic studies of Korean vowel devoicing
Authors: Kim Hyun-Gi , Niimi Seiji
Published: October 2005

Previous studies have shown that Korean high vowels are highly likely to be devoiced between fricatives and aspirated consonants based on acoustic and EMG data [Hirose (1974); Kim et al. (1993); Jun and Beckman (1993, 1994)]. In this paper, intraoral air pressure during vowel devoicing was examined together with acoustic data. Intraoral pressure was collected by inserting a sense tube Gaeltec S7b through the nostrils to the oropharynx, and the data were measured using the high-speed speech analysis system at RILP, Univ. of Tokyo. Three native Korean speakers repeated test words [siC] in a phrase at a normal and fast rate. The results show that there are four types of intraoral air pressure configurations: (1) completely devoiced vowel—a single peak rising during [s] and falling after C; (2) completely voiced vowel—a small peak during [s] and a fall during [i] and a bigger peak during C; (3) partially devoiced vowel, I—a single peak with a plateau or shoulder during [i]; (4) partially devoiced vowel, II—a high peak from [s] to C with a few quasiperiodic waves during [i]. More aerodynamic measurements based on EGG, airflow, and oral air pressure will be examined to understand the glottal gestures during the partially devoiced vowels.
Motor control information recovering using a target-based model of articulatory trajectory generation
Authors: Lœvenbruck Hélène , Perrier Pascal
Published: October 2005

A quantitative target-based model of articulatory trajectory formation in speech is proposed here, where for a same vowel sequence, equilibrium targets are assumed to remain identical, independent of speaking rate and stress; only their timing and the muscle cocontraction level are adjusted following prosodic requirements. This model is used to examine how relevant motor control information could be extracted from the acoustic signal to help identifying vowels by providing clues on the stress or rate conditions. Sequences [iai] and [iεi] under three prosodic conditions (slow stressed —ideal condition—, slow unstressed and fast stressed —reduced conditions—) are analyzed. Equilibrium targets are imposed as the actual positions are reached by the tongue body under the ideal condition. The cocontraction level and the timing of the commands are inferred using a two-step inversion procedure: from the acoustic signal to tongue body trajectories then to motor commands. It is shown that at a given speaking rate, stressed sequences are produced with either longer transitions or a higher cocontraction level, or both. To assess the reliability of inferred motor commands, the model’s sensitivity is evaluated around the inferred temporal and cocontraction patterns, and perceptual tests are run on synthetic stimuli.
Investigating the ‘‘trough:’’ Vowel dynamics and aerodynamics
Authors: Engstrand Olle , McAllister Robert , Lindblom Björn
Published: October 2005

Articulatory coordination in vowel–consonant–vowel utterances (V=/i a/, C=/p b/) was studied in 5 Swedish, 3 English, 2 German, and 3 French speakers. Electropalatographic records showed that the amount of transconsonantal V-to-V coarticulation was greater in German and French than in Swedish and English. For the symmetrical utterances /ipi/ and /ibi/, the EPG patterns displayed a marked ‘‘trough’’ (a temporary reduction of tongue height) associated with the stop closure in the Swedish and English, but not in the German and French speakers; the Swedish and English trough patterns were, however, differently timed. These observations are consistent with dynamic vowel features characteristic of the respective languages. In a second experiment, using a wider voice onset time range, three Swedish speakers produced words containing CV syllables (C=/p b t d k g/, V=/i o/ a ■ u/). VOT was controlled in terms of voicing, stress, word length, and position in the word. Formant data showed that the amount of F2 locus-to-target assimilation decreased as a function of voicing lag. This suggests that aerodynamic factors associated with aspiration affect anticipatory coarticulation patterns; specifically, it may affect trough patterns in symmetrical VCVs.
The relationship between lip shapes and acoustical characteristics during speech
Authors: Mori Keisuke , Sonoda Yorinobu
Published: October 2005

This paper studied recognition tests jointly using articulatory behavior of lips and sound pattern during speech. Lip movements were monitored by using a high-speed video system with a frame rate of 5 ms. At the same time, speech sounds were recorded on a digital recorder. Two parameters, lip opening area and width of lip edges, were obtained as a time pattern from approximated contours with a fourth-degree polynomial [ICSLP90, 11.6.1 (1990)]. Recognition tests were examined by using acoustical parameters of three formant patterns (F1, F2, andF 3), as well as articulatory parameters. The speech materials used in the paper were nonsense words of symmetrical form |eCVCe| (V: a, i, u, e, o; C: p, b, m) from four males. A neural network was used for recognition tests of identifying (1) morae (CV), (2) vowel (V), and (3) consonant (C) from the time patterns of articulatory movements and acoustical sounds in –CVC–. The recognition rate of vowels using both articulatory and acoustical patterns was 91%, and it was higher than that using these patterns separately. In recognition of the consonant test, the score uisng the shape pattern was 96%, and it was higher than that using both acoustical and shape patterns.
Speech compensations to palatal modifications
Authors: Munhall Kevin G.
Published: October 2005

Oral morphology varies significantly between individuals and must be taken into account during speech development. The present study examines adaptations to a modification of the shape of the alveolar region of the palate. Adult subjects were fitted with artificial palate prostheses and acoustic and kinematic variables were measured during the production of /s/. Recordings were made preceding and immediately following the insertion of the palate. The key feature of the study is that the post-insertion training is controlled. Initially, subjects practice only static /s/. Following this, different target words are practiced in sequence. OPTOTRAK was used to make kinematic measures of the movements of the lips and jaw. Analyses of the centroid, skewness, and kurtosis of the spectral distributions of the /s/ acoustics were carried out. Preliminary results indicate that there are significant changes in the spectra of the fricatives following insertion of the artificial palate and that adaptations require extended training. Further, compensations appear to vary with phonetic environment. Results will be discussed in relation to models of coarticulation.
Articulatory effects of vowel context on fricatives: A magnetic resonance image study
Authors: Shadle Christine H. , Tiede Mark , Masaki Shinobu , Shimada Yasuhiro , Fujimoto Ichiro
Published: October 2005

Magnetic resonance imaging (MRI) is increasingly used in speech production research, particularly to obtain three-dimensional images of sustainable sounds such as fricatives or vowels. However, acoustic studies of fricatives [Shadle et al., Proc. ETRW, 193–196 (1996)] have shown that the spectral shape varies with vowel context, with the amount of variation depending on the fricative. This study, therefore, uses MRI to study the articulatory correlates of vowel context effects on fricatives. Two subjects (male French, female American English) for whom a large acoustic, aerodynamic, and articulatory database of fricatives already existed, were studied. Three different imaging methods were used that varied in acquisition time, image quality, and image extent: midsagittal turbo-flash (2 s), midsagittal spin-echo (15 s), and full coronal and axial spin-echo scans (approx. 2 min each). The subjects uttered the fricatives [f, θ, s, ∫] in vowel contexts [a, i, u]. Results indicate that not only are vowel context effects preserved in the longer duration images, they are often heightened. [f] showed the greatest variation in configuration with vowel context. Comparison to acoustic results and other MRI studies will be presented. [Work supported by ATR HIP Laboratories, while the first author was an invited researcher at ATR.]
An MRI and EPG examination of /r/ and /l/
Authors: Stone Maureen , Ong Darryl , Lundberg Andrew
Published: October 2005

This study characterized airway shapes for retroflex /r/ and /l/ reconstructed from multiplanar MR images, and compared them to acoustical and EPG data. Observing the production gestures in light of the sounds’ acoustic similarities were of interest. The results indicated that the /l/ and /r/ airways had remarkably similar area functions with small pharyngeal volumes and large oral volumes. At the tongue tip there was much closer tongue–palate contact for the /r/ than the /l/ and an anterior cavity for /r/. The similarities of general shape may account for the similar F1 and F2 frequencies. The extra anterior cavity and elevated top for /r/ may affect the F3 difference between the sounds. EPG/acoustic data were collected for bunched and retroflex /r/. The EPG data confirmed the /l/ and /r/ differences and distinguished between the two /r/’s. Palatal contact for the bunched /r/ was lateral and began at the highest point of the tongue and posteriorly (last four rows). For the retroflex /r/ the contact was posterior to the bunched /r/ (last two rows) and was made with the tongue margins posterior to the freestanding tip. Acoustically, bunched /r/ had a higher F3. [Work supported by NIH.]
Palato-lingual contact patterns during voiced and unvoiced consonant production
Authors: Yoshioka Hirohide , Murase Shinobu , Uematsu Mikiko
Published: October 2005

The timing of the initiation and cessation of vocal fold vibrations characterizes the voiced and unvoiced stops. The results of perceptual experiments, however, have revealed that other cues, such as the duration of preceding vowels, the patterns of the formant transitions in the following vowels, and the period of stop closures, may play important roles in differentiating these cognates. Therefore, the present study is to further investigate the role of the tongue articulatory movements during voiced and unvoiced consonant production in Japanese. Three normal Japanese speakers served as the subjects. The palato-lingual contact patterns during intervocalic consonant productions were recorded using dynamic electropalatography. The results show that the area and duration of the palato-lingual contact are clearly larger and longer during voiceless stop productions than those during voiced cognate productions. As for fricative consonant productions, the opening of apical area during voiceless fricative production is wide and stable, while the pattern of maximal contact area is unstable. In addition, those subjects were further requested to produce same utterance lists in whispered speech. The results also supported these findings despite the lack of normal vocal fold vibrations.
Computer modeling of the production of ejectives using aerodynamic and acoustic data
Authors: MacEachern Margaret R.
Published: October 2005

The articulation of ejective segments has not been extensively studied. In this study, oral pressure and oral flow data were collected during the production of aspirated and ejective stop consonants by three linguists. Preliminary results indicate that the oral pressure of ejectives is several times greater than that of aspirated stops. Characteristic differences between ejectives and aspirated stops are also apparent in pressure rise-to-peak, pressure fall-to-gauge, and oral flow measurements. The finding that ejectives show much greater oral pressures than do aspirated stops is in accord with the reports of earlier researchers for Tigrinya [Fre Woldu, Reports from Uppsala Dept. of Linguist. 13, 1985], several Quichean languages [Pinkerton, Ohala, and Jaeger (Eds.), 125–139 (1986)], and Montana Salish [Flemming et al., UCLA Work. Papers Phon. 87, 1–34 (1994)]. The preliminary results are a variance with those found for Tigrinya speakers by Kingston (1985) [Ph.D. dissertation, UC Berkeley]. That study, which includes a computer model of ejective production, produced several unexpected findings. The data from this study, which may be more representative of ejectives cross linguistically, will be used in analysis by synthesis using a similar computer model.
Development of an articulatory measuring system by using magnetometer and optical sensors
Authors: Ogata Kohichi , Sonoda Yorinobu
Published: October 2005

This paper introduces a useful measuring system for monitoring articulatory movements. The system is made up of magnetometer and optical sensor units. The magnetometer unit consists of sensors having two amorphous alloy cores and small permanent magnetic rods, which are attached to the tongue surface as pellets. A measuring principle is based on a change in the intensity of the magnetic fields related to distances between the rods and sensors. On the detection of the rods’ positions, tilting and lateral movements of the rods on the tongue surface cause measurement errors, and such troublesome movements are serious problems in the magnetic sensing system using similar principles. The system developed here is able to reduce these errors with symmetrical arrangements of magnetometer sensors around the subject’s jaw. The optical sensor, which was previously developed, consists of a position-sensitive device (PSD) which detects positions of the light-emitting diodes (LEDs) which are attached to the lips, jaw, etc., as markers. As a result of quick response characteristics of the system, dynamical articulatory movements can be observed during speech production.
Perceptual effects of speaking with pellets on the articulators: An x-ray microbeam study
Authors: Weismer Gary , Bunton Kate
Published: October 2005

A companion paper (‘‘Acoustic effects of speaking with pellets on the articulators: An x-ray microbeam study’’) will report on the effects of pellets on versus pellets off on spectral and temporal characteristics of a sentence-level utterance. In the present paper, the perceptual effects of speaking with pellets on the articulators will be reported. At least 20% of the task inventory recorded at the University of Wisconsin x-ray microbeam facility were collected without pellets. Multiple repetitions of a single utterance, recorded by 21 speakers with and without pellets attached to the articulators, were digitized and then output to tape in random order. Several different types of perceptual judgments were collected, including: (1) a dichotomous ‘‘does the speaker have something in their mouth (or not)’’ judgment; (2) scalings of perceptual dimensions such as ‘‘articulatory precision;’’ and (3) overall levels of utterance normalcy. Particular attention will be devoted to those speakers whose acoustic results (presented in a companion paper) showed a strong effect of the pellets. [Work supported by DC00820.]
Micropower radar measurements of human vocal articulator motions
Authors: Burnett Gregory , Holzrichter John F. , Ng Lawrence C. , Leonard Rebecca , Lea Wayne A.
Published: October 2005

A major impediment to speech research is the lack of readily available scientific means of measuring vocal tract motion while a subject is speaking. Several experiments have been conducted recently using the micropower radars, invented at the Lawrence Livermore National Laboratory (LLNL), to detect speech articulator motions including vocal folds, lips, and tongue with considerable successes. In order to establish the scientific accuracy of the articulator measurements, it is important to quantify the radar returns from known tissue interface positions. One of the most important articulatory systems is the glottal structure which defines the vocalized excitation function of human speech. This structure can now be measured in real time, and therefore one can describe the excitation function in real time for each speech time frame. Calibration experiments have been conducted to relate the radar return signals to glottal opening, as well as airflow and air pressure. These results will be presented in detail. It is believed that LLNL’s micropower radars could be the basic component used in building a low-cost, noninvasive instrument for innovative speech science research.
Uses of micropower radars for speech coding and applications
Authors: Holzrichter John F. , Lea Wayne A. , Ng Lawrence C. , Burnett Gregory
Published: October 2005

It has recently become possible to measure the positions and motions of the human speech organs, as speech is being articulated, by using micropower radars in a noninvasive manner. Using these instruments the vocalized excitation function of human speech is measured and thereby the transfer function of each constant vocalized speech unit is obtained by deconvolving the output acoustic pressure from the input excitation function. In addition, the positions of the tongue, lips, jaw, velum, and glottal tissues are measured for each speech unit. Using these data, very descriptive feature vectors for each acoustic speech unit were able to be formed. It is believed that these new data, in conjunction with presently obtained acoustic data, will lead to more efficient speech coding, recognition, synthesis, telephony, and prosthesis.
Treatment for the aging voice: Acoustic, aerodynamic, and electromyographic changes
Authors: Ramig Lorraine Olson , Baker Kristin , Luschei Erich
Published: October 2005

The purpose of the present investigation was to evaluate changes associated with vocal aging before and after an intensive program of voice treatment. Three aged (68–70 years) individuals (two men and one woman) each participated in three pre-treatment and two post-treatment recording sessions. All subjects received 16 sessions of voice treatment (LSVT) within one month. The LSVT has been designed to increase vocal loudness and functional oral communication through maximizing phonatory efficiency and previously has been documented to be effective in treating speech and voice disorders in patients with Parkinson’s disease [Ramig et al., J. Speech Hear. Res. 38, 1232–1251 (1995)]. Acoustic, videostroboscopic, aerodynamic, electromyographic, and perceptual data will be discussed in relation to treatment-related changes in sound-pressure level in these aged subjects. [Work supported by NIH.]
Transformation from normal to twang and sob vocal qualities
Authors: Long Russel , Lange Robert , Wong Darrell , Story Brad , Titze Ingo
Published: October 2005

Vocal qualities such as twang and sob are produced when the speaker manipulates the pharyngeal and laryngeal regions of the throat. The laryngeal manipulations involve adjustments to the larynx with respect to mode of vibration and position in the throat. The epilaryngeal and pharyngeal regions of the vocal tract are then constricted or expanded to obtain the appropriate quality. In this study an attempt is made to simulate these qualities by analyzing a subject attempting a normal to affected-quality transformation. A videolaryngoscopic examination and LPC analysis of steady-state vowels was used to parametrize the changes occurring in the articulation. These changes were assumed to apply to sentence level speech. A glottal-pulse driven linear prediction model was then used to modify sentence level speech. The results suggest that appropriate adjustments in formant locations (via rotations in the pole-zero domain) can evoke the twang and sob qualities. [Work supported by NIH Grant DCO2532-01.]
Effects of higher-order modes on sound radiation characteristics at the mouth opening
Authors: Motoki Kunitoshi , Miki Nobuhiro
Published: October 2005

The influence of higher-order modes in vocal tracts resulting from the speech radiation process are investigated based on acoustic measurement. Though a real vocal tract has a complicated figuration, a uniform rectangular tube was used as a specimen for the theoretical simplicity of wave propagation. The higher-order modes were intentionally excited at one end of the tube, and were radiated from the other end of the tube that was mounted flush with a plane baffle surface. Spatial distributions of sound pressure in the vicinity of the radiation region were measured precisely. As the result, the measured distributions of sound pressure show good agreement with those of the well-known ideal piston model below the first cutoff frequency. Above this frequency, however, quite complicated distributions appear even outside the tube. Distributions of particle velocity and acoustic intensity are also introduced to visualize the acoustic field for higher frequencies. These visualizations suggest that in the case of potential excitation of higher-order modes in the vocal tract, a radiation impedance derived from the piston model should not be used as a boundary condition for the speech radiation process.
A transmission-line model of the lateral approximants
Authors: Bangayan Philbert , Alwan Abeer , Narayanan Shrikanth
Published: October 2005

In this paper, a transmission-line model of the dark and light allophones of the lateral approximant /l/ is presented. Modeling was based on vocal-tract area functions derived from MRI data of four speakers of American English (two males and two females). The transmission line consisted of 50–60 sections; each T-section is represented by four components (R, L, C, and G). Different topologies in which the vocal tract was modeled with and without side branches were investigated. Simulations were performed using the analog-circuit simulator HSPICE [Rael etal ., J. Acoust. Soc. Am. 97, 3245(A) (1995)]. Small-signal analysis was used to determine the formant frequencies from the frequency response of the transmission-line model. The articulatory-to-acoustic mappings in /l/ for all four speakers will be discussed in detail. [Work supported by NSF Grant No. IRI-95-03089.]
A maximum likelihood approach to estimating speech articulator positions from speech acoustics
Authors: Hogden John E.
Published: October 2005

An algorithm called maximum likelihood continuity mapping (MALCOM) will be presented. MALCOM recovers the positions of the tongue, jaw, and lips from measurements of the sound-pressure waveform of speech. Unlike other techniques for recovering articulator positions from speech, MALCOM does not require training on measured or modeled articulator positions, and MALCOM does not rely on any particular model of sound propagation through the vocal tract. The algorithm categorizes short-time windows of speech into a finite number of sound types, and assumes the probability of using any articulator position to produce a given sound type can be described by a parametrized probability density function. MALCOM uses maximum likelihood estimation techniques to: (1) find the most likely smooth articulator path given a speech sample and a set of probability density functions (one density function for each sound type); and (2) change the parameters of the probability density functions to better account for the data. The data set used for evaluating the continuity mapping algorithm is comprised of simultaneously collected articulator and acoustic measurements made using an electromagnetic midsagittal articulometer on a human subject. Comparisons between measured articulator positions and those recovered using continuity mapping will be presented.
Experimental demonstration of an acoustic time reversal mirror in the ocean
Authors: Kuperman William A. , Hodgkiss William S. , Song Hee C. , Akal T. , Ferla C. , Jackson Darrell R.
Published: October 2005

An experiment conducted in the Mediterranean Sea in April 1996 demonstrated that a time reversal mirror (or phase conjugate array) can be implemented to spatially and temporally refocus an incident acoustic field back to its origin. The experiment utilized a vertical source–receiver array (SRA) spanning 77 m of a 125-m water column with 20 sources and receivers and a single source/receiver transponder (SRT) co-located in range with another vertical receive array (VRA) of 46 elements spanning 90 m of a 145-m water column located 6.5 km from the SRA. Phase conjugation was implemented by transmitting a 50-ms pulse from the SRT to the SRA, digitizing the received signal and retransmitting the time-reversed signals from all the sources of the SRA. The retransmitted signal was then received at the VRA. An assortment of runs were made to examine the structure of the focal point region and the temporal stability of the process. The phase conjugation process was extremely robust and stable. There was also excellent agreement between experiment and theory.
Retrofocusing of a time reversing acoustic array in shallow-water random media
Authors: Khosla Sunny R. , Dowling David R.
Published: October 2005

A time reversing or phase conjugate array operating in a random medium has been shown to focus acoustic radiation better than an equivalent array operating in a nonrefractive medium, making such arrays attractive for a large class of underwater acoustic problems. The present work extends this result to include the lifetime of the array’s focus, and shallow-water random refraction. Analytic predictions of focal properties, based on the parabolic approximation to the second moment of the Green’s function connecting the source with the array, are made for acoustic propagation through an unbounded dynamic random medium. The necessary projected autocorrelation function for the spatial and temporal evolution of the acoustic medium has been constructed from available oceanographic shallow-water fluctuation statistics. Focus size and focus lifetime are predicted to depend on acoustic frequency, source–array range, and array size. Focus lifetime predictions suggest that there is substantial opportunity for retrofocusing application of this technology. Influence of the ocean surface and deterministic water column variations will be addressed in future research.
Application of multifrequency inversion methods to obtain seabed properties from broadband reverberation data
Authors: Gerstoft Peter , Ellis Dale D.
Published: October 2005

The determination of scattering strengths in shallow water is difficult due to multipath effects. A method is described that is based on global inversion of reverberation data, which allows both the bottom scattering strength and geoacoustic parameters (bottom loss) to be determined simultaneously. Ellis [J. Acoust. Soc. Am. 97, 2804 (1995)] has described a computationally efficient reverberation model based on normal modes and ray-mode analogies. This is combined with the global inversion method of Gerstoft [J. Acoust. Soc. Am. 95, 770 (1994)]. Using broadband reverberation data from a shallow-water site north of Elba in the Mediterranean Sea, bottom scattering strengths and bottom sound speeds have been extracted. The reliability of estimating other environmental parameters is also investigated. By using the data from all frequencies simultaneously in the inversion, the stability of the estimates is significantly improved.
Inversions for nearshore seafloor geoacoustic parameters from source tow data
Authors: Hodgkiss William S. , D’Spain Gerald L. , Kuperman William A. , Olivera R. Martin , Murray James J.
Published: October 2005

During the MPL adaptive beach monitoring experiment conducted in April–June 1995 off Camp Pendleton (north of San Diego, CA), a series of controlled source tows were performed in the nearshore region in 10–20 m of water. Four tones at 95, 145, 195, and 370 Hz were broadcast simultaneously by the source which was 5 m deep and received by two 120-m-long, 64-element, horizontal bottom hydrophone arrays (approximately parallel and perpendicular to the beach) located 3.4 km offshore in 20 m of water. The results from three approaches to carrying out inversions for nearshore seafloor geoacoustic parameters are compared. The first makes use of a simple analytical expression for waveguide effective depth which incorporates the interference wavelength of the first two modes. The second is a wave-number perturbation approach using source tow data from both real and synthetic array apertures. Finally, the third is a full-field inversion for seafloor geoacoustic parameters. [Work supported by ONR, Code 32.]
Algorithms for matched-field inversion: Comparison and performance
Authors: Ozard John M. , Zala Cedric A.
Published: October 2005

Successful MFP requires a knowledge of the bathymetry and the existence of a suitable geoacoustic model for the sound-speed profile and the bottom characteristics. In practice, these parameters are known only approximately, and it is desirable to obtain more accurate estimates to improve the effectiveness of MFP. This aim may be achieved through matched-field inversion (MFI) of data obtained using a source at a series of known locations in the environment. Development of effective inversion procedures requires the use of appropriate numerical optimization techniques suited to the nature of the multimodal multidimensional matching functional to be optimized. This study examines several approaches to global optimization, including simulated annealing, a genetic algorithm, and a combined random search/local optimization approach. Results comparing these approaches were obtained using a model multimodal function with provision for correlated parameters; the performance of several local optimization algorithms was also compared using this model function. For the case of a realistic range-independent waveguide, the functional interactions between several sensitive model parameters were examined by generating 2-D plots of the matching function as a function of selected parameter pairs, using the normal mode program ORCA to generate the fields for matching. Results of inversion for range-dependent environments using this system will be presented and discussed.
Acoustic wave inversion using incomplete data in a stratified ocean
Authors: Xu Yongzhi
Published: October 2005

Acoustic waves scattered by an object in a stratified ocean are much different from acoustic waves in a homogeneous medium. In a stratified medium, the scattered energy is not spread out spherically. Therefore, the scattered far field consists of two components: the free-wave far field and the guided-wave far field. In many cases only the free-wave far field or only the guided-wave far field can be measured. This research concerns the problems of determining the shape of submersible from the incomplete far-field data. It has been found that the choice of incident waves is very important in determination of the shape of the unknown object from only the free-wave far field or only the guided-wave far field. Computational results demonstrate the importance of selection of incident waves. Sufficient conditions on incident waves are found for uniqueness in shape determination using incomplete data. [This research was supported in part by the NSF Grant No. BES-9402539, the UTC Summer Grant, and the China–Cornell Fellowship.]
Geoacoustic inversion using fish sounds
Authors: D’Spain Gerald L. , Kuperman William A. , Berger Lewis P. , Hodgkiss William S.
Published: October 2005

During a recent near-surf-zone experiment, the underwater acoustic noise field was dominated by biological sounds over the 50-Hz to 10-kHz band. At night, members of the croaker (Sciaenidae) family migrated from the surf zone out to the 20-m water, where two bottom hydrophone arrays were located. Often during the night, individual vocalizing fish came within several meters of an array element so that the fish’s sequence of 7–13 knocks, each with peak-to-peak source levels of about 160 dB re: 1 μPa @ 1 m, was clearly discernible above the background din. The arrivals from some of these knocks display low-frequency (around 60 Hz) oscillatory tails due to excitation of interface waves at the ocean bottom. These Scholte waves have phase velocities around 110 m/s and a group velocity near 30 m/s. Using adjacent array elements to locate the fish at each knock, its movement over the sequence creates a synthetic aperture that is used in inversion for the shear wave velocity in the uppermost part of the ocean bottom. [Work supported by ONR, Code 32.]
On the anomalous resonance effect caused by shallow-water solitons
Authors: Chin-Bing Stanley A. , King David B. , Warn Varnas Alex
Published: October 2005

Zhou et al. [J. Acoust. Soc. Am. 90, 2042–2054 (1987)] have hypothesized that mode conversion due to large-amplitude shallow-water internal waves (solitons) could explain the anomalous transmission loss observed in acoustic data taken in the Yellow Sea. Numerical experiments had been performed that substantiated their hypothesis [Chin-Bing et al., Math. Model. Sci. Comput. 4 (1994); King et al., Theor. Comput. Acoust. 2, 793–807 (1994)]. It is also found that the effect is most prominent when there is strong coupling between the lower-order propagation modes and the very lossy, higher-order modes. In reaching these conclusions, both groups assumed an idealized sinusoidal soliton structure. The analysis has recently been repeated using a soliton sound-speed structure more characteristic of what is found in straits. Results will be presented that show the similarities and differences in anomalous transmission loss for the realistic and the idealized sinusoidal soliton. [Work supported by ONR/NRL and by a Federal High Performance Computing DoD grant.]
Mode-coupling behavior in continental-shelf internal solitary waves
Authors: Preisig James C. , Duda Timothy F.
Published: October 2005

Acoustic propagation through continental-shelf internal solitary waves (ISWs) is analyzed using the framework of acoustic modes. Propagation is modeled using both a numerical parabolic equation solution and a simple sharp interface approximation (SIA) matrix formulation. Analytic expressions for mode-coupling strength are also considered. In the coupled-mode (nonadiabatic) regime there is close agreement between the two sets of numerical results. The boundary between adiabatic and coupled propagation, and the relative propensity for various mode pairs to couple, are well predicted by analytic theory. Analysis of the SIA expressions shows that relative mode phases are the dominant parameters governing mode-coupling activity in the nonadiabatic regime. The roles of the ISW amplitude and horizontal scale in determining the relative phasings is examined. Using the phasing results and mode refraction analysis, the traditional two-dimensional acoustic model is extended to handle mode propagation through ISWs when the incident acoustic field is oblique to the ISW wavefront. The extension is valid for a wide range of incidence angles. [Work supported by ONR.]
Acoustic scintillations in the Straits of Florida
Authors: Tappert F. D. , Tang X. , Creamer D. B.
Published: October 2005

Using the UMPE acoustic model, Monte Carlo numerical studies of sound propagation in a realistic shallow-water environment that simulates the Straits of Florida, including internal wave fluctuations and bottom roughness, have been performed. Results show that the sound intensity at distant receivers scintillates dramatically. The acoustic scintillation index, SI=〈I2〉/〈I〉2−1, increases exponentially with propagation range and is significantly greater than unity at ranges beyond about 10 km. This result supports the recent theoretical prediction of Creamer [J. Acoust. Soc. Am. 99, 2825–2836 (1996)]. Statistical analyses show that the distribution of intensity of the random wave fields saturates to the expected Rayleigh distribution with SI=1 at short range (about 5 km) due to multipath effects, and then SI increases exponentially and the intensity distribution approaches a log-normal distribution to an excellent approximation. This ‘‘supersaturation’’ effect is found to be universal at long ranges in waveguides having lossy boundaries, and is believed to have fundamental implications for statistical physics. [Work supported by ONR.]
Obtaining the ocean index of refraction spectrum from the acoustic amplitude fluctuations
Authors: Ewart Terry E. , Reynolds Stephen A. , Rouseff Daniel
Published: October 2005

Ewart and Reynolds [Wave Propagation in Random Media (Scintillation), edited by Tatarski, Ishimaru, and Zavorotny (SPIE, Bellingham, WA, 1993), pp. 100–123] provide a convincing comparison between the ocean spectral model determined from a stochastic inverse using the acoustic phase spectrum (measured in the Mid-ocean Acoustic Transmission Experiment) and the same model derived from oceanographic data. The success of using the acoustic phase for such inverses is based on the high accuracy of Rytov theory to predict the phase spectrum. Accurate measurement of the acoustic phases (travel times) requires fixed sources and receivers, an experimental complication. If it were possible to use Rytov theory for the amplitude fluctuations, the experiment complexity is much reduced and simpler moorings could be used. In this talk results are presented from a study of the viability of this approach using numerical simulations of propagation through internal waves to a vertical array of receivers. With the only requirement being applicability of the Rytov approximation, two-dimensional (depth/time) correlations of the oceanographic model are obtained by stochastic inversion and compared to the input internal wave model. The importance of this result to augmenting oceanographic measurements, and a discussion of the future possibilities, are presented. [Work supported by ONR.]