bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of red blood cells using inverse acoustic scattering
Authors: Chen Xucai , Apfel Robert E.
Published: October 2005

Three mechanical parameters—volume, compressibility, and density—of human erythrocytes (red blood cells) are measured. The experimental apparatus consists of two confocally positioned high-frequency acoustic transducers and an on-line Coulter-type volume sensing zone [J Acoust. Soc. Am. Suppl. 1 84, S163 (1988)]. Different scattering theories are used to invert the experimental data. Normal red blood cells suspended in saline solutions of varying salinity are tested. A red blood cell is modeled as an immiscible mixture of a protein and saline solution, and perfect mixture laws for compressibility and density as functions of a protein fraction for such a mixture are derived. The mean corpuscular hemoglobin concentration is then calculated from the compressibility and density data. Abnormal red blood cells, e.g., red blood cells from anemic patients, are also tested, and results are correlated to the patients' pathological states. The system is calibrated by adding monodispersed polystyrene spheres to the sample. [Work supported by the U.S. National Institutes of Health through Grant 2R01GM30419.]
The perceptual locus of spectral tilt
Authors: Richardson Kevin H. , Sawusch James R.
Published: October 2005

In a previous study [Richardson and Sawusch, J. Acoust. Soc. Am. Suppl. 1 85, S136 (1989)] using natural, synthetic, and modified voiced stops it was shown that spectral tilt does not play a role in human stop identification. In the present study, subjects were presented with three sets of tone analogs that mimicked the voiced stops [b], [d], and [g] in conjunction with the vowels [ɛ], [al, and [u]. All stimuli were based on the speech tokens described by Richardson and Sawusch (1989). The first set (“natural” tones) was based upon high-quality, synthetic CV tokens. The second set (“stylized” tones) was also based upon the synthetic CV tokens. In this set, each token with the same vowel (e.g., [ba], [da], and [ga]) was given the same set of parameter values as for the vowel portion of the syllable. The third set (“modified” tones) was based upon the stylized tones and contained identical changes in spectral tilt for each stop place of articulation. Both speech and nonspeech subjects were run in a perceptual grouping task in order to investigate the perceptual locus of any effects of the change in spectral tilt. Results will also be discussed in terms of general human auditory-phonetic coding ability and the nature of the phonetic representation used in speech perception. [Work supported by NIDCD Grant No. DC00219 to SUNY at Buffalo.]
Perceptual identification of ambiguous consonant onsets
Authors: Karnell Michael P. , Landahl Karen L.
Published: October 2005

Theories of acoustic invariance propose that stop consonant place identification can be made independently of full consonant-transition information. Consonant and vowel identification is possible within a few milliseconds of stop release, although the distribution of the acoustic energy in the consonant onset spectrum is frequently inconsistent with the distribution for the following vowel. The presence of oral physiologic impairment may be expected to influence whatever consonant-vowel interaction may contribute to syllable perception. The purpose of this study was to examine consonant/vowel identification for two glossectomee speakers and one normal control. For the most impaired speaker, removal of poorly identified vowel information enhanced consonant identification. For the normal speaker and the less impaired speaker, full CVs were well identified. Removal of vowel information diminished correct consonant identification for the glossectomee speaker but for the normal speaker affected only those consonants that had spectra consistent with the following vowel. The data show that when onset spectra are ambiguous, the vowel spectrum weights the onset spectrum to influence identification of the intended consonant place of articulation.
Are F2- and F3-onset frequencies equal cues for place of articulation
Authors: Li Xiao-Feng , Pastore Richard E. , Scheer Jennifer
Published: October 2005

This study reevaluated F2- and F3-onset frequencies as cues for place of articulation. Seven levels of F2-onset frequency, ranging from 600 to 1800 Hz, were factorially combined with eight levels of F3-onset frequency, ranging from 1400 to 4200 Hz, to create 56 synthetic syllables. Subjects were asked to classify each initial phoneme of the syllable into/ba/, /da/,/ga/, or/others/. A canonical correlation analysis was conducted to recover the relationship between the percentage of each response category and the values of F2- and F3-onset frequencies. The canonical correlation structure shows that F2-onset frequency has a high negative correlation with the /ba/ category, and a positive correlation with the/da/ category, while both F2- and F3-onset frequencies are moderately correlated with the /ga/ category. This result suggests that F2-onset frequency is an adequate cue to distinguish /ba/ from /da/. However, both F2- and F3-onset frequencies are interacted to cue /da/ and /ga/ distinction. This result is in contrast to claims that either F2- or F3-onset frequency is a strong cue for three place categories.
Age-related differences in formant-transition effects within syllables and across syllable boundaries
Authors: Nittrouer Susan
Published: October 2005

Previous work [S. Nittrouer and M. Studdert-Kennedy, J. Speech Hear. Res. 30, 319–329 (1987)] demonstrated that young children based phonemic judgments of syllable-initial fricatives on the formant transitions of the following vowel to a greater extent than did older children or adults. In this study, three sets of stimuli were developed to investigate further the effects of vocalic formant transitions on consonant judgments. Two sets consisted of monosyllables, and were used to measure transition effects on a preceding consonantal segment. One set consisted of disyllables, and was used to measure these effects on a following consonantal segment across a syllable boundary. All three sets were presented to adults and to children, 5 and 7 yr of age, who were asked to identify the stimuli. Results for the monosyllables showed that the effects of the vocalic formant transitions on consonant judgments declined with increasing age, while results for the disyllables showed that the effects increased with increasing age. These findings suggest that children at roughly 5 yr of age are most sensitive to whole-syllable forms, as represented here by within-syllable formant transitions. Then, as the segment gains independent status for the child, formant transitions come to be treated similarly within syllables and across syllable boundaries.
Asymmetries in vowel-fricative and fricative-vowel information
Authors: Whalen D. H.
Published: October 2005

Vocalic formant transitions have been shown to affect identification of both initial and final fricatives. However, Soli and Mann [J. Acoust. Soc. Am. Suppl. 1 73, S53 (1983)] found that transitions did not contribute as much to final as to initial fricative identification. The present study extends that work by manipulating the digitized waveform of spoken words (“sack,” and “shack,” “Cass,” and “cash”). Fricative continua were created by combining the natural /s/ and/ /∫ fricative noises in varying proportions. The vocalic segments, including initial or final transitions, were played forward or backward, so both types of transitions occurred in both positions. In each of these conditions, the individual pitch periods were either in their original direction or reversed (to control for the odd voice quality of reversed speech). Preliminary results with adult listeners show that both types of transitions are less influential with final fricatives than with initial fricatives. This seems to indicate that different perceptual strategies are used for different parts of the syllable. [Work supported by NIH Grant No. HD-01994.]
Compensation for talker variability and vowel variability in the perception of fricatives
Authors: Johnson Keith
Published: October 2005

In the perception of a fricative continuum from [s] to [∫], hearers are influenced both by rounding of a following vowel and by the gender of the talker. The experiment reported in this paper replicates and extends this finding. Subjects identified the initial fricative in CV syllables composed of synthetic fricatives from an [s]-[∫] continuum and natural productions of either [a] or [u]. A male and female talker produced the vowels. Vowel rounding produced a shift in the [s]-[∫] boundary both when syllables containing different vowels were randomly intermixed with each other and when the syllables were blocked by a vowel. However, the influence of talker gender was only present when the two talkers' productions were intermixed with each other. When syllables were blocked by the talker, no boundary shift occurred. Reaction time data had the same pattern for both sets of stimuli. Reaction time was longer when syllables with vowel or speaker differences were randomly intermixed. The boundary shift data suggest that the perceptual differences between talkers are enhanced when tokens are intermixed with each other, and generally that talker characteristics have a less robust effect on perceptual processing than do the properties of contextual segments. [Work supported by NIH Training Grant No. NS-07134-11 to Indiana University.]
The spectrogram as an aid in studying speech intelligibility at low S/N ratios
Authors: Plomp R. , van Beck J. H. M.
Published: October 2005

Current research [M. ter Keurs, R. Plomp, and J. M. Festen, Proc. Eur. Conf. Speech Commun. Technol. Paris 1, 251–253 (1989)] has shown that resynthesizing the speech signal from the output of a short-time fast Fourier transform (FFT) (16-ms time segments, with overlapping additions, phase relations preserved) results in speech almost indiscriminable from the input signal for spectral-envelope smearing over a bandwidth up to 1/8 oct. This means that the spectrotemporal energy distribution of a short sentence (2 s, 60–8000 Hz) is faithfully represented by a spectrogram consisting of about 7000 points. This representation can be of help to understand the effects of interfering noise, or a competing voice, by eliminating all points below a certain critical S/N ratio. Resynthesized speech signals without energy for the spectrotemporal elements corresponding to the eliminated points can be used to study the relative contribution of weaker components to speech perception. Examples will be given.
Simultaneous measurement of respiratory and laryngeal function during comfortable, soft, and loud speech
Authors: Stathopoulos Elaine , Sapienza Christihe M.
Published: October 2005

It is well known that both respiratory and laryngeal mechanisms are involved in changing vocal intensity [T. J. Hixon, JSHR 16, 78–115 (1973); N. Isshiki, JSHR 7, 17–29 (1964)], although these have generally been studied separately. The present investigation studied these functions simultaneously while adult speakers produced comfortable, soft, and loud speech. Respiratory function was measured using linearized magnetometers. Laryngeal function was assessed using an electroglottograph and circumferentially vented pneumotachograph. An intraoral air pressure tube was used for estimating subglottal pressure. Analysis of preliminary respiratory data showed the following trends: increased ribcage-, abdominal-, and lung-volume initiations, terminations, and excursions for loud as compared to soft and comfortable speech. Preliminary laryngeal function data indicate that open quotient decreased and estimated laryngeal resistance increased for loud as compared to comfortable and soft speech. Intraoral air pressure values doubled from comfortable to loud speech. Results indicate that respiratory and laryngeal systems are synchronized to produce changes in vocal intensity. Individual subject variability will be discussed in the presentation. [Work supported by NIH.]
Fundamental frequency variation in sustained vowel productions of 6- to 8-year-old children
Authors: Sapienza Christine , Sussman Joan E.
Published: October 2005

The purpose of this study was to determined the inherent variability of children's vocal fold vibration during sustained phonation of [a], [i], and [u]. Numerous studies (Koike, 1973; Horii, 1979) have provided normative values for the period-to-period variation in fundamental frequency (jitter or perturbation) in adults; however, little valid data are available for children's voices. The present investigation, unlike previous work, studied live voice productions, an approach that reduces signal distortion and measurement error. Thirty children, aged 6 through 8 years, and ten adult females participated in individual experimental sessions. Accelerometer measures (vibrometer model 501m601) of fundamental frequency (F0) and either F0 perturbation or jitter were calculated using both the Kay Elementrics Visipitch (model 6095) and cspeech software analysis program (Milenkovic, 1989). The following variables were studied: (1) vital capacity, height, weight, and gender compared to acoustic measures for children and (2) the amount of jitter (and F0 perturbation) for children versus adults. Additionally, Visipitch and CSpeech measures were correlated to observe their similarity. Results clarify whether developmental differences in the vocal fold structure of children are reflected in measures of F0 variability. Initial data will be provided for future comparison to measures from children with voice disorders.
VOT development in Hindi and in English
Authors: Davis Katharine
Published: October 2005

The present study compares voice onset time (VOT) productions across age groups in Hindi and in English, which have four-way and two-way phonemic voicing contrasts, respectively. Both voicing lead times and post-release VOTs were taken from initial velar stops in isolated monosyllabic words. Data were elicited from monolingual adults and children (ages 2–6 years). Vowel quality effects were controlled. A two-way analysis of variance showed that for all age groups in both languages, phonemic voice category had a significant effect on VOT. Pairwise comparisons on the Hindi data, however, revealed that, although all pair had significant mean post-release VOT differences in the adult group, significant /k/ vs /g/ differences were not noted until 6 years of age. The /k/ vs /kh/ pair did exhibit significantly different mean VOTs from the age of 2, suggesting that when wider mean VOT differences are noted in the adult phonemes, the children are more likely to acquire the contrast at an early age. The more complex /gh/ was not adultlike, even at 6 years. The English subjects demonstrated significant differences at all ages, perhaps because the English mean VOT differences are at least as wide as those in the Hindi /k/ vs /kh/ contrast. In both languages, lead timings were not adultlike in the younger groups, which supports the claim that lead voicing is more difficult to acquire than either short- or long-lag timing. Repeated measures analyses showed significant interactions for VOT between age group and the target phonemic category, demonstrating a steady progression toward the adult model. The implications of these results for a universal phonetic category system are discussed.
Acoustic and physiological study of traditional Japanese singing
Authors: Kobayashi Noriko , Tohkura Yoh'ichi , Tenpaku Seiichi , Ohyama Ghen , Honda Kiyoshi , Niimi Seiji
Published: October 2005

Acoustic and physiological characteristics of four genres of traditional Japanese singing were extracted. Subjects were professional singers of each genre: Sohkyoku, Yohkyoku, Minyoh, and Kyogen. Audio and video-fiberseopic recordings were made, while the singers were producing the singing voice of some typical phrases of their singing modes and the speaking voice as well. EGG recording was also made for a singer of Kyogen. Spectral analyses revealed prominent peaks at 4–4.5 kHz in the subject's singing voice, implying an evidence for the “singing formant” of traditional Japanese singing. Acoustic characteristics of the peculiar tone ornament suggest that the singers controlled F0 and intensity independently. Fiberscopic observation of the vocal tract and EGG signals provided some physiological bases to understand the singers' fine control of the phonatory system for such specific voice production.
Distinctive characters of the articulation of r-like sounds
Authors: Rongrong Liao
Published: October 2005

Linguists have been paying attention to r-like sounds for a long time, trying to find both acoustic and articulatory aspects of the distinctive features of these sounds. Ladefoged et al. [J. Phon. 11, 291–302 (1983)] explained the grouping of these sounds across languages by “family resemblance” in articulation. Lindau [Phonet. Linguist., 157–168 (1985)] gave the same explanation to the grouping from an acoustic point of view. This study focuses on analyzing the place of articulation of r-like sounds by studying x-ray data from English, Chinese, Tamil, Telugu, Hindi, Urdu, Polish, and Russian. It argues for the extreme importance of the existence of a sublingual cavity for the distinctive articulation of sounds.
Placement variability in intraoral pressure
Authors: Wilcox Kim A. , Seikel J. Anthony , Drumright David G.
Published: October 2005

A traditional understanding of the speech waveform of vowels assumes that the extraoral acoustic output is the product of the combination of a glottal source and the filter function of the oral tract. This approach, while functional, does not assess point differences of the acoustic signal within the oral tract. The present study compares the output waveform with differences in intraoral pressure at specific locations within the oral cavity. A probe microphone system was developed to measure the localized signal at 68 points within the oral cavity. The present data show that the third formant varies most widely, with diminishing differences as the probe moved anteriorally. Observed variations in F3 include (1) additional resonant lobes, (2) frequency shifts, and (3) complete formant ablation. While F1 and F2 are relatively stable, the strength of component resonant lobes is shown to vary as a function of measurement location. Results will be displayed relative to an oral-cavity map. [Work supported by Univ. of Kansas, General Research Fund, and USDE.]
The features ATR in Akan and emphasis in Arabic
Authors: Lee Sook-Hyang
Published: October 2005

Akan contrasts two sets of vowels, one in which the tongue root is advanced and the larynx lowered (+ATR), and another in which the tongue root is retracted (−ATR) [Lindau, J. Phon. 7, 177–186 (1979)]. Arabic contrasts two sets of consonants, one in which the pharynx is constricted (+emphasis) and another in which it is not (−emphasis). Card [Cornell Ph.D. dissertation (1983)] observes that [+ emphasis] spreads to vowels and consonants within the same word. Lindau suggests that the two phenomena can be combined as various settings along a single phonetic dimension of pharynx width, with [+ ATR] as maximally expanded and [+ emphasis] as maximally constricted, and that this dimension can be reduced to the binary phonological feature [± expanded], since no language contrasts more than two settings. This paper tests this hypothesis. Measurements of pharyngeal diameter were taken from x-ray tracings from productions by one Arabic speaker and three Akan speakers, and multivariate analysis of variance was performed. The results showed significant interaction between the more and less expanded feature values and the two languages, implying that emphasis in Arabic is controlled by a different mechanism from that used for [± ATR] in Akan.
A comparison of glossometric measurements of tongue position with magnetic resonance images of the vocal tract
Authors: McCutcheon Martin J. , Lee Sungbok , Lakshminarayanan A. V. , Fletcher Samuel G.
Published: October 2005

The use of an opto-electronic sensing device called a “glossometer” for measurement of tongue position during vowel production has been previously reported [Smith et al, Biomedical Engineering V: Recent Developments, edited by S. Saha (Pergamon, New York, 1986)]. However, while repeatability of this measurement has been well established, its accuracy has not been established due to the lack of an alternative, low-risk technique for comparison. Recently, magnetic resonance (MR) images have been used to obtain vocal tract measurements. [Lakshminarayanan et al., RSNA, Work in Progress—Physics 173(P), 411 (1989)]. In this study, the performance of both systems was evaluated and compared using three custom-made, tongue-palate spacers to hold the tongue steady at three different positions. Distances measured using the two systems were compared with direct measurements of the spacers. It was found that distances measured from the MR images were accurate to within 2 mm in the worst case, but the glossometer demonstrated some distance-dependent error, suggesting a more refined calibration scheme for the glossometer. The experimental procedure and the result will be presented.
Visual perception of anticipatory rounding gestures
Authors: Escudier Pierre , Benoît Christian , Lallouache Tahar
Published: October 2005

The mechanisms of anticipation for the rounding gesture have been repeatedly investigated in previous works (see, e.g., the controversy between Lubker and Gay concerning the extent of anticipation in Swedish versus American English, or the support found in the French language for Henke's “look ahead” model as exemplified by data from Benguerel's famous “sinistre structure”). Concerning the visual perception of such an anticipation, McGurk [in The Cognitive Representation of Speech, edited by T. Myers et al. (North-Holland, Amsterdam, 1981), p. 336] has briefly mentioned an experiment using reaction times in CV identification. He demonstrated that listeners do take visual information about anticipation into account, and identify CV syllables on the basis of lip movement information prior to their being perceived auditorily. In the present experiment, this same result is found for French, with a different experimental protocol, taking into account simultaneous acoustic and articulatory measurements. Here, /zV1zV2/ trajectories (V1, V2, = /i/ or /y/), were used and compared with auditory identification data obtained from gated signals with results of visual identification for front face video images taken every 20 ms along the V1 → V2 trajectory. The following results were found: (1) Lip area transitions clearly show the asymmetry of vowel-to-vowel gestures. The transition from /y/ to /i/ begins at the acoustic: onset of the consonant, while the transition from /i/ to /y/ can begin very early in the /i/; (2) this anticipation of the rounding gesture is clearly perceived visually by the subjects who are able to identify the /y/ vowel before the end of the /i/; and (3) visual detection of the rounding gesture thus comes prior to its auditory detection, which seems, in fact, disturbed by the acoustic mixture of the vocalic gesture (/i/ → /y/ or /y/ → /i/) and the consonantal gesture (/z/). Implications for the timing and perception of the vowel-to-vowel gesture are discussed.
A fiber-optic interferometric flex disk accelerometer
Authors: Brown D. A. , Olcott J. E. , Garrett S. L.
Published: October 2005

A push-pull fiber-optic accelerometer, using an all-fiber Michelson interferometer will be described. The accelerometer consists of two “clamped” disks (4.6 cm in diameter, 1.0 mm thick, aluminum 6061-T6) that are joined at the outer boundary to a rigid cylinder and at the disk center by a rigid “spindle” that acts as a seismic mass. Flat spiral-wound coils attached to the inner surface of each disk detect the acceleration-induced strain in a manner similar to flexural disk hydrophone designs [Brown et al., Fiber & Int. Opt. 8(3), 169–191 (1989)]. The sensitivity below the disk's fundamental resonance of 2.8 kHz is 49 rad/g. The fractional phase change per unit force (1/φ) (δφ/δF) below the resonance is 56 × 10−12/N. A noteworthy feature of this sensor is that the sensing coils comprising the legs of the interferometer and the fiber coupler are totally internal to the sensor structure and thus are not exposed, making the sensor robust for industrial or shipboard applications. [Work supported by the Naval Postgraduate School Direct Funded Research Program and the Naval Sea Systems Command.]
A laboratory acoustic study of piezoelectric polymer hydrophones
Authors: Schrodt Joseph K.
Published: October 2005

This laboratory study was an evaluation of the acoustical and electrical properties of piezoelectric polymer (PVDF and PVF2/PVF3) materials. The task objective was to establish a technical framework for the future use of these materials in hydrophones. The technical approach was to investigate the polymer behavior in two configurations: (1) thick (500, 1000, and 1500 μm) copolymer (PFV2/PVF3) films bonded to various window and backing materials and (2) hollow cylinders with thin (28 μm) polymer (PVDF) film bonded to the inside wall of a selected window material. This study yielded copolymer hydrophones with a flat frequency response from less than 100 Hz to greater than 100 kHz and with receive sensitivities similar to those of standard ceramic (PZT) hydrophones (greater than − 200 dB re: 1 V/μPa). The conformable and lightweight nature of the polymer materials facilitated their use in the hydrophone fabrication. The broadband response and physical nature of the polymer films were in direct contrast with the highly resonant behavior and rigid nature of PZT ceramics.
A method for the direct audio frequency high-temperature (up to 1200 K) measurement of acoustic absorption
Authors: George Wallace R. A.
Published: October 2005

A special capacitive annular plate-diaphragm high-temperature acoustic (HTA) transducer was designed by the author to be operable to temperatures of up to 1000 K. This transducer is placed at one end of a long heated tube; the other end is reflectively terminated. An acoustic pulse signal is introduced at right angles to the center of the tube. The acoustic transmitter used can be thermally decoupled from the heated tube by using a cooling section. The acoustic pulse entering the tube splits up into two equal parts. The first part goes directly to the HTA transducer; the second part at first travels toward the reflective termination, then returns toward the HTA transducer. The acoustic absorption coefficient is obtained from taking a transfer function between the initial pulse and the second pulse received by the HTA transducer. Some of the first acoustic measurements in gases at temperatures up to 1200 K are reported. Time (ensemble) averaging was used to improve S/N ratio.
A method for determining the mechanical impedance of transducers
Authors: Ge Li-Feng
Published: October 2005

A linear electromechanical system consisting of an electrodynamic-type or piezoelectric-type vibration exciter with a transducer load can be described as a linear fractional (Möbius) transformation, i.e., W = (AZ + B)/(CZ + D), where A, B, C, and D are four-pole parameters of the exciter, Z is the mechanical impedance of the load, W is the electrical input impedance of the exciter, and all quantities are complex. Three pairs of datapoints (Wi and Zi, i = 1,2,3 ) uniquely determine the transformation. The reciprocity theorem, AD − BD = ± 1 (the plus sign for piezoelectric type, the minus for electrodynamic type), stipulates the inherent relationship between the four parameters. The mechanical impedance of the transducer is just its inverse function, Z = (DW − B)/(− CW + A). Experiments were performed on piezoelectric-type exciters that compared the impedance of accelerometers with a set of mechanical standards. The results show that at frequencies below 3 kHz, the impedance of an accelerometer is the same as that of a standard that has the same static mass, like a rigid body. At high-frequency range, 3–20 kHz, even up to ultra-high-frequency range, above 20 kHz, the impedance of the accelerometer is consistent with that of the standard as a one-dimensional elastic body, except for the resonant case. Since the system with the transducer has a lower resonant frequency than with the standard, the transducer load has a larger impedance magnitude than the standard load in the resonant band. [Work supported by the NIST.]
Application of wave propagation models and simulated annealing to seismo-acoustic inverse simulations
Authors: Collins Michael D. , Kuperman W. A. , Schmidt Henrik
Published: October 2005

Frequency-domain seismo-acoustic inverse models attempt to determine the ocean bottom parameters to the appropriate depth and resolution for the frequency involved. For realistic problems, the number of parameters to be estimated can be very large. For inverse models based on wave propagation models, the estimate for the bottom parameters corresponds to the parameter values for which the synthetic wave solution best agrees with the measured data. Since solving the frequency-domain wave equation in underwater environments can require significant computation time, it is usually not practical to perform an exhaustive search for the best solution. Simulated annealing is an efficient method for solving large optimization problems. The application of this method to seismo-acoustic inverse simulations will be discussed. In stratified environments, this approach is practical for determining the depth dependence of the parameters as well as the locations of interfaces. Simulated annealing is analogous to the formation of a perfect crystal by slowly cooling a pure liquid substance. To develop an efficient simulated annealing algorithm for the inverse problem, the appropriate analogy appears to be that of a mixture of liquids with different freezing points, where both the depth within the bottom and the parameter type determine the molecular species.
Surface wave, wave group, and internal wave observations in the 1988 Monterey Bay Tomography Experiment
Authors: Lynch James F. , Newhall Arthur E. , Miller James H. , Chiu Ching-Sang , Dees Robert C. , Schaaff Kevin P. , Paulsen Sönke
Published: October 2005

In December 1988, an experiment was conducted in Monterey Bay, California in order to verify earlier work [Miller et al., J. Acoust. Soc. Am. 86, 326–345 (1989)] that proposed using acoustic tomography to observe the surface wave frequency-direction spectrum. This experiment also looked at the effects of internal waves upon the acoustic arrivals in a complicated coastal environment. In this presentation, the main concentrate will be on the acoustic determination of the surface wave spectrum. The basic issues addressed are the identification, stability, and resolution of the multipath arrivals. The directional resolution of the surface wave spectrum is examined. Detailed comparisons of the spectra generated by inversions of the acoustic field to “ground-truth” measurements made by a nearby NDBC wave buoy are shown. The acoustic data also show the appearance of a strong spectral peak due to wave groups that is not observable by the NDBC buoy. At lower frequencies, spectral peaks are observed that are attributed to internal wave activity. An interesting possibility for the generation of the observed internal wave peaks is the nonlinear interaction of two noncolinear surface waves. This mechanism, as well as other possible mechanisms for the generation of the internal wave spectral peaks, will be discussed. [Work supported by ONR and the Naval Postgraduate School Research Council.]
Monitoring El Niño by using modal ocean acoustic tomography
Authors: Shang E. C. , Wang Y. Y.
Published: October 2005

The El Niño-Southern Oscillation (ENSO) phenomenon has been identified as the most powerful family of atmospheric and oceanic variations on a time scale of months to several years. To detect the El Niño onset and estimate its intensity as early as possible are a challenge for global climate forecasting and modeling. In this paper, the possibility of monitoring El Niño by using modal ocean acoustic tomography (MOAT) [Shang, J. Acoust. Soc. Am. 85, 1531́1537 (1989)] has been investigated. A simple acoustic model of El Niño based on the 1982–1983 event (Georges et al., 1988) has been used for numerical simulation. It has been found that acoustic modes 7–12 at 10 Hz can properly sample the effective El Niño profile (from the surface to a 250-m depth). Both forward (modal travel time and kernel matrix synthesis) and backward (El Niño profile inversion) processes are carried out on a CYBER 205. The retrieved El Niño profile is very promising. [Work supported by NOAA and ONR.]
Hearing sensations and noise quality evaluation
Authors: Fastl Hugo
Published: October 2005

Noise quality can be assessed subjectively along different perceptual dimensions, called “hearing sensations.” Of particular relevance for noise quality evaluation are the hearing sensations loudness, sharpness, and fluctuation strength. The dependence of these hearing sensations on important stimulus parameters is briefly reviewed. In addition, the physical evaluation of noise quality by means of a loudness meter in accordance with ISO 532B is demonstrated. Subjective and physical noise evaluations are compared. [Work supported by DFG.]
The influence of nonacoustic factors on judgments of the annoyance of noise exposure
Authors: Fidell Sanford , Green David M.
Published: October 2005

A theoretical model recently developed under sponsorship of the U.S. Air Force Noise and Sonic Boom Impact Technology Program treats annoyance judgments as the outcome of rational decision-making processes. Self-reports of the annoyance of noise exposure are partitioned into two components: one attributable to acoustic factors and one attributable to nonacoustic factors. This approach makes it possible to quantitatively estimate the contributions of nonacoustic factors (referred to collectively as “response bias” to judgments of the annoyance of noise intrusions. Application of this model to predicting the prevalence of annoyance due to different community noise sources is described.
Vibration response of and propagation in fluid-loaded finite plates
Authors: Smith Donald E. , Burroughs Courtney B.
Published: October 2005

An analytic model of the vibration response of long finite fluid-loaded plates simply supported along the short edges, and either free or simply supported along the long edges, is developed. The drive-point and transfer admittances of the free and simply supported plates are presented as a function of frequency wavenumber, and the frequencies and wavenumbers of the resonant responses of the plates are identified. The propagation from single point drives (which excite all wavenumbers) at one end of the plate to the frequency/wavenumber response at the other end of the plate is investigated. Also, the vibration propagation from arrays of point drives, steered to specified wavenumbers, and pure wavenumber drives at one end to the frequency/wavenumber response at the other end of the free and simply supported plates is explored.
Models of speech and hearing and their applications: Overview and outlook
Authors: Schroeder Manfred R.
Published: October 2005

Electronic speech coding had its origin in 1928 when Homer Dudley proposed to send speech signals over a new transatlantic telegraph cable with the (then) enormous bandwidth of 100 Hz. Dudley argued that speech was generated by slowly moving articulators and should therefore require only some 100-Hz total bandwidth for transmission. Since extraction of these parameters proved difficult, Dudley suggested, as an alternative, the transmission of the likewise slowly changing spectral information. The result was the channel vocoder, which (together with formant and voice-excited vocoders) dominated speech coding and that of musical sounds of single-pitch instruments until the mid 1960s. Unhappy with the vocoder's “electronic accent.” Bishnu Atal and the author, in 1967, advanced the idea of linear predictive coding (LPC), motivated by the desire to replace rigid vocoderlike coding by a more flexible method in which a “prediction residual” could represent deviations of real speech signals from an assumed all-pole model. In 1972, subjective error criteria were introduced, based on auditory models of masking and the possibility of “hiding” quantizing noise under the speech signal. The resulting code-excited linear predictive (CELP) coders based on statistical models have been operated at 1/4 bit per sample for the residual at virtually no audible degradation. With powerful digital signal processing chips, CELP has now become the method of choice for synthetic-voice applications. For musical sounds, masking models and linear predictive coding, which is equivalent to prewhitening of the spectrum, lead to a substantial reduction in the required number of bits per sample.
Sonoluminescence from single bubbles
Authors: Gaitan D. Felipe , Crum Lawrence A.
Published: October 2005

Sonoluminescence (SL) is generally attributed to the radiative recombination of hydroxyl radicals produced by the high temperatures and pressures associated with cavitation bubble collapse. SL from a single bubble has been observed in a levitation cell at 20 kHz, which supports this assumption. The pressure amplitudes ranged from 110 kPa for water to 170 kPa for 60% glycerin in water. Pulsation amplitudes were measured to be between five and ten times the equilibium radius. Such large amplitude steady-state pulsations have never been observed before. The possible mechanisms by which stability is maintained will be discussed and theoretical calculations of temperatures and pressures inside the bubble will be presented. [Work supported by ONR.]
Field potentials in rat brain stem during binaural acoustic stimulation
Authors: Gaumond Roger P.
Published: October 2005

Electric field potentials were measured in rat brain stem while presenting monaural or binaural acoustic click stimuli. The binaural difference (BD) potential, defined as the sum of field potentials due to menaural stimuli minus that due to a binaural stimulus, was recorded at 1-mm intervals along a track passing through the inferior colliculus and the superior olivary nuclei. Scalp surface potentials were recorded simultaneously. Prominent BD potentials were observed at all intracranial locations. Scalp surface BD was contemporaneous with an intracranial BD waveform that reversed sign at a level midway between the inferior colliculus and the olivary nuclei. The onset of BD potentials at or below this level occurs 1 ms after the appearance of prominent monaural and binaural response waveforms. This latency difference suggests the existence of an additional synapse in the pathway leading to the structure responsible for BD generation compared to pathways leading to other structures in the superior olivary complex. [Work supported by Penn Lions Hearing Research Foundation.]
Observation of slow compressional waves in natural rocks
Authors: Nagy Peter B. , Adler Laszlo
Published: October 2005

Slow compressional waves in fluid-saturated porous solids offer a unique acoustical means to study certain material properties, such as tortuosity and permeability. Unfortunately, geophysical application of this promising technique turned out to be unfeasible since clear indications of slow wave propagation have never been observed in natural rocks. A novel technique based on the transmission of airborne ultrasound through air-filled porous samples is presented. The suggested method can be used to measure the velocity and attenuation of the slow compressional wave in a wide frequency range. More importantly, the technique is so sensitive that it provided the first irrefutable evidence of slow wave propagation in fluid-saturated natural rocks. Experimental results on slow wave velocity and attenuation in different artificial and natural materials are presented and shown to be in good agreement with theoretical predictions.
Interpenetrating network polymers as underwater damping materials
Authors: Ting Robert Y.
Published: October 2005

In recent years, new blends of crosslinking polymers have been developed to form interpenetrating network (IPN) structures that contain no covalent bonds or grafts between the networks. These IPNs can be prepared so that component polymers with good miscibility would lead to domains as small as 0.1 &μm or less. Such a finely dispersed two-phase morphology suggests that the IPNs are potentially useful for underwater damping applications. In addition to the damping characteristics of component polymers, one could also take advantage of the internal friction between the two networks as a new loss mechanism in the material. A series of IPN samples containing urethane-epoxy networks have been designed in order to demonstrate their potential as a new class of damping materials. The samples were prepared via a simultaneous polymerization technique, and their dynamic mechanical properties were determined to show a broadband damping behavior. The effects of urethane/epoxy ratio, fillers, cure conditions, and water soaking on these properties were also studied.
Comparison of a rigid and a dynamic structure absorber model
Authors: Hoffman Thomas L. , Marty Beat
Published: October 2005

Rayleigh's model for porous material is based on a rigid frame consisting of parallel tubes. In order to extend the model to consider the structure-borne sound transmitted through the skeleton of an absorbent, a model derived by Zwikker and Kosten was used. This model introduces a dynamic structure matrix while leaving the basic concept of Rayleigh's model untouched. The theoretical results show that in the case of heavy absorbers (density > 100 kg/m3) or thick absorbers (thickness > 0.5 m) the structure takes over the main contribution of the transmission. Resonance phenomena are obtained for the case of absorbers of finite thickness. The use of absorbing material in double partition walls in theory and practice shows only a minor influence of the transmission loss caused by structure borne sound. Only if very heavy or thick layers of absorbents are used the structure-borne sound transmitted through the frame may exceed the sound conducted by the enclosed air. For all other cases Rayleigh's model is sufficient to determine the transmission loss.
Auditory models for speech coding
Authors: Ghitza Oded
Published: October 2005

Traditional speech coding schemes are designed to produce synthesized speech with a waveform (or a spectrum) that is as close as possible to the original. With limits on the bit rate, however, it would be better to produce synthesized speech that matches the original speech at the auditory-nerve level. Current models of the auditory periphery enable us to simulate auditory-nerve firing patterns in a fairly accurate way. Simulated neural firings produced by speech signals show properties that are different from properties of other spectral representations. In particular, the short-term interspike-interval statistics over the entire simulated auditory nerve were studied. First, the perceptual relevance of this representation was validated. This was done by showing that subjective opinion scores of high-quality (above 8 kbits/s) synthesized speech can be predicted by using an L1 distance metric between the interspike-interval histograms produced by the original and the coded speech signals. Then, by using this measure inside the analysis-by-synthesis loop of a code-excited linear predictive (CELP) speech coder, limitations in the current structure of the coder were found that confine its performance.
Response of the shear layers separating from a circular cylinder to small amplitude rotational oscillations
Authors: Filler Jeff R. , Marston Philip L.
Published: October 2005

The responses of the shear layers separating from a circular cylinder in water to small amplitude rotational oscillations of the cylinder were investigated experimentally in the Reynolds number (Re) range 250 to 1200 [J. R. Filler, Ph.D. dissertation, Washington State University (1989)]. Magnitude and phase of the response (in terms of velocity fluctuations in the shear layers) were measured using a hot film anemometer connected to a phase-sensitive detector. The hot film was placed in the shear layer approximately one diameter downstream from the cylinder. Synchronous velocity oscillations were found to be roughly linear in the driven rotational amplitude. At lower Re, cylinder oscillations are shown to excite the common Strouhal (or Karman) mode of vortex shedding. Near the Strouhal frequency there is a rapid 180° phase jump characteristic of a driven oscillator. Above Re≈500, a secondary mode of vortex shedding or instability is also excited associated with the instability of the free shear layers. Frequencies of maximum response in this range agree with frequencies of maximum amplification predicted analytically by others for free shear layers. The response phase varied with frequency as expected for waves convected on a shear layer. [Work supported by ONR.]
Nonlinear analysis of transitional and turbulent boundary layer noise
Authors: Katz Richard A.
Published: October 2005

The boundary layer over an axisymmetric surface is characterized by three types of flow; laminar, transitional, and turbulent. The latter stages of the laminar boundary layer are characterized by infinitesimal linear wavelike disturbances, the so-called Tollmien-Schlichting (TS) waves that amplify spatially in the downstream direction. The nonlinear nature of transition produces spectra containing not only the TS frequencies, but sum and difference frequencies as well. Moreover, by applying nonlinear techniques (chaos theory) to evaluate the fluid dynamics within the boundary layer, there is some experimental evidence of the persistence of an underlying structure from transitional to full boundary layer turbulence, that may be associated with the TS mode. The analysis of both theoretical and experimental work in a boundary layer flow leading to these results is the subject of this paper.
Performance and sensitivity of matched-field and uncertain-field processor approaches
Authors: Richardson Anthony M. , Nolte Loren W.
Published: October 2005

Matched-field localization methods often show a high sensitivity to acoustic variabilities due to the mismatch between the assumed and actual acoustic environments [A. Tolstoy, J. Acoust. Soc. Am. 85, 2394–2404 (1989)]. In this paper an uncertain-field processor is developed based on signal detection and estimation theory. It takes into account, a priori, the uncertainty in the sound-speed profile and hence is less sensitive to mismatch. The Munk profile, c(z) = c0(1 + ε{exp[(z − z0)/β] + (z − z0)/β − 1}), with uncertainty in the axis depth, z0, and the sound speed at the axis depth, co, is used to model acoustic variabilities. Localization performance and sensitivity are presented to illustrate the advantages of taking into account, a priori, the uncertainties in the sound-speed profile for a long-range deep-ocean environment. [Work supported by ONR and North Carolina Supercomputing Facility.]