bluuebunny/crossref_metadata_2025 huggingface dataset:
Delayed matching-to-sample by an echo-locating bottlenose dolphin
Authors: Roitblat H. L. , Penner Ralph H. , Nachtigall Paul E.
Published: October 2005

An Atlantic bottlenose dolphin (Tursiops truncatus) was trained to perform three-alternative delayed matching-to-sample while wearing eye cups to occlude its vision. Samples and comparison stimuli consisted of small aspect-independent three-dimensional stimuli. Observing responses, in the form of echo-location clicks, were recorded during the presentation of the sample as well as during the presentation of the comparison stimuli. The location, duration, and rate of clicks to the sample and to each comparison stimulus was recorded. Over 48 sessions of testing, choice accuracy averaged 94.4% correct. Stimuli varied in the number of clicks necessary to identify it as the sample. Examination of the number of echolocating signals emitted and their distribution over locations reveals a complex decision making process in which stereotyped sequences are combined with contingent item identification to yield accurate performance. A model for the dolphin's decision-making processes is described.
Learned perceptual categories for complex vocal signals in budgerigars (Melopsittacus undulatus)
Authors: Doeling Robert J. , Brown Susan D. , Park Thomas J. , Okanoya Kazuo
Published: October 2005

Operant conditioning and multidimensional scaling (MDS) procedures were used to study auditory perception of complex vocal signals in budgerigars. Response latencies were anlyzed by MDS to produce a spatial arrangement of these complex sounds reflecting the perceptual organization. Both normal and isolate-reared budgerigars and humans show perceptual categories which correspond closely to the major functional and acoustic categories of species-specific calls. Birds sharing the same learned call show perceptual categories for the calls of individual birds. Humans and other budgerigars unfamiliar with these same learned calls fail to group calls by individual. These results suggest that both general and special auditory mechanisms are involved in the formation of perceptual categories for species-specific vocal signals in budgerigars. Additional tests with human speech sounds suggest that the general auditory processing mechanism in budgerigars are quite sophisticated. [Work supported by NIH.]
Echo suppression or localization masking?
Authors: Divenyi Pierre L.
Published: October 2005

A brief dichotic conditioner (C) has been shown to effectively disrupt lateralization of a brief probe (P) presented after a short interval (4–7 ms, onset to onset) with an interaural time delay that is perfectly audible in the absence of the C [P. M. Zurek, J. Acoust. Soc. Am. 66, 1750–1757 (1980)], even when the C and the P are different sounds [P. L. Divenyi and J. Blauert, in Auditory Processing of Complex Sounds, edited by W. A. Yost and C. S. Watson (Erlbaum, Hillsdale, NJ, 1987), pp. 146–155]. An echo suppression mechanism responsible for this effect would predict (1) suppression to be strongest when the C and the P are identical and to decrease monotonically as the spectra of the two sounds are made different, and (2) a monotonic falloff of suppression when the temporal separation between the two sounds is increased beyond a certain minimum. In the present experiments, the effects of frequency separation and temporal separation between a narrow-band P centered at 2 kHz and a C were systematically explored. Contrary to the predictions, low-frequency (0.8 < 1.3 kHz) C's were more effective in suppressing the lateralization of the P than those closer to the P frequency, and lateralization performance was nonmonotonically related to temporal separation between C and P. The results suggest that a dichotic stimulus with a relatively high localization strength could “mask” the localization of another, subsequent dichotic stimulus. [Work supported by the Veterans Administration.]
A control mechanism of voice intensity in relation to expiratory and laryngeal functions
Authors: McCafferty Reiko M. , Kakita Yuki , Nakata Morihiko
Published: October 2005

A model explanation of controlling voice intensity in relation to expiratory and laryngeal functions is reported. Using the phonatory function analyzer PS-77 (Nagashima Medical Instruments, Tokyo), a log-linear relationship between the vocal intensity I* (dB) and the mean airflow rate U(cm3/s) was obtained during a stepwise increment of intensity with a constant pitch. More precisely, a piecewise linear relationship with an S-shaped pattern was obtained in an I* vs U* display, where U*equals; 20 log (U/U0). At most, three line segments with different slopes are necessary to approximate these relationships. To examine, theoretically, the controlling mechanism of the intensity for the different slope values in I* vs U* display, a simple intermittent triangular wave was assumed as the glottal sound. Using the model waveform, the vocal intensity can be expressed by a functional relationship with the mean airflow rate U and the open quotient. Based on this functional relationship and speculation on the physiology voice production, the contribution of laryngeal control and expiratory control on vocal intensity is discussed. Results of the experiment indicate that laryngeal control is more dominant in the middle intensity region than in either of the higher or the lower intensity regions. These findings may contribute to developing an effective means of noninvasive voice assessment.
Cross-language effects of vowels on consonant onsets
Authors: Keating P. A. , Cohn A. C.
Published: October 2005

Languages appear to differ in how much consonants coarticulate with vowels. Previously reported was an attempt to develop a metric of vowel effects on consonants so that quantitative comparisons of languages can be made. For each place of articulation in a given language, onset spectra are made of stop consonants before an /a/ vowel. Templates for each place of articulation are used to characterize these spectra. Then the templates for a language are tested against the other vowel contexts within that language. The extent to which the templates fail to generalize across vowels within each place of articulation is argued to reflect the degree of coarticulation in the language. An earlier study of Kana and Russian has been expanded to include English and Polish, so that four languages can be compared. As expected, the measure of template generalization (degree of coarticulation} varies across languages, though languages also differ in the behavior of individual consonants and vowels. Possible phonological motivations for such variation will be discussed. On the basis of the four languages analyzed, the advantages and limitations of using templates to construct a coarticulation metric will also be discussed. [Work supported by NSF.]
How coarse is glottal/oral coordination?
Authors: Kingston John
Published: October 2005

Chasaide and Gobl [J. Acoust. Soc. Am. Suppl. 1 82, S116 (1987)] show that the glottal opening in a voiceless stop is anticipated in a preceding vowel for some speakers of Swedish and English. This opening is only partial and the glottis is not fully abducted until the stop closure is made. Chasaide and Gobl argue that this early glottal opening and the implied coarse coordination with the oral gestures are a typical feature of the [voice] contrast in languages where the contrast is realized as unaspirated versus aspirated (they also showed that in French, where the [voice] contrast is realized as voiced versus voiceless, glottal abduction is not anticipated in the vowel preceding a voiceless stop). Data from two speakers of Icelandic [J. Kingston, J. Acoust. Soc. Am. Suppl. 1 82, S114 (1987)] revealed a contrast between abduction that begins in the preceding vowel, and abduction whose onset is synchronized with the oral closure in that language. Early abduction is found in Icelandic's preaspirates and abduction is synchronized with closure in other stop types [M. Petursson, Phonetica 33, 169–198 (1976)]. Two accounts are possible: (1) following Chasaide and Gobl, the extent of overlap between glottal abduction and the preceding vowel could simply be proportional to the size of the abduction—larger abduction in the preaspirates producing more overlap with the preceding vowel; or (2) Icelandic speakers may control when abduction begins independent of how large a glottal opening is made. That the language bases a contrast on whether glottal abduction overlaps with the preceding vowel, together with other acoustic evidence favors the second alternative. [Work supported by the Arts College, Cornell University.]
Wave-vector-frequency spectral estimation: A review of conventional signal processing techniques
Authors: Strawderman Wayne A.
Published: October 2005

Signal processing techniques for estimating wave-vector-frequency spectra of space-time fields from measured data parallel those developed by electrical engineers for estimating frequency spectra from measured samples of temporal fields. This paper reviews a conventional technique for estimating the wave-vector-frequency spectrum from samples of a space-time field measured through an array of sensors. The mean value of this specral estimate can be related to the true spectrum of the space-time field and the wave-vector and frequency responses associated with the various components of the signal processing. This relationship permits, under certain conditions, the quality of the spectral estimate to be assessed. The dependence of the quality of the spectral estimate on the various components of the signal processing is discussed.
The application of multichannel measurement techniques instructural acoustics
Authors: Felt D.
Published: October 2005

Measurements made on distributed arrays of sensors can be used to extract useful characteristics of the structural acoustic fields and the sources generating them. In this presentation, two experiments performed on elastic cylindrical shells immersed in water are discussed. In one case, the shell could be considered to be unstiffened, while, in the other, the shell had discrete ring stiffeners. Measurements were performed with both line arrays of accelerometers as well as hydrophones. Wavenumber frequency plots are obtained in all cases. This type of analysis on the accelerometer data shows clear evidence of both quasiflexural as well as quasilongitudinal waves in the shell response. The hydrophone data indicate the presence of two strong acoustic components, one traveling at grazing incidence to the array, while the other passes over the hydrophone array with a trace wave speed coincident with a wave generated on the shell traveling with the speed characteristic of a quasilongitudinal wave. For the measurements performed with the rib-stiffened shell, the wavenumber frequency plots show the presence of the ribs as aliased versions of the dispersion curves for the unribbed case. The theoretical basis for this is derived.
Modifying sound speed to reduce phase errors in parabolic equations by a Toda flow method
Authors: Driessel Kenneth R. , Wood David H.
Published: October 2005

It is well known that the standard parabolic wave equation, in the absence of range dependence, has the correct normal nodes (amplitudes) but incorrect eigenvalues (phase). This is regrettable because the desired information is generally more sensitive to phase errors than to amplitude errors. Several authors have attempted to increase the accuracy of the phases by modifying the sound-speed profile, even though this decreases the accuracy of the amplitudes. Attempts have been made to eliminate the phase errors (accepting the increase in amplitude errors) by a Toda flow method. From a given sound-speed profile, one can easily generate a matrix with the desired eigenvalues. The spectral mapping theorem shows that a certain square root of this matrix would have eigenvalues that are distorted in the opposite way from the parabolic wave equation. The modified sound-speed profile that corresponds to the last matrix is sought: A system of spectrum-preserving differential equations is solved giving the evolution of this matrix into one where the modified sound-speed profile can be recovered.
A parametric array for use as an ultrasonic proximity sensor in air
Authors: Lee Yang-Sub , Hamilton Mark F.
Published: October 2005

An ideal ultrasonic proximity sensor has long range, high resolution, and small size. However, the absorption of sound by air makes all three characteristics difficult to achieve simultaneously with conventional acoustical designs. In this paper, the nonlinear parabolic wave equation is used to investigate the possibility of utilizing a parametric array to incorporate all three desirable characteristics. To avoid difference frequency generation at the source, one of the primary beams may be radiated from a circular (disk) source, the other from a ring source that is concentric with the disk. First, the two primary wave fields are compared, with special attention devoted to radiation from a ring source. Second, the difference frequency field is analyzed as a function of source conditions. It is concluded that, for a source with a nominal radius of 1 cm, operating in air with primary frequencies of approximately 200 kHz and on-source sound-pressure levels up to 140 dB (re: 20 μPa), the parametric array offers no distinct advantage over conventional ultrasonic proximity sensors. [Work supported by NSF, ONR, and the Cray Research Foundation.]
A nonlinear, parametrically driven, variable-reluctance electroacoustic transducer
Authors: Wright W. B. , Swift G. W.
Published: October 2005

There is a well-known class of nonlinear acoustic drivers in which an acoustic force (or pressure) is exerted by the magnetic interaction of an electric current with itself, so that the force is proportional to the square of the current. The St. Clair driver [H. W. St. Clair, Rev. Sci. Instrum. 12, 250 (1941)] is the best-known device of this class. Less well known is the inverse effect, the nonlinear generation of an electric current by an acoustic vibration, achieved in the same apparatus. In the present case, a resonant series LC circuit is excited by varying L (geometrically, by acoustic vibration) at twice the resonance frequency of the LC circuit. The resonance requirement and inherent overwhelming nonlinearities make this system useless as a high-fidelity microphone. But several interesting non-linear dynamical phenomena can be observed with this simple system; and, in addition, it is capable of highly efficient power transduction. [Work supported by DOE/BES.]
Long-range, range-dependent, acoustic propagation simulation using a full-wave, finite-element model coupled with a one-way parabolic equation model
Authors: Chin-Bing Stanley A. , Murphy Joseph E.
Published: October 2005

A full-wave, range-dependent, ocean acoustic propagation and scattering model based on the finite-element (FE) method [J. E. Murphy and S. A. Chin-Bing, Math. Comput. Modeling 11, 70–74 (1988)] has been combined with a range-dependent, one-way parabolic equation (PE) model to simulate long-range (> 100 km) ocean acoustic propagation. This hybrid FE/PE model has the advantage that it includes the coupled effects of the full-wave, range-dependent, forward propagated and backscattered fields where full-wave effects are important, while allowing for the much faster computational marching method of the PE model in those ocean regions where full-wave effects are not significant. The FE/PE hybrid model also uses the FE full-wave, range-dependent solution from the source out to a specified range at which the pressure field serves as the initial field input to the PE model. This PE starting field is most useful when the source is near a severely range-dependent boundary. Numerical examples are given and comparisons made with the more “exact” coupled mode and finite-element models that illustrate the increased accuracy of this hybrid FE/PE model over the one-way propagation models. [Work supported by ONR and NORDA.]
New techniques for investigating the properties of chaotic ray paths
Authors: Palmer D. R. , Georges T. M. , Jones R. M.
Published: October 2005

It has been established that acoustic ray paths in a range-dependent ocean environment can exhibit chaotic behavior [Palmer et al., Geophys. Res. Lett. 15, 569–572 (1988)]. The usual techniques for identifying chaotic rays are the examination of Poincaré sections and power spectra of path depth, as well as the observation of exponential sensitivity to initial conditions. These techniques are not always useful, however, and are not directly related to observable signal characteristics. Travel times, ray elevation angle at axis crossings, and upper and lower turning point depths have practical relevance and provide new insights into the character of chaotic rays. Since this effort involved the numerical calculation of ray paths for both the Helmholtz and parabolic equations, procedures were developed for comparing results obtained for the two equations.
A survey of acoustic techniques for monitoring El Niño
Authors: Georges T. M. , Palmer D. R. , Jones R. M. , Riley J. P.
Published: October 2005

The challenge of understanding the El Niño-Southern Oscillation (ENSO) cycle in the equatorial Pacific Ocean is a test of one's abilities to observe, model, and forecast the processes of global climate change. Monitoring the structure, dynamics, and energetics of the ocean interior on the space-time scales of the ENSO signal appears to be a task for acoustic remote sensing. Therefore, the following acoustic strategies for monitoring ENSO-induced changes in the upper ocean are examined: (1) ocean acoustic tomography, (2) a long-range acoustic thermometer, (3) passive monitoring of ambient acoustic noise level, (4) an occultation technique that depends on bottom absorption, and (5) space-time scintillation analysis. Models of the ocean's acoustic properties are formulated from measurements made during the 1982–1983 ENSO event and simulated acoustic amplitude and travel-time measurements to find out how sensitive they are to the temperature changes that accompany a strong El Niño.
A technique for obtaining acoustic levels from geophone data
Authors: Fisher C. A.
Published: October 2005

The hydrophone, which measures pressure, is the instrument most often used for measuring acoustic phenomena in underwater environments. A geophone, which measures particle motion, can also be used to evaluate acoustic phenomena in the ocean. In the ideal case of an acoustic plane wave, the particle motion sensed by the geophone can be converted to the equivalent pressure with an impedance correction factor. This simple approach is not appropriate in situations where the acoustic wave is nonplanar. This paper compares pressure and particle motion predicted by the SAFARI pulse model to obtain a transfer function for converting particle motion to pressure. For various scenarios, this transfer function is compared with the commonly used impedance correction factor.
Acoustical design of Tokyo Geijutsu Bunka-Kaikan. Part 1. Study of room allocation for subway noise control and sound insulation
Authors: Ikeda Satoru , Oguchi Keiji , Nagata Minoru
Published: October 2005

The Tokyo Geijutsu Bunka-Kaikan will be the second Tokyo Metropolitan Festival Hall (Bunka-Kaikan) and is scheduled to be opened in 1990. The building has a concert hall of 1887 seats, a theater of 850 seats, two small halls, and six rehearsal rooms. The basic problem with this building is the solid-borne noise from the subway running 3 m under the site. Therefore, the subway noise estimation was a major problem at the first stage of planning. Two types of hall allocation, horizontal and vertical, were studied, considering both subway noise control and sound insulation between auditoriums. The final plan was to place the concert hall on the top floor above the theater floor. The results of the investigation of the subway noise control and sound insulation structures will be presented.
An estimation of absorption coefficients measured in a small reverberation chamber
Authors: Sato Sojun , Fujimori Takeshi , Miura Hajime
Published: October 2005

This paper describes a simple and practical technique for measuring absorption coefficients of a material utilizing a small reverberation chamber. The chamber is used as a sound insulation box as well as a chamber for a reverberant sound field. The chamber does not have an ideal diffuse sound field but a sound field just for absorption measurements. A method based on the sound intensity technique using array microphones has been adopted to measure the absorption coefficients. Many loudspeakers are arranged in the chamber in order to improve the directivity distribution of the incident sound power near the surface of the absorbing material and m simulate a random incident sound field. Theoretical and experimental considerations regarding the effect of multiple sound sources in a small reverberation chamber and regarding the dependence of measured reverberant absorption coefficients on the distribution of sound power directivity are presented.
Durational effects of syllable structure and distinctive length in Japanese
Authors: Poser William J.
Published: October 2005

The results of a study of Japanese segment durations are reported in which segment identity was tightly controlled in order to reduce the effects of intrinsic segment duration, and distinctive vowel, while consonant length and syllable structure were varied. The corpus includes words with superheavy syllables, consisting of a long vowel followed by a geminate consonant, which have not previously been studied. One surprising result is the interaction observed when the durations of the components of superheavy syllables are compared to those of cognate bimoraic syllables containing a short vowel followed by a geminate consonant. The phonological lengthening of the vowel not only increases vowel duration as expected but also causes a substantial increase (25%–33% depending on the condition) in the duration of the already long consonant. In contrast, comparison of superheavy syllables with bimoraic syllables containing a long vowel followed by a nongeminate consonant showed no consistent effect of the phonological lengthening of the consonant on the duration of the vowel. This also shows that, while the mora count may determine the total duration of the word, the increment in duration due to the addition of a mora is not realized entirely in the segment(s) which that mora contains.
On sentential effects in the control of segmental duration in Japanese
Authors: Takeda Kazuya , Sagisaka Yoshinori , Kuwabara Hisao
Published: October 2005

Mainly, only word level factors, such as the temporal compensation between neighboring segments, have been used for duration control in the speech synthesis of Japanese. In this paper, the durational characteristics of Japanese are analyzed aiming at a higher level control, which reflects also sentential effects on segmental duration. First, the word level control was formulated as a linear additive model influenced by neighboring segments, location in a word, and word length. The parameters of the formula needed to integrate these features were obtained through factor analysis on a large-scale isolated word data base (5240 words). An experiment using 216 words showed that the formula was more accurate than the conventional method. Second, focusing on sentential effects could be accomplished by comparing the predicted with the measured durations of continuous speech. The prediction errors clarified the following characteristics of sentence level duration control. (1) Prepausal lengthening is greater than ordinary word final lengthening. (2) Shorter durations are found at sentence final position in declarative sentences.
Acoustic correlates of stress in four demarcative-stress languages
Authors: Kawasaki Haruko , Shattuck-Hufnagel Stefanie
Published: October 2005

The acoustic correlates of stress in languages with “demarcative” stress (located at a fixed position relative to a word boundary) were investigated: two initial-stress languages (Finnish, Bengali) and two final (French, Hebrew). For each language, two to three speakers produced a frame sentence, then repeated it, replacing the three-syllable target word with /mamama/, /mimimi/, or /momomo/. Thirty reiterant versions from each speaker were analyzed for syllable duration, average intensity, intensity peak, intensity-duration integral, and location of f0 rise and f0 peak. It was hypothesized that initial-stress languages take advantage of higher f0 and intensity at utterance beginnings, while final-stress languages exploit the longer duration of utterance-final syllables. Results confirmed the association of longer duration with final stress but not of f0 and intensity with initial stress. Additionally, different syntactic/prosodic structures can change f0 patterns. For example, in French, one frame sentence caused f0 to rise in the last syllable, while another did not. This raises questions about the relative importance of different acoustic parameters for (a) the categorization of demarcative-stress languages, and (b) lexical versus phrasal prominence.
Acoustic characteristics of affective prosody in young children
Authors: Baltaxe Christiane
Published: October 2005

Acoustic characteristics of affective prosody in 30 children aged between 36 and 48 months, matched for SES and IQ, were measured in spontaneous and imitated utterances. Intonation patterns for neutral-normal, happy, sad, and angry affect were elicited and audiorecorded under controlled conditions. The responses were transcribed phonetically to account for speech variations relevant in the analysis. The recordings were analyzed acoustically for characteristics of fundamental frequency, intensity, duration, and their co-variation for each affective pattern using Oscillomink (Siemens) tracings and a PM pitch analyzer (voice identification). It was hypothesized that the production of affective prosody would parallel its perception. An earlier study (C. Baltaxe, Proceedings of the Sixth International Phonology Meeting, 1–7 July 1988, Krems, Austria) had shown that the same age group perceived the above affective patterns beyond chance. However, degree of success was linked to specific emotion, with a Polyanna effect toward happy emotion. The results of the present study showed that affective productions did not parallel perception, even in the imitation condition. Results are discussed with respect to articulatory control necessary for each pattern. [Work supported by Maternal Child Health.]
Ice edge noise “hot spots.”
Authors: Diachok Orest , Gruber Patricia , Mitchell Peter , Vermillion George
Published: October 2005

Previously reported and new measurements of the noise field at the periphery of the Arctic Ocean will be reviewed. Previous measurements with sonobuoys reveal that ambient noise levels are usually high at the ice edge, and that levels increase with wind speed, ice concentration, and fetch. Subsequent measurements of the noise with a towed array (by Yang et al.) indicate that the edge noise is concentrated at spatially localized (<5 km), widely separated (nominally 30 km) “hot spots.” To shed more light on this noise source and its predictability, an experiment was conducted with a towed array to probe the hot spots acoustically with a ship-towed array, and electromagnetically with an aircraft-mounted passive microwave imager, a ship-mounted radar, and satellite sensors. Results of these measurements and their implications for the predictability of hot spot locations, effective source levels, and long-range effects will be presented.
Pure-tone intensity discrimination in hearing-impaired and normal-hearing listeners
Authors: Schroder Anna C. , Nelson David A. , Viemeister Neal E.
Published: October 2005

Intensity jnd's for 500-ms tones were obtained from five cochlear-impaired and three normal-hearing subjects. The jnd-level functions, from threshold to 97 dB SPL, were measured at five test frequencies, in quiet and in high-pass noise. The “near-miss” to Weber's law was observed from normals in quiet, from two subjects with flat losses, and from regions of normal threshold in three subjects with high-frequency loss. In the same three ears, at frequencies just below and within the region of loss, jnd's conformed to Weber's law, as did the jnd's obtained in the presence of the noise for all subjects. These results are consistent with explanations of the near-miss that involve excitation at frequency regions well above the test frequency. At equal SLs, jnd's in quiet from impaired subjects were equal to, or larger than, jnd's from normals. At equal SLs, jnd's in quiet from hearing-loss subjects were sometimes smaller than normal, but were usually elevated by high-pass noise, thus implicating the near-miss. In some cases, however, jnd's at low SLs were still smaller in the noise, which may reflect the steeper rate-level functions seen in the auditory nerve in regions of cochlear loss [M. C. Liberman and N. Y.-S. Kiang, Hear. Res. 16, 75–90]. [Work supported by NINCDS Grant NS 12125.]
Demonstrations on the scattering of ultrasound by turbulence in water
Authors: Zurey Edward C. , Korman Murray S.
Published: October 2005

A beam of monochromatic sound incident on a turbulent velocity field (produced by a submerged water jet) is scattered by the velocity fluctuations in the flow. Angular measurements of the Doppler shift and spectral broadening in the received frequency spectrum of the scattered sound intensity help to characterize the mean flow and rms velocities of the turbulent field, respectively. Scattered spectra are displayed for comparison in the cases where the incident beam is generated by a point source, a plane circular array, and a focused spherical array transducer. Results are shown in an arrangement where the focused beam scans across the width of the jet. Scattering theories are briefly mentioned in light of spectral broadening results.
Sources for demonstration experiments in acoustics
Authors: Rossing Thomas D.
Published: October 2005

Many teachers, since the time of Chladni, Helmholtz, and Rayleigh, have used demonstration experiments to enhance their students' understanding of acoustical phenomena. Some sources for descriptions of suitable experiments for lecture demonstrations, corridor demonstrations, and laboratory use are discussed, as well as the author's experience with using demonstrations experiments in acoustics courses at various levels of instruction.
Acoustic source strength measurements of cavitation noise in a water tunnel
Authors: Lauchle Gerald C. , Bistafa Silvio
Published: October 2005

An experimental investigation of the noise generated by cavitation in turbulent shear flow is reported. The cavitation is produced by the flow through a sharp-edged orifice plate mounted in the test section of a 15.25-cm-diam water tunnel. The unique features of this experiment include the direct measurement of acoustic source strength using a reciprocity technique and the development of semi-empirical scaling laws for the noise produced. The source strength measurement method is useful for water tunnel cavitation noise studies because it is nonintrusive; the noise is measured by a reciprocal transducer located outside of the test section, in air. The scaling laws for orifice plate cavitation noise are developed to include the effects of pressure drop across the plate, the mean velocity through the plate, the cavitation number, and the air content level of the water. These scaling formulas were verified by running a similar test in a 30.5-cm water tunnel and comparing the measured source strength spectra to those predicted from the smaller tunnel results. [Work supported by the Applied Research Laboratory.]
Acoustical activity in structurally chiral composites
Authors: Yang S. K. , Varadan V. V. , Varadan V. K.
Published: October 2005

“Optical activity” exhibited through electromagnetic wave propagation and scattering has been well-studied in recent years even at GHz frequencies. Acoustical activity, on the other hand, was first experimentally observed in 1968 by Portigal and Burstein [Phys. Rev. 170, 673–678 (1968)]. Lakhtakia et al. [paper submitted for publication] argued that since electromagnetic waves can discriminate the chirality or handedness of the microstructure, there is no reason why other transverse waves cannot do so also. In general, the fields in an elastic solid consist of both transverse and longitudinal components. Therefore, an elastic solid can exhibit a phenomenon similar to optical activity that has been referred to as acoustic activity by some authors. To verify this hypothesis, structural chirality induced by intrinsically anisotropic materials was studied. Four laminated composite samples were prepared. In two of the samples, the fiber direction was rotated from one layer to the next so that the resulting sample was either left or right handed. In the third sample, the fiber directions were random from layer to layer, whereas in the fourth they remained aligned resulting in a sample with orthotropic symmetry. These samples were then tested by using shear wave transducers in an ultrasonic through transmission experiment. Our results indicate that shear wave transducers are able to sense the handedness of the samples and detect additional shear modes.
Energy flow associated with fundamental elastic wave types on inhomogeneous cylindrical shells
Authors: Pierce Allen D.
Published: October 2005

The basic shell dynamic equations for an inhomogeneous cylindrical shell (slowly varying radius, thickness, and material properties) result from Hamilton's principle. The version adopted here is one which yields the Donnell equations in the limiting case of a homogeneous thin shell, although the same technique applies for more sophisticated shell theories. There are three wave types that result from the theory that can be identified in the high-frequency limit as compressional (longitudinal), in-plane shear, and flexural. The propagation of these waves is directionally dependent, frequency dependent, and dispersive. The general ray acoustics formulation developed in previous papers by the author, by Felsen and Lu, and by Norris is extended to include the proper invariants for propagation along ray tubes. The energy density and energy flux vectors for each of the three wave types are derived with the aid of Hamilton's principle and a Poynting's theorem expressing conservation of wave energy is obtained for each wave type. This identification allows the discussion of the energy transfer when waves are partially reflected and converted to other wave types at ribs or at abrupt transitions of shell radius. [Work supported by ONR and by the William E. Leonhard endowment to Pennsylvania State University.]
Low-frequency problems in the determination and application of equipment sound power ratings
Authors: Baade Peter K.
Published: October 2005

There is a growing concern with low-frequency noise in buildings. Sound power ratings for the sources involved, however, typically do not include any data below the 125-Hz octave band because the present series of ANSI standards (S1.30–S1.35) and their ISO counterparts for the determination of sound power, while not setting any low-frequency limits, do not provide any information on the measurement uncertainties for frequencies below the 125-Hz octave band. In reverberation room measurements, there are at least two types of low-frequency problems: (1) difficulties in obtaining a valid space average of the sound pressure and (2) effects of the acoustic impedance seen by the source on its sound power output. The published literature on the second type contains conflicting information. This issue is important not only for standardizing equipment sound power determinations, but also for the proper application of equipment sound power ratings.
Audio spectra and related behavior of Monochamus titillator F. larvae
Authors: Walden R. T. , Nebeker T. E.
Published: October 2005

The behavior and audio spectra of Monochamus titillator F. larvae, the southern pine sawyer, were observed and measured in its natural environment. The sawyer is being utilized to assist in locating southern pine beetle infestations. The sawyer's audio emission is primarily in the 1000- to 2800-Hz range with intensity peaks at approximately 1300 and 2300 Hz. The analysis was obtained using both a sweep-frequency analyzer and an FFT spectrum analyzer. The oscilloscope display gave surprising information in that a single sound output seems to first intensify with time and then rapidly decay. A closer analysis reveals that a single sound is composed of several time decaying but ever intensifying components. The sound repetition rate varies from 30 to 120 pulses per minute depending on environmental conditions. The behavior of the sawyer during its sound production is being studied with regard to season of the year, time of day, ambient temperature, and sound production mechanism.
The effect of envelope energy on the discrimination of cross-spectral envelope phase disparity
Authors: Edwards Brent W. , Wakefield Gregory H.
Published: October 2005

The envelope cross-correlation difference Δρ can be used to predict thresholds for the discrimination of cross-spectral envelope phase disparity for modulation frequencies up to 64 Hz [Wakefield and Edwards, J. Acoust. Soc. Am. Suppl. 1 82, S41 (1987)]. For the case of two SAM carriers, Δρ is inversely proportional to depth of modulation which suggests that sensitivity to cross-spectral temporal differences depends on the degree to which carriers are modulated. Results are presented that support the hypothesis that sensitivity is inversely proportional to envelope energy. Thresholds are obtained and Δρ's calculated for SAM carriers of varied modulation depths. It is found that Δρ for a complex sinusoidal modulator is equal to that for a single sinusoidal modulator when the energies of the two modulators are equal. This relationship is also observed for envelopes of narrow-band noises. In contrast, other measures of envelope fluctuation do not yield constant performance as measured by Δρ. [This research was supported by a grant from the AFOSR.]
Effects of flanking band proximity, number, and modulation pattern on comodulation masking release
Authors: Hall J. W. , Grose John H.
Published: October 2005

Comodulation masking release for a 700-Hz pure-tone signal was investigated as a function of the number and spectral positions of 20-Hz-wide comodulated flanking bands. The number of flanking bands ranged from one to eight. The results indicated (1) an effect of proximity, where bands closer to the signal resulted in larger masking release, and (2) an effect of number of bands, where more bands gave rise to larger CMR. Two further sets of conditions were examined, and compared to the condition where all eight comodulated flanking bands were present: In one set of condilions, two of the eight flanking bands were removed; in the other set of conditions, two of the eight flanking bands were replaced with bands that were not comodulated with respect to the other bands. There was very little effect of removing two of the bands, even when close to the signal frequency; however, CMR was substantially reduced when the noncomodulated replacement bands were introduced. These results indicated that the auditory system is not able to disregard modulations on flanking bands that differ from the modulation pattern on the signal band, particularly if these bands are close in frequency. [Research supported by AFOSR.]
Contingencies in stress patterns and syllabic nuclei: Lessons for searching lexical databases
Authors: Smith Mary R.
Published: October 2005

In automatic speech recognition programs, attempts have been made to use partial information about the phonetic structure of signals to search large lexical databases. Little attention has been given to the interaction of stress patterns and syllabic nuclei in restricting the searches. A survey of the MRC Psycholinguistic Database of British English (RP) with 38-K tokens revealed that six stress patterns (out of 17 attested) account for 96% of the tokens in the subset of two- and three-syllable words. Further, three syllabic nuclei (out of 23 attested) account for 50% of the tokens, independently of stress pattern. The interactions of stress pattern and nuclei show not only increased discriminatory power (in information theoretic terms) over either attribute alone, but also reveal significant gaps between expected and observed cases. The gaps, both accidental or principaled, further reduce the relevant search spaces and increase the usefulness of this type of partial information over other candidates. [Work supported by Alvey Grant MMI 069.]
The Delta System, version 2: A tool for testing phonological and phonetic theories
Authors: Hertz Susan R.
Published: October 2005

The Delta System is a software system that lets linguists test the relationships of phonological and phonetic units through speech synthesis [J. Acoust. Soc. Am. Suppl. 1 75, S60 (1984)]. The Delta programming language now has an improved syntax with greater appeal to linguists, along with a variety of new features. For example, it has new constructs for manipulating and testing Delta's multilevel utterance representation, for preventing groups of rules from crossing particular linguistic boundaries, and for specifying the timing of phonetic events with respect to higher level linguistic units. The Delta debugger now lets users step through their programs statement by statement, and interactively modify their utterance representation on the fly (for example, to hear the effect of a longer duration). A macroprocessor lets users tailor the syntax of Delta programming language statement and debugging commands to their liking. The system complies Delta programs into C programs and lets users intermingle Delta and C statements. The system will be available for demonstration.
Consequences of new and old information on the production of grammatical categories
Authors: Charles-Luce Jan
Published: October 2005

A recent study [C. A. Fowler and J. Housum, J. Mem. Lang. 26, 489–504 (1987)] demonstrated that talkers distinguish second (old) token productions from first (new) token productions through shortening. Moreover, listeners could use this information to identify old from new tokens. Of interest for the present investigation was the finding that topic words shortened relatively less. Thus talkers appear to treat certain types of information differentiately. To investigate this idea further, the present study examined four grammatical categories and a fifth topic noun category when these were produced as old and new information. To determine talkers' sensitivity to new versus old information, two passage types were constructed: coherent (paragraph of related sentences) and noncoherent (paragraph of unrelated sentences). The results show that duration does not decrease from new to old productions for all grammatical categories. However, this finding is not independent of passage type. Implications of these results for talkers' sensitivity to semantic information will be discussed. [Work supported by NIH Grant NS-12179 to Indiana University.]
On-line measures of comprehension of natural and synthetic speech
Authors: Ralston James V. , Mullennix John W. , Greene Beth G. , Lively Scott E.
Published: October 2005

Accumulated perceptual research comparing natural and synthetic speech indicates relatively large differences in tasks assessing acoustic-phonetic processing, and small differences in tasks assessing higher levels of processing related to comprehension. Studies comparing comprehension of passages of fluent natural and synthetic speech have generally examined performance on questions presented after subjects have listened to a passage. Such postperceptual measures are known to be relatively insensitive to differences in “real-time” processing operations. The present investigation employed an “on-line” measure of processing, i.e., word monitoring, to study comprehension. Subjects in these studies were presented with three types of passages—(1) natural speech, (2) high-quality synthetic speech, and (3) low-quality synthetic speech—and were required to monitor for target words as well as verify postperceptual comprehension questions. Monitoring latencies and verification performance will be discussed in terms of differences in perceptual processing and comprehension of natural and synthetic speech. [Work supported by NSF.]
Detailing the nature of talker variability effects in speech perception
Authors: Mullennix John W. , Pisoni David B.
Published: October 2005

Previous studies have shown that changes in a talker's voice from stimulus to stimulus affect the perception and recall of spoken words [see Mullennix et al., J. Acoust. Soc. Am. 85, 365–378 (1989); Martin et al., J. Exp. Psychol. Learn. Mem. Cog. (in press)]. In the present study, the perceptual consequences of talker variability were investigated in further detail. In order to assess the relative magnitude of intratrial versus intertrial changes in a talker's voice, a same-different reaction time judgment task was used. Performance was compared across three talker conditions: single talker, multiple talker across trials, and multiple talker within trials. In addition, the effects of talker variability over time were examined by observing performance across varying ISI delays. The results obtained provide further information about the nature of talker variability effects in the perception of spoken words and will be discussed in terms of their relationship to perceptual normalization processes in speech perception. [Work supported by NIH.]
Efficient simulation of the vertical structure of noise using the parabolic equation
Authors: Evans R. B. , Carey W. M. , Botseas G. , Davis J. A.
Published: October 2005

The structure of noise at a vertical array in a range-dependent ocean basin can be simulated using the parabolic equation (PE). Noise sources are distributed throughout the basin. The PE can be used to compute the field at the array due to each of the sources. The response of the array to the superposition of these noise sources is found by beamforming. The number of PE runs can be reduced by using the elements in the array as sources and relying on reciprocity, but even this indirect approach is impractical. An efficient and direct approach is to start at a distant noise source and superimpose additional noise sources on the PE field as the field is marched toward the array. Only one PE run is needed in a cylindrically symmetric ocean basin. The justification for this approach is discussed. An application demonstrates that noise at the horizontal can be caused by slope conversion of low-frequency noise sources over the basin boundaries. [Work sponsored by NUSC.]
Frequency-averaged, mean-squared coherence of simulated underwater explosive transients
Authors: Leybourne Allen E.
Published: October 2005

A method has been developed for determination of the frequency-averaged, mean-squared coherence (FMSC) of broadband transient acoustic signals, similar to underwater explosions. It has many of the properties of the more conventional mean-squared coherence (MSC), including a systematic bias, dependent upon the number of spectral values used in the estimate. The method has been demonstrated using a model of the underwater explosive direct arrival transient signal. As FMSC is averaged over several frequencies the method compromises the functional knowledge of frequency dependence to achieve stable and relatively unbiased values. Results are compared to MSC, utilizing a calibration method developed during the study. The relative level of coherence between separate similar transient acoustic processes can be determined when the signals are precisely time aligned. FMSC can be used as the means of making this time alignment, thus making the necessary computations internally consistent. [Work supported by U.S. Navy, NORDA, Code 242, Arctic Acoustics.]