bluuebunny/crossref_metadata_2025 huggingface dataset:
Models for voicing and aspiration in stop consonants
Authors: Stevens Kenneth N.
Published: October 2005

A theoretical analysis of sound production for voiceless and voiced stop consonants has been carried out. The analysis includes the effects of active and passive (in response to intraoral pressure changes) expansion or contraction of the pharyngeal volume, active and passive changes in glottal configuration, the generation of periodic glottal vibration and aspiration noise, and the generation of transient and frication noise sources at the consonantal release. Both monopole and dipole components of the turbulence noise sources are considered. The model is used to calculate the absolute sound-pressure levels and spectra for the various components of the radiated sound for labial, alveolar, and velar stops. The predictions of the model are in reasonable agreement (within a few dB) with data from spoken syllables. Procedures for estimating the characteristics of turbulence noise sources still need to be refined, particularly the distribution of the sources downstream from a glottal or supraglottal constriction. The model can be used to infer details of the time course of supraglottal and laryngeal constrictions based on data from fine-grained acoustic analysis of utterances. [Research supported in part by NIH Grant DC00075.]
Glottal waveform characteristics of deaf speakers
Authors: Mahshie James J.
Published: October 2005

The distinctive voice quality that characterizes many deaf individuals suggests that they use phonatory adjustments for speech production that differ from normal. Little research, however, has been reported that examines the phonatory attributes of deaf individuals. The purpose of the present work was to examine glottal volume velocity waveform characteristics of deaf speakers, and to compare these characteristics to those of normal-hearing talkers. The oral airflow signals associated with non-nasalized vowels produced by five deaf and five normal-hearing subjects were inverse filtered, and the resultant signals examined. In addition to qualitative waveform descriptions, measures were made characterizing cycle-to-cycle peak volume velocity, duty cycle characteristics, and amount of unmodulated airflow (do offset of the volume velocity signal). Result thus far reveal systematic differences from normal for some of the deaf speakers, while others, particularly those with voice quality perceived as less aberrant, had glottal waveform patterns similar to those observed in the normal-hearing subjects. Procedural issues for obtaining and analyzing the glottal waveforms of deaf individuals, and the implications of the findings of speech intelligibility and naturalness of deaf speakers, will be discussed. [Work supported by the Whitaker Foundation.]
Differentiation and variability of tongue positioning in the production of German vowels
Authors: Bohn Ocke-Schwen , Flege James E. , Dagenais Paul A. , Fletcher Samuel G.
Published: October 2005

Tongue-palate distances in repeated productions of German vowels were measured using glossometry. A male native speaker from northern Germany produced 10 tokens each of the 15 stressed monophthongs of German in the carrier phrase ob er /bVp/ habe. Tongue configurations for pairs of vowels were considered sufficiently differentiated if the mean (unsigned) distance between tongue positions exceeded 1.0 mm. For seven pairs of German vowels, tongue positions were not clearly differentiated. American English vowels, however, were produced with nonoverlapping tongue configurations in a related study [Flege et al., Lang. Speech 29, 361–388 (1986)]. The difference between English and German may be largely due to the different mechanism used by these languages to differentiate their large vowel inventories. The overall mean s.d., associated with 10 repetitions for the 15 target positions was 0.8 mm. This measure of variability of tongue positioning is virtually the same as for American English and Spanish vowels in previous studies [J. E. Flege, Lang. Speech 32, 123–147 (1989)], suggesting that neither differences in inventory size nor different mechanisms used to differentiate large vowel inventories affect the precision of tongue positioning. [Work supported by NIH Grant 20963.]
Three-dimensional reconstruction of the palate and tongue during the production of sustained vowels
Authors: Watkin Kenneth L.
Published: October 2005

The purpose of the present investigation was to reconstruct the three-dimensional (3-D) shape of the oral cavity during the production of sustained vowels. Using a specially developed palatal tracing wand and ultrasonic transducer localization device, real time convex phase array images of the tongue were digitized and stored on an IBM PC/AT along with the 3-D shape of the palate. The reconstructed 3-D shapes of the tongue surface relative to the 3-D shape of the palate will be presented. Data analysis strategies will be discussed along with implications for speech articulatory modeling.
Laboratory scale measurements of low-frequency underwater sound propagation over a sediment layer with a hard basement
Authors: Hundley Allen J. , Gegg Stewart A. L.
Published: October 2005

Recent measurements of low-frequency sound propagation in a region where a thin sediment layer overlays a hard rock basement [Hughes et al., J. Acoust. Soc. Am. 88, 283–297 (1990)] showed high transmission losses at certain frequencies, which were not well predicted using a SAFARI prediction code. It was suggested that the high transmission loss levels were caused by resonances in the sediment layer. This paper will describe laboratory measurements in a similar environment using a model whose scale was ∼ 1/1000th of the ocean experiment. The sediment was modeled using a layer of epoxy of uniform thickness on a concrete base, and transmission loss was measured as a function of depth range and frequency. High transmission losses were found at low frequencies which have similar characteristics to those observed by Hughes et al. at full scale. This paper will describe the observations of the sound field at low frequencies and compare the measurements with predictions made using SAFARI.
Sound propagation conditions in the equatorial South Pacific Ocean
Authors: Browning David G. , Denham Ronald N.
Published: October 2005

A major part of the South Pacific Ocean is impacted by a cold water circulation induced by the Antarctic Circumpolar Current. This results in either a double or a very broad deep sound channel axis [R. N. Denham et al., J. Acoust. Soc. Am. 81, 787–789 (1987)]. However, nearer the equator this impact is reduced and a series of equatorial currents and counter currents come into play. An analysis is made of existing oceanographic data to determine the resulting sound-speed profile shape and sound channel axis depth. A comparison is made to profiles from the temperate regions of the South Pacific Ocean.
Recollections of a contemporary of Laurence Batchelder, concerning “Preferred reference quantities for acoustic levels, ISO 1683–1983.”
Authors: Young Robert W.
Published: October 2005

Laurence Batchelder became a member of the Acoustical Society of America in 1946, having already been employed by the Submarine Signal Company for 17 years in the development of underwater SOund NAvigation and Ranging equipment. He was a strong and successful proponent of referring an acoustical level to one unit of the Systéme International as illustrated in the following. In 1946, sound-pressure level in water at a stated distance from a SONAR projector was typically referred to 1 dyn/cm2; sound-pressure level radiated by a submarine was typically referred to 0.0002 dyn/cm2; sound-pressure level in air measured by a standard sound-level meter was referred to 0.0002 dyn/cm2. At a request of the U. S. Navy in 1961, American Standards Association Working Group SI-44 was appointed to propose reference quantities for acoustical levels. After much negotiation, S1. 8-1969 was approved, including a new reference pressure 10−5 dyn/cm2 = 1 micropascal (μPa) for liquids; 2 × 10−4 dyn/cm2 = 20 μPa was retained as the reference for gases. Also in 1961, when the British Standards Institution held the Secretariat for Technical Committee 43, Acoustics, of the International Organization for Standardization (ISO), the Netherlands Member Body proposed that the single reference pressure for sound-pressure level in all gases and fluids be 2 × 10−5 N/m2 = 20 μPa. After a 12-year succession of drafts and ballots, during which the BSI relinquished the Secretariat for TC43 to Denmark, a new Working Group 43-14 was appointed whose effort culminated in ISO 1683–1983; 20 μPa was confirmed as the reference pressure for air, and 1 μPa was standardized for media other than air. The goal proposed by The Netherlands in 1961—only one reference pressure for sound-pressure levels in all gases and fluids—has not been attained.
Perception of vocal pitch vibrato in short tones
Authors: d'Alessandro Christophe , Castellengo Michele
Published: October 2005

Two different experiments were carried out to examine the perception of short vibrated tones, using synthetic stimuli. A preliminary experiment on long tones showed results identical to those obtained by Shonle and Horan [J. Acoust. Soc. Am. 67, 246–252 (1980)]. The first experiment used a method of adjustment to find the pitch of the vibrated tones, according to their durations (or equivalently, to the number of vibrato cycles). Durations from 80 ms (half-cycle for a vibrato rate of about 6 Hz) to 320 ms (two cycles) where studied. The results indicate that an averaging of F0 excursion is performed, and that perception may be ambiguous above a threshold of duration, called herein “threshold of fusion.” The second experiment used a constant method to estimate the threshold of fusion, defined as the fractional number of cycles where a stimulus is integrated into one tone. Above this threshold, a glissando or two consecutive tones are perceived. The threshold was estimated to be at about the second third of a vibrato cycle beginning at zero phase. It was noticeable that in the first experiment, the subjects were still able to assign a unique pitch to the stimuli above the threshold when the tone is long enough. A concluding discussion points out how these psychoacoustic results may contribute to our understanding of pitch perception for vibrato tones in actual musical performance and explain some aesthetic values governing the production of vibrato by singers.
Sharpness measurements for musical instrument timbres
Authors: Goad Pamela
Published: October 2005

The timbres of string and woodwind families were investigated by measuring sharpness and loudness over a 2-octave range and between individual performers. Sharpness is defined as a frequency-dependent weighting of the loudness-critical band rate pattern. It is promising for timbre perception research because it addresses the most salient timbral dimension. Digital recordings were collected with performers 4 m from the microphone in a music rehearsal hall. Performers played diatonic scales at two extreme musical dynamic levels, pianissimo and fortissimo. Across all families, sharpness increases with playing frequencies and with dynamic level, and lies between 0.5–2.0 acums. Loudness variance is larger than sharpness variance. Overlap in sharpness is greatest at the pianissimo levels with the exception of the double reeds. The string family smoothly changes in sharpness across the entire playing range at both musical dynamics levels. The clarinet family has less overlap at the fortissimo level and a slight increase in sharpness for lower pitches. Double reeds exhibit the greatest variance in sharpness. Performer-specific variations are evident, but the general trends in sharpness remain the same.
Hysteresis in the perception of directional pitch change
Authors: Tuller Betty , Giangrande Janice
Published: October 2005

It has long been known that pairs of complex tones that are clearly different in pitch may be ambiguous as to the direction of the difference [e.g., R. N. Shepard, J. Acoust. Soc. Am. 36, 2346–2353 (1964)]. The present experiment explores whether the ambiguity in pitch change perception results from the dynamic nature of the perceptual states. Twelve stimulus tones were generated, each 120 ms in duration, and each composed of 10 sequential, harmonically related sinusoidal components. The 12 tones differed by a chromatic step change of the 10 components. Tone pairs consisted of a standard complex tone (D♯) followed by one of the other 11 tones. Three conditions were used: (1) randomized presentation of the tone pairs; (2) tone pairs in which the comparison tone increased by one chromatic step in successive tone pairs (1 vs 2; 1 vs 3; etc.); and (3) tone pairs in which the comparison tone decreased by one chromatic step in successive tone pairs (1 vs 12; 1 vs 11; etc.) Consistent with previous reports, when the tone comparisons were randomized the direction of perceived pitch change was ambiguous as the frequency change neared the half-octave. Signature properties of nonlinear dynamical systems (hysteresis effects and bistability) were observed in conditions 2 and 3, for all subjects. Specifically, the region of ambiguity shifted markedly as a function of the ordering of tonal comparisons. Implications for geometric models of pitch perception will be discussed. [Work supported by NIDCD and NIMH.]
Detection of temporal perturbations in a mechanical music performance: Lengthening is more difficult to detect where it makes musical sense
Authors: Repp Bruno H.
Published: October 2005

Twenty musically literate listeners were repeatedly presented with the first eight bars of a Beethoven minuet, realized with physically regular timing on an electronic piano. On each trial, one of the 47 consecutive eighth-note intervals in the piece was lengthened by a small amount, and the listeners had to mark its location with reference to the score. The resulting detection accuracy profile across the whole musical excerpt showed dips in the places where lengthening would typically occur in an expressive performance. The correlation with the measured timing profile of a particular expert performance (Murray Perahia) was − 0.59 (p<0.001). Thus a psychophysical task (detection of temporal irregularity) can engage listeners' performance expectations and reveal the inherent temporal dynamics of substantial music. [Work supported by BRSG.]
The prediction of sound-pressure levels outdoors in the Federal Republic of Germany
Authors: Nolle Alfons
Published: October 2005

In the Federal Republic of Germany the VDI Guidelines 2714 and 2720/2 are used for the prediction of sound-pressure levels in the neighborhood of sound sources. These guidelines were developed about 20 years ago and they describe a general frequency-dependent calculation method for sound propagation outdoors under downwind conditions and for different sound sources, mainly industrial plants. Simplified prediction schemes for road and railway traffic have also been derived from the VDI guidelines. The calculation method will be presented. The development of the guidelines have been supported by research work in sound propagation outdoors mainly above soft ground. It will be shown that the calculation methods of the guidelines are able to predict the A-weighted sound-pressure level, which is used in Germany for rating purposes, for the usual situations in the neighborhood of the sound sources. For sound propagation over mainly hard ground, which is a rare case in noise control, nearly no information exists in Germany.
Geometrical ray acoustic model in the case of a linear sound-speed profile for outdoor sound propagation
Authors: L'Espérance André
Published: October 2005

To estimate the effects of temperature, wind, and atmospheric turbulence on the outdoor sound propagation, a heuristic model based on the geometrical acoustic approximation has been developed. This model assumes a constant linear sound-speed gradient, which allows an analytical determination of the direct and reflected curved ray paths and of all the possible additional rays that may appear between a source and a receiver over the ground in presence of a positive sound-speed gradient. The total sound pressure at the receiver is computed by summing the contribution of all the partially coherent rays. In presence of a negative sound-speed gradient, the receiver may be located in the shadow zone. In that case, the sound-pressure level at the receiver is evaluated with the diffraction solution proposed by Berry and Daigle [J. Acoust. Soc. Am. 83, 2042–2058 (1988)]. Experimental results found in the literature for wind speed gradient and experimental results obtained during summer 1990 for temperature gradient will be presented and compared with the model.
Gaussian beam method for computing outdoor acoustic fields
Authors: Gabillet Yannick
Published: October 2005

Recently, a method using superposition of Gaussian beams has been proposed in the seismological community for the solution of high-frequency wave problems [V. Cerveny et al., Geophys. J. R. Astron. Soc. 70, 109–128 (1982)]. The concept of the theory of Gaussian beams is to solve the wave equation in the neighborhood of the familiar rays by use of the parabolic approximation. The solution associates with the ray a beam with a Gaussian amplitude profile normal to the ray. The approximate global solution for a given source is then constructed by a superposition of Gaussian beams along nearby rays. The method has been applied to typical outdoor sound propagation problems: wind and temperature gradient effect, turbulence effect, diffraction by screen. Comparison with measurements performed in a wind tunnel and with other results of the literature show that the Gaussian beam method is a potentially useful approach.
A simple exact solution for a point source above a reacting surface
Authors: Di Xiao , Gilbert Kenneth E.
Published: October 2005

An exact analysis is developed for a spherical source in air above a reacting surface. The solution, which is valid for both local and extended reaction, proceeds along the standard route of an expansion of the spherical wave as a superposition of plane waves. Use of a Laplace transform on the plane-wave reflection coefficient leads to a final form that requires a simple numerical integration of an image integral. The resulting solution is exact for all angles of propagation. For a locally reacting ground surface, the image integral is rapidly convergent. A number of limiting cases are investigated and compared with previous solutions. [Work supported by NASA.]
Traffic noise prediction from motorways and fast roads
Authors: Garai M. , Cocchi A. , Fausti P.
Published: October 2005

A generalized prediction method is presented that has a flexibility that meets the complexity of the Italian laws. The method relies on a computer program that, via an interface with a database, can analyze several measurements taken in the land around a road and compare them to the theoretically predicted noise levels (an improved version of the RLS-81 algorithm is used); the best correlation between the two sets of values can then be enclosed in the prediction algorithm. Thus the program can adapt itself to those site-dependent characteristics that no model can account for. The program can then be utilized to perform all the usual computations, including barrier insertion loss estimates, and to generate noise contour maps. Details will be given about the study of a critical by-pass/motorway surrounding the town of Bologna; this study permitted a thorough check of the program, which was found to be reliable and very easy to use.
Derivatives of the phase change on reflection from plates: A new analysis of resonance
Authors: Lenoir O. , Izbicki J. L. , Conoir J. M.
Published: October 2005

Recent experimental works have yielded a renewal of interest on the study of the phase of the scattered pressure by elastic bodies. Recent results, pointed out by Conoir about cylindrical shells, have led the authors to be particularly interested in the derivatives of the phase of the reflection coefficient of an elastic plate, with regard to the longitudinal, shear, and outer liquid velocities, as well as to the frequency. Three theoretical studies have been carried out: The first one consists in calculating the whole derivatives of the phase versus the frequency; the second one in calculating the derivatives versus the parameter chosen to derive the phase; and the third one in calculating the derivative, with respect to the frequency, versus the velocities. The goal is to exhibit the influence of these parameters on the phase when a Lamb mode is excited in an elastic plate. Indeed, the different curves obtained give information about the prevailing character, longitudinal or shear, of the waves related to Lamb modes. They also determine whether a mode is well coupled or poorly coupled with the external medium.
Influence of onset cues in lateralization
Authors: Freyman Richard L. , Zurek Patrick M.
Published: October 2005

When pairs of clicks delivered binaurally via earphones are repeated to form a click train, interaural cues at stimulus onset can exert a strong influence on the perceived intracranial position of the entire stimulus [Saberi and Perrott, J. Acoust. Soc. Am. Suppl. 1 86, S11 (1989)]. This phenomenon has been observed most clearly under conditions in which the interaural time delays in the ongoing click trains—because they alternate between two values—are ambiguous. For example, when a single click pair with a 500-μ-time lead to the right is followed by a 250-ms train consisting of alternating diotic and left-leading click pairs, the entire stimulus is lateralized to the right. This paper will describe conditions in which onset cues dominate the perceived lateral position as well as those in which steady-state cues determine the lateralization. It will also describe stimulus manipulations that appear to produce a release from the influence of the onset cues. For example, a brief silent gap inserted in the middle of a click train released the listener from the influence of the original onset, while a brief burst of binaural white noise presented during the middle of the click train did not. [Work supported by NSF and NIH.]
Assessing the role of FO in vowel perception via linear logistic modeling
Authors: Nearey T. M. , Andruski J. E.
Published: October 2005

Logistic models provide powerful tools in evaluation of stimulus-response relationships in speech perception [T. Nearey, J. Phonet. 18, 347–373 (1990)]. Excellent fits result when such models are applied to vowel perception data. These models allow insight into the possible normalizing role of F0 in vowel perception. If (as in many current perceptual accounts) the role of FO is restricted to an additive formant normalization factor (for some nonlinear transform of the frequency axis), then optimized logistic models using formant frequencies and the fundamental as predictors should show certain specific patterns of correlation among certain estimated parameters across vowel categories. Preliminary results from the analysis of data in these laboratories indicate that this is indeed the case. Furthermore, FO normalization appears to occur nearly independently in “head” and “tail” sections of “hybrid” syllables, where, e.g., the ending portion of a syllable from a male speaker is spliced (following a period of silence) to the beginning portion from a female. [Work supported by SSHRC.]
Effects of lexical status on perceptual organization in duplex perception
Authors: Nygaard Lynne C.
Published: October 2005

Duplex perception occurs when a synthetic syllable is split so the third-formant transition is presented to one ear and the rest of the syllable (the base) is presented to the other ear. Listeners report hearing two distinct percepts — a complete syllable in the ear with the base and a nonspeech chirp in the ear with the transition. A modification of this duplex phenomenon can be created by presenting a third-formant transition in isolation to one ear and the same transition electronically mixed with the base to the other ear. In this case, the transition information fuses to form a chirp percept in the center of the head and the syllable in the other ear becomes clearer than the one produced with the standard duplex procedure. Nygaard [J. Acoust. Soc. Am. Suppl. 1 87, S71 (1990)] found that when the spectral composition or onset frequency of the isolated transition was varied relative to the complete syllable base, both phonetic integration and nonphonetic fusion remained remarkably intact even with large differences in spectral composition between components. In a series of experiments, the lexical status of the syllable base was varied to determine the effect of lexical information on perceptual organization of acoustic components that differ in spectral composition. It was found that the lexical status of the eventual phonetic percept influenced the phonetic integration of acoustic components into syllable percepts, but had no effect on fusion of the third-formant transitions to create a centered chirp percept. These results suggest that lexical information contributes to the perceptual grouping of acoustic components into phonetic percepts.
The role of transition duration in the perception of speech and nonspeech analogs of place of articulation
Authors: Zakin Reneacute;e A. E. , Aslin Richard N.
Published: October 2005

A previous report [R. Zakia, J. Acoust. Soc. Am. Suppl. 1 87, S117 (1990)] demonstrated that at a formant frequency pattern ambiguous between alveolar and velar, subjects identify synthetic speech stimuli with longer transition durations as velars and stimuli with shorter transition durations as alveolars. These results suggest the operation of either (1) an articulatory property characteristic of velars (longer transition durations distinguish velars because of their slower articulatory release), or (2) differential perceptual sensitivity to transition duration for spectral patterns characteristic of velars. To evaluate these possibilities, nonspeech analogs of a formant pattern ambiguous between an alveolar and a velar were generated with transition durations ranging between 20 and 50 ms in 5-ms steps. In contrast to the previous identification task, the nonspeech stimuli were presented in a same-different discrimination task. For comparison purposes, this same-different task was also conducted with the speech stimuli. Transition duration was an effective cue to discrimination of both speech and nonspeech stimuli, suggesting that the link to articulatory mechanisms is not essential. However, discrimination performance for the speech stimuli was generally poorer than for the nonspeech stimuli, suggesting that the link to articulatory mechanisms is not essential. However, discrimination performance for the speech stimuli was generally poorer than for the nonspeech stimuli, suggesting either that within-category judgments are more difficult to make for broadband signals or that perception of the speech signals as phonetic segments interferes with auditory discrimination.
Multiple source behavior of passive synthetic aperture algorithms
Authors: Edelson Geoffrey S. , Sullivan Edmund J.
Published: October 2005

Generally speaking, passive synthetic aperture algorithms involve the calculation of a single phase correction factor from snapshot to snapshot in order to compensate for the spatial movement of the array over time. Within a given frequency bin and for sources in the far field, this approach is shown to be sufficient for the case of any single source and for the case of two completely deterministic (fully coherent) sources. However, for any other scenario, such as one deterministic and one stochastic source, this technique is shown not to result in the desired phase correction factor. This is a direct consequence of the algorithms used in the various passive synthetic aperture techniques. After reviewing these techniques, an approach to the resolution of this problem, which is based on the multivariate maximum likelihood method, is presented.
Vibrotactile adaptation
Authors: Hollins Mark , Goble Alan K. , Delemos Kimberly A.
Published: October 2005

Perception of a vibratory test stimulus is substantially influenced by the level of vibrotactile stimulation that precedes it. In a series of experiments reported here, effects of such adaptation on detection and discrimination thresholds were examined. All stimuli were sinusoidal vibrations delivered perpendicular to the skin through a flat, circular contactor; thresholds were measured during “probe” test periods separated by adapting periods. Absolute thresholds showed a negatively accelerated rise following onset of the adapting stimulus, on both the hand and the face. In contrast to the fact that receptoral channels serving the hand adapt independently of one another [R. T. Verrillo and G A. Gescheider, Sens. Proc. 1, 292–300 (1977)], some evidence was found for channel interaction on the face, a result implying central nervous system (CNS) involvement. Amplitude difference thresholds, measured on the hand with two-interval forced-choice tracking, decreased following exposure to adapting stimuli comparable in amplitude to the test stimuli; this finding is consistent with data [G. A. Gescheider and G. H. Wright, J. Exp. Psychol. 77, 308–313 (1968)] showing that the psychophysical function is steeper after adaptation. A recently proposed model of somatosensory cortical dynamics [B. L. Whitsel et al., in Information Processing in the Somatosensory System, edited by O. Franzen and J. Westman (MacMillan, London, 1990)] offers a plausible physiological context for understanding these results. [Work supported by USPHS Grant No. DE-07509.]
Representation of spatial patterns on the Optacon in the peripheral and central nervous system
Authors: Gardner E. P. , Palmer C. I. , Hamalainen H. A. , Warren S.
Published: October 2005

The pattern of neuronal activity evoked by the Optacon stimulator has been defined for cutaneous mechanoreceptors and for cortical neurons using bar patterns scanned across the tactile array. Pulses of 4 ms were delivered at 25–100 Hz in a row-by-row sequence stimulating motion of a horizontal bar along the finger. These stimuli activated only phasic mechanoreceptors (RA and PC afferents) but not slowly adapting afferents. RA afferents view only a small fraction of spatial patterns, as they respond to only 2–4 adjacent rows, firing one spike/pulse. Responses are all or none, and constant throughout the period of stimulation. Resolution of stripe spacing appears limited by the receptive field diameter. Total spike output is constant at all frequencies tested, and average firing rates mimic the stimulation frequency. Central neural networks transform the peripheral input such that S-I cortical neurons show a linear rise in total spike output and constant average firing rates as the interpulse interval is lengthened from 10–40 ms. Firing is higher than the stimulation rate at 25 Hz, and reduced to half the input frequency at 100 Hz, suggesting amplification at low Hertz and inhibition at high Hertz. Stimulation rates are represented by the pattern of firing within the spike train, but the modulation amplitude is frequency dependent. It is suggested that the low-amplitude continuous firing observed at 100 Hz correlates with sensations of smooth motion across the finger, while the large fluctuations in neural excitability at 25 Hz yield distinct, punctate sensations. [Work supported by NS11862.]
Acoustics of the glass harmonica
Authors: Rossing Thomas D.
Published: October 2005

Modern glass harmonicas have developed along two different lines: One type consists of a collection of wineglasses, which the player sets into vibration by moving a finger around the rim. The other type, called the armonica by its inventor Benjamin Franklin, consists of a series of glass bowls mounted on a horizontal shaft so that they rotate together. The vibrational modes of a glass harmonica are quite similar to those of a bell, the fundamental (2,0) mode determining the pitch. The tangential component of motion in this mode (which is 1/2 the normal component) is apparently excited by stick-slip coupling to the moving finger of the player. Simple theory predicts that the frequency will increase as t/r2, where r is the radius of the glass, and t is its thickness [T. D. Rossing, Phys. Teacher 28, 582–585].
The glass harmonica: A return from obscurity
Authors: Finkenbeiner Gerhard , Meyer Vera , Nakashian Alisa
Published: October 2005

The authors introduce the glass harmonica by placing it in its historical context. It is explained how, after more than a century of obscurity, the glass harmonica has been recreated using updated methods and materials. Specific features of the instrument are examined, including its adaptability to a wide range of compositional works.
The glass flute as an evolutionary step between wood and metal
Authors: Sheldon Robert E. , Stern Sara , Corliss Edith L. R.
Published: October 2005

In the course of development of flute tone, the material of which the flute was made became an important consideration. The upper harmonic structure is affected both by the shape of the instrument and by the material of which it is made. Modern flutes are made of dense and rigid metals. Along the way, a few 19th-century instrument makers made flutes of glass. The physical properties of glass flutes will be discussed and demonstrated.
Interior pressure field in an accelerated spherical container
Authors: Morfey Christopher L.
Published: October 2005

The pressure field inside a rigid hollow container, filled with uniform fluid and subjected to an impulsive translational acceleration a(t), is examined analytically by time-domain methods. In the incompressible limit, a uniform pressure gradient −ρa(t) exists throughout the interior. However, compressibility introduces acoustic wave phenomena, which are investigated in detail in this paper for a spherical container. The exterior version of the problem is discussed by Pierce, and a solution given, in his book [A. D. Pierce, Acoustics (1982)]. The present interior problem has received some attention in the biomechanics literature, as a step toward modeling the dynamics of closed-head injury: In this context, it describes events on a short time scale, of order 20 μs rather than 20 ms (which is the typical impact duration in blunt head trauma).
Thermoacoustic properties of porous media
Authors: Koren Alon , Ceperley Peter H.
Published: October 2005

The thermoacoustic time constant and flow resistance were measured for steel wool, sand, and a parallel plate geometry over a range of frequencies in one atmosphere of air. The results are compared with that of the theoretical parallel plate geometry. Suitability of various packings for thermoacoustic applications will be discussed. [Work supported by ONR.]
Observation of a second soundlike mode in superfluid-filled aerogel
Authors: McKenna M. J. , Slawecki Tania , Maynard J. D.
Published: October 2005

Superfluid He4 is interesting acoustically because it can support more than one mode of sound propagation, and these modes may be used in combination to determine the critical properties of the superfluid. Recently, there has been considerable interest in the critical behavior of superfluid He4 in the presence of a random potential field provided by highly porous media, specifically, silica aerogels whose porosities exceed 90%. Unlike other porous media, where the normal fluid is clamped to the rigid matrix, these aerogels are highly compliant, and while the normal fluid remains locked to the aerogel matrix, both the matrix and the normal fluid can move in response to mechanical and thermal gradients. Therefore, one would not observe ordinary fourth sound but rather a sound mode intermediate between first and fourth sound. In addition, the superfluid can move in a direction opposite to the normal fluid/aerogel matrix, resulting in a second soundlike mode. The first experimental observation of this second soundlike mode in superfluid-filled aerogel is reported, and it is shown that it remains a high-quality mode near the critical temperature. Also presented are measurements of the sound mode intermediate between first and fourth sound, and a theoretical model that gives good agreement with the observed new sound modes. [Work supported by NSF Grant DMR 9000549 and the Office of Naval Research.]
Underwater audiological testing of a diver communicator
Authors: Ranlet Richard W.
Published: October 2005

An underwater communicator was developed to evaluate the suitability of direct audio voice transmission as a practical means to enable close-range communications between divers using open-circuit SCUBA. A communicator that transmits speech directly into the water was designed and human engineered to yield a practical working prototype suitable for normal open-water dive conditions. Intelligibility testing of the device entailed underwater audiological testing that attempted to match in-air standards and practices. Measurements of hearing thresholds, speech reception thresholds, and speech discrimination/recognition were performed using accepted ASHA practices. Intelligibility of sentences deemed relevant to the diving environment was also tested. In-water intelligibility testing levels were correlated with accepted in-air standards using measured hearing and speech reception thresholds as common reference points between the two media. Binaural intelligibility tests were performed in a pool using Auditec and Campbell PB50 word lists. Based on averaged results from two underwater listeners, intelligibility for the finished communicator measured 82% correct responses (5-m distance between transmitting and receiving divers). Similar tests for sentence intelligibility yielded near 100% correct responses for the same conditions.
The intelligibility of words, sentences, and continuous discourse using the articulation index
Authors: DePaolis Rory
Published: October 2005

The relation between the intelligibility of speech stimulus with widely varying message redundancy was measured. Using the original articulation index (AI) methodology [N. R. French and J. C. Steinberg, J. Acoust. Soc. Am. 19, 90–119 (1947)], frequency importance functions and transfer functions (AI versus percent correct) were determined for one speaker speaking 616 PB-50 words, 200 meaningful SPIN sentences, and 44 7th-grade reading level continuous discourse, (CD) passages. Thirty subjects were instructed to write down each word and to estimate the percentage of each sentence and CD passage that they heard correctly. The stimulus was degraded with 4 noise and 11 filtered conditions. The results demonstrate a trend toward less significance of high-frequency cues as message redundancy increases. There is also evidence to recommend the use of speech type specific frequency importance functions when calculating the AI.
A probability model for distributions of speech intelligibility data
Authors: Smith Caldwell P.
Published: October 2005

It was determined that the compound Poisson probability distribution as described by William Feller in An Introduction to Probability Theory and Its Applications, 2nd ed. [(Wiley, New York, 1975), pp. 270–273] is a valid model for distributions of speech intelligibility scores from diagnostic rhyme tests. This was established from details of scores from 110 multispeaker tests of a variety of speech processing conditions. Probability models were constructed by first converting feature scores to integers representing frequencies of errors in listener responses, and calculating means and variances of those distributions. Variance of a compound Poisson distribution is equal to the mean divided by p, and in this corpus of data the value of p tended to remain relatively fixed at an average value of 0.129, with the consequence that distributions were essentially defined by mean values and dispersions a linear function of means. In these measures, variance averaged 7.75 times the mean, with the average value of this coefficient varying over a limited range with different speech processing conditions: for LPC processors, the average was 8.37; for wideband processors, 7.12; for processors in tandem, 6.75; and for speech in Gaussian noise, 8.06. Partitioned into separate data sets for voiced and unvoiced feature scores, the same trends were observed, but with coefficients approximately 15% larger with voiced data, and approximately 20% smaller with unvoiced data.
The role of lexical status in the segmentation of fluent speech
Authors: Henly Anne S. , Nusbaum Howard C.
Published: October 2005

Theories of word recognition propose that listeners use lexical status to segment one word from another in fluent speech. Thus words must be recognized one at a time, in the order in which they were produced. This leads directly to the following predictions: (1) Words should be easier to identify following a word than following a nonword. (2) The lexical status of a syllable following a word should not affect the identification accuracy of that word. Subjects in the present experiment were asked to identify monosyllabic and trisyllabic target words presented in noise. Target words were presented with preceding word and nonword context syllables, as well as following word and nonword context syllables. Although the results confirm that listeners are able to use lexical status to facilitate segmentation, they also strongly suggest that listeners' use of lexical status is quite unlike the segmentation strategies proposed by most models of word recognition. [Research supported by NIDCD.]
Analysis of hesitations in spontaneous speech
Authors: O'Shaughnessy D.
Published: October 2005

Spontaneous speech differs from read speech in several ways, especially in hesitation phenomena. This paper reports results on hesitation pauses (filled and unfilled) and restarts. For comparison purposes, the acoustic correlates of (unintended) hesitation pauses are compared to those for intentional pauses. A distinction is made between grammatical pauses (at major syntactic boundaries) and ungrammatical ones. Such pause types cannot be separated based on silence or prepausal duration, but rather in the pitch of the prepausal word. Ungrammatical pauses tended to have few F0 continuation rises, whereas virtually all grammatical pauses were accompanied by a prior F0 rise of at least 10 Hz. While silent pauses are easy to locate in speech recognition applications, filled pauses (e.g., “err,” “umm”) resemble words in continuous speech. Filled pauses at major syntactic boundaries were about 300–450 ms, whereas those within syntactic units were shorter. Filled pauses had falling or flat and low F0 patterns. Ones at syntactic boundaries tended to start higher in F0 and then fall, whereas filled pauses internal to a syntactic unit had lower F0 patterns. Concerning restarts in spontaneous speech, when a work was completely repeated, it had virtually the same prosodics in both its instances. When a word was changed in the restart, its second instance was more stressed. [Work supported by Canadian government.]
Propagation theory of extended noise sources: Improvements and new developments
Authors: Rees C. David
Published: October 2005

Both understanding the source generation characteristics of ocean surface noise and other extended sources from the viewpoint of oceanographic acoustics, and achieving a useful understanding of the characteristics of a noise field at a sensor array to discriminate against noise, require accurate modeling of source to sensor propagation. Kuperman and Ingenito [J. Acoust. Soc. Am. 67, 1988–1996 (1980)] laid out a general Greens function technique for the totally range independent vertically stratified case, but treated in detail only a totally uncorrelated infinite sheet source. The author has developed and analyzed extensions to this approach, including specified source correlation functions and extended sources of finite extent. Development of a range-dependent propagation theory seems to be required to achieve the observed noise peak at near-horizontal angles. The parabolic equation formalism provides a natural basis for this: techniques and results developed by the author to date are discussed and presented.
Three-dimensional rough interface scattering of ambient noise
Authors: Liu Jin-Yuan , Schmidt Henrik
Published: October 2005

Based on the previously developed theory of perturbation approach to rough surface scattering [W. A. Kuperman and Henrik Schmidt, J. Acoust. Soc. Am. 86, 1511–1522 (1989)] and a model for the noise field generated by surface random sources in an occean waveguide [W. A. Kuperman and F. Ingenito, J. Acoust. Soc. Am. 67, 1988–1996 (1980)], a formulation for rough interface scattering of surface-generated ambient noise in a horizontally stratified ocean is established. The result is then applied to study the three-dimensional scattering in a shallow-water waveguide environment bounded below by a viscoelastic medium. The three-dimensional spatial correlation of the reverberated noise in the waveguide and the scattered noise in the elastic medium are examined in terms of the relation to frequency, water depth, and rough interface statistics. It is demonstrated that even in deep water, the scattering of surface generated noise into interface waves (Scholte waves) is important, showing these waves carriers of ambient noise energy consistent with experimental observation. [Work supported by NOARL.]
Trends of wind and noise dependency at Lake Pend Oreille, Idaho
Authors: Cummings Jonathan
Published: October 2005

Ambient noise and wind-speed measurements were obtained at Lake Pend Oreille periodically from October 1985 through August 1989. Cyclic trends in noise levels were observed and are summarized. Variations in noise level with time of day and season of the year correlate well with wind speeds and trends in recreational boating use. Daily averaged data show the contribution of recreational boating to lake noise: 10–15 dB average level increase for midday as compared to night. Average seasonal trends are generally higher (up to 10 dB) during the summer months as compared to winter months. Noise dependencies on wind speed were empirically derived and are found to compare well with observations from ocean environments.
The hydrodynamic and acoustic behavior of bubble plumes generated by an impacting water jet
Authors: Kolaini Ali , Roy Ronald A. , Crum Lawrence A.
Published: October 2005

The preliminary results of an experimental study of the underwater sound field emitted by a bubble plume generated by dropping fixed volume of water, held in a cylindrical container, onto a still water surface were previously presented [J. Acoust. Soc. Am. Suppl. 1 88, 514 (1990)]. Further studies of the acoustic and hydrodynamic characteristics of the bubble plume are presented. The high-speed video images reveal the formation of a cylindrical plume that grows in length until all of the impacting water volume is injected into the still water. As the leading end of the plume advances, a “substructure” separates from the rest of the plume. The onset of the large-amplitude, low-frequency sound emission occurs at the instant the substructure detaches. The resonance frequencies of the densely populated substructures are inversely proportional to their radii and are highly dependent on the void fraction. Experimental results are presented which show that detached plumes undergo damped volume oscillations. The measured damping coefficients are found to be constant and are believed to be related to the thermal damping coefficient. The dependence of the detached plume diameters and undetached plume lengths on the containers radii, lengths, and heights above the still water level are also discussed. [Work supported by ONR and ONT.]