bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective adaptation produced by ongoing speech
Authors: Rudnicky A. I. , Cole R. A.
Published: October 2005

In the selective adaptation paradigm, subjects typically hear repetitions of a single syllable (e.g., [pha]) and subsequently identify syllables from a test series spanning two phonetic categories (e.g., [ba] − [pha]). Experiments have shown that the adapting syllable produces a shift in the phoneme boundary of the test series, such that fewer syllables are assigned to the phonetic category of the adapting syllable. In the present experiments we determined that selective adaptation could be observed using ongoing speech. Subjects were first presented with syllables for identification from an acoustic continuum (e.g., [tha] − [da]) in order to determine their phoneme boundary in an unadapted state. Subjects then heard three sentences containing a predominance of a particular phoneme or phonetic feature. For example, a “voiceless stop” sentence might be: “Carl tickled Tillie's toes till Tillie told Carl to quit tickling her toes.” After the third such sentence, subjects were again presented with syllables from the [tha] − [da] series for identification. The sentences produced a significant shift in the boundary of the [tha] − [da] series in the predicted direction. Similar experiments were performed for sentences containing a predominance of affricates or nasals, and similar results have been obtained using prose passages instead of sentences.
Amplitude contingent selective adaptation to speech
Authors: Ganong W. F.
Published: October 2005

A convincing demonstration that a component of selective adaptation to speech is acoustic can be provided by inducing opposite direction boundary shifts on two acoustically different but phonetically identical stimulus continua. This was done by using a contingent adaptation procedure on two continua which differed only in amplitude. The “loud” stimulus continuum, which consisted of nine syllables ranging from /bow/ to /gow/, was synthesized digitally and presented to subjects at 85 dB SPL. The “quiet” continuum was made by attenuating the same syllables to 50 dB. Phoneme boundaries were measured for both continua before and after adaptation with an alternating sequence of loud /gow/'s and quiet /bow/'s. An amplitude contingent boundary shift was obtained. Adaptation shifted the “loud” continuum boundary toward /g/ and the “quiet” continuum boundary toward /b/. Since amplitude is not part of the linguistic description of speech sounds, this amplitude contingent adaptation effect must reflect changes in processing at an acoustical level of analysis.
On the inability to selectively ignore “irrelevant” stimulus parameters
Authors: Shand Michael A. , Smith Timothy S.
Published: October 2005

C. C. Wood and R. S. Day [Percept. Psychophys. 17.4, 346–50] have shown that reaction times (RT) to target segments within a syllable are significantly longer when the unattended segment in the syllable (either stop consonant or vowel) is varied randomly than when it is held constant. This has been taken as evidence for the perceptual unity of a stop-consonant-vowel syllable. However, this conclusion could be accepted with much more confidence if it could be shown that random variation in unattended segments does not cause an increase in RT if the unattended segments are not in the same syllable as the target segment. The present study, using bisyllabic natural speech stimuli, (1) reconfirms Wood and Day's results but (2) finds that random variation in unattended nontautosyllabic segments also results in significantly longer RT's than without nontautosyllabic random variation. These results will be discussed within the context of general models of the speech perception process. [Work supported by NIH.]
Fiber-optic acoustic array
Authors: Shajenko P.
Published: October 2005

A fiber-optic acoustic array utilizing a novel acousto-optic transducer that provides frequency modulation of light by the acoustical pressure wave is presented. The transducer consists of two parallel mirrors forming multireflecting vibrating surfaces between which a laser beam is propagated. Because the frequency of the laser beam is Doppler shifted at each reflection in proportion to the instantaneous velocity of the mirror, high multiplication of the frequency shift is attainable. Hence, the transducer's sensitivity is greatly enhanced. The light beam is guided to and from the transducer by optical fibers. The beat signal is produced by combining the output light beam with a reference light beam, using the heterodyne technique. The very high signal-to-noise ratio inherent in the optical heterodyne technique permits the use of low-loss single-mode optical fibres and low-power lasers. Preliminary experimental data are included. [Work supported by Naval Material Command.]
Acoustic loading effects on a cylindrical line array resulting from an internal concentric compliant tube baffle
Authors: Martin J. E.
Published: October 2005

The performance of a cylindrical line of array of radially, vibrating ceramic rings when liquid filled for pressure compensation is affected by the acoustic loading of the internal cavity. This internal loading may be varied by the use of a concentric baffle of compliant tubes. This paper presents experimental data showing variations in acoustic loading resulting from various sizes and numbers of tubes used in the baffle and an approximate method of calculating these effects.
Calibration of ultrasonic probe transducers
Authors: Brendel Klaus
Published: October 2005

The calibration of ultrasonic probe transducers without a primary standard (reciprocity method) is expediently performed at megahertz frequencies by using a two-transducer technique. The measurements must be performed mainly in the near-field of the transducers (Fresnel zone) and several corrections are necessary. Thus the effects of different diameters of the transducers, of the sound attenuation loss, and of the disturbances of the sound field due to reflections at the transducers to be calibrated must be considered. These corrections are supposed to be one reason for the rather rare use of reciprocity calibrations in the megahertz-frequency range. The two-transducer technique without a primary standard which is used at the Physikalisch-Technische Bundesanstalt (PTB) is briefly described. It is shown that a sufficient measurement accuracy is achieved, if the effects mentioned above are corrected. The uncertainty of the results of the measurements is estimated to be smaller than ±1 dB.
Design of a curved face parametric projector
Authors: Bennett M. B. , Slack C. M.
Published: October 2005

A curved face transducer array was designed, fabricated, and tested. Multiple rectangular beams were desired in which each beam would be broad in the vertical plane and narrow in the horizontal plane. The high electrical input power required to generate parametric rectangular beams on the order of 3° × 30° dictated the use of a large ceramic area design. The curved face design selected provides the ceramic area required along with a low profile housing. A large number of narrow staves were used in order to provide versatility in selection of the vertical beamwidths. Construction difficulties and solutions are described. Each individual stave was bizonally shaded and the selected stave combinations were also shaded. Experimental beam patterns taken in both planes as well as computer predicted patterns are shown. [This work was supported by Naval Sea Systems Command.]
Back lobe level of an experimental PARRAY
Authors: Goldsberry Tommy G. , Olsen Wiley S. , Reeves Charles R.
Published: October 2005

The directional response characteristics of the parametric acoustic receiving array (PARRAY) have been shown analytically to be essentially those of a continuous, end-fired array with a length equal to the pump-hydrophone separation [H. O. Berktay and J. A. Shooter, J. Acoust. Soc. Am. 54, 1056–1061 (1973)]. The analytical model predicts that the levels of successive side lobes decrease monotonically to some minimum in the back direction. A number of earlier studies have established the validity of the analytical expression for the directional response function over the main lobe and first few side lobes; however, measurements of the far-side lobe levels and front-to-back ratio have not been reported. Using an experimental PARRAY with a pump-hydrophone separation of 60 m, measurements of the front-to-back ratio have been obtained for signal frequencies from 250 to 1000 Hz. These measured data are presented and compared to predictions based on the analytical model. [This work was supported by the Defense Advanced Research Projects Agency and the Naval Electronic Systems Command, Code 320.]
Signal processing for parametric acoustic receiving array experiments
Authors: Truchard J. J.
Published: October 2005

In this paper some of the special techniques required for signal processing for parametric acoustic receiving arrays are described. Experiments on the parametric receiving array require signal processing techniques that are unique in the area of underwater acoustical measurements. A theoretical expression for the parametric receiving array sideband signals is developed and described. An experimental arrangement that has been successful and several possible configurations for use in measurements on the parametric receiving array are discussed. Geometrical constraints that minimize the effects of reflections and ensure a steady state, far-field measurement are also discussed.
A near-field model of the parametric radiator
Authors: Mellen R. H.
Published: October 2005

A near-field model of the Westervelt parametric radiator is presented based on three asymptotic solutions, i.e., the beam pattern for an exponentially tapered line array and the axial levels for a cylindrical or conical source depending on whether the observation distance is less or greater than the Rayleigh distance. The model exhibits changes in beam pattern and apparent source level as the Westervelt limit at large distance is approached. The results are compared with experiment and greatest errors found near the Rayleigh distance are of the order of 3 dB. [Work supported by NAVSEA.]
Parametric receiver with nonlinear interaction in a silicone rubber waveguide
Authors: Corsaro R. D.
Published: October 2005

This paper examines the effects of placing a silicone rubber cylinder between the pump and receiving hydrophone in a parametric receiver configuration. The use of this rubber cylinder is found to considerably reduce the required pump-receiving-hydrophone separation distance, as compared with that required for comparable beamwidths in a water medium alone. This improvement in directivity is related to the low sound speed in silicone rubber (∼1000 m/s), which allows the rubber cylinder to act as a slow acoustic waveguide antenna. At the same time, the parametric conversion efficiency of the array is significantly increased, due to both, the low sound speed and high nonlinearity parameter (B/A∼8) of this rubber. These observations are consistent with those of a previous study [J. D. Ryder, P. H. Rogers, and J. Jarzynski, J. Acoust. Soc. Am. 56, S42(A) (1964), and in press], where the same rubber cylinder was used in a parametric transmitter configuration.
The acoustic reflex in relation to continuous vs brief tone stimuli
Authors: Weatherby L. A. , Shallop J. K. , Blake P. A.
Published: October 2005

Continuous and various brief tone (10 to 1000 msec) stimuli were used to elicit the acoustic reflex (AR) in normal hearing subjects. Approximately 44% of the subjects did not exhibit an AR at the shorter durations of 10 and 20 msec. Subjects were separated into two groups: those who exhibited an AR at all stimulus durations and those who did not exhibit an AR at the shorter durations. AR threshold means were determined for each group at each duration. The group not exhibiting an AR at all durations was characterized by a steeper slope of temporal integration and higher continuous tone thresholds than the group exhibiting an AR at all durations.
Temporal masking patterns for hearing-impaired and normal listeners
Authors: Cudahy Edward A. , Elliott Lois L.
Published: October 2005

Forward masking, backward masking, and gap masking were employed to investigate temporal processing by hearing-impaired and normal listeners. Masked thresholds for a 5-reset 2500-Hz tonal signal in the presence of a narrow-band (1175–1725 Hz) noise masker were measured with a 21FC procedure. (This study represents an extension of previous work in a lower frequency region.) In the gap masking conditions, the noise was on continuously except for a brief silence, or “gap,” of 200-, 50-, or 20 msec. In general, hearing-impaired listeners had less steep backward masking functions than did the normal Ss. They also showed less decrease in masking during the gap. As the duration of the gap decreased, the difference in the gap masking patterns between normal and hearing-impaired Ss increased. The implications of these results for temporal processing by hearing-impaired listeners will be discussed.
Cochlear frequency sharpening—a new model
Authors: Manley Geoffrey A.
Published: October 2005

The basilar membrane is not sufficiently sharply tuned to account for the frequency selectivity of sensitive eighth-nerve fibers [E. F. Evans in Facts and models in hearing, edited by E. Zwicher and E. Terhardt (Springer, NY, 1974), pp. 118–129]. Anatomical evidence indicates no obvious pathways which could mediate classical lateral inhibition and physiological data indicate no time delays in the establishment of the selectivity of eighth-nerve fibers. Any proposed “second filter” must be physiologically vulnerable and be interposed between the basilar membrane response and nerve fiber output. The model proposed here assumes that the uniformity of threshold and response properties of spiral ganglion units [D. Robertson and G. A. Manley, J. Comp. Physiol. 91, 363–375 (1974)] indicates all or almost all recordings originate from inner hair cell afferents. A model is proposed of lateral interaction between hair cells via current pathways in scale media. At frequencies other than the characteristic frequency, current is shunted away from the velocity sensitive inner hair cells of the characteristic frequency location by all active outer hair cells. The model predicts sharp tuning curves with “tails,” two-tone inhibition, the effects on units of electrical polarization of the cochlea, the pattern of inhibition produced by stimulation of the crossed olivocochlear bundle, and is compatible with evidence for longitudinal interactions [A. Ryan and P. Dallos, J. Acoust. Soc. Am. 57, S41 (1975)].
Finite-amplitude saturation of plane sound waves in air
Authors: Webster D. A. , Blackstock D. T.
Published: October 2005

When the received level of a transmitted acoustic wave reaches an upper limit that cannot be exceeded regardless of how much acoustic power is radiated by the source, the wave is said to have saturated. Experiments on saturation of plane waves in air are reported in this paper. The measured quantity is the pressure amplitude P1 of the fundamental. To obtain a theoretical prediction valid close to and including saturation, we assume the decay rate of P1 is the sum of the sawtooth and ordinary absorption decay rates (Rudnick's assumption). Solution of the assumed equation gives P1 = 2p10e−αx/[1 + (1−e−αx)/αx̄] where p10 is the source amplitude, α is the ordinary (small-signal) attenuation coefficient, and x̄ is the shock formation distance. The experiments were done in a plane-wave tube over a frequency range of 2–4 kHz at source levels up to 160 dB (re 0.0002 μbar). The data confirm the theoretical prediction. Design curves to assess the importance of nonlinear propagation effects on spherical waves in the atmosphere are also given.
Propagation distortion of finite-amplitude acoustic fields
Authors: Clark J. A.
Published: October 2005

Propagation characteristics of large amplitude (8–10 atm), initially sinusoidal, water-borne acoustic waves are experimentally investigated by a whole-field optical measurement method. The method used a schlieren optical system with a slit-type spatial filter. Images of the sound field were obtained which exhibited families of fringes corresponding to contours of constant acoustic pressure gradient. Sequences of these images were used to determine the propagation velocity of nulls, peaks, and valleys in the spatial acoustic pressure waveform. Amplitude-dependent variations in the local wave velocity were detected. The signs and magnitudes of the variations were in agreement with predictions of approximate theories of finite-amplitude wave propagation. The results demonstrate the feasibility of applying this optical measurement method to studies of finite-amplitude waves under conditions where theoretical methods fail.
Theoretical study of the acoustic impedance of orifices in the presence of a steady grazing flow
Authors: Rice E. J.
Published: October 2005

An analysis of the oscillatory fluid flow in the vicinity of a circular orifice with a steady grazing flow is presented. The study is similar to that of Hersh and Rogers but with the addition of the grazing flow. Starting from the Navier-Stokes and continuity equations, a considerably simplified system of partial differential equations is developed with the assumption that the flow can be described by an oscillatory motion superimposed upon the known steady flow. The equations are seen to be linear in the region where the grazing flow effects are dominant, and a solution and the resulting orifice impedance are presented for these equations. Some preliminary conclusions of the study are that orifice resistance is directly proportional to grazing flow velocity (known previously from experimental data) and that the orifice inductive (mass reactance) end correction is not a function of grazing flow. This latter conclusion is contrary to the widely held notion that grazing flow removes the effect of the orifice inductive end correction. This conclusion also implies that the experimentally observed total inductance reduction with grazing flow might be in the slug flow within the orifice rather than in the end correction.
Some observations regarding ultrasonics-assisted vacuum filtration
Authors: Otsuka T. , Fairbanks H. V.
Published: October 2005

The purpose of this investigation was to explore the possibility of using ultrasonics to produce a drier filter cake in vacuum filtration. The research was divided in two phases: (1) use of airborne ultrasonics near the filter cake surface and (2) use of ultrasonics to vibrate the filtration membrane. The ultrasonics frequency of 20 kHz was used with intensities varying from 0 to 12 W cm2. The filter thicknesses used varied from 2 to 5 mm, the vacuum applied varied from 260 to 510 mm Hg. The airborne ultrasonics was applied at distance of 1/4 to 13/4 wavelength which were equivalent to 4–52 mm away from the filter cake surface. Filtration time was varied from 1 to 5 min. From the data obtained, the effect of ultrasonics on dryness of the filter cakes, was calculated using the various conditions described above. It was found that ultrasonics could be effective in reducing the moisture content of cakes produced by vacuum filtration.
Influence of ultrasonic vibrations during corrosion of metals
Authors: Fairbanks H. V.
Published: October 2005

The purpose of this investigation was to make an exploratory study of the effect the introduction of ultrasonic vibrations might have upon the corrosion of metals. Both dry and wet corrosion were studied. The ultrasonic frequency of vibrations used was 20 kHz with power levels up to 30 W/cm2 being introduced into the metals, and power levels up to 0.3 W/cm2 being introduced into the electrolytes. In dry corrosion, at elevated temperature, the introduction of ultrasonic vibrations produced a more dense corrosion film on the surface of the metal. In wet corrosion, it was found that ultrasonic vibrations generally increased the rate of corrosion and attempted to negate cathodic protection of the metal. Potentiostat experiments showed that the introduction of ultrasound substantially increased the flow of current in the system.
Function and tonal quality of string instruments
Authors: Jansson E. V.
Published: October 2005

The function of the violin and the guitar are being investigated. Plate vibrations are recorded by hologram interferometry in cooperation with the Institute of Optical Research, KTH, and a qualitative understanding of eigenmodes and their excitation have been obtained. Properties of the enclosed air volume have been investigated by means of the STL-Ionophone, which has proved that higher air volume resonances can be used as sound radiators. Played scales recorded in reverberation chamber are analyzed by long-time-average-spectra (LTAS). Such analysis has proved that different instruments may be separated by LTAS. Work is in progress trying to correlate LTAS with function and tonal qualities. Listening tests have been started in cooperation with A. Gabrielsson (Department of Psychology, University of Uppsala). Findings from the present investigations will be reported on. [Work supported by the Swedish Natural Science Research Council and the Swedish Humanistic Research Council.]
Plates and resonance boards
Authors: Skudrzyk Eugen
Published: October 2005

A resonance board should vibrate evenly in a wide frequency range and should generate a sound pressure that does not vary greatly with frequency. Recent results obtained in the theory of plate vibrations make it possible to predict the frequency response of plates, the heights of the resonance maxima and the depths of the minima, in terms of simple parameters such as the mass per unit area, the density of the resonances along the frequency scale, and the loss factor of the material. It is thus possible to prescribe the amplitude differences permitted between the vibration maxima and the minima in the frequency response of a resonance board. The corresponding theory for the sound radiation is being developed using acoustic holography to record and measure the sound generation of the various parts of the vibrator. The basic results will be presented.
Review of the practical aspects of material damping measurements
Authors: Henderson J. P.
Published: October 2005

The rational design of structures incorporating damping materials for the control of vibration and noise requires a knowledge of the dynamic properties of vibration damping materials, including the effects of frequency, temperature, and strain levels. This paper is a review of several techniques which have been utilized for determining material damping properties, with special emphasis on the practical limitations of each method. It is pointed out that no one measurement technique is universally applicable to all damping materials since they range in stiffness from very soft foams and adhesives to relatively stiff unconstrained layers such as damping tiles and vitreous enamels. Furthermore, damping measurements are frequently required at temperatures ranging from −60° to + 1000°C (−76° to + 1832°F). The applicability of various measurement techniques to different classes of materials is discussed, along with pitfalls commonly encountered due to the magnification of errors in the reduction of data.
Measurement of vibration damping materials
Authors: Rasmussen Gunnar
Published: October 2005

Vibration damping materials play an increasing role in environmental protection and mechanical design. Specially developed resins with optimized properties for noise abatement applications are used with success. As most metals have low internal losses, large amplitudes may be obtained in resonance modes when they are vibrated. The application of coatings of damping material with large internal damping in single layer or sandwich constructions has proved very effective in “deadening” noisy structures. A direct consequence of these developments is a great need for an objective damping measuring technique. The intersting viscoelastic properties are the density and the complex modulus of elasticity of the materials Ē = E′ + jE″ (j =−1) and the complex shear modulus Ḡ = G′ + jG″. As Ē and Ḡ are closely related through the Poisson ratio, the measurement of the complex modulus of elasticity will do. The real part E′ represents the dynamic stiffness which is the storage modulus representing the energy stored in the material during oscillation, the normally used term is dynamic modulus of elasticity. The imaginary part E″ is a measure of the loss modulus representing the energy losses. The loss factor is d = E″/E′. The viscoelastic properties may be measured through an experimental setup using standardized samples mounted in a well defined fashion and brought into oscillatory motion. The dependency on temperature and frequency may be determined in this experimental setup which is standardized in DIN 53440, pp. 1–3. Considerable experience with this method has been gained over twenty years. The method was pioneered by the late Dr. Hermann Oberst.
Decay of auditory sensation: A model and new results from a reaction-time experiment
Authors: Rosen Stuart Michael
Published: October 2005

Plomp [J. Acoust. Soc. Am. 36, 277–282 (1964)], in explaining results on the detection of gaps in noise bursts, suggested that auditory sensation decays as a power function of time. According to Plomp's interpretation, the sensations resulting from more intense stimuli have faster rates of decay than sensations resulting from less intense stimuli, in such a way that all sensations reach threshold at the same moment after stimulus offset, independent of intensity. This suggestion is made quantitative and the resulting model is applied to Homp's data and to new data exploring the effects of intensity on reaction time to offsets of noise bursts. [Work supported by NSF and NIH.]
Ear differences in reaction time to onsets and offsets of monaurally presented signals
Authors: Emmerich D. S. , Pitchford L. J.
Published: October 2005

Previous research has shown that subjects can respond to the onsets of sinusoidal signals more rapidly than to the offsets of such signals. The difference in the speed of response to onsets and offsets of monaurally presented signals was investigated for three different signal frequencies: 500, 1000, and 4000 Hz. For the two higher signal frequencies it was found that this difference in reaction time to onsets and offsets was greater for signals presented to the right ear than for signals presented to the left eat. This eat difference resulted mainly from slower responses to the offsets of signals presented to the right ear than to the offsets of signals presented to the left ear. This ear difference is unusual in that it was obtained with monaural presentations of simple stimuli: the ear differences most frequently reported are typically found with dichotic presentations of complex (speech) stimuli. Previously reported ear differences have been attributed to differences in hemispheric organization of the brain. The basis of the present results is unclear.
Origin of the notch in two-tone masking
Authors: Nelson D. A. , Bilger R. C.
Published: October 2005

Two-tone masking of a 1000-Hz narrow-band noise by high-level masking tones (60–100 dB SPL) yielded notches in the resulting two-tone masking functions. As orginally demonstrated by Zwicker [Acustica 4, 415–420 (1954)], those notches occurred at large frequency separations between masking tones. In a search for an adequate explanation of those notches, reversed masking functions were obtained for the 1000-Hz narrow-hand noise masked by constant-intensity single-tone maskers at frequencies above the 1000-Hz narrow-band noise and at frequencies below the 1000-Hz narrow-band noise. In further experiments, selective off-frequency masking was employed at frequency regions of suspected distortion components. The results indicated (1) that the notch obtained in two-tone masking functions is due primarily to the lower-frequency tone of the two-tone masking complex; (2) that the frequency separation at which the notch occurs is dependent upon the level of the masking tones; and (3) that the notch can be eliminated with selective off-frequency masking. Alternative explanations for the notch are discussed which include the detection of off-frequency distortion components and/or limitations in the temporal resolving power of the auditory system. [Work supported in part by NIH grants NS-10561, NS-12125, and NS-04105].
Further observations on the role of silence as a cue for stop consonants
Authors: Dorman M. F. , Raphael L. J. , Liberman A. M.
Published: October 2005

Previous research has shown that silence is a necessary condition for the perception of stop consonants in such utterances as /sa/ vs /sta/. In cases of that kind, there are cues in the vocalic portion of the syllable that are appropriate for stop-consonant manner. Hence, the silence has not been shown to be a sufficient cue for stop manner. In the present series of experiments we have investigated the role of silence in the perception of stops when there are no stop-manner cues in the vocalic portion. The purpose is to determine the extent to which the silence cue can be not only a necessary but sufficient cue for stop consonants.
Effect of speech fragments on the perception of a phonetically ambiguous word
Authors: Swift D. J. , Limber J.
Published: October 2005

An ambiguous word (s*ore) interpretable as store or score was created by excising all remnants of the [t] from store and replacing it by 150 msec of silence. Parameters controlling the perception of this form were systematically investigated as follows. [t]-fragments or [k]-fragments excised from store or score were presented concurrently (or delayed 100 msec) with the silent interval of s*ore. Two fragment durations, 80 and 150 msec, were used. All fragments were presented dichotically and monotically. S*ore itself and s*ore with a 150-msec tone served as controls. Subjects pressed a button when they perceived a designated target word, store or score, within a list including controls and fillers. Stimuli were prepared using the PDP-9 computer facility at MIT. Across all conditions fragments controlled the perception of s*ore in the appropriate direction over controls (p < 0.0001). The strongest effects were in the simultaneous and monotic conditions, but dichotic and delay conditions were significant (p < 0.001). Implications of these results for explanations in terms of acoustic adding, high-level blending, and biasing are considered.
Temporal interaction in speech perception
Authors: Carlson R. , Granström B.
Published: October 2005

In perception of speech the listener tends to focus on certain aspects while others are neglected. This priority process could partly be disturbed by distortions of different kinds but is in general based on the listener's knowledge of the language in question. Descriptive models of temporal interactions mostly don't take into account the perceptual importance of observed or predicted regularities. This paper is concerned with the question of how perception of segmental duration reveals temporal interaction on syllable, word, and phrase levels. One of the techniques used was a production experiment with synthetic speech. In this experiment the task was to interactively manipulate a segment duration in a sentence while the duration of another segment was randomized. Both positive and negative correlations were found.
Voice onset time of spontaneously spoken Spanish voiceless stops
Authors: Dent Laurel
Published: October 2005

Spectrographic measurements were made of voice onset time for 161 tokens of Spanish voiceless stops from one individual's conversational speech in an attempt to replicate laboratory findings on VOT. In running Spanish, occlusive allophones of voiced-stop phohemes occur only in absolute initial position and after nasal consonants. In other environments, voiced-stop phonemes are phonetically voiced fricatives. Therefore the contrast between voiced- and voiceless-stop phoneme categories is maintained not only by the presence or absence of voicing, but also by the presence of frication (voiced phonemes) or its absence (i.e., closure for voiceless phonemes). Due to the limited distribution of voiced-stop allophones, these are scarcely represented in the present sample, and their VOT values are not reported. In spite of VOT's “reduced” work load, however, the VOT values for voiceless stops in this study conform quite closely to earlier observations of production and perception of Spanish stop phonemes. VOT values for voiceless stops in utterance-initial and post-nasal positions are not significantly different from those for stops in other positions.
Properties of feature detectors for VOT
Authors: Miller J. L.
Published: October 2005

Certain properties of a feature detector system sensitive to VOT were investigated with a binaural adaptation-dichotic testing paradigm. On each dichotic test trial, a nonboundary voiced stop was paired with one of a set of voiceless stops. The voiceless stops varied in VOT, from values close to the phonetic boundary to values well within the voiceless category. The relative effectiveness of each of the voiceless stimuli in competing for processing with the voiced stimulus was assessed before adaptation and after adaptation with voiceless stops with a range of VOT values. During both pre- and postadaptation, the number of correct voicing responses when targeting for the voiceless stop, and the number of voicing intrusions when targeting for the voiced stop, systematically varied as a function of the VOT value of the voiceless stimulus. In addition, the VOT value of the adapting stimulus determined the amount of adaptation obtained. These results indicate first, that the output of the detector is a graded signal, and second, that the magnitude of decrease in detector sensitivity during adaptation is a function of the VOT value of the adapting stimulus. [Supported by NIH grants.]
Study of the effect of propagation loss variability on sonar performance prediction
Authors: Lauer R. B. , Browning D. G. , Skory J. , Botseas G. , DiNapoli F. R.
Published: October 2005

It is known that sound propagation in the ocean can be highly variable with time; however, it has not been determined if this variability is significant under typical sonar propagation conditions. To answer this question, a controlled experiment was conducted in the Tongue of the Ocean, Bahama Islands. A shallow source was suspended at various ranges from a fixed hydrophone array and a time series of transmission loss measurements obtained. A computer program (designated STAMP—Statistics of Acoustic Measurements and Prediction) was utilized to analyze these reults. Statistics are compared for both peak and energy propagation loss analysis. A comparison of the variability of direct path and bottom reflected arrivals is also made. [Work supported by NUSC.]
A quantitative relationship between geometry reconstruction inaccuracies and errors in the SPL correction for the Lloyd's mirror effect
Authors: O'Connor James C. P.
Published: October 2005

In attempting to calculate the spectral sound pressure level of an acoustic signal from measurements made in an underwater environment subject to surface interference effects, spectral amplitude correction techniques must be used. One such technique is based on the reconstructed source-receiver geometry. For the static situation in which the geometrical parameters are accurately known, a reliable correction can be made. For the dynamic case, however, in which there is a relative motion between the source and receiver, inaccuracies are likely to exist in determining the pertinent geometrical parameters such as source and/or receiver depths, source-receiver range, relative velocity, and sound speed. These inaccuracies translate directly into errors in the calculated sound pressure spectrum levels. The present analytical study quantitatively relates errors in determining the geometrical parameters to errors in the resulting Lloyd mirror corrections for the situation involving relative motion between the source and receiver. [Work sponsored by Naval Air Systems Command.]
Amplitude and phase fluctuation periods for long-range ocean propagation
Authors: Dyer I.
Published: October 2005

It is commonly observed in long-range propagation that the phase fluctuation period is longer than the amplitude fluctuation period. A phase-random multipath model used previously to explain amplitude statistics [I. Dyer, I. Acoust. Soc. Am. 48, 337–345 (1970)], is now applied to the joint problem of amplitude and phase. The ratio of phase period to amplitude period is found to be (8π)1/2 P(ρ0), where P(ρ0) is the probability density for ρ=ρ0, ρ is the amplitude, and ρ0 is a level used to define the period via the crossings. P(ρ0) is Rayleigh. Thus the phase period is about four times the amplitude period, for choices of ρ0 between the rms and the most probable values of the amplitude. This result appears to be consistent with experience. Note that no specific dynamical process, such as internal wave motion, need be invoked explicitly to obtain this result. [Supported by ONR.]
Low-frequency sound attentuation in the Northeastern Pacific Ocean
Authors: Morris G. B.
Published: October 2005

Signals from SUS bombs were received at four hydrophones suspended in the deep ocean from the Research Platform FLIP. Using digital processing equipment and fast Fourier transform methods, energy-flux spectral densities were determined for approximately 700 shots out to a maximum range of 1600 nautical miles. Differences in propagation losses at various octave and one-third-octave frequency bands up to 400 Hz were used to calculate attenuation values. The resulting values are lower than those predicted from Thorp's equation, but are in agreement with published values determined from cw acoustic transmission experiments in the Northeastern Pacific [J. R. Lovett, J. Acoust. Soc. Am. 58, 620–625 (1975)]. [Work supported by the Office of Naval Research.]
Model for the radiated noise source spectra of merchant ships
Authors: Heine J. C. , Gray L. M.
Published: October 2005

Ocean ambient noise in the frequency range 20–300 Hz is, in many cases, dominated by the radiated noise from merchant ships [G. M. Wenz, J. Acoust. Soc. Am. 34, 1936 (1962)]. Predictions of noise in this frequency regime have usually been based on a ship spectrum of a highly simplified type. A study of the sources of merchant ship radiated noise leads to the conclusions that (1) the radiated spectrum of a typical merchant ship includes two cavitation related sources—continuous and narrow band; (2) the lowest frequency noise attributed to distant shipping is the sum of narrow-band components; and (3) the higher frequency noise is due to the sum of continuous components. In this paper, expressions relating the source spectrum of each component to ship engineering parameters (e.g., propeller diameter) are presented. The shape of the ambient noise spectrum is determined by evaluating these expressions for the distributions of engineering parameters appropriate to the ensemble of ships in the world's merchant fleet. This shape is shown to be characteristic of observed deep-ocean ambient noise.
A class of models for fluctuating acoustic processes
Authors: Moll M.
Published: October 2005

Acoustic processes such as ambient noise exhibit large variations of intensity; usually these variations are much greater than would be experienced with stationary gaussian processes. A class of stationary stochastic process models is discussed which are locally gaussian. The degree of fluctuation can be selected, and the autocovariance functions for the process and its long-term power fluctuations can be specified arbitrarily. These models can be employed for predicting sonar performance in fluctuating environments. [Work supported by ONR.]
Anechoic flow facility at David W. Taylor Naval Ship Research and Development Center: Acoustical features of a facility for flow noise research
Authors: Brown R. William
Published: October 2005

The Anechoic Flow Facility at the David W. Taylor Naval Ship Research and Development Center is a facility designed specifically for flow-noise research. The design objectives were low self-noise of operation and uniform, low-turbulence-flow in the facility test section. The facility features designed to achieve these objectives will be presented and their performance valuated. Necessary compromises in design made between the two objectives will also be discussed. Insights to further improvements in facility design gained from several years of use will be presented.
Effect of small-scale surface roughness on turbulent boundary-layer wall-pressure spectra
Authors: DeMetz F. C. , Casarella M. J. , O'Keefe E. J.
Published: October 2005

An experimental study of the boundary-layer velocity profiles and turbulent wall-pressure spectra on a smooth flat plate with varying localized roughness conditions has been conducted in the Anechoic Flow Facility at the David W. Taylor Naval Ship Research and Development Center. The transition and turbulent flow properties are consistent with published results. New data were obtained with a pinhole microphone on the wall-pressure spectra for sandpper surface roughnesses which varied from the hydraulically smooth to hydraulically rough condition. Formulas are presented for estimating the change in wall spectra levels due to the varying surface roughness conditions.
Peripheral origin of auditory responses in the monitor lizard
Authors: Manley G. A.
Published: October 2005

Previous study of cochlear nucleus units in the bengal monitor lizard Varanus bengalensis showed that the responses of these neurons fell into two groups [G. A. Manley, Brain Res. (in press)]. There is a larger group of units with characteristic frequencies (CF) below about 1 kHz and with simple, sharply tuned frequency response curves. The second, smaller group with CF's from 1.1 to 2.8 kHz are less sharply tuned and less sensitive than the lower frequency group. The basilar papilla of this species is divided by a constriction into a ventral region about 0.5 mm long and a dorsal region 1 mm long. By means of a ventral approach through the recessus scala tympani, extracellular recordings can be obtained from afferent nerve fibers leaving the papilla, running along the ventral side of the neural limbus. About two thirds of the ventral papilla and the most ventral third of the dorsal papilla are accessible with this technique. Response properties of fibers isolated from these regions indicate that the ventral papilla is tuned to frequencies corresponding to the small higher frequency population of the cochlear nucleus, and the dorsal papilla is tuned to lower frequencies. On the dorsal papilla, the lowest frequencies are in the most ventral region.
Echo-reception characteristics of single units in the inferior colliculus of awake bats
Authors: Pollak G. D. , Marsh D. S. , Bodenhamer R. , Souther A.
Published: October 2005

Recovery of responsiveness to two-tone pips presented in close temporal sequence was assessed in single units recorded from the inferior colliculus in awake bats (Tadarida brasiliensis mexicana). For each unit the following parameters were varied: (1) the intensity ratio of the simulated pulse-echo pair from a level just below threshold to about 50–60 dB above threshold; (2) the stimulus durations from 8 to 2 msec in 2-msec increments; (3) the above parameters for a number of selected interpulse intervals. Each stimulus combination was designed to mimic the biosonar signals received during natural echolocation. Five types of recovery patterns were observed. Most units, however, exhibited two or more recovery patterns that depended upon stimulus duration. Of the 25 units examined, all but two recovered well with at least one stimulus duration even when the first tone (simulated pulse) was 25–50 dB more intense than the second tone (simulated echo). It is concluded that the majority of collicular units are well suited for responding to pulse-echo combinations at intervals within the range of echo-detection suggested by behavioral studies and at pulse-echo intensities expected to reach the ear during echolocation. [Work supported by NSF Grant P4B1855-000.]
Auditory responses of single neurons in the midbrain of the Tokay Gecko
Authors: Sammaritano-Klein M. R. , Manley G. A.
Published: October 2005

The purpose of this study was to examine the neuronal basis of sound localization in the Gecko Gecko, a reptile that vocalizes for communication, and to provide data for comparison with other vertebrate groups. Using tungsten microelectrodes, response patterns of the midbrain auditory nucleus were studied in 83 cells to contralateral free-field stimulation using pure tones and clicks. Spontaneous rates, tuning curves, intensity functions, and peristimulus-time histograms were analyzed. The peristimulus-time histogram pattern typically showed a sustained response with an early peak. Responses measured to a rotating loudspeaker at contralateral (0°) through 45° intervals to ipsilateral (180°) showed that most cells (75%) had maximum discharges to contralateral (0°) stimulus while smaller populations showed maximum discharges to stimuli at 45°, 90°, and 135°. Latencies increased during rotation from contralateral to ipsilateral and the initial peak of the peristimulus-time histogram diminished. This syncrony of the first spike, also found in the cochlear nucleus [G. A. Manley, Brain Behav. Evol. 10, 244–256 (1974)] suggests a mechanism for sound localization.
Frequency selectivity of single neurons in the Mesencephalicus Lateralis pars Dorsalis (MLD) of the neonatal chick
Authors: Rosowski John J. , Bock Gregory R. , Saunders James C.
Published: October 2005

Chicks were anesthetized with urethane 24–48 h after hatching. A tracheal cannula was inserted and the animal was mounted in a head holder. A probe-tube sound system was sealed against the exposed left tympanic membrane. The right neostriatum was exposed and the posterior region was aspirated to reveal the optic tectum. Glass pipette electrodes with 2–5-μm tips (filled with 3M KCl and a fist green dye) were advanced through the MLD. Each electrode track was marked for histological verification of the electrode location. The frequency selectivity of MLD cells, as shown by tuning curves, was studied in detail. Recordings have been obtained from over 100 cells and the distribution of criticial frequencies, the sharpness of tuning, and response characteristics are discussed. The utility of these data for studies of sensory deprivation or enrichment during the maturation of a precocial auditory system is considered.
Responses of cat auditory cortical neurons to amplitude-modulated noise
Authors: Bock G. R.
Published: October 2005

Swarbrick and Whitfield [J. Physiol. 224, 68–69 (1972)] found a small minority of units in cat primary auditory cortex whose discharge rates appeared to be determined by the symmetry of the stimulus envelope, independent of stimulus duration. This phenomenon was examined in greater detail in the present study. Tungsten microelectrodes were used to record from primary cortical cells in unanesthetized cats. Noise bursts of 4-, 40-, 100-, and 300-msec duration were used, and the rise-time/fall-time ratio was systematically varied for each burst duration. Discharge rates of a few units appeared to preserve information about stimulus envelope, in that the preferred rise-time/fall-time ratio was constant with 40- and 100-msec noise bursts. However, contrary to the observations of Swarbrick and Whitfield, this constancy did not extend to 4-msec bursts. Preferential responses to stimulus shape, when they occurred, were relatively independent of stimulus repetition rate. [Work supported by the Nuffield Foundation.]