bluuebunny/crossref_metadata_2025 huggingface dataset:
“Fox-box illusion”: Simultaneous presentation of conflicting auditory and visual CV's
Authors: Yonovitz A. , Lozar J. T. , Thompson Carl , Ferrell Dianne R. , Ross Mark
Published: October 2005

Eight CV's (with a) were audio/video color recorded. The consonants included p, b, k, g, s, z, f, and v. Using video-editing techniques the audio from these consonants was dubbed such that all possible pairings of each visual consonant occurred with each audio consonant. Thus 64 stimuli were constructed that consisted of 56 conflicting visual and auditory stimuli and eight nonconflicting stimuli. Subjects were seated in front of a video monitor with earphones and asked to write their response to each stimulus item. The auditory-alone mode confirmed unequivocally correct intelligibility of each consonant. However, when conflicting visual speech reading cues were present confusions were reliable and consistent. Confusions within the fricative class (f, v, s, and z) occurred as well as confusions within the stop class (p, b, k, and g). Interclass confusions were also prominent. Especially noteworthy was the perception of consonants not present acoustically (e.g., θ, Ø, t, 1). An extremely robust confusion occurred for (f) presented visually and (b) auditorily. With voicing present auditorily subjects responses were consistently a voiceless (f). These data will be discussed with respect to distinctive feature theory and information processing.
Single hydrophone technique for obtaining spectral source levels of marine mammals in coastal waters
Authors: Bostian L. C. D. R. R. , Medwin H.
Published: October 2005

During the Gray Whale migration from the Aleutians to Baja California the mammal travels in coastal waters, thereby presenting an opportunity for the study of its sound spectral source levels. Using the theory of rough surface scattering, the knowledge of the bottom impedance, and correlation techniques, it should be possible to decompose the shallow water reverberation into the contributions from different paths. From this, the range, the depth, and the spectral source levels of the sounds of the mammal can be determined by use of only one hydrophone rather than the conventional three or four. Results are presented of an experimental study in the NPS Ocean Acoustic Wave Facility using models of the whale's pulsed radiation and of the coastal environment. [Work supported by ONR.]
Towards a consistent acoustical design methodology for concert halls and recording studios
Authors: Walsh John P.
Published: October 2005

In the acoustical design of environments for musical performance, reverberation time specification has served as a useful abstraction of the anticipated behavior of the sound field in the hall. However, recent trends in recording studio design point to the need to isolate two aspects of this abstraction: the diffusion of directional components in the radiation patterns of musical instruments and the imposition of a decay envelope upon delayed components of the sound. An examination of near-field and reverberant field spectral characteristics of a number of musical instruments indicates that the highly directional components associated with many of these instruments will frequently preclude any assumption of the existence of a diffuse sound field within a concert hall. Therefore special attention must be paid to diffusing these components, preferably within the first few reflections. The distinction between directional component diffusion and decay envelope allows the modelling of room performance in a hierarchical manner, and should permit the adoption of a consistent design methodology for both concert halls and studios.
Reflection of sound waves from a rotating diffuser
Authors: Roy K. P. , Tichy J.
Published: October 2005

The reflection of sound waves from a rotating diffuser was studied in both anechoic and reverberant environments. A simple mathematical model was developed for the rotating diffuser in the free field based upon its similarities with the oscillating plane reflector. It is found that due to the Doppler effect the reflected wave is modulated. The model developed allows the determination of both the sideband frequency spacing and the relative sideband amplitudes. The modulated signal spectra depend on the speed of rotation, diffuser size and configuration, the source frequency and the diffuser scattering function. In the reverberant environment the reflections from the diffuser are very complex. The effect on the modulation of modal frequencies of the lowest modes was studied and qualitative conclusions on the diffuser effect were made.
Reverberation time, absorption, and impedance
Authors: Dowell Earl H.
Published: October 2005

A rigorous theoretical model is derived and used to calculate reverberation time of a room in terms of impedance of absorption materials on the wall and geometrical factors associated with such materials and the room. In addition the reverberation time also depends upon the initial state of the pressure field before decay begins as well as the single measure of pressure, for example spatial root-mean-square, used to characterize the decay time history. The theoretical model, which consists of a system of harmonic oscillators with damping provided through the wall impedance, is sufficiently general to take into account all of these factors. A numerical example is given to illustrate the procedure. A brief review of current methods for calculation of reverberation time is given including a discussion of random and normal absorption coefficients. It is shown how these two quantities can be related by the present theoretical model. Current practice is to use an empirical relationship between them.
Acoustic waves and wave action in moving time-dependent media
Authors: Pierce Allan D.
Published: October 2005

The previous results of Blokhintzev and of Bretherton and Garrett [Proc R. Soc. (1968)] concerning wave action conservation in slowly varying moving inhomogeneous fluids are shown to also apply when the ambient state is time dependent. Also, a simple consistent set of approximate fluid dynamic equations is derived which implicitly contains all geometrical acoustics theory but which also governs diffraction phenomena (e.g., caustics). Möhring's [AIAA paper (1977)] energy conservation explanation of S. Davis's (J. Acoust. Soc. Am. 59, 264–266 (1976) reciprocity theorem is reinterpreted in terms of wave action. If an acoustic wave is transmitted through a narrow tube with variable cross-section transition carrying an inhomogeneous flow, the sum, wave action transmitted plus reflected, is equal to wave action incident. The fractions reflected and transmitted are independent of direction of incoming wave.
Layered media model for ground absorption
Authors: Carlson D. E. , McDaniel O. H. , Reethof G.
Published: October 2005

Experiments were conducted for a comparison of a homogeneous model for typical ground surfaces to that of a layered model in actual measured situations. Some 50 different normal incidence ground surface acoustical impedance measurements were made throughout central Pennsylvania. The measured impedance values typically approached that of the characteristic impedance of air in magnitude. Furthermore, positive values for the imaginary portions of the impedance were commonly measured. An assumption of the ground being homogeneous for the above data results in calculated sound speeds of very low magnitudes and the acoustical energy being amplified instead of damped for propagation in the ground. Neither result can be supported on physical arguments. To investigate the possibility of a layered model, typical values of the characteristic impedance of the upper soil layers were introduced into a layered mathematical model in order to predict the normal incidence surface impedance. These calculated results yield the same anomalous results obtained in actual field measurements, indicating that a layered model might be a more accurate representation of the ground. [Work supported by USDA Forest Service and FHWA.]
Vibrational relaxation effects on the propagation of weak shock waves in the atmosphere
Authors: Raspet R. , Bass H. E.
Published: October 2005

The propagation of weak shock waves through the atmosphere has been modeled by a calculation incorporating finite amplitude effects, classical acoustic attenuation, and attenuation due to vibrational relaxation of nitrogen and oxygen. This calculation has been used to study the effect of varying atmospheric conditions on the overpressure decay, rise times, and spectral composition of weak shock waves. The necessity of including vibrational relaxation processes in calculations of shock wave parameters is demonstrated. [Work supported by Office of Naval Research, Atmospheric Sciences Division.]
Diffraction of sound by trapezoidal barriers with distinct surface acoustic impedances
Authors: Hadden W. James
Published: October 2005

A method is presented for predicting the diffracted pressure in the shadow of a trapezoidal barrier whose surfaces are characterized by distinct acoustic impedances. The technique involves superposing solutions of the problem of diffraction of spherical waves by a wedge-shaped barrier using an appropriate matching principle. Several numerical examples illustrate the application of this analysis in predicting the insertion loss for a trapezoidal barrier. For surfaces which are acoustically nearly rigid, increases in insertion loss vis á vis a rigid barrier of approximately 8 dB are predicted. Other examples for softer surfaces are presented. The extension of this analysis to diffraction by a barrier on the ground will be discussed. [Work supported in part by NASA Langley Research Center.]
Analyses of effects of temperature inversions on blast levels within 15 km of Army weapons
Authors: Luz G. A. , Lewis N. D. , Cloutier T. C.
Published: October 2005

Increases of weapons blast noise may be the result of (a) wind or (b) temperature inversions. Only the latter is discussed in this paper. Drawing on a dozen examples observed during environmental noise assessments at four Army posts, the authors suggest that (1) inversion-related increases rarely occur at distances closer than 1 km, (2) increases at locations between 1.5 and 15 km can be as high as 20 dB, (3) the rate of change between 1.5 and 15 km can vary between 10 dB/h and 1 dB/min, and (4) increases are often followed by decreases to below expected levels. The discussion covers the implications of these findings for the alleviation of citizen complaints about Army weapons firing.
Temporal variation of tonal spectrum of tambura
Authors: Janakiram V. L. , Yegnarayana B.
Published: October 2005

Tambura is an essential drone accompaniment used in Indian music concerts. It acts as an immediate reference of pitch for both the artists and listeners. The four strings of Tambura are tuned to the frequency ratio 34:1:1:12. Careful listening to Tambura sound reveals that the tonal spectrum is not stationary but is time varying. The object of this study is to make a detailed spectrum analysis to find out the nature of temporal variation of the tonal spectrum of Tambura sound. Results of the analysis are correlated with perceptual evaluation conducted in a controlled acoustic environment. A significant result of this study is to demonstrate the presence of several notes which are normally not noticed even by a professional artist. The effect of bridge in Tambura in producing the so called “live tone” is explained through time and frequency parameters of Tambura sounds.
Observations on modified tunings in fixed pitch instruments as indications of psychological adjustments to temperament
Authors: Mulder George W.
Published: October 2005

The relative temperament of three different scales was used in tuning fixed pitch instruments. The listener perceiving the temperament within the framework of certain scales accepted the tuning as normal. However, in other scales the listener rejected the tunings. The learned psychological responses of the listener were deemed to be accomodated to the scales within which the interval relationships were presented. The micro-tonal distinctions in the work of composers thereby becomes better understood and the tapestry of differentiated colors is greatly enhanced.
Phase locking to tones in avian auditory-nerve fibers
Authors: Woolf N. K. , Sachs M. B.
Published: October 2005

Frequency discrimination in songbirds is considerably worse than that in mammals for frequencies less than 1.0 kHz, even though tuning in avian auditory-nerve fibers is at least as good as that in cat. One possible source of the discrimination difference between these classes could be differences in the ability of auditory-nerve fibers to phase-lock to tones at these low frequencies. We have recorded the responses to characteristic-frequency tones from auditory-nerve fibers in the redwinged blackbird (Agelaius phoeniceus). The discrete fourier transform of the resulting period histogram was computed. The magnitude of the fundamental component in this transform (normalized by average discharge rate) is called the synchronization index, Sf. The maximum value of Sf across sound levels is the “level-maximum of Sf” [D.H. Johnson, Ph.D., thesis, (MIT, 1974)]. The level maximum of Sfd as a function of fiber characteristic frequency for the redwing is very similar to previously published results for cat auditory nerve [Johnson, ibid.]. For frequencies below 1.0 kHz, Sf is in the range of 0.75–0.95. At higher frequencies Sf decreases, approaching zero at about 6.0 kHz. The form of this high frequency decline is similar to that found in cats. Thus, it does not appear that poor frequency discrimination in birds results from poorer phaselocking at the level of the auditory nerve. [Supported by NINCDS.]
Estimate of speaking rate
Authors: Quinn A. , Umeda N.
Published: October 2005

A technique is described for estimating a person's speaking rate from a short utterance. Four speakers read aloud four stories and also a randomized list of the sentences from those stories. An average time per phoneme was calculated for each sentence from the ratio of total speech time (excluding pauses) to the number of phonemes in the sentence. The longest average duration in these data is 66.4 msec per phoneme; the shortest, 59.6 msec per phoneme. Variation in average duration decreases as sentence duration increases. The story version shows a less variable distribution than the list version. In the story version, all sentences longer than 5 sec have average phoneme durations that fall within ±5 msec of the speaker's overall mean phoneme duration, whereas the list version requires sentences 7 sec long to reach this stability.
Time-order-error in judgment of prosodic features—pitch, loudness, and duration
Authors: Chuang Chiu-Kuang , Wang William S-Y.
Published: October 2005

For years the time-order-error (TOE) in sequential comparison of speech stimuli was regarded primarily as an error interferring with the judging process of the perception task and eliminated from experimental result by means of ordering cancellation. In psychophysical experimentation many studies (Fechner, 1928; Stevens, 1934; Postman, 1941) have shown that the TOE was not simply a random error, but has possible neurophysiologic bases (Stevens, 1934). In perceptual evaluation of pitch [C-K. Chuang and W.S-Y. Wang, J. Acoust. Soc. Am. 60, S92(A) (1976)], loudness (C-K. Chuang and W.S-Y. Wang, AAAS 48) and duration [C-K. Wang, I. Lehiste, C-K. Chunag, and N. Darnovsky, J. Acoust. Soc. Am. 60, S92 (A) (1976)] from synthetic vowels, TOE was found to be a positive 12% for pitch discrimination, a negative 9% for loudness discrimination and a negative 5% for duration discrimination. Statistical test of the biased distribution mean demonstrated that all TOE's were significant at the 0.01 level. The corresponding quantitative values of those TOE's were 0.3% of F0, −0.6 dB of intensity and −2.1% of time interval (syllabic length) increment of the given physical value of the second stimulus respectively. In other words, because TOE exists perceptually, a pair of physically identical stimuli are always evaluated as if the F0, intensity, and the syllabic length of the second member of the pair were higher, lower and shorter respectively than the first member. Possible speculation of the physiological bases of these TOE mechanisms will be discussed. [Work supported by NSF grant 76-00017 and partially supported by NS 13274.]
Further work on duration modelling in reiterant speech
Authors: Liberman M. Y.
Published: October 2005

Durational patterns in reiterant speech (mimicry of natural “target” utterances while substituting a nonsense syllable, such as [ma], for each syllable of the original) have previously been argued to be stable over repetition, and to be relatively independent of the segmental characteristics of the target utterance [M. Y. Liberman and L. A. Streeter, J. Acoust. Soc. Am. 60, S27(A) (1976)]. A simple additive model of the relationship between linguistic factors (stress, rhythmic grouping, constituent structure) and reiterant speech durations has been shown to work reasonably well for a limited set of data [M.Y. Liberman, J. Acoust. Soc. Am. 61, S90(A) (1977)]. A larger, more systematically designed data base is being collected, the analysis of which should bear on the choice of linguistic factors and the function mapping them onto durations.
Acoustic study of juncture perception
Authors: Dukes Kathleen D. , Nakatani Lloyd H.
Published: October 2005

Juncture perception as a function of word-initial phonemes was examined in pairs of phrases contrasting in juncture location (e.g., “he praises” and “heap raises”). Contrastive phrases such as this with a wide variety of consonants, consonant clusters, and vowels at the juncture were recorded in sentence contexts by four talkers. The phrases were excised from the sentences and played to listeners who indicated which phrase they heard. Spectrograms of the phrases were examined for acoustic cues related to the results of the listening test. Juncture perception was good when a word-initial phoneme had a special feature not found in its word-final position, such as aspiration of initial voiceless stops and a glottal stop, laryngealization, breathy voice, or a drop in pitch at the onset of initial vowels. Juncture perception was poor when the same consonant occurred before and after the juncture (e.g., “heap praises”) even when the duration of the doubled consonant was twice as long as the single consonant. The acoustic results suggest that phonemic duration is not an important cue to juncture perception.
Adaptive probabilistic process for speech segmentation
Authors: Cohen Jordan A.
Published: October 2005

A classical and as yet unsolved problem in speech research is that of segmenting running speech, either as an end in itself, or as a part of a segmentation and labeling task. This paper reports an adaptive process using a modification of the Viterbi algorithm, in which a simple Markov model is applied to running speech. This method is flexible as well as being computationally tractible. The results of the automatic process are compared with segmentation derived from careful manual marking.
Expectation affects identification by listening
Authors: Ladefoged Peter
Published: October 2005

Recordings were made of 11 members of the UCLA Phonetics Laboratory group. At the time of the experiment there were two American Black speakers in the lab group, neither of whom was recorded. Instead another Black male who was relatively unfamiliar to most of the group was recorded. The recordings were made over the lab telephone, and spectrographic analysis showed that the frequency range was 100–4000 Hz. The recordings were edited and played to ten members of the lab group, who were simply asked to identify the speakers. All the listeners except one correctly identified all the 11 members of the lab group. Three of the listeners knew the Black speaker and identified him, two said they could not recognize this speaker, and five (including two phoneticians with Ph.D.'s and two post-M.A. phonetics students), wrongly identified him as one of the two Blacks in the lab.
Attributions made to acoustically manipulated voices
Authors: Streeter Lynn A. , Apple William , Krauss Robert M.
Published: October 2005

Spoken language contains information about the speaker, which can be transmitted by suprasegmental variables. We examined the effects of independently manipulating f0 and speech rate on judgments of several state variables and personality traits. Male speakers answered interview questions and were randomly assigned to one of nine cells—three pitch (low/unmanipulated/high) by three rate (slow/unmanipulated/fast). Speech material was analyzed using linear predictive coding. Pitch was scaled up or down by 20% of the original f0, whereas rate was expanded or compressed by 30%. Resynthesized utterances were rated by listeners on a number of scales. High-pitched or slow-talking speakers seem particularly undesirable; high-pitched speakers were judged as less truthful, weaker, and nervous and slow talkers were judged as less truthful and passive. An utterance's content, presumably mediated by the question topic, also influenced state and trait attributions.
Array directivity index with directional hydrophones
Authors: Brenin Barry
Published: October 2005

The Directivity Index (DI) of an array of identical hydrophones is expressed as the algebraic sum of three terms. One term is the array DI, to be calculated using the hydrophone directional response. The second term is a basic hydrophone gain, independent of array steering, and the third term allows for the hydrophone response in the direction of array steering. Using the covariance approach, the key to calculation of the array DI is knowledge of the correlation between the noises in two array elements, including hydrophone response. This correlation function is derived for an isotropic noise field, for narrowband and wideband cases. Computations using a modeled hydrophone response are shown for selected eases of array steering and shading, as a function of frequency for rectangular arrays. The results indicate a net DI approximately 3dB more than for an omnidirectional hydrophone, as if an infinite, ideal baffle were used behind the array.
Power transformer noise emissions
Authors: Vér István L. , Andersen Douglas W. , Myles Mark M. , Teplitzky Allen M.
Published: October 2005

This paper presents the results of an experimental study of the sound radiation of in-service power transformers in the 20-MVA to 300-MVA range. It was found that (1) for transformers in the power range of 20–30 MVA, the 120 Hz tone and for transformers with power rating above 30 MVA the 240 and 360 Hz tones control the A-weighted noise emissions; (2) changing the standard transformer noise rating procedure to include measurement of the first four tones at NEMA positions would increase the accuracy of farfield noise predictions; (3) the circumferential variation of both the tone and A-weighted levels, measured at 50 and 100 ft, approximate a Gaussian distribution with ω =4 dB for each of the first four transformer tones and ω =1.75 dB for the A-weighted level; (4) the relation between the level measured at NEMA positions, L̄N, and at distance d, L̄d, is L̄d=L̄N−20 log (d) +10 log(S) −8, where d is the distance in ft. and S is the area of the vertical tank surface in ft.2; (5) it was found that changes in load had negligible influence on noise emissions. [Work was supported by the Empire State Electric Energy Research Corp., New York, NY 10020.]
Prediction of machinery noise radiation using the CHIEF algorithm
Authors: Saha Pranab , Hadden W. James , Usry Gerald R.
Published: October 2005

This paper describes the application of the Combined Helmholtz Integral Equation Formulation [H. A. Schenck, J. Acoust. Soc. Am. 44, 41–58 (1968)] to the prediction of noise radiated from machinery with relatively smooth casings under steady running conditions. The CHIEF algorithm requires that the surface vibration distribution be specified as input. Several test cases, involving a rectangular parallelepiped resting on a rigid surface, are discussed. An experimental test is described in which a fluid-filled boxlike structure with pure-tone excitation was used. The comparison between sound pressure levels measured far from the structure and those computed from measured surface accelerations is very good.
Status report on bus noise abatement technology
Authors: Kouts Christopher A. , Kevala Russ J.
Published: October 2005

The EPA in its new product noise regulation development process, has defined best available technology as that noise abatement technology available which produces the greatest achievable, meaningful reduction in the noise produced by buses. The EPA considers that the noise level for regulatory purposes “achievable through the application of best available technology” is the lowest noise level, which can be reliably predicted based on engineering analysis of products subject to a standard that manufacturers will be able to meet by an effective date, through the application of currently known noise attenuation techniques and materials. This paper will present some of the significant progress in bus noise abatement technology that EPA has reviewed since the inception of the bus noise regulatory study which began in May 1975.
Application of a discrete element method in analyzing concentric tube resonators at high sound pressure levels
Authors: Sullivan J. W. , Crocker M. M.
Published: October 2005

In muffler design for internal combustion engines, concentric tube resonators are often used to provide high frequency attenuation. These resonators are constructed by shaping a rigid shell around a length of perforated tube, forming an unpartioned cavity. At high sound pressure levels typical of exhaust systems, these resonators exhibit significant degradation of peak transmission loss caused by the nonlinear behavior of the perforate. In order to analyze this condition it is necessary to account for the variation of the impedance of the perforate along the length of the tube for a resonator with specified input and output boundary conditions, and a specified source strength. This is accomplished by combining an empirically derived model of the perforate with an iterative solution of a discrete element model of the resonator, described in a companion paper. Results show that this procedure can accurately predict the performance of resonators at high sound pressure levels, and can be used as a design tool to optimize resonator configurations. [Work supported by Arvin Industries.]
Practical means for reducing saw noise
Authors: Allen Clayton H.
Published: October 2005

A vibration damper for circular saws, described at the San Diego meeting in 1976 was shown to give about 14 dBA of noise reduction. It has been improved and prototype models are being tested preparatory to the anticipated manufacture and distribution of products for quieting saws ranging from 10 to 24 in. in diameter as used in commercial processing of wood, metal, and plastics. The present paper will relate the results of the continuing developments by The Clayton H. Allen Corporation at Cambridge, Massachusetts, and by its prospective licensee, The Brunswick Corporation at its laboratory in Deland, Florida, and at its wood plant in Muskegon, Michigan. Noise reductions of up to 20 dBA have been obtained in cutting dry maple as measured in the reverberant field approximately 8 ft from a 10-in. saw.
Gruneisen numbers and hypersonic attenuation in hexagonal crystals
Authors: Nandanpawar M. , Rajagopalan S.
Published: October 2005

Expressions for Gruneisen numbers in various directions and for different modes are available in literature for cubic and trigonal crystals only. In the present work, different directions of pure elastic wave propagation in hexagonal close-backed structures have been considered and expressions for Gruneisen numbers for these directions have been formulated for the first time. Gruneisen numbers and the nonlinearity constant of magnesium have been calculated making use of the expressions derived. Akhieser attenuation in magnesium along the 〈100〉 axis has also been estimated in the temperature range 50–300 K. Variation of density, Debye characteristic temperature and thermal conductivity with temperature has been duly considered in our estimations. However, the nonlinearity parameter has been treated as temperature independent due to the nonavailability of data on the temperature variation of the third-order elastic moduli of magnesium. Our calculated value of the Gruneisen number, averaged out for 29 pure modes is in good agreement with the value estimated from the experimental data on the thermal expansion coefficients and the second-order moduli.
Acousto-optic effects in nematic liquid crystals
Authors: Letcher S. V. , Lobrun J. , Candau S.
Published: October 2005

Acoustically induced birefringence has been studied in homeottopic cells of nematic liquid crystals. Annular rings associated with the edge of the ultrasonic beam have been observed in agreement with the model based on acoustic streaming. Other observed features of the spatial distribution of the optical signal are not described by this theory. The increased sensitivity near the nematic-isotropic transition is shown to be due primarily to the increased sound absorption. [Supported by DRMF Contract 76/457.]
A 1-MHz linear phased array ultrasound system for imaging the major intracranial arteries
Authors: Barnes R. W. , Riley W. A.
Published: October 2005

A linear phased array ultrasound system has been constructed to image the major intracranial arteries from the superior surface of the cranium. The transducer array consists of 20 elements, 1.54 mm wide and 15 mm long, with an interelement spacing of 0.19 mm. Ten elements are excited for each transmit pulse and excitation pulses are phased for nominal transmit focus of 7 cm. On the receive side, echo signals from each element are logarithmically compressed and dynamically focussed by variable delay lines to within ±25 ns of an ideal phase coherent system at the input to a summing amplifier. The transmit/receive response results in a −6 dB beamwidth of about 6 mm at a depth of 7 cm. A two-dimensional image is formed by sequencing consecutive ten elements along the array. The major intracranial arteries imaged include the internal carotids in the intradural pertion of the siphon, the middle cerebrals as they travel laterally from the internal carotid arteries, the basilar artery, the posterior cerebral arteries as they follow the lateral aspect of the midbrain, and the perical-losal artery as it travels posteriorly along the superior surface of the corpus callosum. It is our interest to interface this linear phased array system with an on-line digital moving target indicator system to produce a two-dimensional image of only the intracranial arteries. [Work supported by NINCDS grant NS-06655.]
Effects of temperature on the aging rate of piezoelectric polymer
Authors: Powers J. M.
Published: October 2005

Results of aging measurements at 20°C, 57°C, and 66°C are presented for commercially available piezoelectric polymer (28-μm thick, poled polyvinylidene fluoride). The g31 (electric field/stress) and d31 (charge density/stress) piezoelectric constants were measured by a static dead weight tension test. The relative dielectric constant K33T was obtained from a 1-kHz capacitance measurement. At room temperature (20°C), aging rates of 10%/time decade for g31, 15%/time decade for d31, and 7%/time decade for K33T were obtained over a 100-day period from date of poling. Values of g31 and K33T were measured (at room temperature) for samples held at 57°C and 66°C for 100 days starting at 400 days from poling. For the 57°C case, g31 values at 401, 410, and 500 days showed a 3%, 10%, and 16% decrease over the 400-day value. The 66°C case showed decreases of 16%, 19%, and 21% in g31 over the same time period. No change in K33T was observed for either of these cases. [Work supported by R. R. Smith, Code 302, Naval Ocean Systems Center, San Diego, CA.]
Experimental determination of acoustic properties using a two-microphone random-excitation technique
Authors: Ross D. F. , Seybert A. F.
Published: October 2005

An experimental technique is presented for the determination of normal acoustic properties in a tube, including the effect of mean flow. White noise is used to produce a randomly fluctuating sound field and two stationary, wall-mounted microphones measure the sound pressure at arbitrary but known positions in the tube. Theory is developed, including the effect of mean flow, showing that the incident- and reflected-wave spectra, and the phase angle between the incident and reflected waves, can be determined from measurement of the auto- and cross-spectra of the two microphone signals. Expressions for the normal specific acoustic impedance and the reflection coefficient of the tube termination are developed for a random sound field in the tube. Three no-flow test cases are evaluated using the two-microphone random-excitation technique. Comparison is made between results using the present method and approximate theory and results from the traditional standing wave method. In all cases agreement is very good. [Research conducted at Purdue University, Lafayette, IN.]
Acoustic window model
Authors: Kilpatrick J. F.
Published: October 2005

A model was developed to predict the effect on the beam pattern of an array caused by the presence of a rigid, semi-cylindrical acoustic window. Using the basic theory of Brekhovskikh and previously proven methods of loss measurement and prediction, [E. E. Mikeska and J. A. Behrens, J. Acoust. Soc. Am. 59, 1294–1298 (1976)] the amplitude and phase distortion of the window can be predicted as a function of angle of incidence and frequency. This information, coupled with the relative geometries of the window and array, can be used to determine the beam pattern of the array/window combination. Theoretical patterns were compared with measured data on a high resolution line array with excellent results.
Relationships between combination tones and psychophysical suppression
Authors: Shannon Robert V.
Published: October 2005

Psychophysical measures of combination tone level and suppression were obtained in the same subjects. Cancellation and compared. For all subjects the pulsation thresholds were lower than the cancellation levels. For three of the four subjects the difference between these two measures was equal to the amount that the cancellation tone was suppressed by the lower primary tone f1. The cancellation results are possibly over-estimates of the combination tone levels because the cancellation tone itself is suppressed by f1. With the level of the lower primary fixed and the level of the upper primary increased, the combination tone level first increased and then decreased for both cancellation and pulsation threshold measures. The point at which these functions turn over is the same level at which the upper primary starts to suppress the lower primary.
On the representation of vowel formants in pulsation—threshold measurements
Authors: Lundström Eva , Carlson Jan , Lindblom Björn
Published: October 2005

Our aim in this research was to obtain masking patterns for stationary vowels via the experimental situation, known as the pulsation-threshold paradigm (Houtgast, 1974), in which a subject listens to two alternating signals: a masker and a probe signal. Houtgast has argued that the data obtained by this method reflect (a) and “auditory” spectrum, and (b) evidence of a mechanism of lateral inhibition in human hearing. Maskers were 12 synthetic vowels. Masking curves were compared with harmonic spectra and analyses in terms of case 13-octave filter bands. These comparisons indicated that representation of formants in threshold curves may differ from that of case 15-octave filter analysis. At frequencies corresponding to bands containing formant peaks, thresholds were often raised whereas at frequencies of adjacent bands thresholds were lowered. As a result the thresholds exhibited formant peaks that were “sharpened” in relation to the formant representation of the filter analyses. These results agreed with some of Houtgast's preliminary observations on vowels. Whether this should be taken as evidence of lateral inhibition in auditory representation of vowels or reflects effects associated with a pulsation-threshold measuring paradigm remains to be investigated.
Backward and forward masking in normal and hearing-impaired listeners
Authors: Cudahy Edward
Published: October 2005

Backward- and forward-masking patterns for a 10-msec probe with a 10-msec masker were measured for normal and hearing-impaired listeners in a 2IFC adaptive procedure. The probe and masker were equal in frequency. In previous work masker level has been kept constant and probe level has been varied. The present study employed a procedure analogous to psychophysical tuning curve measurements, i.e., probe level was kept at a constant sensation level and masker level was varied. Masker level at masked threshold was measured as a function of delay of prove relative to masker for probe sensation levels of 10 and 30 dB and for probe frequencies of 1 and 3 kHz. In general, hearing-impaired S's showed broader than normal masking patterns in both backward- and forward-masking conditions at both signal levels. Masking patterns narrowed for both groups of S's as signal level was increased. Some possible implications of these results for temporal processing by hearing-impaired listeners will be discussed.
Individual differences in valuation of perceived speech qualities
Authors: Voiers W. D.
Published: October 2005

Fifty subjects used a 20-item rating to characterize more than 100 samples of processed speech, representing every major class of speech coding system under various transmission conditions and also numerous simple types of laboratory degradation. Ratings were made with respect to 17 perceived speech qualities, intelligibility, pleasantness, and overall acceptability. Correlations between ratings of acceptability and ratings of other subjective qualities were calculated for each subject. These correlations served as indicants of the values attached to the various qualities by the individual subject. Intercorrelations among these indicants were factor analyzed to identify the elementary dimensions of interindividual variation in preference or taste. The results indicate that individuals vary with respect to at least four orthogonal dimensions of taste, one of which is the noise-versus-distortion dimension previously suggested by the results of McDermott [B. J. McDermott, J. Acoust. Soc. Am. 45 774–781 (1969).]
Articulatory characteristics of fluent esophageal speakers for selected english consonants
Authors: Hasegawa Akera , Christensen J. M. , Fletcher S. G. , McCutcheon M. J.
Published: October 2005

Linguapalatal contact characteristics and lip and mandible coordination of three fluent alaryngeal esophageal speakers were examined during the production of English consonants /p, t, k, s, b, d, g, z/ in CVC syllables (V = /æ/) embedded in a sentence “_____ is a word.” Pseudopalates with 96 electrodes were fabricated for each subject. Small light reflecting beads were placed on the lips and on cantilevers attached to mandibular and maxillary teeth to determine lip and mandible movements. Information on linguapalatal contact, lip and mandible positions, and voice spectrum were collected every 10 msec with the PAGIS instrumental system. Linguapalatal contact patterns were analyzed with reference to those of normal speakers in terms of place and duration of contact. The contact patterns were related to lip and mandible positions for the criterion CVC syllables. The results will be discussed with respect to known functions of speech physiology. [Supported by NIH grant NS-11852-02 and by NIH grant RR-5349 awarded to the first author.]
Duration of selected fricatives produced by esophageal speakers
Authors: Christensen J. M. , Weinberg Bernd
Published: October 2005

This paper describes the results of an acoustic study of /s/ and /z/ durations uttered by nine normal and nine esophageal speakers. Stimulus materials were eight symmetric CVC syllables formed by combining /s/ and /z/ with four vowels (/i/,/I/,/a/,/u/). Audio recordings of each subject uttering these syllables within a frame sentence were phonetically transcribed by a listening panel. Only those syllables meeting representativeness criterion were spectrographically analyzed (approximately 87%). Comparisons between syllable durations for the two groups were statistically nonsignificant; however, intrasyllabic differences for the /s/ symmetric syllables proved to be otherwise. Even though the esophageal speakers in this study maintained /s/ and /z/ durational relationships for voicing contrast, the ratio of preceding vowel duration to word-final voiceless fricative duration was altered. Vowel durations were significantly longer and the word-final fricative /s/ was significantly shorter. These findings suggest that total laryngectomy surgery produces substantial changes in articulatory maneuvers as used by esophageal speakers. [Work supported by The American Cancer Society.]
Discrimination of formant transition tempo by hearing-impaired listeners
Authors: Revoile S. , Wilson Mary Pat , Pickett J. M.
Published: October 2005

The rate of frequency change (tempo) of formant transitions can serve as a perceptual cue for differentiating certain speech sounds. As part of a project to study the speech discrimination problems of the hearing impaired, we examined the discrimination of transition tempo by 20 moderate-to-severely hearing-impaired listeners and five normal listeners (S's). The impaired S's were divided into flat or sloping groups on the basis of the audiometric configuration of their hearing impairments. Initial transitions were used that rose in frequency by either 100, 200, or 3OO Hz to steady-state formants at either 500 or 1500 Hz. For all groups of S's discrimination of transition tempo was better at 500 Hz than at 1500 Hz. At either frequency, discrimination of tempo worsened as transition frequency size decreased. Between the groups of hearing-impaired S's the sloping group discriminated transition tempo better than the flat group. The group of normal-hearing S's discriminated tempo better than either hearing-impaired group. Within the groups of impaired-hearing S's, large individual differences occurred in ability to discriminate transition tempo.
Identification of acoustically altered environmental sounds
Authors: VanDerveer Nancy J.
Published: October 2005

After identifying 40 tape-recorded environmental sounds, five groups of listeners heard acoustically altered tapes containing the same items in a new order. Each group received a differently altered tape: time-reversed, half-speed, double-speed, low-pass-, and high-pass-filtered (with 2-kHz cutoff) tapes were used. Listeners rated each item for familiarity and attempted to identify it. As predicted, each alteration yielded a different pattern of results over items, measured by percent correct identification. The reversed and the speeded tapes produced the worst performance (46% and 48%, respectively), the high-pass-filtered tape the best performance overall (62% correct). Most highly correlated in their effects over items were the speeded and the slowed tapes (r = 0.70); the reversed and the low-pass-filtered tapes produced the least similar effects (r = 0.37). Results are interpreted as demonstrating the importance of high-frequency and temporal pattern types of acoustic information for the perceptual identification of common environmental sounds.
Categorical perception of nonspeech stimuli by musicians and nonmusicians
Authors: Raz I. , Brandi J. F.
Published: October 2005

Categorical perception refers to a mode of perceptual processing by which successive stimuli drawn from a physical continuum are perceived as members of discrete categories. The present experiment studied categorical perception of non-speech stimuli. Fifteen rhythmic patterns (three-tone sequences) were produced. Each pattern differed with respect to the temporal position of the second tone within the sequence. Changes were made in 15-msec steps. Each tone was a 20-msec, 1000-Hz square wave with a 1-msec rise and fall time. Labeling and discrimination functions were obtained from 32 musicians (who were divided into two experimental subgroups) and 42 nonmusicians (who were divided into three experimental subgroups). The subgroups differed with respect to the order of presentation of the labeling and discrimination tasks. The results show that (a) all S's perceived the rythmic patterns categorically, (b) musical training affects labeling by sharpening categorical boundaries and improves discrimination performance, and (c) changes in order of presentation affect discrimination performance but not labeling performance.
Recognition of spoken spelled names applied to directory assistance
Authors: Rosenberg A. E. , Schmidt C. E.
Published: October 2005

The automatic word recognition system originated by Itakura has been modified to accept strings of spelled letters spoken in isolation. The output of the recognizer is a set of best candidate letters for each letter spoken in the string. Candidate strings forming spelled last names and initials are compared to name strings extracted from a telephone directory stored in a disk file. A systematic search is carried out to find a matching entry in the directory. The outcome of a search is one or more matches or no match. An evaluation of the system was carried out using the 17 000 entry Bell Labs telephone directory. A list of 50 randomly selected names was extracted from the directory. Ten talkers participated in the evaluation spelling out each name in the list over a dialed-up telephone line input to the system. In the initial input operation, the median error rate in acoustic recognition of the individual spoken letters may be as high as 20%, but the constraints imposed by the system in making the directory search reduce the error to less than 6% in the final identification of the name.
Effects of various types of speaker normalization on an automatic vowel recognition scheme
Authors: Sroka S. A.
Published: October 2005

This paper compares the effect of non-normalization, uniform normalization, and formant-dependent normalization on an automatic vowel recognition scheme. The data analyzed is that of Peterson and Barney [J. Acoust. Soc. Am. 24, 175–184 (1952)]. Vowel identity is determined by observed formant values. Normalization is accomplished by a multiplicative transformation of a talker's formant data such that the talker's average formant frequency agrees with some reference value. The results indicate that normalization does significantly enhance vowel identification and that the linear effects account for most of the male/female differences under the model used.
Probabilistic vector model for voicing mode identification of intervocalic stop consonants
Authors: Edwards T. J.
Published: October 2005

A probabilistic vector model was developed to identify the voicing mode of phonemically equivalent intervocalic stop consonants with an accuracy commensurate with trained listeners, such performance to be attained independently of the succeeding vowel's identity or the differences among talkers. Acoustic features known to be salient to the perception and production of stop consonants were studied as random processes whose probability density functions provided models for voicing mode identification. Each acoustic feature present in a stop's production then contributed a vector whose magnitude and direction were determined from the probability distributions resulting from these density functions. Stop recognition was the result of summing these individual vectors, with the resultant vector specifying the voicing mode of the stop under consideration. Acoustic features incorporated into the model were closure duration, stop-consonant duration, fundamental frequency, adjacent vowel amplitudes, burst amplitude, formant transitions, voicing during closure, and voice onset time. When the performance of the probabilistic vector model was compared with that of trained listeners, correct voicing mode identification was approximately 99.0% in both cases.