bluuebunny/crossref_metadata_2025 huggingface dataset:
Three models of phonation
Authors: Titze Ingo R.
Published: October 2005

Three models of phonation are described, one at the acoustic level, one at the kinematic level, and one at the biomechanic level. The models all feed the same vocal tract, which is the partial wave (Kelly-Lochbaum) transmission-line analog. The first source model is noninteractive with the vocal tract, the glottal pulse being computed by formula [Titze, J. Acoust. Soc. Am. Suppl. 1 68, S71 (1980)]. The second model is interactive in terms of the flow, but specifies vocal fold movement using a formula [Titze, J. Acoust. Soc. Am. 75, 570 (1984)]. The third is interactive in terms of flow and tissue movement, i.e., it self-oscillates. Comparisons are drawn between the three models in terms of quality of sound produced, input parameters specified, and nonauditory outputs derived. Vocal tract area input to the models has recently been modified to be compatible with the Haskins articulatory synthesizer (companion paper in this session), so that sentence-length utterances can be produced.
The stability of total phonational frequency range
Authors: Gelfer Marylou Pausewang
Published: October 2005

Previous studies of adults [M. Cooper and N. Yanangihara, J. Commun. Disorders 3, 261–266 (1971)] and children [M. Austin and H. Leeper, J. Commun. Disorders 8, 309–316 (1975)] have indicated that the lowest fundamental frequency (and, presumably, range of frequencies) an individual can phonate varies by 2–4 semitones at different times of the day and from one day to another. In the present study, subjects were instructed to produce both their lowest and highest fundamental frequencies three times in one day, and three times on a second day 4–6 weeks later. Fundamental frequencies were converted to the nearest semitone, and total phonational frequency range in semitones was calculated. The stability of highest fundamental frequency, lowest fundamental frequency, and total phonational frequency range was examined both within days and between days. Results indicate that although mean variation within days is similar to previous data (approximately + / − 2 semitones), variation over the 4–6 week period is somewhat greater. Further, some individuals showed variability of six or more semitones in various measures.
Fresnel zone radiation of underwater sound created by transient moving spatially modulated patterns of laser-generated heat deposition
Authors: Hsieh Hsiao-an , Pierce Allan D.
Published: October 2005

This analytical study further explores the feasibility of achieving strong farfield acoustic signals with a judicious design of the temporal and spatial pattern over which impinging laser-generated energy is added to the water surface. The heat q(x,z,t) deposited per unit time and volume decays exponentially with depth z and depends on horizontal distance x and time t in such a manner that the overall configuration has Gaussian envelope factors exp(− t2/T2) and exp[− (x − Vt)2/L2], the former causing the time interval of deposition to have a duration of the order of T. A third factor, 1 + cos[k(x − Vt)], in conjunction with the first, causes the configuration to move as a unit with speed V in the x direction. The inhomogeneous wave equation [B-T. Chu, NACA TN 3411 (1955)] is solved by Fourier transform techniques for the case when kL > 1, ckT > 1, kr > 1, but with kL2 not necessarily small compared with the acoustic propagation distance r. The principal analytical challenge is the evaluation of a double integral over angular frequency ω and wavenumber α; with judicious approximations we have succeeded in expressing the overall result as a linear combination of Fresnel functions of complex argument. Numerical results show a collimated beam of nearly constant frequency Vk propagating obliquely downward into the water with a gradually increasing beamwidth. [Work supported by ONR, Code 425-UA.]
Particle velocity detection using a thin membrane
Authors: Todoroff Douglas G. , Trivett D. H.
Published: October 2005

Underwater acoustic intensity measurements require the detection of both the acoustic pressure and the fluid particle velocity. The measurement of the acoustic pressure is easily obtained using conventional (pressure-type) hydrophones. The particle velocity may be obtained by measuring the flexural response of an appropriate membrane (constrained by an inertial structure) to the fluid particle velocity. Several thin (50–300 μm) membranes were constructed from materials which closely match (impedance, density) the acoustic medium. The use of low shear speed materials allowed for the construction of small (< 10 cm) membranes which are resonant (fundamental mode) to low-frequency fluid oscillations. The response of such membranes to the acoustic particle velocity and pressure is reported in the 0.02 to 0.5 ka range.
Measurement of radiation impedance of stepped piston radiator
Authors: Lubell Alan H.
Published: October 2005

It was noted in a paper given in 1972 [A. H. Lubell, J. Acoust. Soc. Am. 52, 1310 (1972)] that the radiation mass of a stepped piston underwater loudspeaker was approximately half of the value expected from simple piston theory. Recently, the integral equation approach was used to compute the radiation impedance for the Lubell Laboratories model 98 underwater loudspeaker and new measurements were made. This paper reviews the measurement and data reduction procedures and compares measured and theoretical radiation impedances. The original observation of reduced radiation mass is supported. A companion paper covers the integral equation computation. [This work was supported by Lubell Laboratories, Inc.]
Problems of defining criteria for protecting crew from ship motion effects
Authors: Thomas D. J. , Guignard J. C. , Willems G. J.
Published: October 2005

The single-frequency model of motion sickness incidence (MSI) developed by H. F. O'Hanlon and M. E. McCauley [Aerospace Med. 45, 366–369 (1974)] does not reliably predict MSI in complex oscillation typical of ship motion, as was shown by systematic measurements of MSI during combined heave motions [J. C. Guignard and M. E. McCauley, Aviat. Space Environ. Mede. 53, 554–563 (1982)]. Clinical and physiological observations (complemented by inertial measurements of head motion) during dynamically simulated 48-h rough-sea deployments of a projected 2000-ton surface effect ship provided further insight into the phenomenon of seasickness. Sixteen of 19 fit young naval volunteers discontinued testing, because of severe motion sickness; and all experienced symptoms. Severe motion sickness caused abandonment of psychomotor task performance; but two subjects consistently resistant to sickness performed their tasks throughout the experiment (although experiencing some nausea and exhibiting post-run postural instability). Ataxia, and symptomatic motion sickness in some cases, persisted for several hours after motion. Habituation to motion severe enough to provoke continuing vomiting did not occur in these simulations, although there was indirect evidence of some transfer of habituation from prior single-frequency motion exposure. We recommend that motion effects be studied systematically in relation to the physical parameters of provocative motion. [Work of Naval Aerospace Medical Research Laboratory Detachment ♯ 1 (now Naval Biodynamics Laboratory), New Orleans; supported by Office of Naval Research. Views not necessarily those of the Department of the Navy. Archival data in letter report to ONR (1980) and Paper ♯9 to NATO/DRG Seminar, Toronto (1983).]
Prediction of the incidence of motion sickness from the magnitude, frequency, and duration of vertical oscillation
Authors: Lawther A. , Griffin M. J.
Published: October 2005

A method is proposed by which the incidence of motion sickness may be predicted from measurement of the motion exposure. The method is based on data from both field and laboratory studies involving large numbers of people and is applicable to marine and other environments where vertical oscillation occurs at frequencies below 1 Hz. The frequency-dependent nature of motion sickness is incorporated by the use of a frequency weighting curve. A procedure for summing motion exposure over time yields a cumulative measure reflecting the dependency of sickness on duration of exposure. The influence of motion in axes other than the vertical is considered and the effects of population variables such as sex, age, and experience are discussed. The method enables separate predictions to be made of vomiting incidence and of reported feelings of illness.
Strategies for building the undergraduate course sequence in architectural acoustics at the University of Florida Department of Architecture
Authors: Siebein Gary W. , Kinzey Bertram Y. , Morgan Charles F. , Burgess Peter
Published: October 2005

Over the past 10 years, the undergraduate coursework in architectural acoustics at the University of Florida Department of Architecture has evolved from a several week segment of a one semester course in Environmental Technology (which is a format typical of many schools of architecture) to a sequence where material will be covered in portions of courses in the second, third, and fourth years of study. This system was developed to respond to two basic educational needs. First, it provides the opportunity to reinforce basic concepts, hopefully increasing the students' level of comprehension. Secondly, it allows additional depth to be added in each successive year so that the level of work in the technology class closely parallels the level of work in the studio course at a given year. The process of curriculum development (struggles) used to build this course sequence as well as the development of teaching materials and methods (strategies) used in the courses will be surveyed.
Development of acoustics program at the University of Nevada, Las Vegas
Authors: Reynolds Douglas D.
Published: October 2005

The undergraduate program in Mechanical Engineering at the University of Nevada Las Vegas is less than 3 years old. The undergraduate program contains a required vibrations course and an elective noise control course. The School of Engineering at UNLV is in the process of designing a 101 000 sq ft engineering building that will house all of the engineering and computer science programs. The building will contain laboratory facilities that will include an anechoic chamber, double reverberation chambers, and a 60 000 CFM fan, and duct system connected to the larger reverberation chamber for conducting sound tests of duct elements under actual flow conditions. These facilities will be used both for demonstrations of principles associated with acoustics and with noise and vibration control and for undergraduate and graduate research projects. The author will present the procedures that were used to incorporate acoustics in the undergraduate curriculum and to develop the acoustics research facilities that will be incorporated in the new engineering building as UNLV.
Strategies and struggles of incorporating acoustics in undergraduate curriculum
Authors: Plummer Ralph W. , Stobbe Terrence J. , Mogensen James
Published: October 2005

This paper relates the philosophy of the authors concerning the introducing of integration of basic acoustical principles into junior and senior level courses. The curriculum presents basic instruction in sound measurement, the effects of noise on human performance, and acoustical control in a junior level course and reinforces these concepts plus additional instruction in acoustics in a senior level course. The paper explains the strategy and reasoning of this approach, relating both strengths and weaknesses.
Preliminary observations on the production and perception of clapping
Authors: Repp Bruno H.
Published: October 2005

Clapping is a rhythmic human activity that communicates approval and, possibly, individual characteristics such as size, sex, and personality. It seems to have been studied little, even though there are interesting questions to be asked about motor control, individual differences, development, and perception. In this pilot study, ten male and ten female subjects were recorded clapping at their most comfortable rate. Spectral and temporal measures were obtained, and the same subjects (all known to each other) participated in a “clapper identification” experiment. While absolute identification was predictably poor, subjects' responses were quite systematic, mainly due to a tendency to associated slower rates of clapping with male individuals. Males, in fact, clapped somewhat slower than females, whereas there was much systematic spectral variability unrelated to sex. Several principal dimensions of spectral variation were derived by factor analysis, and an attempt was made to relate them to parameters of hand configuration.
Familiar voice recognition and unfamiliar voice discrimination are independent and unordered abilities
Authors: Van Lancker Diana , Kreiman Jody
Published: October 2005

One-hundred and ten normal and thirty-two brain-damaged (BD) subjects were tested on voice discrimination and voice recognition protocols. The recognition task included samples of famous male voices in a multiple-choice format; the discrimination test consisted of pairs of male voices in a same-different task. Three findings suggest a dissociation between the two abilities. (1) Scores on the two tasks were only slightly correlated in normal subjects and were not significantly correlated in BD subjects, suggesting no obligatory relationship between performance on one task and performance on the other. (2) RBD subjects performed significantly less well than normal controls in recognition, while LBD subjects did not differ from normals; brain damage in either hemisphere affected discrimination abilities. (3) Nearly half of the BD subjects showed very large discrepancies between scores on the tasks, with chance performance on one alongside normal scores on the other. These asymmetries in performance occurred in both directions, indicating that discrimination and recognition are independent, unordered processes. Examination of CAT scans suggests that voice recognition is impaired only in right-posterior BD, while voice discrimination is impaired in damage to the temporal lobes on either side.
Influence of fundamental frequency in the perception of vowel height
Authors: Di Benedetto Maria-Gabriella
Published: October 2005

Acoustic analysis of the vocalic portions of CVC nonsense syllables spoken by three speakers (two males and one female) shows that, in the dimension representing vowel height, individual differences for low vowels are reduced when the vowels are represented by the difference F1-F0 rather than by F. For high and mid vowels, on the other hand, a smaller shift in the F1 dimension would be needed to correct the differences in F0. Vowel identification experiments using CVC synthetic stimuli show that an increase in F0 from 120 to 180 Hz does not result in a clear effect on the identification functions, while a variation from 120 to 240 Hz does result in consistently different judgments. In a second experiment, one formant stimuli with F0 = 120 Hz and various values of F1 (300, 350, 400, 500, 600 Hz) were matched against one-formant stimuli in which F1 was adjustable and F0 equal to 180 or 240 Hz. The value of F1 for best match was usually between an exact formant match, and a match yielding similar values of F1-F0 for comparison and standard stimuli. The match was close to F1 for low F1 and F0 = 180 Hz, and approached (but did not reach) similar F1-F0 for higher F1 and F0 values.
Acoustic waveform and wavefront structures from pulsed planar expanding ring sources
Authors: Warshaw Stephen I.
Published: October 2005

We extend previous work on analytic and semi-analytic time domain evaluations of Rayleigh's integral for the acoustic pressure field radiated by pulsed, planar expanding ring sources imbedded in an infinite rigid baffle [S. I. Warshaw, J. Acoust. Soc. Am. Suppl. 1 77, S60 (1985) and LLNL reports UCRL-91858, 93820 (1985)] to consideration of spatial waveforms and wavefront structure of these fields. The source is taken to be a finite circular membrane having a radially symmetric, normal surface acceleration distribution ɑn = f(r)δ(t − g(r)). We review the quadrature techniques we use to evaluate Rayleigh's integral, and for simple choices of f(r) and g(r) we present theoretically calculated near and intermediate pressure fields in the form of spatial pulse profile and pressure contour snapshots at different times. We discuss the various waveform features and wavefront structures evident in these fields, as well as effects of choices of f(r) and g(r). The analytic methods used here can and have been implemented on a pocket computer, and have been used to benchmark a large finite-element computer code developed to simulate acoustic fields from more dynamically complex planar sources. [Work performed under the auspices of the U.S. Department of Energy by LLNL under Contract W-7405-Eng-48.]
Variational principle for harmonic fluid-structure interaction applied to an unbaffled elastic disk
Authors: Ginsberg J. H. , Pierce A. D.
Published: October 2005

A variational principle for the pressure distribution along surfaces in harmonic motion was described in an earlier paper [A. D. Pierce and X. F. Wu, J. Acoust. Soc. Am. Suppl. 1 74, S107 (1983)]. That principle was limited to situations where the particle velocity at the surface is known. Such is the case when the vibration is specified, or when an incident wave is scattered from a rigid surface. Here we shall extend the principle to treat elastic structures that are excited either by a mechanical force or by an incident wave. The principle will be illustrated by an analysis of the surface pressure and vibration pattern along a thin, circular, unbaffled plate. It will be shown that the prior formulation, which used a set of assumed modes, may be combined with a modal description of the plate vibration. The new feature of the formulation, beyond that required to consider either pressure along a rigid structure or in-vacuo vibration, is the need to evalute a set of coefficients that describe the coupling between the fluid and structure modes. [Work supported by the Office of Naval Research, Code 432-F.]
Some compliance and piezoelectric properties of voided polyvinylidene fluoride (PVDF)
Authors: Moffett Mark B. , Powers James M.
Published: October 2005

Measurements of the compliances parallel and perpendicular to the stretched direction (s11 and s22, respectively) as well as the piezoelectric coefficients g31 and g32 were made for Thorn-EMI voided piezoelectric polyvinylidene fluoride. The measurement method, a simple mass-spring system fed into a dual-channel spectrum analyzer, is described. Although all four measured quantities increased monotonically with increasing temperature, no glass-to-rubber transitions were encountered within the (− 40 to + 30) °C and (200 to 1000) Hz temperature and frequency ranges covered. [Work supported by ONR Code 220B.]
A new method for measurement of drum head properties
Authors: Blackstad Peter , Rickey Martin E. , St-Amant Guy , Smith Wayne R.
Published: October 2005

For comparison of the theoretical predictions and experimental measurements of drums it is important to be able to determine the membrane tension and, in addition, any nonlinear or anisotropic properties of the membrane material. Such anisotropies can arise from the empirical methods used in the tuning of comtemporary drums in addition to the intrinsic properties of the membranes themselves. We have developed a new technique potentially applicable to a wide variety of drums. A modest and variable pressure differential is introduced into the body of the drum. This pressure is measured precisely with a water manometer. The drumhead displacement is measured with good precision in carefully selected locations and many interesting properties of the head can be determined. The results of initial measurements will be presented.
Line spectral pairs—Formant correlation in speech
Authors: Wood C. A. , Sawallis Thomas R.
Published: October 2005

Researchers have stated that “closely spaced” line spectral pairs (LSP's) tend to mark formants. [J. R. Crosmer and T. P. Barnwell, Proceedings of the ICASSP 85, Tampa, FL, 26–29 Mar. 1985 (IEEE, New York, 1985), Vol. 2, pp. 240–243.] None of the studies quantified the term “closely spaced” and gave little or no experimental evidence to support the statement. This paper compares visually determined formant areas from digital spectrograms and overlaid LSP tracks. Incremental threshold values using three different methods for the test of “closeness” were used to test and quantify that correlation experimentally across one syllable for many talkers and across many /hVd/ syllables for a male and female talker. Results show that the closer the LSP's the more probable they are to overlay a formant, that most false hits tend to occur in low energy (i.e., consonantal) areas, and that LSP's track F1 and F2 better than F3 and F4. Incidental evidence tends to counter Crosmer and Barnwell's claim that the closed glottis odd LSP coefficient will correspond approximately to the formant center frequency.
Multi-style training for robust speech recognition under stress
Authors: Lippmann Richard P. , Mack M. M. , Paul D. P.
Published: October 2005

A new training procedure has been developed to improve speech recognition performance when the talker is under stress and training tokens cannot be obtained in the recognition environment. Training tokens are obtained from the desired talker speaking both normally and with different talking styles (e.g., loud, soft, fast). The recognizer is then trained with all tokens and used under stress. This technique was tested with a, 35 aircraft-word vocabulary, 9 talker, 11 340 token, stress/style database. Two stress conditions included (1) workload stress created with a perceptual-motor critical-tracking task (2) intense noise presented through earphones at a 90 dB SPL level. A continuous-distribution speaker-dependent hidden Markov model recognizer was trained normally (five normally spoken tokens) and with multi-style training (one token each from normal, fast, clear, loud, and question-pitch talking styles). Error rates were 36% in noise and 12% under workload stress with normal training. Multi-style training reduced error rates substantially to 13% in noise and 9% under workload stress. Multi-style training also reduced the error rate for normally spoken words. [Supported by DARPA.]
Discrimination of synthetic-vowel formant amplitude change in F2, F3, with two pyschophysical methods
Authors: Gengel Roy W. , Hieronymus James L.
Published: October 2005

Estimates of ΔI are reported for amplitude changes in F2 of two-formant synthetic vowels and for amplitude changes in F3 for three-formant synthetic vowels. The vowels /æ, ɔ, i, and u/ were used. Four subjects were tested at an overall level of 70 dB SPL using both a same-different and a 3AFC procedure. The results suggest that ΔI for a “comparison” stimulus is dependent, in part, on the amplitude of F2 (or F3) relative to the amplitude of F1 in the “standard” stimulus. Thus, for example, when the dB level of F3 is low relative to the dB level in F1 (as in /u/), ΔI is comparatively large. When the amplitude of F3 is high compared to F1 (as in /æ/), ΔI is comparatively small.
Duration effects revisited: Labeling of tone analogs to voicing contrasts
Authors: Pastore Richard E. , Morris Crystle , Logan Robert , Layer Jody K.
Published: October 2005

Our previous research described at the last Acoustical Society Meeting [Pastore et al., J. Acoust. Soc. Am. Suppl. 1 77, S27 (1985)] investigated duration effects in the perception of tone analogs to the delayed F1 onset cue for voicelessness. Two groups of psychophysically experienced subjects exhibited statistically significant dependencies on stimulus duration, with longer stimuli resulting in shorter delayed onset boundaries. This pattern of results is opposite to those reported for voicing contrast boundaries as a function of target stimulus duration. The second group of subjects now has replicated this statistically significant reversed duration dependency for equivalent stimuli with added harmonic structure. Naive subjects with the identical task and stimuli exhibit a statistically significant dependency on duration consistent with published findings for synthetic speech, and thus opposite to that found for our experienced subjects. The results are discussed in terms of the role of perceptual learning in the perception of voicing cues. [Research supported, in part, by National Science Foundation grant 8302873.]
An ultrasonic ranging system for robot position sensing
Authors: Figueroa Fernando , Lamancusa John S.
Published: October 2005

Currently used robot position control systems consider only the joint angles when positioning an end effector in space. This approach can lead to serious errors due to structural deflection under load, backlash in joints, manufacturing tolerances, etc. A method is needed to directly measure the absolute position and orientation of the end effector in three-dimensional space in order to achieve positioning accuracy. An ultrasonic ranging system is proposed to accomplish this task. It consists of: (1) one or more transmitters mounted on the robot's end effector; (2) receivers (four or more required), mounted adjacent to the robot's work envelope; and (3) analog and digital electronics to drive the transducers, process the received signals, and calculate the position of the end effector. The end effector's position is calculated using the time of flight measured from the emitter to each receiver, by an intersection of spheres algorithm. The performance objectives of this system are: (a) measure position with accuracy of ± 0.001 in. (b) up to a range of 3 m. and (c) with at least 1-Hz update rate. A theoretical error analysis of the system is presented. Types of emitter signals are compared, operating frequency considerations are discussed, and hardware recommendations are made. [Work supported by NSF.]
Primitive musical instruments using Helmholtz resonators
Authors: Firth Ian M.
Published: October 2005

Measurements will be presented on some primitive musical instruments that produce sound from excitations of a Helmholtz resonator. Input acoustical response measurements will be compared with the sound output when the instruments are blown. In some instruments, pitch can be altered by changing finger position, but others have constant pitch. The complicated pigeon whistle which is attached to the legs of pigeons will be described. This lightweight whistle contains a large Helmholtz resonator and several quarter wave pipes, and is excited in flight by air streaming across sharp lips on each of the parts.
Vibrational modes of a Chinese two-tone bell
Authors: Sathoff H. John , Richardson B. R. , Hampton D. Scott , Rossing Thomas D. , Lehr André
Published: October 2005

Many ancient Chinese bells, by virtue of their oval shape, sound two distinctly different tones, depending upon where they are struck. These so-called sui and gu tones usually differ in pitch by about a minor third. The vibrational modes and sound radiation from a carefully dimensioned modern copy of a Chou dynasty (1030—221 B.C.) bell in the Dutch National Carillon Museum have been studied. The lowest modes, and many of the higher ones as well, occur in pairs, with one member having an antinode near the sui strike point and the other near the gu strike point. The frequency separation of these doublets is determined by the shape of the bell. The modal shapes, determined by holographic interferometry, are similar to those observed in round church bells, but with more mixed modes due to the greater damping.
Calibration of microphones for sound intensity measurements
Authors: Seybert A. F.
Published: October 2005

The two-microphone sound intensity method is potentially a valuable tool for noise source identification, sound power determination, and for other measurements (e.g., transmission loss) that are based on sound intensity measurements. An essential ingredient in an accurate sound intensity measurement is the accurate measurement of the phase between the two microphones. Because the phase is generally small, on the order of a few degrees, the microphones must either be “phase matched,” or a phase calibration procedure must be used. This paper outlines the design and test procedures for using a plane-wave tube to perform a microphone phase calibration with an uncertainty of less than approximately 0.2 deg. The phase calibration procedure is illustrated for a pair of condenser microphones and for a pair of miniature crystal microphones typically used in hearing aids.
Impedence matching in the design of constant directivity horns
Authors: McLean James , Hixson Elmer L.
Published: October 2005

A model capable of predicting impedance and power transfer characteristics of so-called “constant directivity” (CD) horns was developed and presented at the spring 1986 meeting of the Society [J. Acoust. Soc. Am. Suppl. 1 79, S90 (1986)]. It is well known that a CD horn does not exhibit flat frequency response because reflections occurring at the diffraction slot cause resonances in the matching section. This model has been used to apply distributed circuit design techniques to CD horns in order to reduce the resonant peaks in the driving point impedance of a particular CD horn, the JBL 2360. Modifying the matching section of the CD horn yields a more nearly constant and resistive driving point impedance without adversely affecting its constant directivity characteristics. Several alternative designs for the 2360 will be presented and the relative merits of each will be discussed.
Diffraction of acoustic waves by using the generalized ray theory
Authors: Ku C. George
Published: October 2005

The diffraction of transient waves by a curvilinear boundary using the theory of generalized rays is developed. The generalized ray integrals, which represent the Fourier transform of diffracted waves, involve a double integration with respect to two wave slownesses. The inverse Fourier transform of these double integrals are computed by applying the simultaneous transformation of variables and the Cagniard method. The phase functions of the integrand provide the ray paths of incident, reflected, and diffracted waves. Since the pulses arrive at a point of observation in successive order, the theory furnishes an exact solution up to the time of arrival of the next ray and enables one to analyze, in detail, the signals recorded by the receiver.
Diffraction of a rectangular beam by a crack edge
Authors: Harris John G.
Published: October 2005

Ultrasonic transducers, operating at microwave frequencies, radiate highly directional wave fields or beams. These beams are used to probe solids for defects such as cracks. To model this process, the compressional and shear waves reflected from a semi-infinite crack and diffracted from its edge when it is struck by a two-dimensional, compressional beam are calculated asymptotically. A beam whose initial cross section is rectangular is considered. The crack is assumed to lie in the nearfield or in the nearfield-farfield transition region of the incident beam. Thus the incident beam is only slightly divergent when it strikes the crack edge, and it ensonifies only a finite region of the crack surface. But this region acts as if it were a secondary aperture. Therefore, of particular interest in the calculation are the results showing how the reflected beam diverges as it propagates away from this secondary aperture and arrives at the aperture of the incident beam. [Work supported by NSF.]
Ray acoustic analysis of plane-wave coupling into large open waveguides: Plane parallel geometry
Authors: Felsen L. B. , Shirai H.
Published: October 2005

When a plane sound wave impinges on a wide open-ended baffled or unbaffled plane parallel waveguide, the behavior of the sound field coupled into the interior differs from that when the waveguide is tubular [H. Shiral and L. B. Felsen, this meeting]. The difference is due to the fact that plane waves retain their integrity between wall reflections. By application of ray theoretic, modal, and hybrid ray-mode methods, one may establish the connection between the geometrically sharply delineated multiple reflected sheet beam, the edge diffracted-multiple reflected ray fields, and the guided modes. For very strongly overmoded conditions, the significantly contributing modes are those whose plane-wave congruences have directions near that of the incident plane wave. Invoking ray-mode equivalences, a hybrid form is found to describe the propagation phenomena in a physically incisive and numerically efficient manner, especially the diffusion of the initially well-collimated sheet beam after undergoing multiple reflection. [Work supported by ONR.]
Ray acoustic analysis of plane-wave coupling into large open waveguides: Circular geometry
Authors: Shirai H. , Felsen L. B.
Published: October 2005

Sound penetration into large enclosures can be modeled approximately by ray methods. When these enclosures are elongated so as to admit simulation by a waveguide, the interplay between rays and guided modes becomes important. To clarify the relevant phenomenology, we examine the prototype problem of a rigid semi-infinite baffled or unbaffled circular waveguide. Using the methodology of the geometrical theory of diffraction (GTD) and its modification to account for a guiding environment [L. B. Felsen and H. Y. Yee, J. Acoust. Soc. Am. 44, 1028–1039 (1968)], the interior field for arbitrary plane wave incidence is constructed by edge diffracted-multiple reflected ray tracing, by modal expansion, and by physical optics (PO) applied to the aperture field. Stationary phase evaluation of the PO modal excitation coefficients establishes the connection with GTD, especially the mechanism of coupling from GTD into the modal fields. By reciprocity, the radiation problem can be handled in a similar way. Some conclusions are drawn for guides with noncircular cross section. [Work supported by ONR.]
Masking-level differences as a function of masker level: Revisited
Authors: Yost William A.
Published: October 2005

Measurement of the masking-level difference (MLD) has been suggested as a possible test for some types of hearing disorders. When MLDs are measured with hearing impaired patients, careful attention must be paid to the overall stimulus level and differences in sensitivity between the two ears. Studies done in the late 1960s proposed an explanation for the dependence of the magnitude of the MLD on masker level or interaural differences in masker level. This explanation assumes that additive internal noise present in the outer ear produces a significant contribution to the masking stimulus at the low signal frequencies typically used in studies of the MLD. The present paper will review this explanation and combine it with the predictions of the Durlach equalization-cancellation model of binaural analysis to fit the data from all the studies since 1948 that have investigated the MLD as a function of masker level or interaural masker level. In addition, data from a study using insert headphones will be described. The use of insert headphones, instead of the supra-aural headphones typically used to measure the MLD, should reduce the contribution to the masker of the additive internal noise present in the outer ear. [Work supported by the Air Force Office of Scientific Research, Life Sciences, and the National Institutes of Health, NINCDS.]
Envelope correlation preception
Authors: Richards Virginia M.
Published: October 2005

The ability to determine whether simultaneously presented noise bands have correlated envelopes was examined. In each interval of a 2IFC paradigm, two bands of noise, centered at frequencies f and f + Δf, were presented. In one interval, the two noise bands had identical envelopes, while, in the other, interval envelopes were uncorrelated. Four frequency regions were tested: f = 350, f = 1000, f = 2500, and f = 4000 Hz. Percent correct discrimination was determined as a function of both f and noise bandwidth. The ratio Δf/f ranged from 0.5–1. For f = 350 Hz, discrimination did not exceed chance. This agrees with the data of Schubert and Nixon [ONR Tech. Rep. NR 140, 253 (1970)]. In contrast, it was found that for the larger values of f, observers could readilly discriminate between the correlated and uncorrelated conditions. In general, as the frequency separation (Δf) increased, performance decreased. The exception to this rule occurred at f = 1000 Hz. For two of the three observers, performance at moderate values of Δf exceeded performance at both small and large values of Δf [Work supported by AFOSR and an NIH post-doctoral fellowship.]
Effect of spectral density and interaural parameters on profile analysis
Authors: Bernstein Leslie R. , Green David M.
Published: October 2005

Detection of a change in spectral shape was investigated by incrementing the central, 1-kHz component of a multitonal complex. Complexes consisted of equal-amplitude components spaced logarithmically from 200 Hz to 5 kHz. Detectability was investigated as a function of the number of components in the complex and certain interaural parameters. Stimuli were presented diotically or in one of several dichotic configurations. As reported previously, for the diotic stimuli, performance improves as the number of components is increased from 3 to about 21; further increases yield poorer performance. The data from the dichotic conditions, however, are somewhat different from the diotic conditions. Like the data of Green and Kidd [J. Acoust. Soc. Am. 73, 1260–1265 (1983)], they suggest that although spectral analysis can be achieved using information across ears, performance is inferior to that obtained with diotic stimuli. However, our dichotic data do not reveal as large a decrement in performance relative to the diotic condition. Also, it appears that, with dichotic stimuli, performance may be affected by the presence of binaural cues. [Work supported by AFOSR.]
Parametric study of onset effects in lateralization
Authors: Buell Thomas N. , Hafter Ervin R.
Published: October 2005

When lateralization signals made up of trains of high-frequency clicks (n per train), optimum usage of the information carried in each click results in binaural thresholds that decrease at the rate 1/n. However, when the interclick interval (ICI) is short, the relation between threshold and n is best described by raising n to the exponent k [where 0 ⩽ k ⩽ 1 and k = f(ICI)]. This implies that shorter ICIs produce greater dependence on information contained in the signal's onset, with k = 0 meaning that no information is derived beyond the first click in the train while k = 1 means that each click is equally effective. Based on discriminations of interaural differences of time (IDT), it will be shown that the relation between k and ICI is reasonably linear, ranging from a k of 0.0 for ICIs of 1–2 ms to k equal 1.0 for ICIs of about 11–13 ms. Interestingly, if the ICIs are made even longer, the k remains at 1.0 but the absolute performance grows worse. It is what one might expect if the internal jitter added to each sample of IDT was increased for widely spaced clicks but the observer was still able to integrate across the entire train. [Work supported by NINCDS.]
A weighted image model for binaural lateralization
Authors: Stern Richard M. , Zeiberg Andrew S.
Published: October 2005

A new model that predicts the subjective lateral position of bandpass binaural stimuli is described. As in other models, it is assumed that stimuli are bandpass filtered and rectified, and that the rectified outputs of filters with matching center frequencies undergo interaural cross-correlation. The results of these operations is a two-dimensional function R(τ, f) where f is center frequency, and τ refers to the delay parameter of the crosscorrelation operation. For many stimuli the modes of R(τ, f) form families of hyperbolae in the τ, f plane. Lateralization predictions are obtained from a weighted linear combination of the centroids along the τ axis of the trajectories of these modes. Individual trajectories receive greater weighting if they are straighter (i.e., more parallel to the f axis) and/or more central (i.e., closer to the f axis). The straightness factor enables the model to predict the preceived laterality of bandpass stimuli with combinations of interaural time delays and phase shifts, and amplitude-modulated stimuli with time delayed envelopes. This model is compared to other theories based on explicit processing of envelope information. [Work supported by NIH.]
The preception of complex echoes by an echolocating dolphin
Authors: Au Withlow W. L. , Moore Patrick W. B. , Pawloski Deborah A.
Published: October 2005

Dolphins echolocate with short broadband acoustic signals which have good time resolution properties. Received echoes are often complex, with many resolvable highlights or components caused by reflection of the incident signal from external and internal boundaries of a target and from different propagational modes within a target. A series of experiments was performed to investigate how dolphins perceive complex echoes. Echoes were produced by a microprocessor-controlled electronic target simulator which captured each emitted click and retransmitted the signal back to the animal after an appropriate delay time. The use of a “phantom” target allowed for precise control of the number of highlights, the time separation between highlights and the relative amplitudes of highlights in the simulated echoes. An echolocating dolphin was trained to perform a target detection task in the presence of masking noise using these phantom echoes. The properties of simulated echoes were systematically varied, and corresponding shifts in the dolphin's detection threshold were observed, allowing the inference of how the dolphin perceived the echoes. The dolphin performed like an energy detector with an integration time of approximately 290 μs.
Nasality and nasal airflow in English
Authors: Boisen Sean
Published: October 2005

This paper presents results from a general study of nasal airflow for a speaker of English. Nasal flow was recorded for approximately 1000 tokens in a carrier phrase, along with the audio output. The results support a hierarchical arrangement of vowels according to manifestation of nasal flow (in nasal environments) which parallels their oral impedance. This is consistent with acoustical studies of the effects of nasal coupling, as well as some perceptual studies, but differs in crucial ways from previous articulatory work. Other contextual segmental effects are observed, including a striking attenuation of the flow curve in final voiceless clusters. A revised definition of nasality, based on aerodynamic criteria, is advanced. Based on this definition, the circumstances under which nasality “spreads” was investigated, along with the flow characteristics of different segments. [Work supported by NIH.]
Vocal fold configuration associated with giottographic signals
Authors: Geratt Bruce R. , Hanson David G. , Berke Gerald
Published: October 2005

In recent years, glottographic techniques have been used more frequently to study vocal fold vibratory motion in clinical populations with voice abnormalities. However, some types of laryngeal pathology can result in deviant vocal fold movement, making interpretation of glottographic signals difficult. In the absence of other evidence, glottal events must be assigned to corresponding glottographic signals by inference usually from the study of normal phonation. This study was designed to confirm the relationship of simultaneously recorded photoglottographic (PGG) and electroglottgraphic (EGG) signals to vibratory movements of the vocal folds in the living human larynx. Photographs of the vocal folds were made using an 80-μs flash. The flash was recorded as an impulse on the PGG trace, indicating the location on the glottographic signals of the corresponding single-frame photograph displaying the glottal configuration. The instants at which the upper vocal fold margins first begin to open, separate completely, reach maximal lateral excursion, the lower margins first make contact, and close completely were documented. It appears that the timing of these events can be accurately identified in glottographic signals from normal and pathologic voices. [Work supported by NINCDS.]
Patterns of interarticulator phasing relations
Authors: Nittrouer Susan , Munhall Kevin , Kelso J. A. S. , Tuller Betty , Harris Katherine S.
Published: October 2005

The difficulty in identifying phonetic segments in the acoustic signal of speech is a commonly recognized problem. One proposed solution is that the integrity of individual segments is maintained by stable timing relations between the articulators. Recently, Kelso and Tuller [e.g., J. Acoust. Soc. Am. Suppl. 1 77, S53 (1985)] reported an invariant relation between jaw and lip gestures in various VCV contexts. Specifically, the onset of upper lip lowering for the intervocalic consonant was found to have a constant relation to the vowel-to-vowel jaw cycle in both time and position-velocity phase-plane domains. In this paper, we examine the additional effects of syllable affiliation and intervening consonant identity. The data show that the upper lip's lowering onset, relative to the position-velocity state of the jaw (phase angle), varied as a function of speaking rate and stress. In addition, the position of the syllable boundary (before or after the intervocalic consonant) and the consonant identity (p vs m) influenced the interarticulator phasing for some subjects. There was a general tendency for any condition that shortened the first vowel in the disyllables to produce an earlier onset of the upper lip relative to the jaw. However, the within-condition jaw cycle duration did not correlate with the within-condition variability in phase. The results are discussed in terms of the relationship between phonetic constraints and articulatory patterning. [Work supported by NIH.]
A comparative study of highway noise barrier design using two different computer models
Authors: Burke Richard E. , Nand Krishna
Published: October 2005

Studies indicate that more people are exposed to noise from motor vehicles than any other source of noise. For this reason, the adverse noise impact of highway noise is of great concern to land use planners, regulatory agencies, and affected communities. To assess the impacts of new highway projects and to identify the effectiveness of mitigation measures, the federal government and some states require that noise analyses be conducted using specific computer models. STAMINA/OPTIMA is the Federal Highway Administration's approved model and is used by many states. SOUND 32 is the California Department of Transportation's preferred model, and is used for highway projects in California. Both models are based on similar mathematical formulations, but differ in vehicle noise emission characteristics, height of noise sources, and attenuation effectiveness for noise walls and earth berms. The purpose of this paper is to report the results of a comparative noise analysis in which both models were applied to an actual highway segment. The influence of traffic volumes, speeds, highway geometry, grade, and receptor distance on the model's estimated noise levels was studied. Differences in the location, dimensions, and effectiveness of barriers recommended by the two models are identified and some of the merits and drawbacks of the models are briefly discussed.