bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamental-frequency approximation methods
Authors: Herman Harry , Kirchner Robert P.
Published: October 2005

The vibration of a sandwich plate is used, as an illustrative problem, to evaluate the effectiveness of some methods of obtaining one-term approximations for the lowest eigenvalue of coupled systems. It is shown that, in using a method of weighted residuals, the boundary conditions satisfied by both the trial and the weighting function play significant roles in the accuracy of the eigenvalue. Moreover, the desired boundary conditions for the weighting function may differ from those of the trial function, so that the Galerkin method, in which the trial function and weighting function coincide, may not be the best method to use. In addition, it is shown that the values of some physical parameters may play a critical role in the accuracy obtained with a given trial function. It is demonstrated that good approximations of the fundamental frequency are obtainable upon uncoupling a set of differential equations, but uncoupling may lead to non-self-adjoint boundary conditions, in which case the weighting function should satisfy boundary conditions which are adjoint to those of the trial function. Attention is also called to a method, due to Lanczos, which does not require a choice of trial or weighting functions, is insensitive to the form in which the problem is stated, appears to require less effort for a given degree of accuracy, and is applicable to non-self-adjoint as well as self-adjoint systems.
Spectrum of rotor noise caused by inlet guide vane wakes
Authors: Hanson Donald B.
Published: October 2005

A blade loading model is formulated for the interaction of an axial-flow fan rotor with turbulent wakes from inlet guide vanes. From this, the spectra of both the blade lift and the associated sound field are computed. The analysis and results arc similar to those in the analogous case treated previously by the author for a stator interacting with the wakes from an upstream rotor [D. B. Hanson, “Unified Analysis of Fan Stator Noise,” J. Acoust. Soc. Am. 54, 1571–1591 (1973)]. The turbulence in the wakes causes a smooth broad-band spectrum component, while the spatially periodic portion of the wakes causes periodic components in the blade lift and sound field. The spectrum peaks do not exhibit bandspreading or “haystacking,” except for fans with inlet guide vane wakes which are wider than the gap between adjacent rotor blades.
Localization of paired sound sources in the rat: small time differences
Authors: Kelly Jack B.
Published: October 2005

Seventeen albino rats were trained to perform two sound-localization tasks with single and paired sound sources. The conditioned suppression of a licking response was used as a behavioral measure. All animals were first trained to detect a change from a series of single clicks on the left to a series on the right. They were then given further training with paired clicks separated by a small time interval; the discrimination was between left-right pairs and right-left pairs. The intervals used were 0.5, 1.0 2.0, 4.0, 8.0, 16.0, 20.0, and 32.0 msec. Five animals were given further tests with smaller values using the method of constant stimuli. Additional values tested were 31, 62, 125, and 250 μsec. Transition from single clicks to paired clicks was good for values between 0.5 and 4.0 msec. An ability to discriminate paired clicks was easily demonstrated for values between 0.25 and 16.0 msec. The upper limit for discrimination was somewhere between 20.0 and 32.0 msec. The lower limit for discrimination was between 31 and 62μsec. These results were discussed in relation to the precedence effect in human hearing.
Discriminations of interaural phase differences
Authors: Yost William A.
Published: October 2005

Listeners were asked to discriminate between two pulsed sinusoids, one presented with an interaural phase delay θ and the other presented with a longer delay θ + Δθ. Frequency of the sinusoids ranged from 250 to 4000 Hz. The difference threshold for Δθ was defined as the dependent variable. This threshold increased as θ increased from zero degrees to half the period of the sinusoid, then decreased as θ was further increased to a full period of the sinusoid. As θ was increased to half the period of the sinusoid, the lateral image appeared to shift away from midline toward the ear leading in time; but as θ was increased beyond half a period of the sinusoid, the lateral image appeared to shift toward the midline from the ear lagging in time. These results were obtained at 250, 500, and 900 Hz. At 2000 Hz, the value of Δθ remained a constant as θ was varied, while at 4000 Hz the lateral image was not moved by any interaural delay. The results imply that (1) for frequencies less than 2000 Hz, lateral discriminations based on interaural phase differences are more acute toward midline than at either side, and (2) for frequencies greater than 2000 Hz, changes in interaural phase are unable to shift the lateral image.
Reply to criticisms by V.E. Callaway of papers MM1 and MM11 at the 86th Meeting of the ASA
Authors: Lane S. R.
Published: October 2005

The data I reported were from slow-response measurements, and EPNL values were derived using appropriate factors (for specific aircraft type, altitude, and operating conditions) determined from large samples of measurements obtained according to the FAR 36 certification method; hence the data were within normal tolerances of ±2 or 3 dB or EPNdB and were not subject to the 8- to 15-EPNdB error suggested by Callaway. My data were consistent with recent data published by other investigators. In regard to passenger cabin noise levels in commercial jet aircraft, measurements by myself and others show that during high-altitude cruise (28 000 to 35 000 feet) passengers near windows and in the mid and rear sections will be exposed to noise levels above 80 dBA.
Localization of strong and weak sounds
Authors: Harkness E. L.
Published: October 2005

A comment is made on J. Blauert's paper: “Localization and the Law of the First Wavefront in the Median Plane” [J. Acoust. Soc. Am. 50, 466 (1971)] from aspects of the localization of strong and weak sounds in the anterior/posterior dimensions of the median plane.
Perceptual structure of 16 prevocalic English consonants sententially embedded
Authors: Mitchell Lilian McGregor , Singh Sadanand
Published: October 2005

This study investigated listeners' utilization of distinctive features in judging phonemic similarity in connected speech in varying noise and quiet conditions. Sixteen initial consonants were presented in monosyllables embedded within a declarative sentence in a position of relative unstress. Five listeners judged 1680 triads in +6 dB, +12 dB, and no-noise conditions each. INDSCAL analysis yielded a five-dimensional solution in the quiet and +12 dB S/N ratio conditions and four-dimensional solution in the +6 dB S/N ratio condition. The features stop/fricative, sibilance, voicing, back/front, and velarity were retrieved in the quiet condition and stop/fricative, sibilance, voicing, and velarity were retrieved in the +12 dB and +6 dB S/N ratio conditions. When masking interfered the weighting of the features changed; sibilance and voicing becoming more prominent in noise while front/back place disappeared. The individual differences of the five subjects resulted two different trends: in average three subjects weighted dimensions stop/fricative, sibilant, back/front, voicing, and velarity in descending order while one of the remaining two subjects weighted voicing maximally and the other weighted velar place maximally. Two conclusions drawn in this experiment were (1) initial consonants, in sentential contexts judged for similarity, produced INDSCAL solutions similar to those found from initial consonants in the context of nonsense syllables; (2) the pattern of variance accounted for by similar INDSCAL dimensions varies with signal-to-noise ratio.
Diffraction of evanescent waves, with applications to aerodynamically scattered sound and radiation from unbaffled plates
Authors: Chandiramani K. L.
Published: October 2005

We discuss a slight modification of the classical problem of diffraction of acoustic waves off a semi-infinite, thin, rigid surface. The modification is: the waves incident on the surface are evanescent rather than freely propagating. The solution for the diffracted sound wave in the farfield, and some variations on this solution, are considered with reference to the following problems: (1) sound diffracted by a turbulent boundary layer flow off the sharp edge of a large hard surface; (2) for a large plate undergoing flexural vibration, radiation efficiencies associated with unbaffled plate edges of different boundary conditions.
Horizontal ray theory for ocean acoustics
Authors: Weinberg Henry , Burridge Robert
Published: October 2005

The solution of the reduced scalar wave equation for an almost stratified medium is written in the form of an asymptotic power series. The vertical structure of the solution is expressed as a linear combination of the normal-mode eigenfunctions whose coefficients satisfy two-dimensional eikonal and transport equations. Although smooth caustics may be treated for the two-dimensional scalar wave equation, the problem of a uniform approximation near a point source has not yet been resolved. Finally, the theory is applied to acoustic propagation in a realistic model ocean and the results are compared with measurements.
Nonlinear effects in biodynamics
Authors: Skalak Richard
Published: October 2005

Biological systems are often characterized by large deformations, nonlinear constitutive equations and complex arrangements of soft tissues, bone, and fluids. Linear analysis usually provides at least a rough description which is sufficient for many purposes, but nonlinear theory is often required for accurate description. Wave propagation in blood flow is definitely a nonlinear phenomenon but may be linearized for many applications. In the arteries, the nonlinearity is less significant than in veins which distort severely. The “pistol shot” effect requires nonlinearity. In shock and vibration of the entire body or large parts of it, nonlinear wave propagation and vibration are significant. In recent work on seat ejection problems, the spine is represented by nonlinear beam theory. In head injury due to impact, most theoretical treatments to date use linearized elastic and acoustic theory. At fracture and physiologic damage levels, nonlinear properties and dynamics are important but not yet analyzed extensively.
Second-order stress distributions in a long orthotropic bar excited into free longitudinal vibration
Authors: Zuckerwar Allan J.
Published: October 2005

A perturbation technique described recently [A.J. Zuckerwar, J. Acoust. Soc. Am. 54, 699–711 (1973)] is applied to find the exact second-order stress distributions of a long orthotropic bar excited into free longitudinal vibration. The stresses are related to homogeneous and nonhomogeneous potential functions. The homogeneous potential function may be described by one of three analytical expressions, depending upon whether the following combination of elastic compliances is less than, greater than, or equal to unity: A = (s11s33 − s132) (s22s33 − s232)/[(s12s33 − s13s23) + 12s33s66]2. Results are presented for a single crystalline specimen of potassium chloride, representative of the first of the above cases (A < 1).
Application of acoustic microscopy to the study of embryonic development
Authors: Ahmed M. , Kessler L. W.
Published: October 2005

A preliminary investigation was conducted to determine the acoustically revealed details of embryonic tissue. A fixed, but unstained 72-hour chick embryo specimen was imaged at an acoustic frequency of 100 MHz with the scanning laser acoustic microscope [L.W. Kessler, P.R. Palermo, and A. Korpel, Nature 232, 110 (1971)]. The acoustic micrographs obtained, which exhibited a resolution of 20 μm, revealed many organ formations and regions of cell condensation within the embryo. In order to minimize the alterations to the tissue structures, histological staining techniques were not employed. Consequently, the optical opacity of the specimen precluded our obtaining a useful optical image for comparative purposes. This paper will discuss the comparison between the structures revealed in the acoustic microscope and the established microanatomy of the embryo. It will also be shown that the selective interaction of sound with the different tissue structures in the embryo may be considered to be analogous to a hypothetical new staining technique.
Auditory nonlinearity: audible subjective difference tones fh − f1 and 2f1 − fh
Authors: Erdreich J. , Clack T. D.
Published: October 2005

The polynomial nonlinearity hypothesis of the previous paper equates growth rates of equal-order difference and summation tones. Growth rates for 2f1 − fh and possibly fh − f1(fh/f1 = 1.2;f1 = 1000 Hz) have been found to approximate 1 dB/dB, contradicting the classical nonlinear hypothesis. At least three possible explanations of these discrepancies exist. Only one method, cancellation [E. Zwieker, Acustica 5, 67–74 (1955)], has been used previously, suggesting a possible methodological artifact. Agreement between the psychoacoustic results and some of the physiological data suggests possible real disparities between the generation of audible and inaudible subjective tones. Finally, these difference tones may be processed in some special manner after their generation. To explore the first possibility, a new method was developed incorporating alternating binaural loudness balances between the subjective tone and a contralateral pure tone of equal frequency under conditions of equivalent masking. Cancellation estimates corrected for masking (a correction not previously incorporated) agree closely with loudness balance measures of 2f1 − fh from the same subjects. Both methods produced 1 dB/dB growth functions, an unlikely result if the discrepancies were methodological. Grewth and audibility of these subjective tones suggest a difference in processing after generation to account for the discrepancies.
Evaluation of pitch-strength predictions of the pattern-transformation model of pitch
Authors: Wightman Frederic L.
Published: October 2005

The pattern-transformation model of pitch perception [Wightman, J. Acoust. Soc. Am. 54, 407–416 (1973)] can successfully predict the pitch of many types of complex-tone stimuli. In addition, the model provides numerical estimates of pitch “strength.” In order to test these latter predictions we assumed that performance in a musical interval-recognition paradigm [Houtsma and Goldstein, J. Acoust. Soc. Am. 51, 520–529 (1972)] is a direct indicator of pitch strength; the better the performance, the stronger the pitch. Thus, Houtsma and Goldstein's data can be used to evaluate the pitch-strength predictions of the model To do this, a set of stimuli was defined such that all stimuli in the set led to the same level of performance in the interval-recognition paradigm; the stimuli lay on one of Houtsma and Goldstein's “constant-performance contours.” Then pitch-strength predictions were generated for these stimuli. If our assumption is valid, all the stimuli should have the same predicted pitch strength. Except for stimuli of low fundamental frequencies, the predictions follow this pattern. The failure with low-fundamental stimuli seems to be a result of our initial assumption that spectral resolution (critical bandwidth) is a constant percentage of frequency (i. e., that the peripheral analyzer has constant Q). If the constant Q assumption is relaxed, so that our assumed critical bandwidths agree more closely with available data, the performance of the model is much improved.
Model for pitch perception
Authors: Thomas Ian B. , Ravindran A.
Published: October 2005

The three important stages in pitch perception are (1) acoustic to mechanical transformation, (2) mechanical to neural changes, and (3) neural firings to perception. The developed model incorporates all three of these stages for explaining pitch perception. Flanagan's transfer function (based on Békésy's experiments) relating the basilar membrane displacement to stapes movement is used for obtaining the waveform of displacement at the attended region of the basilar membrane for a given stimulus. The axis crossing intervals of this band-pass-filtered stimulus (not those of the stimulus external to the ear) are encoded in terms of intense and sparse firings, since only unidirectional movement causes appreciable neural activity. According to the model, these individual axis crossing intervals are stored and compared successively. Whenever adjacent intervals differ by 10 or more μsec, it is presumed that a second-order neuron is activated at a higher level to mark the time of occurrence. The model proposes that various combinations of time intervals between these higher-order firings give the reciprocal of different pitches associated with the stimulus. This model predicts the pitch of the so-called “difference” tones, residue, and cubic difference tones without calling for any nonlinear mechanism. [Work supported by NIH.]
Pitch of noise plus noise delayed
Authors: Thomas Ian B. , Bostwich Richard D. , Ravindran A.
Published: October 2005

Rosenberg has demonstrated [J. Acoust. Soc. Am. 47, 118 (1970)] that if white noise is added to itself delayed by time T, the composite stimulus gives rise to a perceived pitch equal to the reciprocal of T. Clearly, this experiment raises problems for place theorists, since the spectrum of the composite stimulus is also “white.” Rosenberg's results raise no less of a problem for those who propose periodicity in the stimulus waveform as the determinant of pitch. This stimulus has neither periodicity nor concentrations of spectral energy of any kind. We have applied the theory of pitch perception presented by Ravindran and Thomas at this meeting to this stimulus as follows. The stimulus waveform was generated with the aid of a computer for delay times of 1 and 2 msec. This signal was made available through D/A conversion for monitoring and recording and for input to an analog device whose output represents the waveform of basilar membrane displacement for various membrane locations and for two possible middle-ear transfer functions. The resulting signal was then further analyzed using the steps called for in the Ravindran and Thomas model. The result for any given delay is a “distribution of perceived pitches” which has a distinct maximum at the appropriate pitch (1/T). Changes in membrane location and in middle-ear characteristics have minor effects on the distribution and do not alter the frequency of its maximum. These results lend support to the proposed model. [Work supported by NIH.]
Sideways look at dichotic listening
Authors: Goldstein Louis , Lackner James R.
Published: October 2005

The present experiment investigates the possibility that performance on the dichotic listening task is systematically influenced by variables unrelated to the linguistic or auditory character of the stimuli employed. Subjects sat in a lighted room with head position fixed and listened to a standard dichotic CV tape. Binocular Risley prisms were used to displace the subjects' visual environment either 13° to the left, 13° to the right, or not at all. A right ear advantage was obtained in the no-displacement condition (percentage of correct responses contributed by the right ear—POC—was 55.5%). This advantage was decreased in the left-displacement condition (POC = 51.8%) and was increased in the right-displacement condition (POC = 57.1%). This result indicates that subjects' performance on the dichotic listening task may reflect a number of psychological and physiological factors, in addition to a possible cortical hemispheric specialization for language. Among the factors considered are attention (of an involuntary sort) and spatial orientation mechanisms normally involved in sound localization and binaural fusion.
Dichotic perception of initial consonants and lexical tone in Cantonese
Authors: Smith Timothy S. , Shand Michael
Published: October 2005

At a previous meeting of the Society (November 1972) we reported an inability to detect an ear advantage in the dichotic perception of lexical tone for speakers of Cantonese. This negative result may have arisen from a possible nonlinguistic response mode used in that study, as well as the overall high level of performance in the task for Cantonese speakers. In the present dichotic experiment, native speakers of Cantonese heard six meaningful CVC words which differed only in initial consonant, six CVC words differing only in lexical tone, and the same set of six tone words presented at an S/N ratio of − 10 dB. They responded by pressing buttons labeled with the appropriate Chinese characters. Preliminary analysis of the results shows that the tone words at the normal S/N ratio (40 dB) did not show a significant ear effect, while both the consonants and the tones at − 10 dB showed unidirectional ear effects. Non-Cantonese speakers in a control group showed a right-ear advantage for the consonants and a left-ear advantage for the tones at the normal S/N ratio.
Dichotic testing of split brain subjects
Authors: Springer Sally P.
Published: October 2005

Four subjects with different portions of the cerebral commissures sectioned were tested with a consonant-vowel dichotic listening task. Subjects reponded in each of the following conditions by encircling the item or items heard on a paper listing all the possible syllables: standard dichotic presentation, dichotic presentation with selective attention instructions to attend to the nondominant ear, and monotic presentation of single syllables. Three of the four subjects showed almost complete extinction of the nondominant ear inputs with dichotic presentation, even under the selective attention condition. The fourth subject performed similarly to neurologically intact controls. The data are discussed in terms of the monotic data for each subject and the portion of the cerebral commissures sectioned, and the findings are evaluated in terms of their implications regarding the status of the nondominant hemisphere as a processor of speech.
Developmental dysphasia: a defect of perception, not language?
Authors: Tallal Paula
Published: October 2005

Developmental dysphasia may result from a primary impairment in the rate of processing acoustic stimuli, regardless of whether stimuli are verbal or nonverbal. Subjects were tested for their ability to perceive binary sequences of (1) complex tones, (2) synthesized steady-state vowels, (3) synthesized stop-consonants with formant transitions of normal duration (43 msec), and (4) synthesized stop-consonants with formant transitions extended in duration (95 msec). With nonverbal stimuli, dysphasics were adversely affected by decreases in duration of stimulus elements and interval between elements, and by increases in total number of elements. Total duration of stimulus patterns proved critical to dysphasics' performance. With verbal stimuli, dysphasics proved unimpaired in their discrimination of steady-state vowels, but grossly impaired in their discrimination of stop-consonants comprising a 43-msec transitional period. However, when the transitional period of the same stop-consonants was extended to 95 msec, the dysphasics performed as well as normals. It is suggested that developmental dysphasia is not a language disorder, but results from failure to develop a nonverbal auditory perceptual process which is necessary for speech perception.
Use of graphic level recorders as indicating instruments. II. Performance in environmental noise measurements
Authors: Farinacci J. W. , Webster W. J.
Published: October 2005

In the course of investigating the ability of graphic level recorders to meet the “fast” and “slow” sound level meter characteristics (ANSI S1.4-1971), some differences were noted between the response of a level recorder and sound level meter known to fulfill the same indicating instrument specification. This occurrence may be attributed to the basic differences in operating principles of the instruments involved, and apparently can exist within the definition of the sound level meter. To obtain an estimate of the differences which may be encountered in practical environmental noise measurements, direct comparisons between a sound level meter and graphic level recorder were made for four situations: nearly constant ambient noise, construction noise, truck passbys at 50 ft, and a pile driver. These sounds were chosen to provide progressively more challenging demands on the response of the instruments to fluctuating sound levels. In each case, the sound level meter is assumed to provide the “correct” reading as it is the instrument specified for the enforcement of most environmental noise regulations.
DNA degradation by acoustic microstreaming
Authors: Williams A. R.
Published: October 2005

Calf thymus DNA in saline buffer (SSC) was irreversibly degraded by the acoustic microstreaming field generated around submerged portions of a transversely oscillating steel wire. Free radical scavenging agents (e.g., I131) were firmly (covalently?) bound to sheared fragments, strongly indicating covalent bond rupture during cleavage of the DNA backbone. All molecular weight estimations were made by viscometry under “zero-shear” conditions and showed that DNA of initial average molecular weight 9.34 × 106 daltons was not degraded until the wire displacement amplitude exceeded 18 μm. At any given amplitude above this threshold, the measured molecular weight decreased asymptotically with time of exposure and was usually within 5% of its limiting value after 5 min. Each original average molecule was halved after 5 min shear at 28 μm and quartered at a displacement amplitude of 59 μm. Approximate lower limits were estimated for the velocity gradients existing near the wedge-shaped wire trip; this gave a critical shear rate of about 105 sec−1 to cleave each original DNA molecule, and an average breeding force of about 5 × 10−5 dyn.
An auditory illusion
Authors: Deutsch Diana
Published: October 2005

Listeners were presented with a sequence of sinusoidal tones, each tone 250 msec in duration and with no gap between adjacent tones. All tones were either 400 or 800 Hz, and these frequencies were presented in strict alternation. This sequence of alternating tones presented at equal amplitude to both ears simultaneously for 20 sec. However, when one ear received 800 Hz, the other received 400 Hz and vice versa. Under these conditions 48% of 42 right-handed listeners perceived a single tone oscillating from ear to ear whose pitch also oscillated from one octave to the other in synchrony with the localization shift and with the higher pitch localized in the right ear. When the identical sequence was again presented but with earphones reversed, these listeners reported the identical percept with the higher pitch still localized in the right ear. Two listeners with absolute pitch identified the alternating pitches as G4 (392 Hz) and G5 (784 Hz). Another 14% of the listeners obtained the same illusion but with the high pitch consistently localized in the left ear. The remaining 38% reported a variety of percepts, but no listener perceived the stimulus correctly. A similar illusion also occurs with two frequencies arbitrarily chosen from within this octave range.
Acoustic analyses of low-risk lies
Authors: McGlone Robert E. , Petrie Charles R. , Frye Jerry
Published: October 2005

Studies have attempted to differentiate lies from truth based on analysis of the acoustic signal. Some reports suggest that such procedures are successful even for “yes-no” responses to questions where no penalties for lying or rewards for truth are imposed. In this study, such a low-risk situation was created. Twenty-one female speakers were asked individually to select a number from 1 to 4. They were instructed to respond “no” each time when asked if it were number 1, 2, 3, or 4. Their answers were recorded and the number they selected (where the low-risk lie occurred) also was noted. Responses were subjected to spectrographic analysis for measures of frequency and duration, through a graphic level recorder for relative intensity and through a PSE-1 for pattern matching. None of these measures provided better than chance identification of the lie response. Results suggest either that sufficient information was not available in the “low-risk” lie situation or the methods of analysis used were not adequate to isolate the cues present in the signal.
Automatic isolation and analysis of nasals and nasalized vowels in continuous speech
Authors: Gillmann R. A. , Ritea H. B.
Published: October 2005

Nasals and nasalized vowels comprise approximately 14% of the phonemes used in English Speech. An algorithm is described for locating and identifying nasals and preceding nasalized vowels. Spectral analysis is performed on a computer using a linear prediction model containing both poles and zeros, to locate the formants and antiformants of these phones. The effectiveness of this approach is compared to that of an all pole (LPC) model, using formant bandwidth data to locate the antiformant. The identification of nasalized vowels is based on the hypothesis that the formants of an unnasalized vowel, when nasalized, tend to move away from the antiformant of a succeeding nasal. Experimentation has indicated that (1) automatic techniques can be employed to isolate nasals and preceding nasalized vowels in continuous speech; (2) linear prediction can be used to effectively analyze the spectra of these phones; and (3) speaker-dependent tables of formants and antiformants extend these results to multiple speaker environments.
Automatic stress contour extraction from continuous speech
Authors: Sargent D. C. , Li K. P. , Fu K. S.
Published: October 2005

An automatic stress extraction algorithm was developed capable of producing a three-level stress contour (stressed, unstressed, and reduced) from continuous speech sentences. Operation of the algorithm began with the partial identification of those stress levels whose values were apparent from measurements of the change in F0 and energy integral within the syllable. Additional stress recognition was based on comparative stress judgments obtained from consideration of the differences between average F0 and energy integral data from adjacent syllables. Metric criteria were also applied to determine the most likely stress level for those syllables whose value could not be reliably obtained from their acoustic correlates, and to recognize obvious rhythmic violations in the predicted stress contour. Results are presented comparing the stress recognition available from an algorithm using only the acoustic correlates within the syllable, versus one which also applies the comparative stress and metric considerations outlined above.
Disk parametric acoustic array
Authors: Lockwood James C.
Published: October 2005

A parametric acoustic array, the primary field of which is a thin disk of waves spreading cylindrically between two parallel planes, is analyzed. It is shown that the half-power beamwidth of difference-frequency radiation perpendicular to the disk exceeds the beamwidth of the corresponding collimated plane wave parametric array by a factor of 1. 316. The radiated intensity is less than in the plane-wave case by a factor of α0/k, for the same total acoustic power in the primary waves, where α0 is the absorption coefficient at the mean primary frequency and k is the wavenumber at the difference frequency.
Performance of a parametric receiving array in the presence of a strong, distributed nearfield interference
Authors: Kowalczyk Robert E.
Published: October 2005

A potential problem of a parametric receiving array mounted on a mobile platform is the platform's radiated noise interference. This can severely limit the detection performance of the parametric receiving array and, hence, can possibly limit the parametric receiving array to a quiet (stationary) platform. On the other hand, inspection of the nearfield interference pattern of a distributed set of discrete radiators along the boundaries of typical platform geometries suggests the possibility of nulls in the parametric receiver response over a narrowband range of frequencies. The potential of operating the parametric receiving array through these nulls is explored.
Multi-sensor geometry for Doppler tracking
Authors: Friedman A. J. , Spooner R. L.
Published: October 2005

In the field of acoustic Doppler tracking, the sensitivity of source parameters to the geometrical configuration of the sensor field has been the subject of numerous computer simulation investigations. In the present study, the matrix equation which defines the linearized sensitivity has been analyzed for a symmetric sensor field and the necessary matrix inversion has been achieved in closed form. Expressions for the source parameter variances have been obtained and evaluated for optimum performance configurations. The geometrical parameters which govern performance are shown to be the angular positions of the sensors with respect to the source track, i.e., the geometrical position of the sensors on the source Doppler profile. Performance is shown analytically to increase as the amount of the Doppler profile sampled by the sensor pattern increases, and this quantifies previous simulation trends. The study results provide the foundation for development of robust geometrical sensor configurations for operational use.
Directivity as a discriminant in monitoring of air-acoustic environmental noise
Authors: Harris B. , Lange G. P. , Torok S. F.
Published: October 2005

Directivity is useful in the automatic monitoring of air-acoustic environmental noise because discrimination is possible not only between ground and airborne sources, but between different ground sources as wall. The experimental program compared omnidirectionals, gradients, cardioids, donuts, cardonuts, and second-order donuts as vertical discriminators between ground and airborne sources. DIFAR, DARAS, and CODAR arrays were the means examined for resolving ground sources. The data were gathered in flat, sandy, scrub-pine woods (New Jersey) and under a 50-ft jungle canopy (Panama). Nineteen different microphones were mounted at zero, 10- and 40-ft heights. Each height contained an omnidirectional, downward-looking cardioid and pair of horizontally crossed gradients. The 10-ft level included separate DIFAR, 2-ft baseline DARAS, and 75-ft CEDAR arrays. Vertical directivity discriminated between ground and airborne sources provided the microphone pattern nulled both upward and downward to attenuate the multipath. Cardonuts and second-order donuts were most effective, flyover noise being reduced 25 dB even in the presence of severe ground reflectivity. DIFAR and DARAS gave bearing angles to vehicles consistently within a few degrees in spite of the multipath. CODAR was not useful. Adaptive DIFAR enhanced capability by improving or rejecting bad bearings.
Effects of blast waves on biological structures
Authors: Oestreicher Hans L.
Published: October 2005

The effects of blast waves passing over a living organism (human or animal body) are not different in principle from those on inanimate structures. Although the immediately visible effects are functional disorders, injury, or death of the organism, the ultimate causes of these effects are certain mechanical processes—primarily severe changes of volume and large relative displacements of adjacent parts of the body. In order to obtain a quantitative understanding and assessment of the effects of a shock wave upon a living system, the organism is considered as an elastic fluid-mechanical system, and the interaction of this system with the blast wave is discussed. By correlating specific mechanical fluid-dynamic processes to effects observed in experiments and accidental blast waves, this leads to a unified explanation and analysis of shock wave effects upon biological structures.
Transient response analysis of complex submerged structures
Authors: Geers Thomas L.
Published: October 2005

Through the continuing development of discrete element methods of structural analysis, great progress has been made during the past decade in the static and dynamic analysis of complex structures. The transient response analysis of such structures submerged in a dense fluid, however, is severely complicated by the intrusion of important fluid-structure interaction effects. Following a brief review of the nature of these effects, a variety of techniques for the treatment of the fluid-structure interaction are examined. Specifically, standing wave (modal), traveling wave, brute-force numerical, modified numerical, retarded potential, and surface interaction approximation techniques are discussed. The characteristics of each of these techniques are studied and the compatibility of each with present discrete element methods of structural analysis is assessed.
Damped oscillatory excitation as a rational simulation of pyrotechnically induced environments
Authors: Prasthofer P. H. , Nelson D. B.
Published: October 2005

A great deal of attention has been focused in recent years on the development of realistic shock simulation techniques. Controversy has arisen over the traditional use of the shock response spectrum versus the techniques of Fourier analysis to describe shock severity and to synthesize realistic waveforms. The authors propose a superposition of decaying oscillatory functions as being a natural simulation of farfield vibrational excitation of a structure caused by a short-duration shock input. A discussion is presented of the classical descriptors of shock severity and their application to multi-degree-of-freedom systems. Structures are shown to respond naturally in the form of a superposition of decaying oscillatory waveforms when subjected to an impulsive input. The relationship of these oscillatory functions to the shock descriptors is discussed. Bounds are derived on the energy of the response as well as the peak response of a structure when the input waveforms are properly selected.
Electronic amplification in the theater
Authors: Klepper David L.
Published: October 2005

Broadway theater has progressed from occasional use of amplification to consistent use. Reinforcement in the Broadway theater has and is being used to improve speech clarity, to bring singers' voices up over the loud levels produced by pit orchestras, and to change the balance between individual singer's or actor's voices. It is increasingly used to change orchestral balances and to produce a kind of sound that show composers and arrangers are familiar with in recording studios. The equipment used for such purposes varies from simple to complex, depending upon the show and the theater. The argument between those preferring loudspeakers on each side of the stage and those preferring central loudspeaker clusters over the stage continues, as does the argument between those recommending installed systems for theater and those preferring rental systems touring with individual shows. Meanwhile, the use of electronic sound amplification as standard practice has permitted architects and theater designers to leave the conventional proscenium theater form behind and experiment with new shapes, such as thrust-stage theater and theater-in-the-round. Electronic sound amplification systems designed for such spaces usually employ a combination of distributed and central loudspeaker system design, often with time-delay systems.
New developments in high fidelity
Authors: Hirsch Julian D.
Published: October 2005

The features and performance of current home high-fidelity products will be described and compared. The evolution of modern electronic and electro-acoustic audio components is related to technological developments and consumer pressures. The audible or practical significance of various features and performance parameters is also discussed. The status of four-channel sound is reviewed. Some probable trends in future equipment designs are considered.
Design, construction, and performance of full-range Walsh-type omnidirectional, coherent loudspeakers
Authors: Gersten M.
Published: October 2005

The basic design considerations for very high-power, full-range electrodynamic motor structures and terminated transmission line cones are outlined. Certain novel materials and techniques used in the construction of these assemblies are described and demonstrated with photographs and cutaway components. Results of propagation velocity, frequency amplitude, dispersion, and impulse measurements are shown. The measured performance of the Walsh-type loudspeaker is compared with the other major types of wide-range reproducers. The superiority of the Walsh device in waveform retention and coherent wavefront synthesis is demonstrated. The use of the Walsh coherent-sound loudspeaker in applications requiring very accurate acoustic waveform generation in both audio and ultrasonics is discussed.
Overview of some recent experiments on pure-tone intensity discrimination
Authors: Rabinowitz W. M. , Haughey P. J. , Johnston R. C. , Braida L. D.
Published: October 2005

Intensity resolution for 0.5-see bursts of 1000-Hz tones has been measured in quiet as a function of intensity increment for a variety of intensities ranging from absolute threshold to 90 dB SPL using a symmetric 2I-2AFC technique. The results indicate that (1) in the vicinity of absolute threshold, the discriminability of two intensities can be simply predicted from measures of their detectability; (2) resolution per decibel increases with intensity in the range 0–15 dB SL and may attain a local maximum at 15 dB SL; (3) Weber's law appears to be valid only from about 20 to 40 dB SL; (4) at higher intensities, resolution per decibel improves systematically with intensity; and (5) at each intensity, d′(I, I + ΔI) is proportional to log[(I + ΔI)/I] for values of d′ between 0.5 and 2.5. This talk attempts to relate these findings quantitatively to a variety of relevant prior work.
Suppression of forward masking
Authors: Shannon Robert V.
Published: October 2005

Consider a forward-masking task in which the subject is trying to detect a brief sinusoidal signal (20 msec) following a masker (500-msec duration) of the same frequency. Under certain conditions the signal is easier to hear when another sinusoid is added to the masker. This reduction in the effectiveness of the original masker by the addition of a second tone will be called suppression. This phenomenon was found only in forward masking. The forward-masked threshold of the signal was measured as a function of the frequency of the added tone, called Fv. Suppression of the masked threshold of the signal was observed when Fv was 10%–20% above the signal frequency. The threshold of the signal was lowered by 7 dB when the intensity of Fv was increased from the same intensity as the signal frequency in the masker to 30 dB above that intensity. The results look similar to two-tone inhibition data collected on first-order auditory neurons. [This research was supported by a grant from the National Science Foundation and by a research grant awarded to the Center for Human Information processing.]
Symmetry properties of binaural masked detection thresholds with respect to the dependence on interaural time delay and interaural amplitude ratio of the masker
Authors: Colburn H. S. , Latimer J. S.
Published: October 2005

Thresholds for a 500-Hz tone masked by broad-band random noise were measured for conditions that simultaneously include differences in the interaural amplitude ratio and in the interaural time delay of the masking noise. The interaural amplitude ratio of the target was always equal to the interaural amplitude ratio of the masker, and the interaural phase of the target always differed by 180° from the interaural phase of the masker. Measurements include interaural time delays of both polarities for each of five amplitude ratios between 0 and 40 dB. The time delay values were ±200 μsec, ± 500 μsec, and ± 800 μsec. The thresholds for positive and negative values of delays do not differ more than experimental error for any amplitude ratio. It is argued that this symmetry in detection performance, with respect to the sign of the delay, is unexpected in light of the asymmetry observed in interaural time discrimination results [Domnitz, J. Acoust. Soc. Am. 53, 1549–1552 (1972)] and that the results of these two experiments may have important implications for the interaction of time delay and amplitude ratio in binaural hearing models.
Performance of an electrical-analog model of the auditory system in several masking conditions
Authors: Dolan Terrence R. , Hirsh I. Richard , Tangney John
Published: October 2005

The present paper includes a description of an electrical-analog model of the monaural and binaural system and an evaluation of its performance in a variety of masking conditions. Each monaural channel of the model is similar to that described by Jeffress [J. Acoust. Soc. Am. 41, 2 (1967); 44, 1 (1968)] and consists of a narrow filter, half-wave rectifier, and leaky-integrator network prior to a decision device. The binaural channel receives inputs from each monaural channel and consists of a subtractor network and full-wave rectifier prior to a decision device. Although the binaural processor is borrowed conceptually from Durlach's equalization-cancellation model [J. Acoust. Soc. Am. 32 (1960); 35 (1963)], the binaural mechanism operates on the outputs of the monaural channels rather than the input waveforms. Data gathered in masking experiments which have manipulated such signal parameters as intensity, duration, interaural phase, and interaural intensity are compared to the model's performance in identical situations.
Fast field program (FFP)
Authors: DiNapoli F. R. , Marsh H. W.
Published: October 2005

The archetype model of a stratified ocean leads to an integral (Hankel) transform representation of the underwater sound field of a simple source. For numerical work, the asymptotic (ray) method or a residue (normal mode) series have been widely used to approximate this transform. Both have mathematical limitations, and being eigenvalue problems, can present significant computational difficulties. Current computer technology now permits direct numerical evaluation of the transform. We accomplish this using a fast Fourier transform (whence the title). Development of this technique was initiated in 1967 under the sponsorship of the Acoustics Programs, Office of Naval Research. We have employed it over a wide range of the various parameters involved, and it is now in routine use at our laboratory. Its speed and accuracy make it a viable candidate for large-scale calculations or for use on naval vehicles with limited computer facilities.