bluuebunny/crossref_metadata_2025 huggingface dataset:
Harmful jet noise at schools and residences near Los Angeles International Airport seven years later
Authors: Lane Sam R.
Published: October 2005

A study of excessive noise at schools due to commercial jet aircraft approaching Los Angeles International Airport was reported at the November 1973 ASA meeting in Los Angeles. The results indicated that school children were exposed to maximum aircraft noise levels often greater than 115 dBA, which exceeds established limits for serious adverse effects on health and hearing. Subsequent to 1973, the EPA (region IX) conducted 24-h noise monitoring on several days for two successive years at Felton School, where the highest noise levels occur. More recent measurements (1980) have also been obtained. Important questions that arise include: (1) Have the jet aircraft noise levels changed since 1973? and (2) Are the school children and area residents still exposed to harmful noise levels? This paper presents a summary of the ensuing studies and a comparison of the results. [Work not supported by any government agency.]
A vector-potential approach to radiation from force-like sources
Authors: Hadden W. James
Published: October 2005

This paper presents an extension of the previously reported analysis of sound radiated by a moving point force, in which the acoustic pressure is represented as the divergence of a vector potential function. A single relationship between the particle velocity and the potential is obtained from the continuity equation. This relationship is employed in the construction of the pressure field above a surface with finite acoustic impedance. Applications to predictions of helicopter rotor noise and to flow noise are discussed.
Differential sound absorption technique and unsymmetrical ion pairing in MgSO4 + NaCl solutions
Authors: Hsu Cheng-chih , Fisher Frederick H.
Published: October 2005

Sound absorption reduction in 0.02 M MgSO4 solutions with the addition of NaCl has been measured at 25°C and 1 atm, using a 100-liter titanium spherical resonator. Using the equation Kurtze and Tamm [Acustica 3, 33 (1953)] developed, a/a0 = [MgSO4]/(MgSO4] + F[NaCl]), our measured results for concentration ratios of [NaCl]/[MgSO4] = 0, 1, 2, 4, and 6 yields F = 0.146 ± 0.033, contrary to Kurtze and Tamm's value, 0.21. Our value of F agrees well with the 0.134 value from theoretical calculations including effects of ionic strength and ion-pairing of MgSO4, NaSO4−, and MgCl+, using dissociation constants of 0.0062, 0.1, and 0.178, respectively, for these salts. Theory also shows that F is not a constant, but a variable depending on [MgSO4] and [NaCl]/[MgSO4]. If the dissociation constants of the unsymmetrical salts are doubled, F = 0.093. F is 0.052 if only ionic strength effects are included, i.e., no unsymmetrical ion-pairing. This technique therefore can be used to quantitatively study ion-pairing of unsymmetrical salts. [Work supported by ONR and NSF.]
Temperature and impurity dependence of the vibrational collision number for O2−H2, O2−He, and O2−CO2 systems between 300°–675°K
Authors: Feng I-an , Lee M. C.
Published: October 2005

The oxygen vibrational collision number for three binary systems (O2−H2, O2−He, and O2−CO2) has been measured between 300°–675°K at low impurity concentration using an acoustic resonant technique. For the pure oxygen case extrapolated from the O2−He system, for instance, the experimental vibrational collision numbers follow closely the curve derived from the Parker's theory [J. G. Parker, J. Chem. Phys. 34, 1763 (1961)] and high temperature (> 1700°K) shock tube data [R. G. Millikan and D. R. White, J. Chem. Phys. 39, 3209 (1963)]. However, our experimental data disagree strongly with the shock tube data trend below 1700°K. The experimental vibrational collision numbers for the binary systems have been found in good agreement with Parker's theoretical prediction. A new data analysis technique has been developed to sort out the ever-elusive background loss in the resonant chamber resulting in a more reliable number for the molecular absorption at low impurity concentrations. [Work supported by NASA under Contract Number NAS7-100.]
Broadband optical interferometer for monitoring Rayleigh waves
Authors: Claus Richard O. , Cantrell John H.
Published: October 2005

A wideband differential interferometer has been developed to detect ultrasonic surface wave pulses. The interferometer combines the advantages of wideband Michelson techniques with those of similar narrowband differential methods used to measure cw ultrasonic waves [C. H. Palmer, J. Acoust. Soc. Am. 53, 948 (1973); D. P. Jablonowski, Appl, Opt. 17, 2064 (1978)]. In our system, two coherent light beams are focused on the surface supporting the pulsed waves. The reflected beams are combined interferometrically, filtered, and detected using a broadband optical receiver. Receiver output is proportional to the difference between the normal components of surface particle displacement at the location of the two beams. If an acoustic pulse arrives at one beam focus at time t1 and at the other at t2 = t1 + Δt, output signal bandwidth during Δt is limited only by detector response. For t > t2, bandwidth is determined by the differential acoustic sensitivity which may be adjusted by altering beam separation. Sensitivity calibration for a nominal 1-MHz bandwidth and measurements of pulses on a 0.3 cm thick 7070 Pyrex plate are presented.
A unified picture of plane wave reflectivity from a liquid-solid interface and a solid plate in a liquid
Authors: Ngoc T. D. K. , Mayer W. G. , Claeys J. M. , Leroy O. J.
Published: October 2005

The ultrasonic plane wave reflection coefficient for a solid plate immersed in a liquid must be reducible to that for a liquid-solid interface as the solid plate thickness becomes very large. This can be achieved when absorption is taken into account. The calculated results describe the reflectivity characteristics of a thick solid plate and provide practical criteria to determine the lower limit of the solid sample thickness that can be considered as a half-space. [This work was supported by the Office of Naval Research, U.S. Navy, and the Scientific Affairs Division, NATO.]
High-frequency sound propagation in a moving medium
Authors: Cho Y. C. , Rice E. J.
Published: October 2005

An equation determining the sound ray path in a spatially varying mean flow [L. D. Landau and E. M. Lifshitz, Fluid Mechanics (Addison-Wesley, Cambridge, MA, 1959) is examined and expanded to study a high-frequency sound propagation in both potential and rotational mean flows. The study includes the high-frequency sound refraction through a shear layer of finite thickness.
Sound attenuation in a liquid-filled rectangular duct lined with a viscoelastic material in the presence of a uniform flow
Authors: Cho Sung-Hwan Ko , Ho Louis T.
Published: October 2005

A two-dimensional theoretical study has been made of the sound attenuation in a liquid-filled rectangular duct internally lined with a viscoelastic material. In the theoretical analysis, it is assumed that the rectangular duct is rigid, and the viscoelastic liner is an isotropic elastic medium. The viscoelastic liner is a rubber-like material that has a loss factor associated with the shear modulus. The liner is in perfect contact with the duct wall. The fluid in the lined duct is characterized by the medium density and the speed of sound in the medium. The viscoelastic liner is characterized by Lamé constants which can be expressed in terms of any two of the following quantities; Young's modulus, bulk modulus, and Poisson's ratio. The deviation of the eigenvalue equation was based on the theory of elasticity, the acoustic wave equation in the presence of a uniform flow, and the standard boundary conditions. The eigenvalue equation has been solved numerically, and the sound attenuation was obtained using the calculated eigenvalues.
More on the binaural edge pitch
Authors: Hartmann W. M. , Hartmann M. A.
Published: October 2005

The binaural edge pitch is created by dichotic, broadband noise with an interaural phase spectrum which changes abruptly. [M. A. Klein and W. M. Hartmann, J. Acoust. Sec. Am. Suppl. 1 67, S20 (1980)]. We employed dichotic noise with Fourier components in phase below frequency f0 and out of phase above f0. The pitch of this noise corresponds to a frequency which is about 4% above or below f0 for 250 < f0 < 1000 Hz. For f0 < 250 Hz the deviation f0 increases rapidly with decreasing f0. We performed auxiliary experiments to find the pitches of high-pass and low-pass noise bands with sharp cutoffs at f0. The pitches deviate from f0 in the same way as for the binaural edge pitch. The correspondance supports the Equalization Cancellation model of binaural processing; it provides stronger support than does the Huggins pitch effect. Further experiments, with interaural phase changes from −π/2 to +π2, or changes superimposed upon a slowly varying phase shift show that the binaural processing must be a flexible system capable of enhancing local spectral features. Generally any abrupt change in interaural phase provides some pitch cue. [Work supported by NSF Grant BNS 79-14155.]
Infants' discrimination of full and partial cues to place of articulation in stop consonants
Authors: Aslin Richard N. , Walley Amanda C.
Published: October 2005

Stevens and Blumstein [J. Acoust. Soc. Am. 64, 1358–1368 (1978)] have proposed that the shape of the onset spectrum provides contextually invariant information about place of stop consonant articulation for CV syllables and that these primary spectral attributes underlie the. infant's ability to discriminate place differences. According to this view, contextually variable formant transitions constitute only secondary or “learned” cues to place of articulation. Prelinguistic infants are, therefore, assumed to be incapable of discriminating place differences in two-formant stimuli which supposedly lack invariant spectral attributes. Our analysis revealed, however, that the two-formant labial and velar CV stimuli are spectrally very similar to their full-formant counterparts. Therefore, if spectral shape does cue place of articulation, infants should actually discriminate these stimuli. An operant head-turning paradigm was employed to test this hypothesis with 6–9 month old infants. The results indicated that infants can discriminate two-formant stimuli—a finding which renders the distinction between primary versus secondary cues invalid. Moreover, because several infants discriminated the two-formant alveolar and velar stimuli, whose onset spectra are very similar, it is probably not the shape of the spectrum at stimulus onset which mediates infants' discrimination of place of articulation in stop consonants. [Work supported by NICHHD, NIMH, and Research Council of Canada.]
Pitch, timbre, and level of processing in a two-tone dichotic auditory illusion
Authors: McClurkin Robert H. , Hall Joseph W.
Published: October 2005

The Duetsch paradigm that produces a two-tone dichotic auditory illusion with alternating 400-and 800-Hz tones [D. Deutsch, J. Acoust. Soc. Am. Suppl. 1 55, S18–S19 (1974)] was modified to clarify aspects of pitch, timbre, and level of processing. The 400-Hz sinusoid was replaced by a high-frequency complex tone (1000-1200-1400 Hz) whose residue pitch was perceived as the low stimulus. Significant results based on the responses of 21 subjects indicated that the illusion is pitch, and not frequency, based. The effect of timbre was found to be negligible and the results suggest that the level of processing of the illusion is cortical rather than subcortical, as is presently thought.
Pitch of harmonic two-tone complexes of unequal amplitudes
Authors: Houtsma A. J. M.
Published: October 2005

Melodic interval identification experiments were performed using dichotic two-tone complexes of successive random harmonics with intensity ratios of lower to higher tone of 20, 10, 0, −10, and −20 dB. Experimental confusion matrices were correlated with theoretical matrices computed from Goldstein's optimal processor theory, Wightman's pattern transformation theory, and from an analytic pitch theory which assumes that a two-tone complex has one of two pitches, corresponding to the pure tone frequencies, with the likelihood of each pitch dependent on the relative loudness of the tone components. Results indicate that the best predictions are achieved by a combination of the optimum processor mode and the analytic mode. At low harmonic numbers, the optimum processor theory alone accounts very well for the data, while at higher harmonic numbers a combination of optimum processor and analytic theories yields the best correlation with observed data. At harmonic numbers higher than about six, correlation between data and any theory or combination of theories is clearly less than perfect, suggesting that pitch behavior at higher harmonics has some randomness which is not accounted for by any of the current pitch theories. [Work supported by NIH, Grant NS11680-03.]
Effects of stiffness and air loading on the normal-mode frequencies and decay rates of tympani membranes
Authors: Christian Richard S. , Tubis Arnold , Rossing Thomas D. , Mills Ronald I.
Published: October 2005

As part of a continuing study of the vibrations of air-loaded membranes with application to the orchestral tympani, we have studied experimentally and theoretically the normal-mode frequencies and decay rates for an unflanged clamped tympani membrane with free-air loading on both sides (no kettle). The effect of membrane stiffness is found to be negligible compared to that of air loading. Green's function techniques [R. S. Christian and A. Tubis, J. Acoust. Soc. Am. Suppl. No. 1 67, S85 (1980)] are used to calculate air loading effects. Comparisons are made of present results with previous ones for the case of kettle air enclosures.
Clarinet perturbation weight function measurements
Authors: Benade A. H. , Carman J. C.
Published: October 2005

To guide adjustment of woodwind playing properties, it is useful to know the modal frequency shifts (Δf/F)n produced by bore cross section perturbations Sp(x) in an air column of length L whose unperturbed cross section is S0(x). Modal perturbation weight functions Wn(x) are defined from first principles via (Δf/f)n =  ∫ 0L WnSpdx =  ∫ 0L [Kn − Un]Spdx/ ∫ 0L [Kn + Un]S0 dx. Here Kn(x) and Un(x) are the kinetic and potential energy densities of the nth standing wave. We have measured the set of Wn's for each of several representative fingerings on modern Boehm and Oehler system clarinets plus an early 19th century 6-key instrument. Experiments using a movable perturbing volume for frequency shift measurements in a self-oscillating feedback system agree with calculations based on probe microphone measurements of the standing wave. Both are consistent with basic theory when this takes account of small tapers, open and closed tone hole effects, and/or changes due to forked fingerings. Tone hole lattice phenomena are strongly present for frequencies above 12fcutoff. In general the clarinets behave similarly; but they differ significantly from cylindrical pipe systems for which Wn(x) = −cos (2knx)/S0L. [Work supported by NSF.]
On-line speech articulation display system for application in speech training and rehabilitation
Authors: Chuang Chiu Kuang
Published: October 2005

The use of vision and audition in guiding the development of motor kinesthesia for regulating skilled motor tasks, such as handfinger coordination in typing or tongue-jaw and phonation coordination in speech production, have received increasing interest among speech investigators (Van Riper, 1958; Ringel et al., 1962; and Chuang and Abbs, 1979). Individuals born with these primary sensory deficits, such as blindness and deafness, or with inherent motor function deficit, such as dysarthria, would conceivably become incapable of developing a corresponding normal motor skill, including speech, unless appropriate secondary sensory augmentation was made available (Whitehurt, 1961; and Klein and Posner, 1974). For those handicaps except blindness, a direct visual or visual-tactile combined form of articulation and its speech images' display is considered to be the most desirable learning aid to achieve comparable speech function (Norman, 1975). The opto-electronic tongue-jaw tracking and display system recently revised in the Speech Motor Control Laboratories by the author has obtained system functions, such as instant articulation image replayed with normal or reduced speed and multimovement time function displayed with speech amplitude, to be suitable for such application. In this report, the configuration, the operation function of this system and a preliminary application in correcting a young cerebral palsied adult's speech will be presented. [Work supported in part by NIH Grant NS 13274.]
Use of the NST with older listeners
Authors: Hiller S. M. , Danhauer J. L. , Edgerton B. J.
Published: October 2005

This study investigated the speech discrimination of two groups of older listeners (one group = 12 normally hearing; the other = 26 sensorineurally hearing-impaired) between 50 and 81 years of age. The Nonsense Syllable Test (NST) was presented via tape to each listener at seven sensation levels (SLs) between 5 and 65 dB re SRT. Listeners' responses were phonetically transcribed using both audio and visual cues and were scored by vowel, consonant, phoneme, and bisyllable methods. Inter-judge scorer reliability was high (94%). Articulation functions were plotted and analyzed for differences both within and between groups. Results revealed that: (1) the NST differentiated between the groups, (2) the four scoring methods differed, and (3) discrimination varied across SLs. The functions for the two groups were similar in shape, but evidenced differences in growth rate and D-max with the hearing-impaired scores being displaced below the normals. The normals reached a D-max of 89% by 55 dB SL for the phoneme method, while the hearing-impaired got 77% at that SL. Results compared well to and served as a needed extension of earlier findings.
[s] spectra in the speech of normally-articulating preschool children and adults
Authors: Weismer Gary , Elbert Mary , Whiteside Janet
Published: October 2005

[s] spectra from the speech of seven normally articulating pre-school children, and seven normally articulating young adults have been obtained from utterances recorded under highly controlled conditions [see Weisruer and Elbert, J. Acoust. Soc. Am. 67, S39 (1980)]. Spectral analysis is accomplished in the frequency range 0–10 kHz by sampling the middle 50 ms of [s] waveforms with a fixed-bandwidth, real-time analyzer (Spectral Dynamics SD 335). Several different types of analysis reveal the following: 1) Peak energy locations are fairly stable within adult subjects, but relatively unstable within child subjects, and 2) spectral shape for child and adult subjects tend to be dissimilar. These results are taken to be additional confirmation that children control their speech mechanisms less efficiently than adults, and may suggest that children have [s] source characteristics (that is, articulatory constriction shapes) which differ from the corresponding adult characteristics in systematic ways. [Work supported by NINCDS Award No. PHS R01 15551-01.]
Aberrant laryngeal devoicing gestures produced by deaf speakers: Evidence from acoustic, aerodynamic, and glottographic data
Authors: Whitehead Robert , Metz Dale
Published: October 2005

Aberrant laryngeal functioning may untowardly affect the voice quality of deaf speakers as well as their ability to instantiate appropriate prosodic elements and to differentiate certain consonants along the voicing dimension. Moreover, aberrant laryngeal functioning can directly affect respiratory and upper airway dynamics, particularly during glottal gestures associated with voiced/voiceless transitions. To gain a better understanding of these aberrant laryngeal gestures, acoustic, aerodynamic, and glottographic data were simultaneously collected on four deaf speakers while they produced isolated /ihi/ syllables. The results indicated: (1) abnormal abductory devoicing gestures characterized by excessively high air flow rates and protracted /h/ segment durations and; (2) abnormal adductory devoicing gestures characterized by a cessation of air flow, increased amplitude in the glottographic signal and protracted /h/ segment durations. These laryngeal gestures are discussed relative to their interaction with respiratory and upper airway dynamics and with specific reference to high speed laryngeal films which document their physiologic nature (D. Metz and R. Whitehead, preceding abstract, this meeting). [Supported by U.S. Department of Education.]
Teaching acoustics
Authors: Skudrzyk E. J.
Published: October 2005

Teaching acoustics is a special experience. Young students are not yet trained to think, and they have great difficulty grasping the basics of any new field they encounter, despite having been taught much of the mathematics in preceding courses. However, once they have learned the basics, they can easily handle the most difficult derivations that are presented to them. In my 400 level course, considerable attention is placed on the harmonic oscillator, on electromechanical analogies, and on circuit theory. About two million highly trained electrical engineers have worked on network theory during the last five decades. They have developed very powerful methods of dealing with linear systems that have no equivalent in classical theory. Examples presented in my acoustics class will convince the strongest adversary of circuit methods that not being acquainted with the theorems of circuit theory and not using them is like being a mathematician and not knowing calculus. Mathematics is a crutch that facilitates an understanding of complex sound phenomena, and much attention is placed on interpreting acoustic phenomena. Examples will be given of sound radiation by complex vibrators and of the relationship between abstract theory and physical understanding.
Free transverse vibrations of a uniform circular plate with an eccentric
Authors: Lin W. H. , Wambsganss M. W.
Published: October 2005

This paper deals with the problem of free transverse vibrations of a uniform circular plate with an eccentric hole. Using the method of trasforming cylindrical wave functions from one circle to another, the wave equation governing the transverse displacement of the plate is exactly solved to satisfy the boundary conditions at both inner and outer edges. The frequency equations for the vibrations of the plate with different boundary conditions are derived. This analysis also includes the vibrations of a uniform circular plate with a concentric hole as a special case. Numerical results are presented to show the dependence of the eigenwavenumber on eccentricity and the ratio of inner radius to outer radius. These results are in very good agreement with those obtained by other methods published in the literature. What distinguishes this study from others is that the exact analytical solution of the vibrations of an eccentric plate is obtained. Method of this study can be also applied to the studies of any eccentric waveguides and vibrations.
Acoustic radiation from an impulsively excited elastic plate
Authors: Mackertich Seroj S. , Hayek Sabih I.
Published: October 2005

The acoustic radiated pressure time signature of a submerged elastic plate which is impulsively loaded is predicted analytically by use of integral transforms on time and space. The first arrival of the acoustic pulse at an observer point in the medium was shown to correspond to the acoustic time of arrival for the normal distance from the observer to the plate. After the first arrival, the time signature oscillates with decreasing amplitude with the passage of time. The period of oscillation was shown to increase with time and the decay rate was shown to decay inversely with elapsed time. [Work supported by NAVSEA.]
Speech discrimination by macaques: enhanced discrimination at the phonetic boundaries between speech-sound categories
Authors: Kuhl Patricia K. , Padden Denise M.
Published: October 2005

Discrimination of speech-sound pairs drawn from a computer-generated continuum in which syllables varied along the Place of Articulation phonetic feature (/bae, dae, gae/) was tested with macaques. The acoustic feature that was varied along the 15-step continuum was the starting frequencies of the first and second formant transitions. Discrimination of stimulus pairs separated by two steps was tested along the entire continuum in a same-different task. Results demonstrated that peaks in the discrimination functions occur for macaque listeners at the “phonetic boundaries” which separate the /b-d/ and /d-g/ phonetic categories for human listeners. This effect of greater discriminability at the phonetic boundaries in macaque listeners replicates that seen in human listeners as young as one month of age. The data demonstrate that the results previously obtained with nonhuman listeners on the voiced-voiceless (/b-p/, /d-t/, /g-k/) phonetic feature can be generalized to another phonetic feature; this finding is a critical element in the general acceptance of the notion that speech-sound contrasts were chosen to be highly distinctive to the mammalian auditory system. [Supported by NSF.]
A quality control manual for a federal acoustical laboratory
Authors: Hawley Mones E. , Cook Richard K.
Published: October 2005

The Noise Enforcement Facility (NEF) of the U.S. Environmental Protection Agency in Sandusky, Ohio was created to assure the effective enforcement of Federal noise regulations issued pursuant to the Noise Control Act of 1972. The basic function of the NEF is to review and to monitor testing of regulated products by their manufacturers. A quality control manual was prepared for the stationary and mobile laboratory facilities used by NEF. The manual includes descriptions of the testing procedures for each product using each kind of facility, the organization of the test teams, the instrumentation used for each test, the calibration requirements of the instruments, the special requirements of the facilities, and the record keeping procedures that are necessary to provide a chain of custody for the products and the data. [The manual was prepared on EPA contract number 68-01-4703.]
Criteria for the accreditation of acoustical testing laboratories
Authors: Guernsey Richard M.
Published: October 2005

Guidelines for the Preparation of the Accreditation Section of Acoustical Test Standards have been proposed by the American Society for Testing and Materials (ASTM) Committee E-33 on Environmental Acoustics. The Guidelines, which were developed over a period of five years, recommend that a section on laboratory accreditation be included in every acoustical test standard to inform accrediting authorities what requirements should be satisfied by the facilities, instruments, procedures, and quality assurance program of an accredited laboratory. Accreditation programs will probably be instituted long before accreditation sections have been prepared for many test standards. Both potential accreditors and laboratories seeking accreditation should prepare for the advent of accreditation programs.
The use of the Biot-Tolstoy wedge-diffraction solution in computing the spatial coherence of ocean bottom interacting signals
Authors: Kinney W. A.
Published: October 2005

Biot and Tolstoy [J. Acoust. Soc. Am. 29, 381–391 (1957)] have devised solutions appropriate to a point explosive source for diffraction and reflection from a single wedge of arbitrary angle. Medwin and Novarini [J. Acoust Soc. Am. Suppl. 1 67, S67 (1980)] have used these solutions to model backscattering from the ocean surface. A model similar to that of Medwin and Novarini is discussed here wherein the solutions are used to predict the spatial coherence of energy scattered in the forward direction by a rough rigid ocean bottom. This model includes diffraction and reflection along with shadowing and has the potential for including bottom topographic characteristics explicitly or in a statistical form. The bottom is approximated by a collection of wedges (and troughs) each of arbitrary angle. The signal at a receiver is then taken as a sum of solutions for individual wedges and troughs. Finally, spatial coherence is determined using signals synthesized for two receiver points. The strengths and weaknesses of the model as well as the dependence of vertical and horizontal spatial coherence on bottom roughness are discussed. [Work supported by NORDA.]
Acoustic reflection and transmission coefficients at a planar interface of a porous medium exhibiting fast and slow compressional waves
Authors: Plona Thomas J. , Johnson David Linton
Published: October 2005

We have measured the reflected and transmitted amplitudes of ultrasonic pulses at normal incidence on a layer of water-saturated fused glass beads in which Biot slow compressional waves have been observed. [T. J. Plona, Appl. Phys. Lett. 36, 259 (1980)]. We have investigated water-porous medium interfaces and solid-porous medium interfaces; in the latter case, the nature of the bond is of critical importance to the amplitude of the slow wave generated at the interface. Due to mode conversion upon internal reflection, a pulse may traverse the layer on either a fast or a slow compressional wave. The results are interpreted in terms of boundary conditions derived from a general Lagrangian formulation derived previously.
Effect of a ground surface on blast wave propagation
Authors: Bass Henry E. , Raspet Richard R.
Published: October 2005

The effect of a complex ground plane on the waveform from a blast has been numerically simulated. This first approximation ignores all nonlinear effects associated with the finite amplitude of the wave. The input waveform taken from small charge explosion data is Fourier transformed; each of the Fourier components is propagated from the source to the receiver using the theory of Donato [J. Acoust. Soc. Am. 60, 34–39 (1976)]; the wave at the microphone is then reconstructed via on inverse transform. The reconstructed wave-form is strongly dependent on the range and assumed surface.
The precedence effect: Revisited
Authors: Yost William A. , Soderquist David
Published: October 2005

In 1949 Wallach, Newman, and Rosenszweig [Am. J. Psychol. 62, 315–326 (1949)] showed that the first of two binaural transients arriving at the ears was dominant in determining midline lateralization. This result has often been quoted as a demonstration of the precedence effect when transients are presented through headphones. We attempted to replicate these experiments in order to determine if: (1) under the original conditions the pair of binaural transients were in fact at midline, (2) this precedence effect exists for stimuli lateralized off-midline, and (3) this precedence effect could be obtained in a masking-level difference (MLD) paradigm. The binaural pairs of 60-μs transients were presented with I ms separation between the binaural pairs. In a variety of procedures the interaural temporal difference for the first binaural pair of transients was obtained which would yield midline lateralization as a function of the interaural temporal differences for the second binarual pair of transients. In general, these results, with some exceptions, support the conclusions of the original Wallach, Newman, and Rosenszweig study. A similar precedence effect was obtained when the fused images were off-midline and with the MLD procedure. Although the results generally support the rule that the first binaural transient is most important in determining lateralization, some exceptions will be discussed. [Work supported by grants from the National Science Foundation.]
Detectability of time-varying interaural intensity differences with narrowband noise stimuli
Authors: Grantham D. Wesley
Published: October 2005

In a two-interval forced-choice task observers discriminated a binaural AM noise in which the modulating sinusoid was interaurally in-phase from the same AM noise in which the modulator was interaurally phase-reversed. The latter stimulus produces a sinusoidally varying interaural intensity difference whose rate and magnitude depend on the frequency (fm) and depth (m) of modulation. The carrier was a narrowband noise, interaurally uncorrelated, centered at 500, 1000, or 4000 Hz. Presentation level was 75 dB SPL; duration was 1.0 s. For a given fm, m was varied in an adaptive procedure to estimate the depth required for 75% discriminability (mthr). At 500 Hz, for fm = 0 Hz, mthr = 0.09 (the interaural ΔI was 1.7 dB). For fm > 0 Hz, mthr increased with fm at a rate of 2 dB/octave, such that for fm = 50 Hz, mthr = 0.54. Thus, as the rate of variation increased, a greater peak interaural intensity difference was required to make the discrimination. The observers were generally more sensitive to interaural intensity at 1000 and 4000 than at 500 Hz, but the slopes of the functions (mthr versus fm) remained about 2 dB/octave. These results are quite different, in terms of both spectral dependence and steepness of the m function, from those on interaural correlation discrimination [J. Acoust. Soc. Am. 67, Suppl. 1, S5 (1980)]. [Supported by NSF.]
Recognizing foreign speech sounds: Dichotic fusion and learning strategy
Authors: Lambert David R.
Published: October 2005

Dichotic fusion screening tests of 96 subjects showed a uniform distribution from Fusers (F) to Nonfusers (NF). Twelve F and twelve NF then learned to recognize foreign speech sounds in a 2 × 2 (dichotic fusion x learning strategy) continuous recognition design. F learned 10% fewer words than NF did. Then, encoding speed and memorial comparison speed were measured using an auditory item recognition paradigm. Under Code Forming (CF) learning strategy instructions, NF acquired faster encoding speeds and slower memorial comparison speeds than F. Under Code Using (CU) instructions, differences between NF and F were much smaller. [“Learning to recognize foreign speech sounds: Strategies of auditory processing,” Doctoral dissertation, Pp. 330 (1977), PB-273 161/OGA.] [Work performed at Psychology Department, University of California at San Diego; supported in part by NIH.]
Auditory space perception
Authors: Wightman Frederic , Kistler Doris
Published: October 2005

We have begun a series of experiments in the general area of localization or auditory space perception. In these experiments, listeners hear sounds one at a time (either in free field or via headphones) from 20 or more source positions, and make judgments of the relative spatial distance between pairs of sounds. In the free-field conditions, the sounds are transduced by small loudspeakers (the responses of which are digitally flattened and matched) hung in an anechoic chamber. In the headphone conditions, the stimuli are digitally filtered to simulate a free-field listening condition. The listener's distance judgments are subjected to a multidimensional scaling analysis, which produces a three-dimensional representation of the listener's responses. This scaling solution is interpreted as reflecting certain features of the listener's auditory space. In the initial control experiments, using free-field presentations of wideband noise burst stimuli, the scaling solutions obtained from five listeners (in a triadic comparison paradigm) matched the actual physical arrangement of the sources with correlations of better than 0.95. [Research supported by NSF.]
Acoustics and electro-acoustics of the cinema theatre
Authors: Uzzle Ted
Published: October 2005

Changing economic and artistic demands on motion picture sound have created successive changes in format, acoustics, and electro-acoustics. This paper reviews quickly the last half-century and describes analytically the present situation: mini-cinemas in multi-theatre complexes, with one-, four-, or six-channel sound. The inherent limitations are discussed, as well as future possibilities.
Motion picture theatre electro-acoustic characteristics
Authors: Allen Ioan
Published: October 2005

The playback of Dolby Stereo films requires significantly improved electrical and electro-acoustic characteristics in the cinema if the full capabilities of the soundtracks are to be realized. The finished result can extend both the high and low frequency perceived cut-off frequencies by at least an octave. Some 2000 theatres have now installed new playback equipment. The paper describes typical theatre characteristics before modification, and the techniques necessary to achieve the desired electroacoustic response, now defined in ANSI Standard 2969. The possiblity of further improvements is discussed, within the confines of existing theatre technical personnel and test equipment.
Avoiding unwanted variations of low-frequency signal level in the output of a parallel formant synthesizer
Authors: Holmes John N.
Published: October 2005

In a parallel formant synthesizer producing very high quality speech [J. N. Holmes, IEEE Trans. AU-21, 298–305 (1973)] an extra resonator, FN, was used to help model the region below the frequency of F1. With this design it is difficult to derive an appropriate corresponding amplitude control, AN, because the low-frequency power has to be modeled by the sum of signals from FN and the lower skirt of F1. The ratio of contributions needed from these two sources is highly variable, although the total low-frequency power during voiced human speech varies very smoothly. To overcome this difficulty the AN control signal has been replaced by a new signal, ALF. An excitation signal whose amplitude is controlled by ALF has the F1 excitation subtracted from it before being used to excite FN. As the zero-frequency gains of the F1 and FN filters are equal the low-frequency output level is specified only by ALF, which can easily be derived from measurements on human speech. This modification has made it much easier to achieve good low-frequency performance in a formant vocoder, in synthesis by rule and in hand-optimized synthesis of high-quality speech.
Adaptive emulation of human speech by an articulatory speech synthesizer
Authors: Levinson S. E. , Schmidt C. E.
Published: October 2005

By controlling the parameters of an articulatory synthesizer [C. H. Coker, Proc. IEEE 64, 452–459 (1976)] with an unconstrained optimization technique, the synthesizer can be made to adapt to and emulate natural utterances. For ten simple English vowels in steady state we have observed convergence of the first three formants to within a few hertz of those of human speech in fewer than 25 iterations. In addition, the corresponding positions of the articulators are physiologically reasonable. We are currently studying methods for controlling the articulatory dynamics of the synthesizer in order to imitate temporally varying utterances. Details of the adaptation algorithm and experimental results are given. Finally the relevance of this study to problems in speech recognition, synthesis, and transmission is outlined.
Formant synthesis of speech on the digital signal processor
Authors: Kahn D.
Published: October 2005

The Digital Signal Processor is a Bell Labs-developed one-chip microcomputer featuring high-speed arithmetic, including multiplication, a fairly general instruction set, and on-chip RAM, and program memories. Though not specifically designed for this purpose, its capabilities are such as to allow digital formant synthesis of high-quality speech in real time at output sample rates in excess of 10 kHz. This paper describes a speech synthesizer built around the DSP chip. The basic structure of the synthesizer is implemented totally in software and consists of pitch pulse and noise generators, a glottal shaping resonator, a five-formant-one-antiformant glottal-excitation branch, an independent fricative branch, and associated control logic.
Lingua and prosody
Authors: Browman Catherine P.
Published: October 2005

LINGUA, a general purpose set of programs used to synthesize speech from demisyllables, presented a paper describing its structure and operation in the April, 1980, ASA meeting. At that time, the prosodic rules were quite rudimentary. Since then, a number of refinements have been introduced. For example, pitch and duration are no longer controlled in lock-step, but may vary independently of each other; thus stress may be correlated with high pitch phrase-initially, and with increased duration phrase-medially, as suggested by Nakatani and Aston (1980); stress may also be correlated with low pitch. A variety of pauses have also been introduced in order to improve naturalness; the pauses vary both in duration, and in their effect on the intonation contour. The speech output will be demonstrated.
Extraction of spectral information in auditory brain stem nuclei; hypothesis and experimental observations
Authors: Merzenich Michael M. , Loeb Gerald E. , White Mark W.
Published: October 2005

Psychophysical evidence strongly suggests that there is a central neural pattern of representation of sound frequencies; and that the overall pitch of any sound is a function of this central pattern. Physiological studies on the discharges of auditory nerve fibers as a function of cochlear location, and psychophysical studies employing controlled electrical stimulation of the auditory nerve array in man strongly indicate that the spectral composition of complex sounds is not extracted from either discharge rate versus position profiles across the auditory nerve array (the “cochlear place”), or by measuring input discharge periodicities per se. It is hypothesized that spectral components of sounds are extracted from the relative timing of discharges of auditory nerve fibers from separated locations along the auditory nerve array. To extract a spectral representational pattern with broad dynamic range, comparator neurons must detect the synchronicity of arrival of input from separated basilar membrane locations with a resolution of 10–20 μs. It is hypothesized that this extraction is effected by the neurons of the medial superior olive, which operate as monaural as well as binaural time comparators. Psychophysical and physiological data supporting testable predictions of this hypothesis will be reviewed. [Work supported by NIH Contract N01-NS-7-2367 and NIH Grant NS-11804.]
The frequency following response to vowel-like signals
Authors: Resnick Steffi , Heinz John , Talkin David
Published: October 2005

This paper presents the results of a preliminary investigation designed to document the characteristics of the auditory frequency following response (FFR) to computer-synthesized vowel-like signals in normal-hearing young adults. The signals were single glottal periods of the synthetic vowels /ɑ/, /u/, and /i/ delivered monaurally at approximately 60 dB SL at a rate of 8.5/s. The signals were delivered via an electrostatic earphone which had been modified to minimize the effect of stimulus artifact on response recording but which preserved the frequency response of the transducer. Preliminary analyses of the scalp-recorded potentials indicated marked intersubject differences in the response waveforms. In some instances, spectral analyses of the response waveforms revealed spectral peaks corresponding to the first formant and its harmonics or to both the first and second formant of the vowel-like signals. In other instances, spectral analyses of the responses revealed either no spectral peaks or peaks which differed slightly in frequency from the formant frequencies of the signals. [Work supported in part by Biomedical Research Support Grant (RR-05808) to the John F. Kennedy Institute: NIH.]
A comparison between the Biot-Tolstoy exact solution for wedge diffraction and a related solution that involves the Kirchhoff approximation
Authors: Kinney W. A. , Clay C. S.
Published: October 2005

Biot and Tolstoy [J. Acoust. Soc. Am. 29, 381–391 (19571] have used the normal coordinate method to obtain a simple exact expression for the impulse response of a rigid wedge. This solution is appropriate to arbitrary wedge angle as well as arbitrary point receiver and explosive point source locations. Trorey [Geophysics 35, 762–784 (1970)] has developed a simple expression for the back-scattered impulse response of a half plane in the Kirchhoff approximation. The Biot-Tolstoy solution has been used by Medwin and Novarini [J. Acoust. Soc. Am. 67, S67(A)(1980)] to model back-scatter from the ocean surface. In doing so, they evaluated the accuracy of a similar but earlier model [J. Acoust. Soc. Am. 64, 260–268 (1978)] that used the Trorey Helmholtz-Kirchhoff solution. Because of the nature of the Kirchhoff approximation, the Trorey solution ignores field effects associated with shadow zones. The Biot-Tolstoy solution, on the other hand, does not. Here, an explicit comparison between the two solutions for simplified geometries (e.g., a single half-plane wedge) is discussed. [Work supported by NORDA.]
Biot rough surface boundary conditions and boundary waves
Authors: Tolstoy Ivan
Published: October 2005

Given radiation of wavenumber k incident upon a plane z = c with roughness elements of mean separation h and dimensions d ≅ h or d ⩽ h, assuming kh ⩽ 1, the calculation of the coherent scatter is equivalent to solving the wave equation with a linear boundary condition applied at z = c. This condition was first derived by Biot [J. Acoust. Soc. Am. 44, 1616–1622 (1968)] for the case of a perfectly rigid wall. The result has since been elaborated and extended to the case of a rough boundary between liquids of different densities [I. Tolstoy, J. Acoust. Soc. Am. 66, 1135–1144 (1979); 68, 258–268 (1980)]. A result of the theory which has been verified experimentally [H. Medwin et al., J. Acoust. Soc. Am. 66, 1131–1134 (1979)], is a new type of boundary wave. A result which awaits experimental confirmation is that this wave offers an efficient mechanism for the transmission of energy into regions of shadow. Since analogous boundary conditions can be derived for the electro-magnetic case [M. A. Biot, J. Appl. Phys. 29, 998 (1958)] this mechanism is also relevant to the transmission of electromagnetic waves beyond the horizon. [Work supported by ONR.]
Binaural interaction asymmetries in human ABR's
Authors: Lobaugh Paul , Parker David , Thornton A. R. D. , Berlin C. I.
Published: October 2005

Ten normal listening subjects heard 100 μs electrical pulses transduced by a TDH-49 headphone, presented monaurally and then binaurally at 60 dB HLn. Auditory brain stem responses were recorded from the scalp in 12 referential and differential configurations: M1, M2, T3, T4, C3, C4, (C2 − M1), (C2 − M2), (T3 − M1), (T4 − M2), (C3 − M1), and (C4 − M2). We found a binaural interaction asymmetry not ascribable to any individual monaural asymmetries nor to any acoustic or vibro-tactile “cross-talk” between the sides. This binaural interaction asymmetry reverses in polarity between mastoid and temporal sites and can be recorded at approximately 6-ms latency from all the recording sites used. [Work supported by scholarships from Ohio University, MRC Grant 9634/19, The Burroughs Wellcome Fund and NINCDS No. NS-11647.]