bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Comparison of Perception of Nasality and Cinefluorographic Analysis of the Velopharyngeal Mechanism
Authors: Massengill Raymond , Love Laura R. , Robinson Mary
Published: October 2005

There is a continuing question in clinical literature about what is meant by the term “nasal speech” and about the measurement of this phenomena. Bzoch (1971) and others (Moll, 1968, and Kantner, 1964) insist upon an operational definition, which includes a listener's general perception of acoustic features of the voice quality. Bzoch also states that velopharyngeal insufficiency alone may not be a determinant of hypernasality. This study investigates the relationship of degree of velopharyngeal gap, as determined by cinefluorographic, to listener judgements of hyper- and hyponasality. Two judges rated 30 subjects with a known degree of velopharyngeal gap on a five-point scale. This allowed the judges to assess the voice quality as +3, severely hypernasal, to −3, severely hyponasal, with a midpoint of 0 for normal. The velopharyngeal gaps were ranked in three categories for comparison; 0 as normal, 1 to 5 mm as moderate hypernasality, and beyond 6 mm as severe hypernasality. The judgments were compared between judges and between judges and degree of velopharyngeal gap. The reliability of the intrajudge ratings were also examined. These results and their importance to research are discussed.
Stress-Wave Propagation in a Class of Elastic Rods
Authors: Dökmeci M. Cengiz , Alpd M.
Published: October 2005

A non-classical theory of elastic rods of uniform cross sections, descriptive of wave propagation and vibrations, is constructed within the scope of the theory of Cosserat elasticity. A separation of variables solution is sought for the three-dimensional field equations, and a generalized variational theorem is used in the analysis. The effects of transverse shear and normal strains as well as those of rotatory inertia are taken into account. The microrotational motions give rise to new type of waves not present in any of the known rod theories. In particular, the nature of extensional waves is discussed and the uniqueness of solution is established. The results are valid for both nonpolar and Cosserat rods, and contain those of earlier theories as special cases. [Supported by the Office of Naval Research.]
Statistical Behavior of Source-Receiver Locations in a Reverberant Room
Authors: Lyon Richard H. , Ingalls Dourglas J.
Published: October 2005

The pure-tone, narrow-band, and 13-oct band probability distribution functions of the SPL for source positions (located on the floor) and receiver positions (located in the interior away from boundaries) were investigated for a random dipole source (Ilg Reference Sound Source), a dipole source (unbaffled loudspeaker), and a monopole source (loudspeaker) for frequencies from 100 to 4000 Hz. The experimental data indicate that an experiment in a reverberant room must be carefully defined. A theoretical model is advanced to explain the observed results.
Tape Cutting Experiments with Stop Consonants
Authors: Fischer-Jorgensen Eli
Published: October 2005

In Danish words with /p,t,k,b,d,g/+/i,a,u/, stop bursts, aspirations, and formant transitions have been removed and exchanged. [Danish /p,t,k/ are strongly aspirated (/t/ affricated), /b,d,g/ are voiceless.] 500 stimuli were presented to 21 listeners, who had to identify the words. Main results were: For the distinction between /p,t,k/ and /b,d,g/, the small difference in stop burst is insignificant, whereas the aspiration is decisive (a simple pause between burst and vowel is not sufficient). The duration of the aspiration is important, but the start of the vowel (noisy start of higher formants) may be sufficient for the identification of /p,t,k/, particularly before /a/, even with VOT values of 20–30 msec. For the identification of place of articulation the aspiration (affrication) of /p,t,k/ is sufficient except for /k/+/a/, but the burst is also sufficient except for t. In /b,d,g/ the transition is sufficient if it is extensive (e.g., /ba/, /da/, /ga/, /bi/, /du/); it is not enough that it points to the locus. The burst is necessary not only in velars before rounded vowels, as previously assumed, but also, for example, in /bu, /di/, and /gi/.
Phonetic Coding of Kanji
Authors: Erickson D. , Mattingly I. G. , Turvey M.
Published: October 2005

An experiment in the recall of visually presented Japanese Kanji ideograms suggest that Kanji may, like alphabetic words, be encoded phonetically, despite their lack of phonetic structure. The experiment, based on Kintsch's and Buschke's (1969) paradigm, assumed that similarity of items in a list increased errors in recall. Four lists were prepared, each containing 16 different Kanji. The first included phonetically similar pairs of characters; the second, semantically similar pairs; the third, visually similar pairs; the fourth was a control list containing no similar pairs. The subjects, 10 native speakers of Japanese, were presented with randomly ordered versions of each list, at one character per second. After a subject had seen an entire list, he was presented with a cue character selected from the list, and asked to recall the character that had been presented immediately before the cue. Confusion in recall was significantly greater for the phonetic list than for the other lists. These results strengthen the hypothesis that regardless of structure, visually presented linguistic items are, like speech itself, phonetically processed.
Ultrasonic Welding for Electrical Conductivity Applications
Authors: Jones J. Byron
Published: October 2005

Ultrasonic welding, which produces bimetallic as well as monometallic junctions of integrity at temperatures below about one-half the absolute melting value, is effectively used in electrical conductivity applications such as making wire terminal connections, attaching armature coils to commutator bars, and consolidating stranded copper and/or aluminum wire into solid sections. New aluminum conductivity alloys exhibiting improved physical properties, coupled with the economic lever existent in substituting aluminum for copper, have triggered extensive efforts to utilize the ultrasonic welding process in electrical equipment particularly for the automotive, appliance, and aircraft industries. Harnesses and starting motors are discussed, and ultrasonic welding data for such applications, including equipment size, power, operating parameters, and product quality, are presented.
The Nature of Sound Fluctuation in Continuous, Statistically Isotropic Media
Authors: Neubert J. A.
Published: October 2005

The stochastic Eulerian-Lagrangian procedure, which was reported earlier, is reviewed heuristically and applied to steady-state sound propagation from a small, collimated acoustic source to an omnidirectional point receiver imbedded in an infinite, continuous, statistically isotropic medium (such as a turbulent fluid.) Part I relates the analysis to ray-trace type relations and emphasizes the need to use Eq. 14 of “Approach to an Eulerian-Lagrangian Problem for Sound Propagation in Continuous Stochastic Media” [J. A. Neubert, J. Math. Phys. 12, 1030–1034 (1971)]. The physical problem is then clearly stated and illustrated.
Horn Theory and the Phonograph
Authors: Wilson Percy , Wilson Goeffrey L.
Published: October 2005

This paper describes the development of horn theory from Rayleigh, through Webster, Hanna and Slepian, Percy Wilson, P. B. Flanders, and Paul Voigt up to the comprehensive analysis by Leo Beranek. It includes an account of some early experiments by the senior author on methods of folding horns. A description is also given of a recent acoustic phonograph with a fabulous response down to 30 Hz thanks to loading by an external exponential horn that is curved rather than folded.
Sound Fields near Arrays of Noise Sources
Authors: Salmon V.
Published: October 2005

When sound from different portions of an extended radiator is essentially noncorrelated, the source is said to be spatially incoherent (SI). Such sources can be characterized by power radiated per unit length, area, or volume. The total field is then obtained by power addition, using the inverse square law. The consequences of this simplifying assumption for measuring machine noise will be reviewed in the light of work by Salmon, Maekawa, Embleton, Shaw, and others.
Nearfield Measurements and Sound Power
Authors: Angevine O. L.
Published: October 2005

The measurement of noise generated by large machines in ordinary semireverberant rooms can only be done very close to the machine at distances which appear to be well within the nearfield of the machine considered as a single large noise source. But large machines are usually composed of a number of smaller incoherent noise sources. Arrays of such sources show the farfield beginning at distances comparable to the measuring points at 1 m from the machine used in the CAGI standard, or the prescribed path of ISO Recommendation 1680. Such measurements corrected to a uniform radius are used to determine total sound power. The results agree well with sound power calculated for the same machine from farfield measurements.
A Model for Residue Pitch
Authors: Thomas Ian B. , Ravindran A.
Published: October 2005

We have developed a model of pitch perception that accurately predicts all subjective (residue) pitches measured in the experiments of Schouten, Ritsma, and Cardozo [J. Acoust. Soc. Amer. 34, 1418–1424 (1962)]. The primary assumptions of the model are (1) that the transfer function relating amplitude of basilar membrane displacement at a particular membrane location to acoustic pressure external to the ear represents a bandpass filter of low selectivity and frequency-dependent phase change; (2) that the pattern of axis crossing intervals of the signal representing basilar membrane displacement at any membrane location is neurologically encoded and analyzed; (3) that there is a mechanism capable of detecting a variation of approximately 0.3% in the duration of axis crossing intervals for the frequency range considered. Prediction of residue pitches requires no assumption of nonlinear distortion anywhere in the filtering process, nor does it require the presence of any amplitude encoding mechanism such as an envelope detector. The model also predicts perception of the difference tone without any appeal to nonlinear processes. Prediction of more complex combination tones does require the assumption of nonlinear distortion in the filtering process. The model gives at least qualitatively satisfactory explanations for other auditory phenomena such as the critical band and masking. [Work supported by NIH.]
Some Properties of Response Patterns in the Cochlear Nerve of the Pigeon
Authors: Sachs M. B. , Lewis R. H. , Young E. D.
Published: October 2005

Discharges from more than 200 single fibers in the cochlear nerve of the pigeon have been recorded with NaCl-filled micropipets. The median rate of spontaneous activity for these fibers is approximately 80 spikes/second, with some fibers discharging at rates higher than 150/second in the absence of controlled acoustic stimuli. Responses to low frequencies (less than 4.0 kHz) are phase locked. Isorate contours have been measured, taking as response measures both average rate of discharge and number of synchronized spikes per cycle. Characteristic frequencies for the population studied lie in the range 100 Hz to 6.5 kHz. Click-response patterns are similar to those seen in the cat. Two-tone inhibition is also demonstrated. [Supported by the National Institute of Neurological Disease and Stroke and the U. S. Air Force Office of Scientific Research.]
Ototoxicity of Ethacrynic Acid Enhanced by Barbiturate Anesthesia
Authors: Wilpizeski Chester , Isaacson Stephen , Saliman Salah
Published: October 2005

VDLs and input-output functions for CM and AP were recorded under waking and anesthetized conditions (35 mg/kg of pentobarbital sodium) from guinea pigs having implanted depth electrodes localized in the chochlear nucleus region or flexible electrodes fixed against the round-window membrane. Following control recordings, animals were injected intraperitoneally with 50 mg/kg of ethacrynic acid and measurements repeated at 1, 2, and 4 h post drug. AP VDLs for clicks were elevated 15 dB, and suprathreshold evoked response amplitudes were reduced below normal at low to moderate stimulus intensity levels. CM VDLs for pure tones recorded during barbiturate anesthesia shifted 35 dB (median for all pure tones) but only 15 dB under waking conditions. Slopes of CM input-output functions were not altered by ethacrynic acid as were AP amplitude curves; rather, CM slopes remained invariant and parallel but were depressed compared with control values.
Release of Acetylcholine by the Olivocochlear Bundles
Authors: Guth P. S. , Burton M. , Norris C. H.
Published: October 2005

The mechanism by which the olivocochlear bundle (OCB) fulfills its presumed feedback inhibitory role is unknown. However, acetylcholine (ACh) has received experimental support as the inhibitory mediator of the OCB hair-cell junction. In the present investigation, the ability of the OCB to release ACh upon electrical stimulation was tested. Guinea pigs, anesthetized with pentobarbital and immobilized with gallamine, were prepared for this research by placing recording electrodes on both round windows, stimulating electrodes on the floor of the fourth ventricle, and push-pull perfusion pipet in the scala tympani and scala vestibuli of one cochlea. The cochleas were perfused with artificial perilymph containing eserine. Samples of perfusate were collected before, during, and after OCB stimulation and bioassayed for ACh-like activity on the isolated guinea pig ileum. The authenticity of the ACh-like activity, when present, was verified by hydrolysis by acetylcholinesterase or antagonism by low concentrations of atropine. Concentrations of ACh-like activity detected in the perfusate were of the order of 10−11 moles/ml. An increase in the ACh-like activity was seen in conjunction with OCB stimulation. [Supported in part by V. A. 71-6.]
Computer Simulation of Cochlear-Microphonic Potential Augmentation During Intracochlear Perfusion
Authors: Moscovitch David H. , Laszlo Charles A.
Published: October 2005

In previous studies, “start-stop” perfusion of scala tympani by artificial solutions produced temporary augmentation of the CM recorded by differential electrodes. The significance of hydrodynamic changes in scala tympani and the differential action of the artificial and natural perilymph on the hair cells in this phenomenon was investigated by computer simulation. In particular, it was determined from fluid-dynamic and experimental considerations that the artificial perilymph perfusate could be spontaneously replaced by natural perilymph at a rate of 0.8 μliter/min. The effect of this replacement was simulated on a computer model of the mechanoacoustical and mechano-electrical transduction process of the guinea-pig ear [C. A. Laszlo, J. Acoust. Soc. Amer. 38, 93(A) (1971)]. After simulated injection of a solution whose action was to suppress the CM generated by individual hair cells, the modeled gross CM was temporarily augmented by 40% above the preperfusion control, comparable to that observed in our perfusion experiments. The results indicate that the experimentally observed CM augmentation may be due to partial suppression and spontaneous progressive recovery of the CM generators, resulting in the detection of an apparant rather than a real CM augmentation. [Work supported by the Medical Research Council of Canada.]
Practical Sound-Power-Level Measurements
Authors: Eriksson L. J.
Published: October 2005

The measurement of sound-power level in semireverberant rooms is discussed. The standard equations for calculating sound-power level in reverberant and semireverberant rooms are compared. It is shown that for many practical measurements, the two equations produce essentially the same result. In particular, when the area of the room is equal to four times the area of the hemisphere surrounding the source, the results are identical under normal room conditions. This is also true for a cube-shaped room, if the distance from the source is one-half the wall dimension. Sound-power-level measurements made in three semireverberant rooms on a small electric motor are reported to illustrate this result. The effect of a partial enclosure on the sound-power level is also discussed.
Multipole Expansion of Sound Radiation from Moving Rigid Bodies
Authors: Eisler Thomas
Published: October 2005

The solution of the wave equation with a source term extended in space and moving as a rigid body with translation and rotation is expanded about an interior point in terms of point multipoles, which are expressed as spatial derivatives of the Lienard-Wiechert solution for a monopole. An application to sound radiation from moving rigid bodies is given using the theory of Ffowcs-Williams and Hawkings [Phil. Trans. Roy. Soc. London A264, 321 (1969)]. As examples, the radiation fields of a rotating ellipsoid and a sphere in accelerated rectilinear motion are estimated.
Mutual Radiation Impedance between a Circular Piston and a Piston of Arbitrary Shape
Authors: Stepanishen P. R.
Published: October 2005

A time-domain approach is presented to compute the mutual radiation impedance between a circular piston and a piston of arbitrary shape where both pistons are mounted in a rigid planar baffle. The approach is based on numerically evaluating the Fourier transform of an impulse response, which is equivalent to the time-dependent force on the piston of arbitrary shape resulting from the impulsive velocity of the circular piston. An integral expression over a single variable is presented for the impulse response between the circular piston and an arbitrary shaped piston. The mutual impedance between a circular piston and a concentric annular ring is investigated as a special case. A closed-form expression is derived for the impulse response, which is shown to consist of two pulses that are associated with the edges of the ring. Numerical results for the mutual impedance are then presented as a function of frequency and the impedance is shown to be zero for certain critical frequencies. The configuration of two unequal circular pistons is also discussed as a special case, and numerical results are presented for the impulse response and impedance as a function of frequency.
Nonlinear Effects in Helmholtz Resonator Mufflers for Internal Combustion Engines
Authors: Brammer A. J. , Olson N. , Piercy J. E. , Toole F. E.
Published: October 2005

The design of exhaust mufflers for internal combustion engines in practice tends to rely heavily on empirical art. One reason could be that the available theory is generally linear (hence suitable for low sound levels) and the levels inside the muffler are too high. We have chosen a simple case, one-stage Helmholtz resonator mufflers mounted on a small one-cylinder two-cycle engine, to test experimentally for nonlinear effects. Some configurations that are equivalent according to linear theory are found to produce insertion losses which differ by at least a factor of 2, as measured in dBA. Experimental evidence indicates the configuration in which tail and exhaust pipes are aligned is particularly ineffective because nonlinear jetting of the type analyzed previously for orifices by Ingard and his colleagues tends to bypass the volume.
Economics of Noise Control in New York State
Authors: Teplitzky Allan M.
Published: October 2005

Department of Labor occupational noise-exposure standards will not protect all employees from hearing loss. For an occupational noise exposure of 90 dBA for 8 h/day for 10 years or more, the expected New York State Workmen's Compensation award per employee per year is estimated to be $25. A comprehensive hearing conservation program to reduce an employer's liability for hearing loss could be financed by savings in potential compensation awards. Similarly, in plants where the occupational noise environment exceeds O.S.H.A. noise-exposure requirements, expenditures for engineering methods for noise control may be economically justified by savings in potential compensation payments. This paper reviews the methodology for determining the expected employee compensation award for occupational hearing loss and relates it to potential hearing conservation program costs.
Advantages of a Two-Transducer Frequency Analysis Technique to Characterize Discontinuities
Authors: Adler Laszlo , Whaley H. L.
Published: October 2005

In an earlier paper [J. Acoust. Soc. Amer. 48, 102(A) (1970)], we have shown that the frequency analysis of a broad-band ultrasonic echo may be used to determine the size and orientation of flat circular reflectors. A single transducer was used as both source and receiver. The one-transducer technique is not completely satisfactory for the case of discontinuities having both random shape and orientation. Recently, we have used a second transducer to receive ultransonic pulses scattered by a reflector. Defects in materials were simulated by irregularly shaped metal shims suspended with random orientation in water. The received frequency spectrum when analyzed shows characteristic maxima and minima, which depend on the shape, size, and orientation of the reflectors. A model—which assumes an interference pattern formation of the scattered spherical wavelets at the receiver—relates the spacing between frequency maxima and the positions of the two transducers to the size and orientation of the “discontinuities.” The measurement and the analysis is greatly simplified with the use of the second transducer, and size determination of the discontinuities can usually be made within 10%–20%. [Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corporation.]
Masked Threshold at Reduced Ambient Pressure
Authors: McGregor Howard N. , Galipeau Albert A.
Published: October 2005

Differences in signal tone perception between 1 atm (14.7 psia) and 13 atm (5.0 psia) in the presence of background noise were investigated. In addition to the generation of a background noise spectrum conforming to that specified for spacecraft of the Skylab program (NC 55 approximately), predicted acoustic properties of the spacecraft were simulated. SPLs of three signal tones were experimentally varied using the “Block Up-and-Down, Two-Interval Forced-Choice” technique. Masked thresholds were determined for the three signal tones under the two air pressure conditions and compared with predicted masked thresholds and subjective preferences. The data indicate that the difference in ambient pressure between 14.7 and 5.0 psia does not significantly affect masked thresholds, nor does this difference in ambient pressure affect subjective preferences for signal tone SPLs or sound quality. A further finding indicated that reduced pressure significantly affected the SPL of sound producing equipment in that the SPL decreased with a decrease in pressure but not in accordance with the expected formula 10 log10(ρc/ρ0c0). [This study was supported by a NASA contract.]
“Unbiased” Procedure for Comparing Degree of Lateralization of Dichotically Presented Stimuli
Authors: Harshman Richard , Krashen Stephen
Published: October 2005

In some experimental designs, it is desirable to compare “degree of lateralization” for different stimuli or different groups. Current measures of ear difference make such comparisons difficult, because scores are influenced by subjects' relative accuracy in identifying the stimuli. One reason for this “bias” is demonstrated using some simple mathematical models of a subjects' behavior in dichotic listening. A scoring method is deduced that is not biased by different amounts of guessing by subjects. This procedure, the percent of errors method (POE), consists of computing each ear's percentage of the total number of errors. The utility of the POE method is confirmed by reanalysis of previously published data. Standard methods for measuring ear difference are found to be negatively correlated with changes in accuracy. POE scores, however, do not correlate significantly with accuracy scores. This is true whether accuracy differences are due to age, first versus second channel reported, or differences in stimulus difficulty. Reanalysis of consonants versus vowels, younger versus older subjects, and other comparisons of degree of lateralization suggest some alternatives to previous conclusions.
Individual Differences in the Annoyance of Noise
Authors: Angevine O. L.
Published: October 2005

Among the factors influencing individual appraisals of noise intrusion or annoyance are the information contained in the noise, the person's conditioning, and his interpretation of what the noise represents. His previous adaptation to the noise, and his expectations as to the level and the difficulty of quieting it also affect his estimate. Cultural differences in conversational voice level and speaking distance affect the evaluation of background noise. Daily and monthly rhythms occur in sensitivity. All of these factors serve as a caution that the individual response may depart from the “average” reaction.
Text-Independent Speaker Recognition
Authors: Atal B. S.
Published: October 2005

In automatic speaker recognition methods, the speaker to be recognized is usually required to speak the same utterance which was used to obtain the reference pattern for that speaker. However, such a restriction is not generally necessary for speaker recognition by humans. Is reliable automatic speaker recognition similarly possible? A speaker identification experiment was performed in a population of 10 female speakers. The acoustical information was represented by sets of 12 predictor coefficients obtained by minimizing the mean-squared prediction error over speech segments 50 msec in duration. Each set of these predictor coefficients was represented by a 12-dimensional vector. New sets of coordinates which minimized the intraspeaker variance were determined by linear transformation of the original vector space. The segment of the utterance used to identify an individual was different from the segments used to form the reference pattern for that individual. For each segment, the unknown vector was correlated with the reference vectors and the correlations were averaged over a number of segments—the speaker with the largest correlation was identified as the unknown speaker. The over-all identification accuracy was 93% for 40 speech segments. These results suggest that successful automatic speaker identification is possible independently of the spoken text.
Estimation of the Vocal-Tract Shape by Optimum Inverse Filter Processing of Speech
Authors: Wakita H.
Published: October 2005

It is shown that the filtering process of the optimum inverse filter [J. D. Markel, SCRL Monogr. No. 7, 111 (Oct. 1971)] is identical to the filtering process of the nonuniform acoustic tube model [B. S. Atal and S. L. Hanauer, J. Acoust. Soc. Amer. 50, 637 (1971)] in which the vocal tract is divided into a finite number of sections with equal lengths. The common factor between the two processes is shown to be a set of reflection coefficients. These reflection coefficients are obtained as intermediate results of a recursive solution to the inverse filter equations. Both area functions and filter coefficients can be easily determined from this set of reflection coefficients. The procedure can be realized by recursive digital filters, thus making possible an efficient implementation as a computer program to obtain the time variation of the vocal-tract shape together with the spectral envelope of the speech sample. This procedure simplifies finding the relationships between the vocal-tract shape and its acoustic features, e.g., from the vocal-tract shape to the filter coefficients, from which formant frequencies and bandwidths can be determined, and vice versa. Applications and limitations of this procedure to connected speech are discussed. [The work was supported by the Office of Naval Research.]
Morphological Correlates of Asymptotic Temporary Threshold Shift in Chinchillas
Authors: Lim David , Melnick William
Published: October 2005

Using the scanning and transmission electron microscopes, an attempt was made to correlate morphological and behavioral data from conditioned chinchillas following their exposure to a presumably subtraumatic level of noise that produced asymptotic TTS. Varying degrees of morphological change in the sensory cells, which could be attributed to the noise exposures, were observed in these animals. Changes included giant cilia formation, sensory cell debris, cellular swelling, and scar formation. Changes also appeared in the stria vascularis. These morphological changes were most pronounced in the apical turn of the cochlea. Our preliminary data appear to support the idea that sensory cell degeneration occurs even after exposure to a noise level considered subtraumatic and which apparently does not produce permanent changes in behavioral threshold hearing levels.
Measurements of the Transient Response of the Basilar Membrane Using the Mössbauer Technique
Authors: Robles L. , Rhode W. S. , Geisler C. D.
Published: October 2005

Measurements were performed on 25 squirrel monkeys, using an experimental preparation identical to the one used by Rhode to measure frequency response [J. Acoust. Soc. Amer. 49, 1218–1231 (1971)]. The stimuli used were acoustic clicks, about 150 μsec in duration, presented in sequences of 100 000 to 400 000. Clicks with different amplitudes were used, and the responses of the basilar membrane at a point in the basal turn and of the umbo were measured. The results indicate that the click response of the basilar membrane at the points measured is a lightly damped oscillation with a natural frequency between 6 and 8 kHz. There is an initial part of the response that has a faster decay and a later part that has an extremely slow rate of decay. This later part of the response displays a nonlinear behavior for changes in amplitude of the stimulus. Even when the general features of the vibratory pattern were stable for a period of hours, there was usually a marked decrease with time in the number of cycles which could be observed. [Supported by NIH Grants.]
Experimental Determination of the Area Function of a Lossy, Dynamically Varying Vocal Tract
Authors: Sondhi M. M.
Published: October 2005

During the last year we have made acoustic impulse-response measurements at the lips while the vocal tract is moved as in normal speech. The experiment will be described and moves will be shown of the area functions reconstructed from the measurements. A method will be presented for estimating the mechanical impedance of the walls of the vocal tract. It will be shown that the reconstructed areas are significantly improved if the walls, instead of being assumed rigid, are assumed to have this estimated impedance.
Models of Articulatory Dynamics
Authors: Coker C. H. , Browman C. P.
Published: October 2005

We present comparisons between the x-ray data of R. A. Houde [PhD Thesis, Univ. of Michigan (1967)] and actions of a dynamic articulatory model. The data can be fitted in two ways: (1) a model with minimum number of degrees of freedom, but with time-varying “characteristic filters” (Coker and Fujimura, J. Acoust. Soc. Amer. 40, 11(A) (1966)]; or (2) one in which different speeds of an articulator are produced by additional “characteristic variables” that would be redundant in the static case. The phenomenon that the constriction tends to move forward during /g/ was suggested by Houde to result from pressure buildup in the enclosed cavity. We treat the effect as a peculiarity in “programming” of /g/. Horizontal motions toward /g/ from front vowels are commanded 50 msec early, from back vowels, 50 msec late, thus producing a circular Lissajous pattern of motion. The dilemma of cause and effect (whether continued voicing forces tongue-body movement, or whether movement is explicitly commanded, to sustain voicing) leads to interesting questions when we attempt to generalize to other phonemes. Does circular motion occur in nasals and voiceless stops as well as /g/? Does the tendency for /g/ to devoice in some languages derive from differences in tongue control? These and other topics are discussed.
Some Relationships between Vocal Effort and Intraoral Air Pressure
Authors: Colton R. H. , Brown W. S.
Published: October 2005

Previously, Wright and Colton [J. Acoust. Soc. Amer. 51, 141 (1972)] described a power function between vocal effort and SPL that was concave downward with the knee of the function occurring apparently at the subject's most comfortable effort level. A similar function was noted for effort and fundamental frequency. In this study, a similar paradigm was utilized to explore the relationship between effort and intraoral air pressure. Vocal effort for the CVs /da/ and /ta/ was measured by magnitude estimation and production; intraoral air pressure was sensed with a tube-transducer system. Minimum, most comfortable, and maximum effort levels were also determined. The results show that vocal effort is a power function of intraoral air pressure. Furthermore, the function shapes were very similar to those reported by Wright and Colton; the change of slope tended to occur at the most comfortable effort level. Males tended to show the typical function; females tended to display a more straight function. These results tend to suggest the possible existence of two mechanisms involved in varied effort levels, since air pressure rises more rapidly below comfort level than above.
A Review of Progress and Applications in Acoustic Microscopy
Authors: Kessler L. W.
Published: October 2005

Acoustic microscopy is a relative newcomer to the field of acoustic imaging which will allow the discrimination of micron-size structural detail and will render mechanical microstructure directly observable. Because of the unique characteristics of acoustic wave propagation in materials, potential wide areas of application are anticipated in both the physical and biological sciences. This talk will present a discussion of recent developments in acoustic microscopy techniques and applications. The present efforts to develop experimentally useful systems employ optical methods of sound amplitude detection through various means of coupling. The desired acoustic pattern can be displayed as a hologram or as a conventional image. Further, phase contrast and dark field techniques are also possible. Thus far, resolution better than 10 μm has been reported, and it is reasonable to expect that the resolution will soon be improved to the point of equivalence to optical microscopy, viz., about 1 ωm. Comprehensive investigations into possible applications of acoustic microscopy are somewhat restricted at present because of the unavailability of a suitable instrument; however, during the course of preliminary investigations, various interesting and meaningful contrasts have been demonstrated between acoustic and optical micrographs of the same specimens. These will be discussed in the context of their being the first such comparisons to be made rather than in the context of their being definite applications of acoustic microscopy.
Reliability of Structures under Random Loading
Authors: Heller Robert A.
Published: October 2005

Random loads acting on structures can be placed into two broad categories. Into the first category belong loads with large numbers of repetitions such as those produced. by wind gusts, ocean waves, noise, boundary layer turbulence, fuel sloshing, or rough roads. Such loads are usually characterized by low-amplitude stationary or quasi-stationary random processes. Into the second category belong loads whose appearance is less frequent. Loads produced by sonic booms, earthquakes, ballistic impact, severe maneuver loads, hurricanes, tornadoes, and tsunamis are classic examples. These have short durations, often large amplitudes, and are governed by nonstationary random processes. While the two groups cannot be completely separated, the first types are usually responsible for the gradual deterioration of structural strength and those in the second class may produce ultimate load failures. Structural response to these random loads depends on basic material properties, as well as on the type of structure, connections, and support conditions. Because structural reliability implies a failure-free operating life, the definition of failure becomes an important parameter. Depending on the structure and its usage, partial failures in conjunction with alternate load paths require consideration. In order to achieve current structural failure goals of the order of 10−6 to 10−8, all the above statistically variable conditions should be considered together. Because of the high complexity involved, however, only individual parts of the problem have been successfully handled in the past. Both theoretical and experimental investigations of the complete problem will hopefully be understood in the near future.
Modeling Small Room Responses with a Real-Time Digital Filter
Authors: Curtis T. H. , Berkley D. A. , Bateman T. B.
Published: October 2005

A real-time digital filter system designed for speech processing [D. A. Berkley and T. B. Batemen, Int. Congr. Acoust., Budapest (1971)] has been used to model the response of several small rooms. Finite impulse-response filters corresponding to room transfer-function magnitude and phase were synthesized using (1) frequency sampling [L. R. Rabiner and R. W. Schafer, IEEE Trans. Audio Electroacoust. 19, 200 (1971)] realized with parallel second-order filter sections and (2) time domain design implemented in direct form. Both allow approximately 20 msec of the response in a 3-kHz bandwidth to be modeled in real time. In principle, any response can be modeled using this system by overlap processing (non-real time). Using the real-time filter, we have studied the effects of modifying the spectral and temporal properties of the room impulse response (see Berkley et al., Paper F8). Both design methods work but noise considerations rapidly become important when using frequency sampling. [Some aspects of this paper were orally presented at the 1972 International Conference on Communications, Philadelphia.]
Community Noise
Authors: Bragdon C. R.
Published: October 2005

The magnitude of the existing urban noise problem is presented in terms of its acoustical characteristics and environmental impact. The current status of community noise research, including acoustical as well as social analysis, is summarized. Implicated environmental health effects involving potential hazardous and nuisance responses to community noise are identified. Public as well as political recognition of community noise is compared to other environmental problems. Existing and proposed noise management programs at all governmental levels are assessed in terms of their relative effectiveness, including protecting the public's interest. Presented are examples of a few existing programs that sufficiently address the problem. The current inadequacies and requirements for more active and comprehensive noise management programs are apparent. Effective coordination of environmental program at all governmental levels is also needed. Present governmental policies and their ability to control community noise successfully are discussed, including considerations in establishing standards.
Hazardous Jet Noise Radiation at Schools near Los Angeles International Airport
Authors: Meecham W. C. , Lane S. R.
Published: October 2005

In the first part of a two part study, indoor and outdoor measurements of jet aircraft noise were obtained at seven schools beneath the eastern approach paths to Los Angeles International Airport. At five elementary schools, the jet noise in the schoolyards ranged from 100 to 120 dBC and constituted a high risk of hearing damage for the young children. The frequency of jet aircraft overflights averages 1 per 2 min for a total of over 200 per school day (8:30 A.M.–2:30 P.M.). The corresponding jet noise levels in the classrooms, 80% of which are not air conditioned or acoustically treated, ranged from 80 to 96 dBA, and caused total disruption of the communication and learning processes. An investigation of aircraft operation alternatives indicated that the noise could be reduced by 10 dB or more if engine power were reduced when the aircraft approached the school areas, or if the aircraft approached at higher altitudes and landed further to the west on the unused 6000-ft-long portion of the 12 000-ft-long runways.
Theoretical Interpretation of Recent Experiments of Helicopter Noise Propagation in Urban Areas
Authors: Pierce Allan D. , Kinney Wayne A.
Published: October 2005

In a recent series of experiments jointly conducted by the DOT/TSC, the Coast Guard, and MIT, recordings were made while a helicopter flew over (1) an array of microphones placed in an open field and (2) a similar array placed in the center of a street flanked by tall buildings. The differences between the two sets of data (initially lower, then higher levels for the urban data) is similar to that predicted previously from laboratory scale model experiments by Lyon, Pande, and Kinney [Summary Rep. DOT-TSC-93]. In the present paper, a somewhat detailed, theoretical explanation is attempted based on a geometrical acoustical model modified to include edge diffraction. A general expression is first derived for the effective gain due to building presence when sound is excited by a monochromatic point source. This is then used to find the mean and variance of octave-band filtered broadband noise for random listener location near the buildings and near the center of the street. The data is then discussed in terms of these theoretical predictions.
Liquid Crystals and Broken Symmetry Hydrodynamics
Authors: Lubensky Tom C.
Published: October 2005

A general approach to the determination of the equations governing linearized hydrodynamics in systems with broken continuous symmetries is introduced and applied in detail to nematic liquid crystals. The hydrodynamical mode structure of nematics is obtained from these equations. Application of the above techniques to the determination of the hydrodynamical equations for cholesterics and smectic liquid crystals is briefly discussed. The complete mode structure for these systems is then reviewed. [Supported in part by grants from the National Science Foundation and the U. S. Office of Naval Research.]
The Design of Lenses for Ultrasonic Imaging
Authors: Green P. S. , Eilers G. J.
Published: October 2005

The materials available for the construction of acoustic lenses provide a far wider choice of physical constants than one has in optics. As yet, little effort has been made to design lenses that effectively combine these materials to provide improved imageforming capability. The use of a digital computer for lens design can greatly facilitate such investigations. In this paper we present the results of a study of both simple and compound acoustic lenses, demonstrating the aberrational characteristics and overall merit of lens configurations optimized for a variety of materials and combinations. Also discussed are the effects on image resolution of lens apodization, and the results of experiments with coated acoustic lenses that exhibited considerably reduced surface reflections. [This work has been supported in part by a grant from the National Institutes of Health.]
Fatigue and Crack Propagation under Nonstationary Random Excitation
Authors: Shinozuka M.
Published: October 2005

The prediction of fatigue life of a structure subject to a dynamic stress history is one of the most difficult engineering problems because of the complexity of the fatigue phenomenon, which is extremely sensitive to material property, structural configuration, stress history, environmental conditions, etc. Recently, engineers have come to a realization that for a more reliable prediction of fatigue life, it is of utmost importance to carry out fatigue tests and perform fatigue analyses under the stress history as close as possible to the reality. This has made it necessary to apply the notion of the random process theory to identify the stress history and to establish the relationship between the fatigue life and the stress history thus identified. So far, most work along this line has been concerned with the stress history that is identified as stationary random process. In this presentation, attention will be focused on those studies in which the nonstationarity of the stress history is considered in the fatigue life prediction.
First Passage Problem in Nonstationary Random Vibration
Authors: Yang J. N.
Published: October 2005

In nonstationary random vibration, a problem of considerable practical importance is to determine the probability, called first passage probability, that the absolute value of the structural response passes out of a threshold for the first time, within a specified time interval. A variety of analytical approximations to the first passage probability are described and compared with results of simulation. Emphasis is placed on nonstationary excitations with short duration, such as earthquake, atmospheric turbulence, spacecraft excitation, etc. First passage probabilities for nonstationary envelopes of the structural response are also discussed.
The Reliability and Validity of In-Ear Microphone Measurements of Ear Protective Devices
Authors: Nichols Thomas L. , Swanson J. Bradley
Published: October 2005

A miniature microphone was placed in a subject's ear after the method described by Brammer and Piercy [J. Acoust. Soc. Amer. 52, 1972 180], and its output fed to a spectrum analyzer set to a bandwidth of 100 Hz. The subjects were seated in a semireverberant room into which a white noise field at 95 dB SPL was introduced. The attenuation of three ear covering devices was measured by subtracting the spectrum obtained with the ear cover in place from the spectrum obtained with the subject's ears bare. The repeatability of measurements was examined with both small changes in microphone and ear cover placement. Microphone placement proved to be more critical, although correlation coefficients between measures across days averaged 0.88. Differences between runs measured at selected frequencies between 250 Hz and 7 kHz, generally fell within a range of ±3 dB. Validity was estimated by comparing the microphone data with psychophysical data gathered earlier. The former tended to indicate more attenuation than the latter, though the correspondence between the two was encouraging.
Evaluation of Two Nonlinear Ear Protectors Using a Constant Temporary Threshold Shift Technique
Authors: Ward W. D. , Lupberger A.
Published: October 2005

Ordinary approved methods for assessing the performance of ear protectors are not appropriate for testing nonlinear devices whose reduction of impulse noise is achieved by peak clipping. Instead, the effective protection can be estimated by determining how much more intense a series of pulses must be with the protector in place in order to produce a given temporary threshold shift (TTS). Such tests were made on two commercially available nonlinear devices, using five test subjects. The median effective protection against a 155-dB impulse was about 13 dB for both devices; however, one of these (a complicated mechanism incorporating a valve that is allegedly closed by the force of the impulse) is five times as expensive as the other (an ordinary V51-R-type plug with a metal insert through which a 1/40-in. hole has been drilled). The results are shown to agree with measurements of peak reduction using cadaver ears.
Aerodynamic Noise from Vehicles
Authors: Chanaud Robert C. , Muster Douglas
Published: October 2005

The sources of vehicle noise and their importance relative to aerodynamic noise is given. Using the theory of Lighthill, a summary is given of aerodynamic noise theory and experiment. Following a review of the literature on axial and propeller fan noise and on vehicle cooling fan noise, the present state of the art is described, including present noise reduction approaches. The role of aerodynamic noise in internal and external noise spectra is described. An assessment is made of the present state of knowledge and trends in vehicle design. Recommendations are made for future areas of research.