bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound Absorption in Binary Mixtures of Alcohol and Water
Authors: Madigosky W. M.
Published: October 2005

The excess absorption observed in alcohol-water mixtures is shown to result from a coupling of the sound wave with the long-wavelength spectrum of the composition fluctuations. The fluctuation theory of Ramanov and Shovyev is compared with the theory due to Fixman. It is shown that both theories agree as to the frequency dependence of the excess absorption but differ in predicted magnitude. It is further suggested that the extreme absorption in the case of alcohol-water mixtures is due to an additional interaction between short-wavelength fluctuations and molecules of the two components that form a liquid structure or complex. Experimentally, we have observed a high-frequency absorption or “B” value in excess of that predicted by shear and compressional viscosities. This value also peaks as a function of concentration.
Techniques for the Analysis of Microbarograph Records of Acoustic-Gravity Waves Generated by Nuclear Explosions
Authors: Pierce Allan D. , Moo Charles A. , Posey Joe W.
Published: October 2005

The model based on the generalization of Lamb's edge mode to nonisothermal atmospheres predicts that the pressure oscillation at a large distance from a nuclear explosion has a waveform whose relative shape depends on only two dimensionless quantities, t/TD and TY/TD. Here t is time relative to that of first received peak, TD is a characteristic time which is a functional of the atmospheric sound and wind speed profiles over the line between source and observer, and TY is the time duration of the explosion's blast wave at moderate distances from the burst. The theory accordingly implies that one should in principle be able to measure both TY and TD from analysis of empirical waveforms. However, since the theory is approximate and since the available data are obscured by the presence of ambient noise and the imperfect response characteristics of the recording system, the estimation of these parameters requires some care and statistical methods. Data-analysis techniques based on measurement of distinct features in the waveforms are discussed and applied to data assembled by Donn and Shaw. The general applicability of the single-mode hypothesis is supported by the correlation of such features with numerical calculations.
The Influence of Spatial Separation of Sound Sources on the Vertex Potential
Authors: Butler R. A.
Published: October 2005

The amplitude of the vertex potential (N1P2 component) evoked by alternately presented sounds was studied as a function of the azimuth separation between the sound sources. A 1000- 67-dB-SPL tone served as the standard stimulus. It was located at 270° azimuth and was presented on every odd second throughout 200 sec. A variable stimulus of similar physical characteristics was presented on every even second. Its location, however, was either 270°, 315°, 0° or 90° azimuth. Twenty Ss were tested four times on each combination of standard stimulus-variable stimulus location. The amplitude of the evoked responses summed for 100 standard and 100 variable stimuli differed significantly (p < 0.01) among the various conditions of spatial separation. Response amplitudes were least when the sound sources were near one another. It is suggested that alternately presented stimuli originating close together in space activate a common pool one neurons, thereby promoting habituation. When alternately presented stimuli are widely separated in space, the stimuli from each location activate a different pool of neurons; the habituating effect of repetitive stimuli is reduced.
The Averaged Evoked Response Threshold for Monaural And Binaural Masked Signals
Authors: Edwards Joyce D. , Henderson Donald , Nodar Richard H.
Published: October 2005

The parameters of the averaged electroencephalic response (AER) are well documented for simple listening situations; this experiment was designed to explore the AER to more complex conditions. The AER and behavioral thresholds were measured for five human subjects. A 500-Hz 20-msec tone (with a rise/fall time of 5 msec) and continuous white noise were delivered through headphones for the following conditions: NmSm, NoSo, NoSm, and NπSo. Behavioral and AER masked thresholds were approximately the same for the NoSo condition but averaged about 6 dB poorer for the AER for the NmSm condition than for the behavioral condition. Both the AER and behavioral thresholds for the NoSm and NπSo were of typical threshold differences (5 dB and 12 dB, or better, respectively) than the NmSm and NoSo conditions. The results indicate that: (1) the AER reflects the signal in the presence of noise background; (2) the AER reflects binaural interaction as demonstrated by the MLD; (3) the AER masked threshold is better with binaural presentation (NoSo) compared to monaural presentation (NmSm).
Effects of Stimulus Complexity of the Auditory Evoked Response
Authors: Bothe G. G. , Elfner L. F.
Published: October 2005

Sixty-four subjects were run in an experiment to determine the effect of stimulus complexity on the auditory evoked (Vertex) response. The 760-msec stimulus consisted of 10 bursts of pure tone with 40-msec burst durations and interburst intervals. Stimulus complexity was varied by utilizing tone bursts of different frequencies within the stimulus. Four levels of complexity (1, 2, 5, and 10 frequencies per stimulus) were used. Tone order in the multifrequency conditions was quasirandom, with each frequency represented an equal number of times per stimulus. The frequencies were balanced for loudness. In each condition, 500 stimuli were presented with an interstimulus interval of 1.2 sec. Recording of the responses was by electrodes placed at vertex and mastoid, with a forehead ground. The 500 responses were broken down in a signal averager into 20 averages of 25 responses each. These 20 waveforms were then averaged across subjects within conditions. Results indicate that increasing stimulus complexity produces an exaggerated negative excursion at about 350 msec after stimulus onset. A more rapid habituation of the N1−P2 complex is also present as compared to simpler stimuli.
Rebound and Reverberatory Responses by Low-Frequency Neurons in the Inferior Colliculus of the Kangaroo Rat
Authors: Stillman Robert D.
Published: October 2005

A small number of low-frequency inferior colliculus neurons show, aside from the usual tone-driven response, late discharges which are a function of the time after the stimulus “off.” These late discharges are always preceded by a silent period of 10 to 50 msec, indicating the presence of inhibition and suggesting that the responses are rebound phenomena following inhibition. Occasionally, the rebound discharges are followed by a second silent period and then additional firing. While rebound and reverberatory responses in the inferior colliculus are not of as long duration as those commonly observed in the medial geniculate, their presence indicates that the processes responsible for such activity are intrinsic to both aggregates. If one ignores the rebound and reverberatory discharges, the response of these neurons to tone bursts is indistinguishable from the response of non-rebound neutrons. The rebound and reverberatory discharges, however, are most sensitive to frequency and intensity, but, unlike the early responses, are relatively insensitive to interaural phase. [Research supported by NINDS Post-doctoral Fellowship and NIH grant to George Moushegian.]
Generation and Reception
Authors: Hueter T. F.
Published: October 2005

Development in the art of transducer design and array configuration has been spurred on mainly by two motivating forces: (1) Extensive research in underwater propagation has established the advantages of increasingly lower frequencies for long-range detection and localization of targets and noise sources; (2) the advent of new piezoelectric and structural materials and of solid-state electronic devices has led to substantial improvements in transducer performance with regard to sensitivity, power output, and depth of submersion. Theory has kept abreast of these developments, particularly in handling large arrays with their mutual impedance problems, in pointing to digital multibeam-forming techniques, and in revealing the significance of waveform design to detection performance. A few new concepts were born and have won acceptance during this period. These include the generation of sound by hydroacoustic means, the employment of compliant metal tubes for acoustic focusing and reflection, the exploitation of structural flexing modes for sound radiation, and the use of free-flooded cavity structures as deep submergence sources. As we continue to adapt our sources and receivers to the ocean's transfer functions, noise patterns, and targets—false and true—there will be an increasing need for fundamental research into the acoustic properties of materials and for field tests of experimental acoustic detection systems.
Household Noise Problems
Authors: Baade Peter K.
Published: October 2005

Quietness in the home is everybody's desire but nobody has complete control over it. It requires close cooperation between owners, neighbors, builders, contractors, manufacturers, and municipalities. One of the key problems in this cooperation is the difficulty of communicating acoustical information. Sound-control information needed for mechanical equipment falls into three categories: (1) equipment sound ratings, (2) application and installation data, and (3) acceptability criteria. Industry must accept the responsibility for the first two categories. The most illusive link in the noise-control chain is that between the objective measurement of noise and the subjective reaction of people. As far as equipment purchased by the home owner for use within the home is concerned, the existence of certified ratings will provide him with a basis for a rotational decision. Noise codes and ordinances may be needed for protecting neighbors, but they serve a useful purpose only if they are realistic and written in such a way that they are legally enforceable.
Uses of Glass-Fiber Insulation for Sound Control in Residential Construction
Authors: Sabine Hale J.
Published: October 2005

Glass-fiber insulation in board or blanket form is used in several applications for airborne and impact noise isolation in residential construction. These include (1) sound-absorbing cavity fill for improving the airborne transmission loss of walls and floors, (2) vibration-isolating underlayment in floors and single-stud walls, and (3) finished acoustical materials for absorption of reverberant room noise. The improvement in transmission loss of a wood-stud drywall due to a 3-in. thickness of glass-fiber cavity fill ranges typically from 2 to 10 STC, depending on the degree of structural isolation between the two sides. The improvement is found to increase with thickness of cavity fill, but is virtually independent of density or flow resistance over a wide range. In steel-stud drywalls, glass-fiber board applied between the gypsum board and the stud acts both as a vibration isolator and sound absorber. Improvements of 10 STC are typical. In hard-surfaced wood joist floors, a combination of glass-fiber-board underlayment, blanket cavity fill, and a resiliently supported ceiling yields an over-all improvement of 16 in Impact Noise Rating.
Electron Microscopy (Scanning and Transmission) of Acoustic Damage in the Cochlea
Authors: Lim David J. , Melnick William
Published: October 2005

Guinea pigs were exposed to 300–600 Hz and 1000–2000 Hz octave bands of noise in a sound field measured at 117 dB SPL. Exposure times were 2, 4, 6, 12, and 24 h. Animals were sacrificed immediately after exposure. At least three observations were made which, to our knowledge, have not been previously reported: (1) bleb formation on the sensory hairs; (2) deformation of cuticular lamina of the hair cells; and (3) changes in Golgi's apparatus. We have also observed changes in the Organ of Corti which have been described by others. These include swelling of hair cells, increased lysosome-like bodies, nuclear chromatin aggregation, and vesicular dilatation of the outer hair-cell plasma membrane. Hair cells were observed in differing states of damage varying from simple blebs on the hairs to complete destruction. When there apparently was total destruction of sensory cells, the space previously occupied by the cell seemed to be filled by a supporting Deiter cell. These findings will be illustrated by numerous electron micrographs. [Supported in part under an Air Force contract.]
Automatic Formant Tracking by a Newton-Raphson Technique
Authors: Olive J. P.
Published: October 2005

A wide range of speech investigations requires natural-sounding synthetic speech whose individual acoustic features, such as pitch, formants, and duration, can be varied independently. This paper describes an algorithm for obtaining such synthetic speech by automatically analyzing natural speech to obtain data for the control of a formant synthesizer. The lowest three formants of natural speech were determined by finding simultaneous solutions of the least-square-fit equations by a Newton-Raphson technique. The data obtained from the analysis and pitch data, also obtained automatically, was used for controlling a computer-simulated formant synthesizer. This algorithm was tested for various sentences and speakers, and the synthesized speech was found to be of good quality.
On the Medium from the Point of View of Underwater Acoustics
Authors: Berman Alan , Guthrie Albert N.
Published: October 2005

Twenty years ago, the thermostructure of the ocean was known in moderate detail, while the character of the boundaries could be specified less precisely. The principal deficiency was in the ability to handle a mathematical model of the ocean which would allow a prediction of the acoustical field in great detail. The past twenty years have seen a considerable accumulation of detailed knowledge concerning the geographic and seasonal variation of the medium. Reasonably good specifications of the boundaries are now available, as is an enhanced computational ability, which allows detailed treatment of models that represent the medium in much finer detail. Surprisingly, much remains unknown. The acoustic absorption coefficient in the ocean is known imperfectly and our ability to specify the thermo microstructure is poor. Nonetheless, the intensive effort of many investigators over the last twenty years has yielded a computational capability which now allows a general specification of propagation in relatively great detail. This paper reviews our inventory of information and our ability to handle fine-grained models and outline the deficiencies in our knowledge.
Problems of Sound Reinforcement in Large Halls
Authors: Boner C. P. , Boner C. R.
Published: October 2005

Large halls afford maximum opportunity for acoustical difficulties. High noise level, long-delayed reflections, focusing, sound-equipment limitations, and other factors are present. Program material, “including, but not limited to” everything from motorcycle races and bullfights to famous entertainers using dialect, with symphony as an added attraction, must be satisfactorily accommodated. There is opportunity for operators to misoperate, for press reviewers to devastate, and for local experts well versed in radio and television to improve the sound. Message constraint rarely exists, except in rock music where the levels are constrained to be high. The paper discusses practical measures which have been employed to alleviate some of these difficulties.
Acoustics of Worship Spaces
Authors: Klepper David L.
Published: October 2005

Experience in the last several years has indicated that worship environments can have both high speech intelligibility and high reverberation time. This may be accomplished by architectural means in some situations, but often electronic reinforcement systems are required. There are six basic types of such systems: (1) central, (2) dual central, (3) overhead distributed, (4) pewback, (5) overhead directional distributed, and (6) column distributed, each suited to a specific architectural-acoustical problem. With regard to music, relationships between the choir, organ, and congregation are equally important in the high-reverberation-time cathedral-like spaces and the smaller, more intimate environments. Many aspects important in the over-all design will be discussed and examples will be given.
The Radiation Resistance of a Baffled Rectangular Panel
Authors: Wallace C. E.
Published: October 2005

The radiation resistance of a panel, vibrating in a single mode, is theoretically determined from the acoustic power radiated. The panel is supported in an infinite baffle. The supports include hinges on all four sides and either hinged or clamped supports on two opposite sides with the other sides unsupported. Asymptotic solutions are found and curves covering the entire frequency range are obtained through numerical integration. Well below the critical frequency, the radiation resistance of a panel hinged on all four sides is a minimum for square intranodal areas. By considering a panel or beam either hinged or clamped at each end and vibrating at a given frequency well below the critical frequency, it is found that the ratio of the radiation resistance of the clamped beam to that of the hinged beam is 0.851 for the first mode and 0.711 for the second mode, and approaches 2 as the mode number tends to infinity. For both hinged and clamped supports, the radiation resistance of all modes increases with the beam width-to-length ratio. [Supported by the National Research Council and the NASA Langley Research Center.]
Scattering Attention of Sound in The Lower Atmosphere
Authors: Sutherland L. C.
Published: October 2005

The evaluation of community noise levels from sources such as jet aircraft involves the the prediction of sound-attenuation losses in the atmosphere. The potential significance of scattering attenuation is reviewed, along with theoretical and phenomenological models for scattering attenuation by homogeneous turbulence. Limited experimental field data on scattering attenuation are compared with theoretical predictions to illustrate its potential significance at low frequencies. Recent improvements in the prediction of molecular-absorption losses at frequencies below 1000 Hz are utilized as a basis for estimating the residual scattering loss observed.
Inhibition of the Acoustic Reflex in Subjects Attending to Faint Auditory Signals
Authors: Gunn Walter J.
Published: October 2005

Two experiments were conducted in order to test the Loeb-Riopelle hypothesis that subjects might act to inhibit the acoustic reflex (AR) when listening for faint signals. The results of the first experiment do not demonstrate any significant effect on the AR as a result of listening for faint clicks. In the second experiment, subjects tracked a 250-Hz threshold-level tone before and during AR-eliciting tones in the same ear in one condition, and in the other condition merely remained alert during the AR elicitation. The results were earlier reported as not supporting the Loeb-Riopelle hypothesis, but when considered in terms of the crossed-reflex, they seem to support the notion that subjects do inhibit the AR when tracking a 250-Hz threshold-level tone.
Holographic Interferometry of a Speech-Excited Acoustic Transducer
Authors: Snider Donald L. , Wise Lee A.
Published: October 2005

This paper discusses stone experiments in the analysis of speech utilizing time-averaged holograms of a vibrating transducer being driven by a speech signal. The research is directed toward the use of these holographic interferometry techniques as a tool in the recognition of speech and/or speaker. The experiments have been conducted with various acoustic transducers, including a sonar transducer and several different types of loudspeakers. Only steady-state isolated vowel sounds have been used as test signals to date, but future experiments may include the concatenation of several sounds. The patterns formed by the holographic interferometry method suggests their possible use as a type of voice-signature display analogous to the contour sound spectrogram. Comparisons have been made between several samples of the same vowel sounds for several speakers.
The Preference of Slope Overload to Granularity in the Delta Modulation of Speech
Authors: Jayant N. S. , Rosenberg A. E.
Published: October 2005

A preference study was made to assess the relative annoyance values of slope-overload distortion and granular noise in delta-modulated speech. The delta modulation was performed at frequencies of 20 and 40 kHz, and controlled amounts of the two types of degradation were introduced into samples of a 2-sec utterance. Rankings were obtained for these samples on the basis of paired-comparison preference judgments of nine listeners in a tournament-type strategy. Results indicate that the speech sample exhibiting the minimum degradation on an objective over-all noise-power basis is not a subjectively optimum sample but has a greater overload-to-granularity ratio than the objectively optimum utterance.
Speaker Normalization for Automatic Word Recognition
Authors: Boehm J. F. , Wright R. D.
Published: October 2005

Automatic word-recognition systems typically exhibit marked degradation in performance when used on speakers other than those who contributed the “learn” data. Extension of word-recognition systems to accommodate new speakers usually involves extensive retraining. A procedure which would measure and “adapt” to characteristics of a new speaker would allow for improved recognition rates without retraining. One such procedure has been to measure maxima and minima of formant frequencies and adjust the recognition accordingly [L. J. Gerstman, “Classification of Self-Normalized Vowels,” AFCRL Conference on Speech Communication and Processing Reprints (1967)]. Of particular significance are procedures which involve little or no manual intervention and allow the recognition to remain “automatic.” This paper reports on several approaches, including use of the sample covariance matrix as a purely statistical method, and use of a “phoneme-map” as a more subjective manual intervention method. The various approaches are discussed in terms of degree of recognition improvement, amount of additional complexity, and amount of nonautomatic effort required.
Ultrasonic Flaw Detection in Model Railway Wheels
Authors: Dalvi N. G. , Bray D. E. , Finch R. D.
Published: October 2005

Feasibility studies for detection of flaws on the tread and in the plate of a railway wheel have been made using 14-scale models. With regard to flaw detection on the tread, both attenuation and pulse-echo methods have been employed, using surface waves. The acoustical equipment is similar to that previously described [D. E. Bray and R. D. Finch, J. Acoust. Soc. Amer. 47, 114 (1970)]. Flaws were simulated with machined channels inscribed to different depths on the tread. Changes in the attenuation of a surface-wave pulse with successive circuits of the tread could be detected in the presence of a flaw about 0.005 in. deep. This attenuation has been studied as a function of increasing flaw depth, number of flaws, and location of the flaw with respect to the source. With regard to flaw detection in the plate, some preliminary studies with two-dimensional models of a wheel cross section have been made. Here, the objective was to determine optimum frequency and transducer diameter to minimize rim reflections in favor of plate flaw echoes. [This work was supported by a Department of Transportation contract.]
Reciprocity Calibration of Microphones in High Ambient Pressure
Authors: Sergeant R. L. , Murry T.
Published: October 2005

Research concerning man's ability to speak and hear within ambient conditions of many times normal atmospheric pressure poses special difficulties in calibrating psychoacoustic equipment. In this experiment, a system for obtaining reciprocity calibrations within hyperbaric environments was employed. By means of the reciprocity system, microphone sensitivities were calculated from measures taken with a piezoelectric microphone. Frequencies were 0.1 6 kHz, and conditions of ambient pressure within a helium-filled hyperbaric chamber were equivalent to pressures encountered from surface to 600-ft submersion in sea water (1–19 ata absolute). The results indicate that, at frequencies below 1 kHz, increases in ambient pressure from surface to depths of 600 ft were accompanied by consistent decreases in microphone sensitivity. At 2 kHz, sensitivity did not continue to decrease for pressures equivalent to submergence from 300 to 600 ft. Resultant corrections to the calibrated microphone for increases in ambient pressure permit accurate measures to be made of stimuli for psychoacoustic experiments, and precise acoustic analyses can be made of speech produced under hyperbaric conditions.
Pressure Radiations from an Infinite Two-Layered Elastic Plate with Point- and Shear Force Excitations
Authors: Lai J. L.
Published: October 2005

Pressure radiations generated from a two-layered elastic plate excited by time-varying point and shear forces are obtained analytically. The plate, made of two different isotropic and homogeneous materials of uniform thickness, is bounded on one side by a fluid medium and another side by a vacuum. Both the fluid and the plate are assumed to be infinite in extent. The effects of transverse shears and rotary inertias in both layers are included in the equations governing the plate motion. The solution is obtained with the aid of Hankel transforms for spatial coordinate and Laplace transform for time variable. Saddle-point technique is used to carry out the inverse Hankel transform for farfield radiation. Numerical results for pressures generated by time-harmonic point or shear force are presented.
Sound Intensity in Evanescent Waves
Authors: Goodman R. R. , Bunney R. E.
Published: October 2005

During the past few years, several scattering experiments, using cylinders and spheres, have demonstrated the complexity of the scattered field produced by an elastic scatterer. The scattered field has been calculated by both a modal and a ray approach. The latter gives a clearer physical picture of what is dynamically occurring during the scattering at sufficiently small wavelengths. There is a question, however, as to whether or not Rayleigh-type waves moving around the cylinder are necessary to explain the periodic directional scattered waves that are observed in pulsed experiments. In an effort to resolve this point, a study of the intensity of an evanescent wave on a semi-infinite elastic medium bounded by an ideal fluid was undertaken. The intensity of the evanescent wave as a function of the angle of incidence has been calculated in an effort to see if there is an increase in intensity of the evanescent wave near and at the critical angle for Rayleigh waves. These results will be given. Departures from flat boundaries and the application of these results to scattering phenomena will be discussed.
New Evidence on the Persisting Nuclei
Authors: Turner William R.
Published: October 2005

The laboratory evaluation of the acoustic microbubble spectrum analyzer has disclosed several types of persisting microbubble phenomena as a varying abnormal attenuation with frequency. Microbubble populations are detected in a tank filled with tap water only sporadically and may be influenced significantly by barometric pressure. Distilled water open to the atmosphere can become rapidly charged with persisting microbubbles. An increase of temperature or a reduction of local pressure can be used to expand microbubbles into the detection range of the instrument. For limited excursions of temperature and pressure, the change in attenuation is reversible, indicating a stability range for persisting microbubbles. The observed attenuation spectra include examples of sharp peaks, which indicate a narrow range of microbubble size, and broad peaks, which indicate a distribution of sizes. [This work supported in part by the Office of Naval Research.]
Temporal Integration at 125 Hz
Authors: Campbell Richard A.
Published: October 2005

An apparent lack of temporal integration for a 125-Hz signal was interpreted as having implications for the neural coding of periodicity pitch by Campbell and Counter [J. Acoust. Soc. Amer 45, 691–693 (1969)]. Watson and Gengel [J. Acoust. Soc. Amer. 46, 989–997 (1969)] suggested, rather, that the failure to observe temporal integration at 125 Hz was due to the spread of energy at the shorter durations upward into frequency regions of greater sensitivity. Consideration of the data mentioned above and additional data gathered at 125 Hz with durations of 30, 100, and 300 msec and rise/fall times of 1 and 5 msec presented with and without a noise (160 to 360 Hz), intended to minimize the upward spread of energy, indicate that the apparent lack of integration was due to the upward spread of energy. The rise/fall time does, however, seem to play a crucial role in this upward spread of energy rather than the short durations, per se. Furthermore, for higher frequencies, rise/fall times do not seem as critical.
Forced Longitudinal Vibrations of Prismatic Slender Bars with Distributed Quadratic and Equivalent Viscous Damping
Authors: Wilkinson A. D. , Michalopoulos C. D.
Published: October 2005

Forced longitudinal vibrations of a prismatic slender bar with quadratic skin damping and equivalent viscous damping are considered. The bar is assumed to be free at one end and subjected to sinusoidal motion at the other. The differential equation of motion for the case of quadratic damping is solved numerically by the method of characteristics. Frequency-response curves are given for several values of the nonlinear damping coefficient. The equivalent linear system is analyzed by Laplace transforms, and the results are compared with those for the nonlinear system. The equation of motion is linearized by equating the energies dissipated per cycle by quadratic and viscous damping.
The Use of Moiré Fringes in Investigating Surface-Wave Propagation in Monolayers of Soluble Polymers
Authors: Scott J. C. , Stephens R. W. B.
Published: October 2005

In this use of the Moiré, the passage of the traveling surface wave displaces the fringes perpendicular to their rest direction by an amount which is proportional to the slope of the wave at each point of the wave train. From a picture obtained by electronic flash, both damping and wavelength can be evaluated. With polymer monolayers the system shows surface elasticity, and the damping of the waves is greatly increased compared with that for a pure liquid owing to the surface tension gradients. This high dissipation is attributable to the existence of longitudinal surface waves, a resonance phenomenon occurring at surface elasticities for which the velocities of the two types of waves are equal. The fundamental similarity shown between members of the same homologous series suggests that the surface properties are related to short segments of polymer molecules rather than to the whole molecules.
The Use of High-Power Ultrasonics (Macrosonics) in Studying Fatigue in Metals
Authors: Mason Warren P. , Mac Donald Douglas E.
Published: October 2005

High-power ultrasonics has been a useful tool in studying fatigue in metals, since a large number of cycles can be obtained in a small time. In the case of brass and iron, the mechanisms appear to be different, since at the high frequencies fatigue occurs in isolated regions, whereas at the low frequencies the slip is generally spread over the grains. The same mechanism can be produced at high frequencies by going to higher temperatures. In iron, the stress required for fatigue at higher frequencies is considerably less than for low frequencies. Recent measurements in titanium have shown that the required stress is about the same for high and low frequencies. The crack propagation velocity, however, is much faster at the ultrasonic frequencies. This was proved by striation measurements with a scanning electron microscope. A striation reflects the fact that the crack propagates under a different stress on one-half of the cycle than it does on the other half. Hence, by counting the number of striations, the velocity can be calibrated; thus the high-frequency fracture is not only localized, it is virtually catastropic in the localized area. [Supported by the Fatigue and Structural Reliability Institute under a contract with the U. S. Navy Office of Naval Research.]
Roadside Noise from the Interaction of a Rolling Tire with the Road Surface
Authors: Hayden R. E.
Published: October 2005

As noise from ground transportation vehicles continues to arouse public concern, physical understanding of the various noise sources becomes essential in seeking means to quiet vehicles. Tires are one of the perdominant noise sources on trucks and automobiles. This study analyzes the various mechanisms by which noise can be generated by the interaction of a rolling tire with the roadway surface. Physical models are presented for the “air pumping” vibrational and aerodynamic noise mechanisms, which are then rank-ordered in sound-producing capability for several classes of vehicles. Results of limited experiments are discussed, and measured data are interpreted in terms of the physical models.
Pitch Variability and Its Linguistic Interpretation
Authors: Atkinson J.
Published: October 2005

Fundamental-frequency contours for simple sentences with various prominence placement and intonation contours were examined to determine variation in pitch for one speaker over an 8-week period. These data were compared with the speaker-to-speaker variation of four other speakers producing the same sentences. The results show that fluctuations both in absolute frequency and in range of excursion are as great in a single speaker as those pooled over four different speakers. The only consistent factors were (1) that syllabic prominence always yields a pitch rise, (2) that questions always have a terminal pitch rise, (3) that statements always have a terminal pitch fall, and (4) there is a consistent interaction between various prominence patterns and sentence types. The range of variation in level and extent of pitch rises allows only a binary distinction to be made of ± Prominence and ± Breath Group. Finer distinctions seem to carry no reliable linguistic information even within the same speaker.
PARAFAC: An “Explanatory” Factor Analysis Procedure
Authors: Harshman Richard A.
Published: October 2005

Simple structure and other common principles of factor rotation do not in general provide strong grounds for attributing explanatory significance to the factors which they select. In contrast, it is shown that an extension of Cattell's principle of rotation to proportional profiles (PP) offers a basis for determining explanatory factors for three-way or higher-order multimode data. Conceptual models are developed for two basic patterns of multimode data variation, system- and object-variation, and PP analysis is found to apply in the system-variation case. The generalized PP model provides the basis for a program called PARAFAC (for parallel factors). This program is demonstrated to give unique “correct” solutions with oblique nonsimple structure and even nonlinear factor structures. A series of tests, conducted with synthetic data of known factor composition, provides data on the minimal necessary conditions of uniqueness and the properties of the analysis procedures when these minimal conditions are not fulfilled. PARAFAC has been applied to several different sets of real data with meaningful results (as reported elsewhere in this meeting).
Prediction of In-Flight Fluctuating Pressure Environments
Authors: Robertson J. E.
Published: October 2005

In recent years, considerable effort has been devoted to the study of unsteady flows over the surface of many different vehicles—aircraft, launch vehicles, underwater craft, etc. The fluctuating pressures resulting from unsteady flows can be an important source of vibration and sound and, thus, significantly affect the performance and environments of these vehicles. Fluctuating pressures may arise from several modes of disturbances; however, they are most often introduced by the passage of turbulence over the external surface. Particular phenomena, which can be of significance in various circumstances, include attached boundary layers, separated boundary layers, oscillating shock waves (often referred to as shock-boundary layer interaction), protuberance flows, jet impingement, cavity response phenomena, and base or wake flow. Many of the phenomena above involve forms of turbulent separated boundary layer flows, and the paper is centered around a description of these. The extensions of the available data to unusual geometries, such as space shuttle, will be discussed and examples of the accuracy fo such extrapolation shown. One of the principal problem areas for aircraft and space vehicles is in the transonic speed range, and a major portion of the paper will be devoted to a discussion of the transonic fluctuating pressure environments. Based on test results from many sources, prediction methods for the various unsteady flow environments are suggested. Key features of the present paper are the bringing together of data from disparate sources, combining the results to show general trends for the various unsteady flow phenomena, and, based on the combined results, the development of prediction methods.
Measurement of Acoustical Transients in the Atmosphere
Authors: Cook Richard K. , Bedard Alfred J.
Published: October 2005

Volcanic explosions, the flight of aircraft, auroral motions, and various other processes give rise to transient sound pressures, some of which are propagated to long distances through the atmosphere. Detection by means of an infrasonic microphone in the presence of local wind noise requires an electroacoustical system having a relatively narrow bandwidth; therefore, a characteristic of the transient sound pressure must be deduced from “imperfect” electroacoustical data. The methods and analytical procedures now in use for reconstructing the transient sound pressure will be exemplified with data obtained on several types of atmospheric transients.
Perception of Dichotically Presented Stop Consonants in Relation to Amount and Kind of Information Shared by Ears
Authors: Shankweiler D. , Studdert-Kennedy M. , Pisoni D. B.
Published: October 2005

Earlier experiments had shown that dichotically presented stops are more often identified correctly when they share place of production (e.g.,/ba, pa/) or voicing (e.g., /ba, da/) than when neither feature is shared (e.g., /ba, ta/). We interpreted this as further evidence for the perceptual reality of phonetic features. It is possible, however, that the advantage of sharing a feature has an auditory rather than a phonetic basis. We therefore compared the increments due to feature sharing, for synthetic stop-vowel syllables in which formant transitions were the sole cues to place of production, under two experimental conditions: (1) when the vowel was the same for both syllables in a dichotic pair, as in our earlier studies, and (2) when the vowels differed. If the increment in performance due to sharing place is not diminished when vowels differ (so that formant transitions do not coincide), we can conclude that it accrues after the process of feature extraction and therefore has a phonetic rather than an auditory basis. [Research supported in part by grant from NICHD.]
Sum Frequency Parametric Array
Authors: Willette J. G. , Muir T. G.
Published: October 2005

The nonlinear interaction of two time-harmonic spherical waves to produce a radiation whose frequency is equal to the sum of the frequencies of the carriers is considered in terms of the farfield amplitude and directivity of each carrier. The theory developed closely parallels that for the difference frequency radiation in that the derivation involves an integration of the source strength density with an appropriate Green's function. The results are compared to experiments done in a fresh-water lake with a 3-in.-diam piston projector driven at frequencies of 418 and 482 kHz. The amplitude and azimuth response of the 900-kHz sum frequency radiation was measured as a function of range. [This work was sponsored by the U. S. Navy Office of Naval Research.]
Contribution of the Cricothyroid Muscle to Vocal Frequency and Intensity
Authors: Shipp Thomas , McGlone Robert E.
Published: October 2005

A bilateral superior laryngeal nerve block was performed on a normal adult male subject. The effectiveness of the anesthesia was monitored by emg electrodes in the cricothyroid muscles. Before and at 15-min intervals after anesthesia, the subject performed tasks assessing his total fundamental frequency range and over-all intensity range at high- and low-frequency phonation. In the first procedure, anesthesia was incomplete although it succeeded in reducing the highest frequency by 15 semitones and attenuating the dynamic range in high-frequency phonation by 13 dB. The implications of these findings to other laryngeal muscle studies will be discussed.
Vocal Tract Size Normalization in the Perception of Stop Consonants
Authors: Rand T. C.
Published: October 2005

Synthetic consonant-vowel syllables representative of large and small vocal tracts were presented to listeners for identification. Ten points on the frequency scale were chosen as initial values for the second formant transitions. Subjects identified the initial consonant as [b], [d], or [g]. The results indicate that place of articulation boundaries are shifted upward for small vocal tract stimuli. That is, listeners perceived the place feature for voiced stop consonants by interpreting second formant transitions with respect to vocal tract size information conveyed by the syllables. The results are interpreted as evidence for the existence of normalizing mechanisms that influence consonant perception. This agrees with a motor theory of speech perception whereby the recipient of an acoustic speech signal reconstructs the speaker's articulatory maneuvers.
A Method for Analyzing Vocal Jitter
Authors: Hollien H. , Michel J. F. , Doherty E. T.
Published: October 2005

The purpose of this research was the development of a methodology for valid reliable measurement of laryngeal jitter during sustained phonation. We undertook both to develop and evaluate an appropriate procedure and to provide preliminary data on the degree of jitter present in vocal signals of normal larynges. The method utilized an ultrahighspeed photographic technique for measuring cycle-to-cycle variations in acoustic signals. Validation was accomplished by measurement of three different computer-produced (LADIC) synthetic signals of 65 consecutive cycles; each was programmed for predetermined wavelengths. The programmed values were compared with the measured values and extremely high correlations were obtained. Secondly, films and recordings were made while four healthy male subjects (aged 21–37) phonated the sustained vowel /a/ at each of four frequencies which were based on their phonational ranges. Although our measurements on human subjects failed to support the contention of Weber's law that an increase in jitter characteristically accompanies increase in fundamental frequency, we can conclude that (1) the methodology developed provides a valid means of measuring variations in quasiperiodic acoustical signals and (2) that we have been able to provide some tentative data concerning the amount of jitter that can be expected in the sustained phonation of normal male voices.
Monitoring Soft Palate Movements in Speech
Authors: Ohala John J.
Published: October 2005

A simple photoelectric device has been constructed which permits easy monitoring of soft palate movements in speech. Since its output signal cannot easily be calibrated, it is most useful for detecting the timing of such movements and the relative rather than the absolute amount of velopharyngeal opening. Using it, it has been possible to verify others' findings that: (1) The soft palate is lowered more during vowels preceding a nasal consonant than it is during vowels following a nasal consonant. (2) The soft palate begins to lower for an upcoming nasal consonant as soon as it can, i.e., as soon as it is no longer required to be closed for an obstruent. (3) Other things being equal, the soft palate is typically lowered during the production of so-called low “oral” vowels such as [a]. [Supported by the National Science Foundation.]
The Direct Measurement of Loudness Levels of Complex Sounds
Authors: Milner P. , Allen R. G. , Torick E. L. , Bauer B. B.
Published: October 2005

Sixteen typical 1-sec sound segments from a broadcast program, including speech, music, and noises were measured with a loudness level monitor [IEEE Trans. Audio Electroacoust. AU-15, 178–182 (1967)] and with a sound level meter using A-, B-, and C-weighting networks. The actual loudness levels of the 16 sounds were determined by loudness balance against a 1000-Hz centered 13-oct band of noise. The mean absolute deviation of the loudness level monitor readings from the actual loudness levels was 1.1 phons. The mean absolute deviations for the sound level meter were, for A-weighting, 9.1 and 5.7 dB; for B-weighting, 8.4 and 4.8 dB; and for C-weighting, 5.8 and 3.2 dB, for the slow and fast meter settings, respectively.
Speech Modulated White Noise
Authors: Katz S. J. , Berry R. C.
Published: October 2005

A variety of speech stimuli—vowels in an h_d context, monosyllabic words, and sentences—were used to modulate a white noise carrier. The speech stimuli were first recorded at a conversational level (approximately 70 dB SPL) then envelope sampled. The output of the envelope sampler was then led to the Y terminal of a Philbrick 4452 multiplier and a white noise carrier was led to the X terminal. The output (speech modulated white noise) was then tape recorded. Twenty-five normal-hearing subjects heard the experimental tapes first as recorded, then as speech modulated white noise, and finally as speech modulated white noise after three training periods. The training periods consisted of short paragraphs of speech modulated noise. The experimental lists were randomized across subjects and conditions. The percentage of words correct for each type of stimuli for each condition was calculated and analyzed using an analysis of variance for matched groups. Results and implications will be discussed.
Vertical Hydrophone Calibrator for Laboratory Use
Authors: Abbagnaro L.
Published: October 2005

A vertically oriented calibrator has been developed for use with gradient and pressure hydrophones. The calibrator is comprised of a water-filled tank suspended to permit motion in the vertical direction. A mechanical drive generates oscillatory motion in the vertical axis and produces pressure and velocity standing waves suited for the calibration of pressure and vertically directed gradient hydrophones. A description of the calibrator and the measuring techniques utilized are discussed.
Thermally Induced Pressure Changes in a Closed Air Volume: An Application to Infrasonic Microphone Design
Authors: Bedard Alfred J. , Hubbard Elizabeth K.
Published: October 2005

Introduction of controlled temperature changes in a closed gas volume is one method of producing reference pressure changes. Devices used for the thermal production of pressure changes have been designated thermophones and operated as primary standards for audio microphones. We have adopted this nomenclature, although in our concept of use we violate a basic assumption upon which past thermophones have been designed. The concept of design is described and experimental measurements are presented. An application as a secondary calibrator for use with infrasonic microphones is discussed.