bluuebunny/crossref_metadata_2025 huggingface dataset:
The Hunting of the “Quark” in Speech Production: Further Evidence from Speech Errors
Authors: Fromkin Victoria A.
Published: October 2005

The search for “basic building blocks” has characterized the aim of many scientists, whether these fundamentals are the physicists' “quarks” or the phoneticians' basic behavioral units. Speech-error data provide evidence that different kinds of units are found to be organized into levels, which levels may correspond to steps in the serial ordering of behavioral events. Any model of this process which considers the phonemic segment as the basic “spark” or “queach” (i.e., speech quark) cannot account for the kinds of lapsūs linguae which occur. But a model which includes only the smaller-sized units, called “distinctive features” by linguists, will also be shown to be inadequate. While such “features” must be afforded an independent status at one link in the speech chain, they are dependent on segment-sized units at an earlier stage. The paper discusses the kinds of features which must be posited and attempts to show that these are related to but not identical with the phonologists' “distinctive features.”
Markov Models for Phonetic Text
Authors: Neuburg E. P.
Published: October 2005

The classical statistical models for phonetic text view phonemes as states of a Markov chain of some low order. There is a model-building method which produces models that lie between these classical models and the combinatorial model of O'Connor and Trimm. To produce the new models, one hypothesizes the existence of an underlying Markov chain of low order with some small number n of states, and assumes that the probability distribution of phonetic symbols is a function of the state of the underlying chain. Given n, the model-building method involves a computer hill-climbing procedure on a corpus of phonetic text to find the maximum-likelihood model for that text and that n. This paper describes the method and the results of a large number of ascents on a certain corpus of text. The models developed show strong linguistic features; for example, for text segmented only by silences between phoneme strings, the vowels, consonants, and boundary symbols are statistically identified with 15% errors. With text segmented into syllables, identification is essentially perfect.
Automatic Detection of Constituent Boundaries in Spoken English
Authors: Lea Wayne A.
Published: October 2005

The F0 contours of texts spoken by several talkers were studied and successfully associated with boundaries of major grammatical constituents. For one talker, a significant F0 rise (usually preceded by an F0 fall) occurred at every syntactically predicted major constituent boundary, except NP-Verbal boundaries. Boundary positions were adjusted to account for the delay in F0 rise when constituents began with unstressed syllables. Falling (“Tune 1”) F0 contours and pauses clearly marked the boundaries of both embedded and matrix sentences in such spoken prose. Phonetically dictated pitch rises at the onsets of voicing [M. Haggard, S. Amber, and M. Callow, J. Acoust. Soc. Amer. 47, 613–617 (1969)] had to be distinguished from rises due to constituent boundaries. A computer program was implemented to detect automatically the major constituent boundaries based on such F0 patterns. Results are reported, talker dependencies are discussed, and implications for speech recognition and perceptual modeling are outlined. [This research was supported in part by the Air Force Cambridge Research Laboratories.]
The Temporal Realization of Morphological and Syntactic Boundaries
Authors: Lehiste Ilse
Published: October 2005

This paper is concerned with the effect of morphological and syntactic boundaries on the temporal structure of spoken utterances. Two speakers produced 20 tokens each of three sets of words consisting of a monosyllabic base form, disyllabic and trisyllabic words derived from the base by the addition of suffixes, and three short sentences in which the base form was followed by a syntactic boundary, this in turn being followed by a stressed syllable, one unstressed syllable, and two unstressed syllables. The sentences thus reproduced the syllabic sequences of the derived words. The duration of words and segments was measured from oscillograms. The manifestation of morphological and syntactic boundaries is discussed, and some implications of the findings relative to the temporal programming of spoken utterances are considered.
Comparison of Controlled and Uncontrolled Normal Speech Rate
Authors: Gregorski R. , Shockey L. , Lehiste I.
Published: October 2005

Temporal studies of speech have employed two methods for elicitation of speech rate: (1) controlled, i.e., externally induced through the use of a pulsating beat, and (2) uncontrolled, i.e., internally generated by the subject with the instruction to maintain a constant rate. The comparability of these techniques for a normal speech rate was the concern of this experiment. A word and a sentence were repeated 150 times each using both methods. Comparisons of durations of pauses, segments, syllables, and words were made. The results indicate that for normal speech rate there are no significant differences between the two elicitation techniques.
The Perception of Subphonemic Phonetic Differences
Authors: Bond Z. S. , Lehiste I.
Published: October 2005

In a preliminary study, D. B. Fry [“Reaction time experiments in the study of speech processing,” Progress Report, Phonetics Laboratory, University College, London (June 1968)] discovered that he was able to discriminate between monomorphemic and bimorphemic words of identical phonemic shape, such as lax versus lacks. In this study, 10 such assumedly homophonous word pairs were tested for subjects' ability to identify them. Ten productions of each member of the pair (for a total of 200) were presented for identification in random order. When total scores for each word pair were considered, subjects were unable to identify any of the word pairs correctly at a statistically significant level. However, in the case of some individual productions of the “homophone” pairs, subjects were extremely consistent in how they labeled the words. The productions which were most consistently labeled were analyzed in order to determine what acoustic cues the subjects were employing. Apparently, subjects are able to recognize certain acoustic cues that are sometimes considered subphonemic. That these cues are not linguistically significant is indicated by the fact that besides correct identifications, the subjects also produced equally consistent mislabelings.
Relation of Syllable Boundaries to Vowel Durations
Authors: Barnwell Thomas P.
Published: October 2005

It is a well-known phenomenon of English that vowels are longer before voiced consonants than unvoiced consonants. It was hypothesized that, if a syllable boundary could be placed between a vowel and its following consonant, the effect of the consonant on the vowel's duration would be greatly reduced. Ten subjects were asked to read 60 words in isolation. Each word contained two syllables with stress on the first syllable, and the first vowel was always /i/. In each case, the vowel was followed by one of the six English stop consonants. The words were divided into three groups: (1) those where there was general agreement among subjects that the syllable boundary followed the vowel, (2) those where there was general agreement that the syllable boundary did not follow the vowel, and (3) those for which there was no agreement on the location of the syllable boundary. Vowel durations were measured and plotted, and the results supported the original hypothesis.
Vowel Durations in Multisyllabic Words as a Function of Phrasal Context
Authors: Allen Jonathan , Barnwell Thomas P.
Published: October 2005

In a previous study, it was found that vowel durations could be predicted for monosyllabic words in three-word phrases as a function of the vowel, following consonant, prepausal position, and syntactic function. The present study extends these results to multisyllabic words. For closed and open syllables, it is shown that the effect of syllable position does not affect the vowel duration, but that the greater the number of syllables, the shorter the vowel. A technique is described wherby each syntactic role can be assigned an equivalent number of syllables, so that the effect of syntactic function and number of syllables can be described by the same parameter. Models are devised for stressed vowels, /∂/, and other unstressed vowels.
Factor Analyses of Format Frequencies
Authors: Lindau Mona , Harshman Richard , Ladefoged Peter
Published: October 2005

The exact relationship between the phonetic quality of a vowel and its formant frequencies has never been stated, because it has not been possible to account for the variations due to the personal quality of a speaker. We have analyzed the fundamental and first three formant frequencies of the eight primary cardinal vowels as spoken by 11 phoneticians using the PARAFAC procedure (Harshman, this meeting). The results were first interpreted as demonstrating three factors which corresponded to the three traditional phonetic (auditory) parameters “tongue height, tongue fronting, lip rounding.” In these vowels, “tongue fronting” and “lip rounding” co-vary. To separate these two factors, an analysis was conducted of a subset of Swedish vowels which included front rounded vowels. A factor corresponding to “tongue height” was still evident. The other two factors were not so easily interpretable. A possible interpretation of one of these two factors related it to to the Jakobsonian feature “compact.”
Auditory Localization: The Role of the Lateral Lemniscus
Authors: Casseday J. H. , Neff W. D.
Published: October 2005

The effects of unilateral and bilateral transection of the lateral lemniscus upon the cat's ability to localize sound were investigated. Five normal cats were trained to localize noise pulses, and their thresholds for minimal detectable angle (localization thresholds) were determined. One lateral lemniscus was then transected. After recovering from surgery, the animals were tested for retention of the localization habit and, after retraining, localization thresholds were determined again. In a second operation, the remaining lateral lemniscus was transected, and the animals were tested a second time for retention of the localization habit. These successive operations had the following behavioral consequences: After unilateral transection of the lateral lemniscus, all animals failed to retain the localization habit but quickly relearned to localize; their localization thresholds were increased. After bilateral transection of the lateral lemniscus, all animals were unable to relearn to localize. Further auditory testing demonstrated that these bilateral cases could learn an avoidance response to a sound signal. Electrophysiological results, obtained after behavioral testing was completed, showed that evoked responses to auditory stimuli were absent at the cerebral cortex. Anatomical evidence indicated that the lateral lemniscus was transected in all cases. [This research was supported by the National Science Foundation.]
Binaural Reverberatory Responses in Medial Geniculate
Authors: Weiss I. P.
Published: October 2005

Neurons in lower auditory nuclei generally respond for a period no longer than the duration of the stimulus. Medial geniculate neurons that responded in such fashion fell into two categories: those responding with one or two spikes to the onset and those responding with a secondary burst as well, which terminated abruptly at the stimulus offset. The latter type evidenced complex binaural interaction. Other neurons showed response durations longer than stimulus durations. These responded with an onset burst followed by reverberatory volleys whose duration was independent of stimulus duration. Changes in the stimulus caused independent variations in the characteristics of the onset and reverberatory responses. Inhibitory influences lasting for several hundred milliseconds are partially responsible for reverberation, and level of anesthesia was shown to be an important parameter. Finally, some neurons were found to respond to the first five or six stimuli of a repetitive train, failing to respond again unless a stimulus parameter was varied. The reverberatory medial geniculate responses may be related to various psychophysical phenomena. [Supported by U. S. Public Health Service grants to G. Moushegian.]
A New Theory of Cochlear Organization: Pattern Recognition by Cross Correlation on an Addressed Exponential Delay Line
Authors: Nieder P. C.
Published: October 2005

In this model, the rate of firing of afferent fibers is influenced by depolarization current from directly contacted inner hair cells—but a gating effect is exerted by the separate system of control fibers addressed to the outer-hair-cell region. Control fibers gating the afferents synapsing with a given inner hair cell constitute a pattern-recognition network for a narrow frequency band. Because of the exponential delay, the wave patterns for all frequencies are congruent, differing only in longitudinal placement along the basilar membrane: hence, for the range of midfrequencies, a single pattern-recognition configuration is needed—requiring only reproduction at each of a sequence of inner hair cells. For mid- and low frequencies, the pattern-recognition procedure essentially constitutes a running cross correlation making use of both excitatory and inhibitory control fibers and a frequency prefiltering control-fiber excitation interaction which also is dc compensating. For frequencies too high for unit time locking, traveling wave envelopes are detected. [Supported in part by NINDS.]
Response of Primary Auditory Neuron to Human Speech
Authors: Goldstein Allan J. , Mundie J. Ryland
Published: October 2005

The auditory system of guinea pigs has been tested using human speech as a source of a complex signal. Data from single primary auditory-nerve fibers have been statistically analyzed with a computer, generating a poststimulus pulse occurrence histogram. The histograms have been compared to displacement patterns of the basilar membrane produced by an electronic analog of the cochlea responding to the same speech signal. Displacement of the basilar membrane in one direction causes an increased probability of spike occurrence; displacement in the opposite direction causes decreased probability of spike occurrence. There is a high degree of time-locked correspondence between the instantaneous probability of spike occurrence and the instantaneous magnitude of basilar-membrane displacement throughout the duration of the complex stimulus. Location along the analog basilar membrane at which the displacement pattern corresponds to the neural histogram is a function of the characteristic frequency of the neutron. This experiment (1) confirms the accuracy of the electronic analog cochlea (Santa Rita Technology, Inc.) and (2) demonstrates that the information conveyed by a primary neuron is displacement of the basilar membrane as a function of time.
Response of Auditory Neurons to Intensity Increments
Authors: Smith Robert L.
Published: October 2005

Single units in the cochlear nuclei of anesthetized Mongolian gerbils were studied. Stimuli were tones at unit's best frequency and response firing rates were determined from PST histograms. The units under consideration typically showed an onset peak and decay to steady firing rate in response to 300-msec tone bursts. The tone bursts served as pedestals upon which step intensity increments were placed. In response to the increments, units showed a jump in firing rate. The time of occurrence of the increment was varied relative to the onset of the pedestal. The maximum firing rate reached in response to the increment was found to be relatively independent of the time of occurrence of the increment. Thus, both the absolute and the relative change in firing rate caused by the increment increased as a function of time relative to the onset of the pedestal. The effect occurred over a wide range of increment and pedestal intensities and could not be attributed to saturation of firing rate. It may be related to the psychophysical ability to detect more easily intensity increments during, rather than at, the onset of tone pedestals.
Combined Effects of Recovery Period and Stimulus Intensity on the Human Auditory-Evoked Vertex Response
Authors: Nelson D. A. , Lassman F. M.
Published: October 2005

Averaged auditory-evoked vertex responses were obtained from eight normal-hearing female subjects in response to 32 monaural 1000-Hz tone bursts at 30 randomly presented combinations of recovery period (interstimulus interval) and stimulus intensity (sensation level). From curves describing N1−P2 peak-to-peak amplitudes, an equation was derived that describes the combined effects of recovery period and stimulus intensity on evoked response amplitude. The results showed evoked response peak-to-peak amplitude to be a dual function of both recovery period and stimulus intensity. At a given stimulus intensity, evoked response amplitude was a logarithmic function of recovery period. At a given recovery period, evoked response amplitude was a power function of stimulus intensity. The combined effects of recovery period and stimulus intensity produced equal ratio changes in the slope and the intercept of the recovery function with equal ratio changes in stimulus intensity.
The Effects of Simultaneous Presentation of Different Frequencies on the “V” Potential
Authors: Butler Robert A.
Published: October 2005

The amplitude of the “V” potential (N1P2 component) was measured when 250 Hz and 8000 Hz, judged equally loud, were presented singly and simultaneously in the following manner: (1) both frequencies to left ear; (2) both frequencies to both ears, and (3) 250 Hz to left ear, 8000 Hz to right ear. A larger response amplitude was found consistently when the different stimuli were presented simultaneously. Additional tests were conducted in which the same frequency (250 or 8000 Hz) was presented binaurally. These always resulted in V potential smaller than those evoked by simultaneous presentation of different frequencies. The finding suggests that one population of neurons activated by 250 Hz and one activated by 8000 Hz contribute independently to the V potential.
Preliminary Experimental Investigation of the Simple Source Theory for Jet Noise
Authors: Scharton T. D. , Meecham W. C.
Published: October 2005

One of the authors [J. Acoust. Soc. Amer. 30, 318 (1958); Aerodynamic Noise Symp., Loughborough Univ. of Technol. (1970), Paper A7] and H. S. Ribner [Advan. Appl. Mech. 8, 103 (1963)] have proposed a simple source theory for jet noise. The simple source, in the simplest form of the theory, is proportional to the second time derivative of the hydrodynamic pressure within the jet. Using the working hypothesis that the correlation length (eddy size) for a region of fluid radiating sound at frequency f is inversely proportional to the frequency, we derive that the ratio of the spectrum of the radiated sound power W(f) to the spectrum of the fluctuating hydrodynamic pressure in the jet Spo(f) is W(f)/Spo≃π4(ρc)−1α2D2M4(f/fs), where ρ is the fluid density, c is the speed of sound in the ambient fluid, α is the turbulence intensity, D is the jet nozzle diameter, M is the Mach number, and fs is the Strouhal frequency. The theoretical values of the ratio are compared with data measured with a small turbojet engine and with a model jet at the UCLA Sonic Research Laboratory.
Direct Correlation between Flow Field and Radiated Sound of a Jet
Authors: Lee H. K. , Ribner H. S.
Published: October 2005

A direct correlation between the flow and noise of a jet—between the “cause” and the “effect”—has been measured. Two kinds of correlation have been tried, namely: (1) the broad-band turbulence signal (hot wire) with the broad-band acoustic signal (microphone); (2) the narrow-band filtered turbulence signal with the narrow-band filtered acoustic signal. The data have been analyzed via the Proudman form of Lighthill's integral for aerodynamic noise. Either type of correlation yields the relative intensity and spectrum of the noise originating from unit volume of the jet; this leads to the variation of noise power per unit length of the jet and the over-all spectrum. The peak normalized board-band correlation of 1%–2% roughly implies that a turbulence “eddy” centered at the hot wire contributes only 1%–2% of the rms sound pressure at the microphone. The total effective number of uncorrelated noise-producing “eddies” is thus of order (1/0.02)2, or some 2500 on an equal strength basis. [Work supported by Air Force Office of Scientific Research.]
Experimental Investigation of the Noise Field of a Supersonic Mach 1.5 Cold Model Jet
Authors: Yu J. C. , Dosanjh D. S.
Published: October 2005

Extensive surveys of both the near and far noise fields were made for a supersonic (nozzle design Mach number 1.5) cold model jet. The operating conditions selected for this investigation were (1) shock-free mode at operating pressure ratio (reservoir pressure/ambient pressure), ξ=3.57 and (2) underexpanded mode at ξ=4.74. The experiments were conducted in a fully anechoic chamber. The purpose of this investigation was to extend the existing understanding of the noise field of a supersonic shock-free jet at a moderate exit Mach number and the variations in its acoustic behavior when the nozzle was operated at underexpanded mode where strong shock waves were present. The main experimental results obtained are presented. It was found that the broad-band and sound-pressure spectra of apparent sources in each of the individual characteristic flow regions were similar. The strongest source for the shock-free jet was located near the laminar core tip, whereas for underexpanded jet, the strongest source was found near the middle of the flow region containing shock waves. It is shown that the significant increase in the noise output at the underexpanded mode of operation was primarily contributed by high-frequency components.
A Review of Low-Frequency Sound Attenuation in the Oceans
Authors: Thorp W. H. , Browning D. G. , Jones E. N. , Mellen R. H.
Published: October 2005

The trend to lower sonar frequencies following WWII has revealed the existence of two and possibly more regimes of excess attenuation of sound in the oceans. The first of these, identified as a relaxation absorption caused by the MgSO4 content in seawater and below. 100 kHz, results in an increase in the absorption coefficient over fresh water by roughly a factor of 20. The second shows a further increase by a factor of 10 below 1 kHz. A number of hypotheses, including a second relaxation, have been proposed to explain the excess attenuation anomaly. Experimental techniques, data analysis, and mathematical models are discussed.
Low-Frequency Sound Attenuation in Open Water
Authors: Duykers L. R. B.
Published: October 2005

A relaxation process, based on organic particulate matter (plankton) in open waters, is described and theoretically derived. It is similar to a theoretically derived and experimentally verified process in aerosols and relates relaxation time to shear (Stokes) force. The derived formulas are applied to demonstrate probable significant differences among low-frequency sound attenuation values in various water masses.
Low-Frequency Sound Attenuation Anomaly in the Ocean: Recent Experimental Measurements
Authors: Browning D. G. , Jones E. N. , Mellen R. H. , Thorp W. H.
Published: October 2005

Numerous explanations have been put forth for low-frequency sound attenuation anomaly in the oceans. Since laboratory measurements are difficult to perform in the frequency range, a series of experiments were conducted in natural bodies of water to determine the effect of salinity, temperature, pressure, and biological activity. The areas in which experiments have been conducted to date are Lake Superior, Lake Tanganyika, Red Sea, and Hudson Bay. The results of these experiments are compared with other recent measurements in the Pacific Ocean and Mediterranean Sea. Although significant variations are noted among the sites, no one mechanism appears to be clearly responsible.
A Critique of Absorption Measurements in the Ocean
Authors: Goodman R. R. , Berman Alan
Published: October 2005

The value of acoustic absorption in seawater in the frequency range substantially below a 1 kHz is sufficiently small that for ranges of about 500 miles the total absorption loss is less than 5 dB. Thus, the absorption loss is very small compared to other transmission losses normally totaling about 100 dB. In order to determine the accuracy of the values for absorption that have been reported in the literature, the authors reviewed the effects which could lead to anomalous values. These results will be discussed.
Possible Chemical Explanation for Low-Frequency Absorption in the Sea
Authors: Atkinson Gordon , Corsaro Robert D.
Published: October 2005

Compilation of low-frequency sound absorption data in the ocean seems to show excess absorption at frequencies below 10 kHz. Here, by excess, we mean absorption in excess of that expected from the high-frequency relaxation spectrum due to MgSO4 ion association. The excess can be fitted to a single relaxation with a relaxation frequency of 1.25 kHz. We have postulated that the above phenomenon is real and due to another chemical equilibrium or set of equilibriums. Using computer techniques that view the ocean as a set of coupled chemical equilibriums, we have calculated the equilibrium concentrations of all the major species. We have then examined the important equilibriums that could give rise to such a low-frequency relaxation. Using chemical knowledge about the kinetic and thermodynamic parameters of these equilibriums, estimates of expected relaxation frequencies and amplitudes can be made. The only equilibriums that could give rise to the anomalous relaxation seem to be those that involve association between the Mg+2 ion and HCO−3, CO2−2, and OH−. Unfortunately, the rate constants for these equilibriums are not known, so a priori calculations of the total sound absorption spectrum of the ocean cannot be made at this time. However, the parameters needed to fit the “observed” relaxation are quite consistent with what we do know about the chemistry of these species. The data and calculations needed to complete the analysis are described. [This research is supported by the Ocean Science and Technology Group of the Office of Naval Research under contract.]
Mechanisms for Anomalous Low-Frequency Absorption of Sound in Seawater
Authors: Yeager Ernest , Fisher Fred
Published: October 2005

Various processes of a chemical nature contributing to the anomalous absorption of seawater are reviewed. The contributions of most of these processes to the absorption coefficient can be predicted quantitatively on the basis of various physical-chemical data obtained from both acoustical and other relaxation measurements. The ionization of water itself to yield hydrogen and hydroxyl ions has a predicted relaxation frequency of 4.5 kHz and should increase the absorption of pure water by approximately 50% at frequencies low compared to the relaxation frequency. This contribution to the absorption, however, is small compared to that caused by such processes as the multiple-step association-dissociation of ionic solutes, particularly, magnesium sulphate and the bicarbonates. [Based on research partially supported by the Office of Naval Research and the National Science Foundation.]
A Theory for Finite-Amplitude Progressive Waves with Directivity
Authors: Lockwood J. C. , Blackstock D. T.
Published: October 2005

Crighton (personal communication) has used a multiple-time scales expansion to solve the problem of a plane periodic finite-amplitude wave. We have adapted this method, applying a multiple-length scales expansion to the three-dimensional nonlinear wave equation derived by Westervelt [J. Acoust. Soc. Amer. 25, 535 (1963)]. When the secular terms in the second-order equation are set equal to zero, a simplified nonlinear equation is obtained. For the plane-wave case, this equation leads to a solution essentially like that of Earnshaw [Trans. Roy. Soc. (London) 150, 133–148 (1860)]. The method is used to obtain an “Earnshaw-like” solution of the problems in which the linear farfield solution is a spherical wave whose amplitude contains a directivity factor D(θ). In particular, the method works for the farfield radiation from a piston, and the “Fubini-like” solution for this problem is presented. Other applications are the radiating disk, the dipole, and arrays. The method is also applicable when the farfield wave is cylindrical. [This work was sponsored by the U. S. Air Force Office of Scientific Research.]
Finite-Amplitude Traveling Waves in N-dimensional Gas Flow
Authors: Schindler G. M.
Published: October 2005

Solutions of the nonlinear fluid-dynamics equations are derived which represent N-dimensional traveling waves of an inviscid gas. At a boundary, which constitutes an (N − 1)-dimensional hypersurface of arbitrary shape moving in N-dimensional space, the flow variables can be described in an arbitrary manner as functions of time and local position. Application is made to N-dimensional radial flow for which the solutions are discussed in view of wave distortion and onset of shocks. The method for deriving these general solutions can be used as well for viscous heat-conducting fluids (Burgers' equation).
On the Mechanism of Finite-Amplitude Entropic Waves
Authors: Peter Abraham C.
Published: October 2005

Initial results of an investigation of finite-amplitude entropic waves are presented. The study is based upon the thermodynamic J-function methods as applied to adiabatic pressure waves with friction. It is shown that a strong coupling exists between the energy of the propagated acoustic wave and that of fluid particle motion. This coupling mechanism causes the energy of the frictional finite-amplitude pressure wave to be dissipated in the convected motion of entropic perturbations. The convection characteristics of these entropic perturbations depend directly upon the frictional flow effects and indirectly upon the thermodynamic-state variables. In particular, when the adiabatic exponent has the value 1.4, the convection velocities of these perturbations are shown to be 0.750 U for small Mach numbers, decreasing to 0.599 U at Mach 2.5, where U represents the fluid velocity. It is also shown that the governing characteristic equations for the thermodynamic states of fluid particles have the following properties: along the finite-amplitude pressure wave, the entropy function depends on pressure only, whereas along the convected entropic “wave” the entropy function depends upon two thermodynamic state variables—and this expression reduces to the isentropic acoustic-wave formula in the last stages of fluid motion as the flow Mach number tends to zero, i.e., as the frictional effects become negligible. [This study has been supported by the Unsteady Aerodynamic Branch of NASA-MSFC, Huntsville, Alabama.]
Computerized Study of Finite-Amplitude Standing Waves in a Duct
Authors: Coppens Alan B. , Ruff Paul G.
Published: October 2005

A one-dimensional model of a finite-amplitude standing wave confined to a duct (wherein boundary-layer effects at the walls produce energy losses greater than those arising from viscous and thermal effects in the body of the fluid) has been established. The resultant set of coupled nonlinear equations can be solved either by a perturbation technique or by assuming a Fourier superposition of standing waves. The perturbation solution has been performed through sixth order and reveals the poor convergence properties of this approach. The Fourier superposition results in an infinite set of coupled nonlinear algebraic equations which can be solved by successive approximations with the help of a digital computer. Results have been obtained for Mb/δ1 below 0.75 and −1.0⩽2Δω/ωrδ1⩽2.0, where M is a Mach number, b = (γ+1)/2, γ is the ratio of specific heats of the gas, α1 = δ1ω/2c0, α1 is the absorption coefficient for the fundamental component of the standing wave in the infinitesimal amplitude limit, ω is the angular frequency of the fundamental, Δω is the difference ω − ωr (where ωr is the classically predicted resonance frequency), and c0 is the speed of sound in the limit b = δ1 = 0. Results show clearly that, for given Mach number, the strongest nonlinear distortions in wave-form are to be observed at frequencies above the classical resonance.
The Acoustics of Narrow Ducts from the Viewpoint of Matched Asymptotic Expansions
Authors: Lesser Martin B. , Lewis Joan A.
Published: October 2005

The classic approach to the problem of determining the acoustic response of a duct narrow compared to the wavelength of the applied disturbance is to assume that the velocity component parallel to the duct axis predominates and to account for the duct cross-sectional area variation through the equation of continuity. These assumptions lead to the “Webster equation,” which together with the concepts of source and termination impedance provides a useful description of acoustic transmission lines. We shall show how these concepts can be clarified and extended by connecting them with the systematic procedure of determining a uniformly valid asymptotic solution to the complete boundary-value problem for the wave equation in a space containing a narrow duct; the duct width to wave-length ratio provides a small parameter which approaches zero. The Webster equation is derived as the first of a sequence of equations for the asymptotic series solution of the problem.
Ultrasonic Propagation in Oriented Nematic Liquid Crystals
Authors: Kemp K. A. , Letcher S. V.
Published: October 2005

Ultrasonic velocity and absorption in bulk samples of p-azoxyanisole and p-azoxyphenetole have been measured at frequencies from 3 to 15 MHz. The liquid crystals were uniformly oriented by means of a magnetic field. Results indicate a definite anisotropy in the absorption for both materials. No velocity anisotropy has been detected. The absorption is greatest when the sound wave is propagated parallel to the field, in the direction of the long molecular axes. Such behavior is consistent with the results reported recently in n- (p-methoxybenzylidene)-p-n-butylaniline [A. E. Lord, Jr., and M. M. Labes, Phys. Rev. Lett. 25, 570 0970)].
Ultrasonic Absorption in Liquid Metals
Authors: Ring E. M. , Beyer R. T.
Published: October 2005

Evidences of structural relaxation effects in the liquid metal alloy system Hg-Tl have been reported in the literature [Abowitz and Gordon, Acta Met. 10, 671 (1962)], referred to in numerous review articles, and reinvestigated in this study, motivated by negative findings in the system Sn-Bi. Pulse-echo measurements between 15 and 325 MHz in the temperature range from 2° to 106°C reveal that no relaxational absorption exists in the system in these domains. The present results are compatible with the previous results if the correction for diffraction effects is omitted. Finally, an anomalous absorption has been found in this temperature range for which a minimum in α/f2 exists at 60°C, but has a classical frequency dependence. The results of other measurements in several liquid metal and semi-metal systems are also presented. [This work was supported by the U. S. Office of Naval Research.]
Ultrasonic Absorption in Nitrate Hydrate Melts
Authors: Hall C. , Smedley S. , Yeager E. B.
Published: October 2005

Ultrasonic absorption measurements have been performed using send-receive apparatus in the temperature range 25°–80°C on the system calcium nitrate hydrate+cadmium nitrate hydrate. The apparent relaxation reported by other workers at about 18 MHz in the pure calcium nitrate hydrate is shifted to a lower frequency and the relaxation strength is increased by the addition of the cadmium salt. When steps are taken to remove bubbles in the melts, however, the ultrasonic absorption data no longer give any indication of such relaxation effects. [This research is supported by the Office of Naval Research.]
Nonlinear Acoustical Parameters of Piezoelectric Crystals
Authors: Ljamov V. E.
Published: October 2005

The wave equation for elastic waves in piezoelectric crystals is found, including the third-order terms in the expansion of the thermodynamic potential in the strain and electric field. The effective nonlinear acoustical parameters for a general crystal are obtained. In the general case these parameters depend on the second-order and third-order coefficients: nonlinear piezoelectric, electrostrictive, and linear electrooptic. These coefficients are considered for piezoelectric and nonpiezoelectric crystals. The properties of the nonlinear piezoelectric tensor are discussed giving some estimate of the value of the nonlinear coefficients. The dependence of sound velocity on the external fields (strain and electric field) and wave interaction is discussed. [Research carried out while visiting at the University of California, Berkeley 94720.]
Flexure Mode Piezoelectric Transducers
Authors: Germano C. P.
Published: October 2005

Although flexurally responsive piezoelectric elements have been utilized for a few decades, interest in their utility remains high. This is a result of the ability of such structures to generate high output from sources of low mechanical impedance, or, conversely, to develop large displacement at low levels of electrical excitation. Typically a bending response is obtained from a sandwichlike structure of two properly oriented piezoelectric expander plates in which case the unit is referred to as a bender Bimorph. However, other approaches to benders include the Unimorph, the Multimorph, and other specially treated single plate elements. Numerous applications utilizing bender elements exist. To aid in meeting the variety of requirements presented by these applications, the supplier has available to him many options. These variables include choice of materials, geometry, and electrode configurations. In terms of volume of usage, the phonograph cartridge remains the number one application. However, many other electroacoustical devices are made possible by the availability of the Bimorph or its modified alternates Some of these are indicated. In addition, the utility of the equivalent circuit and its constants are described.
Use of Solid-State Acoustic Transducers in Communications
Authors: Mason Warren P.
Published: October 2005

Semiconductor and solid-state devices have been used extensively to measure and generate stresses and stress waves in solids, liquids, and gases. Semiconductor devices have been used as strain gauges to measure strains and to respond to acoustic pressures. p-type silicon has a guage factor of over 100 times that of a metallic strain gauge. By using the amplifying regimes of Esaki diodes and transistors, a great increase in sensitivity is obtained and microphones have been constructed that are more sensitive than the carbon microphone. With the advent of monolithic transistor on single chips and films, it appears likely that the most stable and economical devices are obtained by separating the pickup and amplifying functions. p-n junctions have a region (the depletion region) where electrons are excluded and if the semiconductor is piezoelectric, very high-frequency transducers for generating mechanical waves in solids can be produced. Evaporation techniques can also be used to produce frequencies from lower ranges to very high-frequency ranges. With the advent of more highly coupled piezoelectric crystals and ceramics, this technique may be extended further. Solid-state transducers have also been constructed using the Hall effect and the magnetoresistance effect. These have been applied in measuring static and dynamic fluxes, as variable resistors without sliding contacts and as displacement meters and microphones.
Electrostatic Transducers for Bioacoustical Instrumentation
Authors: Palin J. , Fay R. R. , Simmons J. A.
Published: October 2005

Previously described electrostatic transducers [Beavers, Palin, and Simmons, J. Acoust. Soc. Amer. 48, 126–127 (1970)] have been used as sound sources in closed earphone systems. A 34-in. or 12-in. transducer earphone driving a short closed tube is capable of delivering up to 100 dyn/cm2 to an animal at frequencies from 100 Hz to 20 kHz. Second-harmonic distortion is better than 30–35 dB below the fundamental, and higher-order harmonics fall below this level. As sound sources, these transducers are very inexpensive and superior in performance to commercially available condenser microphones commonly driven as loudspeakers. They are excellent sources for click and tone-burst stimuli in neurophysiological research owing to their good transient response. With a simple driver amplifier incorporating a low-cost high-voltage transistor, such devices can serve for all types of bioacoustical research at audible and ultrasonic frequencies. They have been used for auditory research as loudspeakers and as microphones at frequencies from below 100 Hz to over 175 kHz.
Two-Dimensional Notations for the Specification of Sound and Music Synthesis
Authors: Henke W. L.
Published: October 2005

An interactive (online) computer aided system (entitled MITSYN) for sound and music synthesis and composition is being developed. The usability of such systems is dependent upon the perspicuousness and palatability of the notations and the “syntax” of the user-machine interaction. MITSYN'S notations are mostly two dimensional or graphical in nature, a form to which most humans are much more attuned than character string oriented notations. Signal processing “configurations” are specified with a graphical “configuration editor” using a block diagram representation. Temporal control is provided by “parameter files” (“scores”), edited with a “parameter editor,” in which the horizontal dimension is time and the vertical dimension specifies other attributes of either temporally continuous parameter tracks or discrete “event” notations. A “waveform editor,” an “audio editor,” and a synthesizer are other major segments of the system. The implementation of MITSYN is an example of a fairly sophisticated level of interactive computer graphics and sonics being quickly realized on a quite modest computer system (PDP-9 CPU) with the aid of a programming language and system designed for such types of applications. [Supported by the U. S. Air Force.]
Improved Equipment for Plotting Resonance Curves for Wind Instruments
Authors: Backus John
Published: October 2005

Previously published resonance curves for the clarinet [J. Acoust. Soc. Amer. 43, 1272–1281 (1968)] were made by exciting the air column of the instrument by means of an external sound source. This method turned out to be unsuitable for the bassoon; the shape of the resonance curve depended greatly on where the external sound source was located. Used with the brass instruments, the method gave resonance curves with spurious peaks at high frequencies. A better method is to conduct sound from the driver unit directly to the sealed off mouthpiece through a high acoustical resistance and measure the resulting pressure amplitude in the mouthpiece as a function of frequency. Hence an acoustical resistance was constructed which is frequency independent over the desired range and whose impedance is high compared with that of the instrument to be measured. This resistance is attached to the driver unit along with a monitoring microphone to keep the input constant. Adapters have been constructed which allow the driver and resistance combination to be coupled to various wind and brass instruments. Resonance curves for the various instruments will be shown. [This work was supported by the National Science Foundation.]
Violin Resonances Studied by Electrical Simulation
Authors: Mathews M. V.
Published: October 2005

A study of the resonances of a violin was made by attaching an electric pickup to the strings of a normal violin and passing the signal so obtained through a set of electrical resonances. Frequencies, bandwidths, and amplitudes of the resonances could easily be adjusted and resulting sound evaluated aurally. About 20 resonances were used. The frequencies were set equal to the peaks of a published response curve of a Stradivarius. Amplitudes could be adjusted so the tone matched a range of instruments from an orchestral violin to a hillbilly fiddle. Bandwidths from 7 to 100 Hz were tried, about 50 Hz being best. Components of the sound due to individual resonances were heard separately. Low-frequency resonances gave a rich but muffled tone, midfrequency resonances a thin sound, and the high-frequency resonances a harsh penetrating sound.
Vibrations in Unassembled Violin Plates Compared by an Acoustical Method and Hologram Interferometry
Authors: Hutchins Carleen M. , Stetson K. A. , Taylor P. A.
Published: October 2005

Hologram interferometry is making possible the visualization of transverse waves in the wooden bodies of stringed instruments under vibration. The present study is an attempt to coordinate the information now being obtained from holograms of unassembled violin plates with criteria previously developed in the course of the successful construction of 100 instruments in which the sound radiated from the plates is measured as a function of frequency. Comparisons will be made between holograms and acoustical tests of flat plates versus arched plates, and plates made intentionally “correct” versus “incorrect” according to violin making practice.
Variations in Tonal Characteristics and Construction of the Viola
Authors: Hutchins Carleen M. , Saunders Frederick A.
Published: October 2005

The viola as it exists for classical music is a compromise instrument, made to play comfortably under the chin using frequencies a musical fifth below those of the violin. Simple proportionality suggests that an instrument producing wavelengths of sound half again as long as another should be 1.5 the size. Increasing the 14-in. length of the conventional violin body to 21-in. in the viola would yield an instrument much larger and less manageable than the conventional viola, whose size ranges from 15 to 17.5 in. Over 60 violas have been constructed which incorporate more or less drastic experimental features in an effort to minimize playing difficulties and optimize tonal characteristics, based on structural features that are measurable and to a large degree predictable. Different violas will be demonstrated and their acoustical features discussed, including a 12-in. child size, three average 16-in. instruments, two 20-in. violas, and two expendable experiments.
Mode Patterns Microphonically Observed
Authors: Schelleng John C.
Published: October 2005

The beauty of the hologram method for studying modal patterns should not obscure the fact that in the case of violin plates a simpler method may sometimes be adequate. Diagrams made in 1968 showing contour lines of vibrational amplitude—most of them nodal lines—will be shown for a violin top and two backs. The plate is supported by rubber pillars at nodes and electronically excited at an antinode, all apparatus being inexpensive. Pickup was acoustical, the opening into the microphone being a small hole at the apex of a cone, which is moved over the surface at a distance of 1 or 2 mm (the distance is not critical.) The method is reliable for plates, but cannot be used for assembled instruments, in which sound pressure no longer depends primarly on the vibration of the adjacent surface.
Dynamic Bending in the Top and Back Plates of the Violin
Authors: Lee R. M.
Published: October 2005

While a violin was bowed to produce steady-state tones, vibration waveforms at selected points on the top and back plates were detected with an optical sensor. The data thus obtained was entered into a computer which was programmed to produce both static and dynamic displays of the data. Measurements were made on both the top and back plates of two violins for each of the four open strings. The displays show the highly assymetrical operation of the instruments, the differences between the bending of the top plates and the bending of the back plates, and the effect of frequency on the bending patterns. The equipment and techniques developed are applicable to studies of a wide range of vibrating surfaces.