bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotation rate sensing with acoustic surface waves
Authors: Frost H. M. , Sethares J. C. , Szabo T. L.
Published: October 2005

Previous workers proposed using contactless transduction of acoustic surface waves (SAW's) for rotation rate sensing [R. G. Newburgh, P. Blacksmith, A. J. Budreau, and J. C. Sethares, Proc. IEEE 62, 1621–1628 (1974)]. We describe here a device that employs (as proposed) electromagnetic SAW transducers (EMT's) and readily measures rotation rates from 1 rpm to 2 rev/day. Curved, 1-MHz transmitter (pulsed) and receiver EMT's are conformally mounted on diametrically opposite sites of an aluminum cylinder rotating within a static magnetic field. Receiver pickup of circulating clockwise and counterclockwise SAW's on the cylinder circumference yields complex standing-wave signals whose amplitudes vary with frequency F = CF′ with F′ the rotation rate in rev/sec (F is in Hz). Values of the constant C determined both by a theory for a standing-wave pattern fixed on the cylinder surface and by experiment agree to within 1%. Feasible design improvements include sensitivities of 0.02°/h and use of permanent magnets to avoid cylinder rotation braking by magnetic torques. [Work supported by National Research Council, AFCRL, and AFML.]
Contemporary noise control programs in Australia, Brasil, and Japan—An assessment
Authors: Jhaveri Arun G.
Published: October 2005

Since the beginning of this decade, a large number of developing as well as industrialized countries of the world have committed a small fraction of their national resources to combat the detrimental impacts of environmental pollution. The control and abatement of environmental and occupational noise levels in many urban communities has been a difficult and sometimes frustrating exercise as it involves planning, development, and implementation of realistic as well as enforceable legislations, regulations, or ordinances. Nonetheless, it is encouraging to note that both the less developed and highly developed (industrialized) nations have made definite contribution towards reduction of the unnecessary, excessive, harmful, and annoying noises. The object of this paper is to review, evaluate, and summarize the current plans and programs to control environmental noise pollution in Australia, Brasil, and Japan. The author has witnessed first hand the strategies used for noise abatement in Brasil and Japan, while he has had detailed discussion with an official responsible for managing noise control programs in Australia. There appears to be a close resemblance in the noise control methodologies utilized in the United States and those in the three countries under consideration. The author believes strongly in developing mutually acceptable programs of scientific, technological, and educational exchange as well as assistance amongst these countries in order to systematically and efficiently control the growing, serious national noise menace.
Use of an overhead projector to demonstrate wave-motion phenomena
Authors: Koehl G. M.
Published: October 2005

Standing waves, wave propagation, reflection, and refraction can be demonstrated by using simple, easily constructed apparatus on an overhead projector.
Multipurpose tester for phenomena in vibration and impact
Authors: Seireg A.
Published: October 2005

The film describes a multipurpose dynamic tester capable of demonstrating several phenomena of vibrations and impact. The versatility of the equipment makes it suitable for a wide range of educational levels from elementary demonstrations in vibrations to investigations on the graduate level. Due to its capabilities of producing both the simple and complicated dynamic situations, it would stimulate interest in the students to explore the complicated situations after thoroughly understanding the simple ones. The equipment can be also utilized in testing the effectiveness and in calibration of new instruments or circuits designed by the students for measuring dynamic phenomena. It also provides a versatile model for research problems in vibrations on the undergraduate as well as the graduate level. The tester is a two-mass system with controllable linear and nonlinear elastic and damping characteristics. The system excitations are provided by two variable-speed exciters on the main and secondary masses, respectively, a frictional wheel drive on the main mass for inducing self-excited vibrations, and ballistic pendulums capable of providing different impulses on both masses. [The tester was developed at Marquette University in 1962 under a Science Teaching Equipment grant from the National Science Foundation.]
Diffraction of light by ultrasonic waves
Authors: Breazcale M. A.
Published: October 2005

The laser makes possible a very simple optical system-no lenses!-for demonstrating light diffraction by ultrasonic waves in water. We will demonstrate zeros of intensity in diffraction orders resulting from the fact that In = K Jn2(ν) for progressive ultrasonic waves; diffraction by standing waves, by crossed waves; and the effect of nonlinear distortion of the ultrasonic waves. An attempt will be made to demonstrate the effect of parametric oscillation in a standing ultrasonic wave system. [Research supported in part by the Office of Naval Research.]
Vibrotactile frequency for encoding speech parameters
Authors: Rothenberg M. , Verrillo R. T.
Published: October 2005

Frequency of vibration has not been widely used as a parameter for encoding speech-derived information on the skin. Where it has been used, the frequencies employed have not necessarily been compatible with the capabilities of the tactile channel, and no determination was made of the information transmitted by the frequency variable, as differentiated from other parameters used simultaneously, such as duration, amplitude and location. However, several investigators have shown that difference limens for vibration frequency may be small enough to make stimulus frequency useful in encoding a speech-derived parameter such as the fundamental frequency. In the studies reported here, measurements have been made of the frequency discrimination ability of the finger, thenar eminence, and forearm, using both sinusoidal and pulsed waveforms. Stimulus configurations included the constant frequency vibrations used in previous experiments as well as frequency-modulated (warbled) stimulus patterns. The frequency of a warbled stimulus was designed to have a temporal variation analogous to those found in speech. The results suggest that the fundamental frequency can be displayed on the skin as a vibratory frequency if recoded into a frequency range closely matched to the skin's capability.
Dichotic listening and orientation of the writing hand in left-handers
Authors: Thistle Anne B.
Published: October 2005

Eighteen left-handed, paid volunteers participated in a dichotic listening study designed to test the hypothesis of Levy and Nagylaki [Genetics 72, 117–128 (1972)] that orientation of the hand in writing (upright or inverted) should be correlated with direction of dichotic ear advantage. Fisher's Exact Test revealed no such correlation in this group of subjects for either of two different criteria of hand orientation.
Acoustic determinants of “stimulus dominance” in dichotic competition
Authors: Repp Bruno H.
Published: October 2005

When synthetic stop-consonant-plus-vowel syllables are presented dichotically, one of the two competing stimuli usually “dominates” the other, i.e., it is more often correctly identified (in a single-response paradigm). The degree of the “stimulus dominance” depends, at least in part, on the acoustic characteristics of the stimuli. By varying voice onset times and/or formant transitions within phonetic categories, stimulus dominance relationships can be reliably influenced and occasionally even reversed. Similarly, the frequency of “psychoacoustic fusions” (/d/ responses to /b-g/ pairs) and of “blend” errors (e.g., /d/ responses to /b-t/ pairs) depends on these acoustic factors. These results suggest strongly that dichotic interaction takes place before categorization of the stimuli or of their features. However, the data also suggest that a fairly abstract auditory level is involved and not a simple mixing or averaging of information. Deliberate systematic variation of stimulus dominance relationships holds some methodological promise: by treating this factor as “bias,” the dichotic ear advantage may be measured more accurately as “sensitivity,” using methods derived from signal detection theory.
Auditory processing factors in dichotic CV tasks
Authors: Dermody Phillip , Noffsinger P. Douglas
Published: October 2005

The use of dichotic measures has been principally directed, especially in pathological populations, to the investigation of ear effects. It is also possible to use dichotic tasks as measures of auditory processing by considering such aspects of performance as the total correct score and the number of double-correct responses. The auditory processing abilities of three groups of subjects were investigated in this context. CV stimuli were presented under simultaneous and 90-msec lag conditions to 10 adults with multiple sclerosis, 16 persons with presbycusis, and 15 children with learning disabilities. The results were compared to those of 15 normal controls as well as to the normative data reported in the literature. Overall, the dichotic measures did differentiate the pathological populations from normals. Furthermore, performance in terms of the double-correct responses shows differences in the auditory processing abilities between each of the pathological populations. It is concluded that the investigation of double-correct responses as an index of auditory processing capacity should be a valuable addition to the use of dichotic measures in pathological populations, with interesting implications for the mechanisms involved in the disruption of dichotic listening abilities.
Vowel normalization by linear transformation of each speaker's acoustic space
Authors: Harshman Richard A. , Papcun George
Published: October 2005

Different speakers uttering phonetically equivalent vowels will not, in general, produce the same set of formant frequencies. Some of these variations are due to global differences in the shape of the acoustic space from one speaker to the next. We have investigated a family of linear transformation techniques for removing these global variations while preserving intervowel relationships. Patterns of interspeaker variation are first determined by PARAFAC three-way factor analysis of the formant × vowel × speaker data set. The resulting factors suggest dimensions of consistent interspeaker variation which may eventually be identified with physiological or psychological factors affecting vowel production. For the purpose of normalization, each speaker's space is stretched in the directions of the (usually oblique) factor axes, in amounts inversely related to the person-weights on the factors. This produces a restricted “least squares” optimal removal of individual differences due to these linear common factors of speaker variation. The effects of this normalization procedure will be demonstrated with data from several languages and compared with the results of Gerstman's range equalizing technique and Wakita's tract length normalizing technique. [Work supported by NSF.]
Study of intrinsic pitch of vowels
Authors: Delos M. , Guerin B. , Mrayati M. , Carre R.
Published: October 2005

It is established that high vowels have a higher intrinsic pitch than low vowels. But we found that nasalization of these vowels reduces this difference which vanishes in the case of French nasal vowels. These phenomena can be due to the combination of the following three types of source-tract coupling: (a) For very closed vowels, the vocal-tract constriction introduces an air-flow resistance which tends to raise the intraoral pressure and thus reducing the pressure difference across the glottis. This effect alone could account for a slight decrease in voice fundamental frequency. (b) The input impedance of the supraglottal cavities represents the voice-source acoustic load. We studied this type of coupling in simulating a nonlinear two-mass vocal-cord model loaded by an equivalent circuit of the vocal tract driving point impedance. It is found that the fundamental frequency decreases when the first formant frequency or bandwidth is lowered. (c) It is known that a mechanical interdependance exists between the supraglottal configuration and larynx position. Larynx movements change the vocal cord mechanical characteristics and consequently the oscillation frequency. From our results, it seems that the third type of coupling is predominant and could explain the intrinsic pitch of vowels.
Further studies on vowel length before aspirated stops
Authors: Maddieson Ian
Published: October 2005

A paper presented at the 90th meeting of the Acoustical Society [I. Maddieson and J. Gandour, J. Acoust. Soc. Am. 58, S61(A) (1975)] demonstrated that vowels before word-final aspirated stops in Hindi are longer than before the unaspirated counterparts. The present paper expands the scope of the earlier report, both in the range of languages and the variety of environments examined. The duration of vowels before final and intervocalic stops in Eastern Armenian, Bengali, and Gujarati, and before intervocalic stops in Hindi was measured. The results show that the tendency for longer vowels to occur before aspirates is consistent, although the degree of lengthening is variable.
Biological sound scattering in the oceans: A review
Authors: Farquhar G. Brooke
Published: October 2005

An Office of Naval Research-sponsored conference was held in November 1975 to determine approaches to predicting volume reverberations based upon physicochemical, biological, acoustic, and modeling considerations. Review papers were presented in plenary session for each disciplinary area, after which working groups were convened to assess current understanding, review problems, and prepare recommendations. This paper is the substance of the review given in plenary session on biacoustic aspects of sound scattering. Biological backscattering is frequency dependent, and varies with depth, time of day, season, and area. Both resonant and nonresonant scattering effects are involved. Gas-filled swimbladders of mesopelagic fishes dominate resonant effects, especially at frequencies below about 30 kHz, although these fishes and many others may contribute as well to nonresonant, geometric scattering, depending upon acoustic wavelength. At higher frequencies (40–300 kHz), various zooplankton groups are discernible using single-frequency sources. Column scattering-strength spectra over the range from about 1–20 kHz show definite patterns and variations which are relatable to oceanographically and biologically defined regions in the oceans.
Effect of light and angle of incidence on acoustic observation of biologically enhanced layers in the ocean
Authors: Fisher F. H. , Squier E. D.
Published: October 2005

Target strengths of scatterers as a function of depth have been measured from FLIP [F. H. Fisher and E. D. Squier, J. Acoust. Soc. Am., 58, S102(A) (1975)] with our narrow-beam (1°) 87.5-kHz echo-sounder at angles of 0° and 30° from normal incidence. The results from depths ∼150–300 m are the same at both angles, indicating that point scattering is involved. Turning on a 500-W light produced a rapid response in some of the scatterers. Turning off the light did not produce a similar effect. Use of short pulses (7 cycles) revealed structure within the deep scattering layer (DSL) as it migrated downward. [This work was supported by the ONR.]
Acoustic estimates of fish density and scattering function
Authors: Peterson Miles L. , Clay C. S. , Brandt S. B.
Published: October 2005

The signal processing techniques for acoustically estimating fish abundance are echo counting and echo integration. The transducer beam pattern complicates these estimates. We (1) statistically model the effects of the beam pattern on scattered signals, (2) compare acoustic data to this model, and then (3) for echo from individual fish, calculate estimates of fish density and scattering function based on these comparisons. At low densities we determine the proportionality constant relating the average echo integral and fish densities. Then at high densities, this proportionality is used to estimate fish density. The theory is compared to experimental data for alewife in Lake Michigan, U.S.A.
Temperature rise in tissue: Continuous and pulsed ultrasound regimes
Authors: Fry F. J. , Erdmann W.
Published: October 2005

Temperature rise in mouse testicular tissue is a linear function of incident cw ultrasound intensity (0–130 W/cm2). Small-diameter chromel-constantan thermocouples are used to measure the temperature rise. The absorption coefficient for this tissue (0.029 to 0.070 cm−1 intensity absorption coefficient at 1.1 MHz) provides temperature rises not exceeding 4–5°C with our focused ultrasonic irradiators. When pulse regimes are employed, the linear relationship between temperature rise and average intensity applies in limited circumstances. With spatial peak intensity less than 100 W/cm2 and burst time 100 msec or longer (1000 Hz prf) the temperature rise seems linearly related to average ultrasound intensity. For peak intensities above 100 W/cm2, average intensities below 10 W/cm2, and burst times below 100 msec, the temperature rise is essentially linearly related to peak intensity. For peak intensities below 100 W/cm2 and average intensities below 2–3 W/cm2 the temperature rise appears to be that characteristic of the continuous wave case. Preliminary data on mouse ovarian tissue indicate the same general phenomena is operative. Various experimental configurations have been uses in an attempt to demonstrate that the observed phenomena is a tissue ultrasound interaction effect and not an artifact of the tissue-thermocouple complex.
In vitro thermoacoustic studies in brain
Authors: Sachs Thomas D. , Anderson Peter T. , Wright Sanford J. , Grimes Ralph S. , Janney Clinton D.
Published: October 2005

The TAST system passes a burst of “thermometer” sound beam through tissue, and measures its transit time. Next, a focused heating sound field warms a small volume of tissue in the path of the thermometer beam, in proportion to its absorption. Finally, the thermometer-beam burst is repeated and its transit time subtracted from that of the initial thermometer-beam burst. This time difference characterizes the tissue because it depends on the absorption coefficient and the temperature coefficient of velocity. Both are apparently sensitive to tissue structure as well as other tissue characteristics. In a fixed human brain TAST distinguished among various intracranial structures with a spatial resolution of better than 3 mm. Should predictions based on the data and theory prove correct, TAST may become a noninvasive alternative to biopsy. [Work supported in part by the Sloan Foundation.]
Acoustic mass flowmeter for automotive exhaust measurements
Authors: Potzick James , Robertson Baldwin
Published: October 2005

A design for an acoustic mass flowmeter for use on automobile exhaust is described. A sound field with wavelength longer than the cutoff wavelength of the meter pipe is used. Three microphones in the wall of the pipe are used to sense the zero crossing times of the sound wave. The frequency of the sound is varied as necessary by means of electronic feedback to keep the wavelength constant as the temperature of the gas changes. The meter discriminates effectively against the high-level noise found in auto exhaust and directly measures true mass flow averaged over the cross section of the pipe. Experimental data will be presented if available.
Prediction and propagation of urban traffic noise levels
Authors: Bradley J. S.
Published: October 2005

The problem of predicting urban traffic noise levels was divided into two parts: the prediction of traffic noise levels close to the road and the propagation of the traffic noise through an urban environment. Field data has been gathered to study both halves of the problem. Six existing traffic noise prediction schemes have been evaluated with respect to predicting noise levels close to the road. Modified versions of empirical equations were developed to provide improved prediction accuracy and to allow the prediction of Leq. Propagation measurements were made over open sites, down side streets, and through rows of buildings. Simple prediction schemes have been found to approximate the attenuation of Leq values down side streets, and through rows of buildings. Considerable scatter of the attenuation values from the mean trend is found on remeasuring at a site and between superficially similar sites.
Sound power level determination for turbine-generator sets
Authors: Staiano M. A.
Published: October 2005

Presently accepted acoustical-measurement standards are not adequate for sound power level determination of large machines such as turbine-generators in power plants. These standards yield erroneous values of sound power level particularly as a result of measurement environment and background noise effects. Sound pressure levels measured around a number of fossil turbine-generator units were used to investigate the influence of several sources of error. This data showed that a simplified measurement sample would yield adequately small errors. “Upper estimates” of turbine-generator sound power level, calculated using this scheme with environmental corrections based upon ISO/DIS 3746 and without corrections for background noise, resulted in only moderate scatter. This procedure, with the incorporation of a suitable background-noise correction method—possibly via directional microphone, is promising and should be explored in future studies.
Estimation procedure for sound diffraction by nearly rigid wedges
Authors: Hadden W. James , Pierce Allen D.
Published: October 2005

The results of a theoretical investigation of the diffraction of sound barriers are presented for situations in which the barriers may be modeled as wedges whose faces are characterized by large (but not infinite) acoustic impedance. Plane-wave and point source excitation are considered. The estimation procedure makes use of the fact that for certain wedge angles the diffracted sound field can be obtained relatively simply. Curves are presented which facilitate the computation of an insertion loss for the barrier as a function of source and receiver locations and the impedance and interior angle of the wedge.
Variability of loudness comparisons
Authors: Lim J. S. , Rabinowitz W. M. , Braida L. D. , Durlach N. I.
Published: October 2005

The preliminary theory of intensity resolution [N. I. Durlach and L. D. Braida, J. Acoust. Soc. Am. 46, 372–383 (1969)] is extended to encompass the variability that occurs in comparing the loudness of different types of stimuli. The extended theory is identical to the preliminary theory except for the addition of a new variance term (the “transformation variance”) to the trace-mode variance. New experiments on the variability of loudness comparisons for tones of different frequencies are described and interpreted in terms of the theory. The paradigm used in these experiments is identical to the conventional two-interval roving-level intensity-discrimination paradigm [J. E. Berliner and N. I. Durlach, J. Acoust. Soc. Am. 53, 1270–1287 (1973)], except that the stimuli in the two intervals have different frequencies. The results show that the total discrimination variance increases monotonically with the frequency separation between the stimuli and that for f1 = 1000 Hz the variance increases by roughly a factor of 7 as f2 is decreased from 1000 Hz to 650 Hz. [Research supported by NIH.]
Subjective response of occupants to automobile interior noise
Authors: Dickinson S. M.
Published: October 2005

A continuation of a project initiated by Ford Motor Company, England, is described, the objective of which was to arrive at a means of predicting subjective response to interior car noise from objective measurements. Their initial work had involved the development and subsequent proving of a high-quality recording and replay system, allowing subjective testing to be conducted in the laboratory rather than in the field. Subjective tests (paired comparisons) were conducted by both Ford and the author using a tape specially prepared by both Ford and the author using a tape specially prepared from recordings of interior noise from several different vehicles. The results, together with results from further subjective tests involving the use of spectrum-shaped interior noise, showed that conventional indices such as dBA, dB B, and PB dB were not satisfactory for the prediction of subjective response, but indicated that a weighting scale similar to the A-scale but not attenuating the very low frequencies so much and attenuating medium low frequencies more may be satisfactory. Such a curve has also been proposed (and quantified) by H. W. Spring [Interkeller Gap (1975)] and has been found by the author to give complete rank order correlation between his subjective and objective results.
Convergence of transient response computations for cylindrical shells based on the Williams and mode-superposition methods
Authors: Sobel L. H. , Chandra S.
Published: October 2005

This paper investigates the axisymmetric transient response of elastic cylindrical shells that are excited by radial pressures with various spatial and temporal distributions. A comparison is made of the numerical convergence behavior of the displacement and stress/strain responses appropriate to the Williams method and the more widely used mode-superposition method. For the Williams method, an exact solution is obtained herein for the so called “quasi-static” portion of the total response. The remaining portion of the response is represented by a series of normal modes, as is also done for the total response in the usual application of the mode-superposition approach. Consequently, the convergence behavior of the response computations appropriate to the Williams method is at least as good as those based on the mode-superposition method, and it is considerably faster for problems in which the loads are sharp in space. This is particularly true for the higher-order derivative variables, such as flexural stresses and strains, transverse shear forces, and accelerations. Application of the mode superposition method to such problems can be quite costly, as solution of a larger eigenvalue problem is generally required for the generation of the normal modes. The above considerations are illustrated in the paper, which presents numerical results for a number of example problems.
The acoustic monopole in motion
Authors: Norum T. D. , Liu C. H.
Published: October 2005

A widely used experimental version of the acoustic monopole consists of an acoustic drive of restricted opening forced by a discrete frequency oscillator. To investigate the effects of forward motion on this source, it was mounted above an automobile and driven over an asphalt surface at constant speed past a microphone. The received signal was compared to results computed from an analysis of a fluctuating-mass-type point source moving above a finite impedance reflecting plane. Good agreement was found between experiment and theory when a complex normal impedance representative of a fairly hard acoustic surface was used in the analysis. Nonuniform motion of the source was also considered by analyzing the monopole moving with constant acceleration in free space. Computation of the observed signal indicates teat deviations from the constant velocity case become noticeable only at rather large values of acceleration.
Thresholds for apparent auditory motion induced by linearly changing interaural time differences
Authors: Brandauer C. M. , Ward Wayne
Published: October 2005

That listening dichotically to two waveforms differing slightly in frequency produces an image that appears to move from one ear to the other is well known [e.g., Lord Rayleigh (J. W. Strutt), Philos. Mag. Ser. 6 13, 214–232 (1907)]. We have determined the thresholds for apparent auditory movement using low-pass-filtered pulse trains by changing the interaural time difference T by an increment t with each dichotic pulse pair. Two major experimental paradigms were used with several pulse repetition rates and initial values of T. In the first paradigm, t, a measure of movement rate, was the independent variable and N, the number of pulse pairs or movement time required for the movement threshold was determined. The second paradigm reversed the roles of t and N, thus yielding the required movement rate for a given movement time.
Psychophysical tuning curves in normal and pathological ears
Authors: Carney Arlene Earley , Nelson David A.
Published: October 2005

Psychophysical tuning curves were obtained for normal listeners and listeners with sensorineural hearing loss in a simultaneous tone-on-tone masking procedure. As reported by Leshowitz et al. [J. Acoust. Soc. Am. 59, S2(A) (1976)], the tuning curves for several pathological ears showed no finely-tuned portion in the frequency regions where threshold was elevated. Although two subjects demonstrated broad-band, relatively flat sensorineural losses, the pattern of their tuning curves varied markedly with signal frequency. To examine this frequency effect, and to determine the effect of overall sound pressure level on frequency selectivity, tuning curves for normal listeners were run at two levels: (1) with probe at 10 dB SL; (2) with probe at sound pressure levels comparable to those experienced by pathological ears. The implications of these results for frequency selectivity in hearing impaired listeners will be discussed. [Work supported in part by NIH.]
Research in electronic determination of speech intelligibility
Authors: Schiller E.
Published: October 2005

A simple, fast, accurate and inexpensive device for the evaluation of speech intelligibility of communication equipment and systems is the subject of this investigation. The subjective methods presently used for evaluating intelligibility require extensive training and controls over the testing for accurate predictions of intelligibility. but still show variability between testing labs and are not standardized for different languages. Therefore, an instrument for evaluating intelligibility cannot be expected to correlate with all subjective tests, but it can produce the same results as all identical instruments under similar conditions any place on earth. This repeatability would be valuable to the Navy and probably to many other organizations.
Review of the ARPA speech understanding project
Authors: Klatt Dennis H.
Published: October 2005

After five years of research and development, the final three speech understanding systems funded by the Advanced Research Projects Agency of the Department of Defense were demonstrated in early September of this year. As a member of the ARPA Steering Committee and as a consultant for one of the research groups, I will offer a summary of the capabilities that were demonstrated, and also speculate on the scientific knowledge gained during the course of the program. The opinions to be expressed are entirely the author's.
Pedagogical aspects of teaching acoustics to a general student group
Authors: Savage William R.
Published: October 2005

At a number of colleges and universities courses in introductory acoustics and related areas are being offered. Often these courses are taught in the physics or physical science departments as a science subject. This is not a universal rule since similar courses are found in departments such as speech science, architecture, etc. The teacher may have a deep interest in acoustical phenomena without being a professional acoustician. The courses may serve as a required course for students in the speech sciences or music. These courses can have a large enrollment when they are open to general interest students. Many of the teaching methods relate to the task of explaining a phenomenon that is described perhaps best, at least compactly, by mathematical methods with visual or audible teaching aids.
Keller Plan applied to instruction in acoustics
Authors: Chial Michael R.
Published: October 2005

Undergraduate students in audiology, speech pathology, and education of the deaf present two problems for the would-be teacher of acoustics. First, they are typically deficient in basic mathematics and physics. As a result, they fall victim to “symbol shock,” a disorder characterized by glazed eyes and cortical dysfunction. Second, they require at least a modest understanding of acoustics for their later professional health. A reasonable treatment has been found in the form of the Keller Plan or the Personalized System of Instruction (PSI). This plan has been used successfully for four years in an undergraduate course designed to convey the rudiments of physical acoustics, bioacoustics, and psychoacoustics. PSI uses explicit performance criteria, unit mastery, self-pacing, and individualized tutoring. Laboratory demonstrations are used for motivational purposes and to promote student discovery. Critical information is conveyed by the written word; lectures are given only upon student request. Details of the PSI method will be presented, as well as the results of a modest retrospective analysis of the course taught under traditional and PSI formats.
Antennas for sodar systems
Authors: Kurze U. I.
Published: October 2005

The remote probing of the thermal structure and the wind velocity in the lower atmosphere requires highly directive antennas, which should have a half-power beam width of about ± 6° (3-dB points), a 90°-side-lobe suppression of at least 40 dB, little volume reverberation, low wind sensitivity, and be made of weather-proof material. Various off-axis parabolic horn antennas have been built and acoustically evaluated, considering additional requirements of mobility. The performance of shielding tubes and their absorbent lining, the transmission loss of the antenna walls and the influence of antennas of different size have been evaluated both theoretically and experimentally. Detailed studies of antenna elements are supplemented by field applications of sodar systems.
Observation of upper atmosphere warmings with the use of natural infrasound
Authors: Rind D. , Donn W. L.
Published: October 2005

Natural infrasound of 5 sec period is generated by interfering ocean waves in the Atlantic Ocean to the east of our location. Our normal amplitude pattern of infrasound in winter is characterized by semidiurnal and diurnal oscillations associated with reflecting tidal winds in the lower thermosphere [W. L. Donn and D. Rind, J, Atmos, Sci, 29, 156–172 (1972); D. Rind and W. L. Donn, J. Atmos. Sci. 32, 1694–1704 (1975)], Occasionally an amplitude pattern featuring continuously strong signal throughout the day is observed. Eight of these cases were investigated and it is shown, with the use of observations at Wallops Island, that seven of these coincide with observed stratospheric warmings during which east winds replace west winds, allowing for reflection of signal from the east at 40–50 km. The continuously high amplitudes result from reflection in the stratosphere where strong dissipation and tidal winds are minimal. Conversely when stratospheric westerlies diappear at times of warmings, infrasound from the Pacific diminishes at western stations, Continuous high-amplitude patterns not associated with an observed upper air warming are discussed as perhaps signifying unnoticed mesophere and lower thermosphere warmings.
On the growth of the pulsation threshold of a suppressed tone
Authors: Shannon Robert V.
Published: October 2005

Consider a 1200-Hz tone suppressing a 1000-Hz tone. For a fixed level of the 1200-Hz tone (50 dB) the pulsation threshold was measured at 1000 Hz as the 1000-Hz tone in the “masker” was raised from absolute threshold to 60 dB in 5-dB steps. When the level of the 1000-Hz tone was less than the simultaneous masked threshold at 1000 Hz the pulsation threshold measured was the same as if the 1000-Hz tone were not present in the “masker”. When the level of the 1000-Hz tone was raised above the simultaneous masked-threshold level the pulsation-threshold level increased at the same rate as the physical level—maintaining a constant number of decibels of suppression. When the level of the 1000-Hz tone was raised above the level of the 1200-Hz tone the pulsation-threshold level increased faster than the physical level, showing “recruitment” of pulsation threshold or a reduction in suppression. [Work supported by NINCDS.]
Modulation thresholds and temporal modulation transfer functions
Authors: Viemeister Neal F.
Published: October 2005

Temporal Modulation Transfer Functions (TMTF's) were obtained by measuring the threshold amplitude of sinusoidal modulation as a function of modulating frequency. For modulation frequencies below approximately 800 Hz, TMTF's obtained with a continuous wide-band noise carrier generally show the low-pass characteristic reported previously [J. Acoust. Soc. Am. 53, 314(A) (1973)], That is, with increasing modulation frequency the amplitude of modulation required for threshold remains constant up to approximately 10 Hz and then increases monotonically up to 800 Hz. The interpretation is that at high modulation frequencies the auditory system temporally “smooths” the amplitude fluctuations produced by modulation and the observer therefore requires greater modulation amplitude at the input in order to detect the modulation. For modulation frequencies greater than 800 Hz, modulation threshold is independent of modulation frequency and can be predicted from the increment threshold for wide-band noise. The form of the empirical TMTF generally agrees with that predicted by the familiar model consisting of half-wave rectification followed by “leaky integration.” The time constant of the integrator is estimated to be 3 msec. [Research supported by NIH.]
Dichotic listening in split brain subjects: Ipsilateral suppression reconsidered
Authors: Springer Sally P. , Sidtis John , Wilson Donald , Gazzaniga Michael S.
Published: October 2005

One current view of the mechanism underlying the ear advantage in dichotic listening has two components. The first is the relative superiority of contraolateral over ipsilateral auditory pathways, the second, the supression of ipsilateral information. While the notion of superiority simply implies an advantage for contralateral information, supression suggests that the information is unavailable. Three commissurotomy patients were given dichotic tests using consonant—vowel syllables and digits, as well as a binaural fusion test, in order to evaluate their ability to use information presented to the ear ipsilateral to the language hemisphere. Consonant—vowel syllables produced complete or near complete extinction of left ear information, while the digits test revealed a substantial increase in the use of left ear information. The fusion task produced performance greater than what would be expected by probability summation of the performance of each ear alone. The data suggest that in the absence of the corpus callosum, information from contralateral and ipsilateral ears can be integrated. Furthermore, the inability of the subjects to use information presented to the ipsilateral ear appears to be a function of the degree to which the competing items are acoustically similar, rather than a general suptession mechanism.
A musicologist's view of the teaching of musical acoustics
Authors: Kottick Edward L.
Published: October 2005

The teaching of musical acoustics has been dominated by those trained in scientific and technical fields. Many of these people are keenly interested in music and a good number of them are expert performers. But few of them are aware of the body of theoretical and historical knowledge about music that traditionally has been a part of the discipline of musical acoustics. As a result, some acoustical phenomena have been poorly understood and consistently misinterpreted. Scales, temperament, and the evolution of musical instruments are three of these areas. Each can be explained more satisfactorily when music history, music theory, musical style, and organology are taken into account.
Impedance calculations for musically useful horns
Authors: Dudley J. D. , Strong W. J.
Published: October 2005

A numerical method for calculating input impedance of a horn of arbitrary shape is described. The horn is approximated by a sequence of cylindrical sections, and an assumption of plane waves is made. The input impedance is calculated as a function of frequency for various bore shapes and sizes, including cones, cylinders, cone-cylinder combinations, and other Bessel horns, and resonant frequencies are determined. The results are compared to those obtained by analytical methods and to experimental measurements which have been reported in the literature. The effects of radiation impedance are discussed, and the relevance of these calculations to the study of musical wind instruments is considered.
Mathematical model for unpartitioned-cavity resonators
Authors: Sullivan J. W. , Crocker M. J.
Published: October 2005

In muffler design, concentric tube resonators are often used to provide high-frequency attenuation. These resonators are constructed by shaping a rigid shell around a length of perforated tube, forming an unpartitioned cavity. Because of the length of both cavity and perforated tube, it is not possible to use the simple Helmholtz resonator theory to predict the attenuation. Beginning with a one-dimensional control volume, a mathematical model was derived which accounted for the wave motion in the cavity and the coupling between cavity and tube via the impedance boundary of the perforate. For impedance in the linear regime, a closed form solution for the Transmission Loss was obtained. With this restriction and for the case of zero mean flow, excellent agreement was obtained with experimental results. Limited parametric studies suggest that the performance of this type resonator is quite sensitive to the porosity of the perforate, and that unusually large bandwidths of attenuation may be obtained for select geometires. [Work supported by Arvin Industries.]
Evaluating a two-channel lip-reading aid
Authors: Scott Brian L. , Filippo Carol Lee De
Published: October 2005

The lip-reading aid tested consisted of a vibratory channel and an electrotactile channel. The speech wave was low-pass filtered at 1000 Hz and presented to the palm via a Suvag vibrator and was high-pass filtered at 4000 Hz and delivered to the back of the hand by a bipolar pulse generator designed by Frank Saunders and built by R. M. Sachs. The electrotactile channel provides information about sibilants, bursts, and higher formants; and the vibratory channel provides rhythm, stress patterns, and other prosodic features. Subjects were two normally hearing adults listening to noise that masked the acoustic signal. Test materials consisted of nonsense syllables, words, sentences, and ongoing text, each set being used under three conditions: (1) lip reading alone, (2) lip reading plus vibrator, and (3) lip-reading, vibrator, and electrotactile stimulation. All tests showed that the vibrator with lip reading was superior to lip reading alone and that adding the electrotactile channel provided further benefit. The range of improvement in the vibrator-plus-lip-reading condition was 7–21%. Electrotactile stimulation provided an additional 2–10% improvement.
Acoustic study of speech in Parkinson's disease
Authors: Ludlow C. L.
Published: October 2005

Parkinson patients' speech was studied to determine which aspects differ from normal aging adult speech and what changes occur in speech when patients are in different neuromotor states—dyskinesia and rigidity. Parkinson patients alternating between dyskinesia and rigidity during dopamine enhancement treatment were recorded in each state while performing speech-imitation tasks presented on a test tape. Fundamental frequency, sound pressure level, duration and rate of syllables, and phrases were measured from spectrograms and power level tracings of the same speech segments in each recording. In contrast with the normal controls, Parkinson patients' speech during both dyskinesia and rigidity was reduced in length of extended phonation, rate of alternating between on-off phonation, and latency of vocal response. For fundamental frequency, speaking rate, syllable duration, and sound pressure level the degree of variation was reduced. The only speech measure differing between rigidity and dyskinesia was a lower sound pressure level during rigidity. The results indicated that Parkinson's disease significantly impairs laryngeal function and that only speech intensity level is affected by dopaminergic induced changes in neuromotor state.
Word verification in a speech understanding system
Authors: Cook Craig C. , Klatt Dennis H.
Published: October 2005

Given a word whose presence has been hypothesized in an unknown utterance, one way of enhancing the confidence in that hypothesis is to generate a synthetic parameterization of the word and then match it against the equivalent parametric representation of the unknown utterance. We have implemented such an approach in the speech understanding system under development at Bolt Beranek and Newman, Inc. Given a word, a synthesis-by-rule program generates a representation in terms of linear prediction spectra, which are matched against similar spectra of the raw signal using a 13-pole linear prediction error metric in conjunction with a dynamic programming time-normalization algorithm. Some automatic talker normalization procedures have been implemented in the synthesis strategy. The performance of the verification component has been measured by obtaining the distribution of verification scores for all word hypotheses generated by the speech understanding system, and determining the scores for words that should be verified correctly versus those scores for false word hypotheses. [Supported by ARPA under Contract No. N00014-75-C-0053.]
Statistical decision approach to the recognition of connected digits
Authors: Sambur M. R. , Rabiner L. R.
Published: October 2005

A connected digit recognition system that uses a statistical decision approach based on an expanded form of the principle of minimum residual error has been developed. The expanded distance measure includes the effects of analysis estimation error, the effects of coarticulation, and the effects of speaker variability. The recognition system has been tested on six speakers in a speaker dependent mode with recognition accuracies near 100%. It has also been tested with ten new speakers in a speaker independent mode, with a digit recognition accuracy exceeding 95%.
Applications of shock pulse technology to rolling element bearing condition monitoring
Authors: Howard P. L.
Published: October 2005

The Shock Pulse technique has been widely and successfully applied. Recent testing indicates its capability to determine bearing condition and lubrication condition in the presence of background machine noise. Examples of applications to helicopter gear box bearing monitoring will be presented as well as current data on other applications ranging from Railroad Car bearing to rocket engine turbopump bearing monitoring.
Efficient computation of array patterns
Authors: Anderson Victor C.
Published: October 2005

The impact of a symmetrical array geometry, the use of a quantized stored cosine function, the exploitation of Digital Fourier transform algorithms and the application of trigonometric interpolation in the computation of array patterns is discussed. Careful selection of parameters permits sampling the array pattern only 6% above the theoretical Nyquist limit. Reconstruction of array patterns showing −20, −30, and −40-dB relative interpolation errors are presented. A saving of 8000: 1 in computation time over direct “brute force” array pattern computation is illustrated for a hypothetical array. [Research supported by the Office of Naval Research and the Advanced Research Projects Agency.]