bluuebunny/crossref_metadata_2025 huggingface dataset:
Auditory brainstem electric response to click trains and continuous tones
Authors: Suter C. M. , Glaser E. M. , Goldberg A. , Dasheiff R.
Published: October 2005

This study was undertaken to investigate the effects of click interstimulus interval (ISI) and sensation level (SL) on the short-latency auditory-evoked potential (AEP), and the relation of the AEP and the frequency-following response (FFR). Continuous tones of 250 and 500 Hz and 0.1-msec acoustic clicks with ISI's of 250, 70, 17, 8, 4, and 2 msec were employed as stimuli at SL's of 70, 50, 30, and 10 dB. Both ISI and SL affect the AEP in a similar manner. A reduction in either results in an increase in response latency and a diminution of response amplitude. The relative effects are shown in terms of isolatency and isopotential curves for wave V. As the ISI becomes very short, the AEP becomes similar in waveform amplitude and threshold characteristics to the FFR to continuous tones.
Farfield recording of the frequency following response to the missing fundamental
Authors: Marsh J. T. , Smith J. C. , Brown W. S.
Published: October 2005

Subjects were presented with a complex stimulus consisting of four tones: 730, 1095, 1460, and 1825 Hz of equal intensity and cosine starting phase. For this stimulus 2f1−f2=f2−f1 = 365 Hz. Subjects perceived the 365-Hz combination tone and pitch matched it accurately to a pure tone at 365 Hz. Vertex to earlobe farfield recordings of FFR were obtained for both the complex stimulus and the 365-Hz pure tone. Both stimuli elicited FFR frequency of 365 Hz. Spectral analysis showed FFR to the “missing fundamental” larger than response to pure tone. Narrow-band noise with 365 Hz center frequency masked the pure tone but not the missing fundamental Noise reduced the amplitude of FFR to pure tone by 8 dB, but did not significantly affect FFR to the “missing fundamental.”
Three-way ERA system simultaneously collects ECochG, early and middle responses
Authors: Voots R. J. , Harker L. A. , Mendel M. I.
Published: October 2005

Laboratory investigations of electrical auditory responses are commonly categorized as early, middle, or late (latencies) and ECochG (electrocochleography). For clinical ERA with optimal use of patients' limited time, we have devised a three way combined system to collect, simultaneously on-line, data in three categories, independently, for a common stimulus set from a single array of electrodes. Two time-parallel early component channels are used, one for ECochG and one for brainstem responses (or optionally, both for brainstem responses from opposite sides of the head). A third channel collects middle responses. Conjunctly, we have also adopted a compound stimulus paradigm consisting of a click followed by a tone burst. This provides optimal stimulation for basal turn responses (early and ECochG) while also yielding frequency specific data from the middle responses. It also appears to provide an unexpected bonus by counteracting the myogenic (sonomotor) response that sometimes contaminates the middle neurogenic response. Data from ten young normal adults will be reported.
Method for increasing the number of beams from a time-domain beamformer
Authors: Stockhausen J. H. , Walkty L. D.
Published: October 2005

In a digital delay-and-add beamformer for a line array the number of beams that can be steered between broadside and endfire is equal to the travel time between elements divided by the sampling interval. This number is independent of the number of elements and if the array is long there may be insufficient beams to cover the directional space completely. Without increasing the sampling rate, additional beams may be steered by interpolating between successive samples from every second element. In typical cases the degradation of performance is insignificant.
Maximization of reverberation gain
Authors: Lee D.
Published: October 2005

The problem of maximizing array gain (AG) for situations where ambient noise is the dominant interference has already been extensively investigated, These investigations have resulted in mathematical solutions having significant promise for various practical applications. A closely related and more general problem arises when interference is dominated by reverberation; in this situation the gain against reverberation (the reverberation gain, RG) must be maximized. The same general mathematical approach can be applied to both problems in that the omnidirectional ambient noise limited condition can be considered a specific case of the more general directional ambient noise limited condition and the reverberation limited condition. Much of the existing theory has been directed at the specific cases thus leaving unfinished a comprehensive treatment of the general case. In this presentation, the complete RG-maximization problem will be addressed; a mathematical procedure to achieve the solution will be outlined; this procedure is developed with sufficient generality so that the maximization of AG is automatically included. An application of this technique is carried out for a three-dimensional array which demonstrates the validity and the effectiveness of this technique. [Work supported by NUSC.]
Who needs the octave—or, are standard bands feasible?
Authors: Maples L. C.
Published: October 2005

Although with the advent of the fast Fourier transform and digital filtering the constraints of available analog filter specifications are no longer really pertinent, the tendency to use the ANSI standard frequency bands for reference and comparison is widespread, particularly the so-called 13-octave bands. However, in problems involving complex spectra with shifting narrow-band components, it becomes obvious that the 13-octave approach is not adequate and may give misleading results, particularly at low frequencies, where the bandwidth is narrow. Similarly, because of their conceptual nature and also the way in which the bands are specified, consistent subdivision into narrow proportional bands is not possible, and such subdivision is now desirable, if not essential. For this reason, a return to the decimal system, in name as well as in fact, is strongly recommended. The problems encountered with standard “13-octave” bands are discussed in detail, in the context of the band specifications, and alternative methods of band specification, which avoid the problems entirely, are described, including a new look at the concept of “spectrum level.” [Work supported by NUSC.]
Interfrequency correlations of ocean ambient noise
Authors: Nichols R. H. , Sayer C. E.
Published: October 2005

The correlation of ambient noise levels in each of several frequency bands with those in other bands was investigated for an 11-12-day period in February with a hydrophone laid on the ocean bottom in deep water. The bandwidth for the measurements was 6 Hz; the center frequencies were chosen to cover the low frequency range in which shipping is generally the dominant source of noise, 10–150 Hz [G. M. Wenz, J. Acoust. Soc. Am. 34, 1936–1956 (1962)]. A total of 1562 consecutive 640-sec samples was taken in each frequency band; the average level for each sample was calculated and used in the computation of the correlation coefficients. Tonal line components were excluded. It was found that the coefficients of correlation between sample levels at a given frequency f0 and those at other frequencies generally decreased with increased frequency spacing, but the patterns differed for different f0's. Typical patterns will be shown. [Supported by IR&D program.]
Measurements of directional ambient noise
Authors: McConnell S. O.
Published: October 2005

Measurements of the directional ambient noise field have been made in a bay using an acoustic lens for which the beam pattern closely approximates a circular piston for the individual transducers (DI=28.7 at 25 kHz). The intensity radiation pattern of the noise at frequencies between 5 and 40 kHz is found and compared to models of the form sin2nθ where θ is the grazing angle and n=1, 2, 3. This form for the radiation pattern is used for comparison since previous measurements made at frequencies below 5 kHz can be fitted by a sin2θ pattern at frequencies above ∼ 500 Hz. Since the ambient noise at these frequencies appears to be generated at or near the sea surface due to such mechanisms as splashing of droplets, the intensity of the noise should be a function of conditions at the sea surface; a supposition borne out by these and previous measurements. Measurements are made of the wind shear and one-dimensional wave spectrum and related to the intensity of the noise.6 Measurements of the rate of rainfall and observations of intermittent noise sources are also made.
Noise generated by axisymmetric turbulent boundary layer flow
Authors: Lauchle G. C.
Published: October 2005

The noise generated by hydrodynamic flow over an axisymmetric body with a blunt nose is described quantitatively. Flush-mounted piezoceramic hydrophones were used to measure that part of the turbulent boundary-layer pressure fluctuations that propagates as true sound. Power spectra of the sound pressure were measured in a 3–50-kHz frequency range over a wide range of Reynolds numbers (U∞D/ν ⩽ 3.03 × 106, where D is the diameter of the body) for the model operating in the Garfield Thomas Water Tunnel. The use of flush-mounted hot-film probes to locate turbulence transition is also described. The power spectra of the noise measured in the laminar flow regions correspond closely to those measured in the transition and fully developed turbulent regions of the flow, The exceptions were those spectra measured on the flat part of the nose, but correction for diffraction loss effects suggests that the noise measured there is due to the noise generated by the turbulent part of the flow. Nondimensionalization of the noise spectra measured at various arc lengths with theoretical expressions for the noise expected, that include a critical boundary layer thickness at the beginning of turbulence, show a general collapse of data to within 6 dB. When applicable, comparisons of the radiated noise measured on buoyant bodies are made and agreement was found to be excellent.
Infrasonic flow-noise measurements using an H-58 hydrophone
Authors: Griffin O. M. , McGrath J. R. , Finger R. A.
Published: October 2005

Infrasonic and low-frequency flow-noise measurements were made during laboratory tests of an H-58 omnidirectional hydrophone. The hydrophone was tested in three configurations: bare, framed, and faired. Water speeds were varied from 0.25 to 0.45 knots and corresponded to a Reynolds number range from 8800 to 16 000. For different hydrodynamic reasons, the faired and framed configurations developed flow-noise levels lower than the bare hydrophone configuration. The bare hydrophone developed the highest noise levels at the lowest frequencies of the 1–50-Hz band. Hydrodynamic considerations related to the acoustic measurements made during this test are discussed; the importance of hydrophone configuration used in very low-frequency measurements is demonstrated.
Noise from cavitating hydrofoils as influenced by boundary-layer development
Authors: Blake William K. , Geib F. Ellsworth
Published: October 2005

This paper describes measurements of noise from cavitating flow over a hydrofoil. Cavitation was generated on a hydrofoil in the presence of a separated laminar boundary layer on the one hand and of a fully turbulent attached boundary layer on the other. The turbulent boundary layer was formed down-stream of a trip which was positioned near the leading edge. The noise is shown to depend on the type of cavitation produced. Dimensionless spectral densities of the sound are shown for each type of flow. For the cavitation associated with turbulent boundary layer development, the dimensionless spectrum is interpreted in terms of the observed single-bubble motions in the experiment.
Project SPAN 3: Low-frequency ambient sea noise in the South Fiji Basin
Authors: Bannister R. W. , Denham R. N. , Guthrie K. M. , Browning D. G.
Published: October 2005

Measurements of low frequency ambient sea noise near the New Zealand coast show relatively low levels due to a generally sparse shipping density in the Southern Hemisphere. [R. W. Bannister et al., J. Acoust. Soc. Am. 55, 418 (1974)] Project SPAN 3 extends these measurements to a deep ocean basin, specifically the South Fiji Basin located to the north of New Zealand. Ambient noise (10–500 Hz) was recorded continuously for one week on five hydrophones which were suspended between 300 and 2300 m depth in 4000 m of water. Supporting propagation loss measurements and ship density surveys were conducted. The results are in agreement with the previously reported data. [Work supported by NUSC and DSE.]
Radiation pressure—the history of mislabeled tensor
Authors: Beyer Robert T.
Published: October 2005

The acoustic radiation pressure has found practical application in recent years in instruments measuring sound intensity and in experiments on acoustic levitation. A historical review of the concept would therefore seem appropriate. The history of light radiation pressure goes back more than 200 years, beginning with Leonhard Euler and including such worthies as Maxwell, Boltzmann, and Lebedev. The concept of acoustic radiation pressure dates back some 100 Years, and its history features the names of Rayleigh, Poynting, Langevin, and Brillouin among many others. It was pointed out by Brillouin that what we call radiation pressure is not a pressure at all, but a diagonal tensor, all the diagonal terms of which are not identical. The size of the effect is small and the values obtained for the radiation pressure are very sensitive to boundary conditions and to approximations. In addition, although the phenomenon is one of nonlinear acoustics, it can be observed down to the lowest sound intensities under certain conditions. Thus, the Rayleigh radiation pressure vanishes for the linear case but the Langevin pressure doe not. It might be said that radiation pressure is a phenomenon that the observer thinks he understands—for short intervals and only every now and then. [Work supported in part by the Office of Naval Research.]
Acoustic levitation and manipulation for space application
Authors: Wang Taylor G.
Published: October 2005

The acoustics in space, apart from the obvious function of communication has branched out into many other areas of applications. The acoustical positioning device developed at JPL for manipulating and controlling liquid systems in a 0-g environment has the potential of becoming one of the most versatile tools for space research and applications. For example, in order to study the liquid drop systems originated from the Newton—Cassini controversy experimentally, we need a free suspended liquid drop without any dense medium surrounding it. Hence, both the 0-g environment and the acoustic manipulation chamber appear to be necessary. In order to carry out many of the processes for Material Science Laboratory in Space the melt is to be positioned and formed within a container but without making contact with the container walls. Electromagnetic methods of positioning and forming are limited to melts which are electrically conducting. The acoustical method is useful in the control of any moltem material including material that is electrically nonconducting. In this presentation, I will describe the principle of operation of this apparatus and the results of tests both in our laboratory and in the 0-g environment provided by the Johnson Space Center aircraft flights.
Acoustic levitation—a useful experimental technique
Authors: Crum L. A.
Published: October 2005

The nonzero, time-averaged acoustic force exerted by a sound field on a local inhomogeneity allows liquid, solid, and gaseous particles to be suspended in a fluid medium relatively free of physical restraints. This splendid isolation allows studies to be made of radiation pressure, rectified diffusion, damping constants, acoustic streaming, surface waves, and physical parameters of metastable states, as well as many other phenomena, that would be nearly impossible without it. A review will be given of the general technique, and of various ways it can be utilized to obtain experimental data. [Work supported by ONR.]
Preliminary account of some recent experiments on sound diffraction by barriers
Authors: Pierce Allan D. , Vidimos Robin A. , Hadden W. James
Published: October 2005

Experiments performed summer 1976 in an anechoic chamber at NASA Langley Research Center consisted of (1) diffraction around screen from point source not necessarily far from edge, (2) such diffraction when air is blowing parallel to screen sides with diffracting edge as trailing edge, (3) diffraction of noise from a jet of air exiting on one side of a thin screen, and (4) diffraction of sound around a barrier with curved top with radius of curvature larger or comparable to an acoustic wave-wavelength. These experiments were prompted by problems of assessing effects on aircraft noise when engines are mounted above wings. Accompanying theoretical work consisted of (1) generation of a convenient rapidly convergent numerical integration method for computation of Green's function given arbitrary sources and listener locations near a rigid wedge and (2) extension of Candell's solution of plane wave diffraction by screen in presence of ambient air flow to the point source case. [Work supported by NASA Langley Research Center.]
Noise control of the Standard Light Rail Vehicle
Authors: Spencer R. H.
Published: October 2005

The Standard Light Rail Vehicle (SLRV), currently being produced in quantity for Boston and San Francisco, has been designed to stringent interior and wayside noise criteria. The articulated joint in the carbody required an unusual design to reduce acoustic flanking paths. The average carbody transmission loss exceeded 30 dBA for the roof and sidewalls and was 35 dBA for the floor. The carbody design resulted in an interior noise level of 75 dBA at 40 mph, whether operating at grade or underground. Equipment noise levels were generally below 65 dBA at a distance of 15 ft from the track centerline. Acoustically damped wheels eliminated squeal on curves and resulted in 40-mph pass-by noise levels of 70 dBA at a distance of 50 ft from track centerline. Considerable appeal is expected by transit patrons, when the cars are introduced into revenue service.
Factors affecting the detection of mispronunciations
Authors: Cole R. A. , Jakimik J. A.
Published: October 2005

In a series of experiments, subjects were presented with sentences or short stories, and required to press a response key whenever they detected a mispronounced word. Mispronunciations were produced by changing one phonetic segment in a word to produce a nonword. Detection of mispronunciations was effected by factors at several linguistic levels: (a) the type of phonetic change, (b) the position of the changed segment in the word, (c) the stress of the syllable (e.g., “contain” versus “contour”, where /k/ was pronounced /g/ in each word), (d) the syntactic structure of the sentence, and (e) whether the word containing the mispronunciation occurred in a previous sentence. The results will be summarized and discussed.
Observations of buoyant plumes with monostatic acoustic radar
Authors: MacCready P. B.
Published: October 2005

Monostatic acoustic radar detects echoes from an artificial heated plume as well as from natural convective plumes; thus it has been used on occasion to ascertain the location, height, and thickness of the buoyant effluent from industrial sources. A brief-field investigation of an industrial source was conducted to compare, for stable lapse rate conditions: (1) the plume heights monitored with a mobile monostatic acoustic radar; (2) heights measured with an aircraft when the plume was temporarily marked by smoke, and (3) heights predicted by standard plume rise theory utilizing measured wind, temperature, and turbulence profiles. There was reasonable agreement between all three. Also the acoustic radar verified that the vertical thickness of the plume was as large as that assumed in the plume rise theory (namely, vertical thickness comparable to mean plume height above stack top). Heights predicted using standard plume rise theory, with meterological inputs extrapolated from surface observations rather than being measured aloft, were substantially lower than the observed heights. The plume turbulence and temperature gave sufficient acoustic scattering when the plume was near the final plume height (about 150 m) to avoid confusion with echoes from the ambient atmosphere.
Near-horizontal propagation of sound over grassland
Authors: Piercy J. E. , Donato R. J. , Embleton T. F. W.
Published: October 2005

An extensive set of published measurements of the propagation of noise from jet aircraft on the ground across an airport for differing weather conditions is compared with predictions using modern propagation theory from values of ground impedance, assuming an acoustically homogeneous atmosphere. When the atmosphere is in fact reasonably homogeneous under neutral weather conditions, there is quantitative agreement between calculated and measured behavior. The intricate pattern of acoustic behavior, as a function of frequency and distance, produced by inhomogeneous atmospheric conditions (gradients of wind temperature turbulence) is explained qualitatively by the appropriate modes of propagation revealed by the theory. The role of surface and sky waves in particular is illustrated.
Results from an acoustic sounder network study of the San Francisco Bay Area
Authors: Russell P. B. , Uthe E. E.
Published: October 2005

This study, begun in 1974, was expanded to a small network of three stations in 1975, with some additional data received from two sites operated by others. The measurements indicated widespread (up to 60 km inland) and frequency occurrence of a low (200–700 m) marine inversion, which was easy to detect acoustically. Records from San Jose could be usefully classified by the scheme developed in 1974 for Stanford—Menlo Park. They confirmed that the time of transition from near-surface stability to convection and the height of the inversion aloft (both as depicted by the sounder records) were equally important predictors of near-surface primary pollutant concentration. Records from Mt. Sutro (San Francisco) repeatedly showed a very intense inversion with the characteristic diurnal height variation (late afternoon minimum) revealed by a simultaneous direct-sensing study [A. Miller, Bull. Am. Meteor. Soc. 56, 52–55 (1975)]. Temperature profiles measured by tower, remotely piloted aircraft, and balloon at each site confirmed the inversion and convection behavior depicted by the sounder records. A 13-station network is starting operation in August 1976, to provide input data for an operational computer model of Bay Area air pollution. Preliminary results will be shown.
Theory of pulse spreading in dispersive random sound channels
Authors: Tappert F. D. , Dozier L. B.
Published: October 2005

The information-carrying capacity of underwater sound channels using a normal-mode, pulse-coded modulation scheme has been theoretically calculated. The effects of random internal wave fluctuations on signal propagation are taken into account. A pulse compression scheme is proposed to intensify received signals. The limiting factor is found to be random coupling between the acoustic normal modes due to scattering from internal wave modes. [Work supported by ONR.]
Applications of a full diffraction theory numerical simulation of sound propagation in the ocean
Authors: Fain G. , Estes L. E.
Published: October 2005

A review of this numerical technique and its physical basis is presented. A comparison of the technique and the parabolic approximation is made with particular attention paid to broad beam errors in the two approaches. The propagation is simulated in stepwise fashion with the range step sizes being limited by the Rayleigh length. The Rayleigh length is defined for a variety of different sound velocity profiles. The sensitivity of the technique to step size and sampling rates is examined by varying these parameters. The theory is extended to include smooth boundaries, sloping boundaries, and Snell's law bending in range (as well as depth). SOFAR channel, surface, duct, split beam shadow zone and sloping bottom are among the examples presented. [Work partially supported by the Office of Naval Research.]
Effect of Doppler on long-range sound propagation
Authors: Neubert Jerome A.
Published: October 2005

In this sound propagation study of the effect of Doppler on long-range acoustic tracking, a method of modeling the effects of source and/or receiver motion has been developed. It is based on modifying the inputs to existing normal mode software so that the source and/or receiver trajectory and consequent Doppler effects of the given ocean experiment are properly modeled without requiring direct changes in the static software. From this the effects of the received signal after long range, multipath sound propagation from a moving source can be modeled and interpreted.
Probability density functions for the amplitude of signals received from cw sources towed at long ranges in the deep ocean
Authors: Frisk G. V. , Giellis G. R. , Ramsdale D. J. , Flowers K. D.
Published: October 2005

The characteristics of the probability density functions for the cw tow data of the previous paper are discussed. Theoretical density functions which best fit the data and their physical interpretation are presented. The properties of the corresponding log transformed density functions are also discussed.
Correlation of predicted versus measured sound levels in naval surface ships
Authors: Feldman Samuel
Published: October 2005

The U. S. Navy and U. S. Coast Guard have jointly sponsored the development of an airborne noise prediction procedure for military surface ships, which was published in a report entitled “Handbook for Shipboard Airborne Noise Control” dated 13 February 1974. This paper is based on a study aimed at verifying the “Handbook” prediction procedure by comparison with full-scale, shipboard measurements. The U. S. Navy Spruance Class Destroyer (DD 963) offered an excellent opportunity for making such comparison. During the design phase, predictive calculations of sound pressure levels were made for all manned spaces. During the trials period airborne noise measurements were made in these spaces. The paper compares predicted versus measured sound levels in a limited number of spaces and also examines the source sound power level prediction formulae against measured power levels for various types of machinery. On the basis of this one ship sampling, reasonably good correlation was demonstrated between the predicted and measured sound pressure levels.
Time dependence of pitch perception-pitch step experiment
Authors: Hartmann W. M. , Blumenstock B. J.
Published: October 2005

In the pitch step experiment subjects tune an oscillator in three successive adjustments to match the pitch of a 15-msec sine-wave tone of frequency f2 that is immediately preceded by a 4-sec sine-wave tone with frequency f1 (900 <f1 < 1000 Hz) of the same intensity (82 dB). We find that for upward steps (f2 >f1) the matched tone frequency p2 tends to be greater than f2. This effect, whereby the pitch of tone 1 repels the pitch of tone 2 increases for decreasing |f2−f1|. The effect is reminiscent of the repulsion of a tone by a narrow noise band. [J. C. Webster and D. R. Muerdter, J. Acoust. Soc. Am. 37, 382–383 (1965)]. Therefore, a plot of p2−f1 versus f2−f1 is nonlinear (and possibly discontinuous) near the origin. If p2 is regarded as a description of the state of a pitch perceptor 15 msec after the step then the nonlinearity guarantees that no linear differential equation can describe the time-dependent response of the pitch perceptor. Dichotic experiments with tones 1 and 2 in different ears suggest that a repulsive-type nonlinearity is still present, though reduced in size. For downward pitch steps two of our subjects exhibit a repulsive effect (p2 <f2) and two subjects produce anomalously high p2 tunings.
Time dependence of pitch perception—vibrato experiment
Authors: Hartmann W. M. , Long K. A.
Published: October 2005

Subjects listened to diotic sine-wave tones (72 dB) with center frequency f0 (700⩽f0 < 900 Hz) frequency modulated at sub-audible rate v (0.5 < v 10 Hz). In a 2IFC experiment subjects decided whether the first or second tone of a pair of tones had the wider vibrato. One tone of the pair was made with sine-wave FM waveform; the other was made with triangle FM waveform. The sine-wave modulation excursion was fixed at Δfs = ± 20 Hz; the triangle wave excursion varied amongst the trials 0.8Δfs < ΔfT < 1.5Δfs. (In this range of v and Δf it is impossible to identify the FM waveform.) The subject judgments were analyzed by a least-squares procedure to determine a locus of subjective equality, ΔfT(v), for which vibrato widths due to the different modulations seem to be equal. The resulting locus unambiguously shows that pitch averaging takes place for such stimuli. For v < 7 Hz the locus of subjective equality can be reproduced by a model of pitch averaging with averaging-time constant of 130 msec, a factor of 10 greater than pitch recognition times. For v > 7 Hz a different averaging process appears to proceed. This simple model was tested by additional identical experiments with Δfs = ± 40 Hz and Δfs = ± 10 Hz. The model may survive these tests, but in the small v regime we find that the averaging time is approximately inversely proportional to Δfs.
Perception and production of double stops in violin playing
Authors: Zukofsky Paul , Miller Joan E. , Kohut J.
Published: October 2005

The playing of double stops (two notes produced simultaneously) was investigated to determine differences in reaction times and to consider the implications regarding the player's organization of information. Using a battery powered instrument equipped with metal strips placed at half-step intervals along the finger board, the violinist's performance was monitored by computer. Signals resulting from contact of the strings with the strips were sampled every 2 μsec to determine when which pitches were played. The player responded to stimuli consisting of double stops, single pairs of double stops and alternating pairs presented on a cathode-ray tube in conventional music notation. Reaction times were used as measures of ease in playing, for estimating perception versus motor times, and for examining the additivity of the processes involved. Preliminary findings suggest that (1) timings for single pairs depend upon the order of the members of the pair, and (2) the rank order of timings for single pairs correlates poorly with that of average speed for alternating pairs. The pedagogical significance will be discussed. [Work partially supported by IRCAM and the Rockefeller Foundation.]
Synthesis of chime tones
Authors: Fletcher Harvey , Bassett Irvin G.
Published: October 2005

Tones from three chimes were recorded and analyzed using a fast-Fourier-transform program. Three-dimensional, perspective plots were made of the sounds in order to determine the salient features. The analysis agrees well with that done previously by other investigators. Synthetic tones were produced by adding a series of sine waves with frequencies, amplitudes, and decay rates taken from the analysis. Listening tests were performed to evaluate the synthesis. Twenty subjects were presented a series of 30 tones consisting of three real and three synthetic sounds repeated five times in a random sequence. The subjects were asked to decide whether each tone seemed real or synthetic. Overall results for the 20 subjects were 55% right, just slightly above the level of guessing.
Vowel utterances of young infants
Authors: Stark R. E. , Heinz J. M. , Wright-Wilson C.
Published: October 2005

Syllable-like utterances produced by 14 different infants aged 1–40 weeks were presented to two trained listeners. The listeners first transcribed a portion of the data phonetically. They then compared transcriptions, attempted to resolve disagreements and decided upon conventions to be used. One hundred and twenty-two additional segments were then transcribed by the listeners independently. On 71% of these utterances the listeners disagreed in their transcriptions of syllabic nuclei. The remaining 29%, upon which they agreed, were all transcribed as mid or low front. Their judgments, where they disagreed, were always vowels adjacent to one another within the vowel triangle and were also predominantly heard as mid or low front vowels. The vowels at the extremes of the triangle, /a/, /u/, and /i/ were not judged to be present at all. Ten vowels upon which the judges agreed and ten upon which they disagreed were analyzed by conventional spectrographic and by computer-assisted spectral techniques. The results of these analyses will be discussed. [Work supported by NINCDS.]
Vowel spaces in two Kwa languages
Authors: Lindau Mona , Wood Patricia , LaFage Philippe
Published: October 2005

The acoustic spaces of two languages with seven vowel systems were compared. The languages were Yoruba and Ewe, both of the Kwa group of Niger—Congo languages. The vowels were /ieεaɔou/. The formant spaces were based on the production of several token of each vowel by four speakers of each language. While the seven vowels of Ewe are distributed in a highly regular fashion around the vowel space, this is not found in Yoruba, where the upper mid /e/ and /o/ are very close to the high /i/ and /u/, respectively. The phonetic differences between the two languages cannot be accounted for by any current theory of the utilization of the vowel space. The results indicate that the historical development of vowel systems is not only influenced by principles of maximal perceptual distance, or “base of articulation,” but may also be related to different phonological processes in different languages.
Voice fundamental frequency in saturation diving
Authors: Hollien H. , Hicks J. W. , Shearer W.
Published: October 2005

Divers under hyperbaric conditions experience a marked deterioration in speech intelligibility. Included among the possible features that contribute to speech degradation is speaking fundamental frequency (SFF). Based on the physics of the environment and the physiology of the diver, it would not be expected that SFF would vary due to HeO2/P conditions. However, in an earlier pilot study, increase in SFF was found. In order to test the cited hypothesis as well as expand the previous limited findings, a large group of U. S. Navy divers were studied. The diver/subjects produced speech at the surface and at depths of 200, 450, and 600 ft in helium-rich environments. Of the original pool of 46 divers, 28 were studied at 200 ft, 22 at 450 and 9 at 600 ft. The speech material used was the first paragraph of the Rainbow Passage; SFF was obtained by processing this passage by FFI-6. The raw data revealed a significant rise in fundamental frequency to 450 ft and a subsequent decrease at 600 ft, but subsequent analysis (based on the divers' SFF at the surface) showed an almost linear increase in SFF with increases in helium concentrate and ambient pressure. These results are discussed; it is believed that divers' attempts to speak “more intelligibly” (rather than the HeO2 environment) were the cause of this shift. [Work supported by ONR.]
Acoustic reflexes of middle-ear and laryngeal muscles in the FM bat Myotis lucifugus
Authors: Philip  , Jen H.-S. , Ostwald Joachim , Suga Nobuo
Published: October 2005

In Myotis lucifugus both the middle-ear muscles (MEM's) and the laryngeal muscles (LM's) are highly developed for echolocation. These muscles respond to acoustic stimuli with a shortest latency of 3 and 6 msec, respectively. The tuning curves of the MEM fibers are broader than those of the LM fibers. The lowest threshold of the acoustic reflex of the MEM's is 20 dB lower than that of the LM's. The majority of the MEM and LM fibers are tuned to sounds between 35 and 45 kHz. On the average, the LM fibers are 5 dB more sensitive to 4-msec FM signals sweeping downward 10 kHz across their BF's than to pure tones, but this is not true for equivalent upward sweeping FM signals. On the other hand, the MEM fibers show poorer responses to FM signals than pure tones, regardless of sweep direction, Electrical stimulation of the superior laryngeal nerve evokes action potentials in the MEM's with a shortest latency of 5 msec. The LM's and MEM's are apparently coupled through sensory fibers in the superior laryngeal nerve. [Work supported by University of Missouri summer research fellowship, Studienstiftung des deutschen Volkes, and NSF Grant 75-17077.]
Prediction of construction site noise
Authors: Brittain F. H. , Freytag J. C. , Chang H. C.
Published: October 2005

Prediction of construction site noise has generally been made by adding the highest noise levels generated by each piece of construction equipment. Worst case noise levels so predicted will overestimate actual noise levels. A technique has been developed to statistically (Ln) predict construction site noise from a list of construction equipment and an assumed duty cycle. The effect of finite source size is included. Measured construction site noise levels are compared with predicted noise levels.
Noise control for fan and vent shafts in subways
Authors: Lee Peter Y. N.
Published: October 2005

Subway fan and vent shafts can be significant sources of noise impact to both the adjacent community and to patrons in the subway stations. For fan shafts, the transmission of airborne noise through the shafts and surface openings to adjacent buildings and the transmission of noise through the subways to station platform are intrusive. For vent shafts airborne noise transmissed from trains passing by in the subway below to surface openings can be intrusive. The primary methods available for the reduction of fan and train noise propagated out shaft openings and fan noise propagated into the stations are (1) the use of acoustical absorption material on the interior surfaces of fan rooms, fan and vent shafts and tunnel walls and ceilings, (2) the use of sound attenuators [silencers] attached to the fans, (3) the use of specially constructed splitters in the fan and vent shafts or fan rooms, and (4) the use of acoustical louvers.
Experimental measurement of the modulation process involved in nonlinear interaction in water
Authors: Reeves C. R. , Goldberry T. G. , Olsen W. S. , Rohde D. F.
Published: October 2005

Nonlinear interaction between high and low frequency sound fields in water has long been modeled as phase modulation of the higher frequency by the lower frequency. For the modulation indices usually predicted, this implies the generation of side bands symmetric about the higher frequency having equal amplitudes but opposite phases. Simultaneous but independent measurements of the sidebands resulting from the interaction of a 65-kHz signal with low frequency signals from 100 Hz to 1 kHz now permit a direct comparison of the side bands for verification of the theory. Results are given for various frequencies, sound levels, and interaction geometries. [This research was supported by the Advanced Research Projects Agency of the Department of Defense and was monitored by the Naval Electronic Systems Command under Contract N00039-76-C-0231.]
Elastic properties of Tb0.3Dy0.7Fe2 measured ultrasonically
Authors: Blessing G. V. , Clark A. E.
Published: October 2005

Ultrasonic velocity and absorption measurements have been made as a function of magnetic field in both single crystal and polycrystalline Tb0.3Dy0.7Fe2. This highly magnetostrictive material exhibits a huge ΔE effect as previously reported at sonic frequencies. [A. E. Clark and H. T. Savage, IEEE Trans. Sonics Ultrason. SU-22, 50–52 (1975).] ΔE is the difference in Young's modulus between the magnetized and the unmagnetized state E0. In a polycrystalline bar sample, we measured an increased extensional velocity as a function of applied field (to 6 KOe) which corresponded to a ΔE/E0 of nearly 100%. A peak in the low field relative attenuation, with a corresponding velocity minimum, has been observed. These measurements were made at room temperature over a frequency range of 0.05 to 0.25 MHz. Bulk shear and longitudinal velocity measurements have been made from 1 to 21 MHz in both single crystal and polycrystalline samples. Measurements of sound propagation along [110] show that the crystal is elastically isotropic. Taking the density to be 9.25 g/cm2, at 12 MHz we calculate C11 = 11.7, 12(C11 − C12) = 3.84, and C44 = 3.84(× 1011 dyn/cm2). [Work supported by ONR.]
Monostatic cross section of a coated submerged hollow cylinder
Authors: Gaunaurd G. C.
Published: October 2005

An elastic hollow cylinder in water is coated with a viscoelastic and sound-absorbing material layer. We previously found [Proc. III US/FRG Hydroacoustics Symposium, Munich, May 1975. Vol. 1. Pt. 2, 4–31, and J. Acoust. Soc. Am. 58, S101 (A) (1975)] the classical Rayleigh series for the pressure field in the water for the case of plane-wave insonification at beam aspect, from which a series expression for the backscattering cross section was derived. We now present the numerical evaluation of these results at relatively low frequencies (ka ⩽ 20) in a lengthy and computerized parametric study. Using two size cylinders of interest, we analyze the effect of varying the coating viscosity, and the relative shell and coating thicknesses. The way in which the peaks in the oscillating cross section are shifted in frequency or damped-out in amplitude by changing geometries or materials, is useful to compute the coating effectiveness in reducing the target strength of the bare structure, a question of interest for design purposes. The high-frequency calculations remain to be performed using the Watson-Sommerfeld method.
High-frequency backscattering from marine zooplankton
Authors: Greenlaw Charles F.
Published: October 2005

It is often assumed that backscattering from marine zooplankton may be satisfactorily estimated from the Rayleigh fluid-sphere scattering model at frequencies such that ka < 1. At higher frequencies the fluid sphere model of Anderson [J. Acoust. Soc. Am. 22, 426–43 (1950)] has been thought approximately valid at least for the more spherical plankton. A series of acoustical and physical measurements was made on preserved specimens of three common zooplankters (a copepod, Calanus marshallae; an euphausiid, Euphausia pacifica; and a penaeid shrimp, Sergestes similis Hansen). Target strengths of individual specimens were measured in a freshwater tank at eight frequencies between 220 and 1100 kHz. Densities, compressional wave sound speeds, and displacement volumes of the samples were measured to enable calculation of predicted target strengths from the Anderson model. Measured target strengths of the copepod agreed with predictions up to ka = 1, but were increasingly higher than predicted up to the highest ka obtained (ka ∼ 4). The euphasusiid and sergestid were found to highly directional scatterers; anterior aspect target strengths were 10–20 dB lower than side or dorsal aspect values. Surprisingly, the general levels and gross structure of the side/dorsal aspect target strengths were in reasonable agreement with the Anderson model up to ka ∼ 11 (euphausiid) and ka ∼ 7 (sergestid). Data in the range ka ⩽ 1 could not be obtained for these plankters because of equipment problems. [Supported by ONR.]
Relation between creeping waves and normal modes of vibration of a curved body
Authors: Überall H. , Dragonette L. R. , Flax L.
Published: October 2005

The natural way for a disturbance to propagate over the surface of a smoothly curved, fluid-loaded elastic body is in the form of a series of damped circumferential (creeping) waves. Mathematically, the process is most conveniently described by a sum of normal modes, each characterized by a wavelength that fits the body's circumference an integer number of times. We demonstrate that any such mode will resonate at all those “eigenfrequencies” where the mode velocity coincides with the speed of one of the creeping waves. For an elastic cylinder, the 180° sound-scattering amplitude is shown to possess marked minima at many of the eigenfrequencies, whose spacing over a sequence of modes thus determines the group velocities of circumferential pulsed signals. [Work supported by ONR.]
Amplitudes of transmitted and circumferential waves in sound scattering from an elastic cylinder
Authors: Dickey J. W. , Überall H.
Published: October 2005

The phenomenon of sound scattering from a smoothly curved, submerged elastic body involves two different mechanisms, namely (a) geometrical reflection, refraction and multiple internal reflections and (b) diffracted fluid-type and elastic-type surface waves. These have previously been studied individually [(a) Brill and Überall, J. Acoust. Soc. Am. 50, 921 (1971); (b) Frisk, Dickey, and Überall, J. Acoust. Soc. Am. 58, 996 (1975), and (in press)] for the case of an aluminum cylinder in water, obtaining dispersion and absorption curves for the diffracted field. We now evaluate the amplitudes of both (a) and (b) and compare their relative: strength for values of ka (k is the wave number and a is the cylinder radius) from 25 to 200. While the lower-order geometrical contributions are generally larger than the diffracted ones by an order of magnitude, some of the latter may surpass the former, and the relative elastic-type (Rayleigh etc.) surface-wave amplitudes do not markedly decrease with ka while the fluid-type waves (Franz, Stoneley) do, We have searched for resonances in the surface-wave amplitudes, possibly related to mode resonances at their eigenfrequencies.
Shear waves in unconsolidated sediments
Authors: Shirley D. J. , Anderson A. L.
Published: October 2005

The dynamic shear modulus of unconsolidated marine sediments is small but nonzero. Shear waves will propagate in the sediments, but only at very slow speeds. The compressional wave speed is increased as much as 5% by the nonzero modulus. As a suspension of clay particles settles and collects into a gel-like material, the dynamic shear modulus increases. This initial development of sediment frame structure has been observed by measuring shear wave speed. Several stages in the development process can be described from these results.
Acoustical environment in the open-plan office
Authors: Harris D. A.
Published: October 2005

ASTM E-33.04C Committee on Environmental Acoustics, Applications Subcomittee, Task Force on Open-Office Acoustics, has prepared a publication entitled, “Acoustical Environment in the Open-Plan Office.” The purpose was “ … to assemble and explain recent references on the acoustical design and testing of open-plan offices. The principles contained may be used by the Committee to prepare applicable ASTM standards and recommended practices for the acoustical evaluation of open-plan office systems.” The paper deals with the “ … acoustics of the open-plan office in a way that clarifies the principles that designers and architects use to achieve an acceptable and flexible environment.” It covers privacy criteria and theory, how open office components affect the acoustical environment, a discussion of appropriate testing procedures, and a summary of acoustical design parameters. A summary of the paper as published in ASTM Standardization News will be presented.