bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-component data windows for digital spectrum analysis
Authors: Burgess J. C.
Published: October 2005

Digital spectrum analysis of periodic signals can easily result in inaccurate estimates for harmonic component amplitudes [J.C. Burgess, “On digital spectrum analysis of periodic signals,” J. Acoust. Soc. Am. 58, 556–567 (1975)]. Use of a properly selected data window can improve accuracy in uncorrected displays, partly by reducing amplitude variation and partly by reducing leakage. A two-component data window is one having the functional form b(t) = B0 + B1 cos2πt/T, where T is the record length. Witkin the limits imposed by taking only two components, the coefficients B0 and B1 can be chosen to minimize the effective major spectral lobe width when a realizable criterion of major lobe magnitude to next greatest lobe magnitude is chosen. Two well-known (normalized) data windows, hanning (B0 = 0.5, |B1| = 0.5) and hamming (B0 = 0.54, |B1| = 0.46), are examples of special interest.
Doppler tracking performance
Authors: Friedman A. J. , Spooner R. L.
Published: October 2005

The performance of a narrow-band passive acoustic tracking system utilizing Doppler frequency shift depends upon both the sensor field geometry and the accuracy with which frequency shifts may be estimated. In general, there exists a relationship between these two factors independent of the implementation of an actual processing system. The characteristics of this relationship are presented in this paper with specific performance bounds being obtained for typical sensor field geometries. It is shown that for frequency estimation accuracies obtainable with currently available hardware, and within the constraints of available signal-to-noise ratio, sensor field geometry becomes the major determinant of tracking performance.
Acoustic radiation from pipes, excited by internal turbulent flow: Comparison of experimental results with theory
Authors: Rennison D. C. , Bull M. K.
Published: October 2005

The analysis of acoustic radiation from piping systems is complicated by the presence of multiple excitation sources; for example, mechanical valve vibration, acoustic near- and farfields, and the random pressure field of fully-developed turbulent flow will normally act together. This latter pressure field is well defined, and was chosen as the excitation for an initial parametric investigation of the response of and radiation from piping systems. An intermittent induced-flow pipe facility, mounted across an anechoic chamber, was used to obtain extensive measurements of the radiation from steel and P.V.C. pipes for a wide range of flow speeds and several pipe wall thicknesses. Theoretical predictions compare favourably with experimental measurements. The main conclusions are: the acoustic power radiation is resonant and well-described by considering only acoustically fast pipe vibration modes; this radiation is proportional to the modal loss factors and to the fifth power of flow Mach number. Comparisons between excitation by fully developed flow and propagating acoustic fields are given, which demonstrate their relative importance.
Structure of a phonological component for a synthesis-by-rule program
Authors: Klatt Dennis H.
Published: October 2005

A synthesis-by-rule program can be thought of as a functional model of human sentence production. The phonological component of this model accepts as input a linear string of symbols that have been produced by the semantics component, syntactic component, and lexical component of a grammar of English. This abstract representation of an utterance is transformed by the phonological component into a phonetic transcription and a specification of the fundamental frequency contour, segmental durations, and stress levels. This paper will discuss the structure and detailed representation of information in a computer simulation of a phonological component and propose a programming language for stating phonological rules. [Supported in part by an N.I.H. grant.]
Rules for irregularities in speech production of American English
Authors: Coker C. H. , Webber S. A.
Published: October 2005

General rules for production of English phonemes may be studied very effectively by statistical methods. The rules have numerous exceptions, however, involving special treatment of sometimes infrequently occurring conditions. The problem is to identify these exceptions, and then to find enough examples to characterize them. Speech synthesis is especially suitable for this kind of exploratory study. When synthesized utterances are substantially correct, exceptions stand out clearly, as mispronounced words. In our synthesis, a program for regular timing and allophone selection is followed by a set of rewriting rules to handle exceptions. In using the system, when utterances are found for which the rules are inadequate, the program allows quick examination of similar phrases, and interactive editing at the segment level to evaluate potential rule changes. New rules are easily added, or existing ones further qualified. Using this method, we have developed quantitative rules for nasal assimilation, flaps, changes within cluster, syllabic consonants, context-dependent vowel glides, and other adjustments to prevent devoicing and slurring of weak syllables. The rules are nonrecursive, LR1 at the segment level, and programmable in about 80 FORTRAN logical IFs. The oral paper will summarize these rules. Part of the presentation will be in synthetic speech.
Perceptual dimensionality of jitter and shimmer in synthetic vowels
Authors: Rozsypal A. J. , Millar B. F.
Published: October 2005

Dimensionality of the perceptual space of synthetic vowels /a/, /u/, and /i/ with different amount of jitter (randomness in vocal period) and shimmer (randomness in vocal amplitude) was investigated. Using the method of paired comparisons, the subjects were instructed to select the more human-like vowel sound in each pair. The preference data was analysed using an analysis of variance and multi-dimensional scaling techniques. The results support the observation that some degree of roughness is necessary for vowels to be perceived as natural. The multi-dimensional scaling yielded a two-dimensional solution which was not readily interpretable in terms of the signal parameters.
Performance and noise evaluation of an axial flow fan design with various blade tip shapes
Authors: Pisarski John J.
Published: October 2005

Detailed tests were conducted on standard shape axial flow fans as well as blades with tip treatment. The object of the tests was to determine the optimum tip configuration. To evaluate the effect of changes in trip clearance, the tests were performed with a blade to shroud clearance of 0.5 and 0.75 in. All other system and environmental factors were held constant. The test facility was designed to standards based on a recently developed induct sound power measuring system which includes a measuring section for fan performance measurements, a microphone system consisting of a microphone with attached sampling tube developed to handle crossmodes and suppress flow noise, and a nearly anechoic termination to deal with the problem of end reflections. The measured data compares aerodynamic performance, specific sound characteristics, radial distribution of velocity components, and the noise spectra at various operating conditions. The results indicate that fan tip design has a significant influence on fan performance and fan noise.
Development of guidelines for environmental impact statements
Authors: von Gierke H. E.
Published: October 2005

The legal requirements and general guidelines for Environmental Impact Statements (EISs) in general and for EISs with respect to noise specifically are reviewed. The approach of a CHABA working group charged with recommending guidelines for the preparation of EISs with respect to noise is reported and the technical problems encountered in this task are presented with the hope of stimulating discussion and inputs to facilitate the development of a satisfactory, generally acceptable consensus procedure.
Lateral waves and low-frequency negative bottom loss
Authors: DiNapoli F. R.
Published: October 2005

Many of the recent low-frequency bottom loss experiments, although conducted by different investigators in diverse geographical locations and using different experimental procedures, have resulted in the paradoxical observance of “negative”, bottom loss values. It has been conclusively shown in the previous paper that artifacts of the experimental procedures need not be the explanation for the anomaly. The contention of this paper is that the “negative” loss anomaly results from the application of models which do not account for the time coincident interaction of ocean bottom reflected energy with subbottom energy returning to the water column. This hypothesis will be supported by presenting and discussing a Fast Field Program (FFP) time domain simulation where the lateral wave is the only additional arrival interacting with the arrival of the reflected wave. [This work was sponsored by Naval Sea Systems Command, SEA 06H1-4, A.P. Franceschetti.]
Hidden depths: Acceptable ignorance about ocean bottoms
Authors: Williams A. O.
Published: October 2005

To determine, for normal-mode calculations of low-frequency propagation, a depth in the ocean bottom below which physical parameters can be ignored, four steps are proposed. (1) Postulate a model, interrupted at depth h by a horizontal plane reflector. (2) Specify acceptable fractional errors in mode eigenvalues. (3) From the eigenvalue equation, find the corresponding allowable deviation(s) of normal acoustic impedance at the interface(s). (4) Determine h so that effects of removing the reflector are within the deviation(s): below this h, parameters need not be known. Results are shown for two simple models: a “fast” isovelocity bottom and one with a positive gradient of sound speed. The deep overlying ocean is approximated as isovelocity (permissible because the chief pertinent modes are bottom-reflected ones). Values of h are typically a few acoustic wavelengths for eigenvalue errors of 10−6. Depite its importance in long-range propagation, absorption appears to affect h only slightly. [Work supported by Naval Electronics Systems Command.]
Mode enhancement using a vertical array of transmitters: Theory and experiment
Authors: Kanabis W. G.
Published: October 2005

A vertical transmitting array was implanted in Block Island Sound in November 1970. Tests conducted in 1972 and 1973 in the Block Island area used this array to transmit energy at 1700 Hz and used a vertical array of receivers to probe the sound field in range and depth. The measurements served as a test of the possibility of enhancing selected modes in the sound field by weighting the transmitting array elements in a manner which matched the field of a selected mode. In addition, they tested the ability of an acoustic model to predict propagation loss as a function of range and depth for a vertical array of sources. Long-term oceanographic data were also taken using temperature sensors attached to the tower containing the transmitting array. These data were used to determine both the long- and short-term temporal stability of the medium and the resulting effect on mode enhancement as a function of frequency. [This project was funded by NAVSEA (SEA 06H1-4).]
Electrical impedance changes in the guinea pig cochlea recorded during tonal stimuli
Authors: Geisler C. D. , Adrian H. O. , Mountain D. C. , Hubbard A. E. , Ravindran A.
Published: October 2005

A new method for measuring electrical impedance changes that are elicited by tonal stimuli in the cochlea of the barbiturized guinea pig has been developed. Constant currents of low-frequency sinusoidal waveform are delivered to scala media simultaneously with tonal stimuli. Voltage recorded from scala media at a frequency equal to the sum (or difference) of the applied frequencies is proportional to the amplitude, ΔZ, of the fundamental component of the impedance change synchronized to the acoustic waveform. ΔZ's observed range from approximately 0.5% of the total impedance for 90-dB stimuli to the noise level, near 0.01%. Complicated relationships exist between ΔZ and the cochlear microphonic (CM). Both ΔZ and CM behave identically as a function of tonal intensity at low frequencies. However, ΔZ varies differently from CM as frequency changes, probably due to CM leakage from other turns. Under hypoxic conditions, the observed change in ΔZ is a very slow decay corresponding to the second phase of CM change. [Work supported by NIH research grant 5-PO1-NS-06225 awarded by NINCDS, PHS/DHEW.]
Temporal summation of masker energy in forward masking
Authors: Feth L. L. , O'Malley H.
Published: October 2005

Recent investigations [M.J. Penner and E. Cudahy, J. Acoust. Soc. Am. 54, 1530–1534 (1973); M.J. Penner, E. Cudahy, and G.W. Jenkins, Percept. Psychophys. 15 (1974)] have indicated that masker energy is summated ever several decades of time when a filtered click probe is presented following a burst of bandlimited noise. Penner et al. have inferred temporal energy summation from the 10-dB increase in probe level at threshold for each decade of increased masker duration. In order to test directly masker energy summation, a change in masker duration should be compensated by an appropriate change in masker level so that constant energy is maintained in the masking burst. We have investigated the forward masking of such “constant energy” maskers for stimulus conditions similar to those of Penner et al. For most of these conditions, constant energy maskers do not appear to produce equivalent masking. In fact, preliminary results suggest that brief maskers produce approximately 5–7 dB less masking than equivalent energy maskers of 10 times their duration. [Work was supported by a Purdue Research Foundation Faculty Summer Research Grant awarded to the first author.]
Comparison of phase effects in masking obtained from broad-band and narrow-band frozen noise waveforms
Authors: Bell D. W. , Becker B. W.
Published: October 2005

In a paper presented at the 89th Meeting of the ASA, Bell and Becker [J. Acoust. Soc. Am. 57, Suppl. No. 1, S37(A) (1975)] reported masking data that were obtained using a 500-Hz sinusoid embedded in a set of 50 msec “frozen” noise waveforms that had been low-pass filtered at 4 kHz. The phase relationship between the 500-Hz sinusoid and the noise microstructures was manipulated through four 90° steps. In a subsequent paper, Becker and Bell [J. Acoust. Soc. Am. 57, Suppl. No. 1, S37(A) (1975)] noted the limited success of their attempts to predict that psychoacoustic data using a number of current models of the process humans use in detecting sinusoids in noise. This limited success is in contrast to the simple lawfulness of data reported by Doland obtained with bandlimited noise. Masking data are presented using the same set of waveforms, but digitally filtered to produce 200-Hz bandpass noise centered at 500 Hz with 40 dB/octave slopes (and Butterworth characteristics). The psychoacoustic data obtained with the filtered waveforms, and modeling of that data, are reported. Differences between the current data, the Bell and Becker data, and the Doland results are discussed along with the implications of the data for the critical-band concept.
Effectiveness of speech and noise maskers on numbers embedded in continuous discourse
Authors: Young Lamar L. , Parker Cheryl , Carhart Raymond
Published: October 2005

We investigated whether backward and forward speech produce identical masking when the target demanded prolonged or complicated integration. The target signal was a tape recording of continuous discourse with two-digit numbers embedded at 10-sec intervals. This target signal was presented in the presence of eight maskers: (1) two and four talkers speaking continuous discourse containing numbers; (2) two and four talkers speaking continuous discourse not containing numbers; (3) two and four talkers speaking connected discourse that was reproduced backwards; and (4) two and four talkers modulating a filtered noise. The presentation level of the target signal was 60 dB SPL. The intensity of the masker was varied to yield signal-to-competition ratios of −8, −3, +2 and +7 dB. The results suggest that forward speech was the most efficient masker, then backward speech; and finally, the modulated noise was the least efficient masker.
Pure-tone intensity and frequency discrimination as a function of frequency and sensation level
Authors: Wier Craig C. , Jesteadt Walt , Green David M.
Published: October 2005

The most frequently cited data on intensity and frequency discrimination as a function of both frequency and sensation level are from Reisz (1928) and Shower and Biddulph (1931), respectively. Both of these experiments used modulated tones. Evidence has accumulated that the discriminable change is different for modulated and unmodulated tones. In the present experiment a 2IFC-adaptive procedure was used to estimate both ΔI and ΔF at eight frequencies from 200 to 8000 Hz and at five sensation levels from 5 to 80 dB. Subjects listened to 500-msec pure tones presented in low-level broad-band noise. Intensity discrimination was constant as a function of frequency, showing the same “near miss” to Weber's law at all frequencies. Frequency discrimination showed effects of both frequency and sensation level. [This research was supported by the National Institutes of Health.]
On the successive stages of flow noise generation
Authors: Peter Abraham C.
Published: October 2005

The physics of flow noise generation is discussed and a qualitative survey of the successive stages of noise formation is presented in terms of the energy transport equations of acoustic waves. Initially, an acoustic wave, whose energy transport characteristics are assumed known, is subject to dissipative thermodynamic processes. The resultant frictional heat input into the fluid causes a continuous steepening of the entropy gradients and an eventual collapse of the disturbance, thus inducing mixing of the fluid strata. From the thermodynamic aspect of these phenomena, the mixing processes may be viewed as consisting of two parts. First, an expansion of the fluid takes place, due to the elevated pressure at the end of the frictional heat input. This expansion process, which brings the pressure of the fluid back to its ambient surroundings, is itself a source of an ideal, acoustic secondary wave, since its thermodynamic nature is purely nondissipative. Subsequently, the fluid attains thermodynamic equilibrium by means of an isobaric contraction process. By an analysis of the wave energy terms, it is shown that it is the frictional collapse and its resultant sudden expansion, which constitute the main acoustic flow noise sources.
Speech perception in early infancy: Discrimination of speech-sound categories
Authors: Kuhl Patricia K. , Miller James D.
Published: October 2005

The sucking-habituation technique was used to test 4- to 16-week old infants' tendencies to discriminate changes in formant frequency (synthetic /a/ vs /i/) in the presence of irrelevant variation in the pitch contour of the stimuli, and their tendencies to discriminate changes in pitch contour (steady vs rise-fall) in the presence of irrelevant variation in the formant frequencies of the stimuli. Analysis of the sucking rates for the 2 min preceding and the 2 min immediately following the fulfillment of the habituation criteria for experimental (stimulus change) and control (no stimulus change) infants demonstrated discrimination of formant changes regardless of the presence or absence of irrelevant variation in the pitch contour of the vowel. While infants demonstrated discrimination of the pitch-contour change in the absence of an irrelevant change in the vowel, they did not discriminate the pitch change in the presence of an irrelevant change in the vowel. It took longer for infants to meet sucking-habituation criteria when an irrelevant dimension was varied. Infants ran as “silent controls” produced fewer high-amplitude sucks than infants for whom sound presentation was contingent on high-amplitude sucking [Supported by NIH Grant NS 03856 to CID.]
Temporal processing in noise by persons with noise-induced and age-related hearing loss
Authors: Cudahy Edward A. , Elliott Lois L.
Published: October 2005

A variety of tasks, using a 21FC procedure, were employed to investigate auditory temporal processing in noise by hearing-impaired and normal listeners. First, temporal integration functions were measured in wide-band noise for tonal durations ranging from 3 to 985 msec at 500, 1500, 2000, and 4000 Hz. Second, detectability in the presence of a continuous narrowband (400–800 Hz) noise masker was measured for 5- and 146-msec tonal signals at six frequencies from 500 to 4000 Hz. Finally, forward masking, backward masking, and gap masking were studied for a 5-msec 1500-Hz signal and a narrow-band (400–800) noise masker. For gap masking, the masker was continuous except for a brief silence or “gap” of 20-, 50-, or 200-msec duration during each observation interval. Several general trends emerged from the data. First, all hearing-impaired subjects showed poorer than normal temporal integration at frequencies where their audiometric loss was greater than 40 dB. Second, listeners with noise-induced hearing loss exhibited the greatest upward spread of masking in the continuous masker condition. Third, forward masking functions showed no major differences between groups of listeners. Finally, subjects with noise-induced hearing loss tended to display greater masking than normals in backward- and gap-masking conditions, whereas this was not so obvious for subjects with sloping, high-frequency hearing loss. Results are discussed in terms of contemporary models of auditory temporal processing.
Genetic factors in hemispheric specialization for speech: A preliminary study of dichotic listening in twins
Authors: Springer Sally P. , Searleman Alan
Published: October 2005

The present study examined the contribution of genetic factors in the determination of hemispheric specialization for speech. Seven right handed monozygotic and seven right handed dizygotic female twin pairs were tested with a 240-pair consonant-vowel dichotic listening test. A comparison of intrapair variability for the two groups on a measure of ear advantage derived from the dichotic task showed that the dizygotic twins were significantly more variable. These results support a model of cerebral organization in which patterns of hemispheric asymmetry are genetically coded.
Performance of males and females on a dichotic listening task
Authors: Thistle Anne B.
Published: October 2005

Forty-eight right-handed, paid volunteers, 24 males and 24 females, participated in a 480-trial dichotic listening task, using the natural syllables /pa, ta, ka, ba, da, ga/. Subjects were screened for symmetrical hearing by pure-tone audiometry. Earphone orientation and order of presentation were counterbalanced. Although the trend noted by previous authors [Johnson and Ryan, J. Acoust. Soc. Am. 57, S24(A) (1975); Remington, Krashen, and Harshman, J. Acoust. Soc. Am. 55, 434 (1974)] for males to show larger right-ear advantages was present, t-tests revealed no significant differences between males and females on percent of errors contributed by the left ear, laterality index {100×[(right correct − left correct)/(right correct + left correct)], figured over single error trials only}, or absolute value of the laterality index, figured over all subjects or over only those showing significant ear advantages.
Stop and vowel identification from acoustic segments of VC and CV syllables
Authors: Ohde Ralph N. , Sharf Donald J.
Published: October 2005

This study involved the identification by nineteen subjects of stops /p,t,k,b,d,g/ and vowels /i,u,ɜ̆/ from the acoustic cues of noise, transition, noise and transition, and transition and vowel which were edited from VC and CV syllables. The major findings are (1) vowels were identified from consonants better than consonants were identified from vowels (99% vs 52%); (2) vowels were identified from transitions better than were consonants (99. 3% vs 45. 6%); (3) R to L identifications of vowels from noise were greater than L to R identifications (73% vs 39%); (4) R to L and L to R identifications of vowels from transitions and from transitions plus noise were very high (at least 99%); (5) there was little difference in the identification of stops from noise cues in CV and VC syllables (97% vs 96%); (6) there was little difference in the R to L and L to R identification of consonants from transitions (46% vs 44%); and (7) R to L identification of consonants from transition and vowel was greater than L to R identification (66% vs 39%). The implications of the findings were considered with respect to perceptual models, in particular, those relating to vowel transitions, masking, and coarticulatory effects.
Experimental studies of insulation from aircraft noise
Authors: Quirt J. D.
Published: October 2005

In 1972, the National Research Council was consulted in the preparation of guidelines for the design of residential construction near airports. An experimental study was undertaken to determine the performance of exterior walls and roofs, and to compare insulation against an isolated source such as an aircraft with that obtained for the reverberant sound fields used in conventional laboratory measurements. A composite structure that embodied the main features of typical Canadian housing units was constructed in the NEF 40 zone on an approach path to Ottawa Airport, where it is exposed to noise from a wide variety of aircraft during routine operations. In addition, a Jetstar aircraft was made available for special flights on the four sides of the house to permit a study of the effect of aircraft position on the noise reduction. Several varieties of windows, doors, exterior walls, and roofs were tested, together with tests of special components such as ventilator fans and fireplace flues. First results of the outdoor studies are in agreement with estimates in the guideline document.
Experimental study of impulsive sound-level response statistics in a reverberrant enclosure
Authors: Lambert R. F. , Dunens E. K.
Published: October 2005

Many industrial noise sources exhibit strong impulse behavior and operate in a reverberant environment. The sound pressure response to this type of source is not adequately described by steady-state formulations when the responses to successive noise impulses are nonoverlapping. An experimental study has been made to assess the influence on the pressure response of such factors as source-receiver location, amount and placement of sound absorbing material, and shielding by barriers. A spark gap serves as a controllable impulsive noise source. The measured responses are the rms sound pressure and its absolute level together with its exceedance probability distribution (EPD). The rms sound pressure relates to the total energy at the receiver while the EPD relates to the time variation of the response sound pressure level. Additionally, the EPD can be used to assess compliance with noise regulations that involve a time exposure. Results of source changes (location, impulse occurrence rate) and enclosure modifications (addition of sound absorbing material or barriers) are presented. [Work supported by NSF Grant GK 4340.]
Enclosure internal acoustic environment as influenced by size of contained bodies
Authors: On F. J.
Published: October 2005

An analysis procedure is presented for predicting the effects of the size of contained bodies on enclosure internal acoustic environments. The procedure was applied to predicting the effect of payload configurations on the Shuttle orbiter payload bay lift-off internal acoustics. Presented in this paper are the details of how the study was performed, and a discussion of the most pertinent results, such as the effect of payloads on acoustic modal density and overlap, noise reduction, relative level between payload occupied and empty condition, absolute internal acoustic noise level, and overall level. From the results presented, an approximate assessment can be made of the extent that payload configurations can affect the acoustic noise environment in the Shuttle orbiter payload bay.
Noise suppression by an acoustically treated three-ring inlet on a TF-34 engine
Authors: Minner G. L. , Goldman R. G. , Heidelberg L. J.
Published: October 2005

Acoustic performance tests were conducted with a three-ring inlet noise suppressor designed for a TF-34 engine. For all tests the aft noise sources were highly suppressed. The measured inlet suppression was large, reaching levels greater than 30 dB at the peak. Comparisons between the data and performance predictions were in reasonably good agreement. The frequency of peak attenuation was well predicted, while the magnitude and spectral shape were reasonably well predicted. This good agreement occurred when the distribution of sound energy across the inlet was taken into account in the performance predictions. Tests in which the length of treatment was varied showed an orderly progression of attenuation with length. The performance predictions for the different lengths also showed an orderly progression with length. At the highest speed of the engine, multiple pure tones were present throughout the spectrum in the source noise signature. These tones were very effectively suppressed by the inlet liner, even at low frequencies, while the liner was designed to work best at blade-passing frequency.
Analytical-numerical method for the treatment of radiation from elastic structures I. General theory. II. Application to free-flooded ring transducers
Authors: Gonzalez M. A. , Barach D.
Published: October 2005

Finite element methods have been used by several authors to study the problem of acoustical radiation from elastic structures [M.R. Knittel and D. Barach, Naval Undersea Center TP 412 (July 1974), and references contained therein]. The radiation loading of the structure due to the fluid medium can be taken into account either by numerical techniques based on the Helmholtz integral equation, or by additional finite element modeling of some of the liquid out to a separable surface where impedance conditions can be written in closed form. In this work we extend this method to the problem of radiation from multiple structures, either passive or active. Finite elements are used to model the scatterer and/or projector, as well as that portion of the liquid medium between the structure and a sphere completely surrounding it. The multiple-radiation problem is then handled using the methods developed by Twersky and others for conventional boundary-value problems [V. Twersky, “Scattering by Two Objects,” in Electromagnetic Waves, R.E. Langer, Ed., Univ. of Wisconsin P., Madison, WI (1962)]. As an application of the method we have analyzed the radiation from two tangentially polarized, ceramic free-flooded rings. Directivity, source levels, and electrical impedance have been calculated for a range of frequencies. Comparison with experiment show very good agreement over the frequency band of interest.
Experimental investigation of shear waves in laboratory sediments
Authors: Shirley D. J. , Anderson A. L.
Published: October 2005

Transducers for the generation and detection of shear waves in solids have been developed. The transducers consist of arrays of ceramic bimorph bender elements arranged to propagate shear waves from the ends of the elements. The transducers have been used to measure shear-wave speed and attenuation in laboratory mixed kaolinite clays and carbonate clays having shear moduli as low as 1.7×102 dyn/cm2. Shear-wave speeds of 2 m/sec with attenuation of 496 dB/m have been measured over path lengths of 5 to 10 cm.
Evaluation of transducer window materials
Authors: Mikeska E. Eugene , Behrens John A.
Published: October 2005

Acoustic measurements of insertion loss and echo reduction at normal incidence were made for several materials for evaluation of their use as underwater sound transducer windows in the frequency range of 50–500 kHz. Materials tested included the commercial polyurethane products such as PR-1527, CPC-19, Scotchcast 221, Scotchcast 8, and some of these materials with talc added during curing to vary the density. Values of sound velocity are derived from the echo reduction data and allow determination of ρc values for each material. A computer model of the echo variation with frequency accurately matches the measured echo reduction plots.
Analytical model of an explosive source
Authors: Lauer R. B. , Herstein P. D. , Maples L. C.
Published: October 2005

An analytical expression, consisting of a series of transcendental functions, has been developed to simulate the waveform of an underwater explosive source. From this model the source spectrum may be calculated as function of charge weight and detonation depth. Energy flux density spectrum levels for 1.8-lb TNT charges detonated at 60, 300, and 800 ft have been computed for ANSI 1/3-octave bands in the range 10–1780 Hz. Comparison with results of a study by Gaspin and Shuler utilizing waveforms constructed from actual measurements of explosive parameters shows a mean difference of 0.6 dB and a standard deviation of 0.8 dB, above the bubble frequency. Agreement below this frequency is less satisfactory. The spectrum characteristics below the bubble frequency are not well understood but parameters associated with the first bubble pulse are shown to be important in this region. Preliminary studies of the sensitivity of the spectrum to changes in value of waveform parameters indicate the accuracies to which the magnitudes of various parameters must be known. Farther studies show the effects of small variations in detonation depth.
Effect of phase on the timbre and detection of timbre of complex tones
Authors: Nagai Toshiaki , Mori Shinsaku , Ono Hiroshi , Saito Shigeji
Published: October 2005

It has been assumed that the human auditory organ can detect only the spectra of complex tones, but recently it would appear that the ear can detect not only these spectra but also the difference of the phase relation among harmonics. In such a case, however, the condition of detecting has not yet been discussed thoroughly. We have made many psychological experiments on complex tones, in which the power spectrum has remained constant but the phase relation of the harmonics has been varied. As a result, we recognized the following: (1) When we changed the phase of one harmonic of the complex tones, most of the observers could detect the difference of timbre when the phase difference was nearly π. (2) When the complex tones are made up of only fundamental and the second harmonic, as the fundamental frequency increased, the effect of the difference of phase on timbre diminished. Therefore, we hypothesized the following law between timbre and phase. If an effect of the phase exists between the harmonics of the complex tones and if it occurs in nature, we can detect the differences of timbre. At present, we are conducting experiments to support this hypothesis.
Subjective tones: Growth of 2f1+fh and fh+f1 for independently varied primary amplitudes
Authors: Erdreich J.
Published: October 2005

Two nonlinear amplitude distortion mechanisms have recently been proposed as explanations of the generation of aural combination tones. One, a polynomial power series, predicts combination tones which grow at an accelerated rate in comparison with the increased stimulus amplitudes. The second, an essential nonlinearity, predicts distortion product relative levels independent of stimulus amplitude. In a past study [J. Erdreich and T.D. Clack, J. Acoust. Soc. Am. 55, S7–S8 (1974)], it was shown that only when a combination tone becomes audible and presumably subject to modification by perceptual processes does it grow at nonaccelerated rates. The current study examines the growth of the cubic summation tone 2f1+fh and the quadratic sum tone fh+f1(fh/f1=1.2, f1=1 kHz) as the level of each primary is varied independently. It is found that the accelerated distortion product growth rate conforms with the predictions of the power-series nonlinearity hypothesis. [Supported in part by grant from Sigma Xi.]
Nonspectral pitch
Authors: Viemeister Neal F. , Burns Edward M.
Published: October 2005

The spectrum of amplitude-modulated wide-band noise is invariant with changes in modulation frequency, and consequently such waveforms cannot convey melodic information by spectral changes. The results of several experiments indicate, however, that sinusoidally amplitude-modulated wide-band noise does have pitchlike properties. Simple melodies can be identified when the “notes” are different modulation frequencies. More importantly, musically trained observers can immediately recognize melodic musical intervals composed of such waveforms. The pitchlike properties of modulated noise are maintained when the modulated noise is bandpass filtered and when an unmodulated band-reject masker is added to the bandpass noise. Presumably the perception of pitch elicited by modulated noise is based upon temporal information in the envelope of the waveform. This “temporal pitch” is less salient than the pitch elicited by pure tones. Also, temporal pitch can be elicited only over a restricted range of modulation frequencies. The upper limit (approximately 300–400 Hz) appears to reflect the inability of the auditory system to follow rapid temporal changes. [Supported by NIH, and by the Graduate School of the University of Minnesota.]
Context-free judgment of tonal stimuli by musicians
Authors: Siegel Jane A. , Siegel W.
Published: October 2005

While speech sounds may be identified on an absolute basis, it is thought that tonal stimuli are judged on a contextual basis, in relation to immediately preceeding stimuli. Evidence is presented here that musicians with relative pitch are able to judge tonal intervals on an absolute basis, and that musicians with absolute pitch can judge single-tone frequencies without reference to context. In Experiment I, four subjects with relative pitch and four controls made magnitude estimates of 21 intervals spaced in equal-log steps over a range of five semitones. After six blocks of trials, the stimulus range was shifted suddenly without warning. The postshift set consisted of 11 intervals from the preshift condition, plus ten larger intervals. The controls showed judgmental contrast, which built up monotonically over the six postshift trial blocks, while the relative pitch group was virtually uninfluenced by the shift in context. Similar results were obtained in Experiment II, in which six possessors of absolute pitch and six controls judged single-tone frequencies.
Pitch shift of two tone bursts in close temporal proximity
Authors: Minick L. S. , Elmasian R. , Galambos R.
Published: October 2005

The perception of a brief target tone (S1) may be altered by a preceding tone burst (Tc). The present study shows this perceptual interaction in the frequency domain. When the target tone burst is presented alone, subjects adjust the frequency of a variable tone to match target pitch so that the two stimuli are approximately equal in frequency. When Tc precedes the target by a short interval (150 msec), however, the pitch of the target is altered in the direction of Tc's frequency. The magnitude of this pitch shift increases as the interstimulus interval is decreased below 500 msec. The results from these experiments are compared to similar two-tone interactions in the loudness domain [e.g., Elmasian and Galambos, J. Acoust. Soc. Am. 58, 229–234 (1975)].
Identification of specific random auditory waveforms
Authors: Pollack Irwin
Published: October 2005

Can listeners identify specific high-frequency random waveforms, randomly selected from large pools of possible waveforms? If so, can such performance be enhanced by restricting the size of the pool? Yes, listeners can identify specific random waveforms. No, any limitation upon the pool results in either the same or in poorer performance. Since all random selections from the same pool have nearly identical long-term spectral characteristics, listeners must perform a short-term, or running, spectral analysis upon the signals.
Low-frequency absorption coefficient in the Canadian Basin
Authors: Diachok O. I.
Published: October 2005

A model of under-ice reflectivity (Diachok, Proc. 8th Int. Congr., Acoust., 1974) predicts that the effect of ice on attenuation is frequency independent at high frequencies. As predicted, the attenuation coefficient extracted from transmission loss measurements in the Canadian Basin is frequency independent between 200 and 800 Hz. At higher frequencies, however, other effects are apparent. At 1 kHz, a frequency-independent attenuation coefficient in excess of the attenuation due to under-ice reflection loss is estimated to be 0.02±0.01 dB/km. This result is slightly lower than Mellen's and Lovett's estimate of the absorption coefficient in the North Pacific ocean, which at 1 kHz is approximately equal to 0.03 dB/km, and is much lower than Thorp's estimate of the absorption coefficient in the North Atlantic Ocean, which at 1 kHz is approximately equal to 0.06 dB/km. Simmons, Fisher, and Levinson attribute the observed attenuation in this frequency range to a relaxation of boric acid, and suggest the possibility of a dependence on concentration. Hence it may be noteworthy that the near-surface salinity at this particular measurement site, being between 27 and 37 ‰, is among the lowest in the world ocean.
Effect of sea-surface roughness on sound transmission in the ocean mixed layer
Authors: Hall Marshall
Published: October 2005

A series of 20 experiments on sound propagation in the mixed layer has been conducted in deep ocean areas around Australia. The results of the first eight experiments were reported at the 89th Meeting of the Acoustical Society [J. Acoust. Soc. Am. 57, S63(A) (1975)]. The results of the remaining 12 experiments are presented in this paper. This second set of experiments differs from the first set in that acoustic backscattering experiments were also conducted (in order that the scattering strength of the sea surface could be determined), and the sea surface roughness was monitored with a wave-rider buoy (in addition to visual estimates). These experiments have encompassed a wide range of oceanographic conditions: the mixed-layer thickness ranged from 20 m in one experiment, to 90 m in another; the swell height varied between 0.0 and 1.5 m; and the wind speed from 0.5 to 18 knots. The sound sources were small, shallow explosives, and the results have been analysed at frequencies of 4, 8, and 16 kHz. Results for propagation loss for receivers both in and below the mixed layer have been obtained, for horizontal ranges from 0.5 to 6 km. These results are compared with the normal-mode curves applicable to each experiment, in order to show directly the effect of any roughness in the sea surface. In addition, comparisons are made between the experimental results and curves obtained from a first-order scattering theory based on ray acoustics.
Susceptibility to auditory fatigue: Comparison of changes in cochlear nerve potentials in guinea pig and chinchilla
Authors: Mitchell Curt
Published: October 2005

The N1 potential of the cochlear nerve was recorded in order to study fatigue in the chinchilla and guinea pig. The intensity of the exposure stimulus was referenced to the maximum cochlear potential output. The results indicate that the chinchilla is more susceptible to fatigue than the guinea pig. However, they suffer nearly the same loss when one equates for cochlear potential output. This suggests that impedance differences in their ears account for the susceptibility difference.
Measurement of the acoustic impedance of an internal combustion engine
Authors: Galaitsis A. G. , Bender E. K.
Published: October 2005

The specific acoustic impedance ζ of an internal combustion engine has been studied experimentally to promote the computer-aided muffler design to a higher level of sophistication. Measurements were performed with a specially prepared impedance tube facility capable of accommodating the hot and moving exhaust gases. At low engine speeds (RPM) the ζ trace on the complex ζ plane follows an irregular path that cannot be readily modeled in terms of simpler acoustic components. At higher RPM, however, the trace becomes a spiral, centered at and slowly converging towards ζ = 1, indicating a resemblance to an open-ended pipe segment. The measured ζ has been used in designing a muffler for this internal combustion engine with favorable results.
Experiments in electrostimulation as a therapy for sensori-neural hearing loss
Authors: Prout J. H. , Cook W. , Erickson D.
Published: October 2005

Since 1969, experiments have been conducted by various laboratories to evaluate an electrostimulation device offered commercially as a therapy for sensorineural hearing loss. The device manufactured by Intelectron Corporation passes an amplitude modulated high-frequency carrier current through a subject's head by means of an array of four electrodes worn in the manner of a set of headphones. The therapy requires electrostimulation for approximately one hour per day, five days per week for a period of six weeks to produce an improvement in speech discrimination. Groups receiving active electrostimulation have been compared with control groups receiving simulated treatment. Results have been quite variable among the laboratories and have led to considerable controversy as to the effectiveness of the therapy. The success of the therapy achieved by the Pennsylvania State University and the UCLA Medical Center has allowed these experiments to continue and has shed much light on the procedures required to produce the greatest improvements. A recent experiment at Penn State involving tests of evoked responses and middle ear reflex measured before and after therapy produced some unexpected results. The improvements obtained in speech discrimination in this most recent experiment were so marginal that an investigation was launched into the effects of the placebo switch box on the therapy current. These findings to be presented help explain the success or failure of previous experiments and provide information needed to improve the efficiency of the therapy.
Influence of F pattern on the perception of duration
Authors: Lehiste Ilse
Published: October 2005

Thirty listeners were presented with pairs of stimuli of equal duration, but differing in F0, and were asked to decide which of the two stimuli was longer. The stimuli consisted of the vowel /a/ synthesized on a Rockland synthesizer. There were three durations: 270, 300, and 330 msec. In one set, one of the members of the pair had a monotone F0 at 120 Hz; the other member had a rising-falling F0 curve whose peak ranged in 12 semitone steps from 127 to 240 Hz. In the other set, the monotone frequency was 240 Hz; the changing member of the pair had a falling-rising F0 curve whose lowest value ranged from 227 to 120 Hz. Level patterns at 120 Hz were also included at each duration. In the case of level patterns, 68.7% of the listeners judged the first member of the pair to be longer. When the pitch inflection was on the first member of the pair, 71.1% of the listeners judged it to be longer. When the second member of the pair had changing pitch, the listeners' judgment that the second member was longer rose from 31.3% for the level pattern to 60.5%.