bluuebunny/crossref_metadata_2025 huggingface dataset:
Vowel boundaries and waveform patterns
Authors: Scott Brian L.
Published: October 2005

Relations between changes in the temporal fine-structure of synthetic vowel waveforms and perceptual boundaries are examined. Small changes in fundamental frequency (FO) are shown to affect temporal fine-structure and perceptual boundaries in a correlated manner. Experiments show that ambiguous vowel sounds lying on the continuum /i/ and /ɪ/ can be shifted to either category by manipulating FO and that the shifts can be predicted from the resulting changes in waveform. In an additional study, a series of pseudovowels identical in FO and formant center-frequency values but differing in temporal fine-structure are shown to bear perceptual relationships to one another similar to a normal /i/-/æ/ vowel series. The results indicate that temporal analysis of the first formant of vowel sounds can aid in delineating vowel boundaries. [Supported by NIH grant NS 03856 to CID.]
Selective adaptation effects on end-point stimuli
Authors: Sawusch J. R.
Published: October 2005

A series of voiced CV syllables which varied along the feature of place was used in a selective adaptation paradigm. The end-point stimuli from the test series and their voiceless counterparts were used as adaptors. Subjects used a six-point rating scale to respond to the stimuli, instead of the usual two category identification. The average rating for end-point stimuli from the same category as the adaptor, as well as boundary stimuli, shifted as a function of adaptation. In all cases, the average rating response shifted toward that of the unadapted category. The average rating for end-point stimuli in the opposite category from the adaptor remained relatively unchanged. Results indicate that the entire category of the adapting stimulus changes as a result of selective adaptation and that the effect is not confined to stimuli near the phonetic boundary. These results agree with end-point shifts found recently using a dichotic listening task [J.L. Miller, Percep. Psychophys. (in press)]. Results are interpreted in terms of recent models of the adaptation process. [Research supported by NINCDS Grant NS-12179.]
Production and utilization of junctural acoustic cues under different speaking conditions
Authors: Harris M. S.
Published: October 2005

At a previous meeting we reported perceptual results concerning so-called internal open juncture phrases in three situations: spoken in isolation, embedded in proper sentences, and embedded in nonsense sentence frames in which the other member of the minimal pair made sense. The rate of correct responses decreased in the above order. In nonsense sentences, in particular, the rate of correct responses was quite low. Acoustic analysis of the production of these minimal pair phrases in the different environments is currently under way. Initial inspection of the duration data indicates features in the isolated phrases that are in proper sentences. It appears, because the phrases in inappropriate sentence frames were also emphasized, that the speaker took extra care in articulating these phrases. This is particularly interesting because the listeners did not detect or choose to use the additional acoustic cues provided by the feature emphasis.
Formant structure of Bengali vowels uttered in isolation
Authors: Kader Pramanik M. A. , Kido Ken'iti
Published: October 2005

The general structure of formant frequencies of eight Bengali vowels /ɔ/, /a/, /i/, /ii/, /uu/, /e/, and /o/ is investigated for the first time. The formant frequencies of the Bengali vowels uttered by well-educated Bengalee natives were extracted using the analysis-by-synthesis method [Bell and Fujisaki, J. Acoust. Soc. Am. 33, 152 (1970)]. In the text, the first vs second and first vs third formant frequencies distributions are discussed and compared with those of the American English and of the Japanese language. It has been found that the values of the third formant frequencies of all vowels are roughly similar and unlike the American English and the Japanese the F1−F2 pattern of /e/ and /i/ are very close upon the plane and those of /ɔ/, /a/, /o/, and /u/ are forming another group upon the same plane. The vowel /ii/ possessing formants similar to those of /i/ and /uu/ is possessing formants similar to /u/.
Traffic generated L10 levels by peak averaging
Authors: Long Marshall
Published: October 2005

Microsampling techniques for monitoring traffic noise can require large sample sizes for reasonable accuracy. Often errors are larger than expected due to the observer's inability to mentally average a fluctuating level with the necessary skill. A method is proposed whereby L10 levels may be determined by arithmetically averaging the peak levels made by passing vehicles and by applying a correcting term: Lmax¯ − L10 = 10log(1 + 0.0245sinhx2), where x = πd/s, d is the minimum distance to the vehicle, and s the average vehicle spacing.
Technique for measuring the sound of a moving source
Authors: Chung J. Y. , Wilken I. D.
Published: October 2005

A measurement and analysis technique has been developed to determine the narrow-band spectra and the radiation patterns of sound emitted by a moving source. The sound is measured by a semicircular array of stationary microphones as the source passes by the array, and is recorded on a multichannel tape recorder. The sound pressure signals are digitized and the analysis of the data is completed on a digital computer. The analysis procedures make corrections for the effects associated with a moving sound source, such as the nonstationarity of the signal due to the time-dependent transmission path, the Doppler frequency shifts associated with each microphone, and the determination of accurate narrow-band spectra from a short segment of a rapidly varying signal. A relationship between the finite Fourier transform and the Doppler effect has been derived and serves as a basis for the Doppler correction procedure. The output from the analysis consists of the spectra of the sound emitted in the direction of each microphone and the radiation patterns for given frequency ranges or for weighted overall sound pressure levels. The technique was developed as part of a study of the mechanisms of tire noise generation using a single-wheel trailer. Results from the tire noise analyses are used as examples.
Sound attenuation of building size barriers
Authors: Russell G. A. , Ivey E. S.
Published: October 2005

A nomograph for the prediction of excess sound attenuation over barriers of building size is presented. The nomograph is based on the results of acoustic scale model experiments carried out using techniques and equipment developed by Lyon [Lyon and Cann, “Acoustical Modeling in Urban Environments,” Inter-Noise '74 Proc. 457 (1974)]. A scale factor of 64:1 was employed with barrier width to height ratios ranging from 0.0 to 5.0. Measurements were made in the free field and with the barrier on both reflective and absorptive surfaces. Results indicate a dependence on type of ground surface, with the excess attenuation increasing more for a given increase in building width on the reflective surface than on the absorptive surface. Attenuation due to the diffraction of sound around the edge of a building is also briefly discussed.
Superdirective spherical radiator
Authors: Butler John L. , Ehrlich Stanley L.
Published: October 2005

The condition for the maximum directivity from a spherical radiator is presented and it is shown that this directivity Index is 20 logN, where N is the number of consecutive modes excited. In this case, the relationship among the expansion coefficients is particularly simple and a closed-form expression for the beam pattern function results. Using this method, a high directivity may be obtained no matter how small the sphere is, provided that the prescribed velocity distribution is maintained. Examples of the resulting beam patterns are given.
Supergain in flatland
Authors: Kooij Theo , Cox Henry
Published: October 2005

The potential of superdirective receiving arrays in two-dimensional fields is investigated and contrasted to well-known results for three-dimensional fields. It is shown, for example, that the theoretical limiting gain of a short endfire array of M elements in a two-dimensional isotropic field is 2M-1 compared to the well-known limit of M2 for the three-dimensional isotropic field. Calculations of gain and sensitivity are presented for arrays of finite length. Superdirective results with a constraint on sensitivity to errors are also presented.
Superdirective end-fire array
Authors: Hughes W. J.
Published: October 2005

A ten-element end-fire line array was designed for use as a superdirective array. A superdirective array can produce a sharper beamwidth by accepting a reduced sensitivity on the main beam. This is potentially very advantageous since a reduction of only a few decibels in sensitivity can reduce the beamwidth by as much as one-third. A design curve is presented for the superdirective ten-element array which relates the required phase shift between the elements to beamwidth and relative peak sensitivity as a function of frequency and element wavelength spacing. Also presented on these curves is the change in beamwidth with frequency when the requisite phase shift is produced by an ideal delay line. Directivity patterns are given which exhibit a −3 dB beamwidth reduction from 70° to 41° with a sensitivity loss of 7 dB. The experimental results agree reasonably well with theoretical predictions. [Work supported by NAVSEA.]
Physical correlates to the spatial impression in concert halls through binaural simulation
Authors: Conant David A.
Published: October 2005

A calibrated binaural manikin and tape record/playback technique is described from which meaningful subjective and objective characteristics of the acoustical “atmosphere” of locations in spaces are extracted. Analysis of the source-path(s)—receiver(s) transfer functions in space, frequency, and time domains together with psychoacoustical paired comparisons using headphones and properly calibrated, single-source anechoic music played in several auditoria showed the following: (1) “Apparent source width” (ASW) can vary significantly throughout a space and, among other things, is a function of listening level and the running, short-time, cross-correlation coefficient between the ears for frequencies below about 2 kHz. (2) In general, when the sound source is located on the axis of symmetry of a room, listeners are likely to feel more surrounded by sound (large ASW) when they are seated some distance from that axis (t=2.90, df=49, significant at the 99.5% confidence level).
Design parameters for acoustical treatments in a subway station renovation
Authors: Rosenberg Carl J. , Powers Neville A. , Lieb Allen M.
Published: October 2005

Acoustical treatments have been incorporated into the design of renovations in the Essex Street MBTA Station in Boston. Criteria were developed relating to noise reduction from train noise on the platform and sound isolation between northbound and southbound sides of the station. This paper discusses the limitations on acoustical treatments imposed by the functional and structural restraints of the station, including the availability of surfaces to be treated, safety access requirements, maintenance and durability restrictions, and architectural goals relating to aesthetics, lighting, and textures. The presentation focuses on the manner in which the acoustical consultant and architect responded to each other's goals and the way that conflicts were resolved. Measurements were made of existing acoustical parameters. The renovations are presently under construction.
Recent experience with spaces for musical performance and rehearsal
Authors: Martin Daniel W.
Published: October 2005

Posters, drawings, and photos will show acoustical design details of the auditorium organ installation and of the orchestra rehearsal studio at Cincinnati Music Hall; of the Corbett Auditorium, Watson Recital Hall, and associated rehearsal studios of the University of Cincinnati College Conservatory of Music; and of the recital, rehearsal, and practice studios of the Miami (Ohio) University Center for the Performing Arts.
History of American acoustics—Introductory comments
Authors: Cook Richard K.
Published: October 2005

The history of acoustics has been illuminated by the efforts in recent years of R. Bruce Lindsay, and so this Bicentennial Session is being held in his honor. In addition, certain numerological factors spurred our efforts in this Bicentennial Year 1976. It was just one hundred years ago that A. G. Bell's invention—the first practical telephone—was exhibited at the 1876 Centennial Exposition in Philadelphia. A year later, in 1877, the first edition of Rayleigh's Theory of Sound appeared. The conjunction of these two events eventually had a powerful influence on the development of acoustics. The invited speakers will, in the papers which follow, endeavor to describe all of the significant advances made by Americans to technical acoustics. Apparently it all began with Joseph Henry's efforts to solve a problem in auditorium acoustics. At the brink of World War II, acoustics was invaded by a host of scientists and engineers. During the period 1941–45, and in the post war years, frontiers were breached in almost every direction at such a rate that description of the advances made cannot be done here. And so most of our speakers will bring their histories up only to about the year 1940.
Electroacoustics covering the period up to 1940
Authors: Hilliard John K.
Published: October 2005

The concept of acoustical and motional impedance had been conceived and applied to the design of transducers several years before the acoustical society was founded in 1928. It seems appropriate at this time to review some of the individuals and their developments which contributed to the advancement of transducers by application of the impedance concept. A. E. Kennelly, G. W. Pierce, and A. G. Webster introduced the terms “motional impedance” and “acoustical impedance.” The word transducer is now a generic term denoting conversion. The work of Wente, Rice, Kellogg, Maxfield, Harrison, Thuras, and others preceding 1930 will be outlined as well as how they used the impedance concept to predict transducer performance providing the basic concepts which others were to use later to extend frequency range and efficiency. In the period between 1930 and 1940 the application of transducer design was expanded to many fields of electroacoustics. Wente, Thuras, Olson, Hilliard, and Klipsch contributed to improvements in sound reproduction for audience and home reproduction.
Acoustic measurements and instrumentation
Authors: Miller Harry B.
Published: October 2005

A few selected topics will be discussed. Each had a major influence in setting a new trend. The discussion will include: the significance of Wente's condenser microphone in freeing acoustic measurements from the constraints of contemporary microphones; the effect of Maxfield and Harrison's paper on the analysis and synthesis of acoustic devices; the evolution of the reciprocity principle into a measurement tool.
History of physical acoustics in North America up to World War II
Authors: Blackstock David T.
Published: October 2005

The history of physical acoustics in the United States and Canada is traced up to about 1942. Among the areas covered are finite-amplitude sound, atmospheric propagation, including ground reflection; absorption and dispersion of sound in both gases and liquids; interaction of sound and light; and ultrasonics in general. The developments in electronics and electroacoustics in the 'teens and 20's gave great impetus to experimental physical acoustics in the 20's and 30's. But important contributions were made in the preelectronics era too, for example, the first-ever measurement of sound absorption in open air, made by A. W. Duff [Phys. Rev. 6, 129–139 (1898)]. [Supported by ONR and AFOSR].
Review of undersea acoustics: 1900–1950
Authors: Lasky Marvin
Published: October 2005

For much of the first four decades of the twentieth century (with the exception of an impulse effort during World War I) undersea acoustics had limited financial support and a small number of practitioners. During 1940–1950 this situation changed. A massive effort funded by the U. S. Navy enabled a large multidisciplined group of civilian scientists to transform a previously relatively simple pragmatic “art” into an increasingly complex emerging science.
A preliminary investigation of speaker photograph identification
Authors: Lass Norman J. , Harvey Lisa A.
Published: October 2005

The purpose of this investigation was to determine if listeners were capable of speaker photograph identification from recorded samples of speakers' voices. A standard prose passage was recorded by 30 speakers, 15 females and 15 males. A master tape containing the randomly arranged recorded readings was played to a group of 30 subjects. The subjects were shown photographic slides of two persons on a screen simultaneously and heard a recording of a single speaker reading a standard prose passage. Their task was to determine to which of the two photographs did the speaker's voice belong. All subjects participated in two experimental sessions. In one session they were shown full-length photographic slides and in another session portrait slides were employed. Results indicate that (1) for both order groups and both kinds of photographs, subjects were capable, with better than chance-guessing accuracy, of correctly identifying the photographs of speakers; (2) subjects exhibited slightly greater accuracy in speaker photograph identification under the full-length condition; and (3) subjects were more accurate in their identification of photographs of female speakers than they were for male speakers.
Clinical estimation of fundamental frequency: the 3M Plastiform Magnetic Tape Viewer
Authors: Kelly D. H. , Sansone F. E.
Published: October 2005

The purpose of this study was to determine the accuracy and reliability of the 3M Viewer in measuring fundamental vocal frequency and to suggest a method of incorporating the 3M Viewer into the clinical measurement of pitch. A total of forty normal speaking persons served as subjects. Recorded sustained terminal vowel segments were obtained from each subject following procedures outlined by Fairbanks and Wilson. The terminal vowel segments were then analyzed utilizing two electronic systems for extracting fundamental frequency (electronic band-pass filters and digital frequency counter; Kay Elemetrics Sonograph), and 3M Viewer. Measurements made with the 3M Viewer by three observers were submitted to a linear regression analysis. The fundamental vocal frequency estimates from each of the three methods of fundamental frequency determination were submitted to an analysis of variance. Results suggest that the three estimates with the 3M Viewer are not significantly different from one another and that the 3M Viewer method of estimating fundamental vocal frequency is at least as accurate as the other two methods employed in this study.
Identification of synthetic diphthongs with variable transition duration
Authors: Bond Z. S.
Published: October 2005

Traditionally, diphthongs have been described as consisting of an initial steady state portion, a transition, and a relatively short final steady state portion. Gay [“A Perceptual Study of American English Diphthongs,” Lang. and Speech 13, 65–88 (1970)] found that the presence of a transition without steady state portions is sufficient for the identification of synthetic diphthongs. This study investigated the contribution of transitions of variable duration, in the presence of steady state portions, to diphthong identification. The three American English diphthongs /ai/, /au/, and /oi/ were synthesized, employing fixed durations for the steady state portions and varying the duration of the transition from 0 (no transition) to approximately 150 msec. Two-vowel sequences, identical to the steady state portions of the diphthongs and separated by pauses of varying durations, were also synthesized. Comparable sets of synthetic diphthongs and two-vowel sequences, synthesized at different fundamental frequencies, were presented to different groups of subjects; the subjects were required to identify each stimulus item as one of the three diphthongs or one of the three possible two-vowel sequences. When the transitions were short or absent, subjects were consistent in identifying the stimuli as diphthongs. For some stimulus items, even relatively long pauses separating two steady state vowel segments were ineffective in shifting the identification to a vowel sequence.
Dependence of loudness growth on skirts of excitation patterns
Authors: Hellman Rhona
Published: October 2005

Loudness growth spanning a SL range of 50 dB was measured for a 100-Hz tone in a noise band 200 to 9600 Hz wide. The noise was varied in intensity along with the tone so that during a given listening session the signal-to-noise ratio remained constant at either 0 or −10 dB. Listeners judged the loudness of the tone by loudness matching, magnitude estimation, and magnitude production. The noise markedly decreased the rate of loudness growth of the tone but not the range over which loudness grows. The overall decrease in steepness of the 100-Hz loudness function was found to be greater than that previously reported at higher frequencies. It is suggested that, in contrast to similar measurements at higher frequencies, the excitation spread of a 100-Hz tone to both low and high frequencies has been experimentally contained. While it appears that stimulation produced by the entire excitation pattern is necessary to obtain the expected growth rate of loudness, the loudness growth range may not depend on excitation produced by low- and high-frequency skirts. Supportive data for this hypothesis are given by measures of intensity discrimination at 100 Hz. [Work supported by NIH.]
How well can audible warning devices of emergency vehicles be localized by the driver of an automobile?
Authors: Potter Richard C. , Pei Hsien-sheng
Published: October 2005

A series of direction determination experiments has been performed to evaluate the extent to which automobile drivers can locate audible warning devices of emergency vehicles. Blindfolded subjects were required to indicate the perceived position of a siren, first in an open space and, secondly, while seated in an idling automobile with the windows both open and closed. For the open-air control case, the direction of the siren was correctly indicated to be in the appropriate 45° sector for 91% of the test presentations. With the subject seated in the automobiles, the identification of the correct location fell to 37.6% with the passenger window open and 26% with the windows closed. Based on an analysis of the results and the magnitude of the errors, it is concluded that aural localization for the directional identification of emergency vehicles is not practicable. [Work supported by the Society of Automotive Engineers, Inc.]
A hearing aid malfunction detection unit (HAMDU)
Authors: Roeser R. J. , Gerken G. M. , Glorig A.
Published: October 2005

Two independent surveys were conducted to assess the performance of hearing aids worn by 290 children, fourteen years of age and less. Results from both surveys showed that between 30% and 35% of the aids evaluated were not functioning or were functioning improperly. A need exists, therefore, for some method of assessing hearing aid function in school age children. A system is described, the hearing aid malfunction detection unit (HAMDU), that electrically checks for proper operation of several aspects of hearing aid function. HAMDU is a miniature, add-on device which performs a check every half hour of hearing aid operation, and which indicates malfunction by means of a highly visible, electrically tripped, indicator. Functions checked include: battery voltage, gain, distortion and noise, and integrity of the receiver cord. In addition, the indicator will be tripped if the hearing aid is turned off. HAMDU is small, low in cost, and can be adapted to most body aids. [Supported by the NSA.]
Short-term adaptation in single auditory-nerve fibers-some poststimulatory effects
Authors: Smith R. L.
Published: October 2005

Adaptation was produced by CF stimuli with durations ranging from 10 to 300 msec and intensities within 60 dB above a unit's threshold. The exposure caused a decrement in the response to a CF test tone applied after the termination of the adapting stimulus. In general, the poststimulatory decrement seemed to depend on the per-stimulatory response to the adapting tone and not directly on the parameters of the adapting stimulus. For example, the decrement followed a saturating function of adapting sound intensity and was approximately proportional to the per-stimulatory firing rate. At sufficiently high test intensities, the decrement was constant and independent of test intensity, and the saturation rate produced by the test tone was reduced. These poststimulatory results are qualitatively consistent with a model previously developed to describe some per-stimulatory effects of short-term adaptation [R. L. Smith and J. J. Zwislocki, Biol. Cybern. 17, 169–182 (1975)]. In both situations, a peripheral saturation appears to precede adaptation and limit the effects of high sound intensities.
Early evoked responses in patients with acoustic neuroma
Authors: Daly D. M. , Roeser Ross , Daly D. D.
Published: October 2005

Early components of the auditory evoked response, arising in the brainstem, can be illicited by clicks or (coherent) tone bursts. Daly et al. [EEG Clin. Neurophysiol. (in press)] have shown that the latter, frequency-following response (FFR) represents the iterative activation of brainstem generators by succeeding cycles of the stimulus tone. In patients with acoustic neuromas, stimuli presented at less than some “critical off time” produce threshold instability. In four patients with acoustic neuroma, FFR at 500 Hz was markedly distorted or absent despite normal threshold sensitivity for the stimulus tone. At higher intensities, a response similar to the cochlear microphonic appeared. Such FFR's distinguish patients with angle tumors from patients with ochlear pathology, sensorineural loss, and intrinsic brainstem lesions. These studies offer a new methodology for evaluating the functional integrity of the VIII nerve and for early detection of acoustic neuromas. [Supported by N.I.N.C.D.S./NS02098.]
Evoked potential activity in the auditory thalamus of the bullfrog—Responses related to call detection
Authors: Mudry K. M. , Capranica R. R.
Published: October 2005

Evoked potential activity was studied in the auditory thalamus of the bullfrog, Rana catesbeiana. The maximum evoked potential was obtained when a low-frequency tone (200 Hz), a mid-frequency tone (800 Hz), and a high-frequency tone (1400 Hz) were presented simultaneously. Furthermore the magnitude of the evoked potential to the three simultaneous tones was greater than the sum of the magnitudes of the evoked potential to each tone presented separately. The best response was obtained when the three tones were of approximately equal amplitude, and a good response could be maintained over a 50-dB intensity range. At higher intensity levels, when the amplitude of the mid-frequency tone was increased relative to the other tones, pronounced suppression of the evoked potential occurred. The response was also very dependent on the rise time of the tone burst, with a 100-msec rise time giving the best response. The parameters of the auditory stimulus necessary for an optimal evoked response will be compared with the signal characteristics of the calls in the bullfrog's vocal repertoire. [Supported by NIH Grant NS-09244.]
Vocal communication and the development of hearing in the pallid bat, Antrozous pallidus
Authors: Brown Patricia E.
Published: October 2005

Adult pallid bats (Antrozous pallidus) communicate via four main types of sound emissions: directives, squabble notes, irritation buzzes, and orientation pulses. The isolation call is the only sound emitted by newborn bats. It changes in quality as the bat matures, until by the twentieth day it resembles the adult directive. Orientation pulses are not produced until 7–9 days of age. Mother bats nurse only their own young and recognize their infants on the basis of auditory and olfactory cues. A vocal signature is present in the isolation call and appears to manifest itself through the temporal patterning of frequencies. Adult pallid bats possess auditory capabilities similar to those of other echolocating Vespertilionids. Newborn bats show no behavioral or neurophysiological responses to auditory stimuli. Evoked responses were first recorded from the posterior colliculus in a six-day-old bat in response to loud, low-frequency sounds. Absolute sensitivity and frequency range increase rapidly in the maturing bat. By 24 days, the audiogram resembles that of the adult. Except for the first week after birth, the infant bat's vocalizations contain only frequencies which it can hear.
Some aspects of low-frequency neural and cochlear microphonic tuning curves
Authors: Schmiedt R. A. , Zwislocki J. J.
Published: October 2005

Tuning curves of single auditory nerve fibers of the Mongolian gerbil (Meriones unguiculatus) have been compared to cochlear microphonic (CM) tuning curves corrected for the electrical filtering effect of the cochlea. Results indicate that CM tuning in the second and third turns is similar to the tuning of fibers whose characteristic frequencies (CF's) correspond to the CM best frequencies (2.5 and 0.5 kHz). Accordingly, little sharpening seems to take place for fibers with low CF's. The CM tuning curve recorded from the most apical position is sharper than expected for frequencies below the best frequency. The low-frequency sharpening probably arises from the shunting effect of the helicotrema. Modeling results have confirmed that the mechanical impedance of the helicotrema can exert an appreciable effect on basilar-membrane tuning in the apical regions.
Neural vs mechanical tuning curves in the CF-FM bats, Pteronotus parnellii rubiginosus
Authors: Suga N. , Jen P. H.-S.
Published: October 2005

In the mustache bat (P. p. r.), the CM recorded from the round window is sharply tuned at 61 kHz and shows a prominent transient response to a tone burst of about 61 kHz, i.e., it increases exponentially at the onset of the stimulus and decreases at its cessation. In terms of the time constant (1.1 msec) and the resonance frequency (61.1 ± 0.43 kHz) of this transient response, the Q value of this system is 205 ± 56. Peripheral neurons sensitive to 61 kHz have a very sharp excitatory area (or tuning curve). The Q value of a tuning curve drastically increases with the rise in best frequency up to 61 kHz and decreases beyond 61 kHz. The average Q value of single neurons with best frequencies between 60.76 and 61.75 kHz is 209 ± 91. If the assumption that the CM is directly related to the mechanical motion of the basilar membrane is correct, the very sharp tuning curves of single neurons at about 61 kHz could be simply due to the mechanical tuning of the basilar membrane. [Work supported by NSF.]
Difference between CM and N1 tuning curves in the CF-FM bats, Pteronotus parnellii rubiginosus
Authors: Jen P. H.-S. , Suga N.
Published: October 2005

In the mustache bat (P. p. r.), cochlear microphonic (CM) is sharply tuned at 61 kHz while N1 is tuned at 64 kHz. The amplitude of the CM evoked by a 61-kHz signal increased and decreased exponentially at the onset and cessation of the stimulus, respectively. Its rise time, which affects the threshold of the N1, varied as a function of the stimulus frequency even for a constant rise time stimulus. The longer the CM rise time, the higher the N1 threshold is. To eliminate the effect of the CM rise time on the N1 tuning curve, the stimulus rise time was adjusted on the basis of single unit tuning curves and the CM rise time was kept constant. Then the N1 tuning curve was measured and was found tuned at 61 kHz instead of 64 kHz. This indicates the difference in best frequency between the CM and N1 is simply due to the properties of a sharply tuned resonator and N1, but not due to a mechanism comparable to lateral inhibition. [Work supported by NSF.]
Some type problems of fluid-structure interaction
Authors: Scanlan R. H.
Published: October 2005

Most problems of fluid-structure interaction are unwanted side effects stemming from the necessity of placing some mechanical structure in a flow field. Fluid flows enveloping fixed, bluff objects almost invariably induce effects such as time-varying pressures over the object and turbulent wakes behind it which possess various degrees of organization. When, in addition, the object is mechanically permitted to move, through degrees of elasticity assigned to its mountings, the body deflects under the fluid pressures, thereby altering the boundary conditions of the initial flow problem. Such alterations in the flow conditions typically result in a problem of fluid-structure interaction, often time-dependent. Many problems of this type evidence vibrational instabilities of the self-excited type. The present paper discusses those among such problems which have come to be known by the names flutter, vortex-induced excitation, galloping, and buffeting. In the great majority of these problems the finer details of the fluid flows are not well known or conveniently predictable, and it becomes necessary to investigate the phenomena experimentally. It is often possible, however, to create, in an overall way, an adequate mathematical model for each phenomenon on an empirical basis, leaving appropriate unknown fluid-dynamic coefficients to be evaluated from experiment through the application of techniques of system identification. The paper discusses aspects of both the physical phenomena of these problems and their mathematical models in a number of representative cases.
Process excited vibration in circular saws
Authors: Mote C. D.
Published: October 2005

Process excitation in the cutting of most materials induces significant vibration in the cutter which in turn causes significant, direct economic loss from material waste, poor quality machined surfaces, and reduced tool life. The lecture will discuss the physical and mathematical mechanism of transverse instability in thin, rotating cutters. The observed relationship between the theoretical instability conditions and the actual cutter performance will also be discussed and demonstrated with laboratory and production data. Lateral surface guides, whose function is to hold the plate orientation during the cutting process, also excite the plate to instabilities. The number, orientation, and kinetic properties of these guides are critical to their performance. The analysis of this problem will also be discussed.
Real-time signal processing of noise data using cross-property techniques
Authors: Keller Anton C.
Published: October 2005

Before the advent of realtime one-third-octave analyzers, which give a better insight into different noise characteristics and provide a significant increase in the speed with which acoustic data can be processed, noise signals were analyzed in serial fashion into octave, one-third octave, or “narrow-band” results. More recently, narrow-band real time analysis techniques have provided an entire new dimension to our ability to interpret acoustic phenomena and isolate sources of noise. However, the most significant advance has undoubtedly been the introduction of the Fast Fourier Transform and its implementation in a real-time processing mode. This gives the ability to process signals with respect to their phase, as well as cause and effect, to a degree that was previously impossible. This paper deals with the application of two-channel signal processing techniques, using FFT, to several signal and system related measurement problems.
Recent applications of coherence function techniques in diagnosis and prediction of noise
Authors: Seybert Andrew F. , Crocker Malcolm J.
Published: October 2005

This paper discusses the application of coherence function techniques in developing semiempirical models of acoustical systems, with particular application to diesel engine noise. Pressure transducers, mounted in each of the combustion chambers, measured the cylinder pressures and a microphone mounted 1 m to one side of the engine measured the sound pressure. The frequency responses between each cylinder and the noise were computed. The frequency responses were used to predict the effect on the engine noise of varying combustion parameters such as injection timing. Previously, the effect on noise of combustion parameters has been determined by empirical means only. It is also shown that even though the inputs are highly coherent, it is still possible to determine the frequency responses for the case where the inputs are identical but delayed in time by fixed amounts, as is the case for multicylinder pumps, engines, and compressors.
Self-excited vibrations of overhead transmission lines
Authors: Edwards A. T.
Published: October 2005

There are three principal types of vibration which occur on overhead lines and which are of engineering significance. These are classified as aeolian- or vortex-shedding-induced, wake-induced, and the bluff-body or galloping type of mechanical oscillation. The latter two are self-excited and are discussed in some detail. Theoretical studies are compared with experimental results and a number of methods of control are described.
Lateralization of signals without onsets
Authors: Hafter E. R. , Gilkey R. H. , Dye R. H.
Published: October 2005

The importance of ongoing temporal information for the lateralization of low-frequency tones was examined by presenting signals with no discernible onsets or offsets. Listeners heard continuous noise, either correlated or uncorrelated interaurally. During two intervals, the noise disappeared leaving a 500-Hz tone. The interaural phase of the tone varied between intervals, and detection of the phase shift was measured using forced-choice psychophysics. Since sound was always present, the effect of removing the noise can be thought of as primarily one of adding temporal organization to the 500-Hz channels. With uncorrelated noise, performance was slightly worse than that found with tone bursts presented in the quiet, while with correlated noise there was virtually no effect of the missing onsets. There was an interaction with duration: Below 100 msec, detection with the correlated noise became suddenly worse, breaking away from lateralization in the quiet. With uncorrelated noise, this steep break occurred for durations less than 200 msec. Most importantly, however, the smallness of the effects at longer duration raises serious questions for models which presuppose that most of the temporal information in binaural hearing is carried in the transients. [Work supported by NIH: NS-07787.]
Comparison of interaural time difference thresholds for speech, speech spectrum noise, and pure tones
Authors: Hawkins David B. , Young Lamar L.
Published: October 2005

The interaural time difference threshold for speech has been reported to be approximately 30 μsec [E. Cherry and B. Sayers, J. Acoust. Soc. Am. 28, 889&–895 (1956)]. This value is substantially larger than the 10-μsec figure reported for broad band noise signals by other experimenters [e.g., R. Klumpp and H. Eady, J. Acoust. Soc. Am. 28, 859–860 (1956)]. In the two studies just mentioned, however, different subjects and psychoacoustical methods were employed; thus, it is unclear as to whether larger Δt's are indeed needed to lateralize speech signals. The purpose of this experiment, therefore, was to compare lateralization performance for speech and nonspeech stimuli. Interaural time difference thresholds were obtained for speech, speech-spectrum noise, speech-modulated noise, and 200-, 500-, and 1000-Hz sinusoids for the same subjects using a 2IFC experimental paradigm. Under these conditions, speech and speech-modulated noise yielded essentially the same interaural time difference thresholds. In addition, smaller Δt's for 75% correct performance were needed for the broad band noise than for the pure tone stimuli. [Supported by a grant from NINCDS.]
Categorical perception of both simple auditory and visual stimuli
Authors: Pastore R. E. , Friedman C. , Baffuto K. J. , Fink E. A.
Published: October 2005

Until recently, categorical perception was considered to be a unique property of speech perception universal to all languages. A number of studies have demonstrated this phenomenon with complex, nonspeech auditory stimuli, but not with simple auditory stimuli. Categorical perception now is considered to be a property of complex acoustic signal processing which is of central importance to speech perception. This paper describes two studies demonstrating categorical perception: one in the auditory and one in the visual modality. In the vision study, the frequency of a single flickering light was varied. In the auditory study, the intensity of a tonal stimulus was varied in the presence of a fixed pedestal. Both studies find (a) clear ‘labeling functions separated by a sharp boundary; (b) discrimination functions with a peak at the category boundary and chance performance within categories; and (c) a high degree of correspondence between the actual discrimination data and the data predicted on the basis of the labeling data. The interpretation of these studies provides an added dimension to understanding the nature of categorical perception.
Pitch and bandwidth effects in consonant transition perception
Authors: Haggard Mark
Published: October 2005

Mechanisms for the coding of speech sounds may be suggested by a knowledge of factors not having cue value but affecting the discriminability of cues. Two experiments were run on adolescent listeners' identification of /bε, dε/ with near-boundary values of synthetic F2 and F3 transitions; effectively, this measures discrimination. The trajectory of F0 over the duration of the formant transitions could be high falling or low rising but first-pulse timing was controlled. Overall, F0 had no effect; low F0 conditions gave intermediate performance, while high F0 gave high performance for narrow F2 bandwidths but low performance for broad F2 bandwidths. These results are consistent with joint operation of peak-picking and spectral-shift modes of spectral analysis but not with periodicity analysis for the F2 and F3 region. Biasing effects indicating secondary cue value did emerge; for example both narrow bandwidths and high F0 favored /bε/ responses. Such effects have to be explained partly as valid perceptual inferences to articulatory events and partly as byproducts of auditory transforms.
Categorical perception along an oral-nasal continuum
Authors: Mandler Roland C.
Published: October 2005

The oral-nasal distinction for bilabial and alveolar stops was investigated using CV stimuli made with a computer-controlled OVE III synthesizer. For each place of articulation, two continua were produced. In the first continua, vowel branch amplitude and bandwidth increments of F1 and F2 were covaried during stop closure in nine equal steps from [ma] to [ba] or [na] to [da], the amplitude over the range 0 to −25 dB (relative to the vowel steady state) and the bandwidth increments over the ranges 170 to 35 Hz (F1) and 320 to 50 Hz (F2). In the second continuum, nasal branch amplitude was varied during closure over the range −6 to −24 dB (relative to the vowel steady state). Identification tests and same-different discrimination tests were made for all four continua and given to 13 subjects. The interstimulus interval in the discrimination test was 0.5 sec. Subjects perceived the stimuli categorically: crossovers in identification functions matched peaks in discrimination functions for both kinds of continuum and both places of articulation.
Temporal fine-structure and vowel perception
Authors: Scott Brian L.
Published: October 2005

At the 90th meeting of the Acoustical Society 1 presented evidence that the temporal fine structure of vowel waveforms can influence their categorization. The present study investigates the use of the temporal fine-structure relationships discovered previously to synthesize vowels using simple sine-wave building blocks. The two “building blocks” were (1) two sine waves added together (500 and 2200 Hz) and (2) a 500-Hz sine wave alone. The vowels /ei/, /i/, /ai/, /ou/, /iu/ were synthesized by adding or subtracting individual cycles of the “building blocks” while fundamental frequency was held constant (100 Hz). The series was heard unambiguously as /ei/, /i/, /ai, /ou/, /iu/ by four observers listening to the sounds in ten different orders. The results are anomalous on two counts: (1) the sounds heard as /ei/ and /ou/ were perceived as diphthongs although no frequency glides existed and (2) the results can not be explained solely in terms of conventional spectral analyses. [Supported by NIH grant NS 03856 to CID.]
Perception of /r/ and /l/ in syllable-initial and syllable-final position
Authors: McGovern Katharine , Strange Winifred
Published: October 2005

American English liquids have been considered intermediate between stop consonants and vowels acoustically, articulatorily, phonologically, and perceptually. Liquids are unique among English phonemes in requiring different notation in phonetic transcription depending on syllable position. Cutting [Percep. Psychophys. 16, 601–612 (1974)] found position-dependent ear advantages for liquids in a dichotic listening task. The present study used a categorical perception paradigm to provide answers to three questions: (1) Does perception differ for liquids in syllable-initial and syllable-final position? (2) Are liquids perceived categorically in the context of the vowel /i/? (3) Does perception of the isolated third formant (F3), the only acoustic difference among the tokens, predict perception of the speech tokens? Fifteen subjects listened to two synthetic series-/li/ to /ri/ and /il/ to /ir/-in which stepwise variations of F3 parameters cued the difference in consonant identity. Results indicated that: (1) perception did not differ between syllable positions, (2) all liquids were perceived categorically, and (3) discrimination of the isolated F3 did not account for the perception of the speech sounds. [Work supported by NIMH, NICHD.]
An INDSCAL analysis of perceptual confusions of vowels in four consonantal environments
Authors: Wilson H. F. , Bond Z. S.
Published: October 2005

Confusions of nine monopthongal English vowels, /i, I, ε, æ, ʌ, a, u, U, ɔ/, excerpted from different phonetic contexts were analyzed by INDSCAL. The phonetic contexts were neutral (h___d), nasal (n___n), initial /l/ (l___C), and initial /r/ (r___C). The parameters and variance accounted for from a three-dimensional analysis were interpreted as “tongue height” (30%), “low front-back” (30%), and “tongue advancement” (23%). The relative weights of phonetic context on each dimension were obtained. Vowels from a neutral context had near equal weights on all three dimensions, dimensional weights on vowels from /l/ and /r/ contexts decreased, and dimensional weights on vowels from a nasal context increased, over the three dimensions.