bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustical communication between the members of the oriental hornet (Vespa orientalis) colony
Authors: Ishay Jacob , Schwartz Aladar
Published: October 2005

In previous works [J. Ishay and A. Schwartz, Insectes Sociaux 12, 383–388 (1965); L. Schaudinschky and J. Ishay, J. Acout. Soc. Amer. 44, 1290–1301 (1968)], we described the noise occurring in a hornets' nest, especially the “hunger signals” of the larvae, and the noise made by the workers' “dances” around the queen. The present work is an analysis of the whole acoustical spectrum of noise made by individual larvae and by adults, the conclusion being that the “hunger signals” sent out by the larvae of males, of workers, and of queens, differ from one another and from the “hunger signal” sent out by the corresponding individuals species of hornet—the Vespa crabro—which is widely found in Euroasia. Apart from this, two different kinds of noise created by the workers themselves may be clearly distinguished. They too, have been found to be not only dissimilar to each other, but also to the “hunger signals” emitted by the larvae. The “musical instrument” on which the nest members “play” is the comb, its supplementary use thus being the transmission of information by acoustical methods. The different “channels” used for this purpose ensure that transmission of one “message” does not interfere with any other.
Generation of acoustic waves during the passage of a shock wave through a heated gaseous element
Authors: Hamernik Roger P. , Dosanjh Darshan S.
Published: October 2005

The generation of acoustic waves during the interaction of a reflected normal shock front generated in a shock tube, and a two-dimensional highly heated turbulent fluid element are reported. The heated gaseous element was created at a predetermined time by exploding a fine-gauge copper wire in the drift flow of the incident shock wave. The transient interaction phenomena were systematically recorded using both μsec spark schlieren and interferometric photographs, as well as a high-speed framing camera in conjunction with an interferometer and schlieren optical system. These data revealed that (1) a cylindrical progressive band of acoustic waves centered on the transmitted heated element is generated behind the reflected shock front. The leading edge of the acoustic-wave front was found to have an alternate compression-rarefraction type of density distribution along its circumference. (2) The reflected normal shock wave is distorted during its passage through the heated element. (3) The dynamic behavior of the heated element is radically altered. The density amplitude distribution through the acoustic-wave system is shown to be in general agreement with the analytical predictions of Chisnell [Proc. R. Soc. Lond. 232, 350(1955)], which were based upon shock-contact surface interaction theory.
Ultrasonic surface wave detection by optical interferometry
Authors: Palmer C. Harvey
Published: October 2005

The use of optical interferometry for measurement of ultrasonic surface waves has been limited heretofore by the necessity of maintaining the surface under test within a fraction of a wavelength of light of some fixed position. A new technique, using two coherent light beams focused on the specimen surface, avoids this limitation. This technique is useful for directly recording standing-wave ratio, attenuation, transmission, harmonic content, and other characteristics of surface waves at frequencies ranging from audio to beyond 200 MHz. In addition to excellent sensitivity, the method allows absolute calibration of the acoustic wave amplitude.
Insulating houses against aircraft noise
Authors: Donato R. J.
Published: October 2005

A set of rules is devised whereby the component types of the envelope of a house or an apartment may be chosen from a knowledge of their acoustical properties, their relative areas, the degree of intrusive sound that may be tolerated, and the noise exposure forecast contours.
Elastic waveguide propagation in an infinite isotropic solid cylinder that is subjected to a static axial stress and strain
Authors: Mott G.
Published: October 2005

Making use of newly derived equations for dc-ac coupled elastic motion, the effect of a static axial stress and strain upon the velocity of the lowest-order flexural mode in solid circular cylinders has been demonstrated. It is rigorously shown that the “transverse” wave in a stretch string configuration is the general form of which the lowest-order Pochammer mode is the special case, i.e., for zero static stress. Applications of the results to stringed instruments, high-speed turbines, and deep-sea vehicles are briefly discussed.
Pitch of sound bursts with continuous or discontinuous change of frequency
Authors: Nábělek I. V. , Nábělek A. K. , Hirsh I. J.
Published: October 2005

In an earlier study [I. V. Nábělek, A. K. Nábělek, and I. J. Hirsh, J. Acoust. Soc. Am. 48, 536–553 (1970)] of the pitch of a sound burst with two frequencies connected by a linear frequency change (a glide), it was found that the pair of frequencies, initial and final, are sometimes perceptually fused and sometimes perceptually separated. In the present study, the pitch of the same kind of bursts is compared with the pitch bursts in which the glide is supplanted by a pause. The method of adjustment was used. Some differences in the pitch perception of bursts with glides and those with pauses were found. Prolongation of the glide made separation more difficult and fusion easier, while prolongation of the pause made separation easier and fusion more difficult. Prolongation of either the glide or the final frequency of the burst casued the pitch to be shifted toward the final frequency, while the prolongation of the pause (0–40 msec) did not change the pitch. For an explanation of this discrepancy it seems to be necessary to take central processing into consideration.
Notes on the electrophonic hearing effect
Authors: Perrott David R. , Higgins Paul
Published: October 2005

The results of the present experiment indicate that the electrophonic effect can be readily explained as a microphonic phenomena. Electrophonic stimulation produced bone vibrations of sufficient amplitude to account for the sound heard by the listener.
Sound pressure in water from a source in air and vice versa
Authors: Young Robert W.
Published: October 2005

Sound-pressure level Lp at a depth d, in water, due to a point source in air at a distance h above the water surface, may be calculated from Lp = [Ls −7 +20 log(cosθ)]−20 log(r/rs), where Ls the source level is the sound-pressure level in air at distance rs from the source, r is the straight-line distance to the receiving hydrophone from a virtual sound source situated under the actual source at height h′ = (c1/c2) h above the surface; c1 and c2 are the respective speeds of sound in air and water; θ is the angle between the vertical and the line of length r. Comparisons with various published results obtained by more sophisticated ray-theory show agreement within 1 dB, except at shallow depths and far sidewise from the sound source; agreement within 2 dB is found for new experimental data here presented for sound bursts of frequency 500, 1000, and 2000 Hz, and h = 3.5 m. For sound originating in water at depth d below the surface, the sound-pressure level received in air is to be calculated from Lp = Ls − 52 + 40 log(cosθ) − 20 log(r/rs), where Ls is the source level, at rs, in the water. Experimental data obtained with a sound source in the water at depth d = 5.6 m, and frequencies of 500, 1000, or 2000 Hz, are in agreement with this equation, mostly within 2 dB, for receiving positions in air 1 or 2 m above the water and offsets as great as 3 m.
Comments on “Torsional vibration of an elastic solid containing a penny-shaped crack” [G. C. Sih and J. F. Loeber, J. Acoust. Soc. Am. 44, 1237–1245 (1968)] and “Normal compression and radial shear waves scattering at a penny-shaped crack in an elastic solid” [G. C. Sih and J. F. Loeber, J. Acoust. Soc. Am. 46, 711–721 (1969)]
Authors: Abo-Zena A. M.
Published: October 2005

This letter points out some errors in the mathematical analysis of the two papers by G. C. Sih and J. F. Loeber, [J. Acoust. Soc. Am. 44, 1237 (1968); 46, 711 (1969)] and discusses the effect of the errors on the results.
On the derivation of a Lagrange-Banta operator for progressive finite-amplitude wave propagation in a dissipative fluid medium
Authors: Fenlon Francis Hugh
Published: October 2005

In this paper, a classical operational solution of the nonlinear wave equation which defines the interaction (to second order) of progressive finite-amplitude (intense) acoustic waves in lossless nondispersive fluids prior to shock formation is approximately extended to include the influence of viscous dissipation on the spatial rate-of-change of the nonlinearly generated spectral components.
Pitch and stimulus fine structure
Authors: Wightman Frederic L.
Published: October 2005

It has often been suggested that the pitch of a complex tone is given by the inverse of the time between peaks in the fine structure of the stimulus waveform. This paper argues that in view of recent empirical evidence such a position is untenable. Fine-structure models of pitch such as the “peak-picker” are phase sensitive; they predict that changes in stimulus fine structure will be accompanied by changes in pitch. Results from several pitch-matching experiments do not support this prediction. Two experiments are described in which pitch matches were made to complex-tone stimuli presented in several different phase configurations. In both experiments the distributions of pitch matches appeared to be the same for all phase configurations. Stimulus fine structure, of course, changed dramatically with phase. Of course, the fact that pitch is insensitive to the relative phases of the stimulus components does not mean that listeners cannot hear the phase changes. In many cases stimuli with the same pitch are perfectly discriminable. It is only pitch that appears to be insensitive to details of wave form fine structure. This leads us to reject the simple fine-structure theories of pitch.
Maximum-likelihood signal processing for a vertical array
Authors: Hinich Melvin J.
Published: October 2005

This paper presents the maximum-likelihood signal processor for steering a vertical array in the vertical direction. The major application is to the estimation of the depth of a distant narrow-band continuous point source in the waveguide. The eigenfunctions of the guide are used to match the array to the received signal The error of the depth estimate is derived as a function of the aperture and geometry of the array, the covariance function of the ambient noise received by the array, and the observation period; assuming that the source and medium are stationary during that period. The processing technique can be applied to any perfect waveguide in which a signal source is detected by an array of sensors.
Precedence effects and auditory cells with long characteristic delays
Authors: McFadden Dennis
Published: October 2005

Recent neurophysiological experiments make it clear that some neurons in the auditory systems of the cat and monkey are responsive to interaural time differences that are larger than the maximum value possible for animals with their headwidths. Discussed here are several possible ways such neurons could be activated in real-world situations, and it is suggested that these neurons might be involved in the suppression of erroneous localization information, the suppression of reverberation, and/or in the analysis for periodicities in the acoustic stimulus.
Some articulatory manifestations of vowel stress
Authors: Mermelstein Paul
Published: October 2005

Variations in jaw and tongue-body position have been studied when the same word is differently stressed but otherwise identically spoken. Differences between the stresses and unstressed cases for the extreme tongue and jaw positions of the vowel sound indicate for the unstressed case a general neutralization, i.e., less extreme articulation relative to some neutral position. In general, our data do not support the existence of physiological limitations that would prevent the articulator from reaching its intended target in the unstressed case. Rather, stress differentiation appears to be preplanned by modifying the vowel target's articulatory representation as well as its temporal features.
Low-cost approach to area-wide noise monitoring
Authors: Siddon T. E. , Harford K. D.
Published: October 2005

The current approach to noise survey work emphasizes the importance of spatial and temporal noise-level variations, with less stress on frequency content. It is shown that a simple clock-switched sound monitoring package, A -weighted at the input stage, and with dynamic range of 45 dB, yields adequate information on which to base a concise, statistical model of the acoustic landscape. Because of the low-cost nature of individual terminal units, a large number of units may be operated simultaneously over an extended area. This ensures that important spatial information is not lost. Such a detailed picture is not possible with the more conventional sequential (point to point) techniques which are normally employed.
Cochlear microphonic and summating potential of the pigeon
Authors: Pierson M.
Published: October 2005

In a reexamination of the cochlear microphonic and summating potential of the avian cochlea, it has been found that their magnitude and characterization are somewhat at variance with that previously reported. It was found that the CM intensity function is linear with a slope of 1 and that the microphonic amplitude may be as large as 1000 μVp-p. Both positive and negative SP were measured in,the basal scala vestibuli of the pigeon. The properties of the SP are similar to those in the mammal inasmuch as the SP is positive at lower frequencies and negative at higher frequencies. The maximum positivity occurs at 500 Hz and amounts to about 200 μV at 100 dB SPL. The maximum negativity occurs at 3–4 kHz and amounts to about 250 μV at 100 dB. Differences in the findings from those perviously reported can be accounted for by noting that the present measurements were made in either the scala tympani proper or in the scala vestibuli. Intracochlear recordings from the recessus tympani tend to agree with previous findings. [Supported by National Institute of Neurological Diseases and Stroke.]
Effects of eight-hour impulse noise exposures on the chinchilla
Authors: Perkins C. , Hamernik R. P. , Henderson D. , Salvi R.
Published: October 2005

Monoaural chinchillas were exposed for eight hours to reverberant, 140-dB peak SPL impulses, presented at the rate of 1/min. The exposure simulated a standard work day. Thresholds were measured before and for 30 days after exposure, using the auditory evoked response. The surface preparation was used to assess the status of the sensory epithelium of the cochlea. The results of this exposure can be divided into two groups. One group had a small 10–30-dB TTS which recovered completely by 30 days. The cochlea had no unusual hair-cell losses. The second group of chinchillas demonstrated as much as a 90-dB TTS across a broad range of frequencies which resolved to a 40–50-dB PTS, The cochleas of these animals had nearly total losses of outer hair cells throughout the entire cochlea, with scattered small losses of inner hair cells. The traumatic potential of this long-term exposure is in contrast with the relatively innocuous effects of exposure to the same impulses for one hour.
Investigation of noise due to structural vibrations using a cross-correlation technique
Authors: Kumar Sudhir , Srivastava Narayan S.
Published: October 2005

In this paper certain basic considerations of dependence of noise on vibrations of surfaces are presented. Relationships between velocities of vibration and acoustic pressure for plane, spherical, and cylindrical waveforms have been discussed. The statistical technique of cross correlation and its physical interpretations are presented, with a discussion of its background and theoretical development for two time-varying signals. The problem of cross-correlating vibration and noise for a given system in a semi-reverberant environment, while taking into account the effects of multiple sources of similar character, surface area contributions, and reflections from the boundaries is discussed next. Expression for percentage contribution from the vibration of an individual component to the total noise pressure has been deduced. The applicability of this method has been shown through a summary report of an investigation of structural-vibration generated noise of a high-powered diesel engine of the GM 645 E series. It is concluded that the method can be successfully applied to investigate quantitatively the vibration-related noise of a complex machine or structural system, even in a semi-reverberant acoustic field and in the presence of multiple noise sources of similar character. Some other applications of this technique have also been pointed out.
Electrophysiological correlates of loudness recruitment in primates: TTS versus masking
Authors: Pugh J. E. , Moody D. B. , Anderson D. J.
Published: October 2005

In an earlier study, excellent agreement was observed between reaction time of a discreet behavioral response, as an index of loudness, and the amplitude of the cochlear whole-nerve action potential (N1), during recovery from a noise-induced TTS in primates. In this experiment, in the same behaviorally trained macaque monkeys with chronic inner-ear electrodes, threshold shifts of similar magnitude to those observed during TTS have been produced by 8-kHz octave-band noise masking. The observed patterns of recruitment, as evidenced by reaction times, are distinctly different for TTS and masking, while those evidenced by N1 amplitude are not. The possible significance, in terms of loudness coding, is discussed.
Organization of auditory cortex in the owl monkey (Aotus trivirgatus)
Authors: Imig T. J. , Ruggero M. A. , Kitzes L. M. , Javel E. , Brugge J. F.
Published: October 2005

The best frequencies of single units and clusters of units in the superior temporal plane of the owl monkey were determined using threshold tone-burst stimulation. Following each experiment, brains were fixed, sectioned, and stained with thionin or cresyl violet. Electrode tracks were reconstructed from these sections and the cortical cytoarchitecture was examined. When the pattern of distribution of best frequencies and the cytoarchitecture are viewed in conjunction, five auditory fields may be defined. The strongest responses occur in two fields: (1) the primary field, which lies on the superior temporal plane caudal to the insula and extends a short distance onto the lateral surface, and (2) the rostral field, which borders the primary field rostrally. Best frequencies are well organized in these fields. Surrounding the primary and rostral fields are three cytoarhitectonically distinct fields. Here best frequencies are more difficult to define. Of these three fields, the most anterior and lateral are organized tonotopically, but we have not determined the organization of the caudomedial field.
Disturbance of sleep by sonic booms
Authors: Griefahn Barbara , Jansen Gerad
Published: October 2005

After a pilot study (two subjects, 19 nights), we tested two different subjects during 57 nights, administering sonic booms (1 mbar, 300 msec; sound level in the bedroom 80–85 dBA and recording EEG and peripheral blood volume. After five nights without noise, 35 nights with either two or four sonic booms (alternately) were applied. After six more nights without noise, four nights with eight and 16 bangs alternately followed. The last seven nights were used as a comparison phase. Results showed that disturbance was obvious during all periods of noise. No adaptation could be observed during any of the experiments. On the contrary, during the night with four bangs there was a tendency for compensation, e.g., in the last two-thirds of nights with four bangs, the total time of deep sleep was comparable with the nights without any noise.
Causality correlations of jet noise using a shadowgraph technique for source detection
Authors: Rackl R. , Siddon T. E.
Published: October 2005

The “source” of “causal” signal is produced by a low-power laser beam incident on a photodiode. The beam passes through a turbulent flow, measuring light-intensity fluctuations proportional to the two-dimensional Laplacian of density (principle of shadowgraph). This gives an approximation to the source term in the dilatation model of jet noise. The diode signal is cross-correlated with the farfield sound, producing a causality correlation function. The method gives only a linewise resolution of the source region since the beam integrates the conditions along its path. This technique is potentially superior to the insertion of probes measuring velocity or pressure, since the flow is not disturbed and no extra noise due to turbulence-probe interaction is generated. The source region (about the first 10 diameters) of a 20-mm-diameter model jet was surveyed by moving the laser beam radially and axially. The resulting distribution of causality data are presented for different exit Mach numbers and farfield microphone positions. For the particular nozzle used, the results suggest strong noise radiation from the immediate vicinity of the nozzle lip. Work is continuing to establish the quantitative significance of the measured correlation signatures. The development indicates a new powerful technique to be used in the investigation and optimization of jet noise suppression devices. [This work has been supported by the General Electric Company under their contract No. DOT-OS-30034.]
An evaluation of the Lincoln Laboratory speech recognition system
Authors: Wiesen R. A. , Forgie J. W.
Published: October 2005

The current version of the Lincoln speech understanding system employs a vocabulary of about 250 words with a grammar permitting some five million sentences. The acoustic-phonetic and linguistic analyses were developed using a large corpus of data, including many sentences from this grammar. The primary purpose of the research reported here is to permit an evaluation of the system, independent of any input data used in developing the system. Six male subjects each formulated and spoke 25 sentences using charts depicting legal constructs. The processing time for each sentence was about one minute, after which the system displayed what it thought was spoken. Somewhat later, each subject returned to repeat the list of the sentences which he had formulated earlier. Without any adjustments in the system per speaker, about 50% of the sentences were completely correctly recognized for each subject in both situations. This statistic gives very little insight into system's performance, and data analyses will be presented that attempt to portray the strengths and weaknesses of the system. Major emphasis will be given to modifications in acoustic-phonetic analysis suggested by the data. [This work was sponsored by the Advanced Research Projects Agency of the Department of Defense.]
Propagation of severe-storm infrasound to ionospheric heights: a narrow-band atmospheric filter
Authors: Georges T. M. , Jones R. Michael
Published: October 2005

We set out to model theoretically the spectral features of infrasound observed in the ionosphere and believed to be radiated by severe thunderstorms. We explain the dominant 2–5-min wave period as the effect of atmospheric filtering; shorter periods are excessively attenuated by absorption in transit to the ionosphere, and longer periods are attenuated in portions of the atmosphere where the waves are evanescent because their frequencies are below the acoustic cutoff. An observed spectral “fine structure” within the 2–5-min band is explained in terms of resonant interactions between the waves and the atmospheric temperature structure. Accurate quantitative modeling of all these details of the storm-to-ionosphere transmission coefficient requires numerical integration of the acoustic-gravity wave equation, including the effects of ground reflection and partial reflections in atmosphere.
Atmospheric measurements of acoustic phase coherence
Authors: Brown E. H. , Keeler R. J.
Published: October 2005

The phase coherence of an acoustic wave propagating through atmospheric temperature and velocity fluctuations determines the maximum useable range of an atmospheric echosonde. Phase coherence measurements were made for sound propagating through atmospheric turbulence from a source mounted on top of a 500-ft meterological tower. The measurements were made in conjunction with other atmospheric acoustic and gravity wave experiments, including operation of a bistatic echosonde. Throughout the observations, instrumentation on the tower at various heights provided mean winds and temperatures and values of the turbulence structure constants CT and Cv. The results are compared with theoretical predictions and with the few previous experimental observations.
Fundamental-frequency contours of auxiliary phrases in English
Authors: Allen J. , O'Shaughnessy D.
Published: October 2005

Computationally based speech speech understanding and text-to-speech systems require knowledge of the relation of the fundamental frequency of the speech waveform to the underlying syntax, semantics, and pragmatics of the utterance. To investigate several of the many factors known to affect the fundamental-frequency trajectory in an utterance, an extensive corpus of English sentences with varied verbal auxiliary phrases was recorded by three speakers. These phrasal units were chosen for study because they are syntactically well-behaved and exhibit interesting fundamental-frequency contours. Plots of these contours were obtained by computer and analyzed to discover syntactic and semantic correlations with the fundamental frequency. Sentence adverbials, negative elements, subject quantifiers, and certain modals were found to have systematic effects on the auxiliary phrasal contour. These phenomena were viewed in terms of an “operator-nucleus” model, where the propostional, nuclear content of a sentence leads to a basic fundamental-frequency contour, and the presence of additional sentential “operators” (such as adverbs, modals), which express the feeling of the speaker, cause specific modifications to the contour.
Perceptual measure of cue variability in production under different speaking conditions
Authors: Harris M. S. , Umeda N.
Published: October 2005

In the first pilot study of an extensive investigation into the variability of cue production and cue utilization in perception, subjects were asked to identify which member of a pair of internal open juncture phrases (grey day—grade A) they heard. Test phrases were spoken by a male speaker (1) in isolation, and (2) in context and edited from the context. In condition 1, 16 subjects responded with less than 3% errors. In condition 2, 24 subjects yielded an error rate of 20%. It seems that cues used by the speaker in condition 1 are not present to the same degree in condition 2, causing a breakdown in performance without the aid of contextual information. The results support the hypothesis that in speech production there are adjustments in cue formation according to speaking situation. We believe that on the listener's side, as well, in accordance with contextual aid, noise level, meaningfulness, familiarity, etc., there must be variable utilization of cues that are present in the speech wave. Results from extensive studies on cue variability in production and perception are presented.
Illinois motor-vehicle noise survey
Authors: Nechvatal Michael F. , Hellweg Robert D.
Published: October 2005

A motor-vehicle noise survey was performed to assist the development of the proposed Illinois motor-vehicle noise regulations. In-use A-weighted sound levels were measured by the Illinois Environmental Protection Agency during vehicular passbys. The motor vehicles were separated into five classes: heavy trucks (GVW: over 24 000 lb); light-medium trucks (GVW: 8000–14 000 lb); cars and light trucks (GVW: under 8000 lb); and motorcycles. Sound levels were measured for three modes of vehicle operation: acceleration from rest; under 35 mph cruise; and over 35 mph cruise. Statistical distributions for each vehicle type and operating mode are presented and compared to the proposed Illinois motor-vehicle regulations.
Noise tests of target-type reversers for engine-over-the-wing application
Authors: Stone J. R. , Gutierrez O. A.
Published: October 2005

Target-type thrust reversers have been suggested for use with engine-over-the-wing (CTW) powered-lift aircraft. This paper presents the results of experiments on the noise generated by V-gutter and semicylindrical target reversers with circular and short-aspect-ratio-slot nozzles having equivalent diameters of about 5 cm. No wing was used; however, this is considered to be unimportant because with the airplane on the ground, the wing would not provide reverser noise shielding. The experiments were conducted with cold-flow jet at velocities of 195 to 292 m/sec. At subsonic jet velocities of interest for CTW powered-lift aircraft, the reversers, in addition to being noisier than the nozzles alone, also had a more uniform directional distribution and more high-frequency noise. The reverser shape was much more important than the nozzle shape in determining the reverser noise characteristics. The maximum sideline OASPL varied with the sixth power of the jet velocity over the range tested. The experimental data were correlated in terms of normalized SPL spectra as a function of Strouhal number for various angles along the sideline. The possible effects of aircraft motion were also considered. Using these relations, an estimate was made of the perceived noise level along the 152-m sideline for a typical OTW powered-lift airplane.
Estimating auditory filter shape for tones masked by a notched noise
Authors: Patterson Roy D.
Published: October 2005

A wide-band noise having a deep notch with very sharp edges was used to mask a tone. The notch was centered on the tone and tone threshold was repeatedly measured as the width of the notch was increased from 0.0 to 0.8 times the tone frequency (500, 1000, or 2000 Hz). If it is assumed that the auditory filter is reasonably symmetrical over the range of measurement, then an estimate of the shape of the auditory filter can be obtained from the first derivative of the curve relating tone threshold to the width of the noise notch. The 3-dB bandwidth of the filters obtained is about 0.13 times the center frequency which is about twice the value reported earlier [R. D. Patterson, “Auditory filter shape,” J. Acoust. Soc. Am. 55, 802–809 (1974)] where single sideband noise maskers were used. This discrepancy indicates that in the previous experiments the auditory filter was not centered on the tone, as assumed, but rather was shifted away from the noise to improve the signal-to-noise ratio at the output of the filter.
Behavioral measurement of auditory thresholds in the gerbil
Authors: Alexander C. L. , Clark W. W. , Moody D. B. , Stebbins W. C.
Published: October 2005

A procedure is described for behavioral determination of auditory thresholds in the gerbil. Preliminary findings are presented for North African gerbils, rodents of the subfamily Gerbillinae, family Cricetidae. Animals were trained by operant conditioning techniques with food reinforcement to respond to pure-tone stimulation. Thresholds were determined by a tracking procedure at 17 frequencies from 63 Hz to 50 kHz. Testing was carried out under free-field conditions in an anechoic chamber. Best sensitivity occurred below 2 kHz; the hearing function extended over the entire range of frequencies tested. Available behavioral data on rodents indicate two distinct classes of hearing functions—one predominant at low frequencies (e.g., kangaroo rat and chinchilla), the other at high frequencies (rat and mouse). The guinea pig with broad midrange hearing is an exception. The gerbil's hearing is most characteristic of the first class. These findings, along with the anatomical evidence of auditory specialization, suggest that the gerbil ear is highly adapted to its desert environment.
An anomolous influence of tonal context on frequency discrimination
Authors: Wroton H. W. , Watson C. S.
Published: October 2005

In several recent papers we have shown that frequency discrimination can be degraded by other tones which occur immediately before or after the test tone. In the present study a 40-msec test tone was always preceded by a 300-msec “leader” tone and followed by a 150-msec “trailer” tone. When the frequency of the leader-trailer tones are both 440 Hz, it is very difficult to discriminate between test tones of 435 and 445 Hz. Test tones of 438 and 448 Hz, however, can be discriminated almost perfectly. In other words, test tone frequencies that are symmetrically displaced above and below that of the leader-trailer are very difficult to discriminate; those displaced asymmetrically about that frequency can be much more easily discriminated. This effect of the leader-trailer on discrimination ranges from minimum to maximum within a smaller frequency band than can be accounted for by most critical-band-oriented theories of auditory frequency resolution.
Nonmonotonic behavior of distortion product 2f1 − f2: psychophysical observations
Authors: Hall J. L.
Published: October 2005

A detailed study was made of the amplitude and phase characteristics of auditory distortion product 2f1 − f2 in the neighborhood of an amplitude minimum. For f2 = 1.0, 1.2, and 1.4 kHz, f1 was varied from 0.68⋅f2 to 0.88⋅f2, and the (equal) intensity of the two primary tones was varied from 50 to 70 dB SPL. For the one subject investigated, the amplitude of the 2f1 − f2 distortion product exhibited a single mimimum in the portion of the f1/f2 vs intensity plane explored. The value of f1/f2 at the minimum was 0.8 and was roughly constant for various frequencies of f2. The primary-tone amplitude at the minimum decreased with increasing f2 from 60 dB SPL at 1 kHz to less than 50 dB SPL at 1.4 kHz. The 2f1 − f2 phase in the neighborhood of the null was complicated. It changed abruptly at the minimum, it changed more rapidly with f1/f2 at primary-tone intensities below the null than above, and it changed slowly with primary-tone intensity at f1/f2 ratios both below and above the null. Therefore, a complete circuit around the null in the f1/f2 vs intensity plane resulted in a change of 2f1 − f2 phase of 360°.
Amplitude and phase measurements of combination tones (2f1 − f2) and (f2 − f1)
Authors: Shipley James , Matthews John W.
Published: October 2005

Amplitude and phase characteristics of the two most audible combination tones (2f1 − f2) and (f2 − f1) were measured psychoacoustically on four subjects using the cancellation method. Digital stimulus generation allowed for exact phase control and continuous phase shifting. For equal level stimulus tones (f1 and f2) in cosine phase, the results generally corroborate earlier findings. That is, the amplitude of (2f1 − f2) and (f2 − f1) both decrease with increasing f2/f1 with slight changes as a function of stimulus level; (f2 − f1) phase remains relatively constant with respect to stimulus phase as a function of f2/f1, while (2f1 − f2) phase increases dramatically with increasing f2/f1. The present study covers a wide range of primary frequencies and frequency ratios; it also presents data for both (2f1 − f2) and (f2 − f1) from the same subject. Previously unreported combination-tone pitch shift as a function of cancellation-tone phase is also described.
Simultaneous two-channel frequency difference limen
Authors: Ahroon W. A. , Pastore R. E. , Wolz J.
Published: October 2005

The ability of trained observers to monitor two channels in a frequency discrimination inclusive OR paradigm was examined, using clearly detectable signals. The various discrimination tasks involved both (1) the simultaneous monitoring and (2) the single-channel monitoring of simultaneous, independently presented signal events in each earphone channel, as well as (3) the monitoring of events restricted to a single fixed channel. The effects of critical bandwidth limitations on the ability of the observer to perform the tasks was explored. The results are compared with those of two-channel detection tasks in which the ability of the observers to perform is effected by signal frequency separation relative to the critical bandwidth.
Interface waves for a flow-excited cavity in the vicinity of resonance
Authors: Elder S. A.
Published: October 2005

Using computer-assisted synchronous hot-wire technique, longitudinal velocity profiles of the traveling interface wave have been mapped for a cavity excited in the vicinity of its lowest resonant mode. The shear layer perturbed by the oscillation had approximate two-dimensional symmetry for the apparatus used. Near resonance, the phase of the interface wave at the leading edge is not far from that of the local acoustic particle velocity. Vorticity fluctuations travel at a somewhat irregular pace downstream, requiring about one-half cycle to move from leading to trailing edge. Circulation reaches peak value near the center of the cavity mouth. Maximum transverse displacement amplitude of the interface is roughly equal to the width of the shear layer at midpath. Significance of the measurements for understanding the mechanism of flow-excited cavity resonance are discussed. [Work supported by Naval Ship Systems command, under a GHR contract administered by the Naval Ship Research and Development Center.]
Extended reacting impedance characteristics of polyurethane foam in a duct with flow
Authors: Kirk J. J.
Published: October 2005

Extensive use at the Boeing Company of Scottfelt, Grade 900, polyurethane foam as a relatively inexpensive test material for jet-engine nacelle acoustic studies prompted the development of a polyurethane-foam impedance math mode. A math model for an extended reacting foam liner in a duct with flow has been formulated, based on results of previous normal incidence impedance tube tests and math model studies reported at the 86th Meeting of the Acoustical Society of America. Using this model, predictions of the complex axial wavenumber are compared to measurements of firmness 4 Scottfelt in the Boeing/Wichita Grazing Flow Impedance Tube. Results for thicknesses of 1/2 and 1 in. at duct Mach numbers of 0, 0.35, and 0.5 are reported. The extended reacting impedance model has also been incorporated into a duct attenuation prediction program. Predicted attenuations are compared with polyurethane-foam flow duct test results as a further check on the math model.
Sound propagation in a shallow-water duct with randomly rough boundaries
Authors: Kuperman W. A. , Ingenito F.
Published: October 2005

The contributions by randomly rough surface and bottom boundaries to the attenuation coefficients of normal modes in a shallow-water duct are calculated. The usual boundary conditions are replaced by the conditions derived in the previous paper for randomly rough boundaries. It is shown that, to order σ2, where σ is the rms height of the roughness, the effect is to add an imaginary part to the modal wavenumber, which can be interpreted as a modal attenuation coefficient. The modal attenuation coefficients can easily be calculated from the results of the unperturbed (smooth boundary) case. Calculated results are presented for realistic ocean parameters.
Air impedance-tube technique for measuring the acoustic properties of wet sediment samples
Authors: Martin F. D.
Published: October 2005

An impedance tube ( Brüel & Kjaer type 4002), originally designed for air acoustic measurements, was modified for use in making attenuation measurements on ocean bottom sediment samples. The measurements are made by placing sediment samples in holders terminated by a reflector plate, the length of which is selected to be equal to the sample length times the ratio of the sound velocity in the plate to the approximate velocity in the sediment. Since sound velocities for most sediments vary from about 1300 to 1700 m/sec, it appears that variations in reflectivity with frequency, which are a function of sediment velocity and attenuation, may be measured with this technique. The present technique differs from other methods used for sediment attenuation studies in that measurements are made in air instead of water. To evaluate the method, an initial set of measurements was made to determine the acoustic properties of water-kaolinite mixtures. Preliminary data analysis indicates that the frequency dependence of the acoustic properties of wet sediment samples can be measured over the range from 1 to 10 kHz by using an impedance tube in air, together with a series of different-length sample holders. The results are compared to measurements made with other techniques.
Auditory discrimination among speakers in the presence of masking noise
Authors: Hall J. L.
Published: October 2005

The influence of masking noise on the ability of listeners to distinguish among speakers was measured for noise-to-signal ratios of − 20 dB to + 10 dB. The prerecorded stimulus ensemble contained 15 utterances: three test sentences, each spoken by five speakers. Each trial consisted of two different test sentences, spoken by the same or different speakers with equal probability. Masker level was the same for the two utterances in a trial. The subjects' task was to judge whether the two utterances were spoken by the same or by different speakers. Five listeners unfamiliar with the speakers took part in the experiment. Percentage of correct responses decreased from 80% for a noise-to-signal ratio of − 20 dB to 65% for a noise-to-signal ratio of + 10 dB (chance performance = 50%), while response time increased monotonically. Multidimensional scaling techniques were used to determine those speakers for whom discrimination performance was most sensitive to masking noise. Continuing experiments with other signal degradations are outlined.
Errors and latencies for same-different judgments of dichotic CV syllables at various stimulus onset asynchronies (SOAs)
Authors: Repp Bruno H.
Published: October 2005

Three studies were conducted using this paradigm. The major independent variables were SOA and the number of feature contrasts (FC) between the syllables to be compared. Errors and latencies were found to decrease systematically with SOA and with FC. The effect of FC on latencies persisted over at least 500-msec SOA, which argues against comparisons of “holistic” phonemes after encoding is completed. The third study included variations in pitch and predictability of this variation (blocked versus random) as additional factors. They were found to have dramatic effects at very short SOAs but surprisingly little influence at longer SOAs. The results are discussed with reference to a two-process model of dichotic interaction: “integration” at very short SOAs versus “perceptual noise” at longer SOAs. Evidence for integration was seen in the frequency occurrence of incorrect “same” responses at short SOAs. Dichotic syllables that are not integrated are assumed to be compared after being categorized, the major evidence being a negative relationship between intelligibility and incorrect “different” responses.
Effect of stimulus bandwidth and type of masker presentation on the function relating detection performance to signal duration
Authors: Miller Theodore H. , Dolan Terrence R.
Published: October 2005

It has been shown that, when a narrow-bandpass filter is employed with a pulsed masker, signal detectability in the homophasic condition increases monotonically as signal duration decreases. In addition, pulsing the masker has been found to result in a decrement in antiphasic detection performance. The present study was designed to examine the effect of the interaction of stimulus bandwidth and type of masker presentation on the function relating detection performance to signal duration in homophasic and antiphasic conditions. Two interaural phase relations, N0S0 (homophasic) and N0Sπ (antiphasic), two types of masker presentation (continuous and pulsed), two bandpass filters (50 Hz and 200 Hz), and seven signal durations (5, 10, 20, 100, 500, and 1000 msec) were employed. The results of this study indicate that the changes in homophasic detection performance at short signal durations can be explained through consideration of the interaction of signal bandwidth with the assumed internal bandwidth of the auditory system and/or the bandwidth of the external filter employed. The masking-level difference, or MLD, obtained with the pulsed masker varied as the duration of the signal varied, while that obtained with the continuous masker was relatively constant over the entire range of signal durations.
Modifications to the BUDTIF procedure
Authors: Campbell R. A.
Published: October 2005

During the decade that has passed since describing the Block-Up-and-Down, Two-Interval, Forced-choice (BUDTIF) psychophysical procedure in this Journal, several modifications have resulted from actual and computer-simulated experience with the procedure and from discussions of the PEST and UDTR procedures by Taylor, Creelman, Hall, Levitt, and others. Modifications include using a level change decision rule similar to, but more efficient for small N's than, the Weld sequential rule, stopping rules based on the number of decisions and weighted number of trials at a given level, and basing threshold estimates on the mean of revisited levels weighted by the number of trials in the run and restricted to only five levels near the most frequently revisited one. These changes have reduced the effect of starting level on the variance of repeated estimates and the bias in the area of greatest interest for psychoacoustics, that is, stopping rules that yield threshold estimates in less than 100 trials, with the target performance lying at or near the midpoint of the psychometric function. Based on computer simulations, the tendency for the threshold estimate to be biased toward the starting level and for the variance to be related to the absolute difference between the starting and “true” threshold level has been markedly reduced. For example, when starting over a range of 16 logit units, an average of 68 trials per threshold, the starting level effect was less than 0.2 logit unit with the standard deviation being 0.67 unit: This seems to compare favorably with a standard deviation of 0.76 at 68 trials obtained with simulated PEST runs reported by Hall with the starting level always + 4 units. The modifications and simulated results will be reported in greater detail.
Muscular control during speech as reflected by. pharyngeal air pressure
Authors: Abler W. L.
Published: October 2005

Pharyngeal air pressure during continuous speech was monitored under three different experimental conditions: (1) By a tube inserted through the nose, air was introduced into the pharynx at a flow rate exceeding 100 cc/sec; (2) by the same tube, air was withdrawn from the pharynx at a rate exceeding 100 cc/sec; (3) pharyngeal air pressure was allowed to vary in its normal manner. Little difference could be detected between patterns of pharyngeal air-pressure variations accompanying speech under the three different conditions. It was concluded that the speaker at some level “knows” the correct air pressures appropriate to the production of speech sounds. Because the speaker is able to adjust the neuromuscular biases of the speech executors in order to obtain these pressures, speech gestures must be externalizations of internally represented motor plans more abstract than the speech gestures themselves. Thus we can expect to discover no articulatory invariants attending the articulation of speech. The disconnection between the internal representation of motor plans, and the actual neuromuscular events which externalize them, suggests a neural basis for the inventions of writing and signing, without appeal to a gestural theory of the origin of language.