bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioral threshold, cochlear electrophysiology, and cochlear histology in kanamycin-poisoned chinchillas
Authors: Ryan Allen , Dallos Peter , Cheatham Mary Ann
Published: October 2005

Pure-tone thresholds of normal chinchillas were determined by the shock-avoidance procedure. Animals were then given daily kanamycin injections until a shift in threshold was observed. Injections were then terminated, and the threshold shift was allowed to stabilize. Approximately 30 days after the completion of kanamycin treatment, the animals were prepared for electrophysiological data collection. Intracochlear differential electrodes were placed in the first cochlear turn of both ears. Cochlear microphonic, summating potential, and compound action potential responses were collected. Finally, animals were sacrificed and the ears were prepared for histological examination by the surface preparation technique. Correlations between behavioral, electrophysiological, and histological measures are discussed. [This research was supported by grants from NINDS.]
More on the motor organization of speech gestures
Authors: Bell-Berti Fredericka , Harris Katherine S.
Published: October 2005

Observations have been reported of reorganization of motor commands to muscles whose increased contraction will further narrow some portion of the upper vocal tract [Bell-Berti and Harris, J. Acoust. Soc. Am. 55, 384(A) (1974)]. This reorganization manifests itself as a merging of EMG activity for two contiguous speech gestures in some contexts but not in others. We have postulated a rule to predict this reorganization: commands to muscles that close the vocal tract will merge in sequences of gestures in which the vocal tract is being closed. Data have now been recorded from muscles that open the vocal tract to determine if the rule for motor command reorganization for these muscles is the converse of the rule for the closers: commands to muscles that open the vocal tract will merge in sequences of gestures in which the vocal tract is being opened. (Another expression of these rules might be: when a muscle must be shorter for the second element in a sequence than for the first, activity will merge into one continuous burst; when a muscle must be lengthened for the second element of a sequence, activity will be suppressed between commands for the two gestures.) This information may be correlated with the limits of coarticulation at the movement level. Acoustic records will be checked to examine this hypothesis.
Display and interpretation of glottal activity as transduced by external accelerometers
Authors: Henke William L.
Published: October 2005

Small accelerometers (less than 2 g) which are easily affixed directly to external body surfaces in the region of the larynx transduce signals which may be interpreted to yield data on several aspects of glottal activity during phonation. Comparative evaluation of such signals across varying conditions of articulation, transducer locations, gas density (sound velocity), and speaker has suggested the association of specific features of the signals with mechanical and acoustical correlates, e.g., distinct sub- and supraglottal resonances and open and closed portions of the glottal cycle. Correlations between simultaneous signals of two accelerometers or an accelerometer and an audio microphone are used to show propagation characteristics. A contourgraphic or synchronous sequential type of display format driven by an excitation pulse position marking algorithm gives visual prominence both to gradual changes in waveform due to articulation changes and to aperiodic anomalies which are of interest in both normal and pathological cases. Another display format which shows tracks of fundamental frequency and a measure of individual pulse strength emphasizes the more macroscopic or prosodic aspects of phonation.
Function of the posterior cricoarytenoid in speech articulation
Authors: Hirose H. , Ushijima T.
Published: October 2005

The posterior cricoarytenoid (PCA) is known to be the only abductor of the larynx, but its role in speech has not fully been clarified. Recent electromyographic studies reveal active participation of PCA in the production of voiceless consonants and breathy phonation [Hirose and Gay, Phonefica 25, 140 (1972); Folia Phonier. 25, 203 (1973)]. Computer-averaged electromyographic data were obtained from PCA of a Japanese subject who uttered meaningful test words embedded in a frame sentence. The test words were so selected as to contain voiceless consonants, devoiced vowel segments, or geminates in word initial and medial positions. The results indicated that there was consistent increase in PCA activity for the voiceless portion of the test words. The size of the glottal opening was then measured on the same subject by means of the fiberscopic technique. Positive correlation was found between the amount of peak PCA activity for a given voiceless segment and the degree of maximum glottal opening for the same voiceless segment. [This research was supported in part by the National Institute of Dental Research, NIH Grant No. DE-01774.]
Glottal dynamics during Hindi bilabial plosives and the glottal fricative
Authors: Dixit R. Prakash , MacNeilage Peter F.
Published: October 2005

The dynamics of glottal behavior during the production of bilabial plosives and the glottal fricative was investigated in Hindi, which possesses contrasts between aspirated and unaspirated plosives, both in voiced and unvoiced categories. Minimal pairs of meaningful and nonsense words with /p/, /ph/, /b/, /bh/, and /h/ occurring in prevocalic, intervocalic, and postvocalic positions were embedded in the sentence /didi-bolIye/. Photoelectric glottograms together with audio signal were recorded and examined. The results indicate that (1) the opening gesture of the glottis is a necessary condition for the production of the glottal fricative and unaspirated plosives, both voiced and unvoiced; (2) unaspirated plosives, both voiced and unvoiced, may be produced with or without opening gesture of the glottis; (3) regardless of aspiration, voiced plosives are produced with uninterrupted vocal-fold vibrations, whereas unvoiced plosives are not; (4) glottal fricative is produced without interruption of vocal-fold vibrations; (5) duration and extent of glottal opening do not seem to be systematically related; (6) there is no apparent direct correlation between the degree of glottal opening at the time of oral release and the degree of aspiration; (7) the initiation of opening and closing gestures of the glottis, in relation to oral closure and release, respectively, is variously timed for various plosives.
Experimental evaluation of a linear predictive speech compression system based on phonetically balanced (PB) words and sentences
Authors: Chandra Satish , Lin Wen C.
Published: October 2005

In this paper experimental evaluation of a linear predictive speech compression system is described. A 10th-order linear predictor is used assuming an all-pole model. Input speech is bandlimited to 4 kHz and is sampled at 10-kHz rate. Pitch synchronous analysis and synthesis is used. Transmission rate is constant but frame size, for which transmission parameters are sent, is time variant. An on-line intelligibility measurement system [Agrawal and Lin, “An On-Line Speech Intelligibility Measurement System,” IEEE Trans. Audio Electroacoust. AU-22 (1974)] is used for PB word listening tests. This system uses a computer to administer the test, record the listener response, and automatically evaluate it on-line. The compressed speech is bandlimited to 4 kHz. The intelligibility scores of 50 compressed PB words at different transmission rates are compared with original uncompressed PB words. This paper emphasizes the use of PB word intelligibility scores to improve the performance of linear predictive speech compression system. Statistical analysis of intelligibility scores and listener's response are reported. The results of quality comparison of compressed PB sentences at different bit rates are also reported.
Development of the gravitational radiation antenna
Authors: Weber J.
Published: October 2005

A summary is given of the primarily acoustics problems and their solution in development of the gravitational radiation antenna.
Acoustic ray-wave synthesis
Authors: Grace O. D.
Published: October 2005

An acoustic ray-wave synthesis is developed by combining the wave theory methods of Kirchoff with the ray theory methods of Sommerfeld and Runge. The result is a generalization of the Kirchoff integral formulation of the wave equation in which the kernels are ray theory expressions and in which an additional term appears. The ray theory kernels represent the gross properties of the fields, while the extra term represents scattering by the medium and is the additional field required for an exact solution. This extra term is approximately evaluated for the case of backscattering by weak random sound-speed variations. This evaluation shows that, while the source of the scattering lies with the first and second derivatives of the index of refraction, it is the sound derivative that is the dominant source of scattering. Further, a backscattering cross section is derived that agrees with a previously derived result.
Visualization of the “Keller edge wave.”
Authors: New R. , Marcus A. , Mehta A. , Clark J.
Published: October 2005

The Keller geometrical theory of diffraction “GTD” [Keller, Symposium on Microwave Optics, McGill Univ. (1953)] has proven over the past 20 years to be an extremely powerful addition to high-frequency acoustical and optical theories. One important law of GTD is the law of edge diffraction; its import stems from the fact that edge diffraction is second in importance only to geometrical acoustics (the classical ray theory) in forming the scattered field from obstacles. The law of edge diffraction was experimentally demonstrated in one previous case [Senior and Uslenghi, Proc. IEEE 60, No. 11, 1448 (1972)]. We have developed a different method for observing edge diffraction which permits motion visualization of the complete three-dimensional diffraction cone produced by scattering from a variety of wedges. These results have been correlated with theory and their degree of correlation is shown.
Time-harmonic scattering by obstacles surrounded by an inhomogeneous medium
Authors: Shaw R. P.
Published: October 2005

The scattering of time-harmonic waves by obstacles surrounded by an inhomogeneous medium which becomes homogeneous at some distance from the obstacle is discussed. The solution procedure is to use a standard technique such as finite differences in the interior inhomogeneous region up to an outer boundary drawn completely in the homogeneous region on which the unknown and its normal derivative can be related through a Helmholtz integral equation, which in turn is approximated by a set of linear algebraic equations. The interior plus boundary equations form a complete set for the algebraic unknowns. Numerical examples are given for a circular island with both constant and variable surrounding water depth scattering long periodic water waves. The results are equally applicable to plane acoustic wave scattering by a rigid circular cylinder imbedded in an inhomogeneous medium, which may be treated as essentially homogeneous at some distance from the cylinder.
Tuning curves of auditory nerve fibers in the alligator lizard
Authors: Weiss T. F. , Mulroy M. J. , Turner R. G. , Pike C. L.
Published: October 2005

Action potentials were recorded from single units in the auditory nerve with electrodes placed between the ganglion cell bodies and the habenula perforata. Tuning curves of units fell into two distinct populations: a low-frequency group with characteristic frequencies (CF) below 1 kHz, and a high-frequency group with CF above 1 kHz. Units with low CF were located in the part of the nerve that enters the optical region of the basilar papilla, while units with high CF were located in the part of the nerve that enters the basal region of the basilar papilla. Tuning curves from these two regions have markedly different shapes. The sensory epithelium in these two regions differs in presence of the tectorial membrane, orientation of the hair cells, and length of the ciliary tufts. These results suggest that tuning properties of auditory nerve fibers in this animal may not be entirely due to the frequency selectivity of the basilar membrane. [Supported by NIH grants.]
Discharge patterns in auditory nerve of chinchilla to AM tones possessing low subjective pitch
Authors: Javel Eric
Published: October 2005

Temporal aspects of discharges in single primary auditory nerve fibers of the chinchilla were analyzed in response to computer-synthesized three-component sinusoidally amplitude modulated (AM) tones. The stimuli were of the type which, in humans, give rise to a percept of low subjective (residue) pitch. The results indicate that (a) interactions between tonal components exist in responses of units tuned to the component frequencies, the onset of these interactions corresponding roughly to the limit of the existence region for residue pitch; (b) in general, response patterns are related to the temporal features of the stimulus; (c) the responses of units tuned to the component frequencies demonstrate that a portion of activity is locked in phase to the subjective pitch frequency, even in cases producing pitch shift; and (d) units tuned to the low subjective pitch frequencies do not respond to higher-frequency AM tones at low and moderate intensity levels. Taken together, these results imply that the responses of single auditory nerve fibers to AM tones contain sufficient information for a determination of subjective pitch by either temporal fine structure or autocorrelation analysis.
Short-term adaptation in single auditory-nerve fibers—an additive or a multiplicative effect?
Authors: Smith R. L.
Published: October 2005

In response to tone bursts of constant sound intensity, guinea-pig auditory nerve fibers produce a maximum firing rate at the onset, followed by an adaptation to a quasisteady rate within about 150 msec. On the basis of two main experimental findings, we conclude that this adaptation is inherently additive or linear in nature and not the result of a multiplicative or gain change. Basically, a given increment in intensity causes an equal change in firing rate, whether the increment is added before or after adaptation has occurred. In addition, the relative amount of adaptation appearing in the response to a tone of constant intensity, i.e., the ratio of driven onset response to driven steady-state response, is independent of tone-intensity level. When sufficiently high total firing rates are involved, these findings must be modified to include an apparent saturation that occurs at high rates. However, the overall nonlinear stimulus-response relationship may be accounted for by a nonlinearity which precedes the adaptation process and hence does not effect the above relationships.
Anatomy and physiology of the cat trapezoid body
Authors: Brownell W. E.
Published: October 2005

The fibers of the trapezoid body (TB) emerge from the ventral cochlear nucleus (VCN) and stratify into laminae on the basis of fiber diameter. The dorsal layer is a uniform collection of 3–5-μ-diameter fibers which comprise the medium diameter population (MDP). These fibers originate from the spherical cells of the anterior VCN [J. van Noort (1969)]. The large-diameter population (LDP) is composed of 8–15-μ-diameter fibers that arise from globular cells in the VCN [Irving and Harrison, Anat. Rec. 151, 458 (1965)]. Small 1–3-μ-diameter fibers make up the most ventral lamina and are interspersed among the large LDP fibers. Bilateral cochlear nuclei ablations result in almost total TB fiber degeneration. Single unit recordings at the midline demonstrate a dorso-ventral progression of low to high best frequency in the MDP but not in the LDP. Except for latent periods, the discharge characteristics of units in the MDP are the same as those of spherical cells and eighth-nerve fibers for all parameters where comparisons are available. The excitatory response characteristics of units in the LDP are similar to those of MDP fibers. LDP fibers differ in having tuning curves with inhibitory sidebands as well as a lower mean spontaneous rate of discharge. [Supported in part by NIH Grant NS-05237.]
Modality-specific effects of attention on single-unit responses in monkey auditory cortex
Authors: Hocherman S. , Benson D. A. , Goldstein M. H. , Heffner H. E.
Published: October 2005

Single-unit responses were recorded from the primary auditory cortex of rhesus monkeys while they performed a two-choice discrimination in which an auditory cue (either tone burst or noise burst) and a visual cue (either left light or right light) were simultaneously presented. The subject's attention to these auditory and visual cues was manipulated by selectively reinforcing responses to only one modality at a time. Responses of single units to sound stimuli which signaled reinforcement were compared to responses to the same sound stimuli when the visual cues signaled reinforcement. Most units showed differences in the strength of their acoustically evoked responses, as reflected in dot displays and PST histograms. For some units this response was stronger when the reinforced modality was sound, for others light. A few units which could not be acoustically driven under one cue condition could be driven for the other. Usually units were less responsive when studied using identical acoustic signals, with the animal sitting passively without opportunity to receive reward. [Supported in part by NIH Grant No. NS-05143.]
Consonant recognition in noise: sensorineural loss
Authors: Bilger R. C. , Stiegel M. S. , Rose N. R.
Published: October 2005

Consonant recognition in quiet and noise was studied for 18 outpatient listeners who had moderate sensorineural losses. The 16 consonants were presented in a CV context, using three different vowels. Each subject heard 10 lists of 96 nonsense syllables for each condition. Syllables were presented monaurally at approximately 100 dB SPL, noise at 95 dB SPL. For these conditions of signal and noise level, the performance of normally hearing college students (n = 4) was reduced from 90% to 55% correct recognition by the addition of the noise and that of outpatient listeners with normal hearing (n = 6) from 70% to 45% correct recognition. For the 18 listeners with moderate sensorineural losses, the performance of nine was not affected adversely by addition of the noise and that of only five showed a decrement comparable to that seen in normals. The trend was for listeners with low performance in quiet to do as well in noise as they had done in quiet. These results required the use of forced-choice method, as opposed to the write-down technique used in earlier studies, which suggested that listeners with sensorineural loss are more adversely affected by noise than are normals. The present results suggest that the effects of sensorineural loss on speech recognition might be comparable to those of masking noise. [Supported by Public Health Service Award NS 07790.]
Temporal masking effects produced by vowel formants in sensorineural subjects
Authors: Danaher E. M. , Pickett J. M.
Published: October 2005

Deficient discrimination of speech sounds is often found in persons having sensorineural hearing loss. Our previous studies using synthetic vowels indicate that part of the discrimination problem might be due to the upward spread of masking and temporal masking that F1 produces when it is presented at high sound levels. The purpose of this study was to examine the temporal masking of discrimination produced by F1 and to compare it to the “classical” forward and backward masking seen in detection experiments. Detection thresholds were obtained for pure tones which preceded or followed a format-shaped noise. In the discrimination tests, subjects discriminated initial transitions and final transitions in the second formant of a synthetic vowel, while the onset or offset of F1 was varied in relation to the transitions. Results: On the detection task, large (10–20 dB) threshold shifts occurred when tones preceded or followed the masker by 10 and 30 msec; at 100 msec, masking was negligible in most subjects. On the discrimination task, there was evidence of temporal masking 200 msec before the F1 onset and after the F1 offset. The data suggest that shifts in detection threshold account for only a part of the temporal masking that reduces discrimination of speech-sound information.
Masking of filtered noise bursts by synthetic vowels
Authors: Weiss M. S. , Resnick S. B. , Heinz J. M.
Published: October 2005

The present investigation was designed to study temporal-masking effects produced by speech-like signals. The masking stimuli were computer-generated vowel-like signals; two durations (100 and 200 msec) of each of four vowel-like signals were employed. The probe stimuli were three filtered noise bursts which differed in their spectral distribution. A noise burst preceded, followed, or occurred simultaneously with a vowel-like signal. The maximum interstimulus interval was 100 msec. Masked thresholds were determined for four well-trained subjects using the method of adjustment. The results were generally in accord with the findings of temporal-masking studies in which nonspeech-like stimuli were employed. The effects of the duration and spectral characteristics of the vowel-like signals on detectability of the noise bursts are discussed. [Research supported by NINDS.]
Two processes in vowel recognition: inferences from studies of backward masking
Authors: Dorman M. F. , Kewley-Port D. , Brady S. , Turvey M. T.
Published: October 2005

The recognition of brief vowels was studied in forward- and backward-masking paradigms. In a series of experiments in which both target and mask parameters were systematically varied, two populations of subjects were consistently identified. The majority (nonmaskers) evidenced no masking at any interstimulus interval (ISI) while relatively fewer subjects (maskers) evidenced backward masking (but not forward masking) out to 100–200 msec ISI. Increasing target set size systematically increased the extent of masking for the maskers. Adding −15-dB white noise relative to the vowel amplitude increased the extent of masking for both groups. These results suggest two parallel recognition routines for vowels, at least one of which may involve a serial search process.
Normal-mode analysis of underwater-sound propagation with directional sources and receivers
Authors: Williams A. O. , Novak Bruce M.
Published: October 2005

Standard normal-mode analysis of underwater-sound propagation assumes only an omnidirectional point source. Other writers have proposed that, for use in calculations, a virtual line-array of discrete point sources, arranged vertically, can well approximate the directivity pattern, in the vertical plane, of actual sources. It seems better, however, to use an equivalent vertical line array with a continuous distribution of strength and phase. The equations for relating the actual source and the line source are given, and their solution is discussed. Identical methods allow the calculation of reception by a directional receiver. A related topic, use of a vertical array of discrete elements to stimulate or receive a single mode, is also discussed. An illustrative directivity pattern is presented, for an array adjusted to select the first mode in a shallow-water problem.
Detectability of interaural delay in high-frequency complex waveforms
Authors: Henning G. Bruce
Published: October 2005

Observers can detect interaural delays in three component stimuli produced by sinusoidally modulating the amplitude of a sinusoidal carrier. Interaural delays are detected in stimuli confined to a high-frequency region even in the presence of an intense, low-pass filtered noise. With 300-Hz modulation of a 3900-Hz carrier, detection of interaural delay is equally good when either the entire stimulus or just the envelope of the stimulus is delayed. In either case performance is as good as with a 300-Hz pure tone.
Fluctuating forces appropriate for the calculation of discrete frequency noise generation in subsonic turbomachines
Authors: Fleeter Sanford
Published: October 2005

Discrete frequency noise generation at blade-passage frequency and its harmonics is a result of the aerodynamic interaction between successive rotors and stators. These interactions result in fluctuating forces on the rotor and stator blades which are equivalent to dipole sources radiating sound. This paper describes the importance of including airfoil cascade parameters and compressibility, even at low Mach numbers, in calculations of these fluctuating forces. The results are based upon solutions to the unsteady, compressible, two-dimensional partial differential equation which describe the flow disturbances generated by upstream obstructions being convected downstream past an airfoil cascade. The parameters include the cascade stagger angle, cascade solidity, reduced frequency, and the ratio of the number of upstream obstructions to downstream airfoils. The results indicate that isolated airfoil aerodynamics does not adequately describe these fluctuating forces; incompressible cascade aerodynamics is not adequate in the neighborhood of the resonance Mach number, but may be adequate at Mach number values both higher and lower than the neighborhood of the resonance Mach number. The extent of the neighborhood of this aerodynamic resonance wherein compressibility and cascade effects are important, is a function of the flow and cascade parameters.
Effect of listening interval on auditory detection performance
Authors: Goodenough David J. , Metz Charles E.
Published: October 2005

A model based upon fundamental principles of signal detection theory has been developed that quantitatively predicts the decrease in auditory detection performance corresponding to an increase in the listening interval during which a signal of fixed duration may be presented. The model also provides a possible explanation for the commonly encountered asymmetry of experimental receiver operating characteristic (ROC) curves, which has been attributed previously to different variances of noise and signal-plus-noise probability distributions.
Electrical potentials and fluid boundaries within the organ of Corti
Authors: Lawrence Merle , Nuttall Alfred L. , Clapper Maxine P.
Published: October 2005

With careful preservation of the capillary blood supply and by direct visualization of the cells and spaces of the organ of Corti, electrolyte-filled glass micro-electrodes are passed through the structures while the following are recorded: the dc resting potentials, ac potentials generated in response to a 200-Hz microvibrator vibrating either the stapes or basilar membrane directly, and tissue-electrode impedance at 250 Hz. The electrode paths are verified visually followed by surface preparation and scanning electronmicroscopy. So far, electrophoretically injected dyes have been too diffuse to be useful for this purpose. It is observed that the fluid spaces of the organ of Corti, including the subtectorial space and inner sulcus, are at, or only slightly more negative than, the potential of the scala tympani perilymph and that all of the observed large negative potentials are intracellular. The tectorial membrane also is at the same potential as the organ of Corti spaces and the perilymph. The membrane is easily dislodged from its attachment allowing endolymph to cover the hair cells and fill the internal sulcus. When the stapes is vibrated at 200 Hz the vibration of the basilar membrane is such that the generated ac potentials are radiated from the organ of Corti in the apical region of the cochlea and are recorded maximally in the endolymph of the scala media by the micro-electrode in the basal hook region. When the basilar membrane is vibrated at 200 Hz in the region of electrode placement, the electrode records the largest ac response at the basilar membrane and at the tectorial membrane-endolymph and at the Claudius' cell-endolymph interfaces. Impedance measures made simultaneously with the ac and dc measures indicate that the regions of different potentials observed are not the results of changing tissue-electrode impedance. A unique observation is that there is a marked impedance increase as the electrode passes through the area of Claudius' cells. Boettcher's cells may be responsible.
Psychophysical verification of predicted interaural differences in localizing distant sound sources
Authors: Molino John A.
Published: October 2005

Subjects made forced choices to either side of a reference direction (0°, 30°, 60°, and 75°) to locate the image of pure tones presented through earphones. Various combinations of interaural intensity differences (IID's) and interaural time differences (ITD's) were used, including some combinations which do not occur in nature. Psychometric functions confirmed the expected apparent azimuth of ITD/IID combinations based on free-field diffraction theory and microphone measurements. The relative dominance of the intensive and temporal cues was examined at each frequency (500, 1000, and 8000 Hz). The shape of the psychometric plane for the bidimensional matrix at the 1000-Hz 30° condition showed possible nonlinearities in the trading relation. Data were also collected from the same subjects using the same signals presented by means of distant loudspeakers in an open field. When the free-field data were compared with the data from earphone-simulated sounds, they showed similar angular acuities, being approximately the size of those reported in the literature. Key Words: Auditory localization, diffraction patterns; earphone simulation; human audition; interaural differences; minimum audible angle; psychometric functions; psychophysics; space perception.
Influence of deviations and variations in transducers on the filtering actions of spectral filters
Authors: Maidanik G.
Published: October 2005

The filtering action of a spectral filter changes when the filtering functions of the transducers, of which it is composed, change. Practical transducers possess filtering functions that exhibit inherent deviations from the nominal forms that are assigned to them. This paper presents an assessment of the influence that such deviations have on the filtering action of a spectral filter. Of particular interest are deviations that have statistical distributions so that ensemble average of the filtering action can be defined and estimated. Also assessed in the paper is the influence of variations in the filtering functions of the transducers on the filtering action of a spectral filter. Variations are the changes that are introduced by design. Of particular interest are statistical variations in the positions of the centers of the transducers. It is argued that such variations may, in certain cases, be advantageous. Numerical examples that illustrate the analytical formalism are cited.
Tabulation of some integral functions describing diffraction effects in the ultrasonic field of a circular piston source
Authors: Benson G. C. , Kiyohara Osamu
Published: October 2005

Values of some integrals occuring in the theory of diffraction effects were computed and used to calculate the average phase and average relative amplitude of the acoustic pressure experienced by a circular receiver coaxial with a circular piston transducer of the same radius. Tables of the results are described.
Angular dependence of spectral shapes of near-surface fired charges
Authors: Bluy O. Z. , Payne F. A.
Published: October 2005

Two experiments were performed to determine the directional characteristics of explosive charges fired near the surface, one at close range, and the other at long range. The results are presented as source spectra for various measurement angles, and indicate a frequency-dependent source directivity.
SOFAR accuracy in the North Pacific
Authors: Northrop John
Published: October 2005

SOFAR fixes were obtained by a computer program on a number of underwater explosions and implosions of various sizes and depths off the coast of California. Results are: (1) Accuracy of SOFAR fixes was best for events detonated in the sound channel; (2) SOFAR fixes on the implosions were within one standard deviation of those for explosions at the same depth; (3) SOFAR accuracy, compared to delivery vehicle navigation, was better for events dropped by ships than for those dropped from aircraft; and (4) SOFAR accuracy improved when a larger number of detection hydrophones was used in obtaining the fix.
Effect of cylindrical scatterers on the radiation resistance of a transducer at an air-water surface
Authors: Stumpf F. B. , Sugar R. J.
Published: October 2005

The radiation resistance of a small magnetostrictive transducer at an air-water surface has been measured with a small hard or soft cylinder placed nearby in the water. Different orientations and sizes of the cylinders were used. The cylinder has strong effects on the transducer's radiation resistance when placed within two or three wavelengths and might be useful as a device for controlling the radiation impedance. This effect may also have possibilities for the detection of flaws.
Some Aspects of Acoustic Shock Emission of High-Speed Nozzles
Authors: Peter Abraham C.
Published: October 2005

The problem of acoustic shock emission of high-speed nozzles is discussed in terms of the theoretical aspects of nonisentropic wave generation. [J. Acoust. Soc. Amer. 45, 339(A) (1968)]. Some of the recent developments in the analytical and computational aspects of the problem are presented with emphasis upon exhaust shocks of conical structure. Initial efforts to isolate the mechanism of shock emission in terms of nonisentropic sources indicate that local velocity fluctuation are of second-order magnitude and serve as a triggering device rather than as actual acoustic flow sources. In effect, the mathematical model indicates that shock-wave emission predominates in the mechanism of high-speed exhaust noise. [This study is supported by the Unsteady Aerodynamics Branch of the National Aeronautics and Space Administration in Huntsville, Alabama.]
Long-Range Acoustic Signals from the SATURN I in Flight
Authors: Fehr U. , Kaschak George
Published: October 2005

The APOLLO VII launch from Cape Kennedy produced several types of long-range acoustic signals. At a station 1500 km away, the first arrival signal was traveling at almost five times the speed of sound. A second supersonic signal had a group velocity more than twice the sound speed. A third signal, coming from the ballistic wave of the re-entry of the first stage, had normal speed and its azimuth pointed to the trajectory of the re-entry vehicle. A fourth signal produced by the rocket's exhaust and ballistic wave while ascending through the atmosphere arrived as the last signal at normal sound velocity. The durations of the supersonic signals are 2 min each, while the normal signals are about 7 min each. Signal amplitudes peak in the order of 10 dyn/cm2. The frequency bandwidths of the supersonic signals are narrow (2–4 Hz), while the normal are wide band. The supersonic propagation is described as a coupling mode through an adjacent medium.
Model Experiment on Variability of Sonic-Boom Signatures
Authors: Davy Bruce A. , Blackstock David T.
Published: October 2005

Sonic-boom signatures observed at the ground frequently differ markedly from the ideal N shape predicted by simple theory. Prominent among the observed variations are “peaked-N” and “rounded-N” waveforms. A. D. Pierce [J. Acoust. Soc. Amer. 44, 1052–1061 (1968)] has recently proposed an explanation based on a combination of refraction and diffraction by atmospheric irregularities. An irregularity has the net effect of an acoustic lens. A diverging lens produces the “rounded-N” waveform; a converging lens, the “peaked-N” waveform. In our model experiment, which was done in air, N waves of about 25-μsec duration were generated by an electric spark and received by a very-wide-range condenser microphone (rise time about 1 μsec). A gas-filled soap bubble served as the acoustic lens. It was found that a helium-filled bubble (diverging lens) produced rounding of the N wave. An argon-filled bubble (converging lens) caused peaking. Thus Pierce's model was substantiated. [Work supported by the Mechanics Division, AFOSR, OAR.]
Studying Children's Acquisition of Phonology
Authors: Menyuk Paula
Published: October 2005

Most children by age 4 are communicating effectively with sentences that contain all the basic syntactic structures in the language. It, therefore, would seem reasonable to suppose that the phonological features and rules of the language are acquired at an early age as well. We have, however, very little information about either the actual facts of this acquisition and development or the psychomotor mechanisms that underlie the process. Several studies have been undertaken to examine the child's use of the suprasegmental, segmental, and sequential features of the sound system of his language at various stages of development. The results of these studies and some previous research will be discussed in terms of various models of phonological acquisition and use. [Work supported by National Institutes of Health grant.]
Two-Dimensional Sampling in Acoustics
Authors: Tripathi I. D.
Published: October 2005

The importance of acoustics as a vehicle of transmission of information about certain characteristics of a surface is increasing with our increasing curiosity about the inner space. This is much more appreciated in the situations where neither optics nor electromagnetic radiation in microwave region is of much help. The concepts of Fourier analysis and synthesis have played a very dominant rôle in advancing electrical communication. It is desirable that possible application of these concepts in the area of acoustics be looked into. Acoustic pressure over a plane surface is a function of two dimensions. Intuitively, it is apparent that if we sample the pressure closely enough over the surface, the entire pressure distribution can be obtained with considerable accuracy by simple interpolation. For a band-limited function in one dimension, if the maximum interval of sampling is the Niquist interval, the function can be reconstructed exactly. A similar criterion is extended for a class of pressure variations over a surface whose two-dimensional Fourier transforms are nonzero over only a finite region. The sampling criterion is obtained by using the properties of two-dimensional Fourier transformation and sampling property of two-dimensional delta function.
Representation and Analysis of Time-Limited Data Samples Using a Complex Exponential Algorithm
Authors: Quazi Azizul H. , Spitznogle Frank R.
Published: October 2005

A complex exponential algorithm developed for the representation and analysis of time-limited signals is defined, and its evaluation with respect to conventional discrete Fourier techniques is discussed. It is shown that for a given length of a signal containing discrete frequency information, sampled at least to the Nyquist criterion, the complex exponential algorithm can often provide increased frequency resolution over standard Fourier techniques. It will also be shown that the complex exponential algorithm provides an improved mechanism over Fourier techniques for interpolation between points in a sampled signal containing discrete frequency components in the presence of broad-band noise. The effects of noise on the complex exponential technique and the computational difficulties associated with the present complex exponential algorithm will be discussed. At the present time, the major difficulty associated with the complex exponential technique is that the algorithm requires more computational time than the fast Fourier transform.
Adaptive Unsupervised Detection with Finite Memory
Authors: Spooner Ronald L.
Published: October 2005

Techniques used in the area of pattern recognition, particularly the methods of unsupervised learning, are beginning to appear useful in the area of analyzing underwater acoustic signal spectra. A problem encountered in the use of these techniques for varied situations is that of an unlimited memory requirement when uncertain parameters are present in either the signal or noise process. The problem considered here is the design of a limited-memory receiver for the unsupervised detection of signals in noise. Limited memory is achieved using quantization of a sufficient statistic, and the optimum-likelihood receiver is developed under this constraint. The limited-memory receiver is shown to retain adaptive or learning characteristics, and its performance is shown to converge to that of the unlimited-memory receiver with increasing time. The primary intent of this work indicates the effect of increasing memory—in other words, increasingly finer quantization—on the performance of the limited-memory receiver and compares this with the performance of the unlimited-memory receiver.
Bearing and Range Estimation with a Linear Passive Sonar Array
Authors: Lewis J. B. , Schultheiss P. M.
Published: October 2005

This paper considers the ability of the optimum passive detector to locate a point target in bearing and range. Signal and noise are assumed to be stationary Gaussian processes. For low input signal-to-noise ratio, it is possible to define convenient measures of bearing and range accuracy, whose dependence on such parameters as input signal-to-noise ratio, observation time, and processing bandwidth can then be studied. One finds that the most important contribution is made by the highest frequencies. When one uses the same criteria to describe the target-locating ability of a conventional detector, one finds that maximum detector output may occur for an indicated position that does not coincide with the true target position. This systematic error increases as the input signal-to-noise ratio decreases. [Work supported by Office of Naval Research through prime contract with General Dynamics/Electric Boat under the SUBIC program.]
Deposition of Piezoelectric Cadmium Sulfide Films from a Single Source of Cadmium and Sulfur Vapor
Authors: Beecham D.
Published: October 2005

This paper describes a simple method of depositing from a single source films of CdS with reproducible properties. These films are highly oriented and highly resistive so that they function effectively as piezoelectric transducers. The CdS is grown on a heated substrate from Cd and S vapor produced from a source utilizing a single heater. To equalize the rates of evaporation, the S is sealed in a vessel with a small exit orifice. A major advantage of the single heater source is that variations in heat input to the source during the evaporation period have little effect on the ratio of the vapor pressures, and therefore the stoichiometry remains constant. Films of CdS up to 6 μ thick with resistivities of 1010 Ω cm have been grown. The films are piezoelectrically active with coupling constants of about 0.12. They can be grown to generate predominantly either the shear or longitudinal mode of vibration. In either case, the unwanted mode is better than 48 dB down from the wanted mode. The method has a high yield rate of good films.
Surface Wave Propagation on Piezoelectric Materials
Authors: Daniel M. R.
Published: October 2005

Surface waves (Rayleigh and Love) are the normal propagating modes of vibration on a free surface. Propagation on anisotropic piezoelectric materials can only occur along certain crystallographic directions for which the piezoelectric matrix gives a direct method of determining the principal ones. Surface waves been generated on nonpiezoelectric Al2O3 by depositing thin films of piezoelectric ZNS or CdS. Some discussion is given of the practical arrangement of electrodes for generating surface waves with reference to frequency response. Evidence has been accumulated to suggest that in quartz, for instance, bulk shear and compressional waves are always generated in addition to the surface wave. This is one factor limiting the ultimate conversion efficiency of electrical energy to surface sound energy. Conversion efficiencies of 100% or greater are achievable in semiconducting piezoelectric materials under conditions of acoustic amplification. Results are presented of attenuation measurements of Rayleigh waves in quartz to demonstrate a general T4 phonon-phonon type of scattering present at low temperatures. The application of surface waves in electronic signal processing is illustrated by way of a delay line, directional coupler, and waveguide.
Intracochlear Responses to Tones
Authors: Weiss T. F. , Peake W. T. , Sohmer H. S.
Published: October 2005

We have recorded intracochlear potentials in response to tones by means of glass microelectrodes inserted through the round window (reference electrode on cat's chin). The data indicate: (1) There are large changes in the magnitude and phase of cochlear potentials across the basilar-tectorial membrane complex; (a) the phase of the cochlear potential in scala media leads that in scala tympani by a function approaching 0° at low frequencies and increasing to 180° at high frequencies, (b) the magnitude of the cochlear potential in scala media exceeds that in scala tympani by as much as 20 dB at low frequencies, and becomes smaller at higher frequencies. (2) Relatively small changes in cochlear potential are obtained throughout a traverse of the scalae and across Reissner's membrane. [Supported by the NIH and the Joint Services Electronics Program.]
Vibration Transmission in a Ribbed Cylindrical Shell
Authors: Manning Jerome E.
Published: October 2005

An experimental and theoretical study of the high-frequency vibration transmission in a ribbed cylindrical shell is presented. Emphasis of the study is on the variation of the vibration level from point to point on the shell when the shell is driven at one or more points. Experimentally observed variations of the vibration level within each subpanel and of the subpanel-average levels in the shell are presented. The experimentally observed variations are compared with theoretical predictions. Analogies between this vibration problem and the problem of sound-pressure level variations in a reverberation chamber are made. The rôle of parameters such as damping, frequency, bandwidth of excitation, modal density, and number of excitation points is investigated. [The research reported in this paper was supported by the National Aeronautics and Space Administration under contract.]
Turbulence-Induced Plate Vibrations: A Comparison of Finite and Infinite Plate Models
Authors: Strawderman Wayne A.
Published: October 2005

Turbulent-flow-excited plate-vibration statistics are computed for mathematical models of finite and infinite thin plates. The computed statistics for the finite and infinite models are compared to establish similarities and differences between the vibration statistics for the two models. The computed statistics are also compared with available experimental data to determine which model better approximates reality. These comparisons show little similarity between computed vibration statistics for the infinite and finite models. Plate vibration statistics computed from the finite plate model are in substantially better agreement with available experimental results than those computed from the infinite model.