bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency Difference Limen Using Frequency-Modulated Tones
Authors: Feth Lawrence L. , Wolf Richard V.
Published: September 2005

Since the classical work by Shower and Biddulph, the use of frequency-modulated tones in the determination of the difference limen for frequency has been based upon an intuitive approach to spectrum analysis. The resulting intuitive spectrum is simply the amplitude distribution of the modulation waveform, projected into the frequency domain. Inherent nonlinearities in the frequency modulation process often cause the true spectrum to differ drastically from the intuitive spectrum. Using a new tracking system for determining the frequency DL, we attempted a partial replication of the Shower and Biddulph experiment. However, like several other experimenters, we obtained larger DL's than those reported by Shower and Biddulph. Considering the various modulation waveforms and rates used, we reconcile these different results using true spectra rather than intuitively derived ones. [This research was supported by research grants from the National Institute of Neurological Diseases and Blindness, U. S. Public Health Service.]
Pitch of Frequency-Modulated Signals
Authors: McClelland Keener D. , Brandt John F.
Published: September 2005

The pitch elicited by 300-, 1000-, and 3000-Hz sinusoids frequency modulated by 20-, 200-, and 2000-Hz sinusoids (the latter for the 3000-Hz carrier frequency only) was investigated at 20 and 50 dB SL. The frequency deviation of the carrier frequency was ±100 Hz for all stimulus conditions. Five normal-hearing listeners matched unmodulated sinusoids in a free-response task to any and all “pitches” perceived in the FM signals. Pitch matches occurred to individual spectral components when the component frequency spacing exceeded critical bandwidth. When component spacing was less than critical bandwidth pitch matches occurred randomly within the energy band, at the center of the energy band, or at the ends of the energy band. No pitch matches were made in response to anything but spectral-energy information.
Degradation of Detectability of Passive Signals Due to Surface Scattering
Authors: McDonald John F.
Published: September 2005

Loss of detectability in wide-band passive detection systems due to ocean surface scattering can be significant. Evaluation of this loss and design of optimum detection systems is complicated by the fact that the scattered signal generally has non-Gaussian statistics even when the transmitted signal is Gaussian. The output signal-to-noise ratio for certain correlator detectors is examined for one- and two-element receivers and simple rectilinear propagation geometries. A variation of the scattering model proposed by Gulin [Sov. Phys.—Acoust. 8 (1963)] is applied to the computation of scatter degradation using moment methods. This model consists essentially of a sinusoidally shaped boundary moving at a slowly varying rate and varying slowly in amplitude. Results are compared with those obtained for a simpler model depicting the scattering as a random attenuation and delay. Fourth-order cumulants for the scattered signals are examined, and sixth order moments are shown to be important when delay modulation due to scattering becomes significant. [Work supported by Office of Naval Research through prime contract with General Dynamics/Electric Boat under the SUBIC program.]
Optimum Passive Bearing Estimation
Authors: McDonald V. H. , Schultheiss P. M.
Published: September 2005

This paper studies the minimum bearing error attainable with a linear passive array. Signal and noise are stationary Gaussian processes with arbitrary power spectra, and the noise is assumed to be statistically independent from hydrophone to hydrophone. The Cramer-Rao technique is used to set a lower bound on the rms hearing error and the results are compared with the bearing error of a slightly modified split beam tracker. The latter reaches the lower bound for a two-element array and comes very close to reaching it for a linear array with an arbitrary number of equally spaced hydrophones. Thus, the modified split beam tracker is very nearly optimal. The dependence of the rms error on signal-to-noise ratio is the same for the split beam tracker and for the Cramer-Rao lower bound. Parts of the results are extended to arrays operating in a noise field containing a directional component. [Work supported by Office of Naval Research through prime contract with General Dynamics/Electric Boat under the SUBIC program.]
Design Parameters of Free-Flooding Cylindrical Transducers
Authors: Junger M. C.
Published: September 2005

Theoretical results evolved by Yen, Duncan, and Copley for radially vibrating “squirters” provide the basis for a systematic design procedure. The bandwidth is controlled by the ratio of natural frequency fn of the submerged transducer to frequency of maximum radiation resistance fr. Design flexibility results from the dependence of this frequency ratio on the ratio of transducer length, 2L, to radius a. fr decreases monotonically with increasing L/a. Radiation reactance causes fn to drop with increasing L from its in vacuo value to a minimum. For large L/a, fn becomes indepndent of L/a. For transducers with in vacuo natural frequencies ka≈2, fn rises above its in vacuo value for L>2a/3. In this L/a range, one ratio L/a may display several natural frequencies associated with different pressure fields. This analytical formulation is applicable to arrays of axially spaced, coaxial, free-flooding, or solid cylinders. It can account for parasitic nonaxisymmetric modes. [Performed under contract with Office of Naval Research (Acoustics Programs).]
Human Factors in Wind-Instrument Performance
Authors: Bouhuys Arend
Published: September 2005

To the physiologist, wind-instrument performance is a prime example of a skill that requires precise coordination and control of the contractions of several groups of striated muscles. Respiratory muscles, together with elastic forces in lungs and chest wall, provide the required pressurized stream of air. Oral cavity and lip muscles provide adequate shape and tension of the lips for proper excitation of reeds. They also direct and shape the air-flow pattern in flutes. Lastly, forearm muscles control finger movements. The lip vibrations in brass players occur at frequencies higher than those at which striated muscles can contract; these vibrations are passive, but muscle contraction largely determines the physical characteristics of the oscillating lips. Rapid and precisely quantified changes in muscle contractions are needed to alter this adjustment for production of tones of different pitch and amplitude. Coordination and control of striated muscle will be discussed, using the respiratory muscles as the main example. Relevant physiological knowledge will be reviewed; however, large gaps exist in the understanding of skilled movements and the learning processes involved in acquiring such skills.
Practical Design of Brass Wind Instruments
Authors: McCracken George
Published: September 2005

This presentation will discuss the practical application of acoustics in the design of brass wind instruments from the point of view of the manufacturer and will deal specifically with certain recent designs by the author. The discussion will explain how design parameters are determined and met by the designer and how the design is expressed practically by the manufacturer. Various methods of metal forming used in the manufacturing of the important acoustical elements will be explained and illustrated. Several newly designed instruments will be shown, discussed, and demonstrated.
Evaluation of Acoustical Adjusting Devices Using a 1-to-24 Scale Model of an Auditorium
Authors: Marshall L. G. , Watters B. G. , Bentivegna P. I. , Johnson R. , Kirkegaard R. L.
Published: September 2005

It has been recognized for many years that varying types of performance activities in multipurpose auditoriums require substantial adjustment in the acoustics environment if optimum hearing conditions are desired. This paper discusses use of a 1-to-24 scale model of an auditorium to help evaluate the acoustical effectiveness of motor-operated adjustment devices. The tests used an impulse-noise source at various locations on stage and a microphone positioned in various seat locations. The decay fields established by various combinations of source/receiver positions were displayed on an oscilloscope, and photographed. The photos were compared to study the changes in the decay field resulting from adjustments of the model reflecting and absorbing surfaces. The results of this testing program are described.
Effect of Attention on Auditory Evoked Potentials in Cats
Authors: Oatman Lynn C.
Published: September 2005

Click-evoked potentials were recorded from unanesthetized cats with electrodes chronically implanted in the auditory cortex, cochlear nucleus, and round window. The clicks (irrelevant stimuli) were presented continuously as background before, during, and after the presentation of a visual discrimination task (relevant stimuli) which attempted to alter the attentive state of the animals. The mean peak-to-peak amplitudes of averaged click-evoked responses from six adult female cats were significantly smaller during attention to the visual discrimination stimuli when compared with the prediscrimination and control periods. This relationship was present at all electrode placements for five experimental animals with middle ear muscles cut as well as one control animal with middle ear muscles intact. The results suggest that during attention, a central inhibitory mechanism, independent of middle ear muscles, modifies click evoked responses possibly via the olivocochlear bundle, which terminates on the hair cells in the cochlea.
Ultrasonic Vocal Output in CBA/J Infants and Their Effect on Adult Laboratory Mice
Authors: Berlin Charles I. , Majeau Deborah , Soileau P. S. , Palestrant M. , Steiner Sylvia
Published: September 2005

Our attempts to attract mothers of CBA/J mice with real or synthetic ultrasonic infant distress cries have been unsuccessful. We synthesized cries in the 50- to 70-kHz range, and also used recordings of high-pass filtered true cries, but neither mature male nor female mice, nor even recently parous female mice, were systematically attracted to this signal. We subsequently discovered that our CBA/J mice, despite their widespread use as laboratory animals with “normal” hearing, have late degeneration of hair cells at the basal turn. Evoked cortical potentials at high intensities showed little responsiness above 50 000 cycles in nine-month-old animals. Surface preparations of the organ of Corti show normal hair cells at four weeks, but serious deterioration is seen in the hair cells of the basal turn by nine months. This may be a recent (perhaps mutational) occurrence in the CBA/J strain because vertical sections of the organ of Corti (Guild's method), have shown no such degeneration in reports of others. [Work supported by the National Institute for Neurological Diseases and Blindness.]
Sonic Sensitivity of the Blind Cave Fish (Anoptichthys Jordani)
Authors: Weiss Burton A.
Published: September 2005

Sonic sensitivity of blind cave fish having only vestigial eyes indicates that the lateral line is more sensitive than the same sense in other fishes. Blind cave fish appear to be employing the lateral line to detect the displacement waves from their own swimming motion when reflected by nearby objects in order to avoid obstacles. [Research supported by NINDB and ONR.]
Ambiguity Function for Wide- and Narrow-Band Signals with the Effect of the Acclerating Point Target
Authors: Lee S. P.
Published: September 2005

Conventional ambiguity-function theory is applied when estimates of range and Doppler for moving targets are desired. Unfortunately, previously available literature has not considered the effects of an accelerating target. This paper is extended herein for both linear FM and pulsed CW signals to account for these effects, and the resulting half-power contours are plotted. For the linear FM pulse, the matched contours lengthen with acceleration, if mismatched in both Doppler and acceleration, the ambiguity function assumes the form of an Airy function, and representative contours for these conditions are also given. For the pulsed CW, the ambiguity function assumes a form that includes Fresnel integral; the resulting half-power contours are rotated when accleration is allowed in matched situations. When there is mismatch, the contours are both translated and rotated.
Signal-to-Noise Ratio in Amplitude Quantizers
Authors: Hariharan P. R.
Published: September 2005

A general analysis is made of the relationship between the output signal and noise powers and input signal and noise powers for a 2N-step, symmetric amplitude quantizer. The input to the quantizer is assumed to consist of a sinusoidal signal and zero mean Gaussian noise. The method of analysis involves modification of the general transform method for νth-law devices to make it applicable to non-νth-law devices. The resulting integrals are evaluated in two ways. One of these is suited for calculation of (SNR)out for low values of (SNR)in, and the other is especially useful for high (SNR)in. The formulas developed relate (SNR)out to (SNR)in through the characteristics of the quantizer.
Study of Liquid Dynamics by Neutron Scattering
Authors: Schofield P.
Published: September 2005

This paper reviews the information about the collective motions of atoms in liquids which can be obtained from neutron scattering experiments, with particular attention to the rare gases and liquid metals. The current status of the theoretical interpretation is examined. Coherent neutron scattering from a monatomic liquid gives directly the spectrum of the correlation function for density fluctuations in the system for wavelengths in the range 1–10 Å. The results have a dual interpretation. On the one hand, they may be understood in terms of a viscoelastic theory, which takes into account the microscopic structure of the liquid; on the other hand, fluctuations at these wavelengths may be interpreted in terms of vibrational modes, as in an amorphous solid. The paper attempts to reconcile these two points of view. Qualitative differences between liquid argon and the liquid metals are discussed with reference to the connection between the neutron results and the microscopic properties of these liquids.
Time-Domain Measurements of Cochlear Nonlinearities Using Combination Click Stimuli
Authors: Pfeiffer Russell R. , Goblick Thomas J.
Published: September 2005

Spike discharge patterns of single cochlear nerve fibers in response to acoustic clicks imply that the cochlear neuron is excited by an oscillatory waveform—termed a Click Excitation Function (CEF)—presumably related to the impulse response of the basilar membrane. For a given fiber, the intensities of two clicks separated by k half-periods of the fiber's characteristic frequency can be adjusted so that a particular peak does not appear in the poststimulus time histograms to both polarities of the stimulus. If each click is assumed to produce identical, linearly superposing CEF's, then the relative amplitudes of adjacent peaks of the CEF can be determined by this nulling technique when k=1. To test this assumption, the relative amplitudes of peaks separated by k half-periods can be obtained either indirectly from k=1 measurements or by direct measurement with click separations of k > 1 half-periods. The results obtained by these two methods do not agree and, hence, are inconsistent with the linear superposition of CEF's. This deviation from linearity (from a few decibels to more than 30 dB) increases with separation between the two clicks (0.3 to 4 msec) but is independent of the refractoriness associated with neuron discharge. This temporal nonlinear phenomenon provides new constraints on nonlinear mechanisms employed in models of the peripheral auditory system. [This investigation was supported by PHS research grants from the National Institutes of Health.]
Temperature Dependence of Low-Frequency Sound Attenuation in Fresh and Sea Water
Authors: Jones Everett N. , Browning David G. , Thorp William H. , Mellen Robert H.
Published: September 2005

Low-frequency sound-absorption measurements in both fresh and sea water show anomalous behavior that is consistent with a relaxation process near 1 kHz. Furthermore, comparison of the 4°C measurements in the Atlantic Ocean and Lake Superior with the 13° Mediterranean Sea values indicate an increase in relaxation frequency with temperature corresponding to an activation energy of almost 10 kcal/mole. Further experiments are planned in Lake Tanganyika and the Red Sea (23°C) to test the hypothesis.
Some Thoughts on the Stochastic Born Series for Sound Propagation in the Ocean
Authors: Bugnolo Dimitri S.
Published: September 2005

The propagation of acoustic waves in the ocean may be of some importance in the study of medium stability. Stochastic fluctuations in the sound-velocity profile may be produced by perturbations in temperature, salinity, or “static” pressure. This paper is devoted to a review of the theoretical procedures that, in the past, have been limited to first Born approximations as well as approximations for the Green's functions. A solution is presented for the complete Born series for the expectation of the potential function.
Normal Mode Solution for a Bilinear Profile with Fluid-Type Bottom
Authors: Bartberger C. L. , Ackler L. L.
Published: September 2005

A computer program has been written for a normal-mode solution of the wave equation in a medium consisting of two layers, in each of which the reciprocal of the square of the sound speed is a linear function of depth. All possible combinations of algebraic signs are permitted for the gradients in the two layers. A flat, homogeneous, nonelastic, attenuating bottom is assumed. The solution is programmed as a sum of normal modes, the depth functions being expressed in terms of Airy functions. The eigenvalues are computed by an iteration process in the complex plane, employed by Pedersen and Gordon [J. Acoust. Soc. Amer. 37, 105–118 (1965)], the initial estimates being obtained by a WKB approximation, combined with an application of ray theory. The branch line integral, which makes a significant contribution only at relatively short ranges, is neglected. The program has the capacity of computing up to 190 modes and is used for shallow-water propagation and low-frequency convergence zone propagation.
Effects of an Undulating Bottom on the Propagation of Sound in Shallow Water
Authors: Kamenyitzky A. J.
Published: September 2005

Experiments are described that show that the transmission loss over various paths in shallow water is highly variable. Known factors that influence the transmission loss are the temperature profile, the bottom type, the water depth, and fish. In this paper, we consider the effect of an undulating bottom. A computer simulation of shallow water sound propagation—using ray theory, empirical bottom reflection coefficients, and random phase shifts to represent the effect of the undulating bottom—indicates that there should be several decibels' variation in the transmission losses over equidistant paths differing slightly in bearing. The rms variation in transmission loss is predicted to increase with range and frequency and decrease with increasing bottom loss. The undulating bottom reduces the “quality” of the waveguide consisting of the surface and bottom and thereby reduces mode structure and reduces the transmission loss caused by phase effects.
Observations of the Fluctuation of Transmitted Sound in Shallow Water
Authors: Urick R. J.
Published: September 2005

An 1120-Hz CW sound source, driven at a constant level, was placed on the bottom in 60 ft of water off Ft. Lauderdale, Florida. Four hydrophones, spaced 10–100 ft apart, were placed on the bottom 4900 ft away, parallel to the depth contours. Both source and hydrophones were cable connected to shore, where recordings were made. Two kinds of fluctuation of the received sound were observed. One kind, with a double amplitude of 5 dB and a period of 3–4 sec, was observed to be related to the prevailing sea and swell. The other kind had a double amplitude of about 15 dB and was associated with the height of the tide. High amplitude occurred at high tide; low amplitude at low tide. This surprisingly large fluctuation, caused by a tidal range of only 2–3 ft, is a mode or ray interference effect explainable by mode or ray theory, and is verified by computer calculations using mode or image attenuations based on a reasonable reflection loss for the coral-sand bottom over which the transmission was taking place.
Experimental Investigation at 60 kHz of the Azimuthal Dependence of Sea Surface Backscattered Sound
Authors: Reeves J. C.
Published: September 2005

The dependence on azimuthal angle of acoustics sea surface reverberation is investigated at 60 kHz with a three-axis rotationally stabilized conical beam transducer. Measurements of backscattering strength in the upwind and crosswind directions are compared for a range of grazing angles from 10° to 40°. Polar plots of scattering strength versus azimuthal angle are presented, and the effect of wind speed on these plots is shown for wind speeds from 4 to 13 kt. An attempt is made to correlate the backscattering measurements with swell and local wind-driven waves by means of aerial sea-state photographs taken during the test. Data indicate that surface reverberation has a pronounced dependence or azimuthal angle at wind speeds below about 9 kt, but becomes indepndent of azimuthal angle at higher wind speeds. For the lower wind speed régime, variations in backscattering strength with azimuthal angle appear to be correlated with swell direction. At higher wind speeds, increased surface disturbance causes the reverberation to increase for all azimuth angles, consequently masking the anisotropic backscatter that prevailed at lower wind speeds.
Acoustic Wave Scattering and Transmission by Corrugated Surfaces
Authors: Barakos Peter A.
Published: September 2005

An exact theoretical model for the interaction between an acoustic plane wave and a stationary internal wave of a two-layer fluid is presented. Weber's two-dimensional analog of Helmholtz's integral formula is employed to represent the scattered and the transmitted acoustic fields. The boundary velocity potentials and their normal derivatives are expanded into complex Fourier series. The complex boundary Fourier coefficients are related by a pair of simultaneous, doubly infinite algebraic equations. Generalized Rayleigh scattering and transmission coefficients are found and exact expressions for the acoustic velocity potentials for the scattered and transmitted fields are given. The principal features of this development are its wide applicability to internal waves of arbitrary amplitude and wavelength and to strongly as well as weakly stratified liquids.
Cinefluorographic Study of Speaking Rate
Authors: MacNeilage Peter F. , De Clerk Joseph L.
Published: September 2005

This study compares the production, at two speaking rates, of 36 consonant vowel-consonant sequences formed by every possible combination of initial and final consonants /b/, /d/, and /g/, and the syllable nuclei /i/, /u/, /æ/, and /ɔ/. Cinefluorograms and sonograms were obtained while one subject spoke the inventory under two conditions. (1) Citation form: The subject read a randomized list of CVC utterances at a normal rate. (2) Fast rate: The subject read the utterances as quickly as was practicable, in subsets of three, embedded in the carried phrase; /se∂ CVC∂se∂ CVC∂se∂ CVC∂se/. At the faster rate, the duration of the CVC components was approximately 40% of that of the citation forms. Comparisons were made between: (1) amounts of coarticulation of adjacent phoneme representations at the two speaking rates; (2) patterns and speeds of articulator movement at the two rates; (3) responses of different articulators to the increase in rate. From these results, an attempt was made to indicate some properties of the mechanism of control of speaking rate.
Digitalized Sound Spectrograph Using FFT and Multiprint Techniques
Authors: Rothauser Ernst , Maiwald Dietrich
Published: September 2005

In the history of speech research, sound spectrographs are playing the rôle of an almost invaluable tool. Besides the many advantages of these instruments, some of their limitations have also become evident. Quite a few of these are a direct consequence of the utilization of analog techniques in these devices. The present paper tries to show that digital-processing techniques allow to implement a spectrographic system much more powerful than its analog counterpart. Its hardware consists of a general-purpose computer adapted to accept digitally encoded speech signals, and a standard chain printer. The short-time power spectra are computed utilizing the fast Fourier transform algorithm. Spectrograms with eight gray levels can be generated by multiprinting adequate sequences of characters out of the basic 48-character set. The necessary computer programs are sufficiently simple to be easily tailored to the specific needs of any particular investigation. Wherever digital processing is used in speech research, the approach described exhibits its greatest advantages. The digital spectrograph can then be seen to constitute an organic part of the total software system being a subroutine that may be called whenever needed.
New Look in Speech Analysis
Authors: Mundie J. Ryland , Moore Thomas J.
Published: September 2005

An electronic model of inner ear function has been employed in the generation of displays of the basilar membrane response to speech inputs. These displays depict displacement as a function of time at 24 locations along the length of the basilar membrane. A very fast (3-megasample/sec), 32-channel multiplexer is utilized to present a quasi-three-dimensional display of this surface on a CRT. This technique shows details in the temporal-spatial surface produced by a speech sound that are not evident in other displays of speech analysis by analog cochlea or more conventional spectrographic techniques. It was found that distinctive features in these surfaces could be used to identify speech sounds reliably.
WINDBAG—A Vocal-Tract Analog Speech Synthesizer
Authors: Baxter Brent , Strong William J.
Published: September 2005

This report describes the beginnings of an effort in speech synthesis at Brigham Young University. Both terminal analog and vocal tract analog synthesizers will be studied eventually, but this paper discusses only a vocal tract synthesizer. The synthesizer is patterned after one described by Flanagan and Landgraf [IEEE Trans. Audio and Electroacoust. Au-16, 57 (1968)] in which the vocal cords and vocal tract are able to interact. A delay-line scheme similar to one described by Kelly and Lochbaum [Proc. Stockholm Speech Commun. Seminar, R.I.T. Stockholm, Sept. 1962)], but terminated at the mouth end with a filter, is used to represent the vocal tract. Some modifications to Flanagan's vocal-cord model have been incorporated. Preliminary synthesis results for steady-state vowels and consonant-vowel transitions will be presented.
Automatic Speaker Recognition Based on Pitch Contours
Authors: Atal B. S.
Published: September 2005

The results of a study aimed at finding the importance of pitch for automatic speaker recognition are presented. Pitch contours were obtained for 60 utterances, each approximately 2-sec in duration, of 10 female speakers. A data-reduction procedure based on the Karhunen-Loeve representation was found effective in representing the pitch information in each contour in a 20-dimensional space. The data were divided into two portions; one part was used to design the speaker recognition system, while the other part was used to test the effectiveness of the design. The 20-dimensional vectors representing the pitch contours of the design set were linearly transformed so that the ratio of interspeaker to intraspeaker variance in the transformed space was maximum. A reference utterance was formed for each speaker by averaging the transformed vectors of that speaker. The test utterance was assigned to the speaker corresponding to the reference utterance with the smallest Euclidean distance in the transformed space. The percentage of correct identifications using the above procedure was found to be 97%. The recognition rate increased to 98% with the addition of duration as an independent measure.
Synthetic Language for Machine Recognition of Speech
Authors: Schanker J. Z.
Published: September 2005

The current state of the art of speech recogntion is such that it appears unlikely that general machine recognition of speech will be accomplished in the near future. In order to accomplish successful speech recognition for purposes of vocal machine control utilizing current technology, a synthetic language for machine recognition is proposed. The phonetic structure of the language is developed after first defining the requirements and showing the potential advantages. Words in the synthetic language are tested with a simple recognition device with promising results.
Regularities of Cross Correlations in Spectra of Speech
Authors: Li K. P. , Hughes G. W.
Published: September 2005

Long-time averages of cross-correlation coefficients of connected speech data derived from filter bank outputs show consistent patterns for a number of talkers. A set of equal-magnitude contours of these coefficients provides a quantitative description and demonstrates the effect of talkers and speech materials. The effect on the contours of including the silent portions of connected speech is evaluated to provide a means of interpreting data previously reported by Kulya. [Experimental investigation of the correlation relations in the speech spectrum and a comparison of some variants of orthogonal vocoder, Telecommunications 18, No. 4, 39–50 (1964).] The cross correlations of individual time samples were examined in an attempt to relate the patterns to the acoustical characteristics of speech signals and to various linguistic concepts. Samples taken from the speech of four male and two female talkers speaking a variety of materials were included in the study. [This work was supported in part by the Air Force Cambridge Research Laboratories.]
Electrical Stimulation of Guinea Pig Cochlea: Effects on Primary Fibers
Authors: Konishi T. , Teas D. C. , Wernick J. S.
Published: September 2005

The effects of dc and ac stimulation, introduced in the basal turn across the organ of Corti [re Tasaki and Fernandez, J. Neurophysiol. (1952)] on the discharges of 144 units recorded with pipet electrodes in the modiolus [Tasaki, J. Neurophysiol. (1954)] were measured during systematic variation of electrical and acoustic parameters. Data, recorded on tape, were analyzed by computing latency and interval histograms. Tasaki and Fernandez [ibid.] reported that V/T polarization (scala vestibuli positive re scala tympani) produced an increase of cochlear microphonic and action potential, while T/V showed a decrease. Our results show that the electric current always altered the discharge rate of primary fibers when their best frequency was greater than 3000 Hz, but the direction of the alteration varied between fibers and depended on the parameters of both acoustic and electric inputs. The rate of spontaneous discharges was also modified but the direction of the change in discharge rate was not always the same as the effect on the evoked discharges. [Partially supported by NIH.]
Cochlear and Neural Auditory Mechanisms in the Raccoon
Authors: Hertzler David R. , Saunders James , Gourevitch George , Herman Paul
Published: September 2005

Electrophysiological measures of sensory and neural auditory responses were recorded in adult raccoons, from which behavioral auditory thresholds had previously been obtained. The characteristics of the peripheral auditory mechanism were evaluated through ac cochlear potential measures of frequency and intensity recorded from the round window. Neural processes were investigated over a range of intensities by measuring the N1 and N2 components of the click evoked potential recorded at the round window. The auditory areas of the cerebral cortex were mapped for click stimuli, and an intensity function was obtained from the most active location. The similarity between the behavioral thresholds and the frequency spectrum of the cochlear potential measures, and, the relationship of the electrophysiological data to that of other mammalian species will be discussed. [This research was supported by NIMH, Public Health Service, and Higgins funds to E.G. Wever, Department of Psychology, Princeton University.]
Evoked Potentials in man in Response to Words
Authors: Derbyshire A. J. , Osenar S. B. , Hamilton L. R. , Joseph M. E.
Published: September 2005

The purpose is to study diffuse EEG responses relative to both the acoustic and informational content of verbal stimuli. Averaging of the EEG is not desirable because the information within a word varies with each individual setting. Two methods are used to replace averaging and enhance the detection of the signal in noise. One is to algebraically sum the EEG patterns simultaneously derived from four or more subjects. This, incidentally, improves the control of the interexperimental variation between subjects. The other is to detect the response by cross correlation of the EEG pattern with a template. The template is described by 6 parameters and represents an analog of the expected diffuse cerebral response. The cross-correlation calculations for a response to a single word result in a correlogram displaying both a maximal value and its time of occurrence. Under our experimental conditions, the characteristics of the sound stimulus are reflected in the time of occurrence of the maximal cross correlation and not in its amplitude.
Motion of Jet in Mouth of Organ Pipe
Authors: Fasnacht W. E.
Published: September 2005

Hot-wire measurements have been made of the position and speed of the air jet in the mouth of a diapason organ pipe. Results indicate the speed of the emerging jet is modulated by the pressure in the pipe, producing an ac component of amplitude approximately 10% of the mean speed. Jet position and shape are in qualitative agreement with the elementary Bechert-Cremer theory. [Work supported by Office of Naval Research.]
Observation of the Motion of the Tongue in a Reed Organ Pipe
Authors: Robbins D. Hurley
Published: September 2005

An 8-ft tuba reed organ pipe was instrumented for the purpose of studying the motion of the tongue. A foil strain gauge was mounted on the tongue to monitor the dynamic bending strain. The strain trace was monitored photographically from an oscilloscope trace. Stroboscopic movies of the tongue motion were taken using the slip-synchronization method. A parametric study of the effect of adjusting the tuning wire was carried out. It was observed both photographically and oscillographically that the tongue actually contacted the reed twice during a short portion of the period of oscillation.
Computer Model of a Clarinet
Authors: Higbee Glen A. , Strong William J.
Published: September 2005

A clarinet mouthpiece and a length of brass tubing were used to construct a “pseudo-clarinet” that sounded at the same frequency as a tone (low G, or concert F) played on a B-fiat clarinet. We further simplified our model for the computer by representing the mouthpiece as an extension of the bore and by assuming plane wave propagation in the tube. The reed is modeled as a one-dimensional oscillator having stiffness, mass, and damping supplied by the lip, and driven by the fluctuating pressure in the mouthpiece. The boundary conditions are: (1) continuity of volume velocity at the reed opening, and (2) a reflected pressure at the open end equal to the negative of the low-pass filtered pressure incident there. Parameters were adjusted so that the calculated values of threshold blowing pressure, mouthpiece pressure, radiated pressure, volume velocity, and reed displacement show reasonable agreement with experimental values of Backus [J. Acoust. Soc. Amer. 35, 305–313 (1963)]. [Work supported by National Science Foundation Undergraduate Research Program.]
Intelligibility and Some Perceptual Confusions of Three Modes of Speaking and Filtering
Authors: Pressman Elaine
Published: September 2005

The purpose of this study was to examine the intelligibility of the consonants of English when presented under three modes of speech and three conditions of filtering. The resulting perceptual confusions were also examined. Twenty-four consonants were acoustically recorded in normal, whispered, and falsetto modes of speech in vowel-consonant-vowel nonsense syllables. These were recorded by five speakers of General American dialect. The stimuli were filtered through three arbitrarily selected bandpass conditions of 2.50–1250, 1250–2500, and 2500–8000 Hz, and then presented for listening to 12 native English speakers who transcribed the consonant they heard. These responses were tallied into a series of nine master matrices and the responses were examined for intelligibility and confusions. For each combination of mode and frequency, the most frequent error responses were determined, together with the correct responses, which yielded approximately 85% of all the responses. A four-factorial analysis of variance was also performed for each one of the consonants. The results indicated that intelligibility varies according to the consonant, the mode of speech, and the condition of filtering. Perceptual confusions varied for a given consonant according to the mode of speech.
Signal Processing for a Cocktail Party Effect
Authors: Mitchell O. M. M. , Ross C. A. , Yates G. H.
Published: September 2005

A binaural listener has the ability to concentrate on speech from a particular location while suppressing speech from other locations (binaural cocktail party effect). Similarly, an array of microphones can be used to achieve an enhancement of intelligibility coming from a particular (on-center) location. This paper discusses various processing schemes for the microphone outputs in order to achieve this discrimination. In particular, one nonlinear process, studied using an analog system employing subtraction, full-wave rectification, and addition, results in reproduction of the on-center speech without change, and in distortion and reduced level of an off-center speech source. Because of the distortion, the suppression appears to be greater than for linear processing. In addition, this process eliminates completely any off-center impulsive noise which is nonoverlapping at the four microphones. It has been pointed out that this process is equivalent to an instantaneous selection of the two microphone outputs which remain when the minimum and maximum outputs are eliminated. A tape illustrating this process for a four-microphone array and two simultaneous talkers will be played.
Optimization of a Prefiltering Technique for the Production of Speech Highly Immune to Noise
Authors: Niederjohn Russell J. , Thomas Ian B.
Published: September 2005

Modification of speech by high-pass filtering and infinite amplitude clipping produces a signal having substantially greater intelligibility than that of normal speech over a wide range of signal-to-noise ratios. The cutoff frequency and attenuation slope of the high-pass filter have been varied to determine the values of these parameters which yield the highest intelligibility. The results of extensive intelligibility tests show that suppression of the first formant prior to clipping is the essential factor contributing to the higher intelligibility of modified speech. At equal signal and noise levels of 90 dB intelligibility scores greater than twice those for normal speech are consistently obtained at a number of filter settings. [Work supported by the National Aeronautics and Space Administration.]
Translational and Rotational Motion of Small Molecules in Liquid Argon
Authors: Ewing George E. , Holleman Gerald W. , Muller Donald E.
Published: September 2005

Far-infrared studies of dilute of H2, HD, D2, and Ne in argon yield considerable information on molecular motion in this liquid system. Rotational absorption features of H2 and D2 between 200 and 1000 cm−1 indicate that these molecules are free rotors in an argon solution. Since HD is an asymmetric molecule, its rotational and translational motions are coupled. The rotational absorptions for HD, therefore, indicate it is not a free rotor. Absorption features are observed that are assigned to translational transitions of Ne, D2, and H2. The spacings of these bands indicates that the translational energy level is in the range of 20–200 cm−1. A simple cell model that treats the solute (Ne, D2, or H2) as an oscillator trapped in a solvent cavity whose walls consist of Ar atoms is in reasonable agreement with the observed spectroscopic transitions. These studies provide evidence for quantized rotational and translational energy levels in this liquid system. In addition, the HD solution illustrates the effect of rotation-translation coupling in the liquid state.
Measurements of Ultrasonic Absorption in Several Liquids in the 1-GHz Region
Authors: Dill J. F. , Mole L. , Derdul P. , Hunter J. L.
Published: September 2005

Measurements of ultrasonic absorption by direct pulse technique have been made in some 15 liquids in the frequency region running from 0.8 to 1 GHz. Some of the liquids used have also been investigated by Plass at 0.4 and 1.5 GHz, and in these liquids, agreement between the two measurements is very good. In general, the measurements confirm the expected values in those liquids that have given previous evidence of relaxation and agree with the low-frequency value in those liquids that have not. [Work sponsored by the Office of Naval Research.]
Ultrasonic Relaxation in a Simple Organic Glass
Authors: Slie W. M.
Published: September 2005

Ultrasonic longitudinal absorption and velocity measurements were made in the glass-forming ionic liquid substance Galex. Galex, a low-molecular-weight wood rosin, is composed largely of dehydroabietic acid. The viscosity of this substance above and below the melting point has an Arrhenius temperature dependence, but the slope of the log η vs 1/T changes near the melting point. The results of ultrasonic measurements on both sides of the viscosity discontinuity indicate the existence of a relaxation region in both the glass and liquid. In both cases, the relaxation process is fully accounted for by a single relaxation time. Analysis of the data shows that in the glass region (low-temperature side of the viscosity discontinuity), structure rearrangement is responsible for the observed excess absorption, while in the liquid region, the relaxation process is thermal in nature.
Damping Definitions and Classifications
Authors: Plunkett Robert
Published: September 2005

Current analysis and nomeclature for damping of mechanical systems depends markedly on the development of the mathematical analysis of dissipative systems over the last century or two. As a result, our current nomenclature is a modification of that appropriate for linear damping, mostly viscous or hysteretic, of single-degree-of-freedom systems. About 40 yr ago, physical chemists and metallurgists started to use the measurement of the attenuation of wave packets to study mechanical properties of solids; their nomeclature reflects this application. Engineers have extended their analysis to slightly nonlinear systems by a quasilinearization approach. Recent conversations between the two groups have led to the proposal of tentative standards based upon the use: of energy dissipation per cycle as a measure either of material or system damping. This avoids the previous problems with multidegree-of-freedom systems and demonstrates the necessity for defining the type of energy transformation before any experimental or analytical work can be done. In the absence of a mechanical equation of state, it is still impossible to define damping for aperiodic, stochastic, or transient, motion although internally consistent definitions are practically possible for lightly damped systems. The nomenclature proposed by the USA Standards Institute Committee S2-W-33 will be discussed.
Rating of Noise Exposures for Hearing Conservation
Authors: Glorig A.
Published: September 2005

A simple noise-exposure rating scheme is proposed—the equal energy concept based on dB(A) and summated time. A suggested formula for summating time at various dB(A) levels is proposed. The formula makes it convenient to summate the levels in terms of a no-risk reference level. No specific exposure level is suggested. Rather, a series of dB(A) levels at 5-dB increment, with the associated risk of hearing impairment, are presented, together with the background material upon which this proposed rating scheme is based.
Rating of Noise with Respect to Speech Inferference
Authors: Webster J. C.
Published: September 2005

Two simple noise-rating schemes are proposed—the three-band preferred frequency speech interference level (SIL) and A weighting (LA). The proposed SIL is the simple arithmetic average of decibel sound-pressure levels in the octaves centered at 500, 1000, and 2000 Hz. These simple noise rating schemes are interpreted in a nomograph relating distance between talker and listener and voice level. An additional interpretation over the older SIL, voice-level, and distance table is the inclusion of the voice level expected to be used in specific calculated noise levels (the Lombard voice-level reflex). Relationships between A weighting and the new SIL, the old SIL (based on average levels in the octaves ranging from 600 to 4800 Hz), and other noise rating schemes will be listed. Limitations of applicability to quasisteady-state noises within spectrum slopes of −12 and +9 dB/oct, etc., will be noted. Some of the background experimental results and validation studies specifying suggested criterion levels will be discussed briefly.
Rating of Noise with Respect to Annoyance
Authors: Green D. M.
Published: September 2005

The tentative draft of a standard for the rating of annoyance of noise will be described. The primary calculation method will be perceived noise level (PNL) with a secondary, simpler method, being A level. Additive corrections to these basic noise-level calculations will involve spectrum, shape, and duration. Several unresolved issues will be discussed, such as the difference between “annoyance” and “loudness,” and the problem of multiple noise exposures, such as airplane flyovers.
Measurement and Evaluation of Stationary Noise Sources
Authors: Baade P. K.
Published: September 2005

There are significant differences in the characteristics of machines and their noise radiation as well as in the purposes for which machine noise is measured. These have to be taken into account in developing practical sound test codes. If the data are merely to indicate whether the machine noise meets a specific criterion at a specific point of evaluation, measuring sound pressure at that point will suffice (see CAGI-PNEUROP sound Test Code). For general sound-control design purposes, however, sound-power spectra are necessary. Under both reverberant and semifree field conditions, great care is required when the noise contains pure tones [see ASHRAE Transactions 70 (1964) pp. 217 and 228]. The impedance seen by ducted fans has to be controlled as it will affect the sound power generated [see ASHRAE Transactions 74, Part 2, (1967), page V.1.1]. Machinery sound control by design also requires detailed knowledge of sound transmission paths. Transmission and insertion loss ratings and standards still do not cover many important configurations.