bluuebunny/crossref_metadata_2025 huggingface dataset:
Transfer Function of the Middle Ear
Authors: Møller Aage R.
Published: September 2005

The transfer function of the middle ear was investigated in anesthetized cats. The amplitude and phase angle of vibration of the malleus, incus, and round window for constant sound-pressure level at the eardrum was measured by a capacitive probe. The acoustic impedance at the eardrum in the frequency range from 200 to 8000 cps was also measured. The acoustic impedance at the eardrum was found to be proportional to the ratio of sound pressure at the eardrum and velocity of the malleus from about 200 cps to 4 kc/sec, showing that the eardrum acts as a rigid piston in this frequency region. By comparing the amplitude of the malleus and that of the round window, it was found that the coupling between the malleus and the cochlear fluid is very rigid. A second-order low-pass function described by its Laplace transform was found to be a good approximation to the experimental data, up to a frequency of about 4 kc/sec, or approximately 4 times the cutoff frequency. In the frequency range where the eardrum acts as a rigid piston, it is thus possible to estimate the transfer function of the middle ear entirely from the acoustic impedance data in the plane of the eardrum.
Large Signal Methods for the Study of Psychoacoustics
Authors: Tanner Wilson P.
Published: September 2005

Certain difficulties occur in weak signal studies which can be avoided if large signal studies can be utilized to study the same phenomena. Weak signals are those which are employed in detection experiments. They are those which are commonly considered to be in the “threshold” range for the noise level employed in the experiment. Large signals are those well above the noise level, so large that a detection experiment would be impractical. The problems encountered in weak signal experiments involve the observer's ability to remember parameters of the signal such as frequency and amplitude. Uncertain memory has effects on detection rates which are functions of the signal level. These effects are difficult to isolate from those arising from the properties of the auditory mechanism, and these appear to be inseparable if weak signal studies alone are employed. One would expect some of these memory effects to disappear in large signal recognition experiments. With large signals, frequency memory has relatively small effect on the observation, signal itself carrying the necessary information. Amplitude memory can be eliminated by presenting two signals, the observer being asked to state which is the louder. (This experiment in its operation is identical with one employing a comparison tone and a standard.) Performance in experiments of these types theoretically depends on the energy of the difference signal, and optimum performance is indicated by the ratio 2E/N0, where E is this energy. Using the variable d′, an observer efficiency can be determined, thus permitting an estimate of the memory effects. Data are presented for weak and large signal experiments first estimating the effect of frequency memory and then estimating the effect of amplitude memory. The method of using large signal studies as a substitute for weak signal studies in investigating the hearing mechanism is described. (20 min.)
Some Effects of Experience on the Threshold of Audibility
Authors: Zwislocki J. , Maire F. , Feldman A. , Rubin H.
Published: September 2005

The question whether the measured threshold of audibility improves with experience has widespread implications. It refers to the nature of the threshold itself, but it also affects the psychophysical experiments involving comparisons of thresholds of audibility. If practice has no effect, then the amount of experience of the listeners can be disregarded and results obtained on groups of listeners with unequal sophistication may be compared with each other. If the opposite is true, experiments using threshold comparisons would require either pretaining of the listeners or careful counterbalancing. In several experiments, inexperienced listeners showed statistically significant improvement in their threshold of audibility with practice. Depending on the experimental conditions, the average improvement amounted to from 4 to 10 db. Experiments performed on several groups of listeners under similar conditions, yielded practically identical results.
Auditory Fatigue Produced by Continuous and Interrupted White Noise
Authors: Spieth Walter , Trittipoe William J.
Published: September 2005

Is the temporary hearing loss following exposure to repeated bursts of white noise determined by the long-time average level or the burst level of the noise? Thresholds of a 4-kc interrupted tone were obtained for eight subjects before and after two minutes of exposure to the following noise conditions: a noninterrupted noise at 120 db SPL and also at 110 db SPL, and interrupted noises with a burst level of 120 db SPL and with “on” and “off” durations of 1 and 9, 10 and 90, 100 and 900, and 1000 and 9000 milliseconds, respectively. The long-time average level of the interrupted noises thus was 110 db. Results indicate that the shifts in threshold did not differ greatly among the various interrupted noises. The average amount of fatigue produced by the interrupted noise was closer to that produced by the noninterrupted noise at 110 db than that produced by the noninterrupted noise at 120 db. Therefore, within the conditions examined, the fatigue produced by an interrupted noise is more nearly determined by the long-time average level than by the burst level.
Hearing of Naval Aircraft Maintenance Personnel
Authors: Dixon Ward W.
Published: September 2005

Audiograms were obtained on 1200 naval enlisted men at NAS Cecil Field, Florida. Although hearing losses were slightly greater among men exposed to noise from reciprocating engines and nonafterburner jets than among those not exposed, one cannot confidently ascribe the difference to noise, since the noise-exposed group had also been exposed to more gunfire. Follow-up audiograms taken on a representative sample of the men working with jets possessing afterburner showed no additional hearing loss after six months of moderate exposure. A similar negative result was found in a study of flight-deck personnel during a three-month cruise aboard an aircraft carrier.
Excess Absorption in Mercury
Authors: Hunter J. L. , Welch T. J. , Montrose C. J.
Published: September 2005

The ultrasonic absorption and velocity in liquid mercury have been measured at 90, 150, and 270 Mc/sec over a temperature range from 25° to 130°C. No variation of absorption with frequency was found within experimental accuracy. The classical value has also been computed over this range of temperatures. It has been found that the measured value exceeds the classical value, and the difference is ascribed to volume viscosity. The most probable value of ηv/ηs over this range was found to be approximately 0.45.
Noise Shield for Microphones Used in Noisy Locations
Authors: Hawley Moses E.
Published: September 2005

A rubber noise shield was developed which significantly improves the speech-to-noise ratio at a military microphone. The construction and evaluation techniques are described, and the advantage of introducing acoustic damping material is shown. (This paper reports a portion of the work performed under contract W-33-038-ac-18181.)
Sound-Pressure Measurement without Energy Absorption
Authors: Koidan Walter
Published: September 2005

With a condenser microphone diaphragm exposed to a sound field, an electrical potential of the same frequency is simultaneously applied to the microphone terminals at such a magnitude and phase as to prevent motion of the diaphragm. This null technique is performed by operating the microphone in a carrier-frequency detection system. A direct measurement of the pressure can be made from the electromechanical coupling constant, φ = (p/e)u−0, where e is the voltage applied to the microphone terminals, p is the sound pressure at the diaphragm, and u is the volume velocity of the diaphragm. Some applications are as follows: (a) Sound pressure can be measured at a point of infinite acoustical impedance, such as at the end of an impedance tube, without extracting energy from the system. (b) Microphone parameters, including φ, can be obtained by a reciprocity method with a reduction in the number of assumptions. (c) The calionbrati of microphones at high sound intensities in a resonant tube is simplified, since it is possible to substitute microphones having different mechanical impedances without affecting the sound pressure.
Sound Materials in the Experimental Media of Musique Concrete, Tape Music, and Electronic Music
Authors: Ussachevsky Vladimir A.
Published: September 2005

An entirely new means of muscial expression, the use of recorded material on tape for the purpose of muscial composition, is now being systematically explored in several studio laboratories abroad and in the United States. For the past ten years muscial experimentation has relied more and more upon electroacoustical apparatus as the principal means for enlarging a sound vocabulary. Recorded sounds from multiple sources are being subjected to extensive mutation through the application of filters, ring modulators, tape-speed variation, intricate tape splicing, electronic reverberation, etc. The tape recorder's function as a recording and playback mechanism has been extended to that of a performing solo instrument in a symphony orchestra. This paper gives a résuḿ of sound sources explored and of the new apparatus developed to manipulate sound; it describes some of the techniques used, and it illustrates with recorded excerpts certain typical results obtained through controlled evolution of electronic and nonelectronic sounds as they are shaped to become components of complex sound textures in this new experimental medium.
Underwater Sound Reverberation in the Arctic Ocean
Authors: Mellen R. H. , Marsh H. W.
Published: September 2005

Results of experimental studies of sound reverberation from the ice in the Arctic are presented and interpreted. The ice causes reverberation levels as much as 40 dB greater than those encountered from the icefree sea surface. An rms roughness of 3 m is indicated.
Reply to S. S. Stevens
Authors: Warren Richard M.
Published: September 2005

Stevens believes that judgments of sensation intensity reflect the operating characteristics of the sense organs. In a recent note, he criticized the physical correlate theory as ignoring sensory physiology. This charge is refuted. Peripheral neural processes are a complex function of stimulus intensity, while psychophysical judgments follow the simple rule: equal stimulus ratios produce equal subjective ratios. It is concluded that central nervous-system processes are responsible for the direct relation between subjective intensity and the physical correlate of sensation.
Acoustic Hydrodynamic Interaction Hypothesized
Authors: Momsen Charles B.
Published: September 2005

An experiment has been conducted to show that the presence of a sound field in water accelerates the sinking of a glass sphere through the water.
Effect of Pressure on Ultrasonic Relaxation in Electrolytes
Authors: Carnevale E. H. , Litovitz T. A.
Published: September 2005

Measurements of the pressure dependence of the ultrasonic absorption were made on aqueous solutions of manganous sulfate and ammonium hydroxide. Absorption data were obtained for manganous sulfate at frequencies from 9 to 75 mc/sec, up to pressures of 3930 kg/cm2 and at a temperature of 60°C. The relaxation frequency increased from 19.1 mc/sec at atmospheric pressure to 30.7 mc/sec at 3930 kg/cm2. Absorption measurements in ammonium hydroxide were obtained at frequencies from 15 to 75 mc/sec, up to pressures of 2030 kg/cm2 and at a temperature of 45°C. The relaxation frequency increased from 21.2 mc/sec at atmospheric pressure to 52.0 mc/sec at 2030 kg/cm2. The results in both electrolytes can be explained on the basis of a chemical dissociation. In both electrolytes a decrease in the volume difference between the products and reactants with pressure is necessary in order to account for the pressure dependence of the sound absorption.
Ultrasonic Pulse Technique for Measuring Acoustic Losses and Velocities of Propagation in Liquids as a Function of Temperature and Hydrostatic Pressure
Authors: McSkimin H. J.
Published: September 2005

A fixed path ultrasonic unit based on the method of Schulz [Z. angew. Phys. 7, 144 (1955)] is described which can be used for measuring acoustic wave velocities and losses in liquids as a function of temperature and hydrostatic pressure. Careful transducer design makes possible measurements at frequencies as high as 200 mc/sec for low loss liquids. A simple phase balance technique insures a high order of accuracy for velocity determinations. Illustrative data for carbon tetrachloride, Dow Corning DC-703 and DC-200 silicone fluids, and for water are shown. Determination of freezing points of liquids using ultrasonic waves for indication is also discussed briefly.
Derivation and Application of the Fokker-Planck Equation to Discrete Nonlinear Dynamic Systems Subjected to White Random Excitation
Authors: Caughey Thomas K.
Published: September 2005

The Fokker-Planck equation is derived and applied to discrete nonlinear dynamic systems subjected to white random excitation. For the class of problems in which the nonlinearities involve only the displacements of the system, it is shown that exact solutions can be constructed for the stationary Fokker-Planck equation. It is further shown that if stationary solutions exist they are unique.
Interferometric Determination of Ultrasonic Absorption in Liquids
Authors: Gutowski F. A. , Schuele D. E. , Carome E. F.
Published: September 2005

A modified interferometer system has been developed to determine the absorption of ultrasound in liquids. The operation of this system, which ultilizes a liquid-air interface as the reflecting surface and a simplified electrical detection circuit, is based on the measurement of the acoustic resistance of the liquid column as a function of column length. Measurements have been made of the absorption coefficient of castor oil at 3 Mc over the temperature range from 10 to 45°C. Though they differ in some details, in general the results compare well with those obtained by various investigators using other measurement techniques.
Zero Crossings, Peaks, and Other Statistical Measures of Random Responses
Authors: Crandall Stephen H.
Published: September 2005

Several statistical properties of a stationary random process that are of interest in random vibration applications are reviewed. In the first three sections, the zero crossings, threshold crossings, distribution of peaks, and a simple model of fatigue damage are obtained directly from calculations based on the joint probability density p(x,ẋ). It is assumed that p(x,ẋ) is available, e.g., from the Fokker-Planck equation. In the fourth and fifth sections, it is alternatively assumed that x(t) is the response of a particular nonlinear oscillator to random excitation. It is shown that certain statistical results can be obtained by utilizing the oscillator properties. Two illustrative examples are described in the sixth section. Finally, in the seventh section, the directions for future research on higher-order statistics are sketched.
Measurement of Ultrasonic Absorption in Liquids by Streaming Methods
Authors: Piercy J. E.
Published: September 2005

A promising method of investigating molecular problems in liquids is through the study of acoustic relaxations. This investigation is severely hampered by the limited range of frequencies over which the sound absorption may be measured with suitable conventional techniques (about 5 to 200 Mc for a typical liquid). The lower frequency limit in these techniques is determined primarily by the measurement error due to diffraction, and the smallness of the absorption coefficient which multiplies all the measurement errors. It is shown that both difficulties can be avoided by methods based on the measurement of acoustic streaming. An apparatus for the study of acoustic relaxations in liquids by this method is described. With this apparatus, absorption coefficients from 0.0001 to 0.1 cm−1 may be measured over the frequency range 0.6 to 10 Mc, representing for a typical liquid an extension of the available frequency band from 5 to 8 octaves. Experimental problems which are encountered in the measurement of acoustic streaming are discussed, with particular emphasis on the thermal convection caused by the absorption of acoustic energy—a major effect which has not previously been resolved.
Compositional Techniques and Electronic Media
Authors: Babbitt Milton
Published: September 2005

The current intensive development of, and musical interest in, electonic media have been motivated by the evolution of nonelectronic compositional techniques which demand such media for their realization. The source of much of this development is “serial composition,” of which the most highly developed and influential self-contained instance is the twelve-tone system. The elements of a serial system are pitch classes (congruence classes), the relations among them are defined—for a specific composition—by a linear ordering, and the operations upon them can be defined by the permutations resulting from complementation and translation with regard to pitch number and order number. These operations are applicable also to duration classes, elements of the same pitch class, dynamics, timbre, and complexes of these elements. The structuring demanded by such systems requires control of temporal length, intensity, ensemble rhythm, and flexibility of succession unattainable with nonelectronic media. The known correlations between the acoustic and auditory domains must be employed to secure the required muscial precision. Nonempirical timbral identification, timbral hierarchization, rhythmic quantization, and fusion are among the immediate problems requiring solution for the purposes of autonomous electronic composition.
Empirical Evidence for Nonlinearity and Directions for Future Work
Authors: Lyon Richard H.
Published: September 2005

The effects of nonlinearity in several clamped clamped beam vibration problems are reviewed. Possible effects are: jump or instability phenomena, amplitude-limiting effects, and distortion of probability densities. Studies of prototype panel frame structures show similar behavior. The necessity for extending these efforts to built-up structures is emphasized. Also, estimates for the onset of nonlinearity based on two simple models are made to show how one can be guided in experimental design by quantitative-empirical considerations.

Some theoretical techniques are appraised for their applicability to the structures problem. In particular, two approximation methods are singled out for detailed comment. Finally, the possibilities of a more creative use of experimental analysis and a closer tie between theoretical and experimental effort in structures research are explored.
Single Estimates of Pitch Magnitude
Authors: Beck Jacob , Shaw William A.
Published: September 2005

Six hundred three Os each made a single numerical estimate of pitch magnitude with respect to a standard of either 523 or 131 cps. The standards were assigned a value of 100. Six comparison frequencies were presented: 131, 262, 523, 1047, 2093, and 4186 cps. The questions posed are: Will the frequency of the standard affect magnitude estimations of pitch when each O makes a single magnitude estimation? What are the effects of the context provided by multiple judgments on the Os' magnitude estimations of pitch? The results show that the choice of the standard may affect magnitude estimations of pitch when biases due to multiple judgments are eliminated. The medians obtained with a standard of 523 cps fall close to the revised mel scale [S. S. Stevens and J. Volkman, Am. J. Psychol. 53, 329–353 (1940)], while the medians obtained with a standard of 131 cps fall below it. In answer to the second question, a comparison of the pitch functions obtained using single estimates with the pitch functions obtained using multiple judgments reveals that the context provided by multiple judgments has two main effects. Multiple judgments act to increase the overall steepness of the pitch functions obtained, and effects associated with the frequency of the standard may be made more marked when multiple judgments are used. The results suggests that it is probably risky to decide on the form of the pitch function on the basis of the data obtained with either multiple judgments or with single judgments, using only one standard.
Effect of Circumaural Earphones and Earphone Cushions on Auditory Threshold
Authors: Stein Laszlo , Zerlin Stanley
Published: September 2005

Threshold-sensitivity curves for the Sharpe HA-10-C circumaural earphone and the CZW-6 circumaural earphone cushion mounted on the TDH-39 earphone were derived relative to the MX41/AR cushion-TDH-39 earphone combination. Median-threshold pressures for the Sharpe earphone, using a flat-plate coupler, were also determined.
Diplacusis and Auditory Theory
Authors: Ward W. Dixon
Published: September 2005

Following exposure to a series of high-intensity pulses that produced a marked auditory fatigue at 1000 cps and above, significant tonal binaural diplacusis was found to exist at even lower frequencies. The mean shift, for 6 listeners, in the frequency of a tone in the fatigued ear required to match the pitch of a fixed tone in the unexposed ear, was 6.5% at 500 cps, 4.5% at 200 cps, 2.5% at 150 cps, and zero at 100 cps. It is concluded that the perception of the pitch of pure tones can be mediated by the frequency of neural discharge only when the tonal frequency is 100 cps or lower.
Effects of Filtering and Vocal Duration upon the Identification of Speakers, Aurally
Authors: Compton Arthur J.
Published: September 2005

The purposes of this study were to investigate (1) the effect of various conditions of high-pass and low-pass filtering of the voice upon the identification of speakers; (2) the effect of various durations of recorded segments of the voice upon the identification of speakers; and (3) the relationship of fundamental frequency to misidentification of speakers. Fifteen recorded segments of the vowel [i] for each of 9 speakers were presented to listeners. All listeners were familiar with the speakers' voices through daily contact. The 15 segments of the vowel differed only in duration. The samples of the speakers' voices were heard under 7 conditions of high-pass and low-pass filtering. The task of the listeners was to identify the speakers by writing the name of one of 9 speakers after the presentation of each vowel stimulus. The results of the investigation indicate that (1) durations of 1/40 of a second are sufficient for identifying speakers; (2) the greater the severity of filtering, the greater the duration of the sample of voice required for identification of speakers; (3) attenuation of frequencies of the voice below 1020 cps does not affect the ability of listeners to identify speakers; (4) attenuation of frequencies of the voice above 1020 cps substantially reduces the ability of listeners to identify speakers; and (5) there is an inverse relationship between the relative degree to which speakers' voices are confused and the range, in cps, between the fundamental frequencies of the speakers' voices.
Oppositely Directed Finite Waves
Authors: Fat R. D.
Published: September 2005

The general method of attack that was found to be successful in the analysis of plane progressive finite waves has been adapted to the analysis of a sound field that comprises two such waves progressing in opposite directions. The interference phenomena associated with the meeting of two isolated pulses are first investigated. Neglecting viscous losses, it is found that the pulses are transmitted through each other unchanged except that the speed of transmission of each pulse is modified by the other in the region of interference. It is further found that, to the zero and first orders of approximation, the particle velocity in the region of interference is the vector sum of the particle velocities in the isolated component pulses. With these relationships established, the nature of the phenomena in a sound field of the indicated type in a steady state can be predicted to the indicated order of approximation. (This investigation is supported by the Office of Naval Research, contract N5 ori-07861.)
Combating Echo in Speech Circuits with Long Delay
Authors: Gardner Mark B. , Nelson John R.
Published: September 2005

In speech-communication systems, echo is universally present to a greater or lesser extent. It goes unnoticed, however, on short connections where the round-trip transit time is too small to give an audible separation of direct and reflected components. For circuits of moderate delay, echo suppressors have long served to alleviate the problem of echo return. Present equipment, however, does not provide satisfactory performance when the delay becomes relatively large. In view of the current interest in satellite communication, a number of studies of echo-suppressor performance for longer delays have been undertaken. The present paper is a report of one such study in which an AB-type screening test was used to evaluate the circuit innovations employed. These include diode-type variolossers for introducing and removing echo attenuation on a “soft-switch” basis and “time-logic” circuitry for reducing such attenuation during periods of double talking. Results indicate that, while the circuit innovations employed add perceptibly to suppressor performance, only a partial solution of the problems involved has been achieved. This is particularly true for circuits having line-loss and talking-level asymmetries.
Spectrographic Study of Vowel Reduction
Authors: Lindblom B.
Published: September 2005

Measurements of formant frequencies and duration are reported for 8 Swedish vowels uttered by a male talker in three consonantal environments under varying timing conditions. An exponential function is used to describe the extent to which formant frequencies in the vowels reach their target values as a function of vowel-segment duration. A target is specified by the asymptotic values of the first two formant frequencies of the vowel and is independent of consonantal context and duration. It is thus an invariant attribute of the vowel. The results suggest an interpretation in terms of a simple dynamic model of vowel articulation.
Investigation of the Precision of an Articulation-Testing Program
Authors: Stuckey Charles W.
Published: September 2005

A mathematical model of the individual articulation scores of a team of listeners during their training period was contrasted to a similar model for a fully trained articulation team. Statistical hypotheses of whether or not a particular team had received sufficient training were tested by evaluating the learning process of a team being trained. It was concluded that this procedure of training evaluation is valid and that after 20 hours the team was fully trained in terms of the criterion adopted. The effect of memorization on the articulation scores was evaluated and found to be negligible. The maximum variance of a trained team was found and the precision of the results was computed as a function of the number of repetitions averaged. By averaging the scores from a sufficient number of repetitions, any desired degree of precision could be obtained. The articulation team was found to be a very precise and reliable measuring instrument for ranking voice-communications equipment in terms of intelligibility.
Noise Reduction of Rectangular Enclosures with One Flexible Wall
Authors: Lyon Richard H.
Published: September 2005

The noise reduction produced by a small rigid enclosure with one flexible wall is computed. It is assumed that the critical frequency of the wall lies above the first acoustic resonance of the enclosure. The noise reduction is computed for very low frequencies where both wall and enclosed volume are stiffness-controlled, for frequencies where the wall is resonant and the volume is stiff, and for frequencies where both the wall and the acoustic space have resonant behavior. In the last case, a comparison made with the usual noise-reduction calculations based on forced wave-transmission loss. The noise reduction computed in this paper turns out to be less than the value computed by that more “classical” approach.
Cortical Responses to Repeated Clicks and Bursts of Noise
Authors: Goldstein Moise H. , Kiang Nelson Yuan-Sheng
Published: September 2005

Synchronous neural activity has been recorded by gross electrodes from the auditory nerve in response to repeated impulsive stimuli at rates up to 2000/sec. However, cortical activity, recorded by gross electrodes exhibits no directly identifiable stimulus-locked responses at rates as low as 100/sec. For rates higher than 5/sec the amplitude of cortical responses to repeated stimuli decreases. Overlapping of and interference between successive responses as well as a lack of synchrony contribute to the reduction in size of the cortical responses. Gross electrodes were placed on and in the auditory cortex of cats and steady-state responses recorded to repeated clicks, bursts of noise, and bursts of tone. Stimuli were delivered at intensity levels at which the auditory system is clearly mechanically linear. Responses from both anesthetized and unanesthetized preparations were recorded on magnetic tape and processed by a special analog computer in order to obtain the characteristics of the average response. This method permits the detection of small responses in the presence of large ongoing activity. In unanesthetized preparations synchronous cortical responses were found at rates up to 200/sec. [This work was supported in part by the U. S. Army (Signal Corps), U. S. Air Force (Office of Scientific Research, Air Research, and Development Command), and the U. S. Navy (Office of Naval Research).]
Functional Recovery and Structural Repair Following Acoustic Overstimulation of the Guinea Pig Ear
Authors: Lawrence Merle
Published: September 2005

Two series of guinea pigs were used in this study in order to investigate the nature of repair or further deterioration of the structures of the Scala Media following acoustic overstimulation. Each animal was first tested for sensitivity by determining the pressure level of sound necessary at each of 12 frequencies to produce 1 micro-volt of electrical response as recorded by a platinum foil electrode at the round window, and for linear range of the ear's response by recording the level at which the recorded potentials began to become nonlinear. Following this the ear of the animal was stimulated with a uniform spectrum of noise: the first series at 150 db above 0.0002 dyne/cm2 and the second at 138 db, measured at the drum membrane by a probe-microphone calibration system. Sensitivity and linear range were again measured, the operative wound closed, and the animal allowed to recover for 56 days, at which time it was reoperated and the above measures made again. The animal was then sacrificed by intra-vital perfusion of Maximow's fixative and the temporal bones removed for histologic processing. All specimens were eventually cut and mounted serially so that graphic reconstructions could be made for comparison of the anatomical condition of the structures of the Scala Media with the functional changes as measured electrically. It appears that individual susceptibility to damage is more a function of the ear's ability to recover than it is of structural weakness. One cannot predict on the basis of initial loss alone, regardless of level of stimulation, whether the ear will, with time, recover some sensitivity or lose it. The determining factors do not show up histologically in a normal ear because they are probably related to the nutrition of the sensory cell. These conclusions and others will be discussed in the light of the experimental evidence.
Identification of Elementary Auditory Displays: Effect of Unbalanced Probabilities of Occurrence
Authors: Pollack Irwin , Boynton James
Published: September 2005

Listeners identified sound levels from a series in which one sound level occurred twice as often as each of six other sound levels. Unbiased measures of identification performance indicated that highest identification performance is achieved for the most frequently presented category and, that lowest identification performance is achieved for categories adjacent to the most frequent category.
Sonoluminescence and the Chemical Effects of Cavitation
Authors: Hickling Robert
Published: September 2005

It has been suspected for some time that sonoluminescence and the chemical effects of cavitation are caused by the same thermal mechanism. It would seem, however, that the connection is even more intimate, since the existence of certain radicals appears to be essential for both phenomena. This is discussed briefly in the following review.
Ultrasonic Measurements in Liquid Sulphur
Authors: Hunter J. L. , Francavilla T. L.
Published: September 2005

Measurements in liquid sulphur at 130°C show the absorption to be proportional to the frequency squared from 45 to 145 Mc/sec, with the experimental absorption about twice the Stokes value.
Recent Developments and Future Trends in Vibration Isolation
Authors: Lowe Russell T. , Crede Charles E.
Published: September 2005

The paper is in the nature of a progress report in the field of vibration isolation. It discusses the influence of newly specified environmental conditions upon the theory and practice of vibration isolation and describes several special application problems arising from current requirements. The new environmental conditions include both random vibration and steady-state vibration at frequencies beyond the range commonly considered in vibration isolation theory. Application problems of current importance involve the maneuvering conditions and operating loads encountered in modern military aircraft and guided missiles. The particular roles of isolators in increasing the reliability of electronic equipment, in lending validity to laboratory tests, and in adding versatility to industrial plant layout are discussed. The paper concludes with a discussion of unsolved current problems and comments on possible future trends in isolator design. (25 min.)
Calibration of Shock and Vibration Pickups
Authors: Ramberg Walter
Published: September 2005

Several methods are available for the precise calibration of shock and vibration pickups. These will be reviewed critically. The methods are described in an ASA Standard which is being prepared on “Methods for the Calibration of Shock and Vibration Pickups.” They may be regarded as members of a “hierarchy” starting with standards calibrated by absolute methods or by the reciprocity method and going from there by several steps to working standards suitable for calibration in the field. The paper will include a discussion of calibration methods which are now under development and which promise to extend the range of frequencies and amplitudes covered by this hierarchy of calibration methods.
Response Spectra by Means of Oscillograph Galvanometers
Authors: Conrad R. W. , Vigness Irwin
Published: September 2005

A response spectra (shock spectra) is the response of a series of single-degree-of-freedom systems of given damping to a shock or vibratory motion as a function of the frequencies of the systems. An oscillographic galvanometer can be considered a single-degree-of-freedom system having a rotational response to an exciting current. If the exciting current is made proportional to the amplitude of a motion, the response of the galvanometer to the current will be proportional to the response of a single-degree-of-freedom system to the motion, provided their natural frequencies and damping properties are the same. A commercial galvanometer-type oscillograph has been obtained having twelve undamped galvanometer elements with natural frequencies in the range between 10 and 2500 cps. Damping by electrical means has been made adjustable between 2% and 50% of critical. Associated circuitry has been constructed so that electrical playback of recordings of shock and vibratory motions can be conveniently analyzed. Calibration techniques are described and examples are given for analysis of simple and complex shock motions, and for nonperiodic vibrational motions.
Attenuation of Explosive Sounds in Sea Water
Authors: Marsh H. W.
Published: September 2005

It is shown that the measurements of Arons may be used to predict an apparent attenuation similar to that observed by Sheehy, Ewing, Thorpe, and Urick. It is conjectured that this attenuation is characteristics of the propagation of an impulse and not of oscillatory waves.
Sonic Vibration as Exemplified by the RB-66
Authors: Kennard Dwight C.
Published: September 2005

The results of an intensive experimental study of the RB-66 flight vibration characteristics are presented. This study produced data on variations of vibration with air speed at constant engine power and data on the statistical distribution of vibration amplitudes in selected fixed frequency bands. The vibration characteristics under ground runup conditions are correlated with measured external sound levels. Other significant trends and relationships of pertinent parameters are pointed out. It is concluded that the sound and vibration conditions determined for the RB-66 may be useful in clarifying concepts of sonic vibration applying to other types of aircraft subjected to intense jet noise.
On the Power Gained by Clipping Audio and Single Side-Band Speech Signals
Authors: Wathen-Dunn Weiant , Lipke David W.
Published: September 2005

Available statistical distributions of instantaneous speech amplitudes have been examined, and an arbitrary but reasonable peak factor has been chosen for a clipping reference level. The power increase in the audio wave (and hence the AM or DSB side bands) due to peak clipping in the audio band has been calculated by using the standard deviation of the clipped and unclipped distributions as a measure of the root-mean-square voltage. A curve will be presented showing the power gain as a function of clipping, and the relation of this to the intelligibility will be pointed out. Statistical distributions of the envelope of a single side-band speech signal have been run and compared with those taken by others, and these have been treated in a manner similar to the audio case to determine the power gained by clipping the single sideband signal. A curve of the power increase under these conditions will also be presented. Unfortunately, there are no data on the intelligibility of clipped single side-band speech to which the computed curve may be related.
Peakpicker: A Band-Width Compression Device
Authors: Peterson Eugene , Cooper Franklin S.
Published: September 2005

A vocoder of the usual channel type has been used as the basis for a comparatively crude form of resonance vocoder. Supplementary equipment—the Peakpicker—is located between analyzer and synthesizer of the vocoder to carry out two functions, namely, to select spectrum channels containing voltage maxima and to establish connection from analyzer to synthesizer for the selected channels. All circuits of the vocoder proper are retained and used without change. The spectrum information to be transmitted can now be reduced, since at any moment only those channels are utilized in which voltage maxima are detected. The Peakpicker and an 18-channel vocoder have been tested for selection of three, four, or five spectral maxima at sampling rates of 30 or 60 per sec. Under the best conditions thus far, nonsense syllable articulation scores in the 60% to 70% range have been realized, corresponding to high sentence intelligibility scores. It is estimated that this level of performance can be had with an over-all information rate well below 1000 bits per second. Illustrative recordings will be presented. (This work was supported by the Department of Defense in connection with Contract DA49-170-se-1642.)
Effect of Varying the Interaural Noise Correlation on the Detectability of Tonal Signals
Authors: Robinson Donald E. , Jeffress Lloyd A.
Published: September 2005

Data are presented on the effects of varying the interaural correlation for noise on the detectability of a 500-cps tonal signal. The noise correlation was reduced by adding uncorrelated noise in the noise channels to the ears. Comparisons are made between data obtained with this method of reducing the noise correlation and with previous data obtained by introducing a displacement in time in the noise to one ear. Masking-level differences are presented, based on fifty-percent thresholds, obtained with the constant method and on the detectability index d′ obtained in a two-interval, forced-choice situation.
Speech Research Devices Based on a Channel Vocoder
Authors: Borst John M. , Cooper Franklin S.
Published: September 2005

Three tools for analysis-synthesis research on speech have been developed, employing an 18-channel vocoder as the basic speech processing device. One is a vocoder-playback (Voback) which produces speech sounds from hand-painted spectrograms. Frequency zones of the spectrogram corresponding to the pass bands of the channel filters are scanned by 18 multiplier phototubes to provide control voltages for the vocoder synthesizer. Two additional phototubes provide control of pitch and buzz/hiss switching. A second device (Intonator) permits arbitrary manipulation of the pitch of real speech as it passes through the vocoder. The speech is supplied to the vocoder from a loop of magnetic tape which runs in step with a variable-area pitch-control tape and a reference spectrogram. Phototubes supply pitch and buzz/hiss voltages to the vocoder synthesizer. A closely related device (Amplituder) permits instant-by-instant control of output level. A control voltage obtained from a phototube and variable-area tape is used to regulate a variable-gain output stage. Recordings from the three devices will be presented. (This work was supported in part by the Carnegie Corporation of New York, and in part by the Department of Defense in connection with Contract DA49-170-sc-1642.)
Ratio Scales, Category Scales, and Variability in the Production of Loudness and Softness
Authors: Schneider Bruce , Lane Harlan
Published: September 2005

Several studies have shown that category scales are nonlinearly related to ratio scales of subjective magnitude. A variability model has been proposed previously to account for this departure from linearity. This article examines the model in the light of the empirical relations that enter into it: the ratio scale of subjective magnitude, the corresponding category scale, and the variability of judgments in both physical and psychological units. These relations are determined, through repeated measurement with a single observer, for the psychological continuum, loudness, and its inverse, softness. The ratio scales are shown to be reciprocals, and the category scales complements. The category scale of softness is more concave downward, relative to its magnitude scale, than is the category scale of loudness. This outcome is also derived mathematically from the empirical equations relating the four scales to physical magnitude. Variability is found to increase with increasing stimulus magnitude at the same rate for both loudness and softness productions, expressed either in physical units or in psychological units. Hence, the variability model is found not to accord with the observed difference in concavity between softness and loudness category scales relative to their respective psychological magnitude scales.
Disjuncture as a Cue to Constructs
Authors: Bolinger Dwight L. , Gerstman Louis J.
Published: September 2005

It is commonly thought that constructs such as light housekeeper and lighthouse-keeper are distinguished by means of stress differences alone. The significant factor in “stress” is presumed to be intensity, pitch changes (if any) being incidental. Spectrograms reveal another factor: “disjunctures,” or gaps between the syllables, which seem to correspond in width to the closeness of the semantic bond. Tests were therefore devised to oppose stress and disjuncture in order to determine whether either cue was paramount in making the distinction. The words light, house, and keeper were recorded with wide pauses between them as well as in the contexts (He's a) lighthouse-keeper and (She's a) light housekeeper (with contrastive stress on light). By shortening and lengthening the disjunctures of the three versions, each was made to resemble each other version, while leaving the stresses and pitches unaltered. Listeners judged each utterance, regardless of its original source, to mean what the disjunctures conveyed: the narrower the disjuncture between light and house and the wider the disjuncture between house and keeper, the more the listeners tended to hear lighthouse-keeper, and contrariwise for light housekeeper. The original differences in stress had no influence on the judgments. (This work was supported by the Carnegie Corporation of New York.)
Diffraction of Plane Waves by an Elliptic Cylinder
Authors: Barakat Richard
Published: September 2005

The diffraction of plane waves by an elliptic cylinder is studied by employing expansions in Mathieu functions. Both Dirichlet and Neumann boundary conditions are investigated. The scattered intensity in the far field and total scattered power are derived and their long-wave (Rayleigh) scattering approximations studied. Numerical results are presented for both the long-wave and medium-wave regions.
Transverse Vibration of Beams with Internal Damping, Rotary Inertia, and Shear
Authors: Snowdon J. C.
Published: September 2005

The manner in which the Timoshenko equation may be extended to predict the response to vibration of beams with internal damping has been discussed in detail. The conventional form of the Timoshenko equation describes how the presence of rotary inertia and shear displacement influences the vibrational response of beams when the bending wavelength is not large as compared with the beam thickness. Analysis has been developed in general terms, although, when considering the specific examples of center-driven “free-free” and simply clamped beams, it has sometimes been assumed that equal damping factors are associated with the complex shear and Young' moduli. This is normally realistic assumption for plastic and rubberlike materials, which possess relatively high internal damping. Representative computations of beam response have been performed and contrasted with results obtained from the simpler Bernoulli Euler theory, which assumes that the influence of rotary inertia and shear displacement may be disregarded.
Noise Measurement of Subsonic Concentric Jets
Authors: Lee R. , Smith E. B.
Published: September 2005

Noise measurement in terms of total acoustics power and spectrum analysis was made for small concentric jets of various diameter and velocity ratios within a reverberant box. Total acoustic power radiated by concentric jets may be expressed by the following equation: Pac = Kρ0c0−5ApUp8[1 + ArUr8], where ρ0 and c0 are the density and velocity of sound at ambient condition, Ap and Up are the area and mean exit velocity of the primary jet, and Ar and Ur are the area and velocity ratios between secondary and primary jets, respectively. Coefficients K were experimentally determined for various combinations of velocity and jet diameter, and then compared with K for zero secondary velocity. Results indicate that the order of magnitude of K does not change within the experimental range. This means that secondary flow has little effect in bringing about a “favorable” turbulence structure necessary to achieve noise reduction. The effect of varying the distance between primary and secondary exit planes is also shown.