bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamental Methodology for the Evaluation of Sound Quality and Some Results of Its Applictaion
Authors: Koshikawa T. , Nakayama T.
Published: September 2005

From the point of view of the design for the sound quality of acoustical manufacture, the following method was determined as the way to construct the scale of sound quality. Firstly, we considered the model of evaluation dividing the process of judgment into three steps: sensory, affectional, and over-all quality judgment. Secondly, Torgerson's multidimensional scaling method was taken for the scaling of sensation as the 1st step. Judgments were performed under the criterion of sensory similarity between the various sound qualities represented in the form of complete method of triad. Also, the psychological meaning of scale dimensions was determined by means of sensory adjectives that are suitable to indicate the contents of similarity, and are described by the subjects immedidately after the above-mentioned judgments. As the results of applications to the typical reproducing system that contains the two kinds of distortions, band restriction and nonlinearity, it was shown that there are at least three elemental sensations originating from the low- or high-frequency components and noisiness, respectively.
Heartprints of some Arrhythmias and Systolic Murmurs
Authors: Schwartz M. L. , Kersta L. G. , Spindel L. D.
Published: September 2005

Quantitation (as a function of frequency) of the varying intensities of the first heart sound has been accomplished in 15 cases of arrhythmia (artrial fibrillation) using contour spectrogram prints; the latter were described previously [J. Acoust. Soc. Am, 36, 1050 (A) (1964)]. A summary of these findings and prints of additional instances of ejection systolic murmurs due to aortic and pulmonic valvular stenosis and other causes is also presented. Possible future uses of the contour spectrogram in the medical field include correlation of sound amplitude with hemodynamic measurements and continued exploration for distinctive patterns among similar murmurs of different etiologies.
Use of Noise to Eliminate One Ear from Masking Experiments
Authors: Weston Peter B. , Miller James D.
Published: September 2005

To evaluate the possibility that one ear can be eliminated from a masking experiment by use of the noise, the following requisite facts were determined: (1) if a tonal signal mixed with noise is received at one ear, the addition of a noise to the other ear negligibly reduces the tone's threshold if the noises are statistically independent; (2) in contrast, the added noise distinctly reduces the tone's threshold if the noises are perfectly correlated; (3) facts (1) and (2) are ohserved whether the noise level at the ear that receives the tone is less than, equal to, or greater than the noise level at the ear that does not receive the tone; and (4) if identical tones are presented to the two ears and if the signal-to-noise ratio is about 25 dB lower in one ear than in the other, the effect of the tone at the ear with the lower signal-to-noise ratio is eliminated from the experiment. [Work supported by Public Health Service Program-Project grant No. B-3856 from the National Institute of Neurological Diseases and Blindness, National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Continuous versus Gated Masking for Noise and Sinusoidal Maskers
Authors: Green David M.
Published: September 2005

A gated sinusoid of 110 sec duration is masked either by (1) continuous noise or (2) gated noise that overlaps the signal in time. The gated condition is slightly more effective in masking the signal by about 2 dB. This result is consistent with the findings of Watson, of Pfafflin and Mathews, and with the original report of Sherrick and Mangabeira-Albernaz. A second study compared these same two conditions, using a sinusoidal masker. For the sunusoidal masker, the gated-masking condition was about 15 dB more effective in masking the signal than the continuous masker. It is argued that the size of the critical band may be different for continuous sinusoids and continuous-noise maskers, thus causing a greater difference in the change in masking effectiveness when the gated conditions are employed. [Research supported in part by the National Institutes of Health, U. S. Department of Health, Education, and Welfare, grant NB-04949-01, and by the National Science Foundation, grant GB 1462.]
Investigation of the Dynamic Properties of the Neural-Quantal Model
Authors: Markowitz Joseph
Published: September 2005

A 2-interval, 4-alternative psychophysical procedure was used in which the signal could occur in (a) the first interval only, (b) the second interval only, (c) both intervals, or (d) neither interval. The observer was forced to choose one of these 4 alternatives. Comparison of the detectability in either interval alone, with the detectability in both intervals, allows one to estimate temporal dependencies. The neural-quantal model predicts strong temporal dependencies over short periods of time. On the other hand, theories of the signal-detectability variety have generally assumed independence. Two experiments were conducted. In the first, the signal was a pulsed sinusoid in noise, in the second, a phase-locked increment in a sinusoidal background. [Research supported in part by the National Institutes of Health, U. S. Department of Health, Education, and Welfare, grant NB-04949-01, and by the National Science Foundation, grant GB 1462.]
Note on Underwater Horns
Authors: Muster D. , Christensen A.
Published: September 2005

Various types of free-flooding finite horns are used to load both faces of a piezoelectric transducer. The general axisymmetric configuration of each horn type tested is the same; it is comprised of a straight, frontloading horn and a folded, back-loading horn, such that the mouths of the two loading horns are concentric. Each horn type tested has the same throat dimension, folding geometry, theoretical cutoff frequency, and was tested with the same piezoelectric transducer. Experimental data taken over the frequency range of 1000–20 000 cps are presented and compared with those which theory would predict from the design geometry. [This work supported by the U. S. Office of Naval Research.]
Experimental and Theoretical Investigation of the Sound Field of a Corrugated Acoustic Waveguide
Authors: Jones J. D.
Published: September 2005

An investigation of the sound field of a corrugated acoustic waveguide has been conducted. The waveguide was constructed by stacking equally spaced circular disks coaxially along a solid rod to form a corrugated cylindrical surface of circular cross section. Measurements of the sound field near the surface of the waveguide show that a dominant mode that has the form of a cylindrical surface wave exists at the corrugated surface. These experimental results are used as the basis both for the development of a theoretical model for the corrugated region of the waveguide and for the theoretical analysis of the farfield radiation pattern of the waveguide. Farfield radiation patterns were measured as a function of the length of the waveguide. These measured patterns are compared to the theoretical radiation patterns. [Work done under a contract with the U. S. Office of Naval Research.]
Acoustic Reflection and Transmission Properties of Several Transducer Window Materials
Authors: Barnard G. R. , Bardin J. L. , Whiteley J. W.
Published: September 2005

Measurements were made to determine the reflection and transmission coefficients of several transducer window and dome materials. The coefficients were measured as a function of incident angle in the frequency range 100–500 kc/sec. The effects of the shear component as well as the absorption of both the longitudinal and shear waves are discussed. Refined values for the magnitude of the shear velocity and the absorption can be obtained by fitting the calculated values to the experimental curves. (Work supported by the U. S. Navy Bureau of Ships.]
Dynamic Pressure-Gauge Calibrator
Authors: Mines D. O.
Published: September 2005

No satisfactory theoretical or experimental method has appeared by which it is possible to obtain economically for a complicated pressure gauge the diaphragm deflection as a function of the frequency of an applied sinusoidal pressure, over a frequency range that includes the natural diaphragm resonance. An experimental method is described by which a piezoelectric driver is employed to generate a sinusoidal pressure of continuously variable frequency and amplitude in a confined gas, to which one side of a test diaphragm may be exposed. Equations are derived describing the gas-coupling medium and the driver, so that the characteristics of the apparatns may be predicted. The apparatus is proven experimentally, using a series of thin, circular, clamped-edged plates whose dynamic response is both calculated and determined by ringing. Finally, the apparatus is employed to successfully determine the dynamic response of a commercial 500-psi pressure transducer connected to the generator by various lengths of tubing. The mechanical resonance of the transducer diaphragm and the acoustic resonance of the path through the tubing are both displayed.
Measurement of Noise Radiated by Boundary-Layer-Excited Panels
Authors: Maestrello Lucio M.
Published: September 2005

Measurements are presented of the sound power radiated by panel excited by turbulent boundary layers with air velocities up to Mach number 0.64. The test panels were mounted in a test section of an acoustically quiet air duct that was enclosed in a concrete reverberation room. The mean-square exciting pressure fluctuation of the wall and the mean-square panel displacement in broad and narrow bands were measured. The radiated sound power and mean-square displacement was found to vary proportional to (Mach No.)A × (panel thickness)−B, depending on the predominant modes of vibration. Some of these results are compared with flight-test data.
Sound-Power Spectra from Subsonic Jets
Authors: Barnett Norman E.
Published: September 2005

Power spectra generated by small subsonic cold-air jets were investigated in a reverberation room. Near sonic velocity, the results were consistent with the accepted description of jet noise: a broadly peaked spectrum related to Strouhal number and 8th-power law. At lower flow velocities, significant deviations occurred: the broad-band power was larger than expected but proportional to less than 8th power of velocity; the spectrum flattened; and the peak, if such a term remains appropriate, shifted towards higher not lower frequencies. These results were observed both for a given nozzle operated at various flows and for geometrically related nozzles of different size. These results suggest that the usual description of jet noise be reserved for the high subsonic-velocity range and be incorporated as a special case within a broader description of jet noise. The broader description is vaguely perceived at present since this research, whose purpose lay in a different direction, has only provided strong evidence of the need for a more comprehensive description. [This paper drawn from research sponsored by the Systems Engineering Group, U. S. Air Force.]
Response of Anisotropic Cylindrical Shells due to Local Acoustic Pressure
Authors: Yao John C.
Published: September 2005

The dynamic equation of motion for anisotropic shells is first formulated with the effects of internal fluid, internal pressure, and viscous damping taken into account. For practical purposes, the system is reduced to a Donnell-type equation with the radial displacement as the single dependent variable. The response of the shell due to local acoustic pressure of discrete frequency is then analyzed by using the normal-mode solution. The calculation is facilitated by first plotting the free vibration spectra of the cylinder. Based on the spectra, the resonant modes for a given forcing frequency are isolated and the response can be accurately calculated by considering only the components of the pressure identical to those modes. Since the Fourier-series expansion for a local load usually involves thousands of modes, the process proposed here greatly simplifies the response calculation. Numerical results obtained herein are presented in charts.
Method for Analyzing Harmonic Spectra of Wide Dynamic Range
Authors: Prout James H.
Published: September 2005

A study of distortion in high-intensity underwater sound pulses required that the signals be recorded at sea on magnetic tape to be analyzed later in the laboratory. An equalized preamplifier is described that was used to adjust the dynamic range of these signals to that of the tape. A rising slope of 18 dB/oct was found suitable for most recording of this type. The design of the equalizer, considerations necessary for the use of magnetic tape for distortion studies, and method of laboratory analysis are described. Some typical spectra produced by this method are shown.
Real-Time Electronic Spectrograph for Analysis of Acoustic Transients
Authors: Germano J. F. , Halley R. , Allen W. B.
Published: September 2005

A real-time electronic spectrograph that produces a time-versus-frequency display on a cathode-ray storage tube is described. A DELTIC (DElay Line TIme Compressor) is used to obtain high-frequency multiplication ratios aad thereby essentially real-time analysis with a swept-filter heterodyne analyzer. The device examines the time-frequency structure of a stored sample. The resulting output displays the complele content of the store in one recirculation per bandwidth. The entire sample is thus analyzed in a fraction of a second. Pulses, tones, and noise transients were used to text the capabilities of the analyzer with respect to time resolution, frequency resolution, response to noise, and processing gain. Results of these tests aad other illustrative examples of the analyzer output are presented, which show that (1) frequencies separated by one bandwidth or more can be resolved, (2) pulses shorter than the filter buildup time are lengthened whereas pulses longer than the buildup time retain their original length, and (3) the device does not respond to level changes of white noise at the input.
Optimal Detection of an Unknown Discrete Waveform that is Recurring Randomly in Gaussian Noise
Authors: Hinich M. J.
Published: September 2005

Suppose that we wish to detect the times that an unknown, but fixed, SONAR signal θ(t) arrives at a hydrophone in the presence of additive Gaussian noise with known covariance. The signal consists of a known number of amplitude-modulated pulses. We do not know these amplitudes. Due to random delays in the medium, we can assume that the arrival times of the signal are purely random. We sample the output from the hydrophone by taking, nonoverlapping discrete-time records, each being of fixed, finite length. Results are obtained for the optimal likelihood-ratio detection of the signal for very low signal-to-noise ratios. If ∫θ(t)dt, the dc value of θ(t) is nonzero, then the test statistic is simply the sum of all the observations in the record. The detection problem is closely connected with the estimation of θ(t). Results are given for efficient estimation of θ(t), using the tools of large-sample theory. [Work supported by the U. S. Office of Naval Research 27T024.]
Use of Amplitude Information in Sequential Signal Detection
Authors: Roberts Richard A.
Published: September 2005

The optimum receiver design for a signal of unknown amplitude, i.e., amplitude specified by a probability distribution, for detection and classification in added white Gaussian noise is developed for sequential and nonsequential observation procedures. Assuming specific prior amplitude information, performance of the optimum device is evaluated in terms of the receiver-operating characteristic and average observation time. Computation of detection performance for a signal-known-exactly receiver in an environment where the signal amplitude is distributed indicates the degradation of performance caused by ignoring statistical amplitude information. [Work supported by the U. S. Office of Naval Research, Code 468.]
Function Filtering
Authors: Cordell E. L. , Beason R. J.
Published: September 2005

The magnetic-tape recorder has been given a new role, that of a function filter. Frequency response of the two-head tape system is shown to be a function of tape speed, gap length, gap width, and misalignment. Use of these characteristics to build special filtering properties into a tape machine is described. Use of the tape machine as a narrowband filter is described mathematically. This concept is extended to encompass its use as a filter to extract signals of a particular waveform or waveshape from among other signals. The transfer function of the filter is derived mathematically and also obtained experimentally from the response of the filter to an impulse signal. Experiments are described in which the function filter is used to detect the presence of a pulse of energy swept in frequency in a background of band-limited white noise. Signal-processing gain achieved and dynamic range of operation are discussed. Advantages of this unique filter in certain applications are described.
Necessity of Adaptive Receiver Realizations
Authors: Nolte L. W.
Published: September 2005

From classical fixed-time signal-detection theory, it is known that the basis for optimum receiver design is likelihood ratio. For composite-signal hypothesis problems, the optimum receiver forms a total likelihood ratio that is an average over all the various possible signals that could be transmitted in the observation interval. When the transmitted signal is composed of one of a finite class of waveforms that is repetitively generated by a random independent trigger process, the various possible signals that could occur grow with time so that a classic nonsequential realization requires a growing memory size that is impractical to implement. In problems of this type, the optimum reciever can be realized in an equivalent sequential fashion that is an adaptive realization. Using adaptive realizations, the receiver can be realized with a memory size that remains fixed in size. [This work supported by the U. S. Office of Naval Research, Code 468.]
Ultrasonic Image Converter of High-Conductance Scanning Type
Authors: Turner W. R.
Published: September 2005

In an electronic ultrasonic image converter, a plate of piezoelectric or polarized electrostrictive material transduces the ultrasonic image into an alternating surface potential that can be detected by a scanning electronic beam. The conversion characteristics of the plate are explored for various forms of electrical loading, including the conditions necessary for the retrieval of the energy stored mechanically in a resonant plate. The parameters for the high-conductance electron-beam scanning necessary for this energy retrieval are developed. An image tube employing these principles is described.
Principles of Ultrasonic Imaging
Authors: Moseley Donald S.
Published: September 2005

Sound energy can be focused by lenses and mirrors. These may function as concentrators or as producers of images, according to the use. Design requirements are more stringent for the latter, as consideration must be given to meeting dm Rayleigh criterion of path length and to minimizing aberrations. Experimental corroboration of optical principles carried over to acoustics is now easier with a practical image converter and accompanying electronics, which presents in visual form the sonic image. In contrast to optical imaging, diffraction can be the major source of image degradation since the sonic wavelengths are three orders of magnitude longer than the usual optical wavelengths.
Transdec is Operational
Authors: Green Charles E.
Published: September 2005

The Transducer Evaluation Center constructed on Point Loma, San Diego, is now in full operation with a capability better than that ascertained from the scale model. The anechoic capability of the pool is satisfactory without the use of an absorbent trap as originally planned, even for a spacing between transducers under test as great as 80 ft. The bridge that spans the pool is acoustically isolated from the water and forms a rigid mounting structure for transducers. The electronic equipment is capable of operating over the range from 50 cps to 1 Mc/sec in either a pulse, steady-state, or narrow-hand-tracker mode. The transmitting-current or voltage-response level, or the open-circuit voltage-sensitivity level of a transducer, is plotted directly on an analog recorder. Some transducers have already been evaluated at frequencies as low as 100 cps and other transducers as high as 1.1 Mc/sec. Accuracies better than ±0.2 dB are the rule.
Intensity Meter for Underwater Use
Authors: Schloss Fred , Sykes Alan O.
Published: September 2005

The mechanical and electronic design and the calibration of two types of intensity meters are discussed and their merits compared. Both are designed for a frequency range of 50–7000 cps. The principles of both types are not new; the paper is concerned mainly with design problems and calibration procedure.
Physical and Psychological Effects of Noise
Authors: von Gierke Henning E.
Published: September 2005

A discussion of the interference of noise with normal living and comfort, including the effects on comfort, work performance and efficiency, safety, and hearing loss.
Investigation of Wave Propagation in Hollow Tubes
Authors: Heimann J. H. , Kolsky H.
Published: September 2005

The propagation of elastic waves along cylindrical shells is one of the very few wave problems that can be solved exactly. If the wavelength is Λ, the radius (r), and the thickness (h), we might expect on physical grounds that when Λ≫r the shell behaves like a rod and when r≫Λ≫h it behaves like a plate. For solid cylinders, the highest group velocity is C0=[E/ρ]12, whereas for plates it is about 1.05 C0. Physical arguments indicate that for r≫Λ≫h the higher group velocity also applies to cylindrical shells. This prediction has been tested theoretically and experimentally. First: the exact frequency equation was shown to reduce to Lamb's symmetrical and asymmetrical plate waves. Second: a computation for r/h=32 established the region of wavelengths where such plate waves are propagated. Third: experiments on pulse propagation in thin steel cylindrical shells showed a precursor wave traveling faster than C0. This did not produce circumferential strains and would appear to be the predicted plate wave.
Sound Transmission through a Finite, Closed, Cylindrical Shell
Authors: White Pritchard H.
Published: September 2005

The transmission of an acoustic wave through an infinite, homogeneous, isotropic cylinder has been derived to be a strong function of frequency and the angle of incidence between the axis of the cylinder and the incoming wave. From this analysis, two important characteristics are found: the ring frequency, where the wavelength of a longitudinal wave in the material is equal to the circumference, and the coincidence frequency, where the trace wavelength of the incident wave is equal to the bending wavelength in the shell wall. The transmission loss will take on minimum values at these two points. Measurements with 13-oct-band noise excitation of a closed cylindrical shell with l/d=1.5 show the same gross features to be present and with additional effects of low-frequency resonances, but with very little angular dependence. The presence of stiffening corrugations and irregularities in the shell leads to a random vibration field and allows methods developed for the transmission of random sound through flat panels to be successfully used for noise-reduction estimates.
Scattering Theory, with Applications to One-Dimensional Problems
Authors: Plutchok Robert , Harrison Mark
Published: September 2005

The reflection coefficients of an acoustic wave encountering a one-dimensional scattering layer, in which the velocity of propagation differs from that of the surrounding medium, can be computed by employing a recently developed analytical method. This method, which employs an integral equation technique, makes no specific reference to boundary conditions and is used to calculate the reflection coefficients, as a function of frequency, for various even-functioned scattering layers. Solution to the integral equations is obtained through an iterative procedure. It is found that in most cases because of the rapid convergence only a few iterations are needed to calculate the reflection coefficient with reasonable accuracy. Results are displayed in graphical form and compared with those obtained by other methods for similar scattering layers. [Sponsored by the U. S. Office of Naval Research.]
Analysis of Electroacoustical Transducers by Differential Immittance Techniques
Authors: Dranetz Abraham I. , Rathbun Harvey
Published: September 2005

Techniques are in use for the measurement and recording of the impedance and admittance locii of electroacoustical transducers at various levels of input power. Such data are used for determining properties such as piezoelectric coefficients, mechanical Q, resonant frequency, potential efficiency, etc. An extension of these techniques has now been developed to provide direct measurements and graphic recordings of the difference between two admittances or impedances. This approach may be used to separate the motional impedance or admittance circle from the complete locus without the need for lengthy arithmetical manipulations, and can also be used to read the minor component of impedance or admittance with greater accuracy than heretofore possible in direct-reading systems. This approach has also been applied to the measurement of the dielectric loss and capacitance of piezoelectrics under high voltage and to the separation of time variant components of impedance from time-invariant components.
Underwater-Sound Transducer with a Conical-Shell Radiation Pattern
Authors: Sanders D. R.
Published: September 2005

This paper describes the design and construction of a line transducer that has a conical-shell directivity pattern. The desired beam orientation is obtained through a combination of physical spacing of the elements of the line, connection of elements, and phasing of the driving current. Minor-lobe reduction is achieved through the use of elements cut to size to provide a shaded distribution. Measurements show the minor lobe to be about 20 dB below the main-lobe level. This particular transducer was designed to obtain bottom- and surface-backscattering data at 40 kc/sec for a grazing angle of 30° through all azimuthal angles. [Work was sponsored by U. S. Naval Ordnance Laboratory.]
Broad-Band Thermally Generated Noise Voltage of a Resonant Electroacoustic Transducer
Authors: Kendig Paul M.
Published: September 2005

Utilizing a simplified equivalent circuit for an electroacoustic transducer with a single resonance, it is shown that the mean-square thermally generated noise voltage for the entire frequency range is just kTkc2/C0, where k is the Boltzman constant, T is the Kelvin temperature, kc, is the effective electromechanical coupling coefficient, and C0 is the clamped capacitance. This voltage is generated by the mean total thermal energy in the circuit kT, which results from the circuit's two degrees of freedom. From impedance measurements on a transducer with two pronounced resonances, it has been shown that this relationship, with some modifications, approximates the conditions existing in a transducer with multiple resonances. [Research sponsored by the U. S. Navy Bureau of Naval Weapons.]
Hearing-Conservation Programs
Authors: Glorig Aram
Published: September 2005

A brief review of noise-exposure criteria is presented, including the relations of level, spectrum, and time. Criteria are recommended. Suggestions for initiating hearing-conservation programs are made. Educational materials are presented and methods for their use are given. Noise control at the source is discussed and comparisons of personal protective devices are made.
Effects of Intensity Level on Threshold Shifts Produced by Pulsed and Continuous Maskers
Authors: Dirks Donald D. , Chandler Jane
Published: September 2005

The effect of pulsed versus continuous maskers as a function of intensity level was investigated. The test signals were pulsed or continuous pure tones at the frequencies of 250, 1000, and 4000 cps. A wide-band random noise was presented either to the test ear (monotic) or the contralateral ear (dichotic) of four trained observers at intensity levels of 15, 30, 45, 60, and 75 dB SPL. Three methods of presentation included: (1) pulsed tone and pulsed masker (simultaneous); (2) pulsed tone and continuous masker; and (3) continuous tone and continuous masker. The results from the monotic and dichotic conditions showed that (a) for a pulsed tone signal the pulsed masker was more effective even at the low intensity levels, and (b) a continuous masker produced greater masking in the high frequencies if the tone signal was also continuous. During the dichotic condition, increased threshold shifts were observed as the intensity level of the noise increased. This result was most evident for the pulsed-pulsed and continuous-continuous presentations. The differential effects of frequency were considered in the interpretation of the results. [This work was supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Change in Simultaneous Masking of Short Tones by Narrow- and Wide-Band Noise Bursts
Authors: Elliott Lois L.
Published: September 2005

The onset of a 10-msec tone relative to the onset of a 500-msec noise (70 dB SPL) was delayed by 5, 20, 50, and 300 msec. Narrow masking bands were 100 cps wide at 250 cps, 200 cps wide at 1270 cps, and 400 cps wide at 2550 cps. Three highly trained subjects adjusted an attenuator to determine tone threshold. Zwicker's “overshoot,” defined as the pure-tone-masked threshold at 5-msec time delay minus the threshold at 300-msec delay, is greater at high frequencies than at low for wide-band masking. With narrow-band masking at 2550 cps, very little overshoot occurred for frequencies within the band, while 14-dB overshoot occurred for frequencies above (e.g., 4 kcps) and 12-dB overshoot for frequencies below (e.g., 1.9 kcps) the masking band. Overshoot occurred for pure-tone frequencies above the narrow band at 1270 cps but not below. No clear effects occurred with the narrow band at 250 cps. A method of constant stimuli produced comparable results. Findings are related to Scholl's hypothesized temporal development of the critical band. [Work supported by National Institute of Nervous Diseases and Blindness Program-Project, U. S. Department of Health, Education, and Welfare.]
Plane Piston at Finite Amplitude: Second Harmonics
Authors: Williams A. O. , Ingenito F. , Westervelt P. J.
Published: September 2005

Three years ago, we presented a perturbation analysis of this problem, but later showed that it partly disagreed with experiment [J. Acoust. Soc. Am. 34, 723(A), 1985(A) (1962)]. The difficulty now seems to be removed. Again, a perturbation equation for the second harmonic generated in the beam from a circular plane piston, radiating finite-amplitude sound into a fluid, is solved by using a Green's function, expanded—as is the “driving term”—in plane waves. The resulting 9-fold integral, oversimplified previously, is tedius to work out even approximately. Results now agree well with measured axial values of acoustic pressure, which show a pronounced dip and recovery just before the far field begins. This and other details somewhat obscure the expected initial linear rise of second-harmonic pressure with axial distance from the source. The method also treats off-axis points, but evaluation and computation are still more formidable. Nevertheless, the behavior of this practical acoustic source is clarified. [Work supported in part by the U. S. Air Force Systems Command.]
Analysis-Synthesis of Glottal Excitation
Authors: Michaels Sheldon B. , Soron Henry I. , Strong William J. , Lieberman Philip
Published: September 2005

A high-speed motion picture was used to obtain the time-dependent glottal opening for a speaker phonating /a/. The pressure waveform measured by a microphone at the speaker's lips was also recorded on film simultaneously with the glottal opening. A digital computer with a scope and light-pen facility was used to extract the glottal area and pressure waveform on a frame by frame basis. Van den Berg's relation for the resistance of the glottis to steady air flow was then used to calculate the time-dependent glottal volume velocity. The volume velocity was then used to excite a POVO. The output from the POVO was compared with the pressure waveform recorded during phonation. Volume velocities calculated for different subglottal pressures and a “standard” triangular waveform were also used to excite the POVO. Psychoacoustic evaluations were made of the natural quality of the various synthesized outputs.
Synthesis of Components of Voice Quality
Authors: Laver J. D. M. , Lawrence Walter
Published: September 2005

An attempt has been made, using the Edinburgh resonance analog speech synthesizer (PAT) to simulate various voice qualities in a long stretch of connected synthetic speech. The components of voice quality include supralaryngeal modifications such as nazalization, pharyngalization, etc., and laryngeal modifications (varieties of phonation type) such as whisper, falsetto, breathy voice, harsh voice, and creaky voice. The acoustic variables used for constructing the voice qualities were fundamental-frequency range, formant-frequency ranges, formant bandwidths, addition of varying amounts of hiss to voicing in the formant excitation, and variation of the spectral weighting of the hiss and the voice components of the source. Some of the more successful simulations are demonstrated and a tape recording of all results is available for those wishing to study them in greater detail.
Lossfree Twin-Tube Resonator and the Vowel Triangle of Hellwag
Authors: Mol Hendrik
Published: September 2005

It is not necessary to regard the performance of the lossfree twin-tube resonator merely as an oversimplification of the physical processes taking place in the real vocal tract. Instead, the twin-tube resonator can be regarded as a formant generator capable of producing the same formants as the real vocal tract, using a minimum number of parameters only. By changing the variables in the well-known tangent formula for the formants of the twin-tube resonator, a new simple nomogram can be derived that directly leads to the classic vowel triangle of Hellwag as published in his thesis [Tübingen (1781)]. The parameters of the twin-tube resonator can be traced in most x-ray photographs of the vocal tract. For [u]-like sounds, the back resonator of the twin-tube seems to be a poor substitute for the in reality wasp-waisted back cavity, but it is doubtful whether this is a serious drawback.
New Spectrum Analyzer for Speech Analysis
Authors: Rengman Ulf , Liljencrants Johan
Published: September 2005

A new spectrum analyzer, mainly for speech sounds, is described, featuring high accuracy and a high degree of flexibility. The signal to be analyzed is applied to a filter bank, comprising up to 51 bandpass filters. The filters are switchable into 11 different preset combinations of center frequency and bandwidth to provide either wide-range coverage for formant analysis or narrow-range coverage for harmonic analysis. For complete coverage in the latter case, a stepwise variable heterodyne system is used to transpose the input signal sequentially. The bandpass filters are followed by individual rectifiers, smoothing filters, and analog-to-digital converters. Multiplexing is consequently performed on digitized signals without loss of accuracy and dynamic range. The output is presently displayed on an XY recorder, giving spectrum sections, but it is proposed to record the output digitally on computer tape in IBM compatible format. It is also proposed to record visible speech on 35-mm film. The selected sampling points are identified by means of a time code, recorded on the second track of the double-track input tape.
A New Standard for the Field Measurement of Airborne Transmission Loss
Authors: Schultz Theodore J.
Published: September 2005

The American Society for Testing Materials is currently preparing a new tentative recommended practice for the measurement of airborne-sound insulation in buildings. In several respects, this proposed standard departs radically from the recommended laboratory measurement procedures (E90-61T), in order to cope with problems commonly met in the field: (1) it is assumed that there is a “field transmission loss” for a partition, differing from the value that would be obtained for a similar partition in a laboratory, measurement because of the various interactions of the test sample with its environment in the field; the recommended procedures attempt to measure this field transmission loss with no effort to “correct” the data to laboratory values; (2) to deal adequately with the many situations that may be encountered in the field, measurement procedures are recommended in terms of “types” or models of those situations for which we have at present suitable measurement techniques; if a field-measurement situation can be shown (by the suggested tests) to correspond (within certain limits) to one of these types, then the measurement procedure for that type is to be used; this entails five different test procedures at present; (3) a test is required to demonstrate the absence of flanking transmission in all field measurements; (4) in cases where transmission loss is not an appropriate measure of sound isolation, alternate procedures are recommended for determining noise reduction or insertion loss.
New Method of Measuring Reverberation Time
Authors: Schroeder M. R.
Published: September 2005

A new method of measuring reverberation time is described. The method uses short pulses of acoustic energy, such as pistol shots or tone bursts, to excite the enclosure. An integral over the response of the enclosure yields, in a single measurement, the average of infinitely many decay curves that would be obtained with random noise as the excitation signal. The smooth decay curves resulting from the new method improve the accuracy of reverberation-time measurements and facilitate the detection of nonexponential decays. In a recent publication [J. Acoust. Soc. Am. 37, 409–412 (1965)], the fundamental relationship between decay curves obtained from impulse and noise excitations, on which the new method is based, was proved. In this talk, progress with instrumenting the new method is described. Results obtained in a large concert hall are described subsequently (B. S. Atal, M. R. Schroeder, G. M. Sessler, and J. E. West. Paper J5, this meeting).
Reverberation Times and Early Energies in Philharmonic Hall (New York)
Authors: Atal B. S. , Schroeder M. R. , Sessler G. M. , West J. E.
Published: September 2005

The data collected in Philharmonic Hall between May 1963 and October 1964 (before, during, and after alterations) were evaluated according to the method for measuring reverberation times described earlier [M. R. Schroeder, Paper J4, this meeting]. The results reveal nonexponential decays for many parts of the Hall. The initial reverberation time (based on the first 10 dB of the decay) at midfrequencies (500–1000 cps), averaged over 12 positions in the empty Hall, dropped from a value of 1.7 sec before alterations to 1.4 sec after absorptive treatment of the rear walls to reduce echoes. The recent installation of a solid stage enclosure raised the initial reverberation time to 1.6 sec. The final reverberation time, based on later portions of the decay (for example, 5–35 dB) was found to be about 2.0 sec before alterations and 1.85 sec after absorptive treatment of the rear walls. It is noteworthy that even the final reverberation times are lower than those previously attributed to the Hall. Evaluations were also made of the early energy (the energy of the direct sound and that arriving within the following 50 msec). On the main floor of the Hall, the early energy between 100 and 250 cps increased by 8 dB relative to midfrequencies, resulting in a better spectral balance. This improvement can be attributed to the new stage enclosure and to the elimination of the gaps between the ceiling panels.
Re-Vision of the Speech-Privacy Calculation
Authors: Young Robert W.
Published: September 2005

The articulation index used in telephone communication, the listening equation for SONAR, and the acoustical privacy calculation of architectural acoustics are all founded on a computation of an excess of signal level over noise level just sufficient to permit some stated detectability. From this viewpoint, data compiled for “Speech Privacy in Buildings” [Cavenaugh, Farrell, Hirtle, and Watters, J. Acoust. Soc. Am. 34, 475–492 (1962)] have been reviewed for possible simplications in their procedure for estimating acoustical privacy. In lieu of the “dot counting” method, ratings of sound isolation here investigated include the sound transmission class (STC), a similar index being discussed for international standardization (IISO), and a frequency-weighted sound isolation; as measures of ambient noise, in lieu of curves to be fitted for different spectrum shapes, sound level (A) and frequency-weighted octave-band sound-pressure levels have been tested. The reported judgments of be correlated at least as well with ratings based on these presently considered measures of sound isolation and noise as with those originally employed. Accordingly, ways of substituting one kind of rating for another have been derived.
Power-Level Criteria for Noise Control
Authors: Ashley Carlyle M.
Published: September 2005

Speech intelligibility in rooms such as classrooms, conference rooms, theaters, and auditoria, where a speaker must be heard by a “marginal” listener at the far end of the room, depends on the ratio of noise power to speech power regardless of room size and absorption. Thus the expression of noise criteria in terms of power is both simpler and more accurate in assuring speech intelligibility than the present practice of specifying sound-pressure levels. In a paper, “Simplifying Room Sound Power Calculations” [ASHRAE J. (July 1963); ASHRAE Trans. (1963)], the author found that the mean octave-band sound-power level in the speech frequency range should not exceed 44 dB re 10−12 W for 0.8 articulation index with normal voice power. A total range of 12 dB covers variations of speech intelligibility and speech power. For other types of rooms, the acceptable noise power is proportional to room-surface area. A simplified chart is also presented for estimating “room effect” from room size and type. The advantages of the direct use of sound-power level as a criterion are shown by further experience.
Estimating the Acoustic Loading on Building Structures near Launch Sites
Authors: Eldred Kenneth McK. , Sutherland Louis C.
Published: September 2005

The growth in acoustic power of space-vehicle boosters has been accompanied by an even greater increase in low-frequency noise—a significant source of damaging, or annoying, building vibration. To evaluate this significance, the forces developed by acoustic loading are considered and criteria for building vibration damage reviewed in terms of existing criteria for static and dynamic building loads. Upon first examination, a comparison of the approximate equivalent static forces for acoustic loads with conventional building design loads from wind, blast, and earthquake will show that the latter are usually predominant. However, a more detailed analysis shows that, under certain circumstances, the acoustic load may be expected to be a significant factor in basic building design or in design of structural sections. This situation is illustrated by an example that includes the effects of diffraction, joint acceptance for an unbaffled obstacle, and possible coupled ground vibration. In addition, the relative significance of internal vibration from structural transmission or by internal acoustic excitation is compared and criteria for damage or annoyance are reviewed.
Measuring and Monitoring Low-Frequency Space-Vehicle Noise
Authors: Dyer Ira
Published: September 2005

Recent years have seen substantial advances in the techniques and equipment for measuring and monitoring low-frequency noise. Systems for measuring and monitoring noise in the vicinity of airports have been developed, followed closely by systems for space-vehicle static-test and launch sites. The latter differ principally from the former in that lower frequencies and greater distances are of interest. Also some static-test measuring systems are organized to evaluate the sound-propagation path by using a known signal prior to the inception of the static test, as a means for deciding on possible damaging effects of the noise. Advances have also been made in the calibration of transducers at low frequencies. Several measuring and monitoring systems now in operation are described, and their physical bases and design principles are discussed.
Some Research Features and Capabilities of the Langley Low-Frequency Noise Facility
Authors: Edge Philip M. , Mayes William H.
Published: September 2005

In response to a need for research to determine possible effects of low-frequency noise associated with the launching of large spacecraft, the Langley Research Center has constructed an acoustic facility to operate in the frequency range from 1 to 50 cps. This facility makes use of a large, hydraulically driven speaker to generate sound-pressure levels of the order of 160 dB in a chamber of sufficient size to environmentally test full-scale manned spacecraft. This paper contains brief discussions of some research problems relating to low-frequency noise, the general design features of the facility, and some of the research capability available. The discussion of research capability includes brief descriptions of research under way. This research includes environmental tests of man and response and transmission tests both of flight-vehicle structures and of building structures. In addition to the capability for discrete frequency and random-noise testing, capability for testing with acoustic pressures of the impulse type having application to research relating to sonic boom is indicated.
Some Biological Effects of Ultrasound
Authors: Hughes David E.
Published: September 2005

Effects of ultrasound are discussed on “elementary” biological systems. These include components (such as mitochondria and DNA) isolated from cells, intact cells of various types, and viruses.
Ultrasonic Absorption by Protein Solutions
Authors: Edmonds Peter D.
Published: September 2005

Detailed molecular mechanisms for explaining the measured absorption by aqueous solutions of proteins are not known. Only hemoglobin at 20°–25°C has been studied over as much as four decades of frequency [Carstensen and Schwan, J. Acoust. Soc. Am. 31, 305–311 (1959); Edmonds, Biochim. Biophys. Acta 63, 216 (1962)]. Absorption in excess of that due to viscosity is observed over the whole frequency range and a broad maximum occurs between 10 and 100 Mc/sec. A distribution of relaxation times extending from about 8 μsec to about 0.5 mμsec is required to fit the experimental data. Mechanisms responding with the shorter relaxation times are believed to include structural reorganization of the hydrogen-bonded complex (hemoglobin-water) and of the protein side chains that associate by hydrophobic bonding. The former mechanism is invoked by analogy with aqueous solutions of amines [Andreae, McKellar, and Edmonds, J. Acoust. Soc. Am. 34, 1984(A) (1962); Acustica 15, 74–88 (1965)] and the latter by comparison with the calculations of Némethy, Steinberg, and Scheraga [Biopolymers 1, 43 (1963)]. Current measurements on aqueous solutions of amino acids are mentioned. [This work supported by the Public Health Service, U. S. Department of Health, Education, and Welfare.]