bluuebunny/crossref_metadata_2025 huggingface dataset:
Distributions of Transportation and Community Noise
Authors: Buchta Edmund
Published: October 2005

For traffic, aircraft, and community noise control, we try to specify the changing noise with the A-weighted sound level. For the transportation and community noise with a smooth and continuous time character, we get the A-weighted sound levels in the form of single numerical values. With respect to annoyance, these values agree with the community reaction to noise. If the noise levels have a wide statistical variability in a wide dynamic range with different time patterns, it is difficult to find a single number or an equivalent level that could characterize the whole complexibility of the changing noise, even if we use a statistical analyzer. The cumulative sound-level distribution describes the time structure of the noise in analogy to the spectrum for the frequency structure. In recent years, extensive survey data were obtained in many cities (i.e., Düsseldorf, Tokyo, Budapest, Prague, etc.) and converted in cumulative distributions. Data were obtained also in residential areas close to a major airport. The effect of the aircraft noise in addition to traffic and community noises is discussed in detail in this paper. Cumulative distributions of the A-weighted sound levels were developed for establishing noise control regulation for traffic and aircraft noise.
Education and Enforcement—Noise Control Provisions of the New York City Building Code
Authors: Kodaras M. J.
Published: October 2005

A paper entitled “Noise Control and the New York City Code Project” was read at the 67th Meeting of the Acoustical Society in the Spring of 1964. Since then, the Code has become a law for optional application after 1 January 1969 and mandatory use after 1 January 1970. This paper provides a review of the noise-control provisions of the Code and gives information regarding the initial acceptance of the Noise-Control Provisions as well as steps taken and planned to aid architects, engineers, building inspectors, and others in the understanding and enforcement of these provisions.
Field-Performance Acoustical Measurements—Dependable and Economic Means to Code Enforcement
Authors: Oliphant Kenward S.
Published: October 2005

This paper provides a review of the practical applications for field testing in buildings of the following: ASTM E336-67T, “Measurement of Airborne Sound Insulation in Buildings”; ASTM (Rm 14-2) proposed classification for determination of sound-transmission class; ASTMC 423-66 standard method of test for “Sound Absorption of Acoustical Materials in Reverberation Rooms”; and impact (structureborne) testing techniques utilized by National Bureau of Standards as published in “FT/TS—24 January 1968.” A discussion follows outlining the codification required to implement nondestructive field testing as the quality assurance for enforcement of building noise-control codes, including experience with such code work in various levels of government in the State of California.
Testing of Noise Emission by Plumbing Appliances
Authors: Strumpf F. Michael
Published: October 2005

A standardized method of testing noise emission by plumbing appliances is very important for industry as well as for testing laboratories. So far, most laboratories still have their own arrangements, and data can only be compared, therefore, on a relative basis. Draft German Standard DIN 52218 for the measurement of plumbing noise in laboratory and field conditions is discussed. In addition, an evaluation is given of experience obtained with this standard and, in particular, with the Standard Noise Source (part of this setup) as tested under different laboratory conditions.
Multiple Scattering of a Pulse from a Random Collection of Volume Scatterers
Authors: Boyles C. Allan
Published: October 2005

The first systematic treatment of multiple scattering based on the wave equation was made by L. L. Foldy [“The Multiple Scattering of Waves,” Phys. Rev. 67, 107–119 (1945)]. Foldy's unique contribution was the introduction of the concept of “configurational” averaging of relevant physical quantities by defining a joint probability distribution for the occurrence of a particular scatterer configuration. Although there has been a considerable amount of work done since Foldy's paper, it seems to have been done only for the scattering of monochromatic radiation. In this paper, Foldy's work is extended to include the scattering of pulses (time-limited signals). The theory is applied to the case where the random collection of volume scatterers represents a dense school of fish (or equivalently, a collection of air bubbles). The scattering properties used for a single fish are those reported by D. E. Weston [“Sound Propagation in the Presence of Bladder Fish,” AD No. 806078 (Sept. 1966)]. Consequently, the theory takes into account dispersion and absorption in the scattering volume. The ensemble average of the scattered pulse is determined as a function of time.
Statistical Analysis of Random Components of Speed of Sound
Authors: Hayre H. S.
Published: October 2005

Experimental data on the speed of sound variation with depth off the Florida Coast was statistically analyzed in order to obtain its characteristics and then to calculate their effect on ray tracing in ocean. The typical exponential depth decay of the speed of sound was removed by curve fitting in order to separate its randomly varying components. The experimental data were taken for depths up to 550 ft with an accuracy of 0.5 m/sec. The results of this work show that the probability distribution of the random component of the speed of sound is multimodal rather than of the usually expected normal form. Furthermore, the variance of the random component varies from a few tenths to up to 4 m/sec. The decorrelation distance of this random variation varies from 25 to 70 m, indicating a gross size of volume where temperature changes are correlated. This may be due to a transient temperature front or due to a volume perturbation in a stationary temperature distribution. Thus the importance of the random variations in the measurement of the speed of sound must be taken into account.
Measurement of Acoustic Backscatter in Air from Rough Surfaces using Frequency-Modulated Pulses
Authors: Markson J. L. , Stern R.
Published: October 2005

Experiments were carried out in order to measure the backscatter in air from a random distribution of rocks and gravel. Linear FM pulses were used and data were taken in the frequency range of 40–200 kHz with various modulation factors. The results obtained for the expected value of the mean-square backscatter seem to be in disagreement with many of the previously published theoretical results. An attempt is made to explain the discrepancy.
Effects of Atmospheric Variations on Sound Propagation
Authors: Burrin R. H.
Published: October 2005

In this paper, the theoretical investigation of the effects of reflections and refractions on the sound-pressure level (SPL) of a plane acoustic wave progressing through a layered atmosphere in which variations in local temperature and wind velocity exist, is discussed. The results of the investigation are presented in terms of the variation of SPL with angle of incidence of the wave on the boundary between two consecutive layers, and the importance of this angle of incidence is demonstrated. A discussion of these results is presented, and their possible bearing on the prediction and measurement of aircraft noise is considered in connection with the Federal Aviation Administration Notice of Proposed Rule Making regarding noise standards for aircraft-type certification.
Effects of Shear-Wave Propagation in a Spherical Underwater Acoustic Lens
Authors: Feldman Henry R.
Published: October 2005

The solution of the wave equation for a homogeneous solid sphere in a liquid medium subject to an incident plane acoustic wave has been computed for diameter-to-wavelength ratios up to about 100. The radial stress in the solid is calculated and compared to the pressure in the equivalent liquid sphere, i.e., one in which the dilational wave velocity and the density are the same as those of the solid. The results show that the shear wave can, under the proper conditions, interact with the dilational wave in such a manner as to improve the focusing properties of a focusing sphere. The problem of determining these “proper conditions” is discussed.
Low-Temperature Applications of the Stimulated Brillouin Scattering
Authors: Heinicke W. , Winterling G. , Dransfeld K.
Published: October 2005

The stimulated Brillouin scattering (SBS) of light is an interesting new tool in low temperature physics as will be explained by a few examples: In liquid helium, the threshold for SBS has recently been found to rapidly rise below 1.2°K. New experiments about this unexpected increase are reported. The two-pulse-method previously used for liquid helium [Phys. Rev. Lett. 22, 170 (1969)] and presently applied to solid helium has been adopted also to a measurement of the hypersonic absorption in fused quartz at 30 GHz and below 20°K. Data are presented. A new method for the possible excitation of Rayleigh waves at 10 GHz by coherent scattering of intense laser light is also discussed.
Light Scattered from Thermal Fluctuations in Gases
Authors: Broz A. , Harrigan M. , Kasten R. , Monkewicz A.
Published: October 2005

A high-sensitivity, high-resolution system for the study of light scattered from thermal fluctuations in gases has been constructed. A Bendix Channeltron photomultiplier tube with a dark noise of one-tenth of a photoelectron per second is the basis of an experimental setup, which includes a Fabry-Perot interferometer having a bandwidth of 10 MHz, with a piezoelectric scan and single mode He Ne laser. Resolution of 10 MHz is, therefore, attainable and signal levels as low as four-tenths of a photoelectron per second yield reliable data. With this apparatus, the density-density correlation function, G(r̄,t), of several gases has been investigated for a range of pressures. Whether the form of G(r̄,t) is derived from a kinetic or hydrodynamic view depends on the value of the Knudsen number—i.e., the ratio of the acoustic wavelength to the mean free path. Previous studies have concentrated on varying the angle of scattering (changing the acoustic wavelength), while this study varies the gas pressure itself (changing the mean free path), allowing a more detailed investigation of the transition from the kinetic to the hydrodynamic view. Results have been obtained from both mono- and polyatomic gases at pressures from 1 to 10 atm.
Brillouin Scattering in Liquids of High Viscosity
Authors: Bhatia A. B. , Tong E.
Published: October 2005

The spectral distribution of scattered light is calculated for the model of a liquid in which the shear and bulk relaxation processes are each characterized by a continuous set of relaxation times. The treatment is a generalization of that given by the authors previously [Phys. Rev. 173, 231 (1968)] in which bulk relaxation was ascribed to the relaxation of a thermodynamic order parameter relaxing with a single relaxation time. It is found that, in general, one has to introduce two independent distribution functions associated with the bulk relaxation times. Only when all the bulk relaxation processes are of the same types (pressure induced or temperature induced, etc.) does the expression for the spectral function contain just one distribution function, say gd(τ), for bulk relaxations. In contrast, the bulk relaxation in ultrasonic work can always be characterized by just gd(τ). The significance of these reuslts in relation to experimental data on Brillouin scattering and ultrasonic absorption in glycerine are discussed.
Speech Segmentation
Authors: Newcomb W. B. , Larkin W. D. , Houde R. A.
Published: October 2005

This paper reports a study of speech segmentation for bandwidth compression by segment coding. A segmentation procedure was desired that would segment continuous speech into units that were suitable for both classification and subsequent synthesis. Several measures obtainable for short-time spectrum information were considered: over-all amplitude, the difference in over-all amplitude between successive short-time spectra (normalized and nonnormalized) and the spectrum change between successive short-time spectra (normalized and nonnormalized). Representative speech samples were selected to include stop, fricative, nasal, and semivowel boundaries and digitized to 12 bits for computer entry. The short-time spectral data were obtained every 10 msec using a 40-msec Hanning weighting function and an FFT algorithm on the computer. The components obtained were summed to effect the desired spectrum resolution, and the desired time averaging was accomplished by summing successive short-time spectra. The above-listed measures were studied as the parameters of spectrum weighting, frequency resolution, and time averaging were varied. The analysis of the resulting data is presented.
Pauses and Circadian Rhythm
Authors: Tosi Oscar , Lashbrook Brad
Published: October 2005

Duration and statistical distribution of low levels of acoustical energy from on-going speech—perceptible and nonperceptible pauses—had been correlated with distinctive characteristics of the speakers, with temporary effects of drugs or with the speech situation. Two questions may arise to the experimenters in this field: (1) Could the circadian rhythm of the speakers interact with the distribution and duration of their pauses? (2) What is the proper relative voltage at which an electronic detector should be set to detect the moments of relatively low acoustical energy of the on-going speech, correlated with pauses? The present study attemps to answer these questions. Twelve male speakers recorded 2-min readings and 2-min spontaneous speeches early in the morning and late in the afternoon. The pauses from these recordings were detected by using the method and electronic detector named “pausimeter” and described by Tois (1966). The results of this study suggest that (1) there is not interaction of circadian rhythm with the subjects' pause durations; (2) 15% of the peak voltages of the speech waves are indicated to detect all type of pauses, 5% to detect only syntactic and nonfilled hesitation pauses.
Pure-Tone Behavioral Thresholds of the Lemur
Authors: Mitchell Curtin , Vernon Jack , Herman Paul
Published: October 2005

Thresholds were determined for pure tones of frequencies 100 Hz–40 kHz by the method of constant stimuli using a two-bar operant technique. Lemurs of two subspecies were trained to press a white bar to turn on a tone lasting 5 sec. During the tone, a single press on a second (black) bar resulted in food reward. Failure to respond simply terminated the trial. Response in the absence of tone was scored as a false positive reponse and resulted in a 12-sec shock of from 0.6 to 1.3 mA. In threshold determinations, false positive responding did not exceed 10% of total tones presented. Thresholds were obtained at 0.1, 0.2, 0.5, 1, 2, 4, 8, 15, 25, and 40 kHz using a 0.5 response probability as the definition of threshold. Preliminary results indicate sensitivity that is reasonably close to that reported for other prosimian forms, except for an apparent reduction in sensitivity at approximately 8 kHz.
Intracellular Recording from Neurons in Primary Auditory Cortex of Unanesthetized Cats
Authors: de Ribaupierre F. , Goldstein M. H.
Published: October 2005

Intracellular recordings from neutrons in the primary auditory cortex of cats were obtained using high-impedance glass pipette microelectrodes. The experimental approach and acoustic stimuli were similar to those reported previously [Goldstein et el., J. Acoust. Sec. Amer. 43, 444–455 (1968)]. Resting potentials of more than 60 mV and spike overshoot were seldom encountered. Many cells could be studied extracellularly before penetration. In these cases, spike activity before and after penetration was similar for a given acoustic stimulus. Post-synaptic potentials (PSPs) were clear in all intracellular recordings from neurons. A good correlation of PSPs and spike activity was usually obtained. Stimulation by clicks, noise bursts, or tone bursts could evoke various patterns of PSPs. Short latency EPSPs followed by IPSPs were more frequent, but IPSPs or EPSPs alone were also observed. The stimuli that evoked spikes were a subset of the stimuli that evoked PSPs [Research supported in part by the National Institute of Neurological Diseases and Stroke and the U. S. Air Force Office of Scientific Research.]
Interaction between Efferent Bundle Electrical Stimulation and Sound in Guinea Pig
Authors: Nieder P. , Nieder I.
Published: October 2005

A strong interaction effect has been found to take place between acoustic stimuli and efferent bundle activity evoked by electrical stimulation. Pentobarbital-anesthetized animals with middle-ear muscles cut and with differential electrodes in the basal cochlear turn were presented with bitonal stimuli of 20 and 400 Hz. The crossed component of the efferent cochlear bundle was stimulated using a bipolar electrode in the midline. With the 20-Hz tone absent or at low-level, efferent bundle stimulation (EBS) at 20/sec has no noticeable effect on the microphonic response to the moderate intensity 400-Hz component. With a moderate-to-intense 20-Hz component, the 20/sec EBS is effective in increasing the 400-Hz microphonic response provided the electrical pulses are delivered during the scala media positive half-cycle of the 20-Hz microphonic response. With 20 Hz at 110 dB—giving double modulation—the smaller modulation peak has been increased by more than 4% by EBS pulses delivered during the larger peak. [Research supported in part by NIH grant.]
Real-Time Analysis
Authors: Frederiksen Bent , Soeberg Jan
Published: October 2005

Brüel & Kjær type 3347 real-time 13-oct analyzer is made especially for the acoustical and vibrational field of measurements, for quasistationary periodic and random signals. A bank of 13-oct band analog filters, true rms detectors, and storage circuits make up the analyzing package. This is followed by a digital multiplexer and a logarithmic analog-digital converter featuring both analog and digital outputs. Special emphasis is laid upon the inclusion of a precision and impulse sound-level meter (per IEC 179), as well as perfect syncronism between parallax-free display scope and digital information. The total accuracy of filters and detectors is 0.5 dB. Instrument dynamic range is 150 dB, display range 50 dB. The frequency range is 22.4–45 000 Hz with 32 filters. Furthermore, four weighting networks D, A, B, and C, and a linear network are supplied with detectors suited for wide-frequency measurements. Signal averaging is done by running exponential integrators with three selectable time constants. A time-coincident 13-oct spectrum as a function of time is available, either as a continuously changing spectrum or as a single instantaneous spectrum or as the highest level in each filter band during a given time. Total information-transfer time is 2 msec.
Ubiquitous Analyzers—Theory, Operation, and Performance
Authors: Bickel H. J. , Citrin A. , Vogel R.
Published: October 2005

Ubiquitous analyzers compute 10 000 to 50 000 spectral points per second using time-compression techniques. Analog input signals are band limited prior to sampling and quantization. Time series of 1500 nine-bit words are processed to yield 500 or more spectral points in 50 msec. Sampling takes place at 1.5×Nyquist frequency with a 300-kHz upper limit in current equipment. The width of the analysis range is one-third the sampling frequency, and the processing bandwidth is 1/500 the analysis range. Signal storage and time compression are carried out digitally, while filtering takes place in the analog domain. The filter shape is controlled by convolving the time series with a window function. Ubiquitous analyzers are building blocks in systems performing cross-spectrum analysis and correlation. Mean-spectral characteristics are obtained with a digital averager following spectrum analysis. For spectral-density measurements, absolute calibration is established in terms of volts2/Hz. The equipment offers a choice of estimating spectral density, using an rms-type detector, but superior dynamic range (better than 10 000/1) is realized with pseudo-rms detection.
Ribbon Velocity Micorphones
Authors: Olson Harry F.
Published: October 2005

A theoretical consideration of the performance of a ribbon-type velocity microphone has been carried out. This analysis is applied to two types of ribbon-type velocity microphones, namely, an ideal design and a commercial design. Both microphones cover the audio-frequency range with uniform response and directivity.
Foil-Electret Micorphone for Use at Low Infrasonic Frequencies
Authors: Sessler G. M. , West J. E.
Published: October 2005

Design and performance characteristics of a foil-electret microphone having high and constant sensitivity in the frequency range 10−3–104 Hz are presented, giving particular emphasis to the lower part of this range. The instrument is similar to the familiar audio-frequency foil-electret microphone [G. M. Sessler and J. E. West, J. Acoust. Soc. Amer. 40, 1433 (1966)]. The lower cutoff frequency is determined (1) electrically, by the combination of high capacitance of the microphone (typically 1000 pF for a system 5 cm in diameter) and high input impedance (1011 Ω) of the preamplifier used, and (2) mechanically, by the size of a leak in the back cavity of the microphone, necessary for the equilization of slow atmospheric pressure fluctuations. Absolute calibration of the microphone was carried out in the lower part of the frequency range (10−3–102 Hz) with a pistonphone and at higher frequencies with a reference method. The microphone responds linearly to sound pressures between 0.1 and 1000 μbar. The system is mechanically and electrically simple and rugged. Application of the microphone to the measurement of natural and man-made atmospheric disturbances is discussed.
Theatre-Type Loudspeaker Systems
Authors: Hilliard John K.
Published: October 2005

The use of loudspeakers for theatres and auditorium sound reinforcement is reviewed starting with designs used for the first sound motion pictures 40 years ago. The first standardized two-way loudspeaker system application began in 1936, followed by improvements in 1945. In 1969, a theatre-type two-way system was designed to incorporate the experience of their use to date. The objectives of the design were: (1) extended frequency range (30 Hz–12 kHz); (2) more uniform distribution (sectoral horn vs multicell horn); (3) lower distortion (shorter horn and larger throat); and (4) increased reliability (use of improved material over temperature range).
New Experimental Results with High-Conductance Ultrasonic Image Converter
Authors: Turner William R. , Render James M.
Published: October 2005

The high-conductance quartz ultrasonic image converter differs from those of the Sokolov type in that the scanned element is connected to the output termination by a high-conductance secondary electron path over which interaction can occur between the element and the termination. Conductance-bridge measurements over this path indicate a mushroom-shaped space-charge cloud with the path conductance set by the mushroom-head surface area and the ultrasonic resolution by the electron-beam diameter. A measured equivalent noise intensity of 6×10−6 W/m2 for operation at 2.5 MHz with a 400-kHz video bandwidth is evaluated in terms of stored-energy retrieval and internal-noise sources. The observed resolution approaching 20 lines/in. appears primarily set by electron-beam diameter rather than by conversion-plate thickness.
Acoustic Imaging with Crossed Linear Arrays
Authors: Wells Willard
Published: October 2005

The extension of acoustic holography to uncontrolled media outside the laboratory requires rapid scan of a large hologram surface. A system employing crossed linear arrays, one transmitting and one receiving, can perform an equivalent scan with maximum speed and minimum complexity. N receivers listen simultaneously while N transmitters pulse in rapid sequence. Thereby the system gathers N2 data (amplitude and phase), which constitute a virtual hologram. The interference fringes in the hologram are shifted slightly from those of conventional holography. This causes two or three aberrations, which are insignificant except in unusual cases, namely a rotation of the image field proportional to the transmitter pulse rate, a distortion with uncorrected optical reconstruction, and a diffraction effect at corners having sides parallel to the linear arrays. The figures show images formed by computer simulation only. In order of increasing complexity, these include images of point reflectors and then simple geometric shapes viewed at various angles. Both specular and diffuse reflecting surfaces are included, the latter being simulated by adding random numbers to the phase of the acoustic wave at each reflection point.
Determination of Ultrasonic Absorption Coefficient by Optical Holography
Authors: Alippi A. , Palmieri L.
Published: October 2005

A holographic method has been recently performed by the authors, which permits the separation of the light diffracted by an ultrasonic grating into all its optical moments, whose complete spectral distribution is achieved in the reconstruction process. Such a technique differs from normal holographical arrangements for the use, in the recording process, of a reference beam that contains a selected set of optical frequencies, bounded to the frequency of the ultrasonic field, which is set on the object beam [A. Alippi and L. Palmieri, Acustica 20, 84 (1968); 21, 104 (1969)]. The aforesaid spectral representation of optical momenta, which is much more significant than the usual diffraction spectrum, offers new investigation methods for the analysis of ultrasonic fields in transparent media. In the present paper, it is shown how the absorption-coefficient determination of ultrasonic waves can be achieved by study of the spectrum of the holographically reconstructed light moments diffracted by an ultrasonic pulse train and by their echoes reflected back in opposite direction and partially absorbed by the medium. Such a method, which permits one to separate the diffraction spectra relative to ultrasonic pulses traveling in opposite direction, does not require any translational movement of the light beam through the ultrasonic field.
An Inexpensive System for Live Stroboscopic Holographic Interferometry
Authors: Fryer P. A.
Published: October 2005

A simple system for live stroboscopic holographic interferometry is described. Particular attention is given to the light-saving techniques made necessary by the low-cost and therefore relatively weak lasers available. Time-averaged and stroboscopic methods are discussed, and a simple stroboscopic system is described. Finally, some techniques for altering the basic sensitivity of the method and for its application to the analysis of plate vibrations are briefly outlined.
Optical Analysis of Waves in Continuous Media
Authors: Clark J. A. , Durelli A. J.
Published: October 2005

Multiple-exposure holographic interferometry is combined with photoelasticity to obtain complete, direct, full-field determinations of dynamic stress distributions in two-dimensional problems. The method is independent of assumptions associated with theories of wave propagation. Three independent measurements are used: isochromatics, isoclinics, and isopachics (families of interference fringes that are measures of the difference, directions, and sum, respectively, of the principal stresses at each point). Isochromatics and isoclinics are obtained by synchronizing the (repeatable) loading of a model with a short-duration flash through a continuously variable delay circuit. Interference fringes observed when elements of a polariscope are placed on each side of the photoelastic model are photographed with a still camera. Isopachics are obtained with a form of holographic interferometer that has particular advantages for static and dynamic optical stress analysis (large field of view, automatic elimination of the effect of rigid-body motions of model). The method is applied to the study of: (1) flexural waves in a bar; (2) transverse waves in a prestressed bar; and (3) flow induced in a surrounding, birefringent fluid by flexural waves in a bar. The results are extended by the application of scaling laws to predict stresses in vibrating steel and nylon cables.
Modified Rhyme Test as a Tool for the Testing of Speech Perception in Classrooms
Authors: Strumpf F. Michael , Chillemi Vincent E.
Published: October 2005

The modified rhyme test was used as a subjective test to investigate the speech perception ability of normal-hearing listeners in a regular classroom situation. A preliminary investigation using the tests showed discrepancies that could not be accounted for. A thorough statistical analysis of the tests was undertaken. The main emphasis was on the construction of the tests, comparison between tests, and the subjective involvement of the test subjects. Modified rhyme tests were given to subjects in different classrooms and under various speech-level and background-noise conditions. The differences in the speech-perception scores were analyzed with regard to the location of the subjects within the room as well as the other variables listed.
Speech Intelligibility: A Model and an Experimental Study
Authors: Berman M. S. , Schultz M. C. , Tanner W. P.
Published: October 2005

Studies in speech intelligibility have been constrained by the inability to predict the result of any alteration in a communication system. The conventional measure of percent correct is inadequate in that it deals with only some portion of the data, and is variably influenced by subject response bias, and in other significant ways. This paper offers a model of the speech communication process arising from statistical decision theory and information theory. An experimental testing of the model was undertaken. Four trained subjects responded to frequency-filtered speech samples in noise from two message sets. The first contained 12 single words and the other comprised 36 three-word sequences. A priori predictions on maximum performance for both lists were calculated from a model based on signal detectability. Sequence results were predicted from scores obtained on the single words according to the same model. A posteriori predictions were attempted by use of percentage-correct scores and measures derived from information theory. The paper supports the model proposed. [Research supported by a grant from the Office of Naval Research presented to the Sensory Intelligence Laboratory at the University of Michigan.]
Effect of a Low-Frequency Band (240–480) Hz of Speech on Consonant Discrimination
Authors: Franklin Barbara
Published: October 2005

The Fairbanks rhyme test was filtered into two bands with 60–70 dB/oct attenuation—low-frequency band (LB) of 240–480 Hz and high-frequency band (HB) of 1020–2040 Hz. The average articulation score was 40% when the HB was presented at threshold to one ear. The articulation scores were significantly higher for the right than the left ear. The LB contains negligible information when presented alone, but the articulation score rose to 61% and 62% when added at 20-dB sensation level (SL) to the same and opposite ear as the HB, respectively. When the LB was added at 40-dB SL to the same ear, the articulation score dropped to 38%, but when added to the opposite ear, the score dropped only to 54%. When the LB was added at 40-dB SL to the same ear, the scores for the consonants in Group I—/p/, /t/, /k/, /f/, /s/, /m/, /n/, and /l/—did not drop as much as Group II—/b/, /d/, /g/, /w/, and /r/. The writer suggests that the multiple cues—bursts, friction, or nasal resonances—enabled the Group I sounds to maintain some identity despite the “masking” effect of the LB at high levels relative to the HB. [This paper is based on a dissertation submitted to the Graduate Faculty in Speech in partial fulfillment of the requirements for the degree of PhD, The City Univ. of New York, June 1969.—Dr. J. Donald Harris, Principal Advisor.]
Effect of Syntactic and Semantic Violations on Sentence Intelligibility
Authors: O'Malley Michael H.
Published: October 2005

A technique for measuring minor differences in the intelligibility of words in context was developed and used to measure the effect of violations of syntactic and semantic structure on intelligibility. Hypothetical analyses of English were drawn from transformational grammar and from analytic philosophy. These hypotheses about linguistic competence were converted to hypotheses about which one of a pair of sentences containing the same test word was more acceptable or “grammatical.” The average signal-to-noise ratio (S/N) at which the test word could just be recognized was found for each sentence. The difference between the S/N of the “good” and “bad” sentences in a pair was compared with the results from a questionnaire that asked for differential judgements of acceptability. In general, semantic violations did not affect intelligibility while grammatical violations did. Results are categorized according to the type of syntactic and semantic violation.
Dichotic and Monotic Simultaneous and Time-Staggered Speech
Authors: Lowe S. S. , Cullen J. K. , Thompson C. L. , Berlin C. I. , Kirkpatrick L. , Ryan J. T.
Published: October 2005

Twelve female normal listeners, all right-handed, heard rhyming pairs of (stop+/a/) nonsense syllables dichotically and monotically. Word onsets were simultaneous, then shifted by 15, 30, 60, and 90 msec. Each subject heard 600 pairs. Monotically, the lag-syllable discriminations were poor at all delays with differences leveling off at 30 msec (93% lead vs 19% lag). Dichotically, lag-ear discrimination was roughly 22% better for all lag times when the right ear lagged. [First found by Shankweiler and Studdert-Kennedy, personal communication.] Left-ear lag scores improved and overcame the right-ear advantage only after 30-msec delay. Total right-ear scores for entire dichotic portion of experiment (M=77%) exceeded total left-ear scores (M=66%) thus maintaining an over-all right-ear laterality effect. Thus, previous experimenters who allowed as much as 90-msec delay to be randomly distributed among their so-called “simultaneous pairs” might still have expected to find a right-ear laterality effect. [Supported in part by NINDS.]
Characterization of Breast Tissue by Ultrasonic Visualization Methods
Authors: Fry Elizabeth Kelly , Gibbons L. V. , Kossoff G.
Published: October 2005

With appropriate instrumentation, ultrasonic visualization provides a rapid, nondestructive method for obtaining cross-sectional pictures of breast, with the significant capability of detecting abnormalities of both large and small dimensions (a cubic millimeter of tissue or less). No cumulative effects are produced in the tissue by application of such methods, and changes in breast tissue over long periods of time can be followed. In the investigation reported here, a detailed ultrasonic visualization study was carried out on normal subjects, ranging in age from 20 to 70 yr and on subjects with specified pathologies. Excised breast tissue, both normal and pathological, was also examined by the ultrasonic method. One of the primary goals of this study is early detection of breast tissue conditions that may represent precursors to pathological developments. The instrumentation techniques applied included the incorporation of an on-line computer as an integral part of the experiment. [The work upon which this publication is based was performed under contract with the U. S. Public Health Service, Department of Health, Education, and Welfare. William J. Fry originated the over-all instrumentalism approach and in particular, the unique application of the computer to the ultrasonic visualization study of biological tissue, as used in this study. Professor Fry died prior to carrying out his planned experiments on breast tissue.]
The Barrier in Open-Office Planning
Authors: Hyde Jerald R.
Published: October 2005

The effectiveness of a barrier in open office planning is evaluated in terms of the total system of surrounding surfaces. Scale-modeling techniques utilizing an ultrasonic source have been used to determine the loss in sound isolation provided by a barrier between two adjacent spaces when reflective but potentially absorptive surfaces such as corewalls, ceiling lighting fixtures, and other barriers are in the proximity of the barrier. The importance of the orientation of source and barrier with respect to ceiling lighting systems is analyzed along with the importance of ceiling-tile absorption. The use of reflective panels to enhance isolation is discussed. Barrier effectiveness is also evaluated in terms of speech privacy and intelligibility criteria for a general case.
Acoustical Conditions in Open-Plan Classrooms
Authors: Kingsbury H. F. , Taylor D. W.
Published: October 2005

Measurements have been made of a number of acoustical parameters important to determining the perception of speech in open-plan classrooms. The measurements were made in an open-plan elementary school where in each cluster there are five separate classes conducted in undivided space. Measurements taken include decay rates, background and ambient levels, attenuation of sound with distance, and teachers' vocal effort. Based on these data, calculations are performed to indicate both intelligibility and privacy at the student's positions. Included also are tentative acoustical design guidelines for such classroom spaces.
Some Unexplained Phase Shifts in Axial Radiation from Direct-Radiator Loudspeakers
Authors: Allen Harry E.
Published: October 2005

While making virtual sound source measurements in an anechoic chamber on a stereo loudspeaker system with crossed cosine (ribbon) microphones, it was noticed that phase differences existed between the microphone outputs when only one loudspeaker was energized. This phase shift changed rapidly with frequency and the null axis shifted as much as 2° with a ±28-Hz change at 500 Hz. Since interaural phase relationship measurements are often made using loudspeakers as acoustic sources, the measurements to be reported in this paper should be of interest to workers in psychoacoustics.
Perception of Square-Wave and Sinusoidal-Wave Response from Direct-Radiator Subminiature Loudspeaker
Authors: Sebesta G. J. , Carlisle R. W.
Published: October 2005

The operation of a portable counter requires the audible perception of square-wave impulses covering the 300–3000-Hz band; weight and size limitations indicate the use of a reproducer weighing only a few grams; and safety to the ear precludes the use of a hearing-aid type ear insert. These specifications appear mutually contradictory unless it is noted that the rich harmonic content of square waves may make possible the identification of relatively low frequencies by perception of the harmonics. Thus, to perceive a 300-Hz signal it may be necessary only to hear actually a 600- or 1200-Hz sine wave. A practical solution is to utilize a hearing-aid type button receiver, with the fundamental resonance of the diaphragm and associated acoustical network located at as low frequency as possible, i.e., around 1200 Hz. Free-space measurements show response from below 1000 to above 4000 Hz. It is found experimentally that this meets the above requirements. Refinements on the systems will be described.
Plane-Wave Tube for Low Audio Frequency and Infrasonic Acoustic Measurements
Authors: Brouns Austin J.
Published: October 2005

A plane-wave tube was designed to measure microphone frequency response and polar response at frequencies as low as 1 Hz. The acoustic impedance presented at the end of an open pipe becomes vanishingly small as frequency decreases. Consequently, a planar cover set at the end of the pipe, having a specific acoustic resistance of ρc, provides the required nonreflecting termination. The cover was fabricated of layers of nonwoven cloth sandwiched between aluminum honeycomb. The upper-frequency limit of the plane wave tube is determined approximately where λ equals the tube diameter. The lower-frequency limit is determined only by microphone sensitivity. Two tubes were built. One tube was 10 ft long × 30 in. diameter, used four large woofers as sound sources, with a 35-Hz upper-frequency limit. Excellent polar responses of a cardioid microphone were measured at 1 Hz. Careful measurements were required to adjust the termination resistance to ρc.
The Acoustic Force on a Liquid Droplet in a Stationary Sound Field
Authors: Crum Lawrence A.
Published: October 2005

A stationary sound field exerts on a spherical inclusion a net acoustic force that tends to propel the sphere toward the nodes or antinodes of the standing wave system. With sufficient acoustic pressure amplitudes, it is possible to trap certain liquid droplets near the antinodes. Measurements are presented of the acoustic pressure amplitudes required to trap small, individual liquid droplets of various liquids near a pressure antinode of a stationary sound field in a cylindrical container filled with water. The liquids investigated were toluene, hexane, benzene, carbon tetracholoride, chlorobenzene, and paraldehyde. The driving frequency was near 41.7 kHz, the droplet size on the order of 500 μ, and the wavelength in the a direction about 8 cm. It was found that pressure amplitudes on the order of five bars were required to trap most droplets. The experimental results agree well with theory if the compressibility of the liquid droplets is taken into consideration. [Work supported by the Office of Naval Research.]
Diffraction about a Rigid Cylinder in a Reverberant Acoustic Field
Authors: Kasper P. K. , Bixler O. C.
Published: October 2005

The existence of an interference pattern about a cylinder exposed to a randomly incident acoustic field has been established analytically. [R. V. Waterhouse, J. Acoust. Soc. Amer. 35, 1610–1628 (1963)]. A series of experiments has been performed to investigate this phenomenon for the case where the wavelength of the incident waves is much smaller than the circumference of the cylinder. The experiments were performed in a reverberant acoustic field using a hard-walled cylindrical surface. The measured relationship between cylindrical radius, wavelength of excitation, and sound pressure level at varying radial distances is presented. The results are qualitatively compared with a calculation based on Waterhouse's solution for the diffraction around a cylinder in a two-dimensional field.
An Experimental Observation of Nonlinear Pressure Resonance in a Piston-Driven Column of Air in a Closed Pipe
Authors: Cruikshank D. B.
Published: October 2005

W. Chester [J. Fluid Mech. 18, 44–66 (1964)] predicted the pressure waveforms generated by a piston in a closed acoustic resonance tube. To check these predictions, an experimental apparatus, consisting basically of a 5-ft. 8-in. cylindrical, air-filled pipe, capped at one end, and fitted with a movable piston at the other end, has been constructed. The piston is driven sinusoidally by an electrodynamic shaker, and pressure-waveform measurements are made with a microphone at the rigidly capped end of the pipe. Good qualitative agreement between the shapes of experimental and theoretical waveforms is found at high piston-displacement amplitude. However, about resonance a pressure-amplitude asymmetry, apparently not predicted by theory, is experimentally observed. The pressure response curve of the experimental system is investigated and shown to be asymmetric, i.e., skewed toward higher frequencies like the response curve of a nonlinear, hard-spring oscillator. [This study was supported by the Mechanics Division, AFOSR, and by ONR under a CNA subcontract.]
Second-Harmonic Generation in Plane-Piston Beams
Authors: Rogers Peter H. , Williams A. O.
Published: October 2005

A perturbation method is used to calculate the second harmonic (“H2”) that is generated by nonlinear processes in the first-harmonic (“H1”) beam from a circular plane-piston source of radius a, in a rigid baffle, radiating at wavelength λ into an essentially dissipationless fluid. Williams et. al [J. Acoust. Soc. Amer. 37, 1181(A) (1965)] calculated H2 along the beam axis, z. We have evaluated H2 off-axis (0⩽r⩽a) for the fairly near field, with approximations valid when a/λ ≈ 10–40. For a/λ ≈ 18, at axial distances 5a≲z≲15a, predictions agree well with measurements [Gould et al., J. Acoust. Soc. Amer. 40, 421–427 (1966)]. As a/λ → ∞, H1 approaches a cylindrically collimated beam of plane waves with constant amplitude, all “structure” being within an infinitesimal paraxial region; H2 approaches cylindrically collimated plane waves with amplitude proportional to z. Although both results are often assumed in practice, neither holds accurately below frequencies so high that absorption must be overwhelming. [Supported in part by U. S. Office of Naval Research.]
Computerized Study of Finite-Amplitude Traveling Waves Confined to a Duct
Authors: Coppens Alan B.
Published: October 2005

Manipulation of an infinite set of coupled nonlinear differential equations representing a one-dimensional model of finite-amplitude acoustic processes occurring in a rigid-walled duct (wherein boundary-layer effects at the duct walls are the dominant loss mechanism) yields a form amenable to a Runge-Kutta iteration method performed on a computer. The results provide practical evaluation of the limitations of existing perturbation solutions and allow extension of prediction of harmonic distortion and other nonlinear effects from the regime α1x < 1, Mb/δ1≪1 to the regime 0⩽α1x < ∞, Mb/δ1≲1, where α1 = 12δ1ω/c0 represents the attenuation constant of the fundamental frequency component of the waveform in the linear (infinitesimal-amplitude) limit x the distance from the source, M the peak Mach number of the source, ω the angular frequency of the source, b = 1 +12 B/A, B/A the parameter of nonlinearity of the fluid, and c0 the phase speed in the limit b = δ1 = 0. Waveform predictions have been made and appear to be consistent with experimental observations of other workers.
Simulation of the Measurement Phase of an Automatic Speaker Recognition System
Authors: Wolf Jared J.
Published: October 2005

This paper describes an investigation of an efficient approach to acoustic measurements (feature extraction) for speaker recognition motivated by known relations between acoustic output and vocal tract shapes and gestures. Rather than make general measurements over the extent of an utterance, only significant features of certain selected segments are used. In this study, these segments were located manually. A speaker identification experiment was performed, using seventeen measurements such as fundamental frequency and features of vowel and nasal consonant spectra. A computationally simple linear classification procedure was used, and the test data was kept independent of the design data. No errors were made in identification of the speaker for 210 test “utterances” by 21 adult male speakers. Procedures for evaluating speaker-separating ability of individual measurements and intermeasurement dependence are described. [This research was supported in part by the National Science Foundation, Air Force Cambridge Research Laboratories, and the National Institutes of Health.]