bluuebunny/crossref_metadata_2025 huggingface dataset:
Threshold Shift in the Chinchilla from Daily Exposure to Noise for Six Hours
Authors: Saunders J. C. , Mills J. H. , Miller J. D.
Published: May 2012

Chinchillas were trained for behavioral audiometry and then exposed to a schedule of 6 h of noise and 18 h of quiet for a nine-day period. The thresholds at 0.5, 2.0, 5.7, and 8.0 kHz were measured immediately before and after each exposure. The decay of threshold shift after the ninth day was followed until stable thresholds were again observed. This procedure was repeated at six levels (57, 65, 72, 80, 86, and 92 dB) of an ocatve band of noise centered at 4.0 kHz. The threshold shift measured after 4 min of quiet appears to reach asymptote (ATS4) after the first or second exposure. ATS4 increases with the level of the octave-band noise for daily 6-h exposures with the same slope as does ATS4 for continuous exposures. For frequencies exhibiting the greatest loss (5.7 kHz), ATS4 increases 1.7 dB for every decibel increase in the noise, if ATS4 is greater than 10–15 dB. The decay of TS was related to the level of the noise and, thus, the amount of ATS4. For exposures of 57 and 65 dB, the decay of TS during the 18-h period of quiet was nearly complete. The exposures at 72 and 80 dB required three to five days for complete recovery, while those at 86 and 92 dB were very slow and not complete with average values of PTS of about 6 and 13 dB, respectively.
Acoustic Trauma in Monkeys Related to the Frequency Spectrum of the Noise
Authors: Stebbins W. C. , Moody D. B. , Coombs S. , Johnssom L. G. , Clark C. S. , Hawkins J. E.
Published: May 2012

Old World monkeys were exposed to octave-band or wide-band noise at 117–120 dB SPL, 8 hours daily, five days per week for four weeks. The octave bands were centered at 500, 2000, 4000, or 8000 Hz. Thresholds for frequencies 63–40 000 Hz were measured daily before, during, and for one month after exposure, by the staircase method, using operant conditioning procedures with positive reinforcement. After the final threshold measurements the temporal bones were fixed and the inner ears examined by microdissection and phase-contrast microscopy. Maximum TTS, usually attained on the first day of exposure, ranged from 60 to 100 dB; PTS, from 40 to 60 dB. Both temporary and permanent loss involved at least two or three octaves and for the most part were greatest at, or within the octave above, the center of the exposure band. Hair cell counts showed reasonable correspondence between the location, severity, and extent (5–12 mm) of outer hair cell loss and the degree of PTS, in accordance with the place principle. In addition, most animals showed complete loss of outer and inner hair cells at the extreme basal end, usually correlated with a hearing loss for the highest frequencies. [Research supported by grants from NIH.]
Shallow Water Bottom Reverberation under Downward Refraction Conditions
Authors: Cole Bernard F. , Podeszwa Eugene M.
Published: May 2012

In 1965, some propagation loss and reverberation level measurements were performed under downward refraction conditions in a location south of Long Island. The interpretation of the propagation loss results was described in a previous paper [J. Acoust.Soc. Am. 41 (1967)]. This paper presents the reverberation level measurements collected during those trials, and reduces these measurements to scattering strength values by considering the details of the propagation to and from the bottom. The results are shown to be similar to those which Urick [J. Acoust. Soc. Am. 48, 129(A) (1970)] derived by ignoring the details of the propagation paths to and from the scatterets. Finally, the manner in which the downward refraction conditions facilitate the general gathering of bottom scattering strength values for shallow water areas is discussed.
Estimation of Bottom-Bounce Bearing Errors from Ocean Bottom Statistics
Authors: Perl Robert
Published: May 2012

The bearing error obtained from a bottom bounce sonar is proportional to the bottom slope in the direction perpendicular to the line of sight between the source and the target. Therefore, it is necessary to know the variance of the bottom slopes in order to estimate the magnitude of the bearing errors to be expected in a given ocean region. The bottom slopes can be completely described statistically by their wavenumber spectrum, which is simply related to the spectrum of the bottom depth fluctuations obtained from fathometer data. The slope spectrum represents the variance of slope per unit bandwidth, so that integration of the slope spectrum yields the total slope variance. For the purpose of estimating bearing errors, it is necessary to cut off the slope spectrum integration at a wavenumber inversely proportional to the width of the first Fresnel zone, because scattering from outside this region makes up a negligible portion of the measured return signal. Typical slope spectra in various regions will be presented. [Supported by Navy Science Assistance Program.]
Acoustic Method for Determining Current
Authors: Stall-Worth L. A.
Published: May 2012

Previous studies by Stallworth and Jacobson [J. Acoust. Soc. Am. 48, 382–391 (1970); 52, 344–355 (1972); S3, 332(A) (1973)] have shown that acoustic propagation from one fixed point to another is affected by bulk motion of the fluid between those points. The principal effect is on the acoustic travel time. This effect can be exploited to infer current from acoustic measurements. An error analysis indicates that existing instruments are capable of measuring currents to within ±0.05 cm/sec between points 100 m apart. A system is proposed for current measurement when the sound speed is spatially variable. Simplifications are possible when the current direction is known and/or the sound speed is constant.
Diffusion versus Other Properties of Sound Field
Authors: Tichy Jiri
Published: May 2012

The concept of one diffuse sound field has been created in order to define idealized sound field conditions. During several decades, attempts have been made to find a method which would make it possible to measure the field diffusion with sufficient reliability and accuracy. Although the perfectly diffuse field should be measurable by means of quantities such as autocorrelation or statistical distribution of amplitudes, there is no way or scale to express a “degree of diffusion” of some real sound fields. Therefore, the whole concept of diffusion should be revised. New data are presented on the autocorrelation properties of the sound fields in enclosures, and their relations to the statistical distribution of pressure amplitudes are presented. An attempt has been made to find the relation to sound field diffusion.
History of the Methods of Obtaining a Diffuse Field in Reverberation Rooms at Johns-Manville
Authors: Shippee E. D.
Published: May 2012

Johns-Manville was a pioneer in the measurement of sound, including sound absorption coefficients in a reverberation room. The evolution from early test methods in which pure tones were generated in a non-rectangular room to current methods with broad bands of random noise and stationary and moveable vanes forms the basis for an interesting study.
Angular Distribution of Normal Modes
Authors: Sepmeyer L. W.
Published: May 2012

The results of a computer investigation of the angular distribution of the normal modes of vibration of rectangular rooms is reviewed. The importance of angular distribution for several specific types of room uses is discussed.
Dispersion of Flexural Elastic Waves in Honeycomb Sandwich Panels
Authors: Thompson R. B. , Alers G. A. , Thompson D. O. , Tennison M. A.
Published: May 2012

Honeycomb sandwich panels are highly anisotropic, layered media predicted to have unique dispersion characteristics for flexure wave frequencies above a few kilohertz. The phase velocity of flexural waves traveling along a l-in.-thick honeycomb sandwich panel has been experimentally determined from 170 Hz to 50 kHz using three techniques: measurement of resonant frequencies of beam-shaped samples in forced vibration, measurement of nodal spacing in standing-wave patterns on beam-shaped samples, and measurement of the change in time delay of a particular phase feature of a wave packet as a function of propagation distance in large plate samples. The data are in good agreement with two models, a plate theory and an elasticity theory, each of which treats the core as a continuum. Above SO kHz, the predictions of the two models diverge and the experimental phenomena become more complex. A brief description of these results is given.
The Effects of Psychological Stress on Speech: Literature Survey and Background
Authors: Papçun George
Published: May 2012

The normal contraction of voluntary muscle is accompanied by a slight oscillation at approximately 10 Hz. This oscillation is known as physiological tremor. The nature and source of physiological tremor and its relation to psychological stress is examined in this paper. The functioning of a device to measure psychological stress from speech depends on three propositions, which will be considered: (1) The oscillation occurs in the muscles of the vocal apparatus during speech: (2) the oscillation is manifest in the acoustic signal of speech; (3) the oscillation is attenuated or modified by psychological stress; (4) the oscillation and changes in it can be detected, displayed, and evaluated. An attempt is made to assess the probable acoustic effects of tremor in various muscles and groups of muscles during speech. The following questions will also be addressed: (1) What is the linguistic significance, if any, of physiological tremor? (2) In what ways may the detection of physiological tremor be of use in speech research? (3) Can physiological stress and psychological stress be distinguished in their effects on tremor in speech? (4) Can physiological tremor be modified by volition or by linguistic phenomena, e.g., laryngealization?
Physiologic Correlates of Acoustic Correlates of Psychological Stress
Authors: Shipp Thomas , McGlone Robert E.
Published: May 2012

A volunteer young adult male subject was interrogated during part of an experimental procedure studying phonation. Hooked-wire electrodes were in place in laryngeal muscles. Simultaneous audio and physiological recordings were obtained of the subject's responses to the interrogation questions. Playback of the audio recordings through a Dektor PSE-1 often showed a differential pen deflection indicating “high stress levels” when the subject was knowingly fabricating his responses. Unprocessed EMG tracings obtained from the cricothyroid and thyroarytenoid muscles associated with the answer are shown along with f0 and the acoustic signal.
Laboratory Evaluation of Absorptive Silencer Performance
Authors: Blanck M. W.
Published: May 2012

The recently published ASTM E477 “Laboratory Standard Method of Test for Duct Liner Materials and Prefabricated Silencers for Acoustical and Airflow Performance” provides a consensus procedure for the measurement of insertion loss, airflow-generated noise, and pressure drop of air conditioning silencers. Similar test procedures have been in use since 1966 that yielded reproducible test results between laboratories. Round-robin data indicated that there was a need for a single test method which would eliminate small variations in testing procedures between laboratories. As in most laboratory tests, the silencer is tested in a duct location not normally found in actual usage. The acoustical consultant or mechanical engineer should, therefore, be aware that the laboratory data are for optimum conditions. The insertion loss may vary in actual applications, owing to different duct configurations and duct impedances. Pressure drop will normally be higher because ideal silencer entrance and exit conditions are only found in a long straight duct configuration.
Acoustical Characteristics of an Open-Ended Duct with Flow
Authors: Ingard Uno
Published: May 2012

The acoustical characteristics of an open-ended, rigid-walled duct carrying flows with mean velocities up to half the speed of sound have been studied. The pressure reflection coefficients from the upstream and downstream ends of the duct have been measured, and the results have been used in the evaluation of the Green's function for the duct. The bandwidths of the duct resonances have been determined as a function of the Mach number, and it is demonstrated that the resonances practically disappear at sufficiently high Mach numbers. The steady-state pressure distribution in a duct from a source inside the duct is measured, as well as the response of the duct to an external sound source. The results are discussed in the light of calculated results. [This work was supported by the U.S. Navy (Office of Naval Research) by Contract N00014-67-A-0204-0019.]
Space-Time Structure of Acoustic Propagation in Ducts in the Presence of Shear Flow
Authors: Mikhail M. N. , Abdelhamid A. N.
Published: May 2012

The effects of shear flow on the modal phase velocity, the group velocity, and the cutoff frequencies of acoustic modes propagating in ducts are studied analytically. The convection effect of the shear flow is found to be equivalent to the convection effect of a uniform mean flow with some effective Mach number. Using the effective Mach number, the uniform mean flow dispersion relation can be generally used to express the relation between the space-time parameters for any shear flow Mach number distribution. Acoustic duct modes which may be expected to propagate under the assumption of uniform mean flow will decay because of shear flow effects. The calculated propagation constant of different modes propagating upstream or downstream in annular, circular, or two-dimensional ducts are compared with all available data calculated by time-consuming sophisticated techniques and published by previous investigators. The comparison shows an excellent agreement. By using the effective Mach number to obtain the propagation constant, the solution of the sound field in the duct—and thus the refraction effects of the shear flow—becomes a simple matter of integrating an ordinary differential equation. [Research supported by National Research Council of Canada.]
Reflection and Transmission of Sound from a Duct with a Closing Aperture Carrying a Compressible Subsonic Flow
Authors: Davis Sanford S.
Published: May 2012

The effect of an aperture on an impinging plane wave in a duct is extended to the case where the duct carries a compressible mean flow. The effect of the mean flow is to induce the closing mechanical impedance, Z1 [ = (duct acoustic pressure at aperture) × (duct area)/ (duct acoustic velocity at aperture)] to have a significant resistive component in addition to the reactive component due to the “attached mass” effect. The effect of the reactive load on the aperture is shown to be especially important for large contraction ratios n [ = (duct area)/(aperture area)]. Of special interest is the acoustic particle velocity at the exit plane of the aperture. This is the “piston velocity” which drives the spherical acoustic waves in the farfield. The effect of aperture geometry on the piston velocity is established and a criterion for minimum acoustic radiation is presented. The experimental arrangement is described for measuring the piston velocity with a hot-wire anemometer. Measurements of piston velocity against jet Mach number show good agreement with theory.
Detection of Correlations between Pulsed Visual, Vibrotactile, and Auditory Signals
Authors: Pollack Irwin
Published: May 2012

Correlation detection is possible within the auditory modality alone, or within the visual modality alone, at sampling periods less than 1 msec (or even lower). Correlation detection is possible between the modalities, but only at substantially longer periods, presumably reflecting some form of central integration of switching time. Such switching time is not invariant with modality: best correlation detection is achieved with auditory and visual presentation; worst with visual and tactile; and intermediate with auditory and tactile.
Residue Pitch as a Function of the Frequency Spacing between Components
Authors: Patterson Roy D.
Published: May 2012

Residue pitch was determined for stimuli in which the frequency spacing between the component sinusoids was 100, 200, or 400 Hz, to ascertain whether the pitch shift of the residue was strictly proportional to the frequency spacing between the components. The stimuli were sets of six or 12 equal-amplitude sinusoids. The position of the set was varied throughout the frequency range in which the residue was audible. The pitch shift of the residue showed a disproportionate increase with frequency spacing for stimuli composed of low-frequency components. As the position of the set increased, the effect of frequency spacing decreased and once the lowest component in the stimulus was five or more times the frequency spacing between components, the effect of frequency spacing was negligible. [Research supported by the National Institutes of Health, Public Health Service, U. S. Department of Health, Education and Welfare and by a research grant awarded to the Center for Human Information Processing, UCSD.]
Periodicity Pitch Perception of Hearing-Impaired Listeners
Authors: Purvis George O. , Brandt John F.
Published: May 2012

Four groups of listeners matched the pitch of sinusoids to the pitch of ac pulse trains with pulse repetition frequencies of 150 and 250 located at center frequencies of 2000 and 4000 Hz. Group 1 had normal hearing; group 2 had low-frequency sensorineural hearing losses with normal hearing above 1000 Hz; group 3 had normal hearing below 2000 Hz and steep high-frequency sensorineural hearing loss; and group 4 had normal hearing below 1000 Hz with gradually increasing sensorineural hearing loss. The normal-hearing listeners had no difficulty perceiving the periodicity pitch. Hearing-impaired listeners presented complex patterns interacting with sensation level but, in general, could not detect the waveform periodicity as pitch related. The data support experiments that suggest the basal portion of the cochlea is responsible for the detection of periodicity pitch, although the hearing-impaired listeners did use high-frequency place information in pitch recognition.
Hearing Aid Performance Controls Suggested by Pure-Tone Masking
Authors: Haggerty John W.
Published: May 2012

At high intensities of sound, such as hearing aids deliver, the well-known pure-tone masking phenomenon limits the complexity of patterns encoded and transmitted by the normal and impaired hearing senses. These elementary masking considerations can be applied to evaluating hearing aids. In the domain of maximum performance of hearing aids [the so-called “saturated gain“ or “maximum power output (MPO) versus frequency“ curves], the typical hearing aid deviates considerably from optimal. Pure-tone masking phenomena dictate that the MPO/frequency profile be sloping upward with no large peaks; but the typical aid's MPO/ frequency profile slopes downward with increasing frequency and contains objectionable peaks. The MPO/frequency profile is of course independent of the nonsaturated acoustical gain curves, and is in fact established by independent (inductive and inertial) electroacoustic elements. The typical hearing aid cannot be adjusted to control either the intensity or the slope of the MPO/frequency curve; and these parameters are infrequently specified in aid prescriptions. This uncontrolled situation leads to aids that can be painful and/or unintelligible for complex sounds like music or speech-in-noise. In addition to existing controls on acoustical gain/frequency parameters, most hearing aids should incorporate smoothly adjustable controls for both MPO/frequency upward slope rate and MPO/ frequency absolute intensity.
Experiments on Phase-Reversed Shock Propagation and Parametric Generation
Authors: Mellenbruch L. L. , Muir T. G.
Published: May 2012

Insertion of a pressure-release baffle in the path of a shock wave effects a 180° phase change which reverses the distortion process in the reflected waveform. Energy contained in the harmonic components of the original shock then returns to the fundamental with further propagation. The dissipation of energy by absorption at the harmonic frequencies is therefore minimized. This allows one to generate higher sound pressure levels at remote field points and to circumvent the limits of acoustic saturation. This process would also appear to improve parametric conversion efficiency. Theory for this effect is presented in a companion paper by Lockwood. Experiments on these effects were conducted in fresh water with a planar polystyrene reflector in-sonified by a beam of primary frequencies in the neighborhood of 440 kHz, at source levels up to 133 dB re 1 μbar at 1 yd. Measurements of propagation curves and of the amplitude responses at a distant field point were made for single and multifrequency parametric excitation. With some exceptions, the results support the aforementioned contentions. [This work was supported by the U. S. Navy Office of Naval Research.]
Narrow-Beam Sound Fields in a Sand Sediment
Authors: Thompson L. A. , Muir T. G.
Published: May 2012

The sound field in a sand bottom resulting from narrow-beam insonification by parametric sources located in an overlying water column was studied as a function of the transmitted frequency, grazing angle, and depth of penetration. This study was conducted in a large test tank filled to a depth of 3 ft with unwashed, fine river sand. A parametric transmitting array was used to generate a low-frequency narrow-beam field. The narrow beamwidth and absence of minor lobes which are characteristic of parametric transmitting arrays were necessary to achieve the resolution and reverberation reduction that allowed this experiment to be performed in a tank. Beam-widths of 1° and 2° at 5–20 kHz were achieved using a line-in-cone transducer. Sound fields in the bottom were measured by plotting the output of a spherical hydrophone buried in the sediment as a function of the position and orientation of the beam on the bottom. This was done for three grazing angles (15°, 28°, and 38°), three transmit frequencies (5, 10, and 20 kHz), and three hydrophone depths (3, 6, and 12 in.). Re-radiation (with spreading) of the beam in the bottom was noted and the expected refraction of the beam at the bottom interface (as predicted from plane-wave theory) was not observed. [This work was supported by Naval Ship Systems Command.]
Travel Time Functions on the Basilar Membrane
Authors: Greenwood D. D.
Published: May 2012

Analysis of Rhode's data (1971) on basilar membrane response in the squirrel monkey has permitted the phase data to be fitted by empirical functions which give cumulative phase, or travel time, for tones of different frequency to the given position. These functions were transformed, by means of two auxiliary functions, to express the travel time of a given tone to any point on the membrane. Calculations of travel times to positions of maximum amplitude closely fit estimates of travel times derived from VIIIth nerve units by Anderson et al. (1971). With scale changes in constants, the functions can be applied to other species. Calculations quite closely agree with the apical phase data of Békésy for man. They also agree with Kohllöffel's (1972) relative phase curves from the basal half of the guinea pig cochlea, giving a phase of about 4π at maximum amplitude. Considerable agreement is found with some of the cochlear microphonic phase measurements of Eldredge and others in the guinea pig. The agreement observed suggests that the functions may be useful in relating physiological and psychophysical data from different species, and implicit support is given to the idea of fairly precise scale relations among some species.
Critical Bandwidth in Other Species
Authors: Greenwood D. D.
Published: May 2012

The hypothesis was offered some years ago (Greenwood, 1961) that critical bandwidth in man was an exponential function of distance on the basilar membrane. Integration of the function yielded directly a frequency-position curve fitting Békésy's data. Thus critical bandwidth in man was apparently proportional, and if distance was scaled in millimeters, numerically equal, to the derivative of the frequency-position function. It was unlikely, however, that critical bandwidth would correspond to the same distance in species with cochleas of different sizes. Scale relations between frequency-position functions of a few species, and between displacement envelopes in four species (Greenwood, 1962), suggested that critical bandwidth might correspond to scale-related distances, implying changes among species in the constant of proportionality to the derivative of the frequency-position function. Based on a 1-mm distance in man, some unpublished calculations of scaled distances were made for other species. Subsequently, a revised CB function was suggested for man (Greenwood, 1971) in which critical bandwidth corresponds to 1.25 mm. Based on this distance, scale-related functions are suggested for cat, squirrel monkey, and guinea pig in which critical bandwidth corresponds, respectively, to distances of about 0.78, 0.71 +, and 0.61 mm. These values may be related to distance measures derived from physical and physiological data in those species.
A Mathematical Model of the Mechanics of the Cochlea
Authors: Lien M. D. , Cox J. R.
Published: May 2012

A mathematical model has been developed for the mechanics of the cochlea that includes the effects of viscosity, the three-dimensional motion of the cochlear fluid, and the solid mechanics of the basilar membrane. Beginning with basic hydrodynamic equations for an incompressible viscous fluid, and through the use of a Green's function with two source points, an integral equation relating the pressure difference across the membrane to the motions of the stapes and membrance is derived. Another equation relating the membrane motion and pressure difference across it is obtained from basilar membrane solid mechanics. Combining these equations, a second-order differential equation is obtained which with its boundary conditions describes the pressure difference and thence membrane motion as a function of stapedial motion. Amplitude of the basilar membrane displacement, its maxima, locations of its maxima, and impulse propagation time along the membrane computed from the model are found in rough agreement with measurements of Békésy, Johnstone et al., and Rhode. Phase characteristics have features that are similar to those obtained from Moss-bauer measurements, cochlear microphonics and auditory nerve fiber responses. [Supported by N1H Grant RR 00396.]
A Mode of High-Frequency Acoustical Signal Encoding Suggested by Nerve Model Array Studies
Authors: Hag-Gerty John W.
Published: May 2012

Another detailed process for encoding high-frequency auditory patterns into nerve arrays is specified. This fire-ordering process models (by computer simulation) many cell-firing phenomena reported for single units of cochlear ganglia or VIIIth nerve fibers—particularly for those high frequencies at which phase coherence is obscured. Lifelike features of this encoding process include the following: (1) the basic simulation cell incorporates time con-slants modeling microchemical transport and cumulation delays; (2) the array uses electrotonic lateral inhibition; (3) dynamic properties of the fire-ordering seem to correlate with such natural sensory properties as large dynamic range and fast intensity normalization, sharp threshold of encoding, recruitment and upper frequency incompetence with decay of nerve population density, signal encoding mode {ordered wave-fronts across fiber arrays) that is orthogonal to background noise, little energy requirements for encoding; (4) fire-ordering encoding arrays display behavior reported for single units at low frequencies: periodicity encoding or phase coherence, pure-tone masking phenomena, and even the narrow quiescent notch as intensity increases at characteristic frequency, etc.; (5) this interesting fire-ordering process encodes high frequencies into arrays of frequency-limited fibers as angle-of-wavefront propagation. Spatial edge direction is a pattern feature already known to be extracted by the vertebrate visual pathway.
The Effect of Delayed Channel on the Perception of Dichotically Presented VC Syllables
Authors: McCormick Colin , Porter Robert J.
Published: May 2012

Subjects were asked to identify pairs of dichotically asynchronous (by 0–180 msec) vowel-stop consonant syllables (VCs). Results were compared to those obtained in a previous study in which the essentially temporally reversed versions of these syllables (i.e., CVs) were used [R. J. Porter, Jr., J. Acoust. Soc. Am. 54, 286(A) (1973)]. As has been found in the case of CVs, the lagging member of the VC pair was more accurately identified than was the leading (“lag effect”). An interesting aspect of the VC data was, however, that the maximal lag effect was seen at a 90-msec syllable onset asynchony rather than the 60-msec observed for CVs. These results extend the generality of the lag effect and suggest that the processing of VCs may have a different temporal course than that for CVs. [Work supported in part by NIH Grant Funds.]
The Effects of Practice on the Perception of Dichotic Pairs of CV Syllables
Authors: Troendle Roger , Porter Robert J. , Berlin C. I.
Published: May 2012

Ten subjects participated in eight weekly dichotic testing sessions. During each session subjects received 120 random dichotic pairs of the CV syllables [ba, da, ga, pa, ta, ka]. Subjects were asked to identify both syllables, indicating which syllable was clearer. The magnitude of the right-ear advantage (REA), which is typically found under such listening conditions, was measured in several ways and found to vary only slightly over sessions; overall accuracy of identification for both ears, however, was found to increase to an asymptote after about five sessions (600 trials). The observed stability of the REA suggests it to be a reliable measure with as few as 120–240 trials. Also discussed are (1) the implications that these results have for models explaining the REA and (2) some interesting individual variations from the group results. [Work supported in part by NIH grant funds.]
The Effect of Varied Bandwidth, Signal-To-Noise Ratio, and Intensity on the Perception of Consonant-Vowels in a Dichotic Context: Additivity of Central Processing
Authors: Thompson Carl L. , Samson Diane , Cullen John K. , Hughes Larry F.
Published: May 2012

Normal subjects were presented simultaneously aligned consonant-vowel stimuli in three forced-choice dichotic experiments in which the information content of one signal was changed by (1) varying the intensity, (2) low-pass filtering, and (3) alterations in signal-to-noise ratios. The results of all three experiments were complementary. As signal characteristics were varied to produce a reduction of information to one ear, and thus a decrement in performance, an increment in performance of the unaltered ear was observed. The trade-off ratios of decrement and increment were such that total performance (summed ear scores) remained virtually constant. Dichotic ear effects (e.g., right ear outperforming left ear) appear to be orthogonal to this phenomenon. These observations indicate that perception of dichotically presented consonant-vowel depends upon the central additivity of information from two quasi-independent channels, overall performance being limited by the capacity of the central processor. [Work supported by NIH.]
Inter- and Intra-Subject Reliability for a Dichotic Listening Task
Authors: Ryan W. J. , McNeil M.
Published: May 2012

The purpose of this investigation was to assess the degree of reliability exhibited by normal subjects on a dichotic listening task. Sixty pairs of CV syllables were dichotically presented to each of 25 listeners. A two-response forced-choice design was employed ; subjects were required to write their responses. An identical task was performed by each subject approximately two weeks after the first presentation. In addition to the expected average right ear preference, a high degree of listener reliability was exhibited in a number of ways. Significant correlation coefficients and nonsignificant t values for right ear, left ear, right-left difference, and POE test-retest scores verified the impression that listeners are reasonably stable in their responses to dichotic stimulation.
Parallel Processing of Auditory and Phonetic Information in Speech Perception
Authors: Wood Charles C.
Published: May 2012

Previous experiments using a variety of techniques have distinguished between separate auditory and phonetic levels of processing in speech perception. For example, Day and Wood [J. Acoust. Soc. Am. 51, 79(A) (1972)] showed that an auditory dimension of synthetic syllables could be processed independently of a phonetic dimension, but that the phonetic dimension could not be processed independently of the auditory dimension. Two models of auditory and phonetic processing appear to be consistent with these results: (1) a serial model in which auditory information would be processed at one level followed by the processing of phonetic informational a subsequent level; (2) a parallel model in which the processing of auditory and phonetic information could be initiated and proceed simultaneously. The present experiment attempted to distinguish empirically between these two models. Subjects identified either an auditory dimension (fundamental frequency) or a phonetic dimension (place of articulation of the consonant) of synthetic consonant-vowel syllables. When the two dimensions varied in a completely correlated manner, reaction times were significantly shorter than when either dimension varied alone. These results are consistent only with a model in which auditory and phonetic information can be processed in parallel.
Factor Analysis of Voice Perception
Authors: Colton R. H.
Published: May 2012

Thirty scales from the semantic differential were utilized to investigate the dimensions underlying voice perception in 10 normal male and 10 normal female speakers. Nineteen observers rated the concepts of normal and normal voice quality in addition to a sentence read by the 20 speakers. A principal components analysis with varimax rotation was performed on the data. The results revealed five factors, accounting for approximately 63% of the variance. Factor I accounted for 20% of the variance and had high loadings on such scales as passive/active, still/vibrant, and vigorous/ feeble. Factor II accounted for 18% of the variance and loaded on pure/impure, smooth/rough, and choked/free. Factor III accounted for 11% of the variance and loaded on thick/thin, dark/bright, and heavy/light. Factors IV and V each accounted for 7% of the variance and loaded on scales such as youthful/mature, new/old (Factor IV), dry/wet, and cold/ hot (Factor V). The D metric was utilized to portray the distances between the concepts normal and normal voice quality and the 20 speakers. Further analysis is currently in progress utilizing 154 additional observers.
Perception of Brief Stimuli that Resemble Rapid Formant Transitions
Authors: Klatt D. , Shattuck S. R.
Published: May 2012

One problem for the child who is acquiring language is the lack of acoustic similarity between the formant transitions of an initial stop, and the formant transitions of the postvocalic unreleased allo-phone of the same stop. Brief two-component stimuli were used to study perceptual similarity among members of a set of synthetic sounds which approximate the mirror-image formant transitions for /b d g/ in prevocalic and postvocalic positions. The two components of a stimulus were 40-msec tone bursts having linear frequency glissandos with frequency motions approximating the first and second or second and third formant patterns. Results indicate that there is no inherent similarity between mirror-image glissando patterns. Judgments of relative perceptual similarity were based on the glissando component corresponding in frequency to the second formant, even when this component was significantly reduced in amplitude relative to the other component. While the perceptual importance of the second formant in speech is well known, it is difficult to account for these results in terms of basic psychophysical data on frequency discrimination, loudness, or masking. These results, and the observation that some mirror-image responses for /g/-like transitions occur under certain special conditions argue for the presence of frequency change detectors that may play an important role in speech perception. [Research supported in part by NIH grants.]
Perceived Stress as the “Standard” for Judging Acoustical Correlates of Stress
Authors: Lea Wayne A.
Published: May 2012

Acoustical correlates of stress can only be evaluated in comparison with some “standard” specifying which syllables are actually stressed. The standard should be consistent from time to time, and largely independent of talker and listener idiosyncrasies. Three phonetically trained subjects listened repeatedly to spoken texts and spontaneous sentences, until they could categorize each syllable as either stressed, unstressed, or reduced. This procedure was repeated three times for each speech text and listener. Two listeners differed from each other on only about 5% of all syllables as to whether they were perceived as stressed or not. Each also showed only about 5% confusions in decisions about stressed syllables from one trial to another. Unstressed and reduced levels were much more frequently confused. The third listener gave less consistent results. Subjects' judgments of stress when given only the written text were of comparable consistency, but did not correspond well with perceptions with speech, if the speech was spontaneous rather than spoken texts. Stress perceptions consequently may be suitable for evaluating acoustical correlates to within a 5% tolerance in overall location scores. Pooling the perceptions from several trials and several listeners may improve the stability of this “standard” for stress assignment.
Prosodic Contours for Auxiliary Phrases
Authors: Allen Jonathan
Published: May 2012

The prosodic contours of the auxiliary phrase of sentences was systematically varied to examine the hypothesis that when the segmental articulation in grammatical units is not made clearly, the information load of these units must be conveyed by syntactic and semantic structure which is partially manifested in the prosodic contour. The syntax of auxiliary phrases is tightly constrained in English, and this syntactic structure is mapped onto the prosodic contour in a preditable way. The prosodic effect of negatives (“He should not have gone”), which appear to be inherently contrastive, is also predictable.
Perception of the Fundamental Frequency of Continuous Speech
Authors: Brandt John F.
Published: May 2012

Three tape recorded samples of sentence material having average fundamental frequencies of 119, 139, and 179 Hz were selected from a larger stimulus set [J. F. Brandt, “Effects of Stimulus Bandwidth on Listener Judgments of Vocal Loudness and Effort,” J. Acousl. Soc. Am. 52, 705–707 (1972)]. The speech samples were presented to five normal-hearing listeners, unfiltered, and high-pass and low-pass filtered at 1500 Hz. Pitch matches to the speech samples were made using a filtered ac pulse train of varying repetition rate and energy centered around 2200 Hz. The fundamental frequency of the speech samples was perceived by the listeners in basically the same way that periodicity pitch (nonspeech signals) information is obtained. That is, the fundamental pitch information contained in continuous speech can be easily obtained from temporal (envelope) information in the physical absence of low-frequency energy. Listeners could also recognize differences between normal-speaking fundamental frequencies and fundamental frequencies produced at frequencies higher and lower than normal.
The Natural Mnemopath—or, What You Know about Words You Forget
Authors: Browman C. P.
Published: May 2012

In the study of recall of words, it has been shown that often certain aspects of a forgotten word are known prior to complete recall of the word, e.g., the number of syllables and the initial grapheme. For the present study, the author collected both the target and approximate words from memory lapses occurring naturally (“mnemopathy”), e.g., one approximation to the desired target word “croquet” was “crochet.” Analysis of the data suggests further factors that are known about forgotten words. In addition to the initial grapheme, graphemes in every position in the target word tend to occur in the approximate word, with greater than chance probability. A final note—more data are needed. The reader is urged to send any instances of mnemopathy, with both the target word and all approximations, to the author.
Phase Fluctuations of Low-Frequency, Long-Range Acoustic Transmissions Received at Mid-Ocean Depths
Authors: Spindel R. C. , Porter R. P. , Jaffee R. J.
Published: May 2012

Time series of phase fluctuations of underwater sound transmissions (406 Hz) between a fixed source and a deep, free drifting hydrophone have been obtained for transmission ranges of 200 km. Phase variations due to hydrophone drift are removed by a bottom-moored CW tracking system that corrects for motions of less than 1% of the transmission wavelength (3.75 m) [“Precision Tracking of Suspended Hydrophone Motion,” J. Acoust. Soc. Am. 54, 276(A) (1973), paper F5]. Fluctuations due to surface reflection are removed by narrow-band filters. Remaining fluctuations are the result of a combination of internal effects including internal gravity waves, random inhomogeneities, and multipath propagation. Results are presented for two types of free drifting hydrophones (sonobuoy deployed and ship suspended) at several depths. Maximum phase fluctuations over continuous four-hour intervals amount to approximately 30 cycles. This compares favorably with sound speed fluctuations recorded along the transmission path. More detailed comparisons of acoustic environmental effects are presented in the following companion paper.
Modulation Distortion in Horn-Loaded and Direct-Radiating Loudspeakers
Authors: Nichols Thomas L.
Published: May 2012

It has been stated that the total modulation distortion produced by a loudspeaker system is inversely related to the efficiency of the system, and that horn-loaded systems display less of this distortion than the best direct radiators [P. W. Klipsch, “Modulation Distortion in Loudspeakers,” J. Audio Eng. Soc. 17, No. 2 (Apr. 1969)]. This statement runs contrary to modulation theory, which relates modulation distortion to the amplitude or velocity of diaphragm vibration. Measurements were made both on a high-quality, full-range horn-loaded system and on a large, full-range direct-radiator system. Each system was driven with the sum of a 41-Hz and a 350-Hz tone to evaluate woofer distortion, and with the sum of a 510-Hz and a 4.4-kHz tone to evaluate mid-range distortion. Output levels ranging up to 110 dB SPL were used. The acoustic output of the speakers was fed to a real-time spectrum analyzer, and total modulation distortion calculated after the method described by Klipsch. Under all conditions measured, the direct radiator produced substantially less distortion. For example, at 110 dB SPL output, its woofer modulation distortion was 3.9% vs 5.8% for the horn system.
A Shipboard Hydrophone Calibrator
Authors: Groves I. D. , Hugus G. D.
Published: May 2012

A hydrophone calibrator has been developed by the Naval Research Laboratory to calibrate hydrophones as large as 12 cm in diameter by the comparison method in the frequency range 25–1000 Hz at sound pressure levels from 130 to 190 dB re 1 µPa. Thus, it is possible to calibrate a hydrophone immediately before deployment and immediately after recovery. The calibration can include the complete electronic measuring system as well as the hydrophone. Vertical stabilization of the calibrator for ship roll and pitch of 10° and isolation from ship's noise are provided.
Noise Ordinances for Michigan Communities
Authors: Wright Wayne M.
Published: May 2012

While the Noise Control Act of 1972 holds the promise that the federal government will eventually provide model codes and other assistance to states and cities, citizen pressures have already led to the enactment of noise regulations in scattered communities. Ordinances have been prepared for a city of moderate size and for two adjacent townships in southwestern Michigan. Essentially, the NIMLO model noise ordinance prohibiting “unnecessary, loud, and unusual noise” has been combined with a section which regulates noise in terms of dBA according to land use zones and type of vehicle (for noise originating in the public right-of-way). The particular circumstances existing in each community, the path followed through the local political system to enactment, and early experiences with enforcement are discussed. Emphasis is placed on compromises that show promise of actually leading to a reduction of local noise levels with the minimal levels of equipment and enforcement personnel that could realistically be expected.
Practical Problems with Implementation of Muncipal Noise Control Regulations and Ordinances
Authors: Salter C. M. , Brittain F. H. , Jones B-J.
Published: May 2012

Until states and municipalities assumed some responsibility for the abatement of noise, courts provided remedies on a case-by-case basis by awarding damages to the private property owner or enjoining the continuance of the noise nuisance. Close to the private nuisance are. the theories of trespass, assault, and “taking” (the exercise of eminent domain by inverse condemnation or easement). Springing from this basic common law action is the remedy of public nuisance municipal ordinances, which take the additional step of striking at the source of noise itself. In this paper we discuss the effectiveness of municipal noise ordinances based on the private nuisance concept, and regulations based on zoning, tax incentives, and outright prohibition. Also related are our opinions of notably favorable and unfavorable enforcement procedures in the San Francisco, Chicago, New York City, Palo Alto, and the League of California Model Municipal Noise Ordinances.
Comparison of Microphone Traverse and Microphone Array for Obtaining Space Average Sound Pressure Level
Authors: Holmer C. I. , Lubman D.
Published: May 2012

The purpose of the microphone system is to provide an estimate of the space average sound pressure level with the minimum possible variance for measurement of a tone. The variance in the estimate for measurement of a tone in a given room is a function of the number of independent samples taken, and the effectiveness of the rotating diffuser at the frequency of interest. Theoretical considerations indicate that the number of independent samples produced by an array is equal to the number of microphones (separated by more than one-half wavelength) which are used. For a microphone traverse, the number of half-wavelengths along the traversing path gives approximately the number of independent samples. Thus, there is always a frequency above which a traverse should provide a lower variance in the estimate than a given array. Experience suggests, however, that the lowest frequency of interest determines the accuracy requirements for the microphone system, assuming a reasonably effective rotating diffuser. In this presentation, it is shown that for “ideal”-shaped rooms with reasonably effective rotating diffusers the difference between the accuracy of the estimate of a large array or traverse is small. However, for rooms with less than “ideal” shape, it is shown that an array can provide substantially improved accuracy in comparison to a traverse due to the increased number of samples which can be generated at low frequencies.