bluuebunny/crossref_metadata_2025 huggingface dataset:
1800 MHz electromagnetic field effects on melatonin release from isolated pineal glands
Authors: Sukhotina Irina , Streckert Joachim R. , Bitz Andreas K. , Hansen Volkert W. , Lerchl Alexander
Published: November 2005

Abstract:  Isolated pineal glands of Djungarian hamsters (Phodopus sungorus) were continuously perifused by Krebs–Ringer buffer, stimulated with the beta‐adrenergic receptor agonist isoproterenol to induce melatonin synthesis, and exposed for 7 hr to a 1800 MHz continuous wave (CW) or pulsed GSM (Global System for Mobile Communications)‐modulated electromagnetic signal at specific absorption rate (SAR) rates of 8, 80, 800, and 2700 mW/kg. Experiments were performed in a blind fashion. Perifusate samples were collected every hour, and melatonin concentrations were measured by a specific radioimmunoassay. Both types of signal significantly enhanced melatonin release at 800 mW/kg SAR, while at 2700 mW/kg SAR, melatonin levels were elevated in the CW, but suppressed in the GSM‐exposed pineal glands. As a temperature rise of approximately 1.2°C was measured at 2700 mW/kg SAR, effects at this level are thermal. With regard to radiofrequency electromagnetic fields, the data do not support the ‘melatonin hypothesis,’ according to which nonthermal exposure suppresses melatonin synthesis.
Chronic hypoxia modulates the function and expression of melatonin receptors in the rat carotid body
Authors: Tjong Yung‐Wui , Chen Yueping , Liong Emily C. , Tipoe George L. , Fung Man‐Lung
Published: November 2005

Abstract:  Melatonin modulates the carotid chemoreceptor response to chemical stimuli, and chronic hypoxia changes circadian activities and carotid body function. The purpose of this study was to test the hypothesis that chronic hypoxia alters the function and expression of melatonin receptors in the rat carotid body. Effects of melatonin on the carotid responses to hypercapnic acidosis and to hypoxia were determined by spectrofluorometric measurement of cytosolic calcium ([Ca2+]i) in fura‐2‐loaded type‐I (glomus) cells dissociated from carotid bodies obtained from normoxic (Nx) or chronically hypoxic (CH) rats breathing 10% oxygen for 4 wk. In the Nx control, melatonin concentration dependently attenuated the peak [Ca2+]i response to hypercapnic acidosis, whereas it augmented the [Ca2+]i response to cyanide or deoxygenated buffer. Yet, melatonin enhanced the peak [Ca2+]i responses to hypercapnic acidosis or hypoxia in the CH glomus cells. An agonist of melatonin receptors, iodomelatonin also elevated the hypercapnic or hypoxic responses in the CH groups. The melatonin‐induced changes in the [Ca2+]i responses were abolished by pretreatment with nonselective mt1/MT2 antagonist, luzindole, and by MT2 antagonists, 4‐phenyl‐2‐propionamidotetraline or DH97. These findings suggest a functional modulation of melatonin receptors in the glomus cells in chronic hypoxia. To evaluate the level of expression of the melatonin receptors, in situ hybridization study with antisense mt1 and MT2 receptor mRNA oligonucleotide probes was performed on the Nx and CH carotid bodies. There were significant increases in the expression of mt1 and MT2 receptors in the CH comparing with the Nx group. Taken together, our results suggest an upregulation of the carotid expression of melatonin receptors by chronic hypoxia, which modulates the carotid response to melatonin for the circadian influence on breathing.
SHIP2 interaction with the cytoskeletal protein Vinexin
Authors: Paternotte Nathalie , Zhang Jing , Vandenbroere Isabelle , Backers Katrien , Blero Daniel , Kioka Noriyuki , Vanderwinden Jean‐Marie , Pirson Isabelle , Erneux Christophe
Published: November 2005

The src homology 2 (SH2) domain‐containing inositol 5‐phosphatase 2 (SHIP2) catalyses the dephosphorylation of phosphatidylinositol 3,4,5‐trisphosphate [PtdIns(3,4,5)P3] to phosphatidylinositol 3,4‐bisphosphate [PtdIns(3,4)P2]. We report the identification of the cytoskeletal protein Vinexin as a protein interacting with SHIP2. This was achieved by yeast two‐hybrid screening using the C‐terminal region of SHIP2 as bait. Vinexin has previously been identified as a vinculin‐binding protein that plays a key role in cell spreading and cytoskeletal organization. The interaction between SHIP2 and Vinexin was confirmed in lysates of both COS‐7 cells and mouse embryonic fibroblasts (MEF). The C‐terminus was involved in the interaction, as shown by the transfection of a truncated C‐terminus mutant of SHIP2. In addition, we showed the colocalization between Vinexin α and SHIP2 at the periphery of transfected COS‐7 cells. When added in vitro to SHIP2, Vinexin did not affect the PtdIns(3,4,5)P3 5‐phosphatase activity of SHIP2. Enhanced cell adhesion to collagen‐I‐coated dishes was shown upon transfection of either SHIP2 or Vinexin to COS‐7 cells. This effect was no longer observed with either a catalytic mutant or the C‐terminus mutant of SHIP2. It also appears SHIP2 specific; this was not seen with SHIP1. Adhesion to the same matrix was decreased in SHIP2–/– MEF cells compared with MEF+/+ cells. Our data suggest that SHIP2 interaction with Vinexin promotes the localization of SHIP2 at the periphery of the cells leaving its catalytic site intact. The complex formation between Vinexin and SHIP2 may increase cellular adhesion. The data reinforce the concept that SHIP2 is active both as a PtdIns(3,4,5)P3 5‐phosphatase and as a modulator of focal contact formation.
The Vertical Hydraulic Conductivity of an Aquitard at Two Spatial Scales
Authors: Hart David J. , Bradbury Kenneth R. , Feinstein Daniel T.
Published: November 2005

Aquitards protect underlying aquifers from contaminants and limit recharge to those aquifers. Understanding the mechanisms and quantity of ground water flow across aquitards to underlying aquifers is essential for ground water planning and assessment. We present results of laboratory testing for shale hydraulic conductivities, a methodology for determining the vertical hydraulic conductivity (Kv) of aquitards at regional scales and demonstrate the importance of discrete flow pathways across aquitards. A regional shale aquitard in southeastern Wisconsin, the Maquoketa Formation, was studied to define the role that an aquitard plays in a regional ground water flow system. Calibration of a regional ground water flow model for southeastern Wisconsin using both predevelopment steady‐state and transient targets suggested that the regional Kv of the Maquoketa Formation is 1.8 × 10−11 m/s. The core‐scale measurements of the Kv of the Maquoketa Formation range from 1.8 × 10−14 to 4.1 × 10−12 m/s. Flow through some additional pathways in the shale, potential fractures or open boreholes, can explain the apparent increase of the regional‐scale Kv. Based on well logs, erosional windows or high‐conductivity zones seem unlikely pathways. Fractures cutting through the entire thickness of the shale spaced 5 km apart with an aperture of 50 microns could provide enough flow across the aquitard to match that provided by an equivalent bulk Kv of 1.8 × 10−11 m/s. In a similar fashion, only 50 wells of 0.1 m radius open to aquifers above and below the shale and evenly spaced 10 km apart across southeastern Wisconsin can match the model Kv.
Extending Electromagnetic Methods to Map Coastal Pore Water Salinities
Authors: Greenwood Wm. Jason , Kruse Sarah , Swarzenski Peter
Published: November 2005

The feasibility of mapping pore water salinity based on surface electromagnetic (EM) methods over land and shallow marine water is examined in a coastal wetland on Tampa Bay, Florida. Forward models predict that useful information on seabed conductivity can be obtained through <1.5 m of saline water, using floating EM‐31 and EM‐34 instruments from Geonics Ltd. The EM‐31 functioned as predicted when compared against resistivity soundings and pore water samples and proved valuable for profiling in otherwise inaccessible terrain due to its relatively small size. Experiments with the EM‐34 in marine water, however, did not reproduce the theoretical instrument response. The most effective technique for predicting pore water conductivities based on EM data entailed (1) computing formation factors from resistivity surveys and pore water samples at representative sites and (2) combining these formation factors with onshore and offshore EM‐31 readings for broader spatial coverage. This method proved successful for imaging zones of elevated pore water conductivities/salinities associated with mangrove forests, presumably caused by salt water exclusion by mangrove roots. These zones extend 5 to 10 m seaward from mangrove trunks fringing Tampa Bay. Modeling indicates that EM‐31 measurements lack the resolution necessary to image the subtle pore water conductivity variations expected in association with diffuse submarine ground water discharge of fresher water in the marine water of Tampa Bay. The technique has potential for locating high‐contrast zones and other pore water salinity anomalies in areas not accessible to conventional marine‐ or land‐based resistivity arrays and hence may be useful for studies of coastal‐wetland ecosystems.
The mid‐latitude biodiversity ridge in terrestrial cave fauna
Authors: C. Culver David , Deharveng Louis , Bedos Anne , J. Lewis Julian , Madden Molly , R. Reddell James , Sket Boris , Trontelj Peter , White Denis
Published: November 2005

The world's obligate cave‐dwelling fauna holds considerable promise for biogeographic analysis because it represents a large number of independent evolutionary experiments in isolation in caves and adaptation to subterranean life. We focus on seven north temperate regions of at least 2000 km2, utilizing more than 4300 records of obligate cave‐dwelling terrestrial invertebrates. In North America, highest diversity was found in northeast Alabama while in Europe highest diversity was found in Ariège, France, and in southeast Slovenia. Based on these regions as well as more qualitative data from 16 other regions, we hypothesize that a ridge (ca 42°–46° in Europe and 34° in North America) of high biodiversity occurs in temperate areas of high productivity and cave density. This may reflect a strong dependence of cave communities on long term surface productivity (as reflected in actual evapotranspiration), because the subterranean fauna relies almost entirely on resources produced outside caves. This dependence may explain the unique biodiversity pattern of terrestrial cave invertebrates.
Station-Keeping Tests of Moored Caisson in Strong Current
Authors: Chakrabarti Subrata K. , McBride Mark
Published: November 2005

A new suspension bridge is being built over the Tacoma Narrows, Washington. The bridge will be placed on a structure mounted on two large concrete caissons. The caissons are being constructed in a floating position by pouring concrete at site. During this construction period, the floating caissons are moored in place and will be subject to high currents in the Narrows at a range of drafts. In order to investigate the motions of the caisson and the mooring line loads, physical model tests were performed at a scale of 1:100 at HR Wallingford (HRW). The actual bottom contours of the Narrows near the construction site were duplicated in the model. The catenary mooring lines were highly nonlinear. The current forces and moments on the floating caisson included steady and oscillating components due to flow separation and vortex shedding. There is an existing bridge mounted on two piers in the vicinity of the new caissons, which introduced an appreciable flow interference effect. The tests were conducted in both the ebb and flood flow directions so that the effect of the shadowing of the caisson-pier pair could be studied in the tests. The recorded results of the elastic mooring tests were compared in terms of the maximum measured tensions with a time-domain dynamic motion simulation program, MOTSIM. The results of this comparison are presented in this paper.
FPSO-Shuttle Tanker Collision Risk Reduction
Authors: Chen Haibo , Moan Torgeir
Published: November 2005

To reduce the occurrence of tanker drive-off, and to reduce the probability of recovery failure should drive-off happen, are two basic principles to reduce FPSO and DP shuttle tanker collision in tandem offloading. In this paper we focus on measures to reduce recovery failure. Previous analyses revealed that recovery failure probability is high due to a lack of time for the DP operator to initiate the recovery action in a tanker drive-off scenario. To increase the time window and to reduce the operator reaction time are therefore two main principles of recovery failure reduction. A substantial increase of the separation distance between FPSO and the tanker, and a possible reduction of the main propeller(s) forward thrust that can be used by the tanker DP system are two measures to increase the time window. The effective reduction of operator reaction time can be achieved by a number of measures, i.e., selection, training, procedure, crew resource management, and automation support, which are designed to improve early detection as well as effectively reduce the DP operator’s time in diagnosis and situation awareness.
Stereophon Sound Recording System
Authors: Lee H. B.
Published: November 2005

This report describes a system intended primarily for high quality sound recording on film. It was privately developed by a German physicist, Dr. Carlheinz Becker, of Thansay über Rosenheim. The system employs well-known means in some respects, but has the important advantage of giving excellent 3-channel reproduction of great dynamic range and low noise level using a sound track of total width of only 2.65 millimeters.
Some Effects of the Coherence of Ambient Ocean Noise on Passive Acoustic Detection Systems
Authors: Freeman J. J.
Published: November 2005

By postulation of uniform volume distribution of independent noise sources as a model of ambient ocean noise, it is shown that the spatial coherence of ambient noise produces a systematic error in passive detection or direction-finding systems as well as additional fluctuations. Since the coherence between the noise received at two hydrophone locations depends upon their separation, it follows that, for a given receiver separation and hence systematic error, there exists an upper limit for which an increase in the averaging time no longer increases the signal-to-noise ratio, namely, when the fluctuation error becomes equal to the systematic error. Also, the dependence of both signal power and noise power, and hence signal-to-noise ratio, on separation between hydrophones is examined.
Growth of Loudness and Its Relationship to Differential Sensitivity
Authors: Riach Winifred D. , Elliott Donald N.
Published: November 2005

The growth of loudness and its relationship to differential sensitivity for intensity was investigated under normal conditions and under experimental conditions of auditory fatigue. The data used in the determination of the growth of loudness were obtained by the Method of Magnitude Estimation. Differential sensitivity was measured with an amplitude-modulated signal. Three levels of auditory fatigue were utilized; namely, a temporary threshold shift of 10, 20, and 30 db SL. The normal growth of loudness confirms Stevens' findings; that is, ψ=k (θ−θ0)n. The growth of loudness under conditions of auditory fatigue is best described by a higher-order equation. Measures of differential sensitivity do not reflect the same kind of systematic change with an increase in the temporary threshold shift as do the estimates of loudness. The relationship between the growth of loudness and differential sensitivity is discussed.
Acoustic Resonance in Combustion Systems
Authors: McClure F. T.
Published: November 2005

Combustion systems are discussed in terms of their properties as acoustic cavities. Particular attention is paid to those characteristic features that distinguish them from more-conventional acoustic cavities. Special reference is made to solid-fuel rockets as a particular example to illustrate some of the factors in a more quantitative way.
Three-Dimensional Model of the Sound Field Surrounding a Rigid Obstacle
Authors: Harbold Mary L. , Steinberg Bruce N.
Published: November 2005

Extensive study of the sound field in the region surrounding a rigid obstacle has led to the development of a three-dimensional representation of the pressure field. The obstacle under investigation was placed in an anechoic chamber in the path of a plane acoustic wave. The sound field in a selected horizontal plane surrounding the obstacle was studied by automatically moving a small probe microphone through the region at a speed of 4 mm/sec. The signal from the probe microphone was fed to an audiofrequency spectrometer and recorded by means of a graphic level recorder. The data tapes were coordinated to construct a three-dimensional model showing the pressure amplitude as a function of two position coordinates (x and y). Models have been constructed for the sound field in the region surrounding a sphere and a cube at different frequencies. [This work was supported by a Research Grant from Temple University.]
Response of an Elastic Plate Submerged in a Liquid Half-Space to Explosive Sound
Authors: Rosenbaum J. H.
Published: November 2005

An asymptotic solution, valid for long times after the explosion, is derived; it expresses the response in terms of characteristic vibrations of the medium. Special emphasis is placed on the description of sustained reverberations (singing). This phenomenon is described in terms of complex modes [J. H. Rosenbaum, J. Geophys. Res. 65, 1577 (1960)], where some energy travels back radially toward the source; at long times, this leads to standing waves of nonvanishing horizontal wavenumber. Singing is closely connected with trapped waves of high horizontal phase velocity, which are decoupled from the liquid half-space below the plate [M. A. Biot and J. H. Rosenbaum, J. Acoust. Soc Am. 33, 27 (1961)]. At very long times, however, the strongest signal is associated with an almost completely decoupled shear motion of the plate, and the horizontal wavenumber approaches zero. Total transmission curves of plane harmonic sound waves through a submerged plate are used to show qualitatively why singing often may not be observed in connection with the trapped waves mentioned earlier.
Source Level Instead of Sound-Power Level
Authors: Young Robert W.
Published: November 2005

The outputs of sound sources are being reported in a variety of ways, so that it is difficult to grasp quickly their relative significance. For some kinds of noise, computed sound-power levels are frequently given, whereas only sound-pressure levels are ordinarily measured. The whole picture can be clarified by routine use of source level. The (spherical) source level is the sound-pressure level at a reference distance of 1 m (unless otherwise specified) from an equivalent point source. Source level is equal to sound-power level plus an adjustment for the medium and units of measurement. In a free spherical sound field, sound pressure p varies inversely as distance r; thus, source level is 20 log (p×r/p0×r0), where the subscript 0 identifies reference quantities. Hemispherical source level is the sound-pressure level at reference distance from an equivalent hemispherical source. Axial source level is the sound-pressure level produced at reference distance on the axis of maximum response. Duct source level is the sound-pressure level of a free plane wave in a duct of reference cross section that would transmit sound power equal to that emitted by the actual source into the duct.
Noise Generation by Fluid Flow in Ducts
Authors: Ingard Uno
Published: November 2005

On the basis of an analysis of experimental data on flow noise in ducts, the question regarding the existence of a “universal” noise-source spectrum is discussed. [This work was supported in part by the U. S. Army, the U. S. Air Force Office of Scientific Research, and the U. S. Office of Naval Research under Contract Nonr-1841(42).]
High-Temperature Condenser-Microphone System
Authors: Beavers Bob R.
Published: November 2005

A condenser microphone system is described for stable operation at continuous ambient temperatures of 525°F. The system is composed of a 0.300-in.-diam microphone cartridge that mounts on a cathode-follower unit with dimensions of 0.6×1.0×1.8 in. The 0.15-in.-diam diaphragm material lead to a first mechanical resonance at 60 kc/sec. The microphone unit has a sensitivity of −70 dB re 1 V/dyn/cm2. Variations in frequency response are ±1 dB from 20 cps–40 kcps. The sensitivity of theunit is constant within ±2 dB over the temperature range from 0°–525°F. A discussion is presented of the factors that lead to optimum microphone design for use in boundary-layer noise studies. Special materials and components necessary for operation under high ambient temperatures are described.
Absolute Behavioral Auditory Thresholds in Mice
Authors: Warfield Dickens , Ruben R. J.
Published: November 2005

The experiment was designed to obtain behavioral measures of absolute auditory thresholds and to compare them with cochlear potentials and with single-unit eighth-nerve-fiber thresholds. Mice were selected because certain strains display pathological conditions that appear similar to some congenital auditory defects found in humans. The present study deals only with normal mice. Results of avoidance and escape-conditioning techniques are compared, as are results of the psychophysical method of limits and the method of constant stimuli. The animal was trained to avoid shock (in avoidance-conditioning) by responding to the tone alone, or to terminate shock (in escape-conditioning) by making one response to tone plus shock and another to shock alone. The range of frequencies tested was 500–32 000 cps. The test chamber was placed inside a sound-shielded box. Tones were transmitted from one oscillator outside the box. The intensity of all tones and the noise level in the test chamber were measured by a wave analyzer. Shock was administered through the grid floor. Results are discussed in terms of the minimum sound intensity required at the various frequencies, response latency, and response variability. Some problems inherent in the training techniques are described.
Electromyographic Study of the Tongue during Vowel Production
Authors: MacNeilage Peter F. , Sholes George N.
Published: November 2005

Surface electromyograms have been recorded from the tongue during the production of 12 American vowels contained in monosyllabic utterances of the form /pVp/. Electrodes were placed at locations ranging from the root of the tongue, over the mass and blade, to and under the tongue tip. It was found that each vowel shows characteristic patterns of electrical activity over the various locations during its production. Correlations are proposed between these vowel myogram patterns and (1) the musculature controlling tongue movement, particularly the styloglossus and hyoglossus muscles, (2) the acoustically significant place and degree of vocal-tract constriction as shown in cineradiograms of the subjects speaking the same utterances, and (3) traditional phonetic classifications of the vowels. [This investigation was supported in part by PHS Research Grant DE 01774 from the National Institute of Dental Research, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.]
Behavior of the Tongue in the Production of Some Alveolar Consonants
Authors: Harris Katherine S.
Published: November 2005

Surface electromyograms have been recorded for several consonants with a place of articulation in the alveolar region. Discriminable patterns can be identified for /l/, /s/, and /t/, using four locations on and under the tongue tip. A detailed study was made of these patterns in utterance final position, both singly and in cluster with each other and with a nonlingual consonant /p/. Previous results [J. Acoust. Soc. Am. 34, 743 (A) (1962)] had shown that the pattern for the labiodental consonant /f/ is essentialy the same when it is alone in utterance final position, and when it is clustered with alveolar consonants. The present study permits an assessment of contextual effects on alveolar consonants when they are clustered with a nonalveolar and when they are clustered with each other. [This investigation was supported in part by PHS Research Grant DE 01774 from the National Institute of Dental Research, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.]
Automatic Reduction of Vowel Spectra: A Quantitative Analysis of Error Scores
Authors: House A. S. , Paul A. P.
Published: November 2005

Analysis-by-synthesis procedures for automatic reduction of speech spectra describe the goodness of fit between an input-speech spectrum and an internally generated spectrum by an error score. In vowel analysis, the error score typically is derived from a computed-error curve specified by values corresponding to 24 input filters. Values of error scores from a set of utterances by three talkers are presented and compared to similar scores resulting from manual spectrum-matching procedures. Variations in error score attributable to particular vowels, contexts, and talkers are investigated, and the error-score magnitude is related to accuracy in formant location. [This work was supported in part by the U. S. Army, the U. S. Air Force Office of Scientific Research, and the U. S. Office of Naval Research; in part by the U. S. Air Force (Electronic Systems Division) under Contract AF 19(604)-6102; in part by the National Science Foundation (Grant G-16526); and in part by the National Institutes of Health (Grant MH-04737-02).]
Impact-Sound Transmission through Concrete and Wood-Joist Floors
Authors: Huggins Donald N.
Published: November 2005

A wide-spread source of complaints by apartment dwellers is the transmission of impact noises through floors. A program has been conducted to determine the impact-sound-transmission characteristics of concrete and wood-joist floor constructions. The concrete constructions consisted of the 12-in. slab forming the roof of a 10 000-cu-ft reverberation room with test panels of various types and areas up to 16 sq ft laid over the slab. The wood constructions were built into a 10-ft-sq opening in the roof of the reverberation room. Impact-transmission tests were conducted according to ISO/R 140-1960, using the standard tapping machine specified. The criterion used thus far for evaluation of the test results has been the British grade I and II curves that denote relative degrees of apartment-dwellers' satisfaction as determined by extensive field surveys. The grade I curve can be met with a number of practical constructions over a concrete slab, for which data are presented. In wood-joist construction, the grade I requirement is easily met at the higher frequencies, but equivalent low-frequency performance is difficult or impossible to attain because of the inherent lack of mass and rigidity of wood construction in comparison to concrete.
Spectra and Shape of Complex Pulses Reflected from a Slatted Surface
Authors: Courts H. R. , Wittenborn A. F.
Published: November 2005

In order to simulate the acoustic behavior of rooms of arbitrary shape on a digital computer, the scattering of pulses from objects of finite dimensions is under investigation. At the sixty-fourth meeting of the Acoustical Society of America, some audible magnetic-tape recordings were presented of the effect of scattering finite-duration sinusoidal pulses from a slatted surface. In this paper, the spectra and shapes of such pulses are presented. In addition, the modifications in spectrum and shape of a number of noiselike (nonsinusoidal) pulses that are representative of actual stage noises, produced by dancers or by shouting, following reflection from slatted diffracting surfaces, are presented.
Differential Thresholds for Frequency
Authors: Small Arnold M. , Brandt John F.
Published: November 2005

Differential thresholds for frequency at 40 dB SL and at octave intervals from 125 cps to 8 kc/sec, were measured using the method of constant stimulus differences with two procedures. In one case, following the usual practice, both the standard and variable stimuli were presented sequentially in time to the same ear. In the second case, the time sequence was identical but the standard stimulus was presented to one ear and the variable stimulus to the opposite ear. Data previously reported for the situation in which both stimuli are presented to both ears indicate that binaural thresholds are lower than monaural. In contrast to this, the present study shows that an alternate binaural presentation yields significantly higher differential thresholds for frequencies of 250 cps and above. This effect appears to be particularly marked at 8 kc/sec. In addition, the present results support the data of Harris, indicating that monaural differential thresholds at low frequencies are substantially smaller than those reported by Shower and Biddulph. [Supported in part by the National Science Foundation.]
Response of Analyzers of the Bank-of-Filters Type to Signals Generated by Vowel Sounds
Authors: Harris Cyril M. , Waite William M.
Published: November 2005

A number of different kinds of filters have been used, or proposed for use, in speech analyzers of the bank-of-filters type. These include single-tuned, cascaded single-tuned, double-tuned, cascaded double-tuned, Butterworth, Gaussian, and Tchebycheff. Consider a group of such analyzers having identical filter bandwidth and center-frequency characteristics; each analyzer in the group is comprised of filters of a different type. This paper presents a comparison of the analyzers in this group on the basis of errors in location of formants of vowel sounds. In this investigation, the bank-of-filters, as well as the input signals to the analyzers, was synthesized on a digital computer.
Dimensions of Listener Skill in Voice Rating
Authors: Voiers William D.
Published: November 2005

The coefficient of correlation rii, between ratings assigned voices by a single listener and the averages of ratings assigned by a group of listeners was taken as a criterion of the individual listener's skill in rating a given voice characteristic. Values of rii were calculated for 32 listeners on each of 20 rating dimensions (e.g., clear-hazy, loud-soft, heavy-light) that had previously been found adequate to account for the bulk of stimulus (voice) determined variability in listeners ratings of voices. Intercorrelations among the 20 items were calculated following a tanh−1 transformation of the obtained values of rii−. The resulting matrix of interitem coefficients of correlation was subjected to a factor analysis, which yielded five orthogonal “dimensions of voice-rating skill.”
Scout-Vehicle Aerodynamic-Noise Measurements
Authors: Hilton David A.
Published: November 2005

The results of recent free-flight surface-pressure measurements are presented for the NASA Scout launch vehicle for Mach numbers up to about 4, free-stream dynamic pressures up to about 2300 lb/sq ft, and Reynolds numbers based on vehicle length up to about 400 million. Useful data from two onboard microphones up to the time of second-stage firing were telemetered to the ground station for recording and analysis. The over-all surface-noise levels were noted to increase roughly as the dynamic pressure increased, but did not vary markedly as a function of Mach number. However, a Mach-number effect on the spectral content of the surface-noise pressures was noted as a general result of the tests. In particular, the spectra at the higher Mach numbers contained relatively more high-frequency noise and relatively less low-frequency noise than spectra measured at low speeds. The results of the above tests are compared with available data from other free-flight studies.
Acoustical-Attenuation Qualities of Plug Nozzles
Authors: Peter Abe , Kamo Roy
Published: November 2005

A theoretical investigation is presented describing the acoustic-attenuation qualities of plug nozzles over circular nozzles for the case of supersonic flows. The acoustic characteristics of a given nozzle are related to the constant shock-wave structure and, hence, they are a function of the effective shock-wave surface and shape. Thus, knowing the acoustic qualities of a conventional circular nozzle of a given diameter, an estimate of the attenuation properties of a plug nozzle is obtained as a function of the plug diameter and Mach number. Specifically, if C is the plug radius and r is the radius of the conventional nozzle, the attenuation qualities of the plug nozzle as functions of the dimensionless ratio ρ = C/r and Mach number M are obtainable. The final expression is of the form D = log[(1 + ρ2)][1 +k2(1 + ρ−2)]3/2{[1 +k2(1 + ρ2)]3/2−1}[(1 + k2)3/2−1], with D representing the acoustic attenuation in decibels. k is a function of the Mach number and is determined from the properties of the original nozzle.
Need for More Environmental Acoustical Testing
Authors: Overton Jerry B.
Published: November 2005

The need for more acoustical environmental testing is discussed. Various methods of acoustical testing are outlined, including both equipment requirements and procedures. The results of several major acoustical-testing programs at governmental and industrial laboratories are presented. The author concludes that (1) more acoustical facilities are required to establish better procedures and train technicians, and (2) more selective acoustical testing could increase the reliability of aircraft and weapon systems.
Directivity-Factor Computer
Authors: Green Charles E. , Roshon John R.
Published: November 2005

The necessity for an accurate measurement of the directivity factor (DF) or directivity index (DI) of a sonar transducer has become so critically important in the development of high-power projectors that an easy and accurate method of obtaining that figure is imperative. This paper presents an economical electronic computer that will provide a continuous summation of the power distribution in a directivity pattern. A stylus follows the polar plot of a pattern placed on the computer to obtain a direct readout of the pattern factor in one plane. Patterns taken in appropriate planes are averaged to obtain the DF. Information can be inserted into the computer from the calibration equipment instead of a preplotted pattern. With this system, an equipment capability of better than ±0.1 dB is realized.
Sound Absorber for Sonar Test Tanks
Authors: Morris R. E. , Hollister J. W. , Jan B. , Eynck J. J.
Published: November 2005

An underwater-sound absorber has been developed for use in sonar test tanks wherein frequencies of about 2–10 kc/sec are employed. The absorber is in the form of a panel for convenience of installation and removal. It comprises a steel plate, 12-in.-thick, with molded rubber tiles adhered to both faces. The efficiency of the absorber was determined in an impedance tube, and by measurements of reverberation time in a water-filled steel tank.
Evidence for Two Auditory Receptor Organs in the Inner Ear of the Bulffrog
Authors: Frishkopf Lawrence S.
Published: November 2005

Exceedingly sensitive structures for detecting airborne sound are found within the labyrinth of many vertebrates. The inner ear of the amphibian contains two sense organs that have long been regarded as auditory transducers because of their structures and locations, although there has been no supporting physiological evidence. One of these, the basilar papilla, is a phylogenetic precursor of the cochlea. The other, the amphibian papilla, is found only in amphibia. Single-unit recordings from the branches of the eighth nerve of the bullfrog (R. catesbeiana) demonstrate that both the basilar and the amphibian papillae are sensitive to auditory stimuli. Units arising from each organ exhibit sharply frequency-dependent sensitivity (tuning curves), but the frequency of maximum sensitivity (best frequency) for units from each papilla occurs in a different range. Basilar papilla units (termed “simple”) have best frequencies between 1000 and 1500 cps. It is noteworthy that these units cannot be inhibited by acoustic stimuli. Amphibian papilla units (termed “complex”) are more varied in type: among them are auditory units, with best frequencies below 700 cps; traits that respond both to low-frequency auditory and to vibratory stimuli; and units that respond only to vibration. Activity from all of these units can be totally inhibited by sufficiently intense tone bursts of frequency from about 300–1000 cps. It has been shown that this inhibitory interaction is not under efferent control.
Rotational Splitting of Degenerate Acoustic Modes
Authors: Westervelt Peter J.
Published: November 2005

The steady-state response of a rectangular cavity rotating about an axis passing through the center of the floor and ceiling of the cavity is computed under the assumption that one of the walls parallel to the axis of rotation executes sinusoidal pistonlike motion. Losses in the medium and at the walls are included in the analysis. When the floor and ceiling are square, the twofold degeneracy of the lowest two modes of the stationary room is removed by the Coriolis force that couples the two otherwise orthogonal modes. In this case, the splitting is ±8ωR/π2 with ωR being the angular velocity of rotation. The same amount of splitting was found by Lamb in his investigation of tidal oscillations in a rotating rectangular basin [see H. Lamb, Hydrodynamics (Dover Publications, Inc., New York, 1945), p. 330, Eq. 20.] [This work was supported by the U. S. Air Force under contract AF 33(616)-7045 with the Aeronautical Systems Division at Wright-Patterson Air Force Base, Ohio.]
Validity of Thin-Plate Theory in Dynamic Viscoelasticity
Authors: Biot M. A. , Pohle F. V.
Published: November 2005

The exact equations of dynamic viscoelasticity are used to determine the resonance damping for a vibrating plate, which is assumed as isotropic and homogeneous. To determine the validity of thin-plate theory, the same problem is investigated by means of the classical thin-plate equation that does not include shear deformation or rotatory inertia terms. The comparison between the thin-plate theory and the exact theory is carried out for two types of materials that correspond to real and complex values of the bulk modulus. In each case, the shear modulus is μ(1+ig), and values of g to 0.1 were used in the calculations. The two theories are in excellent agreement in a range of wavelengths as low as 10 times the thickness. It is found that thin-plate theory evaluates the damping more accurately than the static rigidity. [This work was performed at the Adelphi Research Center, Garden City, New York, under a contract with the Aeronautical Systems Division of Wright-Patterson Air Force Base, Ohio, AF 33(616)-8274, with M. A. Biot as Scientific Director.]
Role and Limitations of Damping in the Control of Vibration and Noise
Authors: Lyon Richard H.
Published: November 2005

The applications of damping are directed toward the reduction of vibration and noise. In this paper, the limitations and possibilities of achieving useful reductions are discussed. This is done by separating the problem into response and radiation behavior. The prime consideration in the assessment of damping effectiveness is its relative role in affecting the so-called forced and free wavemotions of the structure. The details of the effects depend on pure tone vs random excitation and correlation behavior both in time and space. Thus, in acoustic noise-reduction studies where the forced waves can dominate the behavior, the effect of damping can be quite different from the case of boundary-layer-noise transmission where the free waves dominate the motion. In some cases, it is not sufficient to merely describe the damping by a loss factor. It may be of some significance whether the losses occur at the joints of the structure or occur in a distributed way over the panel. A statistical description of the structure is governed by three parameters: the structural mean free path, the bending wavelength, and the loss factor. The combination of products of these dimensionless factors determines the damping effectiveness. These factors also control certain aspects of the division of radiation damping of the structure. A tabulation of these regimes of behavior is presented. [This research has been supported by the National Aeronautics and Space Administration.]
Acoustic Attenuation and Elastic-Modulus Changes in p-Type Silicon
Authors: Mason Warren P. , Bateman Thomas B.
Published: November 2005

Measurements of the attenuations and velocity changes in p-type silicon have been made for two doping levels. These are for 2.5×1018 and 1.3×1020 boron atoms per cc. The lower doping level shows a large attenuation at low temperatures—8 dB/cm at 480 Mc/sec and 5°K—and a lowering of the elastic-shear modulus of the doped crystal of about 1.7%. The two measurements together give a relaxation time of the form τ = 1.6×10−12eΦ/RT sec; Φ = 0.00075 eV = 17 cal/mole. On the other hand, the highly doped sample has a modulus change of 6% but a very small attenuation. The corresponding relaxation time is τ<10−13 sec independent of the temperature. It appears that these results are consistent with a model that gives, for lightly doped samples, a permanent separation Φ between the light-hole and heavy-hole energy surfaces. This seems to be due to the shearing strain introduced by the small radius of the boron impurity and by the bonding of boron to only three of the nearest-neighbor silicon atoms. When the density of impurities is much higher, the boron appears to segregate out in regions in the order of 0.005 cm diam in which the boron atoms settle in the same relative position in the unit cell with respect to neighboring boron atoms. This results in an unstrained lattice that gives no separation of the light-hole and heavy-hole surfaces. This interpretation is confirmed by the large scattering loss occurring in the most heavily doped silicon, which prevents attenuation measurements above 300 Mc/sec.
Ultrasonic Device for Physiological Mapping
Authors: Carlin Benson
Published: November 2005

Within recent years, the application of pulse-echo ultrasonic devices for mapping the outline of body structures has shown great promise. One such instrument is described herein and contains a number of features that are original and that are specifically designed to make it adaptable for medical use. Among these are six types of readout, including A, B, C, counter, and two tape-writing types, enabling information to be presented in many novel forms. Among the applications that are now close to clinical use are measurement of brain centerline shift and other brain structural details, and indication of mitral-valve deficiency. Among those medical applications that are still experimental, but that show great promise, are measurement and location of arteries, location and mapping of the unborn fetus in humans, measurement and continuous monitoring of the development of the ovum in various birds, location and mapping of muscular and bone structure both at rest and in motion, investigation of dental structure, measurement of fat layer, etc. The ultrasonic pulse-echo technique has great advantages in that it is completely without danger at the powers used, it can be applied without any discomfort, and without operating on the patient, it is instantaneous, and yet can be easily adapted to permanent records, and in general the apparatus is neither expensive nor difficult to construct.
Note on Internal Conical Refraction of Transverse Mechanical Waves in Quartz
Authors: McSkimin H. J.
Published: November 2005

An analysis is made to clarify the subject of “internal conical refraction,” a phenomenon relating to the direction of maximum energy flow for plane transverse waves in certain crystalographic directions of crystals. It is shown that superposition of the two basic transverse waves involved correctly predicts this direction in regions where both waves coexist. When a small directive transducer is used, spatial separation of the two generated waves may occur; and for this case conical refraction, of course, does not apply. Experimental results for propagation in the Z direction of quartz are described.
Sonic-Induced Vibration and Control for Advanced Spacecraft
Authors: Lee S. Y.
Published: November 2005

Advanced spacecraft and space stations are designed to remain in space for a prolonged period of time. In some cases, the structure of these vehicles can be excited by modulation of the internally pressurized media and externally exposed to space vacuum. In other cases, the structure is immersed in vacuum and excited externally by the impingement of the control jets. In either case, atmospheric damping is absent from the side of the structure exposed to vacuum. This problem is investigated theoretically and experimentally in terms of three types of specimen structural panels: aluminum, viscoelastic, and honeycomb. With one side of the panels in near vacuum, sonic excitation was applied to the other side. This excitation consisted of (1) constant-amplitude sinusoid, (2) random-amplitude sinusoid, (3) constant amplitude but random frequency, and (4) random amplitude and frequency. These forcing functions simulate the sonic excitation induced by various sources, such as equipment noise, multiple spacecraft dockings, micrometeor shower, space-station repair work, control jets, etc. The methods considered for controlling these sonic-induced vibrations include the altering of resonances response due to mass coupling, and the attenuation of response due to viscoelastic and aquaplus damping. The relative damping efficiency of treatments embracing different areas of the aquaplus coating was also investigated. The effects of hysteresis and air-damping on a panel of arbitrary curvature can be expressed in a generalized mathematical equation.
Correlation of 630-cps Shallow-Water Ambient Noise with Wind Speed and Wave Height under Transient Conditions
Authors: Penhallow W. S. , Dietz F. T.
Published: November 2005

In order to determine the correlation of shallow-water ambient noise with wind speed and wave height under transient conditions, 744 observations of sound-pressure spectrum level, wave heights, and wind speed were made in the West Passage of Narragansett Bay during January 1962. Signals from a barium titanate hydrophone located 1000 ft offshore in 40 ft of water were filtered by a B&K 13-octave filter centered at 630 cps. A parallel step-resistance wavegauge and a Bendix-Friez anemometer were used for wave-height and wind-speed determinations, respectively. The data were divided into 39 different groups: 13 groups when the wind was building up, 14 groups under steady-state conditions, and 12 groups when the wind and waves were decaying. Measurements were made at approximately 14-min intervals. Simple and multiple correlation coefficients were determined. The results are discussed in terms of the latest theories of surface-noise generation. [This work was supported by the U. S. Office of Naval Research under contract.]
Underwater Surface-Wave Propagation and Radiation
Authors: Feder Michael P. , Middleton Foster H.
Published: November 2005

An investigation was conducted to observe underwater surface waves traveling on the boundary between an elastic solid and a liquid. The study was carried out for the purpose of determining the acoustic-radiation pattern in the liquid produced by a surface wave at a boundary discontinuity (such as, end of bar). After a brief discussion of the mathematics of surface waves and a description of the experimental apparatus, the results of the investigation are presented. The description of the apparatus includes a detailed picture of the variable-angle wedge transducer that was used to generate the surface waves. The experiment was conducted using rectangular aluminum bars as the elastic solid and fresh water as the fluid. The results show that a surface wave can easily be propagated along a boundary between an elastic solid and a fluid. Also, a high directivity is associated with the acoustic energy radiated into the liquid by the surface waves as they encounter the boundary discontinuity.