bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Model of the Brass-Player's Embouchure
Authors: Pyle Robert W.
Published: September 2005

A simple mathematical model of the self-oscillating system comprising the oral cavity, the lips, and the input impedance of an idealized brass instrument has been programmed for a digital computer. The lips are represented by a simple mechanical oscillator with amplitude-dependent damping, similar to the model of the vocal cords used by Flanagan and others in speech studies. The input impedance of the “instrument” is that of a horn whose resonances are precisely harmonically related. This formulation gives a set of coupled nonlinear integral-differential equations that can be solved numerically to give approximate values for the pressure in the oral cavity and in the mouthpiece cup, the volume velocity through the lip orifice, and the area of the lip orifice as a function of time. Although it would not be particularly meaningful to compare the computed waveforms in detail with experimental data, this simple model shows many of the characteristics of real brass instruments and should be useful for studying the effects of parameter changes.
Trumpet Intonation Improvement with Multiple Helmholtz Resonator Terminations
Authors: Cardwell W. T.
Published: September 2005

The conventional trumpet mouthpiece has already been shown, theoretically and experimentally, to behave as a Helmholtz resonator termination of the trumpet air column, changing the apparent length of that column with frequency. Further theory indicates that for musically proper placement of the upper playing modes, a more nearly ideal termination would be a multiple Helmholtz resonator. Experiments confirm this.
Oratorios and the Italian Concert Hall
Authors: Shankland R. S.
Published: September 2005

An important factor for concert hall development in Italy are oratorios built adjacent to large churches. Although used primarily for religious services, these often included organ, choral, and instrumental music. The structures were much smaller than churches, which contributed greatly to their excellent acoustics as compared to their parent cathedrals. Other important features include rectangular shape, high ceilings, and placing organ, choir, and altar in a single acoustical air volume. Many oratorios, especially those in Palermo have upper wall surfaces covered with elaborate sculptures. Few music rooms anywhere had such effective sound diffusers. The lower side walls were normally of wood paneling, but when plaster, were covered with Damask. The excellent acoustics of these oratorios provided a stimulating environment for the development of music in Italy. The word oratorio as applied to musical compositions derives from these halls, especially that used by Philip Neri near Chiesa Nuova in Rome. Neri's pioneer compositions stimulated the development of choral and instrumental music throughout Italy, while the architecture of the oratorio played a decisive rôle in the evolution of excellent concert halls in Italy.
Acoustical Design Parameters for Summer Concert Pavilions
Authors: Jaffe Christopher
Published: September 2005

A study and analysis of the acoustical design parameters of the music pavilions at Tanglewood, Meadow Brook, Ravinia, and Saratoga undertaken in conjunction with the development of acoustical design criteria for the Merriweather Post Pavilion of Music at Columbia, Maryland, and the Blossom Music Center in Northampton Township, Ohio. Comparative data on reverberation times, shaping of hall and listening area, acoustic coupling, distribution, and characteristics of lawn area sound were included in the initial survey. Criteria developed for the Merriweather Post Pavilion and Blossom Center is reviewed in relation to the final acoustical report on the completed projects.
Dilatational-Mode Sound Transmission in Sandwich Panels
Authors: Smolenski C. P. , Krokosky E. M. , Ewers G.
Published: September 2005

Dilatational vibration modes in sandwich panels have been shown to produce an undesirable “coincidence-type” response in the sound-transmission spectrum of light-weight sandwich panels in the medium-to-high frequency range. The governing characteristic frequency equations were developed by employing the Rayleigh-Ritz energy principle for a sandwich panel with variable dimensions and properties. The present solution employs a general strain-energy relation without restricting the skin materials to be identical. Eight characteristic natural frequencies involving dilatational, flexural, and longitudinal effects were determined as a function of panel dimensions and material properties for a simply supported panel. Since the dilatational mode is related to the core properties, particular attention was given to the influence of the core properties on the dilatational natural frequencies. A number of experimental scale panels with various skin and core materials were tested under random-incidence sound-transmission conditions and compared with the theoretical predictions.
Plumbing Noise and the Classification of Valve Noise
Authors: Strumpf F. Michael
Published: September 2005

Plumbing noise is a topic often discussed, but despite this fact there still exists a wide range of unknowns related to this particular area of noise control. Research done in Europe and the Scandinavian countries (especially Germany, Denmark, and Sweden) investigated some aspects of the general problem of plumbing noise. As valves are one of the main noise sources in a plumbing system, this subject was investigated first. In addition, valve manufacturers needed some testing method in order to facilitate a redesign of their products with respect to noise. In Germany, work was concentrated on laboratory and field test methods to enable a precise measurement of the plumbing noise. A “noise source” was designed by P. Schneider in Berlin, which enabled relative and absolute measurements. A testing method for the classification of valves developed at the Danish National Institute of Building Research will be discussed in detail. A relative comparison of 13 valves tested under various flow conditions also will be given. In addition, the possibility of classifying a valve by a single number will be discussed.
Significant-Structure Theory of Dynamic Liquid Properties
Authors: Eyring Henry , Jhon Mu Shik
Published: September 2005

An acceptable model of the liquid state should lead to a quantitative theory of thermodynamic and transport properties. For simple substances such as argon, significant structure theory provides such a model without adjustable parameters. For more complicated molecules, a knowledge of certain properties allows one to calculate the remaining properties. A significant structure theory model which suffices to calculate the thermodynamic properties of liquids fixes transport properties aside from the numerical value of the transmission coefficient of reaction rate theory. The present status of the theory and of calculations of the following properties will be discussed: (a) ordinary viscosity, (b) bulk viscosity, (c) diffusion coefficients, (d) thermal conductivity, and (e) dielectric relaxation.
Electronic Excited States of Liquids
Authors: Rice Stuart A.
Published: September 2005

This talk will deal with the study of the electronic excited states of liquids. Our purpose is twofold: (1) to describe these states and understand how electronic excitation may propagate through a disordered system; (2) to understand how molecular motion alters the properties of electronic excited states. It will be shown that, in principle, a study of the electronic excited states of a liquid can lead to useful information concerning the collective translational excitations of the ground electronic state of a liquid.
Hearing in Primitive Mammals
Authors: Masterton Bruce , Ravizza Richard , Heffner Henry
Published: September 2005

As part of a systematic study of the evolution of human hearing, behavioral audiograms have been determined for three varieties of primitive mammals: opossum (Didelphis virginiana), hedgehog (Hemiechinus auritus), and tree shrew (Tupaia glis). Comparison of the three audiograms shows an increase in low-frequency sensitivity that parallels phyletic level while high-frequency sensitivity is nearly constant. The results suggest that low-frequency sensitivity evolved slowly during the early mammalian stages of man's lineage while high-frequency hearing was a commonplace capacity of primitive mammals. [Research supported by N.I.H. grants.]
Vocal Output of Nestling Kittens and Retrieval Behavior in the Cat (Felis domesticus)
Authors: Daly Robert L.
Published: September 2005

Vocalizations of kittens removed from the nest were found to comprise two spectrally distinct classes: (1) highly stereotyped calls with 1–3-kHz peak intensities around 100 dB SPL, and with appreciable energy at 50 kHz. These calls typically consisted of a glissando lasting about 700 msec. (2) Calls with peak intensities around 85 db SPL, which seldom contained energy above 5.8 kHz. These calls varied between and within individuals in both spectral envelope and temporal course. Playback of recorded calls to nesting female cats indicated that females would only investigate calls containing ultrasonic components. The females' behavior appeared further dependent on both repetition rate and tensity of the calls, as well as on nonacoustic factors, such as number of kittens missing from the nest. Spectral modification of the calls was found to affect retrieval behavior. [Work supported in part by the Public Health Service, U. S. Department of Health, Education and Welfare, and by the U. S. Air Force Office of Scientific Research.]
Distribution and Anatomy of Lateral Line Organs in the Tail of the Mudpuppy
Authors: Frishkopf Lawrence S. , Harris Gerard G. , Flock Åke
Published: September 2005

Lateral-line organs, sensitive to water displacement, are found abundantly on the head, trunk, and tail of the larval amphibian, Necturus maculosus. The organs occur along the tail in small linear groups, called stitches, which run rostrocaudally. Each organ consists of a bulb-shaped structure, embedded in the skin and composed of a central group of eight to 10 hair cells surrounded and separated by supporting cells, and of a long narrow cupula extending from the skin surface several hundred microns into the water. Eighty microns long and 20 μ in diameter at the base, with a narrow neck extending to the surface, the hair cell in the mudpuppy lateral-line organs is several times as large as those found in most other animals. Thirty to 40 stereocilia and a single asymmetrically placed kinocilium project from the apical end into the cupular substance. In approximately half the hair cells of each organ, the kinocilium is located toward the caudal side of the cell and in the remainder toward the rostral side. Each stitch is innervated by two large myelinated afferent nerve fibers that branch to all its organs. Knoblike afferent endings, characterized presynaptically by synaptic bodies and surrounding vesicles, terminate at the base of each hair cell.
Receptor Potentials in the Hair Cells of Mudpuppy Lateral Line
Authors: Harris Gerard G. , Frishkopf Lawrence S. , Flock Åke
Published: September 2005

In the tail lateral line of the mudpuppy (see preceding abstract), under Flaxedil immobilization, neural responses evoked from one organ were monitored by a micropipet (KCl) inserted into another organ of the same stitch. Two types of extracellular nerve spikes that locked to opposite phases of a 27-Hz sinusoidal displacement stimulus placed near the cupula were recorded. Under visual observation, a second piper (filled with Niagara Sky Blue 6B, KCl, or KCitrate) penetrated hair cells in the stimulated organ. In addition to a negative de shift, a small (800-μV p-p max) sinusoidal potential of the same frequency as the stimulus was seen occasionally. We believe this is the hair-cell receptor potential because: (1) It occurs only in hair cells as judged by pipet position and by in vivo and histological examination of responding cells that were stained with Niagara Sky Blue dye. (2) It is not a motion artifact since it was reversibly abolished by methylene blue applied to the cupula while the cupular motion and intracellular dc potential remained the same. (3) It occurred in opposite phases in different cells of the same organ with the same stimulation. (4) It was fragile and not necessarily correlated with magnitude and stability of the dc shift. The potential appeared to increase linearly or show saturation with increasing stimulus.
Echolocation: Processing of Range Information by Bats
Authors: Simmons James A.
Published: September 2005

Echolocating bats of the species Eptesicus fuscus and Phyllostomus hastatus were trained to respond to the nearer of two targets in simultaneous discrimination experiments. The acuity of depth or range perception by sonar was measured on a series of range differences from 10 cm down to zero at absolute ranges of 30 and 60 cm. The minimum detectable range difference (75% threshold) was 11 to 13 mm for both species. The shapes of the range threshold curves corresponded roughly to the shapes of the envelopes of the autocorrelation functions of the sonar cries of the bats, even when the envelopes exhibited several maxima. The results suggest that these bats may extract range information from echoes by pulse compression. The matched filter for the sonar receiver may be a correlation network in the bat's auditory nervous system.
Bearing Estimation Using Data from Many Beams
Authors: Shapiro S. D. , Griffith R. J.
Published: September 2005

Let the location of a source of power be given by its polar coordinates. The bearing of the source is the polar angle of its location. Let a set of directional receiving patterns, or beams, be located at the origin of the coordinate system. Each beam is pointed in a different direction. The total power received on each beam is due to the source and noise. Models are presented to describe the dependence of the received powers and their estimates on the source power and bearing. The effect of randomness (noise), such as variation in the medium, is included. Based on these models, we first consider bearing estimation in the absence of randomness but including all sidelobe information. The concept of “virtual source power” is introduced for this purpose. It is then used for bearing estimation when randomness is present giving rise to several nonclassical estimation methods as well as a method using confidence intervals. A variety of squared error techniques are presented, along with comments concerning practical methods of computation.
Detection of Signals in Noise of Uncertain Level
Authors: Spooner Ronald L.
Published: September 2005

It has been found that ocean noise parameters such as the ambient level can vary widely over relatively short periods of time and without any apparent change in sea conditions. In terms of a model for signal detection, these variations can be incorporated as an uncertainty in the parameters of the noise process. This paper considers one aspect of this problem, that of comparing detection performance of various receivers for detecting signals in noise of uncertain level. The receivers considered are the hypothetical Externally Sensed Parameters (ESP) receiver (whose performance serves as an upper bound), the (Bayes) optimum receiver, an estimation receiver, a clipper cross correlator, and two correlation receivers. The performance comparisons indicate that noise-level uncertainty does not seriously affect the upper performance bound and that this bound can be attained for long averaging times by incorporating uncertainty information in receiver design independent of the a priori noise level information. Also, it is found that receivers such as the clipper cross correlator and the standard cross correlator can suffer significant performance loss operating in an uncertain noise-level environment. [Work supported by ONR, Code 468.]
Sequential Classification Model
Authors: Robert Richard A.
Published: September 2005

Sequential classification, or the “sequential M-ary detection problem,” is a decision process in which one wishes to decide between one of n hypothesis and n⩾3. Sequential classification models have received little attention in the literature owing, most likely, to computational problems that arise. The theory is a slight extension of sequential detection theory. Computational aspects of the problem are primarily concerned with the dimensionality of the decision space and the connectedness of the decision space. For a large class of sequential classification problems, one can obtain numerical results economically. Limited computational results for the case of Gaussian observation statistics and n=3 have been obtained, which indicates the structure of the optimum classifier. [This work supported by NSF grant.]
Likelihood-Ratio Detector for a Known Signal in Nonstationary Ocean Noise
Authors: Hatsell C. P. , Nolte L. W.
Published: September 2005

A nonstationary statistical model for ocean noise is presented, utilizing the concept of an n-dimensional vector sample (n samples considered at a time). The standard deviation of the noise is assumed to be Rayleigh distributed. This noise is then used in the design of a likelihood-ratio receiver for the known-signal case. The design philosophy is to realize the likelihood-ratio Λ in the form Λ(ZK = p(Zk|SN,σ)p(σ)dσp(Zk|N,σ)p(σ)dσ, where σ is the standard deviation of the noise and p(σ) is a Rayleigh probability density function. A performance comparison of this likelihood-ratio receiver with a design assuming stationary Gaussian noise (a correlator) shows that the receiver design assuming the nonstationary ocean-noise model is the superior one when both are operated in a shallow-water ocean-noise environment. [Work supported by the National Science Foundation and the Office of Naval Research (Acoustics Programs).]
Theory of Acoustic Spatial Coherence for Long-Range Transmission
Authors: Broek H. W.
Published: September 2005

This model treats the poor acoustic transmission that occurs for long ranges or short wavelengths by replacing the “wavefront” by a number of regions. Phase fluctuations between points within the same region are assumed to be negligible, but phase fluctuations between points in different regions have a uniform distribution between ±π radians. Diffraction from boundaries of the regions contributes appreciably to transmission loss. The transitions between regions are assumed to be discontinuous and moving. The probability (per unit length along a wavefront) of finding such a transition is constant. Therefore, the average array-gain contribution of each pair of receivers declines exponentially with pair separation projected on the wavefront. Increase of range degrades array gain by introduction of additional discontinuities. Delay fluctuations are independent of frequency (over a limited band), and so gain of an array spaced closer than half-wavelength varies as frequency squared. However, for frequencies sufficiently low (infrasound), the period may be greater than possible delay discontinuities and a continuous wavefront may prevail. [Work supported by Office of Naval Research, U. S. Navy.]
Optimum Detection of Signals with Random Wave-fronts
Authors: Seligson C. D.
Published: September 2005

Bryn [J. Acoust. Soc. Amer. 34, 3 (Mar. 1962)] has shown that the optimum detector of a stationary small-amplitude signal by a K element array in the presence of Gaussian noise is quadratic. Under the critical assumption that the signal wavefront is deterministic, he illustrated that the quadratic detector can be realized as a linear network followed by a summer, squarer, and averager. In the ocean, however, a more realistic assumption is that the signal arrives at the hydrophones with relative phases that are samples of a multivariate random process (the “phase process”). In this case, the optimum detector is still found to be quadratic, but it cannot be realized in the form of the Bryn detector. The advantage of the modified detector over the Bryn detector has been calculated when the phase process is Gaussian and the noise is uncorrelated between hydrophones. Then the output signal-to-noise ratios of the two detectors differ by an amount that depends upon the covariance matrix of the phase process. In the extreme case, as the variance of the phase becomes very large, the advantage of the modified detector approaches \ K. [Work supported by the Electronic Systems Command, U. S. Navy.]
Shallow-Water Acoustic Studies
Authors: Sussman Bernard , Kanabis William G.
Published: September 2005

In an attempt to formulate an accurate model for sound propagation in shallow water, several tests were conducted in Long Island Sound. A bottom-mounted projector, located off Block Island, and explosives were used as sources. A bottom-mounted hydrophone off Fishers Island and a hydrophone suspended over the side of a ship stationed near Watch Hill Point served as receivers. The latter hydrophone was used at three different depths. Propagation loss was measured over the two paths and plotted as a function of sea state. The results were compared with current shallow-water prediction equations. Data obtained during the winter agreed fairly well, while data obtained during the spring showed considerably higher loss than predicted. This discrepancy is attributed to the many more bottom bounces than predicted by the shallow-water formulas. A plot of propagation loss as a function of frequency for explosive sources showed a minimum at 140 Hz. Missilyzer analysis of the same data indicated that the lowest normal mode predominates in this channel. This conclusion was borne out by an analysis of propagation loss curves for different receiving depths.
Model Testing of Auditoriums
Authors: Knudsen Vern O.
Published: September 2005

This report first reviews the history of model tests as an aid to the designing of auditoriums, beginning in 1913 with W. C. Sabine's spark photography and eventuating (1934-) with the more sophisticated Spandock three-dimensional models scaled down to 1:10 and 1:5. At UCLA. we use first two-dimensional optical model tests (as developed by R. W. Leonard in 1954), which are expedient for determining approximately optimal shapes in plan and sections, followed, when deemed necessary, by tests of three-dimensional models that range in scale from 1:1 to 1:4 for critical (often repeated) segments of walls and ceiling, and down to 1:24 for the walls, floor, and ceiling, which can be examined separately, and also as progressively assembled into the complete model of the auditorium. Examples will be presented of procedures and findings in connection with the acoustical designing of several multipurpose auditoriums, a theater in the round (240°) with thrust stage, and an experimental shell for symphonic and concert music. Acoustical model testing reveals diffraction effects and echoes (or their absence), and helps in the designing of auditoriums that optimize early reflections, diffusion, reverberation, and sound-level distribution.
Discussion on Criteria Used in Association with Model Techniques, together with Some Practical Examples
Authors: Jordan Vilhelm Lassen
Published: September 2005

In recent years, a considerable number of acoustical criteria (associated with assessment of “the acoustics” of Concert Halls) have been proposed. Almost all of these criteria, one way or the other, are related to the pattern of early reflections, and most of them aim at some numerical definition that again relates to purely statistical concepts such as reverberation time. In applying model techniques, it seems essential to choose a criterion that (1) is easy to measure, (2) is known to have correlation with subjective assessments, and (3) can be shown to give results in models comparable to values measured in full-scale halls. In relation to this approach, some examples of measurements in 1:10 scale models—and, in some instances, also the corresponding finished halls—are cited.
Model Techniques in Architectural Acoustics
Authors: Veneklasen Paul S.
Published: September 2005

Sound sources, microphones, detection, and display are described for the modeling methods for both steady-state and transient types of testing. The methods have been refined for excellent precision for determining diffracted sound levels around complicated building structures and for studying echograms within proposed auditorium designs so as to optimize envelopmental sound. Examples and quantitative results are presented for many types of applications.
Digital Simulation of Sound Transmission in Reverberant Spaces
Authors: Schroeder M. R.
Published: September 2005

Digital computers, through their capability for accurate simulation of complex phenomena, have permitted new insights into a number of important problems arising in sound transmission in reverberant spaces. (1) Starting with reverberation-free speech or music signals as inputs, computers can add echoes and reverberation with specified delays, spectral content, and decay characteristics. The computer produces several output signals that—when radiated from loudspeakers in an anechoic chamber—produce, at a listener's ears, sound-pressure waves resembling those in real halls. To ensure “externalization” and proper directions of echo arrivals, the computer program is based on the measured sound diffraction around the listener's head. This digital simulation method is useful to “pre-audit” architectural designs before construction and to investigate subjective correlates of a wide variety of reverberation processes. (2) Digital computers have made possible the simulation of frequency and space response of stationary sound fields and the calculation of their statistical properties. These properties are important for the design of electroacoustic systems and the evaluation of measurements in reverberant enclosures. (3) Reverberation theories, based on the geometrical acoustics, are being refined by ray-tracing studies on digital computers. These studies have revealed significant discrepancies in existing reverberation-time formulas and unexpectedly large dependencies of the decay rate on the shape of the enclosure and the distribution of sound-absorbing materials.
Neutron-Scattering Investigation of the Dynamics of H2O Molecules in Ionic Solutions
Authors: Safford G. J. , Leung P. S. , Naumann A. W. , Schaffer P. C.
Published: September 2005

Intermolecular frequencies (below 900 cm−1) and diffusive motions of H2O molecules in ionic solutions relative to water were investigated by slow neutron scattering as function of ionic size, charge, and concentrations and of the temperature. For solutions containing small or highly charged ions (e.g., LaCl3, MgCl2, LiCl, and KF), vibrations, which intensify with increasing concentration, appear at similar frequencies to the ion-water librational and stretching frequencies of the corresponding solid hydrates. In contrast, solutions containing large, singly charged ions (e.g., CsCl, KCl) show new frequencies, but these are comparatively broader and weaker. At 1° and 25°C, the diffusive kinetics generally follow a delayed diffusion mechanism. Small or highly charged ions decrease the self-diffusion coefficient and increase the residence time relative to water. The low charge-to-radius ions have the inverse effect. At higher temperatures, the diffusion kinetics depart from the delayed diffusion behavior. [Work supported by the Office of Saline Water, Department of the Interior.]
Raman Spectral Investigations of Water Structure
Authors: Walrafen G. E.
Published: September 2005

Raman spectra from solutions of HDO in H2O and D2O were obtained in the OD and OH stretching regions of HDO with mercury, helium-neon, and argon-ion laser excitation. Compositions ranged from 5–11 mole % D2O in H2, and from 1–12 mole % H2O in D2O; temperatures from 16°–97°C; pressures from 1 to 1360 atm. The OD and OH contours were markedly asymmetric. Pronounced high-frequency shoulders, separated from the contour maxima by inflections, were observed. The shoulders were prominent at high dilution. The intensity of the high-frequency component from the 11 mole % solution increased relative to the low-frequency component with increase of temperature or pressure. Two general classes of interactions involving the OD and OH groups of HDO were indicated (1) a non-hydrogen-bonded class referring to broken or distorted hydrogen bonds, and (2) a hydrogen-bonded class referring to linear (and nearly linear) hydrogen bonds. A ΔH° of about 2.5 kcal/mole O–D⋯O and a ΔV̄ of about −7 cm3/mole O–D⋯O characterize the transformation between classes. A mixture model involving consecutive hydrogen-bond breakage, rather than a continuum model, is in accord with the data.
Phase Variation of the Acoustic Field Along a Ray
Authors: Friedman A. J.
Published: September 2005

We consider the variation of the phase of the acoustic field due to a time-harmonic source located in an ocean having a specially constructed sound-speed profile. The sound speed is assumed to be a function of depth only, and is constant in the lower half-space, continuous at the interface, and increases linearly with distance above the interface. The ray pattern, including caustic and locus of turning points, is found. Expressions for the field are round and evaluated asymptotically. The phase of the field along a typical ray is compared with the phase predicted by classical ray theory. The two expressions for the phase are identical along the entire length of the ray from the source through the turning point to the vicinity of the caustic. The asymptotic theory breaks down in the region of the caustic, but is again valid on the far side of the caustic, where it shows a π/2 radian phase advance over the phase predicted by ray theory. [Work supported by Electronic Systems Command, U. S. Navy.]
Vertical Obstacle Sonar Prototype Trials
Authors: Nickles John C. , Anderson Victor C.
Published: September 2005

Results of trials of the prototype system for the deep submergence rescue vehicle obstacle-avoidance sonar are discussed. Data from the shallow area outside the San Diego Bay, including returns from a sunken ship, and data from deeper water in the La Jolla area, showing features of the terrain, are included. The system operates in a pulsed, active mode, and measures the relative phase of the outputs of two vertically displaced receivers. The arrival angle of back-scattering from the ocean bottom is thus determined. Recorded phase vs slant-range data have been converted by a CDC 3600 computer to elevation vs horizontal range. In the final system, this processing will be done in real time. [This paper represents results of research sponsored by the U. S. Navy's Office of Naval Research and the Deep Submergence Special Projects Office.]
Use of Cochlea Patterns in Speech Analysis
Authors: Mundie J. Ryland , Moore Thomas J.
Published: September 2005

Displays of basilar-membrane displacement generated by employing speech inputs to an electronic model of the inner ear were studied. Included in the sample of speech inputs were nine vowels, each spoken by four speakers (both male and female), and 22 consonants, all spoken by the same speaker. All consonants were uttered as a consonant-vowel pair. Five of the consonants appeared with each of four vowels, four appeared with each of two vowels, and 13 appeared with one vowel. It was found that distinctive features in the generated surfaces could be used to identify the various consonants and vowels employed. With respect to the vowels studied, it was possible to separate and identify the individual speech sounds across speakers. The most important cues for identifying the various speech sounds were found to be those located in the time domain.
Astronaut Maneuvering-Unit Voice Controller
Authors: Herscher M. B. , Kelley T. P. , Clodfelter R. G. , Petroski D. R.
Published: September 2005

An experimental voice controller to be used in conjunction with an astronaut maneuvering unit has been developed by RCA Advanced Technology under the sponsorship of the Air Force Aero Propulsion Laboratory and the Air Force Avionics Laboratory. The voice controller will permit the spaceman to move about freely outside his space capsule merely by speaking commands into his helmet microphone. The experimental unit recognizes 13 command words in continuous speech, in real time, including such combinations as “roll right” and “pitch up.” The command vocabulary was chosen so that no two words differ only by a single phoneme. This was done to ensure that confusion between command words would not occur and so that the equipment could be simplified to the point where it could be built small enough to be included in the backpack of the astronaut. The experimental model is about the size of a suitcase, weighs 25 lb, and consumes 46 W. However, the experimental unit incorporates design principles necessary to construct a space unit that is less than 100 in.3 in volume, weighs less than 5 lb, and consumes less than 10 W.
Exploratory Strategy for the Use of a Dynamic Subword Segment in the Automatic Recognition of Continuous Speech (ARCS)
Authors: Tappert Charles C. , Dixon N. Rex , Beetle David H.
Published: September 2005

The characteristics of continuous speech and present technology make it desirable to segment the speech continuum in such a way as to minimize the number of pattern classes and maximize repeatability of segment extraction and recognition. A transitional segment appears to meet these requirements. The subword segments to be described find support in the growing conviction on the part of researchers that speech is largely a gestural phenomenon; the information-bearing aspects of the acoustic speech signal are therefore dynamic in time. The system utilizes multilevel, hierarchical processing to perform frequency analysis, subword segmentation, pattern recognition, and higher-level linguistic analysis. Preliminary investigations have indicated that this approach is promising as a potential solution to some problems involved in ARCS. [This research was supported by Rome Air Development Center.]
Approach to the Dynamics of Liquids by Far-Infrared Spectroscopy
Authors: Whalley E.
Published: September 2005

Molecular motion in solids is rather well understood in general terms, largely because the potential energy is invariant to translation by a lattice vector. The infrared spectrum of the lattice vibrations in which the molecules can be considered to move as a unit, is rather simple. Out of the 1025 or so normal vibrations, only a handful can absorb radiation, and the infrared spectrum is a series of relatively sharp lines. The far-infrared spectrum of a liquid, on the other hand, is a superposition of the effects of all the molecular motions, some of which are slightly damped and can be considered as resonators and some are so highly damped that they can be considered as relaxors. We are trying to understand the far-infrared spectrum of a liquid by approaching it gradually from the spectrum of a perfect crystal. The first step is to study the spectrum of orientationally disordered crystals, in which the molecules have long-range positional order but no long-range orientational order. There the dynamics, at least of the translational lattice vibrations, are approximately those of a regular crystal, but the electrical properties of the vibrations are not those of a perfect crystal. All the lattice vibrations are now active. The second step is to study the infrared spectrum of a glass. Here all long-range order has disappeared, but the effects of relaxation and diffusion are not very important. The spectrum shows clearly that the vibrations of vitreous silica at about 1012 Hz, are quite different from those of a perfect crystal or of an orientationally disordered crystal. The third step is to study the spectrum of a vitreous phase as temperature is increased. It will be gradually modified as the effects of diffusion and other relaxation effects become important. The paper will review the progress in this program.
Information Contained in Rayleigh and Brillouin Scattering
Authors: Mountain Raymond D.
Published: September 2005

The formalism relating the frequency spectrum of light scattered by density and/or composition fluctuations in a fluid to the material properties is reviewed and the equation of motion approach for calculating the spectrum is described. The type of information that is contained in Rayleigh and Brillouin spectra is described by means of specific examples. A model possessing a large, relaxing shear viscosity is examined and the distribution of relaxation times is related to the spectrum. Two additional models involving order parameters (thermal relaxation and chemical reactions) are discussed. Finally, the prospects for studying liquid-state dynamics by light-scattering techniques are considered.
Cochlear Potentials inside the Cochlear Duct at the Level of the Round Window
Authors: Honrubia Vicente , Ward Paul H.
Published: September 2005

The cochlear microphonics (CM) and summating potentials (SP) produced by sounds ranging in frequency from 32 to 2500 Hz were measured inside the scala media at the level of the round window in guinea pigs, cats, and monkeys. Tuning curves for CM and SP were obtained as a function of frequency. The CM voltage increased at the rate of 13, 20, and 30 dB/decade change in frequency in the guinea pigs, monkeys and cats respectively. The SP was generally positive at low sound-pressure levels and low frequencies and become negative with increase in intensity and/or frequency. In the three species studied, the frequency at which the transition of the SP polarity occured diminished 1 oct for 10 dB increase in the stimulus intensity. [Research supported by the U. S. Public Health Service.]
Correlations between Theoretical and Measured Standing-Wave Patterns in a Cylinder
Authors: Bert Paul A.
Published: September 2005

The solution to the standing-wave patterns in a cylinder closed at one end was approached mathematically as a boundary-value problem. The mathematical solution was verified by means of probing a cyinder every half-inch along the axis while the cylinder was in resonance. The pressure variations from hole to hole were plotted as a function of the distance from the driver. The measured values agreed within 2% of the theoretical values. Measurements were also made of the standing wave when the cylinder was tuned slightly off resonance. A close correlation between predicted and measured values was achieved. As the driving frequency is varied about the resonant frequency, an envelope of pressure values is obtained in the tube that is always equal to or greater in pressure amplitude than the pressure generated by the resonant-frequency standing wave.
Digital Technique for Synthesis of Oboe Tones
Authors: Plitnik George , Strong William J.
Published: September 2005

Luce [PhD thesis, MIT (Feb. 1963)] has shown that the amplitudes of the partials of an oboe tone can be approximately represented by a smooth spectral envelope that is independent of the fundamental frequency. The spectral envelope has two peaks at frequencies of about 1000 and 3000 Hz. For oboe tones played at a dynamic marking of ff, the peaks are of approximately equal amplitude. The second peak is about 3 dB lower than the first peak for mf tones and about 13 dB lower for pp tones. Two digital filters (modeled by the z-transform method), one resonating at 1000 Hz and the other at 3000 Hz, each having an independent amplitude control, were used to approximate the oboe spectral envelope. A common pulse train was used to excite the filters, and the output of the filters was summed. The time-dependent rms amplitude of real oboe tones was plotted with a B&K level recorder and was used to control the amplitudes of the digital filters. Examples of the synthetic oboe tones will be presented.
Quality of Bass Drum Tones
Authors: Fletcher Harvey , Bassett Irvin G.
Published: September 2005

The frequency components of the bass drum tone arise from three sources: (1) characteristic frequencies of the stretched membrane, (2) harmonics generated through nonlinearity of the system, and (3) summation and difference tones from combinations of (1) and (2). With a fundamental of 30 Hz, theory predicts a component at every 3 Hz, although many are too low in intensity to be measured. More than 50 of these have been isolated and studied in this project. The analysis consisted essentially of determining the frequency, maximum intensity level, and decay rate of each component of the tone. Their maximum intensity levels were found to vary from 10 to 40 dB below that of the fundamental, with decay rates from 4.7 to 30 dB/sec. The frequency of the fundamental decreases as the amplitude of the drum membrane decreases, finally becoming constant at low amplitudes. Each of the components has a changing frequency that remains proportional to that of the fundamental. This analysis provides information necessary to produce a computer synthesis of the tone.
Measurement of Acoustical Characteristics of the Concert Guitar
Authors: Kasha Michael , Watson E. Eugene
Published: September 2005

Acoustical intensity output and transient time curves of several different concert guitars (some of new acoustical design) were measured inside a large impedance tube. The tube's diameter was 2 ft and its length was 16 ft in order to accommodate the bodies of the guitars and to measure the low frequency range between 80 and 700 Hz. The strings of the guitars were excited by a mechanical plucker attached to the mounting platform at the end of the tube. Comparisons of the output curves versus frequency for some standard classical concert guitars and some guitars of novel acoustical internal structure are given.
Acoustical Study of Isoparametric Tones in the Female Chest and Middle Registers in Singing
Authors: Large John W.
Published: September 2005

Isoparametric tones (tones of the same fundamental frequency, sound level, and phonemic category in different registers) were studied in order to specify acoustic differences between the female chest and middle registers in singing. Within the same register, marked similarities were found from subject to subject in the distribution of energy among partials. Conversely, marked differences were found between registers. For a given pair of isoparametric tones, the chest register is characterized by greater energy in the higher partials while the middle register has a stronger fundamental. Characteristic of the sonagraphic portrayals of the transition between registers is a frequency perturbation and especially a break in the continuity of the vibrato. These findings would seem to support the theory that it is primarily the waveform of the source (vocal folds) that changes when a change is made from chest to middle register in the female voice in singing. [This investigation was supported in part by the National Institutes of Health under whose auspices the author is a postdoctoral fellow at Stanford University.]
Modern Day Rock-and-Roll Music and Damage-Risk Criteria
Authors: Flugrath James M.
Published: September 2005

Ten rock-and-roll dance bands were recorded in one dance hall catering to teenagers. One hundred measurements each of linear, A scale, C scale, and octave bands 500, 1000, 2000, and 4000 Hz were computed for analysis of variance, average intensity, and standard deviation for the 12-h recording of each dance band. Rock-and-roll music was found to peak at 2000 Hz and C-scale minus A-scale (C − A) values were found to be approximately 1. The standard deviations of scale-weighting measurements and octave-band measurements were found to be quite small, indicating that amplified rock-and-roll music can be considered as a form of “steady-state” sound if many measurements over time are averaged. It was found that the average intensities of several of the dance bands exceeded both “equal-energy” and “average-level” damage-risk criteria.
Dynamic Relations between Speaking and Hearing
Authors: Lane Harlan , Trane Bernard
Published: September 2005

People speak more loudly in a noisy room or when momentarily deafened and more softly in a quiet room or when sidetone is artificially increased. The effort to compensate for these changes in the signal-to-noise ratio, or to match directly changes in the intensity of a model, typically falls about half-way short (in decibel units). This is probably because a speaker considers that he has doubled his vocal level in half as many decibels as it takes for a listener to agree. More concisely, the Lombard-reflex, sidetone-penalty, and equal-sensation functions have slopes with absolute value ∼0.5 because the exponent of the autophonic scale of voice level is twice that of the loudness scale. This amounts to saying that the speaker acts so as to keep the signal-to-noise ratio, and hence his intelligibility, nearly constant; but he is misled by the differing sensory dynamics of speaking and listening. This disparity is important; none of the five functions supports the view that loudness is judged in terms of vocal level (Ladefoged), or the view that vocal level is judged in terms of loudness (Warren).
Voice Classification II: Extension of Sample and Language Independence
Authors: Silbiger Herman R.
Published: September 2005

Additional data have been obtained on the perceptual classification of voices by means of the voice classification by hierarchical clustering method [J. Acoust. Soc. Amer. 40, 1282 (A) (1966)]. The voice sample has been extended to 100 male and 100 female voices. The method appears to yield stable results since the gross structure of the clustering remains invariant. The semantic differential data were also submitted to a multidimensional scaling analysis, parametric mapping, which provided an excellent three-dimensional fit. To investigate any dependence of the classification method on the speaker's language, 20 males whose native language was other than English were recorded in their native language and in English. The clustering analysis showed closely comparable results for the voices speaking either English or the foreign language, with 13 languages represented. This provides additional evidence that the ratings on the semantic differential represent the perception of the voice quality and are not dependent upon extraneous factors.
Simple Technique for Speech Transposition in Real Time
Authors: Flavin Francis E. , Thomas Ian B.
Published: September 2005

If natural speech is filtered so as to remove all formant components except the second formant and then clipped, the resulting signal is highly intelligible. Transposition to lower frequencies is achieved by dividing this clipped signal by two using a simple digital divide-by-2 technique; spectrograms of the resulting signal for speech inputs reveal that the second formant band of the original speech has been transposed down in frequency by 1 oct. A modulator is used to reimpose either the original speech envelope or the envelope of the filtered speech onto the transposed signal. Finally, a low-pass filter having a cutoff of 1250 Hz and an attenuation slope of 48 dB/oct is used to prevent higher-frequency components from reaching the output. Scores on listening tests typically show a sudden increase from near zero to an acceptable figure after listener familiarization with the device output. [Work supported by NASA.]