bluuebunny/crossref_metadata_2025 huggingface dataset:
Second-Order Auditory Pathways to the Superior Olivary Complex in the Rhesus Monkey
Authors: Strominger N. L.
Published: October 2005

Unilateral stereotactic lesions were made in the cochlear nuclei as follows: restricted to the caudal pole of the dorsal cochlear nucleus (Dc) (N = 2); restricted to the posterior end of Dc (N = 2); involving Dc and the posteroventral nucleus (Pv) (N = 2); confined to the anteroventral nucleus (Av) (N = 4); involving Av and Pv (N = 1); and involving Av together with Dc (N = 3). Monkeys were sacrificed after 6–17 days. Material was stained by the Nauta-Gygax (1954) technique and as described by Fink and Heimer (1967). Data indicate that fibers from Dc, Pv, and Av enter the dorsal acoustic stria, intermediate stria, and trapezoid body, respectively. Regarding the superior olivary complex, Dc projects only to the contralateral lateral superior olive (SOL) and fibers are scant; Pv projects bilaterally to the SOL, preolivary nuclei (PON), and dorsal retro-olivary group, and to the contralateral medial trapezoid nucleus (MTN); and Av projects bilaterally to the PON and medial superior olive (SOM), to the ipsilateral SOL, and to the contralateral MTN. Av efferents terminate on laterally oriented processes of ipsilateral SOM and medial processes of contralateral SOM, and are topographically organized in the vertical dimension. [Supported by NIH grants.
Design for a Parametric Study of Neurons in the Inferior Colliculus Using Stimuli of Varying Informational Value
Authors: Barrett T. W.
Published: October 2005

Using elementary signals defined Δf⋅Δt = 12 and f0⋅t0 = 12 (Δf = bandwidth, Δt = duration, f0 = center frequency, t0 = center period), dichotic stimuli were delivered at cats' ears and varied interaurally by differences in intensity (Δi), time of signal arrival (Δτ), and both Δi and Δτ in an attempt to at least approximate a parametric study of neurons in the inferior colliculus in the time available for recording. Changes of Δτ and Δi with either right or left ear leading in some units had noticeable effects on the profile of post-stimulus time (PST) histograms with increased effects at some delays than at others. The registration of Δτ and Δi is either by a PST histogram profile or by a change in maximum spike count. Changes in the f0 of the Δf⋅Δt signal and of Δt influenced the PST profile indicating not merely a Δi⋅Δτ trade but a Δf⋅Δt⋅Δi⋅Δτ = a constant function. For some units of the inferior colliculus, therefore, a constant response is elicited by a constant product of four stimulus parameters that may change inversely.
Acoustics in the Design of Synagogues in Israel
Authors: Strumpf F. Michael , Shafrir Zvi
Published: October 2005

Jewish Temples, often called Synagogues, are more than just praying centers. They also form a cultural center. The praying auditorium requires a unique acoustical treatment. This praying auditorium differs from other auditoriums (churches or theaters), in that the audience is an active participant. As such, the auditorium requires a special acoustical design, which considers three important functional regions. The first region is the rear and balcony, which requires a highly absorptive environment. The second is the rest of the audience volume, which requires optimum low reverberant conditions. The third is the front stage, which should reflect acoustically to all other sections. Cultural activities in the adjacent environment have to be considered in the auditorium design as an additional parameter. We will present an example of a design that has used all the above parameters in order to improve the acoustics in a Synagogue.
Influence of Microstructure on Oblique-Incidence Behavior of Fibrous Absorbents
Authors: Attenborough K.
Published: October 2005

A scattering approach, which essentially treats a fibrous absorbent as a suspension of parallel fibers in air, suggests that such absorbents are externally reacting. Furthermore the analysis indicates that the oblique-incidence behavior is greatly influenced by microstructure. Theoretical curves are presented for incidence in planes parallel and normal to the axes of the fibers. These correspond to an anisotropic and an isotropic case, respectively. The influence of random orientation and distributions of fiber radii are also considered.
An Investigation Into the Transmission of Sound Between Rooms with Interconnecting Services Using Statistical Energy Analysis
Authors: Mackenzie R. K. , Lyon R. H.
Published: October 2005

The theoretical treatment for sound transmission into and out of a duct of infinite and semiinfinite length is given for single and multimodal panel resonance conditions. This theory is then applied to specific cases and compared with the results from experimental measurements in the laboratory in which the effect, upon sound transmission loss, of varying sectional area and shape, duct wall thickness and internal lining is shown. [Work sponsored by National Science Foundation.]
The Influence of Air Flow Resistance upon the Sound Transmission Loss of Lightweight Concrete Walls
Authors: Mackenzie Robin K.
Published: October 2005

A brief account is given of the effect of air flow resistance, porosity, and tortuosity upon the permeability of rigid materials. The relative effects of paint and plaster finishes upon the acoustic impedance of lightweight concrete block walls manufactured from expanded slate and clay aggregates are described, and an indication is given of the most suitable form of wall construction to achieve maximum sound insulation. [Work supported by Cement and Concrete Association.]
A Study of the Effect upon Sound Transmission of Absorption within the Cavity of a Timber Stud/Plasterboard Partition
Authors: Mackenzie Robin K.
Published: October 2005

A study has been carried out to measure the effect upon sound transmission loss of placing various forms of absorptive material in the cavity of a timber stud partition. Results shall be presented relating to measurements where the density, rigidity, thickness, area covered, and position of the absorptive material was varied. These results are compared with theoretical curves and conclusions drawn for the optimum use of absorptive material from the point of view of effectiveness. [Work supported by the Cruden Foundation.]
The Problem of Acoustical Specifications for Office Landscape Ceilings
Authors: Hamme R. N. , Huggins D. N.
Published: October 2005

Laboratory mockup measurements of interzone attenuation and subjective judgments of speech privacy can be coordinated through the structure of speech-intelligibility theory to evolve a method of ceiling characterization that offers a sensitive scale for performance evaluation with respect to office landscaping. When the results of such characterizations are interpreted in terms of specular reflection losses incurred during interzone transmission, the sufficient conditions for adequate interzone speech privacy beneath flat ceilings can be stated concisely in terms of material properties and the characteristics of a synthetic background-noise distribution system. Certain of the practical ramifications and logical extensions of this treatment of landscape acoustics are also discussed.
Acoustical Performance of Landscaped Office Ceilings
Authors: Sabine Hale J.
Published: October 2005

Data is presented on a number of ceiling materials and assemblies tested in the open office mockup at the Geiger and Hamme Acoustical Laboratories. The tests include flat ceilings, baffle configurations, three-dimensional ceilings, and lighting troffers. Performance is rated in terms of speech attenuation over a 5-ft high screen, and by subjective listening tests. Relations between attenuation, specular reflection loss, and reverberation room absorption coefficients for flat ceiling materials are discussed.
Electret Transducers: A Review
Authors: Sessler G. M. , West J. E.
Published: October 2005

Condenser transducers made with thick wax electrets were first suggested more than 40 years ago by Nishikawa and Nukiyama [Proc. Imp. Acad. (Tokyo) 4, 290 (1928)]. Electret transducers are now in wide use after the introduction of foil electrets (charged polymer films about 1 mil thick) with long charge lifetimes [G. M. Sessler and J. E. West, J. Acoust. Soc. Amer. 34, 1787 (1962); 40, 1433 (1966)]. The charge of the electret replaces the dc bias required in conventional condenser transducers. Charging of the foil is possible with a variety of methods based on thermal, corona-discharge, or electron-beam techniques. Charge retention is particularly good on halocarbons (Teflon FEP, Teflon TFE, Aclar, etc.), where characteristic decay times under normal environmental conditions are measured in terms of decades. Electret transducers have been built as microphones with nondirectional and directional characteristics, as microphone arrays, as earphones, and as electromechanical transducers. Especially electret microphones found widespread practical applications during the past years. Their advantages are excellent frequency response, low distortion, small vibration sensitivity, ruggedness, and low cost.
Optimization of a Ridge Backplate for Electret Microphones
Authors: Madsen H. S.
Published: October 2005

The desired properties for most microphones are high sensitivity, flat frequency response, insensitivity of response to vibration and temperature fluctuations, and long life. The life of an electret is particularly important since the self polarization has a natural decay. It is possible, however, to design an electret microphone that has little variation in sensitivity even though the charge density of the trapped charges diminishes to 14 of its original value. This is possible by controlling every contributing parameter. The parameter that is hardest to control is the tension of the polymer diaphragm and the problem has been resolved by choosing a rectangular backplate with a diaphragm tensioned across parallel ridges. Stray capacitance and electrical load are among the parameters that affect the stability of the microphone, especially when the microphone becomes small as for a lightweight operator's headset. The results of computations and experiments are given.
Parametric Transmitting Arrays: A Review and Some New Developments
Authors: Berktay H. O.
Published: October 2005

Since Westervelt [J. Acoust. Soc. Amer. 32, 934–935(A) (1960); also 35, 535–537 (1963)] put forward the concept of parametric acoustic arrays, a great deal of effort has gone into extending his model of a line array with exponential taper to cover primary field distributions that can be realized in practice. Some of these models and their significances will be reviewed and the results of some new work in this field will be presented, with particular reference to the effects in the nearfield of parametric arrays. [Part of the work to be reported is being supported by the Office of Naval Research.]
Nonlinear Attenuation and the Parametric Array
Authors: Bartram James F. , Westervelt Peter J.
Published: October 2005

The average intensity of a finite-amplitude wave satisfies a simply expressed energy conservation law [P. J. Westervelt, in L. Cremer, Ed., Proc. Int. Cong. Acoust., 3rd (Elsevier, Amsterdam, 1960), p. 316] in terms of the coefficient of small-amplitude attenuation, the first-order pressure, and the virtual source density. This equation when applied to a plane wave yields an equation for the attenuation of the pressure amplitude, in terms not only of the small amplitude attenuation coefficient, but also the shock formation distance. This latter equation exhibits a smooth transition through the region of shock formation. An approximation applicable to the end-fire array can be developed, and from this a compatible end-fire virtual source distribution. This source distribution results in a directional pattern modified from the low-amplitude Rutherford law [P. J. Westervelt, J. Acoust. Soc. Amer. 35, 535 (1963)] by a multiplicative factor, which is expressible as a hypergeometric series. This series can be summed exactly on axis, and a simple closed-form expression giving the reduction in sound pressure level due to saturation is found. These results, obtained independently by each of us, are to be published, flint in a Letter to the Editor by J. F. B. accepted by J. Acoust. Soc. Amer. and later in greater detail in a joint paper by both of us.
High-intensity Effects in the Parametric Transmitting Array
Authors: Merklinger H. M.
Published: October 2005

A method is described wherein the endfire array treatments of Westervelt [P. J. Westervelt, J. Acoust. Soc. Amer. 35, 535–537 (1963)] and Berktay [J. Sound Vibration 2, 439–461 (1965)] may be modified to include the effects of a high-intensity primary wave. An approximate empirical expression for the total acoustic intensity of a finite-amplitude plane wave is employed to determine the source function along the array. It is shown that in the limit of a very intense primary wave, the scattered sound waveform in the forward direction does not depend upon the parameter of nonlinearity The beam pattern (calculated for the case of periodic on/off modulation of the primary wave, only) is shown to narrow as the parameter of nonlinearity is reduced. Various effects related to harmonics of the “difference” frequency are discussed briefly. [This work was carried out at the University of Birmingham under the sponsorship of the Admiralty Underwater Weapons Establishment, Ministry of Defence (Navy).]
On the Conversion Efficiency of a Parametric Source
Authors: Fenlon Francis Hugh
Published: October 2005

Plane and spherical wave solutions of the coupled modal form of Burgers' equation, derived by the method of successive approximations, are treated as two asymptotic limits to define the conversion efficiency of a parametric source operating below the shock threshold. These solutions are then related to the dual frequency form of the Bessel-Fubini series, modified approximately to include the influence of viscous absorption over a specifiable range. Examples of parametric source levels computed by means of these relationships are compared with experimental data published in the literature, and the utility of the solutions for predicting the form of the difference-frequency signal as a function of range is also established. Finally, the theoretical expressions that have been derived are summarized in the form of an extremely simple criterion for calculating equivalent parametric source levels, which can readily be extended to sources operating above the shock threshold by means of an approximate finite-amplitude absorption coefficient.
Potential Use of Parametric Sonar in Marine Archeology
Authors: Muir T. G. , Adair R. S.
Published: October 2005

Over the past few years, the location and recovery of artifacts buried in marine sediments has been enhanced by the utilization of several technological innovations. Acoustical technology appears to offer a potential application in the high-resolution delineation of archeological sites. Good acoustic penetration of marine sediments, however, usually requires a low-frequency sonar, and this requirement is not compatible with the realization of good angular resolution, at least for systems of reasonable size. Parametric arrays with their low-frequency, high-resolution capability, appear to be well suited to these conflicting requirements. The results of several measurements made with one such array are presented in support of this contention. These results include acoustic propagation and beam pattern data obtained in sea water on a 20-kHz difference frequency radiation generated by the nonlinear interaction of 190- and 210-kHz carriers that were transmitted from a 17-in.-diam line-in-cone source. It is also shown that a 5-in. diam aluminum sphere, buried to a depth of 6 in. in a fine sand sediment, was detected with the difference-frequency radiation but not with the carriers. [This work sponsored by the Office of Naval Research.]
Experimental Sonar Equipment using a Nonlinear Projector
Authors: Pearce G. , Berktay H. O.
Published: October 2005

A sonar equipment consisting of an experimental nonlinear transmitting array and associated electronics together with a conventional commerical sonar receiving and recording system operating at a carrier frequency of 45 kHz was assembled. Acoustic measurements were made on the transmitting array at its primary frequencies of 465 and 510 kHz, and at its secondary frequency. Echoes from various targets were recorded when the apparatus was used for horizontal searching. Comparison was made with a conventional system by replacing the parametric transmitter array by an ordinary commercial sonar projector and examining the recorded echoes from the same targets.
Simulated Vocal Cord Motions in Speech and Singing
Authors: Titze Ingo R. , Strong William J.
Published: October 2005

Vocalis muscle and vocal ligament are modeled separately, each by a row of eight masses, with 2 degrees of freedom per mass. This allows for motions in the direction of the flow and transverse to the flow. Vertical phasing at low pitches and horizontal phasing at high pitches are demonstrated. Parameters, which can be adjusted at liberty, are cord elasticity, ligament tension, vocalis tension during contraction, subglottal pressure, and the cord boundary. The variable boundary is employed to allow for various statically strained conditions, such as medial compression and open chink. The normal modes of the system are seen by applying either a sudden burst of pressure (such as in a cough) or by displacing one or several of the masses and allowing the motion to come to rest. Chest, middle, and high registers are demonstrated, including a register transition.
New Paint-On Electrodes for Surface Electromyography
Authors: Allen G. D. , Lubker J. F. , Harrison E.
Published: October 2005

A NASA-developed paint-on electrode has been adapted for biomedical applications by the Research Triangle Institute. 10 g of silver flake are suspended in 10 g of Duco cement and 1 oz of acetone. This mixture may be stored indefinitely, with occasional addition of acetone for thinning. In electromyographic use, each electrode is formed by placing a small (or large) drop of mixture on the skin, letting the acetone evaporate, laying the bare end of the lead-off wire over the resulting silver spot, placing another drop of mixture over the wire, and letting the resulting “silver sandwich” dry. This process typically takes less than a minute, and the electrode will remain firmly in place for hours. This paper will discuss the properties of electromyographic signals gathered by means of these paint-on electrodes, as compared with those from hooked-wire electrodes inserted in the same muscles, and will mention the potential usefulness of these electrodes for investigating the development of speech and other motor control patterns in children.
Frequency Control of Single Motor Units in Upper Articulatory Musculature
Authors: MacNeilage P. F. , Szabo R. K.
Published: October 2005

Frequencies of firing of single motor units were investigated primarily in four muscles; genioglossus, geniohyoid, mylohyoid, and anterior belly of the digastric during isometric and isotonic contractions. Isometric contraction was studied as subjects maintained units at regular firing rates by use of feedback provided by auditory and visual displays of the units (motor unit training). Representative results from relatively small samples obtained so far are as follows. Modal firing rates of individual units ranged from about 10 to 40 impulses per second in different units, with most rates between 20 and 30 ips. The latter values can be compared with values of 10–14 ips from brachial biceps. The frequency range within which regular firing can occur appears to be larger in these units than, for example, in biceps. Differences in typical firing rates from muscle to muscle will be considered. Isotonic contraction in speech gestures was accompanied in some units by firing rates of up to eight times their modal isometric value. [This work was supported by grants from the National Science Foundation.]
Intraoral Air Pressures Associated with Stop Consonants in Various Phonetic Environments
Authors: Ruder Kenneth F. , Brown W. S.
Published: October 2005

Previous research has demonstrated that intraoral air pressures associated with stop consonants vary as a function of the contextual environment of the consonant (initial, medial, or final syllable position). In the present study, the effect of adjacent phonemes on the intraoral air pressures for the stop consonants /p/, /b/, /t/, and /d/ was investigated. Recordings of peak intraoral air pressures were obtained from five subjects for each of the four stop consonants in the environment of high front vowels, low front vowels, high back vowels, low back vowels, and other consonants. Highest intraoral air pressures were associated with the stop consonants in the consonant environment; the next highest pressures were associated with the high vowel environment while the lowest pressures occurred in the low vowel environment. No differences in intraoral pressures for the four stop consonants were observed in comparison of the front and back vowel environments. These findings can be interpretd as reflecting a coarticulation effect and thereby demonstrate that phonetic environment does affect the magnitude of the intraoral air pressures associated with stop consonants. The data from the present study also support the trend reported in previous studies for higher intraoral pressures to be associated with voiceless consonants.
Temporal Characteristics of Velopharyngeal Muscle Function
Authors: Lubker J. , Lindqvist J. , Fritzell B.
Published: October 2005

Temporal characteristics of palatoglossus and palatal levator muscle action in nasal consonant production were studied in seven Swedish speakers. Single motor unit potentials from these muscles were detected by inserted wire electrodes, stored on magnetic tape, and later recorded on light-sensitive paper for analysis. Results suggest that (1) the palatoglossus contracts to lower the palate actively for nasal consonant production; (2) there is a simultaneous relaxation of the palatal levator; (3) the EMG data show considerable temporal variability in the face of quite invariant acoustic data; and (4) in spite of the temporal variability, there is enough consistency to allow the development of a simple model of palatal coarticulation. Specifically, we suggest that for the production of nasals the palatal musculature functions rather grossly. The levator relaxes its activity in a gatelike fashion, allowing a temporal space during which the palate is easily lowered. During the open phase of the gate a slight pull is provided by the paltoglossus to assist in palatal lowering. During this “gating” and “pulling” process the articulators function for the actual production of the nasal. The position of the “gate” and its concomittant “pull” vary temporally with respect to the acoustic signal of the nasal in a highly predictable manner, largely dependent upon intraoral pressure requirements of adjacent phonemes.
Ultrasonic Study of Vocal-Fold Vibration in Normal and Nasalized Vowels
Authors: Hamlet S. L.
Published: October 2005

Nasal coupling reduces the over-all intensity of a vowel, requiring greater vocal effort to match intensity of a nonnasal vowel. The question is to what extent increased vocal effort for nasal vowels is reflected by a change in duty cycle of vocal-fold vibration. Duration of the vibratory open phase was taken as the time within each cycle during which ultrasonic transmission through the larynx was blocked by reflection from the glottal rim. This measurement is consistent over the small range of transducer positions permitting the ultrasonic beam to pass through the approximate vertical and horizontal midpoint of the vocal folds. At matched microphone signal smplitudes, duty cycles differ for normal and nasalized sustained vowels, spoken at the same vocal fundamental frequency. Results are reported for preadolescent boys. [This investigation was supported by a NIH Grant.]
Natural Frequencies of Clamped, Generally Orthotropic Rectangular Plates
Authors: Laura P. A. , Maurizi M. J.
Published: October 2005

This study deals with the determination of frequencies of vibration of clamped rectangular plates using a simple polynomial approximation. The plates are considered to be constructed from an orthotropic material such that the principal elastic axes of the materials are not parallel to the plate edges. A weighted-residual technique is used to solve the differential system, and the change in fundamental frequency is investigated as the material elastic axes are rotated with respect to the natural coordinate system of the plate.
Fundamental Frequencies of Noncircular Elastic Hinged Arcs
Authors: Romanelli E. , Laura P. A.
Published: October 2005

Free vibrations of elastic, hinged, noncircular arcs have been investigated by several authors. In general, the spatial derivative of the radius of curvature has been neglected. The present study deals with the determination of the fundamental frequencies of several noncircular arcs vibrating in their plane taking into account the variation of the initial radius of curvature with respect to the spatial variables. Several interesting conclusions are obtained.
Damped Lateral Vibration in Axially Creeping Beam with Random Material Parameters
Authors: Huang W. N. , Cozzarelli F. A.
Published: October 2005

It is assumed that the material of the beam is governed by a nonlinear Maxwell model. The temperature and imperfection density and consequently the two inelastic material parameters are taken as random functions of the distance along the neutral axis. A perturbation about the initial axial stress is employed, analogous to the approach used in Cozzarelli, Wu, and Tang [“Lateral Vibration of a Nonlinear Viscoelastic Beam under Initial Axial-Tension,” J. Sound Vibration 13 (1970)]. As in Cozzarelli and Huang [Effect of Random Material Parameters on Nonlinear Steady Creep Solutions,” Int. J. Solids Structures 7 (1971)], the problem is separated into two uncoupled problems—a “random temperature problem” and a “random imperfection problem.” Two special cases are fully analyzed: (a) the random parameters are random processes that are only slightly raudom, and (b) the random parameters are random variables that are largely random. Statistical results are obtained for the lateral velocity, bending moment, logarithmic decrement and circular frequency.
Noise Measurement in Reverberant Rooms
Authors: Waterhouse Richard
Published: October 2005

The work of Schroeder, Lubman, Maling, Andres, Tichy, Ebbing, and the author is reviewed. Results for the sound fields set up by single tones, multitones, and bands of noise are considered together with the effects of the discrete- and continuous-space sampling of these fields. The variance for such sampling can be calculated for the above cases, and gives a basis for sampling in such a way as to get results of prescribed accuracy. Some areas that seem to merit attention at present are mentioned. These include (a) reverberation chamber measurement of the power output of a source radiating a steady single-frequency tone, the accuracy to be expected in such measurements, and the comparability of such results with free-field results; (b) the use of moving reflectors, such as rotating vanes, the improvements they afford, and their effect on the sound field and the power radiation of the source.
The Effect of Stationary and Moving Reflectors and Sampling Techniques on the Accuracy of Sound-Power Determination in Reverberation Rooms
Authors: Tichy Jiri , Baade Peter K.
Published: October 2005

The paper summarizes the knowledge on different means and techniques for improvement of sound power and pressure averaging in reverberation rooms. Stationary reflectors, properly located in the nearfield of the source and properly oriented with respect to the floor, can contribute considerably to the scattering of the energy radiated by the sound source. The final effect consists of reduction of the dependence of the radiated sound power on the source position. Also, the effect of positioning of the sound-absorbing materials is reduced. Rotating reflector vanes are important for determining the sound power radiated at single frequencies. There are three effects of the rotating vane: First, the radiation impedance of the source depends on the instantaneous position of the vane and, thus, its rotation provides averaging of the radiated power. Second, the motion of the vane causes fluctuations of the sound pressure at each point of the chamber and, thus, reduces the dependence of the sound pressure on the microphone location. Third, the motion of the vane causes a Doppler effect; an originally single-frequency tone becomes a frequency-modulated tone. Thus, a single line spectrum becomes a multiline spectrum, which reduces the spatial variations of the sound pressure and also increases the number of room modes excited. When averaging the sound pressure, different sampling techniques can be used. The paper discusses the practical aspects of some sampling devices and also the problems of the proper choice of instrumentation for electrical signal processing.
Qualification of Reverberation Rooms for Determination of Sound Power
Authors: Maling G. C. , Ebbing C. E.
Published: October 2005

In practice, many noise sources radiate sound having discrete-frequency components. The desire to use a reverberation room for determination of the sound power radiated by such sources has led to the development of a room qualification procedure that may be used to estimate the adequacy of the test setup and the measurement procedure. The theoretical basis for this qualification procedure is discussed. The causes of the various uncertainties in the measurement of sound power are considered, and it is shown that, in effect, the pure-tone room-qualification procedure allows the total uncertainty to be estimated for a monopole-type sound source. The problems involved with discrete-frequency and swept-frequency qualification procedures are discussed, and experimental qualification data for several rooms with and without vanes and other accessories are presented. Methods of generating the multitude of pure tones necessary for measurement of the room qualification are examined, including the advantages and disadvantages of using prerecorded tapes for this purpose. From both theoretical and experimental studies, it can be concluded that a major factor affecting the qualification of a reverberation room is due to the uncertainty in the measurement of a mean-square sound pressure throughout the room. This factor can be minimized by increasing the number of independent samples that one measures during the sound-power estimate by use of either a sufficiently long continuous microphone traverse or by using multiple microphones. At low frequencies (say, below 500 Hz in a 280-m3 reverberation room), the variability of the soundpower output with source position (change in radiation impedance) becomes the major source of the uncertainty of the sound-power estimate if the sampling of the sound field has been accomplished adequately.
Sound-Power Testing Experiences of an Independent Laboratory
Authors: Kodaras Michael J. , Blanck Michael W.
Published: October 2005

Approximately 150 sound-power level tests have been conducted of unitary and room air conditioning equipment at KAL. This paper submits a complete description of the reverberation rooms used in conducting the tests as well as information regarding the temperature and humidity control systems, room noise levels with and without the control systems operating, and the measurement instrumentation used at KAL. In addition, problems encountered in selecting microphone locations, loading the test specimens, dealing with pure-tone measurements, and other every-day practical problems and their solutions will be discussed. Problems relating to measurement of sound-power level of air handling light troffers, mercury vapor light fixtures, and ballasts will be mentioned. Future changes that will be made to this facility as a result of our experience will be presented.
Influence of External Ear Acoustics on an Impulse Arriving at the Ear Drum
Authors: Price G. Richard
Published: October 2005

The effectiveness of acoustic impulses in producing changes in hearing sensitivity varies greatly as a function of pulse characteristics. In the hope of determining why this is so, an ear model of simple geometry [R. Teranishi and E. A. G. Shaw, J. Acoust. Soc. Amer. 44, 257–263 (1968)] was constructed and instrumented with a microphone at the ear-drum position. Impulses from a gunfire simulator, measured in the free field, were compared with the same impulses arriving at the ear-drum position. At the ear-drum position, the pulses demonstrated an increased peak pressure, a much longer rise time and a greatly increased duration. A Fourier analysis of the pulses revealed a shift of maximum energy from about 500 Hz in the free field to about 3.0 kHz at the ear-drum position, which is the reasonant frequency of the external ear. Damagerisk criteria for impulses should probably reflect the frequency content of the impulses and the transformation produced by the acoustics of the external ear.
The Acoustical Impedance of the Guinea-Pig Middle Ear and the Effects of the Middle-Ear Muscles
Authors: Funnell W. R. J. , Laszlo Charles A.
Published: October 2005

The acoustical input impedance of the guinea-pig middle ear was measured in the frequency range 100–10 000 Hz, using a highimpedance volume-velocity source and a probe-tube microphone. The impedance was measured both in the normal ear and with the tympanic membrane removed; the latter measurement permits accurate characterization of the middle-ear cavities themselves. The data was compared to a slightly modified version of the middle-ear model of Zwislocki [J. Acoust. Soc. Amer. 35, 1034–1040 (1963)], and new parameter values were calculated to match the present data. We also measured the time couraes of transient impedance changes caused by spontaneous contractions of the middle-ear-muscles of the anesthetized animals. These transient changes were compared to the middle-ear-muscle effects predicted by the model. [Supported by the Medical Research Council of Canada.]
Temporary Threshold Shift from Impulses
Authors: McRobert H. , Ward W. D.
Published: October 2005

Temporary threshold shifts were measured for seven listeners after exposure to clicks (one every 3.0 sec) at certain peak levels for varying amounts of time. First, a critical exposure condition was arrived at for each listener, the criterion for this exposure being that combination of peak level and exposure time that would produce 20 dB of TTS0.5 (temporary threshold shift 30 sec after termination of the exposure) at 4 kHz. For two of the listeners, exposure at a peak level of 150 dB for 1 min (20 clicks) was sufficient to produce the required TTS. Four required 152 dB, while the two remaining listeners required 155 dB. Following this, each listener was exposed to clicks at lower peak levels (on different occasions at least 24 h apart). At each level, the exposure time was increased to maintain equal energy during exposure. For each subject, the lower-level exposure produced significantly less TTS. Thus equal amounts of exposure energy do not necessarily lead to equal auditory hazards, at least for impulse noise.
Hearing Impairment in Monkeys after Exposure to Noise
Authors: Stebbins W. C. , Moody D. B. , Johnsson L.-G. , Hawkins J. E.
Published: October 2005

Following determination of their normal hearing thresholds by operant conditioning methods, old world monkeys were exposed to octave bands of noise centered at 500, 2000, and 4000 Hz at levels between 100 and 120 dB SPL for periods of time up to 160 h. Temporary and permanent hearing loss was evaluated daily after each exposure and for a month following the last exposure; the animals were then sacrificed for examination of the inner ear by phase-contrast and scanning electron microscopy. Maximum temporary and permanent hearing loss was found at the center of the exposure band and extended as much as an octave above the center. Temporary hearing impairment of 40–50 dB occurred following an exposure level of 100 dB SPL for 2 h; no permanent changes were observed. At the other extreme, exposures of 120 dB SPL, 8 h daily for a month, produced temporary hearing loss of 90–100 dB at and above the octave band center, and permanent loss of 60–70 dB as measured 1 month after the last exposure. Related histopathology in the cochlea ranged from minimal to fairly extensive hair-cell loss. The size of the lesions was less than anticipated on the basis of the threshold changes. Their location was in general agreement with the place principle. [Research supported by the National Institute of Neurological Diseases and Stroke.]
Cinefluorographic Study of Coarticulation of Pre- and Postvocalic Allophones of /l/ in Consonant Clusters
Authors: Giles S. B.
Published: October 2005

Lateral cinefluorographic films were taken of three subjects at a speed of 150 frames/sec. The subjects, natives of the midwestern U. S. and judged to possess a dialect typical of that region, produced words in which an /l/ allophone was a part of a pre- or postvocalic consonant cluster. Articulatory movements were analyzed by a frame-by-frame tracing of the structural contours through the phonetic sequences under investigation. In prevocalic clusters, articulation of the [l] was shown to coarticulate with the articulatory movement associated with the phonetic element immediately preceding the [l]. The articulation of the phonetic element immediately following the postvocalic [l] coarticulated with the movements associated with the [l]. The degree of overlap or the timing of the sequence of articulatory movements in the clusters was variable.
Coarticulation as an Adjunct to Perception
Authors: Manning W. H. , Beasley D. S. , Beachy T. S.
Published: October 2005

The hypothesis that a unit of speech production would be more accurately perceived as the degree of coarticulation of that unit increased was investigated. Various models of speech production were employed in the creation of an operational definition of “degree of coarticulation.” Sixty subjects listened to 50 randomized monosyllabic two-word phrases, presented under six S/N conditions (−10 to +15 dB, in 5-dB steps). The second word of 25 of the items began with an /st/ blend. In the other 25 items, the first word terminated with the morpheme /s/, while the second word began with the phoneme /t/. The listeners were required to record manually each of the 50 two-word phrases. Mean percentage correct scores for 10 listeners at each S/N condition were calculated. The results revealed that perception was more accurate under the condition representing a greater degree of coarticulation (i.e., /st/ blend). These results support the contention that a relationship exists between perceptual accuracy and degree of coarticulation.
A Spectrographic Study of Allophones of Voiceless Stop Consonants in American English
Authors: Monsen R. , Molter M. , Umeda N.
Published: October 2005

The times of closure and aspiration in /p,t,k/ were investigated using spectrograms of naturally read texts. Most obvious effects in the data are the differences between word-initial and word-final stops and between stressed-syllable-initial and unstressed stops. There are several effects of phonetic environment—notably a shortening of closure time when the stop is preceded by a nasal. Word-initial stops form a class with closure and aspiration times varying proportionately from short duration in function words to long durations for emphatic and prepausal content words with primary stress on initial syllables. Final stops form a class tending toward either long closure times or long aspirations, but not both, depending on the immediate phonetic context. Inside the word, the stops form more tightly grouped classes, dependent on the lexical stress and phonetic environment. In general, the durations of closure and aspiration of the voiceless stops are predictable from the identity of the consonant and from its phonological context.
On Significance of Allophonic Variation in Voiceless Stops; Some Results of Vocal-Cord Instrumentation and Speech Synthesis
Authors: Coker C. H. , Umeda N.
Published: October 2005

A study of allophonic variations of voiceless stops in American English was made by transillumination of the glottis and by modeling in speech synthesis. Variants of phonemes are largely ignored in linguistic studies, on grounds that they are nondistinctive—i.e., insignificant in distinguishing the words that a phoneme string represents. In speech synthesis, however, we find the selection of allophones more crucial. Durations of closure and aspiration time of consonants in otherwise identical phoneme sequences can indeed force clear choices between such phrases as “the spit/this pit,” “at all/a tall,” etc. In measurement of vocal cord area by transillumination, data on the consonants /p,t,k/ show the glottis remaining open wide during the plosive burst and most of the aspiration of strongly aspirated stops, then closing rapidly to begin voicing. In weakly aspirated stops, the cords are kept closed, or nearly so, as if there were simultaneously articulated glottal stops. In stressed-syllable-initial /st/, the cords open wide during /s/ but close during /t/, reaching closure in time to suppress the burst and aspiration. Since the cords are apparently capable of opening or shutting in 30 or 40 msec, variants from 0 to 100 msec in aspiration time must be expressly controlled rather than accidental. Thus we see aspiration-time allophones as systematic (Monsen, Molter, and Umeda, previous abstract), explicitly selected and important for distinguishing word sequences. Whether or not they are nondistinctive, these allophones are not linguistically insignificant.
Sensitive Test of Speech Communication Quality
Authors: Nakatani Lloyd H.
Published: October 2005

Small differences in the quality of various speech samples, all highly intelligible according to articulation tests, were reliably discriminated by a test which determined how easily the speech samples could be heard against a background of interfering speech. The communication quality of a degraded speech was measured by the difference, Q = T − T0, where T and T0 were the intelligibility thresholds for the degraded and high-quality reference speech, respectively. An intelligibility threshold was defined as the value of the signal-to-interference intensity ratio, where the signal speech was 50% intelligible in the presence of interfering speech. Q measures and subjective quality ratings were obtained for speech degraded by low- and high-pass filtering, additive noise, and transmission over a telephone line. The Q measures successfully discriminated differences in speech quality, and they were also monotonically related to the ratings, thereby validating the test for speech quality evaluation. Articulation scores and ratings were not monotonically related, a finding which calls into question the validity of articulation tests for the evaluation of high-quality speech samples.
The Instant of a Syllable: Effects of Differing Sentence Frames
Authors: Boomsliter Paul C. , Hastings George S. , Creel Warren
Published: October 2005

At the 80th convention of this society, we presented a paper indicating that when speaking a simple sentence in time to a metronome, a speaker places one or another specific articulatory action on the timing point within a stressed syllable. Results of an expanded study using 20 readings of each of 38 syllables embedded in each of four different sentence frames (3040 samples) indicate that the principle is valid well past the limits; of the original study and that different sentence structures produce some differences in the principle's application.
New Developments in Metal Working Processes
Authors: Shoh Andrew
Published: October 2005

Recent experiments in sonically assisted metal machining and forming are described. A wide range of vibratory inputs is explored to elucidate the cause and effect relationship. The emphasis is placed on presenting the data in terms of basic physical quantities and on defining the controllable sonic parameters contributory to the process. Specifically, ultrasonically assisted drilling using conventional twist drills is discussed where axial vibratory motion is superimposed on rotational motion of the drill. Novel testing techniques are used to generate and analyze the data. The second part of presentation deals with ultrasonically assisted metal forming where deformation of simple cylindrical specimens is observed as a function of combined static and dynamic stresses. Both studies include a variety of metals.
Ultrasonic Metal Removal
Authors: Devine Janet , Tarpley W. B.
Published: October 2005

The results effected via ultrasonic excitation of the cutting tool in material removal processes such as lathe turning, boring, and twist drilling are discussed. Single-point cutting with ultrasonic-cutting-tool drive results in increased metal removal rates, improved surface finish, and improved machinability of difficult-to-cut alloys. The ultrasonic tool post that can be mounted on commercial lathes uses standard interchangeable cutting tools. A prototype ultrasonic boring bar currently in experimental production use is described. Data and photographs representative of machining aluminum and steel are presented. A fluted twist drill is a poor torsional load-carrying structure, and thus it is significant that power can be delivered to the cutting edges of a twist drill via the vibratory mode to the end that static thrust and mechanical torque are reduced, which is especially significant where drill breakage is a problem. Metal removal rates are increased, chip expulsion is facilitated, and the usual four-six diameters of depth can be increased without drill withdrawal. Ultrasonic twist drilling data are provided for hole diameters up to 916-in. in several materials. Photographs of ultrasonic machining and drilling systems for industrial equipment are presented.
Measurement of Acoustic Powers in the Microwatt-Milliwatt Range
Authors: Rooney J. A.
Published: October 2005

The recent increase in the use of ultrasonics in medical diagnosis has led to the need for methods to measure very low acoustic power outputs in the megahertz frequency range. A system similar to that described by Kossoff [J. Acoust. Soc. Amer. 38, 880–881 (1965)] has been developed which uses a Cahn electrobalance to measure acoustic radiation force on an absorbing target. At present the system can easily detect power outputs of 30 μW. Sources of error and how they can be eliminated in such measurements will be discussed. Recently questions have been raised about the validity of the classical theoretical expression for Langevin radiation pressure applicable to the case of a plane traveling wave impinging on an absorbing target in an open vessel. However, a critical review of the theory using a formulation based on Euler's momentum theorem leads one to the conclusion that the Langevin radiation pressure is just equal to the classical value of the energy density even when nonlinearities of the propagation medium and distortion of waveform are considered. Experimental tests of this theory are in progress. [This work was supported by the HAS Project at the University of Vermont, and by the National Institutes of Health.]