bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of electrodes for speech muscle electromyography
Authors: Konopacki Richard A. , Cole Kelly J.
Published: October 2005

A variety of surface and intramuscular EMG electrodes commonly used in speech research, and a silver-silver chloride (Ag-AgCl) miniature surface electrode we have developed for speech EMG were evaluated by quantitatively comparing charcteristics such as impedance, senstivity, bandwidth, noise, and susceptibility to motion artifact. These characteristics were measured periodically to monitor changes with time. Additionally, experimental subjects rated the electrodes for discomfort and obtrusiveness. The results reveal serious difficulties with the “paint-on” (silver metal-film) variety of surface electrode for most speech EMG applications. While the preferred electrode can vary with the application, hooked wire electrodes, particularly those using platinum-iridium wire, consistently demonstrated superior performance. Where hooked wires are contraindicated, a sufficiently miniaturized high quality Ag-AgCl surface electrode, comparable to the design described in this paper, is often the preferred alternative. [Research supported by NINCDS grant.]
Impulse studies of scattering by finite noise barriers
Authors: Medwin Herman
Published: October 2005

Laboratory studies of shadowing by noise barriers most often use impulse sources, primarily because this permits the separation of reflections from diffractions and it avoids interference from extraneous boundaries of the experiment. A computer implementation of an exact, closed-form impulse theory of diffraction and reflection by plates and wedges has similar advantages: the delta function source permits direct calculation of reflection and diffraction components due to each face and edge of a finite barrier, as well as reflections from the ground, so that the times and amplitudes of all contributions are clearly presented. When the total impulse response is fast Fourier transformed, excellent agreement is found with shadowing losses measured in the frequency domain. Computer optimization of finite barrier design is simple, and double diffraction at a thick barrier becomes physically meaningful by use of a discrete impulse interpretation of Huygens' principle. [Work supported by the Office of Naval Research.]
An acoustical round robin with a difference
Authors: Halliwell R. E.
Published: October 2005

Traditionally, an acoustical absorption round robin requires that a number of laboratories perform similar measurements on the same or nominally the same material and report the results to a coordinating body. Recently the Division of Building Research of the National Research Council Canada completed a different type of round robin, with absorption measurments being made on the same sample, using the same equipment, and performed by the same operators at a number of acoustical laboratories in Canada and the United States. This makes it possible to reduce the variability associated with different measurement procedures so that the variability due to room and diffuser geometry can be studied.
Human auditory development
Authors: Hecox Kurt
Published: October 2005

The purpose of this paper is to review the evoked potential correlates of human auditory development with special emphasis on the brainstem auditory evoked response (BAER). A number of developmental dependencies have been identified in the BAER, including threshold changes, latency changes, absolute and relative amplitude changes, sensitivity to varying rate of stimulation, and age dependent topography. These age dependent phenomena will be reviewed and new data on developmental aspects of adaptation, broadband and narrow-band masking, and frequency specificity will be discussed. Primary emphasis will be placed on the definition of the source of the age dependent changes in the absolute latency of wave V, including the relative contribution of mechanical and neural factors to the observed changes. The picture emerging from these observations is that the determinants of auditory development, as reflected in the auditory evoked response, are multifactorial. Each of these factors has its own time constant and rarely acts independently of the other factors.
What can we learn about small bladder fish by measuring backscattered sound?
Authors: Clay C. S. , Heist B. G.
Published: October 2005

Our paper is limited to the scattering of high-frequency acoustic signals from small bladder fish because that is our data base. The frequencies are above the bubble resonant frequency of the swim bladder. We measure the probability density function (PDF) of fish echoes from fish in situ. Since we use a directional transducer, we also include the beam pattern effect and random locations of fish in the sonar beam. We have measurements of caged fish for which the attitude and behavior are controlled. The PDF of the fish echoes depend on fish behavior and the length of the fish. We fit the two-parameter Rice PDS, i.e., the envelope of a sine wave plus ramdon noise, to the data. For small fish and very quiet fish, the sine wave component is much larger than the random component. Large active fish have a large random component and the PDF tends to the Rayleigh PDF. We are constructing acoustic models of the fish by combining, measured scattering cross sections versus aspect, measured PDF, and behavior. Even though our studies were made at high frequencies the spatial resolution of the single transducer was not large enough to image the fish. It would be a lot easier to measure fish lengths and behavior directly if we had high resolution imaging sonars. [This work was supported by a grant from the Office of Naval Research.]
Natural vibrations of free orthotropic plates
Authors: Caldersmith Graham
Published: October 2005

A simplified model for the bending mode series of free bars combines with an interpretation of the twisting vibration of orthotropic plates to yield an expression for the natural mode frequencies of a free orthotropic rectangular plate, with good low- and mid-frequency predictive power. Differences in the lowest mode frequencies between flat plates and arched violin plates (shells) indicates the effects of arching (plate curvature) on the mode series. The displacement geometry of certain modes deforms the arch much more than that of other modes, and results in dispersion of mode frequencies, an effect which can be related to empirical practice in violin making.
Ultrasonic wave scattering from solids with periodic surfaces: Theory and experiment
Authors: Jungman Alain , Adler Laszlo , Roberts Robert , Achenbach Jan
Published: October 2005

The problem of an ultrasonic wave scattered from solids with periodic surfaces is formulated analytically. This analysis uses an integral representation of the scattered elastodynamic field in terms of the surface displacement of a suitable canonical problem. A digitized ultrasonic spectrum analysis system is used to measure the frequency components of broadband pulse backscattered from periodic surfaces of various solids. Features of the observed amplitude spectra are analyzed based on theoretical predictions.
Frequency dependence of the MLD in forward masking
Authors: Yama Mark F.
Published: October 2005

Detectability for the binaural conditions NOSII and NOSM was compared to that of a reference mortaural system condition (either NOSO or NMSM) in a forward masking paradigm. When signal frequency was varied, the pattern of MLDs obtained was similar to that observed in simultaneous masking: For both the NOSO and NOSM conditions the largest MLDs were obtained for frequencies between 250 and 400 Hz and progressively smaller MLDs were produced as signal frequency was increased above this range. These results suggest that the vector addition of masker and signal may be used to model binaural detection in this experiment, even though masker offset and signal onset were separated by an ISI of 5 ms. One unexpected result was also obtained: for frequencies above 1 kHz detectability in the NOSM condition tended to be about 2 dB worse than that for either the NOSO or NMSM conditions. [Work supported by an NIH National Research Service Award.]
Simultaneous masking and unmasking with bandlimited noise
Authors: Lutfi Robert A.
Published: October 2005

A study was conducted to examine the extent to which simultaneous masking of a tone by bandlimited noise is affected by interactions among spectral components of the noise. Simultaneous masking patterns (signal threshold versus signal frequency) were obtained with three types of maskers: (a) narrow-band noise 50-Hz wide with center frequency fv, (b) pairs of narrow-band noises (50-Hz each band) with center frequencies fl and fu, and (c) broadband noise formed by filling the spectral gap between the two bands of (b). fv was set to 1.0, 1.1, 1.2, and 1.3 kHz; fl was fixed at 1.0 kHz, and fu was varied at 1.1, 1.2, and 1.3 kHz. On both the high-and low-frequency side of the maskers, (b) and (c) produced more masking than the simple sum of the masking by their individual components as measured in (a). For signal frequencies below the masker, adding noise to fill the spectral gap between the two bands of noise in (b) actually resulted in a release from masking. The unmasking is largest (average 10 dB across subjects) where masking by the combination band generated by (b) is most evident. The implications of the results for popular measures of frequency selectivity are discussed. [Work supported by NIH.]
Nonsimultaneous masking and temporal summation in the parakeet (Melopsittacus undalatus)
Authors: Dooling Robert J. , Searcy Margaret H. , Cohen Mark S.
Published: October 2005

Behavioral thresholds for a 15-ms probe tone were obtained for three parakeets in a backward, forward, and a combined forward and backward masking paradigm as a function of masker frequency. For all three paradigms, threshold improved dramatically (∼10 dB) when masker frequency was ±20 Hz of the probe frequency compared to the equal masker and probe frequency condition. In the region of the “tip” of the masking function the Q10 dB values were 140, 20, and 70 for the backward, forward, and combined backward and forward masking paradigms, respectively. The sharpness of tuning in the frequency region of the probe is considerably greater than that found for humans tested with the same stimuli. Probe threshold also varied as a function of masker level and masker duration for both forward and backward masking paradigms. Temporal summation data for short tones and noises are consistent with previous data obtained with longer signals. [Work supported by NIMH.]
Doppler-shift compensation behavior of Pteronotus parnellii parnellii during avoidance of stationary and moving obstacles
Authors: Jen Philip H.-S. , Kamada Tsutomu
Published: October 2005

The Doppler-shift compensation behavior of the CF-FM bats was studied by making three Pteronotus parnellii parnellii fly through an array of seven vertically strung nylon monofilament lines (1.0 mm in diameter) placed near the center of a flight room (12.4 m long, 2.5 m wide, and 2.0 m high). By means of an electric motor. the aluminum frame in which the lines were strung could be made to oscillate in the horizontal direction parallel to the alignment of the obstacles. The maximum amplitude of oscillation was 31 cm and the average speed was 10.3 cm/s. All three bats negotiated moving lines more successfully than stationary ones. The flight speed was about 2.0–2.8 m/s as a bat approached and passed the lines, but it was only about 0.5–0.7 m/s during the final phase of negotiation of lines. Analysis of the emitted signals indicated that each bat appropriately adjusted its emission frequency according to its flight speed during different phases of flight in order to accurately compensate the positive Doppler-shifted echoes. [Work supported by NSF BNS 80 07348 and USPH 1-KO4-NS00433-01.]
Limitations of hearing protection devices (HPDs) as used in real-world environments
Authors: Royster Larry H. , Royster Julia Doswell
Published: October 2005

The effectiveness of hearing protection devices (HPDs) and problems associated with HPD usage have been investigated to-date at over 100 plant sites covering a seven state area. The primary objectives of the study are to identify HPD usage related problems and to develop solutions for the problems defined. The findings have not identified any consistent significant problems. The most common types of problems identified, in order of descending importance, were: discomfort, HPD design limitations, canal irritation, infection, and problems related to HPD fitting, storage and maintenance. In addition, the effectiveness of HPDs in preventing on-the-job temporary threshold shifts has been established to be significantly less than would be predicted using laboratory generated attenuation data. Based on these findings it is concluded that the identified HPD usage related problems can be handled by implementing effective educational programs and administrative procedures.
Measurement of Young's modulus in live tissue excised from dog larynges
Authors: Levi Adrienne P. , Titze Ingo R. , Cooper Donald S.
Published: October 2005

Stress-strain relationships and Young's modulus were obtained from live excised canine vocal fold tissue under two conditions: immediately following stepwise elongation and after 20 min of stress relaxation. The preparations were oxygenated and maintained in a balanced electrolyte solution at a pH of 7.4 and a temperature of 37°C. Tissue viability was tested via electrical field stimulation. Previously reported studies of the viscoelastic properties of vocal fold muscle have used dead tissue, thus limiting the validity of this information for use in the development of biomechanical models of voice production. Young's modulus is compared with values previously obtained on dead vocal fold tissue [Kakita, Vocal Fold Physiology, edited by Stevens and Hirano (1981)].
Vocal fold contact stress during phonation
Authors: Scherer Ronald C. , Titze Ingo R.
Published: October 2005

Investigations of the contact (or collision) stresses of the vocal folds during phonation may be helpful in order to understand and differentiate between normal-pathological-exceptional laryngeal behaviors. Empirical studies of contact stress can also be useful in testing computer simulation models of phonation. Tize and Talkin [Conference on the Assessment of Vocal Pathology, edited by C. Ludlow (1979)] predicted that onset of medial surface collision stress corresponded to onset of medial surface contact area, but that the contact stress should relax before contact area was zero. Similar conclusions were reported in a pilot study using a polyvinylidene flouride transducer [I. R. Titze and R. C. Soberer, Transcripts of the Ninth Symposium Care of the Professional Voice, edited by Van Lawrence (1981)]. The present study uses miniature pressure (strain-gauge) transducers implanted into excised bovine larynges. Advantages and disadvantages of the transducers will be discussed, and signals from various locations within the vocal fold will be compared to contact area signals obtained with an electroglottograph. [Work supported by NIH.]
Relative hazard of weapons impulses as a function of spectrum
Authors: Price G. Richard
Published: October 2005

All damage-risk criteria (DRC) in use predict that impulses from a cannon will be more hazardous than impulses from a rifle, pressure for pressure. Price [J. Acoust. Soc. Am. Suppl. I 62, S95 (1977)] has argued that because of the spectral tuning of the ear, the reverse should be true. Essentially parallel experiments were conducted with 37 cats (74 ears) exposed once to 60 rounds, 3 to 4 s apart, at pressures from 145 to 155 dB (rifle) and 158 to 165 dB (105-mm cannon). Electrophysiological measures of sensitivity (wave P5 from the vertex and N1 from the round window) followed loss from the day of exposure to 2 months afterward. Permanent loss began at about 140 dB for the rifle impulses and 150–155 dB for the cannon. These results are consistent with the prediction and run counter to all rating schemes in use as well as some presently proposed [Smoorenburg, TNO Report 1980-26 (1980)]. Implications of theses findings for existing DRCs and for future developments will be discussed.
Properties of large lexicons: Implications for advanced isolated-word recognition systems
Authors: Zue Victor W. , Shipman David W.
Published: October 2005

A limitation of pattern-recognition-based, isolated-word recognition (IWR) systems is that computation and storage grows (essentially) linearly with the size of the vocabulary. When the size of the lexicon is very large (over 10 000 words), the computation and storage requirements associated with current IWR systems will become prohibitively expensive. Even if cost is not an issue, the performance of these IWR systems for a very large vocabulary is questionable. As part of our goal to design large-vocabulary, speaker-independent IWR systems, we investigated the properties of large lexicons ranging from 1250 words to 20 000 words. We focused on the question: Can properties of the lexicon be exploited in the design of the acoustic analyzer? Our results indicate that the search space can be substantially reduced without having to specify the detailed phonetic characteristics of the lexical entries. For example, if we hypothesize that the acoustic analyzer can only make a distinction between consonants and vowels, then the specification of the CV pattern of a given word can, on the average, prune the 20 000 word lexicon down to less than 1%. If, on the other hand, we hypothesize that the acoustic analyzer can make a six-way distinction, then roughly 13 of the lexicon has unique patterns. The effects of noise (i.e., the introduction of acoustic analyzer errors) and lexicon size will also be discussed. [Work supported by NSF.]
Medical ultrasonic imaging—Principles and instrumentation
Authors: Haylice James
Published: October 2005

Ultrasonic B-scan instruments are used extensively for imaging the internal structures of the abdomen, the fetus, the heart, and the peripheral vascular system. Such diverse anatomical applications have resulted in a diverse set of specialty instruments. These instruments may be divided into two general categories: (a) those based on mechanical motion of the transducer and (b) those based on linear array technology. In the former, one dimension of the two-dimensional image is obtained by moving (usually rotating) a circularly symmetric acoustic beam. In the latter, a nonsymmetric beam is moved not by physical motion of the transducer, but by appropriate phasing of a multielement transducer array. Each technique has its own set of advantages and disadvantages. This paper presents some of the basic physical principles of ultrasonic propagation and how they impact the design of these imaging devices. Particular attention will be given to contrasting the physical principles of the two categories and the limitations imposed. Representative images illustrating the important imaging characteristic will be presented.
Ultrasonic nondestructive evaluation of layered porous metals
Authors: Chamuel Jacques R.
Published: October 2005

Experimental results from the propagation of ultrasonic waves in high porosity copper foam are presented. The difficulties and tradeoffs encountered in ultrasonic NDE of porous layered metals are discussed. The experimental results to be presented include: effects of copper foam crushing on sound wave velocities, compressional velocity anisotropy, Young's modulus as function of porosity compared with other published data, attenuation coefficient measurements, wave propagation in nonuniform materials, and effects of known voids and delaminations. The data originated from a small study to determine the feasibility of ultrasonic NDE of a porous metal heat exchanger. Correlations between the thermal, elastic, and electrical properties of porous materials are also briefly discussed.
Nondestructive evaluation of subsurface flaws
Authors: Varadan V. V. , Varadan V. K. , Pillai T. A. K. , Thompson R. B. , Shu D.
Published: October 2005

Ultrasonic NDE is a convenient tool for detecting subsurface flaws in structural parts since the eddy currents technique is unsuitable when the flaw is more than a millimeter below the surface. Further, in most applications it is not possible to make measurements by bonding the transducer directly to the part to be tested due to difficult geometry. In this paper we propose an analytical method to study the scattering of waves from a subsurface flaw in an elastic half-space that interferes a fluid half-space (i.e., the part to be tested is immersed in water). The numerical results so obtained will be compared with experimental results for subsurface oblate spheroidal (flat cracks) cavities and the results will be critically analyzed to obtain information about the size and depth of the flaw.
Vibrating plates as musical instruments
Authors: Rossing Thomas D.
Published: October 2005

Vibrating plates are the source of sound in many percussion instruments and also serve as sound radiators in most string instruments. In string instruments the plates vibrate with small amplitude and thus exhibit linear behavior. In some percussion instruments, on the other hand, the initial amplitude may be large enough to introduce nonlinearity. Nonlinear behavior, for example, is largely responsible for the pitch glide noted in certain Chinese gongs [T. D. Rossing and N. H. Fletcher, J. Acoust. Soc. Am. Suppl. 1 70, S23 (1981)]. Plates can exhibit nonlinearities of either the hardening or softening type, depending upon their exact shape and state of stress. The modal frequencies of circular plates vibrating in the linear range can be fitted to a relationship f = c(m + bn)k, where m and n are the numbers of nodal diameters and nodal circles. By proper choice of c it is possible to satisfy Chladni's law (b = 2, k = 2) over quite a wide range of frequency in flat plates. Nonflat plates require different choices of b and k.
Sitar spectrum properties
Authors: Benade A. H. , Messenger W. G.
Published: October 2005

The main strings of a sitar are tuned to pitches corresponding closely to F3♯, C2♯, G2♯, G3♯, G3♯, C4♯, and C5♯ (i.e., in 4ths, 5ths, and octaves). Playing is predominantly on the F3♯ string, the tonic (sa) being at the 7th fret (C4♯). There are also 11 sympathetic strings tuned to the notes of the raga. The measured and calculated inharmonicity is far less than that of Western stringed instruments. Sitar strings are thin, giving small stiffness inharmonicity and low wave impedance that reduces random inharmonicities from bridge/belly resonances. String length variations from first mode rolling and/or sliding on the curved bridge profile produces FM and AM sidebands of ±f1 from the upper partials. These components join with both plucked and sympathetic string partials to give harmonically related narrow-band clumps. The resulting tone has complex time behavior but well-marked pitch. Tuning to just frequency ratios is required since the beats arising from excitation of a mistuned string are not smeared by roughness due to inharmonicity. Raman's observation that plucking at L/4 need not remove the 4th partial from the tone is confirmed. Bridge-generated FM/AM provides part of the explanation; shock excitation of sympathetic strings via the bridge provides the rest.
A technique for improving detection and estimation of signals contaminated by under ice noise
Authors: Dwyer Roger F.
Published: October 2005

Recent analyses of FRAM II arctic data have shown that under ice ambient noise can be at times highly impulsive and non-Gaussian. The analyses included time domain statistical measurements which were consistent with previously reported results of experiments made within the Canadian Arctic Archipelago. New findings of frequency domain estimates of complex skew and kurtosis and cumulative distribution functions, measured in 2-and 10-Hz resolution cells at the output of a discrete Fourier transform, also indicate the existence of strong non-Gaussian noise. It is known that the ability to detect and estimate signals contaminated with non-Gaussian noise using conventional processing is degraded compared with optimum techniques which utilize knowledge of the noise statisticcs. Results comparing the performance of conventional and nearly optimum signal processing methods are presented using the FRAM II data. [Work supported by Naval Material Command.]
Influence of random errors in clustering on beamforming of a linear array
Authors: Quazi Azizul H. , Fay John W.
Published: October 2005

Random errors which include amplitude, phase errors, and element failures cause a beam response degradation such as an increase in side-lobe level, beam-pointing errors, and loss in directivity. In this paper we present results of systematic investigation of the effects of random errors on the beamforming performance of a linear array that includes different shading coefficients, clustering, and directional elements. Analysis and simulation results show that using a directional element, clustering, and various weights reduce the degradation of side-lobe level due to random errors. Also discussed are the different tradeoffs necessary to achieve the desired beam response with different weighting, clustering, and directional elements in the presence of random errors. [This work sponsored by Naval Sea Systems Command.]
Lateralization and loudness of high-frequency tones under masking
Authors: Perkins Mark E. , Pavel M.
Published: October 2005

The apparent location of a 4000-Hz tone presented to both ears will depend on the relative intensity of the signals. The position of the image can be affected by addition of noise in one of the ears; the apparent location will shift toward the ear without noise. This effect of noise on lateralization has some similarity to partial masking. We compared the effect of noise on lateralization and loudness by examining a property of the partial masking data called shift invariance [M. Pavel and G. J. Iverson, J. Acoust. Soc. Am. 69, 1126–1131 (1981)]. Using a transformed up-down method in 2IFC paradigm, subjects adjusted the level of a masked tone in one channel in order to center the image of a tone in quiet presented in the other channel. As expected, these data exhibit “recruitment”-like behavior familiar from studies of partial masking of loudness. The data suggest that shift invariance holds for the lateralization data and therefore provides a convenient means of relating the loudness matching and lateralization tasks.
A predictive model for binaural advantages in speech intelligibility
Authors: Zurek P. M.
Published: October 2005

This paper presents a model of binaural advantages in speech intelligibility applicable to anechoic conditions in which speech is masked by a single noise source, with speech and noise sources both located in the horizontal plane. First, frequency- and azimuth-dependent sound-pressure transformations (from Shaw's summary of amplitude measurements and Woodworth's equation for phase) are applied to obtain third-octave signal and noise spectra at each ear. Next (following Levitt and Rabiner), the effective S/N ratio in each band is increased by the masking-level difference, which is approximated with an equation (from Colburn's model of binaural interaction) that describes MLD dependence on relevant stimulus parameters. Monaural and binaural performance are then predicted using Articulation Theory (Kryter). Predictions are in reasonable agreement with data from seventeen studies of the effects of source azimuth and listening mode (monaural or binaural) on intelligibility. The model provides a quantitative framework for analyzing binaural advantages and for assessing the practical benefits of binaural hearing. [Work supported by NIH.]
Binaural horizontal plane localization: Spectral cues as a factor
Authors: Musicant Alan D. , Butler Robert A.
Published: October 2005

Binaural localization performance with broadband noise or 4-kHz high-pass noise was investigated under two conditions. An unoccluded pinna condition was compared to performance in a pinna cavity occluded condition. The external meatus was open. Loudspeakers were placed at 15° intervals from 360° through 270° to 180° azimuth. Subjects were asked to identify the loudspeaker from which a sound originated. Results indicated profound disturbances when the pinna cavities were occluded. The occurrence of front-back reversals increased to approximately 40% for all positions with a high-pass noise stimulus. With a broadband noise, only sound sources in the front were transposed to the rear. Accuracy, defined in terms of either proportion correct or error score, decreased significantly (p < 0.01) when the pinna cavity was occluded. A paramount role for spectral cues in binaural directional hearing is postulated. [Work supported by NIH.]
Wave effects and pressure distribution in the ear canal near the tympanic membrane
Authors: Stinson M. R. , Shaw E. A. G.
Published: October 2005

The complicated geometry of the human tympanic membrane and adjoining portion of ear canal can be expected to affect the flow of acoustic energy into the middle ear at frequencies greater than 10 kHz. To explore the implications of this geometry we have studied the acoustical behavior of a series of experimental cavities with shapes chosen to characterize the various acoustical factors that could be anticipated. The presence of the eardrum was simulated by the inclusion of a plastic or paper film of appropriate size and location. Preliminary experiments indicate that the penetration of the incident acoustic wave into the wedge-shaped volume representing the final 10 mm of ear canal is strongly frequency-dependent, and that between 10 and 20 kHz the apparent plane of reflection moves inward by approximately 6 mm. Measurements of sound pressure distribution in this region indicate that pressure variations greater than 15 dB can be expected across the human tympanic membrane at 15 kHz. Existing theoretical models will need to be modified if they are to be relevant above 10 kHz.
Vibration isolation: A retrospective prospective perspective
Authors: Sykes Alan O.
Published: October 2005

Over the past three decades, a substantial investment has been made by government and private industry in developing an improved understanding of the vibration isolation problem and new vibration isolation techniques. This paper presents a personal view of what has been accomplished, discusses recent analytical and experimental studies both here and abroad, identifies problem areas requiring further investigation, and looks through a smoky glass toward the future.
Finite element analyses for resilient mount design
Authors: Nowak Theodore J.
Published: October 2005

Paper discusses how to improve mount performance and more reliably predict mount characteristics using finite element computer analyses. Alternate finite element approaches, i.e., plane strain, axisymmetric, three-dimension, etc., are discussed as to their suitability for typical mount configurations. Several grid models including deformed grids and stress-strain contour plots are illustrated.
Eikonal calculation of resonance frequencies and modal density for bending waves on an inhomogeneous plate
Authors: Keefe Douglas H. , DeJong Richard G.
Published: October 2005

The general equation for bending waves on an inhomgeneous thin plate in which the plate thickness, mass density, Young's modulus, and Poisson's ratio are slowly varying over the plate may be solved by means of the eikonal approximation. We have considered the case where the plate thickness h varies. The eikonal approximation is applicable when |∇h|/kh is small compared to unity, where the bending wavenumber is k. This implies that the accuracy increases for the higher order modes. At sufficiently high frequencies, the resonance frequencies for bending waves on a plate may be determined from the condition that the total phase shift from one end of a plate to the opposite end is π radians greater than the next lowest mode. Consider a rectangular plate whose lengths in the x and y directions are a and b, respectively, and whose thickness varies linearly along the x direction as h(x) = h0 (1 + αx/a), −a/2 < x < a/2. When no cross modes are present in the y direction (the inhomogeneous beam case), the modal density is equal to that of a homogeneous plate of thickness h0(1 − α2/16) for small α2. A tapered plate of average thickness h0 acts like a homogeneous plate whose thickness is slightly less than h0, and this statement applies qualitatively when the cross modes in the y direction are present. Comparison of the exact eigenvalues for the lowest two-dimensional mode of a simply supported tapered plate with the predicted eikonal approximation as a function of a/b) and plate taper α will be presented. The modal density of an inhomogeneous plate calculated in this fashion is useful in statistical energy analysis applications to complex structures.
The guitar frequency response
Authors: Caldersmith Graham
Published: October 2005

The guitar frequency response is found to be a good predictor of two important parameters of guitar tone: initial level of the partials and initial level decay of the partials. A high initial level normally gives a rapid initial level decay, but under some conditions the higher level may more than compensate for the initial level decay and thus give a tone a longer duration. The condition of the strings was found to be much less significant than the frequency response of the guitar body.
Radiation from cylindrical shells at the neighborhood of the ring frequency
Authors: Harari Azriel
Published: October 2005

For many submerged cylindrical vehicles, there is a marked increase in the acoustical radiation from the structure at the neighborhood of the ring frequency. Several aspects of the shell dynamic characteristics that relate to radiated noise at the neighborhood of the ring frequency are considered here. The ratio between the wavelength of the shell and the wavelength of an acoustic fluid, the admittance level of an infinitely long cylindrical shell, the energy propagation along the cylindrical shell, and the mode shape of a finite cylindrical shell with flexible ends are studied.
Vocal tract effects in wind instrument regeneration
Authors: Benade A. H. , Hockje P. L.
Published: October 2005

Wind players are much concerned with vocal tract influences on tone production. Laboratory study has been inconclusive, in part from inadequate theoretical formulation. A reed valve is opened and closed by the pressure difference (pm − pM) across it: pm in the instrument's mouthpiece, pM in the player's mouth. The reed transconductance A = ∂u/∂(pm − pM) depends on its natural frequency ωr, and its damping, becoming large near ωr. The condition for oscillation is A[(Zm + ZM)//Zr] ⩾ 1. We note that the reed impedance Zr is paralleled by the sum of Zm and ZM. Oscillation requires Im(Zm + ZM) ≠ 0, with sign depending on the low-frequency sign of A (positive for woodwinds, negative for brasses); whence woodwinds play with ω ⩽ ωr, brasses with ω ⩾ ωr. These results extend to large amplitude (mode-coupled) regimes of oscillation in the familiar way. Available data show resonance bandwidths of ZM are much larger than those of ZM (with smaller magnitude fluctuations), explaining the difficulty of direct measurement of musical effects. During tonal startup on long instruments (e.g., horn tuba), Zm changes as successive reflections build up the standing wave. By itself Zm does not generally satisfy the regeneration condition during onset, thus giving a crucial role to the vocal tract. Results of experiments in progress will be presented. [Work supported by NSF.]
Index of refraction of first sound in liquid helium
Authors: Pasierb F. , Kojima H.
Published: October 2005

The index of refraction of first sound in superfluid He-4 which was filled in porous medium was measured as a function of the porosity. The porous medium was made by sintering glass beads (180–210 μm diameter). The measured index of refraction was 1.24 and 1.94 when porosity was 36% and 9.6%, respectively. The observed porosity dependence will be compared with other experiments and with a recent theory [D. L. Johnson and P. N. Sen, Phys. Rev. B 24, 2486 (1981)]. [Work supported by Schlumberger-Doll Research.]
Influence of material compressibility on the effective modulus of elastomer layers with voids
Authors: Timmerman Nancy S.
Published: October 2005

A one-dimensional model, for normal propagation of compressional waves in elastomer layers with cylindrical holes has been generalized to include bulk compressibility effects. The model addresses static and dynamic properties of the layer, in terms of dynamic Young's modulus, Poisson's ratio, and solidity, the fraction of surface area which consists of elastomer. The effective modulus, used in calculations of layer wave speed and impedance, is nearly Young's modulus for low solidity and approaches the dilational modulus as the solidity approaches unity. The former can be a lossy modulus, while the latter is generally lossless. The solidity increases with static load, and this, in turn, increases the effective modulus and decreases the loss factor. Such pressure effects are derived as a function of static Young's modulus. Some comparisons with experimental results are shown.
The use of the Middle Latency Response (MLR) for assessing low-frequency auditory thresholds
Authors: Brown D. Douglas
Published: October 2005

Several investigations have suggested using the MLR to test low-frequency hearing thresholds (i.e., 500 Hz). Recently, a new stimulus paradigm has been proposed [R, Galambos et al., Proc. Natl. Acad. Sci. 78, 2643–2647 (1981)] that increases the detectability of the MLR at low sensation levels. In the past, the MLR has been regarded as being relatively unaffected by sedation or sleep. We are investigating this evoked potential with normal hearing adults, and find that, contrary to previous reports, it can be affected by sleep. That change can show considerable inter-subject variability. Specifically, there is a significant reduction in the response amplitude for a number of the subjects, which could possibly affect the accuracy of this evoked potential in determining auditory thresholds. We have also begun to monitor the EEG in an attempt to correlate MLR changes with specific stages of sleep. Our findings will be summarized in the presentation.
Inharmonicity of wound guitar strings
Authors: Houtsma Adrian J. M.
Published: October 2005

Wound guitar strings are known to “go dead” after several hours of playing. Increased inharmonicity of string partials is thought to be the primary contributing factor, making exact tuning of strings impossible. Increased inharmonicity with age is mostly due to changes in mass distribution rather than changes in stiffness. String aging can be artificially induced by repeated stretching and releasing of a new string. Measurements of the frequencies of the first ten partials in standard brass-wound steel guitar strings show that inharmonicity is significantly increased by repeated stretching. The inharmonic effect of stretching can be greatly reduced, however, if the strings are stress relieved by heat after winding.
Spanish intonation in declarative sentences
Authors: Signorini Angela
Published: October 2005

The present paper attempts to describe the overall intonation pattern of Spanish declarative sentences. The global F0 movements were quantified in the F0 curves. The starting point, the peaks and final point values were obtained from the curves. Results showed that all the sentences under study could be sorted into at least three different forms. Form I showed a raising-falling movement with only one pitch accent. This generally occurred in the shortest statements. Form II showed two pitch accents, the first in the raising slope and the second in the falling. The body, between the pitch accents, remained quite stable. Form III resembled a concatenation of two type I forms. The falling slope of the first form is not as low as the final falling slope. Depending on the criterion followed for the interpretation of this dent and the intonation unit adopted for segmentation, form III will be considered as a series of two forms I or as a form II. In the latter case, the F0 movement in the body would not be relevant for the intonation pattern and could be considered the acoustic correlate of the prosodic feature boundary.
Development of lingual control
Authors: Ostry David J. , Feltham Rosemary F.
Published: October 2005

In both speech and limb movements, the maximum velocity of the movement is correlated with the distance traveled. In adult lingual movements, this is accompanied by a systematic relationship between displacement and the interval from oral release to the point of maximum velocity [D. J. Ostry and A. Parush, J. Acoust. Soc. Am. Suppl. I 71, S56 (1982)]. The development of these relationships in speech was examined in English speaking children between three and 11. The data were gathered using pulsed ultrasound to monitor tongue dorsum movements during repetitions of alternately stressed CV syllables. Findings were that displacements and maximum velocities were greater for stressed than for unstressed vowels. By age three reliable correlations were obtained between maximum velocity and displacement on both raising and lowering movements of tongue dorsum. Subjects six years or older also showed a constant interval from oral release to maximum tongue lowering velocity across differences in voicing, but like adults, estimates differed with stress. The implications of these findings to speech control and its development are discussed.
Nasal coarticulation of pharyngeal and glottal consonants: A deductive account
Authors: Bladon Anthony , Al-Bamerni Ameen
Published: October 2005

The general observation [e.g., Bell-Berti, Stat. Rep: Speech Res., Haskins Labs., 46 (1980)] that velum height decreases as articulatory constriction decreases is examined in the context of pharyngeal and glottal obstruents in Arabic and Kurdish. Investigated by transillumination of the velopharyngeal port, these consonants are seen to be always produced with a substantial velopharyngeal opening. Moreover, the “nasality” exhibits a coarticulatory spread to adjacent vowels. A deductive account of consonant features could use considerations of articulatory synergy and biological bias to predict such findings, in particular the requirement that /ħ ʕ h/ should be specified as [+ nasal]. In addition, such an account might predict that for reasons of perceptual sufficiency the temporal spread of velopharyngeal opening from a pharyngeal or glottal consonant would be less extensive than from a nasal consonant. This is in fact shown to be the case.
Perceptual and acoustic invariance for place of articulation in diffuse stop consonants
Authors: Gewirth Letitia , Blumstein Sheila E. , Lahiri Aditi , Kurowski Kathleen
Published: October 2005

A recent investigation of acoustic invariance for place of articulation in diffuse stop consonants [Lahiri and Blumstein, J. Acoust. Soc. Am. Suppl. 1 70, S39 (1981)] has shown that current theories of acoustic invariance cannot distinguish labial from dental stops. Analysis of natural speech utterances suggested that there was acoustic invariance for labial and dental consonants, but based on the relative changes in the distribution of energy at high and low frequencies from the burst release to the onset of voicing. In this study, we attempted to determine whether the relative changes in the spectral characteristics elaborated by Lahiri and Blumstein would play a role in the perception of place of articulation in diffuse stop consonants. Prototype CV syllables ([b d] in the context of [i e a o u]) were generated based on natural speech tokens. The gross shape of the spectrum was manipulated first at the burst onset, then at the onset of voicing, such that the stimulus configuration had the spectral properties for labial or dental consonants while the formant frequencies and transition values were appropriate to the contrasting place of articulation. Results showed perceptual shifts for both labial and dental consonants in the context of [i] and [el, but not for the back vowels. Changing the prototype stimuli for the latter by using a mid-value F2 in the test stimuli did have some perceptual effects on place of articulation. [Supported in part by an NIH grant.]
The influence of vocal frequency and intensity on the perception of speech rate: Natural speech samples as stimuli
Authors: Bond Ronald N. , Feldstein Stanley , Brady Elizabeth , Simpson Sallie
Published: October 2005

Previous studies by the authors found, using masked speech samples, that the perception of speech rate was influenced by both vocal frequency and intensity. The study reported here replicated the previous one but used unmasked, or natural, speech stimuli and examined the effects of speaker gender. Using one speech sample each from a male and female speaker, three levels of frequency and intensity were factorially combined to produce nine stimuli for each speaker. The actual speech rate of each stimulus was 150 wpm The 18 stimuli were randomly ordered with each preceded by a standard stimulus. Twenty-nine judges rated each stimulus, relative to the standard, on four 7-point, unipolar scales: speech rate, pitch, loudness, and duration. The results indicate that the perceptions of speech rate were positively related to frequency but not intensity. Judgments of pitch and loudness were positively related to frequency and intensity, respectively, and judgments of duration were inversely related to frequency. Finally, the influence of frequency on perceived speech rate differed for the male and female speaker.
Error measures for tomographic estimates of sound velocity
Authors: Calderone Denise , New Ronald , Porter David L. , Eisler Thomas J.
Published: October 2005

Inversion of perfect (error-free) tomographic data produces an imperfect estimate of the sound speed anomaly. The estimate is in error because the unknown function is sampled by a finite number of rays. This imperfection of the measuring system can be interpreted either in terms of resolution or in terms of bias error. In certain instances, the bias interpretation offers significant advantages, particularly when one wishes to quantify the error in the estimate. In this paper, we develop the latter interpretation. Our treatment employs various moments of the resolution kernels of the Backus-Gilbert theory. Methods for calculating bias error bounds as combinations of constants, dependent only on the tomographic configurations, and bounds on the higher order derivatives of the estimated function will be shown. Calculated bounds for a sample configuration will be presented. Use of these bias constants in comparisons of configuration performance will also be discussed.
An improved procedure for evaluating the annoyance of small arms ranges
Authors: Luz George
Published: October 2005

By combining annoyance data published in studies of small arms ranges in Sweden and Australia with other data on the acoustics and levels of small arms fire published in limited distribution Army and Navy technical reports, the author derives a computer program for predicting the impact and annoyance of small arms ranges firing ammunition up to 25 mm. Copyright free copies of the computer program written in BASIC will be available for interested participants.