bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of an alternating magnetic field system for transducing articulatory movements in the midsagittal plane
Authors: Cohen M. H. , Perkell J. S.
Published: October 2005

The performance of an alternating magnetic field system for transducing articulatory movements is evaluated. Devices have been constructed to: (1) precisely position a transducer along an axis perpendicular to a transmitter and (2) move a transducer through a circle of adjustable radius, both with arbitrary amounts of transducer tilt. Testing has shown that: (1) Individual transducers have slightly different characteristics, requiring transducer-specific field calibration, gain and tilt-correction factors. (2) Accuracy, repeatability, and resolution of measurements are better than 0.25 mm. (3) Measurements are not affected by: amalgam dental fillings, off-midsagittal plane transducer placement of up to 5 mm and proximity of 2 transducers of as little as 8 mm. (4) Circles produced with a radius as large as 75 mm at transducer tilt angles of 0, +, and − 30 deg are concurrent. (5) Absolute distance measurements can be affected by the precision with which a transducer is oriented when being attached to an articulator. A pilot vowel-repetition experiment has demonstrated the usefulness of the system. The advantages of an alternative scheme for tilt correction are discussed. [Work supported by NIH Grant No. NS04332.]
Observation of the palato-lingual contact in the cases after hemiglossectomy by use of dynamic palatography
Authors: Suzuki Noriko , Michi Kenichi , Yamashita Yukari
Published: October 2005

The dynamic palatograph (DP) employed in this study is an electric device capable of displaying and recording constantly changing palato-lingual contact as a function of time, utilizing a thin plastic artificial palate incorporating 63 electrodes. The DP was applied to investigate palato-lingual contact before and after hemiglossectomy to three subjects with carcinoma of the tongue. The palatogram and speech sound were simultaneously recorded and synchronized with a sound spectrogram. The following findings were obtained: (1) Before hemiglossectomy, nearly normal patterns were observed in all cases. (2) After hemiglossectomy, abnormal patterns were found in all cases, though the results differed among the three cases according to the volume of the resection. In two cases, where less than half of the tongue was resected, contact areas tended to increase at the frontal part of the palate in one case, and at the side corresponding to the nonresected side of the tongue in the other. In the third case, where more than half of the tongue was resected, contact areas were very small.
An EMG study of levator palatini during vowel production
Authors: Dixit R. Prakash , Henderson Janette B. , Bell-Berti Fredericka
Published: October 2005

EMG activity of the levator palatini muscle and voice were recorded while a native speaker of Hindi repeated 10 CVC nonsense utterances, where C was the voiceless alveolar fricative /s/ and V was one of the following vowels /i ı e ɛ ə ɑ ɔ o ɷ u/. Preliminary examination of the data indicates that there is almost always some suppression of the levator palatini activity for the vowel as compared to the surrounding consonants. The degree of levator suppression seems to vary with tongue height, progressively increasing from high to low vowels. Further, levator suppression for the back vowels is somewhat less than for the heightwise comparable front vowels. The data will be presented and discussed. [Work supported by NIH Grant NS-13617 and BRS Grant PR-05596 to Haskins Laboratories.]
Physical mechanisms in stellar pulsations
Authors: Cox Arthur N.
Published: October 2005

Stars evolve from their births to their deaths by converting their store of hydrogen to helium, and then much of this helium is fused to heavier elements such as carbon, oxygen, and up to iron. During this evolution, the stellar mass may decrease by a stellar wind mass loss, the radius usually greatly increases, and the radiation luminosity emitted at the surface grows until the stellar death results in a very small compact object. During this evolution, there are often several stages when the structure of a star is unstable against pulsations. These pulsations are observable and indicators of the internal details of its structure. Six of these self-excitation mechanisms, which produce limited amplitude pulsations, will be discussed and demonstrated. Three deep-seated ones are the modulated nuclear fusion reactions at the stellar centers, the possible Kelvin-Helmholtz instability at the surface of a rapidly rotating core of the star, and oscillation of convective eddies which has a restoring force due to a composition gradient in deep layers. Three mechanisms which operate in tbe outer layers are the oscillations of convective eddies restrained by a strong magnetic field, and the thermodynamic effects of blocking and hiding of the radiation luminosity due to the ionization of the abundant elements, hydrogen and helium.
Gravitational waves: A new window for astronomy
Authors: Michelson Peter F.
Published: October 2005

Gravitational waves were predicted more than 50 years ago by Einstein as a consequence of the general theory of relativity. Because of the weakness of the gravitational interaction, efforts to directly detect gravitational waves have focused on astrophysical sources rather than terrestrial sources. In laboratories around the world, second-generation cryogenic acoustic detectors and laser interferometric detectors are being developed with sensitivity and bandwidth sufficient not only to verify directly the existence of gravitational waves, but also to study the received waveforms. Because the gravitational radiation emitted by an astrophysical source contains information about the source that is orthogonal to information obtained from electromagnetic signals, the direct detection of gravitational waves will open a new window for astronomy. In this review, the likely astrophysical sources of gravitational radiation and the technology of second-generation acoustic detectors will be discussed.
Vibrations in the environment of large future telescopes
Authors: Pearson E. T.
Published: October 2005

As larger telescopes are designed with more servo-controlled elements, the chance of undesirable vibrations increases. What are the sources of the vibrations and how can the telescope be designed to avoid problems? If problems can be created by acoustical and mechanical vibrations, might there also be a use for input vibrations?
Measurement and specification of the human ear canal geometry
Authors: Stinson Michael R.
Published: October 2005

Above 8 kHz the sound pressure transformation along the human ear canal (a central issue in the development of high-frequency audiometry) depends very much on the details of the canal geometry. In addition to canal volume and length, which provide an adequate description at lower frequencies, one must account for the curvature of the ear canal and the variation of cross-sectional area along the canal length. In particular, calculation of the sound pressure transformation requires specification of cross-sectional areas perpendicular to a curved axis that follows the “center” of the canal. A photogrammetric technique has been developed that accurately determines the geometry of human ear canals and specifies it in this format. Stereoscopic photographs of cadaver ear canal castings are analyzed to define a large number (up to 1000) of coordinate points on the surface of each casting. A numerical procedure extracts the curved, center axis that passes through the points and calculates cross sections normal to this axis. The geometry of one ear canal has been sucessfully obtained using the technique, and measurements on several more are under way.
Interactions among otoacoustic emissions, and associated threshold microstructures
Authors: Tubis Arnold , Jones Kenneth , Long Glenis R.
Published: October 2005

Third-order intermodulation distortion products or cubic difference tones (CDTs) in the ear canal may be generated from nonlinear cochlear interactions between two external tones, an external tone and a spontaneous otoacoustic emission (SOAE}, or two (primary) SOAEs. In the last case [E. M. Burns et al., Hearing Res. 16, 271–278 (1984)], the frequencies of the CDTs are found to be close to, but not always coincident with, frequencies of minima in the threshold microstructure, in contrast to the frequencies of the primary SOAEs. We have investigated this situation further by: (1) entraining one of the primary SOAEs with a variable frequency (f) tone and (2) determining f for which the ear canal CDT level relative to that of the entraining tone is maximal. We generally find this value of f to correlate well with a threshold fine structure minimum. These results, along with related cochlear model simulations, are consistent with previous observations that CDT SOAEs tend to occur if the CDT frequency is sufficiently close to that of an evoked or spontaneous otoacoustic emission. [Work supported by NINCDS.]
Error correction and concealment in digital recording
Authors: Locanthi Bart N.
Published: October 2005

No medium is perfect. The imperfections range from accumulations of dirt on a film or disk to the microscopic absence of the recording medium on its supporting substrate. In digital reproduction, bits, or even words, are lost with potentially spectacular results. The nature of these defects, and the technologies that have been developed to overcome them, will be discussed and demonstrated.
Pitch detection on a programmable vibrotactile aid for the deaf
Authors: Eberhardt Silvio P.
Published: October 2005

A vibrotactile aid capable of real-time speech processing has been developed. Three microprocessors are used for, respectively, speech sampling and data reduction, pattern matching, and generation of vibrator drive signals. Data reduction is performed by generating data records at each zero crossing of the speech signal. Records consist of the interval since the last zero crossing (ZCI) and average amplitude during that interval. A pitch detector has been implemented on the aid. The algorithm is based on the observation that consecutive pitch periods have similar ZCI and amplitude structures. Pattern matching is performed by comparing adjacent strings of ZCI and amplitude values. Sum-of-difference correlation values are low when the strings correspond to actual adjacent pitch periods. The pitch search window is adaptively narrowed after voicing has been detected. The detector shows no tendency to lock onto other harmonics or formants. Results of comparisons with other pitch detectors in several white and babble noise conditions will be presented. [Work supported by NIH, NSF, NIHR.]
Lateralization of dichotic noise bursts: Trading onset against offset disparity
Authors: Small Arnold M. , Kuk Francis
Published: October 2005

We previously reported on the lateralization of a sound image associated with either onset or offset disparity of dichotically presented uncorrelated noise bursts [J. Acoust. Soc. Am. Suppl. 1 70, S91 (1984}]. We found that (1) onset and offset disparities are both effective cues, with onset being more potent, (2) lateralization is toward the leading ear for onset and toward the lagging ear for offset disparity, (3) shorter stimuli exhibit stronger lateralization effects, and (4) equalization of loudness of the dichotic stimuli does not alter lateralization (thus ruling out simple loudness as the cue mediating the effect). The present research investigated the interaction of onset and offset disparity by covaryin 8 each. Thus the dichotic noise bursts could differ in onset or offset disparity or both, with either ear leading. Listeners quantified image location by positioning a slider in a diagram of a head. The results indicated that a trading relation existed. That is, a given image position could be achieved by a variety of simultaneously present onset and offset disparities. Onset disparity was by far the stronger influence.
Signal onset times and the precedence effect
Authors: Rakerd Brad , Hartmann W. M.
Published: October 2005

A consistent finding in our studies of auditory localization in rooms has been that brief tones with abrupt onsets and offsets are localized far more accurately than are sustained tones with slow onsets [W. M. Hartmann, J. Acoust. Soc. Am. 74, 1380–1391 (1983); B. Rakerd and W. M. Hartmann, J. Acoust. Soc. Am. Suppl. 1 75, S88 (1984)]. The purpose of the present study was to explore the contribution of signal onset rate to this effect. In a room with left-wall acoustical reflections of brief delay (mean delay time = 1.5 ms), we assessed localization performance for sustained tones (500 Hz, 60 dB) with onsets of 5000, 1000, 500, 100, 50, 10, 5, and 0 ms. The accuracy of subjects' (n = 4) localization judgments increased monotonically with rate for all onsets less than 100 ms. Testing with a subset of the onset times showed that a similar pattern of results is obtained in rooms with other paths of reflection (ceiling, mean delay = 1.5 ms) and with other delay times (left wall, mean delay = 9 ms). We hypothesize that signal onsets must be shorter than 100 ms if they are to trigger operation of the precedence effect in rooms, and that within that regime their effectiveness increases with increasing rate. [Work supported by NIMH.]
Perceived pitch (tonality) of five unfiltered nonsense syllables and their identification and quality assessment through six 1-oct filter bands
Authors: Johnson Carole E. , Asp Carl W.
Published: October 2005

Research involving the perceived pitch (tonality) [M. M. Peterson and C. W. Asp, J. Acoust. Soc. Am. Suppl. 1 52, S146 (1972) and C. W. Asp, J. S. Berry, and C. S. Bessell, J. Acoust. Soc. Am. Suppl. 1 64, S20 (1978)] and optimal octaves in phoneme perception [E. E. McKenney and C. W. Asp, J. Acoust. Soc. Am. Suppl. 1 51, S122 (1972) and R. M. Miner and J. L. Danhauer, J. Am. Audiol. Soc. 2, 163–168 (1977)] has supported the notion that phonemes may be “frequency specific.” The purposes of this study were to have normal-hearing listeners (1) rate the perceived pitch of five unfiltered nonsense syllables with phonemes homogeneously grouped according to a pitch model [C. W. Asp, J. S. Berry, and C. S. Bessell, J. Acoust. Soc. Am. Suppl. 1 64, S20 (1978)]; and (2) identify and assess the quality of the nonsense syllables each filtered through six 1-oct filter bands with center frequencies of 250, 500, 1000, 2000, 4000, and 8000 Hz. Results indicated that (1) the nonsense syllables could be ranked according to low to high perceived pitch (i.e., /mumu, vovo, lala, keke, and sisi/); (2) identification scores for the filtered nonsense syllables were high except when filtered through the two lowest bands (i.e., 250 and 500 Hz); and (3) quality assessment of the filtered nonsense syllables revealed “optimal octaves” for perception of each nonsense syllable. Results are discussed in terms of the rankings of perceived pitch of the unfiltered nonsense syllables in relation to their filtered “optimal octaves.” Implications for aural rehabilitation will be discussed.
Bottom penetration from a range- and depth-dependent oceanic sound duct
Authors: Miller J. , Nagl A. , Überall H.
Published: October 2005

In a fundamental paper [F. B. Jensen and A. Kuperman, J. Acoust. Soc. Am. 67, 1564 (1980)], the penetration of sound propagating upslope in a wedge-shaped ocean, into the ocean bottom, has been calculated using the parabolic-equation method; subsequently, this problem was treated by Evans [J. Acoust. Soc. Am. 74, 188 (1983)] using the slab method, as well as by others. The mentioned work assumed an isovelocity water duct and isovelocity bottom. Previously [A. Nagl, H. Überall, A. J. Haug, and G. L. Zarur, J. Acoust. Soc. Am. 63, 739 (1978)], we have developed an adiabatic mode theory approach to sound propagation in a range- and depth-dependent environment; this has now been generalized to include mode coupling. When applied to the Jensen-Kuperman wedge problem, we reproduce their results (downward directed bottom penetration). This is generalized by introducing sound-speed gradients, which leads to very important results: A positive (realistic) bottom gradient causes the bottom-penetrating sound to travel along the ocean floor, rather than downwards into the bottom. This effect has far-reaching consequences. [Work supported by the Office of Naval Research, and by the Singer Company—Link Simulation Systems Division.]
Some new results for ray transmissions in a wedge-shaped ocean
Authors: Rousseau T. H. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

The influence of a sloping bottom on cw ray transmissions in an isospeed channel is investigated. Bottom angles up to about 3° are considered, and regular perturbations off horizontal bottom results are employed. Accurate analytic approximations to ray-geometric quantities are derived. Then, sloping bottom influence on per-ray travel time and transmission loss is examined. Significant variations are shown to occur, such as travel time changes of more than 200 ms over ranges of about 6 km. Per-ray transmission loss is found to be strongly influenced by bottom slope. Variations of more than 20 dB are illustrated. Sloping bottom effects on the total acoustic field are examined also. A comparison of the influences on travel time of one model of a shallow-ocean front and the sloping bottom is made. The sloping bottom effect can induce travel time changes more than 300% larger than the frontal effect. [Work supported by ONR.]
Recent developments in acoustic intensity
Authors: Rasmussen Gunnar
Published: October 2005

The development of intensity measurement techniques has increased the demand for knowledge about the transducers used and for improved calibration techniques. The phase response of transducers is very important. Knowledge about the behavior of transducers at higher frequencies is especially significant for the determination of the effective acoustical spacing between transducers. The use of two, four, or six transducer probes is required in order to obtain the total energy density at a point. The estimation of the active intensity and the reactive intensity of a wave field depends on proper use of instrumentation and calibration technique and proper use of the transducers in a wave field. The configuration in which the transducers is mounted plays an important role in obtaining good data. Development in instrumentation enables the use of gating techniques, which improves the signal enhancement. By combining information in frequency and time domain a better understanding of source behavior is achieved.
Energy streamlines for sound sources
Authors: Waterhouse R. V. , Feit D.
Published: October 2005

These streamlines are constructed so that at each point on one, the sound intensity vector is tangential to the streamline. They thus show the direction of flow of the sound energy in an acoustic field. Energy streamlines are formally analogous to the velocity streamlines familiar in fluid mechanics, and for axially symmetric sources represent contours of the Stokes stream function. The latter function can be computed from the intensity function, as the two are analytically related in a skew differential manner. Examples of the streamlines are given for the circular piston source in an infinite rigid baffle and the water-loaded plate driven by a line or a point source. The streamlines are chosen so that equal energy flows between each adjacent pair of streamlines. The sound pressure field is irrotational, but the sound intensity field is rotational, and interesting patterns of circulating energy, including vortices, occur for some source configurations.
Surface acoustic intensity distributions on vibrating plates driven by distributed forces
Authors: Keltie R. F. , Peng H.
Published: October 2005

The two-dimensional acoustic intensity distributions on the surface of vibrating plates driven by multiple point forces and by finite-sized force distributions have been examined analytically and experimentally. Calculations and measurements were made using a 5- × 5-ft. aluminum plate of 0.25-in. thickness, simply supported around the periphery. Results are shown for the specific case of two harmonic point forces, acting at numerous different locations on the plate's surface. One parameter of interest concerns the relative phasing between the two forces, and computational results are presented for the cases of in-phase, 90° out-of-phase, and 180° out-of-phase forces. In addition, acoustic intensity patterns associated with disk force and line force excitations are presented. The results are discussed in terms of frequency and in terms of the relative importance of different portions of the plate, including the regions near the forces, and the regions corresponding to edge mode and corner mode radiation. [Work supported by NSF.]
Source localization using the PE method
Authors: Tappert F. D. , Nghiem-Phu L. , Daubin S. C.
Published: October 2005

The most important information for source localization is oceanographic knowledge supplied to a powerful machine that numerically computes acoustic Green's functions rapidly and accurately. By this means the distorting effects of the oceanic medium and its boundaries can be removed, thereby rendering the ocean transparent. Then targets can be detected, localized, and classified at low S/N ratios as though they were moving in free space, leading to the result there is “no place to hide.” As an illustration of this approach, we discuss in detail the solution of the problem of passive narrow-band acoustic localization (an instance of the inverse source problem) following the pioneering work of Bucker [J. Acoust. Soc. Am. 59, 368–373 (1976)], in which beamforming was made obsolescent. Using the PESOGEN (Parabolic Equation SOlution GENerator) computer system [J. Acoust. Soc. Am. Suppl. 1 75, S26 (1984)] and an algorithm based on the generalized principle of reciprocity, we have demonstrated theoretically that targets can be accurately and reliably localized at long ranges and low S/N ratios using sparse configurations of sensors.
Reconstruction of a complex acoustic field from its real or imaginary part
Authors: Wengrovitz Michael S. , Frisk George V. , Oppenheim Alan V.
Published: October 2005

In underwater acoustics, the sound pressure field in a horizontally stratified, range-independent medium due to a continuous-wave point source can be described by a Hankel transform of the depth-dependent Green's function. Although the total field consists of both outgoing and incoming components, a reasonable assumption is that the incoming components can be neglected. This assumption is the basis for a number of synthetic field generation techniques such as the Fast Field Program (FFP) [F. R. DiNapoli and R. L. Deavenport, J. Acoust. Soc. Am. 67, 92–105 (1980)]. It is shown that the condition that the field consists only of outgoing components implies a relationship between the real and imaginary parts of the field. An implication is that the real (imaginary) part of the pressure field can be reconstructed from the imaginary (real) part. An algorithm for performing this reconstruction is presented and examples of its application to synthetic and experimental acoustic fields is discussed.
Annoyance from audible infrasound
Authors: Møller Henrik
Published: October 2005

For several years it has been known that noise at low and infrasonic frequencies can cause considerable nuisances. The annoyance cannot be predicted by A-weighted sound levels since the A-curve nearly removes the infrasonic frequencies completely and it also seems to attenuate the low audio frequencies too much. Recent work on equal loudness and equal annoyance contours indicates that the annoyance from infrasound is closely related to the loudness sensation. The use of a weighting curve based on the loudness and annoyance curves is suggested. The ISO/DIS 7196G1 curve might be a proper choice. The applicability of this curve is demonstrated. The experiments involve pure infrasonic tones as well as one-third octave bands. The consequence of simultaneously occurring audio frequency noise is also demonstrated.
Broadband rotor noise in atmospheric turbulence
Authors: Giegg S. A. L.
Published: October 2005

This paper describes the development of a prediction method for broadband noise from wind turbines. In this method, two of the more important source mechanisms (unsteady lift and unsteady thickness noise [D. Hawkings, J. Acoust. Soc. Am. Suppl. 1 63, S21 (1978)] can only be predicted if the inflow turbulence intensity and length scale are known. By using a suitable model of the atmospheric boundary layer, these parameters can be estimated, as a function of height above the ground, using the measured wind speed and a ground surface roughness parameter. The sound propagating to the geometric nearfield of the rotor is then calculated by evaluating the source level at 20 azimuthal positions and five radial positions in the rotor disk plane. Other source mechanisms, such as trailing edge noise and the noise from separated flow, are also included. The results are compared with measurements on 5-, 20-, and 80-m-diam wind turbines.
Infrasound: Incidence and significance in motor cars
Authors: Haddad Sam D.
Published: October 2005

During the last two decades there has been much interest in the effects of infrasound on people. This is partly due to claims made by some scientists that infrasound could cause effects such as intestinal irritations, throbbing in the head, nervous breakdowns, certain allergies, and other unpleasant phenomena of modern life found in industrial cities. Early work [J. E. Green and F. Dunn, J. Acoust. Soc. Am. 44, 144–145 (1968)] concluded a positive correlation between infrasonic thunderstorms and road accidents and other deviant behavior. Others have addressed the question “Does infrasound make drivers drunk?!” With the possible effects on road safety this paper aims to assess the incidence of infrasonics in transport environments with particular reference to European passenger cars. It was found that infrasonic sound pressure levels (ISPL) were proportional to vehicle speed, window opening, and vehicle size. Also driving with a fitted roof rack tended to increase ISPL by as much as 20 dB. It was also found that under most adverse driving conditions ISPL never exceeded 110 dB which is below human performance thresholds. It seems therefore that the original significance placed on the incidence of infrasound in cars was misplaced. Also it is concluded that further work needs to be done to establish the effects of exposure duration on human performance thresholds and to include the higher low frequencies as well. [Fundamental research project conducted by S. D.Haddad and Charles Marks at Loughborough University, England in 1980 with further investigations by S. D. Haddad concluded in 1983.]
A statistical model for predicting the probability of complaints from army weapons noise
Authors: Luz George A.
Published: October 2005

U.S. Army environmental noise assessments use a statistical average (DNL) to evaluate the impact of heavy weapons noise on nearby residents, but experience has shown that variability above the average is the source of complaints. To assist environmental planners and range control officers in predicting complaints from a specific configuration of range and weapon, a BASIC language program short enough for a personal computer has been developed. Users begin by choosing the weapon from a menu and after defining the coordinates of the firing point, target, and observer, they have the option of: (1) entering a noise level and receiving the probability of that level being exceeded at the observer's location, or (2) entering an exceedance level and receiving the noise level associated with that exceedance level. Noise levels are then compared with the criteria used in the successful complaint management program at the Naval Surface Weapons Laboratory, Dahlgren. Onsite blast noise measurements taken over the past decade are used to demonstrate the predictive validity of the model.
Dynamics of the bowed string
Authors: Schumacher Robert T.
Published: October 2005

The bowed string is acted upon by a force, applied at the surface of the string, that is nonlinear in its dependence on string velocity. Consequently, the string's dynamics are affected by rotational motion of the string as well as by the translational motion that largely determines the force that drives the bridge. A review of the theory of this nonlinear bowed string dynamics will be given, followed by a discussion of the effects of rotational motion on starting transients and playing frequency. Experimental results will be shown from a bowing machine, capable of highly reproducible motion, that include measurements of the string's rotational motion during bowing. [Work supported by NSF.]
Analysis of performed transitions in orchestral instruments
Authors: Strewn John M.
Published: October 2005

The region between performed notes was examined in nine instruments (flute, bass flute, piccolo, clarinet, oboe, bassoon, trumpet, violin, and cello). On each instrument, eight intervals (2nd, 3rd, 5th, 7th, ascending, and descending) and two playing styles (tongued/untongued, bow change/no bow change) were digitally recorded. Using a computer, the recordings were analyzed for time-varying power and time-varying spectrum (phase vocoder). Analysis of as many as five recordings of a given interval and playing style showed that the performer could easily replicate a given transition, so the recordings were judged as representative. In the tongued (bow change) case, the notes were farther apart, the amplitude dip between the notes (except in the cello) was greater, and spectral changes were more extensive than in the nontongued (no bow change) case. This pattern was not significantly influenced by variation in the size of the interval, the direction of the interval, or the instrument performing. [Work performed at CCRMA, Standord University, and supported by SDF.]
Calculations of ocean ambient noise over a continental slope
Authors: Del Balzo D. R. , Authement M. J. , Mire C. T.
Published: October 2005

Computer calculations of slope effects on surface noise at 100 Hz were made using the NORDA high-angle, implicit finite difference acoustic field model. A geoacoustic description of a continental margin, which is typical of the east coast of the U.S., was chosen for analysis (vertical slope of 2.8 deg and covered by 500 m of silt). In order to enhance the effect of bottom interaction, a Summer Sargasso Sea sound-speed profile was used. The calculations indicate the presence of a deep noise notch over the slope (for certain basin and shelf noise generating locations) which is deepest near the ocean surface (25 dB) and which decays with depth. The potential for signal-to-noise ratio gain is suggested. [Work supported by NAVAIR.]
Measurements of the nonlinear tuning curves of Helmholtz resonators
Authors: Wu Junru , Rudnick Isadore
Published: October 2005

The tuning curves of several Helmholtz resonators terminating impedance tubes have been measured for sound-pressure levels at the necks of the resonators of from 18.8 dyn/cm2 to 1.36 × 104 dyn/cm2. It is found that the peak frequencies of the tuning curves shift to higher frequencies as the sound level is increased. The shifting is believed to be due to the fact that the end correction of a Helmholtz resonator is a function of the sound level at the neck; the higher the sound level, the smaller the end correction [U. Ingard, J. Acoust. Soc. Am. 25, 1037 (1953)]. A peak frequency shift as high as 20% has been observed. [Work supported by ONR.]
Nonlinear evolution of three-dimensional vortical disturbances in a slowly varying waveguide
Authors: Herbert K. , Kuo S-L. , Thompson C.
Published: October 2005

The instability of the Stokes boundary layer generated by an acoustic disturbance in a two-dimensional waveguide having a slowly varying height is examined. As the disturbance amplitude becomes finite in value, it is found by Thompson [J. Acoust. Soc. Am. Suppl. 1 77, S 48 (1985)] that the Reynolds stress causes the solution for the disturbance field to bifurcate supercritically from that obtained by linear stability theory. Therefore, special attention is given to the problem of weakly nonlinear evolution of 3-D vortical disturbances. The disturbance amplitude is shown to be governed by the solution of the nonlinear Schrodinger equation ∂2A (x,τ)∂x2 + (γ1x + T1γ2)A + γ3A|A2| = γ4∂A∂τ, where A is the disturbance amplitude, and γ1, γ2, γ3, and T1 are parameters dependent on the local behavior of the acoustic wave, as well as the duct geometry. The solution for time-spatial evolution as well as the global behavior of the disturbance field, will be presented.
Measurement of the 2f1-f2 combination tone in a subject with a noise-induced hearing loss
Authors: Takahashi Gall A. , Collins M. Jane
Published: October 2005

A cancellation technique was used to measure the 2f1-f2 combination tone in a subject with a bilateral asymmetric noise-induced hearing loss. The study was designed to determine the effects of primary frequency and level on the perception of the 2f1-f2 combination tone. The f2/f1 ratio was 1.2, and six primary tone pairs were chosen such that their frequencies fell below, in, and above the frequency region of the notched hearing loss. In the subject's poorer ear, the 2f1-f2 combination tone was not perceived when the combination tone frequency fell in the region of the hearing loss. When the primary frequencies fell in the region of the hearing loss, the 2f1-f2 combination tone was not perceived for input levels of 50 and 60 dB SPL but was for 70 dB SPL.
Basic auditory capabilities and resolving power for phonemes
Authors: Espinoza-Varas B. , Watson C. S.
Published: October 2005

Efforts to relate performance on speech test to general auditory abilities have yielded conflicting evidence. One possible reason is that the resolving power for individual psychoacoustic dimensions is related more closely to the ability to resolve acoustic details of individual phonemes, than to global speech perception as assessed by the overall percent of tokens correctly identified on a speech test. Auditory capabilities were measured with a battery of psychoacoustic tests [Watson et al., J. Acoust. Soc. Am. Suppl. 1 71, S73 (1982)]. Speech perception ability was studied with seven subtests of the CUNY Nonsense Syllable Test, NST (presented in quiet, 33 dB SPL). Indices of speech perception were derived for each individual phoneme, overall for each subtest, and overall for the seven NST subtests. Results from 34 normal listeners showed: (1) large differences in identification accuracy of phonemes within a subtest, which are not reflected in the overall measures; (2) strong biases towards specific phonemes within a subtest; and (3) differences in identification of an individual phoneme depending on the specific subtest in which it occurs. Thus the overall measures of speech processing are poor indicators of the ability to resolve specific phonemes. This result, together with the fact that phonetic distinctions are cued by multiple (redundant) cues, suggests that correlations between overall speech measures and auditory capabilities may be expected to be moderate or low. [Supported by NIH and AFOSR.]
SDLB adaptation and an approximation of Steven's power law
Authors: Weiler Ernest M. , Sandman David , Agnello Joseph , Balzer Gene
Published: October 2005

Initial curve fitting efforts having yielded similar results, data from four studies [E. Jerger, J. Acoust. Soc. Am. 29, 357–363 (1957); T. Palva and J. Karja, J. Acoust. Soc. Am. 45, 1018–1021 (1969); E. M. Weiler, M. Loeb, and E. A. Alluisi, J. Acoust. Soc. Am. 51, 638–643 (1972); and E. M. Weiler and J. D. Hood, Audiology 16, 499–506 (1977)] were combined to encompass intensities from 20 to 80 dB SL at 1 kHz. All studies used the classic method of simultaneous dichotic loudness balances (SDLB} as described by Hood [Acta. Oto-Laryngol. Suppl. 92 (1950)] and Small [Modern Developments in Audiology, edited by J. Jerger (Academic, New York, 1963)]. A regression line was fit to the log values of stimulus intensity and log adaptation (dB). Converting to the form of Steven's power law, the resulting constant K by this approach was 0.9449 and the exponent of intensity N was 0.73953. For loudness magnitudes, N has often been reported as about 0.60.
Finite element analysis of shock-induced hull cavitation
Authors: Felippa Carlos A. , DeRuntz John A.
Published: October 2005

This paper describes the theoretical formulation and computational implementation of a method for treating hull cavitation in underwater-shock problems. In addition, the method can be applied to the analysis of submerged structures that contain internal fluid volumes. In the present implementation, the doubly asymptotic approximation (DAA) serves to simulate a radiation boundary that is located away from the fluid-structure surface at a distance sufficient to contain any cavitating region. The enclosed fluid is discretized with volume finite elements that are based upon a displacement-potential formulation. An explicit time-integration algorithm is used to advance the solution in the fluid-volume region, implicit algorithms are used for the structure and DAA boundary, and a staggered solution procedure has been developed to treat the interface condition. Results for two example problems obtained with the present implementation show close agreement with those obtained by other methods.
Assessing the hazards of impulse noise superimposed on background noise
Authors: Henderson D. , Hamernik R. P.
Published: October 2005

Impulsive noise, either in the military or industrial setting, rarely occurs without some substantial background noise. This paper reviews a series of animal experiments which show synergistic interactions between relatively “safe” continuous and impulsive noise. In all the experiments, chinchillas were either exposed to (1) 60 min of background noise (either 2–4 kHz or 0.5–1 kHz) at levels ranging from 95 to 89 dB; (2) 50 spark discharge-generated impulses with peak sound pressure levels ranging from 158 to 137 dB and A durations of 32 to 64 μs; (3) various combinations of (1) and (2). The animals' hearing was measured immediately after the exposure, and at regular intervals over a 30-day period. After 30 days, the cochleas were analyzed for losses of sensory cells. The results show that certain combinations of individually “safe” impulse and continuous noise can (1) produce a synergistic interaction; (2) that these interactions behave systematically as either the level of the impulse or the continuous noise is reduced; and (3) that the interaction effect is enhanced as the frequency spectra of the two noises begin to overlap. The results of the experiments will be discussed in terms of the mechanisms of noise-induced hearing, implications for measurement of noise environments loss, and the implications for public health standards. [Work supported by NIOSH.]
Hearing protector attenuation as influenced by frequency and time variation of the noise
Authors: Johnson Daniel L. , Smith Myron D.
Published: October 2005

Over a decade ago, Jim Botsford proposed two innovative concepts that provide the basis of this study. First, he proposed correcting the attenuation of hearing protectors by a “C-A” adjustment [J. H. Botsford, Sound Vib., 32–33 (Nov. 1973)]. Using three separate time history dosimeters, set to 5-s periods, the C-weighted and A-weighted levels at the shoulder were measured; also, the level under the muff was recorded. The results show that most of the time the C-weighting outside the muff is the best predictor of the A-weighted level under the muff when used with a single value of noise reduction. Another concept of Botsford was the TTS meter, in which the intermittency pattern of a noise could be assessed [J. H. Botsford, Am. Ind. Hyg. Assoc. J. 32, 92–95 (1971)]. Harris and the first author further enhanced this concept by providing a TTS-based intermittency correction factor to adjust a noise dose [D. L. Johnson and C. S. Harris, Proc. Noise Expo, Chicago, IL, 16–122 (1979)]. Using this adjusted dose, our current data indicate better performance by muff-type hearing protectors than simply calculating inside and outside average noise levels might predict. We also noted that a person's voice can disproportionately influence the attenuation predicted by an under the muff measurement. We believe that Botsford's early concepts are still valid and technology now exists which can make his ideas useful.
Computer-steered microphone arrays for sound transduction in large rooms
Authors: Flanagan J. L. , Johnston J. D. , Zahn R. , Elko G. W.
Published: October 2005

The quality of sound pickup in large rooms—such as auditoria, conference rooms, or classrooms—is impaired by reverberation and interfering noise sources. These degradations can be minimized by a transducer system that discriminates against sound arrivals from all directions except for that of the desired source. A two-dimensional array of microphones can be electronically beam steered to accomplish this directivity. This report gives the theory, design, and implementation of a microprocessor system for automatically steering a two-dimensional microphone array. The signal-seeking transducer system is implemented as a dual-beam, “track-while-scan” array. It utilizes signal properties to distinguish between desired speech sources and interfering noise. The complete automatic system has been tested in anechoic and medium-sized auditorium environments, and its performance is discussed.
Ultrasonic depth page for liquids under high pressure
Authors: Zuckerwar Allan J. , Mazel David S. , Hodges Donald Y.
Published: October 2005

An ultrasonic depth gauge of novel design continuously measures the level of a liquid subjected to a high pressure (up to 6000 psi), as is sometimes required for effective transfer of the liquid. The gauge operates as a composite resonator, fabricated from a standard high-pressure plug. A flat-bottomed hole is machined into the plug along its center line. An ultrasonic transducer is bonded rigidly to the interior surface of the bottom wall, while the exterior surface is in contract with the liquid. Although the bottom wall is designed to satisfy the pressure code (ASME Code for Pressure Piping B31, 1980 edition), it is still sufficiently thin to permit ready excitation of the axisymmetric plate modes of vibration. The liquid depth is measured by a conventional pulse-echo technique. The external threads of the plug serve as the primary pressure seal. A prototype gauge, constructed with a 3/4-in. stainless steel plug and a 10-MHz piezoelectric transducer, was tested successfully in a 600-gallon water vessel at pressures up to 5200 psi.
A coupled finite difference model for n fluid-loaded, free-flooded, thickness-polarized, piezoelectric cylindrical shell transducer
Authors: Chiou Chwei-Chi , Rogers Peter H.
Published: October 2005

This paper presents a coupled finite difference model for a fluid-loaded, free-flooded, thickness-polarized, piezoelectric cylindrical transducer. In order to find the vibration response of this shell when subjected to a sinusoidal voltage drive, the Donnel's thin shell equations of axisymmetric free vibration of a circular cylinder are coupled with the piezoelectric canonical equations and a surface Helmholtz integral model for the acoustic radiation reaction. The acoustic loading and the piezoelectric effects are thus considered to be external loading factors in the vibration equations. Solutions for the velocities are then used as the inputs to a previously developed farfield radiation program (SHIP) to get the source levels over the frequency range, which depends on the specifications of the transducer under consideration. The validity of this model is verified by comparing the computed source levels with the experimental data for transducers of two different materials and four different geometrical dimensions.
Wave-vector-frequency filtering characteristics of multilayer plate systems via two-port methods
Authors: Stepanishen Peter R.
Published: October 2005

The wave-vector-frequency (k − ω) filtering characteristics of multilayer systems provide a measure of the signal and noise transmission through such systems as sonar domes or flow noise decouplers. A two-port method of analyzing the k − ω filtering characteristics of multiliquid layer and elastic plate systems will be presented. Both liquid and elastic layers are represented using two-port parameters based on straightforward multidimensional Fourier transform methods. Timoshenko-Mindlin plate theory is utilized for the elastic layers. Multilayer configurations are readily addressed via the cascading of two-port matrices. Numerical results for the k − ω filtering characteristics of several multilayer configurations will be presented. The physical phenomena which contribute to the structure of the transfer function in k − ω space for the various configurations will be discussed.
Generation of vocal-tract shapes from formant frequencies
Authors: Wold Donald C.
Published: October 2005

A microcomputer program has been developed to generate midsagittal vocal-tract shapes from the corresponding formant frequencies. The concept of formants is usually presented in textbooks and references for courses in the science of sound. The frequencies of these resonances are used to obtain the vocal-tract configurations for different vowel positions of the tongue. Ladefoged et al. [J. Acoust. Soc. Am. 64, 1027–1035 (1978)] have devised an algorithm that uses only the first three formant frequencies of vowels for generating vocal-tract shapes as seen on midsagittal x-ray diagrams. Ladefoged et al., gave a procedure for estimating the width of the vocal tract at different positions, but not the two-dimensional shape. In order to graph the midsagittal vocal tract shapes with a microcomputer having limited memory, an arbitrary, standardized, upper surface of the vocal tract was constructed. The equation of a catenary was used as a reference curve. A parametric form was found useful for generating graphs and relating path length to distance along the vocal tract.
Spectrographic analysis of vowels in Down's syndrome speech
Authors: Kimelman Mikael D. Z. , Swift Edie , Rosin Margaret M. , Bless Diane M.
Published: October 2005

The speech of individuals with Down's syndrome is often considered to be worse than that of individuals with other forms of developmental disabilities. The present study was initiated to shed light on a broad range of communication abilities of individuals with Down's syndrome. Preliminary evidence in the form of spectrographic analysis of vowels will be presented. Several factors including formant patterns and variability will be reviewed. These data will be discussed with respect to possible explanations for this population's poor speech intelligibility. [Work supported by Award from the National Institute of Education No. NIE-G-81-0009.]
Lip/jaw coordination with larynx in the speech of stutterers
Authors: Borden Gloria J. , Armson Joy
Published: October 2005

Laryngeal movements were inferred from slow and fast (filtered) impedance changes recorded by an electroglottograph and lip/jaw movements from the deflections of an LED attached to the lower lip. Stutterers and control subjects repeated two, four-digit numbers five times each or until they were judged to be fluent. The interactions of the lip/jaw lowering at the release of the [f] constriction in the words “four” and “five” with vocal fold adduction for the vowel and the onset of voicing were analyzed by making selected temporal measures in both the displacement and the velocity traces. Results of the data analyzed thus far indicate functional relationships: i.e., the lip/jaw system coordinates with vocal folds for the [f] by closely timing oral constriction release with maximum vocal fold opening, and for the vowel by closely timing peak velocity of lip/jaw opening with peak velocity of vocal fold adduction. Stutterers show aberrant laryngeal-supralaryngeal interactions as well as instances of “normal” coordination in the midst of stuttering. [Work supported by NIH.]