bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of interaural decorrelation in multitone complexes
Authors: Stellmack M. A. , Grange A. N. , Aguilar C. M.
Published: October 2005

The present study examined the ability of listeners to detect interaural decorrelation of multicomponent complexes. Just-noticeable correlation differences for a reference correlation of + 1.00 were measured as a function of the number of components in the complex (3,5,9) and bandwidth of the complex (20, 40, 80 Hz). All components were equally spaced and centered at 753 Hz. A 2IFC procedure was used, in which the first interval consisted of a complex with an interaural correlation of + 1.00 (i.e., a diotic complex), and the second interval contained either a diotic complex or an interaurally decorrelated complex. The complexes were decorrelated by generating interaural phase differences (IPDs) in the individual components. The lowest frequency component had an IPD of 0, while the remaining components had equal magnitude IPDs that were of opposite sign for adjacent components. Thus, for each n-component complex, n − 1 components carried an IPD in the decorrelated intervals. The starting phases of the components were randomized between intervals. All of the observed threshold interaural correlations were greater than 0.99 in all conditions. Thresholds were lowest for the 80-Hz bandwidth conditions for three, five, and nine components. At each bandwidth, thresholds increased with increasing numbers of components. [Work supported by NIH.]
Piezoelectric sensors and actuators for active vibration damping using digital control
Authors: Varadan V. V. , Hong S.-Y. , Sung C.-C. , Varadan V. K.
Published: October 2005

All air-borne, water-borne, and space structures suffer from undesirable vibrations. Conventional methods of passive damping would require addition of masses comparable in many cases to that of the structure itself; the control is not broadband and significantly alters the performance of the structure. Light-weight, rapid, and multimode control of the vibrating structure is possible by the use of piezoelectric sensors and actuators and digital feedback algorithms. The results of vibration control experiments on prototype structures, such as clamped cantilever beams, truss structures, such as T beams, Y beams, shafts undergoing torsional vibrations, etc., using PZT sensors and actuators will be presented. Different types of digital control methods have been implemented, each with its own advantages and disadvantages. The damping ratio with and without control is calculated and compared with experimental results. Damping is increased anywhere from 0.3 to 3 orders of magnitude. Different poling arrangements for the piezoelectric sensors and actuators have been studied to obtain maximum sensitivity to the type of stress and strain fields in the vibrating structure under consideration. The same ideas have also been used for active cancellation of sound fields using coatings that incorporate sensors and actuators.
Research on the noise generated by turbulent boundary layer flow over an axisymmetric body with a flat nose
Authors: Shang Zhe
Published: October 2005

The noise generated by hydrodynamic flow over an axisymmetric body with a flat nose is described quantitatively. Flush-mounted hydrophones were used to measure that part of the turbulent boundary-layer pressure fluctuations that propagates as true sound. Power spectra of sound pressure were measured in a 200-Hz to 150-kHz frequency range over a wide range of Reynolds numbers (U∞D/ν 2.52×10, where D is the diameter of the body) for the model operating in the China Ship Scientific Research Center 03B water tunnel. The power spectra of the noise measured in the laminar flow regions correspond little to those measured in the transition and fully developed turbulent regions of the flow. Free-stream turbulence intensity and transition regions on the model were measured by using a laser-Doppler velocimeter. The transition regions have been compared with the computation results and found to agree rather well with experiment. In addition to the experiment, 12 axisymmetric bodies are calculated and compared with the experiment. Results indicate that when the prismatic coefficient and DF/D are fixed, the model has fairly good flow properties. When DF/D is fixed and the prismatic coefficient is decreased, or the prismatic is fixed and the DF/D is decreased, the separation point or transition point is delayed.
Speech intelligibility measures on level-dependent hearing protectors
Authors: Abel Sharon M.
Published: October 2005

This research compares signal detection and speech perception in subjects wearing either conventional level-independent muff-style hearing protectors (E-A-R 3000 and BILSOM 2315) or their level-dependent counterparts (E-A-R 9000 and BILSOM 2390). Three groups of 20 subjects, two with normal hearing, aged 20 to 35 yr and 40 to 60 yr, and one with moderate bilateral sensorineural hearing loss, in the older age category, are being assessed. The measurements include detection thresholds for one-third octave bands within the audible frequency range, consonant discrimination, and the recognition of words in sentences, in quiet and in a background sound pressure level of 75 dB cable swager noise. Speech items are presented at 80 dB SPL. The results obtained thus far for normal subjects indicate that, except for the BILSOM 2390 at 4000 Hz, detection in noise remains the same or is slightly enhanced in the occluded relative to the unoccluded condition. While speech intelligibility decreases precipitously in noise, the wearing of three of the devices, the E-A-R muffs and BILSOM 2315, mitigates the effect. Aging, without concomitant hearing loss, is not a statistically significant factor. [Work supported by Ont. Min. Labour.]
Interpretation of shallow gas-charged sediments on seismic records
Authors: Hovland Martin
Published: October 2005

Porewater and gas seepages through the seafloor have become the target of frontier research over the last decade. Such seepages occur worldwide and at water depths to over 5000 m. The seep locations are often identified by use of high-resolution shallow seismic systems. Data examples and case studies from the North Sea, the Skagerrak, offshore Mid Norway, and the Persian and Mexican Gulfs are presented and discussed. Such terms as “acoustic turbidity,” “acoustic voids,” “enhanced reflectors,” and “wipe out zones” will also be discussed.
Field experiences in the direct measurement of anomalous acoustic behavior of gas-rich sediments
Authors: Tinkle Anthony R. , Meeder Charles A. , Wener Kenneth R.
Published: October 2005

Much of the seafloor in the immediate vicinity of the Mississippi Delta consists of sedimentary material containing high concentrations of free gas. Specialized techniques were developed for direct measurement of the acoustic properties of these gas-charged sediments, to sub-bottom depths of the order of 300 ft (100 m). These techniques included seafloor receiving arrays, modified checkshot profiles conducted in conventional engineering borings, and a seafloor-penetrating, hydrophone-instrumented rod used in the study of the shallowest sub-bottom layers. Collection of corresponding sediment samples was carefully integrated with these seismic experiments, to better determine the geologic nature and mechanical properties of the gas-charged materials. Final data acquisition practice was influenced both by the unusual physical properties of the materials being investigated, and the presence of strong and rapidly changing currents from the Mississippi River. Results of these in situ measurements demonstrate the widespread occurrence of anomalously low acoustic velocities (less than 1000 ft/s, or 300 m/s) and related extreme attenuation of higher frequency energy (greater than 100 Hz).
Effects of sediment gas on chirp sonar reflection profiles
Authors: Schock Steven G. , LeBlanc Lester R. , Mayer Larry A.
Published: October 2005

Chirp sonar reflection profiles of gassy and gas-free seabeds are quantitatively compared to show the effects of sediment gas on normal incidence backscattering measurements. Acoustic FM pulses that sweep over the band of 2 to 10 kHz are generated by the chirp sonar and compressed using a correlation filter to generate a bandlimited impulse response of the seabed. The amplitude spectrum of the ideal wavelet (the unattenuated, compressed FM pulse) and the spectrum of wavelets backscattered from gassy sediments are used to investigate the frequency dependence of backscattering from gassy seabeds. [Work supported by ONR.]
Deep-towed acoustic measurements of gas hydrates
Authors: Rowe Mary M. , Gettrust Joseph F.
Published: October 2005

Acoustic data were collected using the Naval Oceanographic and Atmospheric Research Laboratory's (NOARL's) Deep Towed Acoustical/Geophysical System (DTAGS) at the northern end of the Blake Outer Ridge. A bottom-simulating reflector (BSR) is observed in these data at the same depth that it is found in surface-tow multichannel seismic sections from approximately 150 km to the east, near Deep Sea Drilling Project (DSDP) sites 102, 104, and 533. Analysis of the high-resolution (∼ 10 m) DTAGS data confirms that gas hydrate as well as unfrozen gas are concentrated within these sediments. Distinctive properties of the acoustic signal are combined with sediment sound speeds derived from these data to estimate the distribution and extent of the gas hydrate and regions of unfrozen gas. Results of analysis of DTAGS data extend findings from DSDP Leg 11, DSDP sites on the Middle America Trench, and the Black Sea. These data provide a means for determining mechanisms for the concentration of methane gas and the formation of gas hydrate. [Work supported by the Office of Naval Technology.]
Nonlinear acoustics
Authors: Beyer Robert T.
Published: October 2005

Nonlinear acoustics (NLA), within the framework of physical acoustics, has come of age over the past 30 years, yet new phenomena continue to be observed, so that the subject is not yet exhausted. The session will begin with a review of the mathematics of describing NLA (part 1). The analysis of one-dimensional phenomena will follow, plus the use of Burgers' equation (part 2). Data on the nonlinear parameter (B/A) will be reviewed (part 3). The physical aspects of nonlinear phenomena in two and three dimensions will be explored, and approximate methods of calculating the mutual effect of diffraction and nonlinearity will be described (part 4). The effects of the interaction of two sound beams will be considered (part 5). Applications will be treated. These include the development of parametric array sonar, surface wave devices, lithotripsy, and other medical applications (part 6). Such frontier topics as solitons and chaos will be touched on (part 7).
Auditorium acoustics: What should we measure? What do we measure and what does it mean
Authors: Vian J. P. , Pelorson X.
Published: October 2005

For many years the assessment of auditorium acoustics has been made through a set of acoustical criteria whose number and kind sometimes differ substantially between groups of specialists. The situation seems quite clear for speech auditoria as much as it is confused for music auditoria. Meanwhile a growing consensus has slowly come out about a small number of quantities that are considered to explain a large amount of the variability of subjective judgments, because they correlate individually with some subjective impressions. The acoustical quality of an auditorium should be allowed to be expressed univocally by the values taken by these criteria. Unfortunately several of these criteria are not independent and very little is known about the subjective significance of the various arrangements of criteria values. Moreover all the variability observed when measuring the criteria are related not only to physical features of the auditorium but also to a large extent to the measurement technique. Different measurement techniques are discussed and fluctuations among measurement procedures, among halls and within halls are compared. It is shown how difficult it is to make a conclusion on acoustical quality of a hall by looking only at the criteria. The need for a standardized method to take measurements is stressed, as well as the need for more research work focusing on criteria, making it possible to discriminate between halls when listening judgments are different.
High-power test of a barrel stave flextensional transducer
Authors: Moffett Mark B. , Clay William L.
Published: October 2005

Barrel stave flextensional transducers are potentially useful as compact, low-frequency, high-power projectors. An equivalent circuit model that includes a higher-mode, extensional compliance is used to estimate the maximum radiated power. Because the mechanical quality factor, Q, is low (on the order of 3 or 4), the source level of such a projector is limited by the maximum electric field that the piezoelectric ring stack driver can safely handle without depolarization or significant dielectric losses (about 400 kV/m for Navy type III lead zirconate titanate). A barrel stave flextensional projector 18 cm long and 9 cm in diameter with a mass of 4.1 kg in air was tested to 200 psig (1.4 MPa) in the pressure vessel at NUSC's Dodge Pond Field Station. A source level of 194.7 dB//1 μPa-m was obtained at 1.56 kHz for an applied rms voltage of 5 kV. The projector figure-of-merit was about 14 W/kg-kHz-Q, and this number would be expected to apply to a larger, lower-frequency projector of commensurate dimensions.
The generation of sound by a dipole moving near the edge of a half-plane
Authors: Schouten Gerrit
Published: October 2005

The shape and the spatial amplitude distribution of the sound pulse generated by the passage of a dipole (or ring vortex) near the sharp edge of a half-plane are computed and presented in plots. Instead of using a low-frequency approximation to the Green's function a direct approach to the potential of a moving dipole in a branched space is used together with an image dipole. In a compressible medium (with a finite velocity of sound) the wave is physically present. In the limit of an incompressible medium the wavelength becomes infinite and the wave degenerates into a time history of the pressure variation. The incompressible pressures agree with those obtained from direct differentiations of the classical results of Sommerfeld [Proc. London Math. Soc. 30, 121–163 (1897)]. The wave results are in conflict with some results presented in the literature [T. Kambe et al., J. Fluid Mech. 155, 77–103 (1985)] obtained with a low-frequency approach.
Wave propagation in a viscoelastic medium with a high concentration of pores
Authors: Ma Y. , Varadan V. K. , Varadan V. V. , Audoly C.
Published: October 2005

Wave propagation in a viscoelastic and porous medium, whose properties are temperature and frequency dependent, was investigated. The propagation characteristics of compressional waves in such a medium cannot be predicted using single scattering models when the porosity of the medium is considerable. Different from a previous study [Y. Ms, V. K. Varadan, and V. V. Varadan, ASME J. Heat Transfer 112, 402–407 (1990)], which was for electromagnetic waves, this investigation provided another proof of enhanced attenuation due to dependent scattering for the acoustic case. Most importantly, this is a problem of an elastic wave propagation in a lossy host medium with lossless scatterers which has seldom been considered. Numerical results of phase velocity as well as of attenuation of such a medium for different temperatures and different frequencies are presented. Differences in results between single and multiple scattering when the porosity is increased are also shown. Numerical results considering multiple scattering compare favorably with those from the experimental work which was done independently by G.E.R.D.S.M. in France. [Work supported by CEEAM.]
Computation of sound radiation from an arbitrary body with mixed boundary conditions using program CHIEF
Authors: Thompson W. , Siders C. M.
Published: October 2005

The computer program CHIEF has been modified to allow the computation of sound radiation from an arbitrary-shaped body where the normal velocity is prescribed on only part of the surface of the body while a locally reacting complex impedance is assumed to cover the remainder of the surface. This impedance can range in value from zero (pressure-release boundary condition) to essentially infinity (rigid boundary condition). Different values of impedance are allowable on different portions of the same surface. Some results of computations of far-field directivity patterns and the radiation impedance loading on simple-shaped radiators with the mixed boundary conditions are presented. [Work sponsored by ONT.]
The effect of onset rate on aircraft noise annoyance
Authors: Plotkin Kenneth J. , Bradley Kevin A. , Molino John A.
Published: October 2005

Noise from military aircraft operating at high speeds and low altitude can exhibit high onset rates, which are thought to increase the annoyance of these sounds. A set of listening experiments was undertaken to examine this effect and to evaluate the validity of an onset rate adjustment currently used in the environmental assessment of this type of noise. A basic set of 12 stereo sound recordings was prepared, consisting of four types of military aircraft with various onset rates plus one civil aircraft. These aircraft flyby sounds were presented at four sound levels to subjects in an indoor listening facility (nominal SEL of 95, 85, 75, and 65 dB) and at an outdoor facility (nominal SEL of 115, 105, 95, and 85 dB). Indoor sounds were filtered according to a typical residential noise reduction curve. Sounds were presented in random order, at random time intervals, and random approach from either in front of or behind the subjects. Subjects rated each sound on a seven-point annoyance scale. Two companion experiments were also performed at the outdoor facility. These experiments used modified military aircraft sounds with particular onset rates from 5 to 100 dB/s and decay rates from 2 to 30 dB/s. Analysis of the results of these experiments examined the effects of onset and decay rates, level, SEL, and duration. [Work sponsored by USAF AAMRL/BBE.]
An exploratory study of community noise levels in the city of Lima
Authors: Jiménez-Dianderas Carlos R. , Rivas-Tejeda Iván F.
Published: October 2005

Lima, the capital city of Perú, a metropolis with more than 6 million people, has in the last 30 years had a sudden, explosive, and unsettled growth. Consequently, the city is always attacked by an endless number of noise sources. The absence of requirements for acoustic planning has caused noise producing activities to be mixed in with buildings requiring a quiet sonic environment. This study analyzes the main community noise sources and their levels: traffic and transportation noise, aircraft, and industrial noise. The noise pollution levels obtained, which were calculated through theoretical formulas and empirical methods, are plotted in noise maps of the metropolitan area of Lima. Unfortunately, Perú does not have an acoustical research center, laboratories in acoustics, or professional researchers in acoustics. The results of this research allowed comparison of the average levels calculated, around 92 dB in the downtown area, in regard to requested noise levels. The lack of legislation, acoustic research, and people's knowledge about noise damage will lead to its progressive increase, almost 1 dB per year, in the near future.
Study of surface dynamics of drops in the presence of surfactants
Authors: Tian Yuren , Holt Glynn , Apfel Robert E.
Published: October 2005

The characteristics of capillary waves, especially energy dissipation, are strongly influenced by the presence of surfactants. The phenomenon has been studied by investigating experimentally the free quadrupole oscillations of a fluid drop acoustically levitated in the air. The experimental apparatus is similar to that of Trinh [Rev. Sci. Instrum. 56, 2059 (1985)], and the methods follow those reported by Lu and Apfel [J. Colloid Interface Sci. 134(1), 245 (1990)]. Using this system, the frequency of free quadrupole oscillations and its damping constant can be measured. Water drops with different sizes and different surfactant concentrations were used in the measurements. Experiment results show that the technique used here, which is nonperturbative and requires a very small amount of sample, may supplement other methods to measure the surface properties of liquid. [Work supported by NASA through JPL, Contract 958722.]
Stimulation of drop coalescence with acoustic cavitation
Authors: Gardner Edward A. , Apfel Robert E.
Published: October 2005

A standing acoustic field was used to levitate a pair of anisole (methoxybenzene) drops in an aqueous surfactant solution containing Teflon particles to act as cavitation nuclei. The drops were brought into contact with each other by the levitation field but did not coalesce immediately because of the surfactant in the water. By increasing the intensity of the sound field, cavitation events were produced, some of which ruptured the oil/water interface, causing plumes of micron-sized oil droplets to be expelled from one of the main drops. Occasionally, this disturbance caused the main drops to coalesce. This method of stimulating coalescence was studied using high-speed film and statistical analysis, which will be reviewed in the presentation. [Work supported by NASA through JPL, Contract 958722.]
Rectified diffusion during nonlinear gas bubble oscillations
Authors: Kamath Vinod , Prosperetti Andrea
Published: October 2005

Mass transfer of the dissolved gas across a bubble wall during nonlinear spherically symmetric oscillations is studied. Use of an earlier comprehensive model [Prosperetti et al., J. Acoust. Soc. Am. 83, 502–514 (1988)] to determine the bubble dynamics avoids the need to use ad hoc polytropic assumptions. A numerical technique based on a pseudospectral method is used to determine the dissolved gas concentration in the liquid. This formulation does not require the assumptions made in the classic theory of Eller and Flynn [J. Acoust. Soc. Am. 37, 493–503 (1965)]. In some conditions results indicate a significant difference in growth rate predictions when compared to the Eller-Flynn model. [Work supported by NSF.]
Nonlinear oscillations of gas bubbles in elastic solids
Authors: Massell Paul B. , Albin Gary
Published: October 2005

This work was part of a project whose long-range goal is the development of a device for estimating the size of bubbles in human tissue. Calibration standards are expected to consist of gas bubbles in polymer gels. Accordingly, equations in Prosperetti [J. Acoust. Soc. Am. 56, 878–885 (1974)] that describe forced oscillations of a gas bubble in a liquid have been modified to apply to the case of a gas bubble in a linearly elastic solid. The changes in the analytic expressions for the resonance solutions are modest, and the major features are preserved (e.g., hysteresis for main, subharmonic, and harmonic frequency regions). More precise equations for the liquid case in Kamath and Prosperetti [J. Acoust. Soc. Am. 85, 1538–1548 (1989)] have also been modified to treat the elastic solid case. Following these authors, a Galerkin spectral method was used to generate numerical solutions to the governing partial differential equations. Situations in which two or more stable solutions exist for a given set of parameters may be discussed.
Calculations of temperature within and without a pulsating gas-filled cavity
Authors: Church Charles C.
Published: October 2005

The temperature of the gas within a spherical cavity driven by a sinusoidal pressure field is calculated using an existing model [H. G. Flynn, J. Acoust. Soc. Am. 57, 1379–1396 (1975)] for cavitation dynamics. The temperature field in the liquid surrounding the bubble also is calculated with this model. For this work it is assumed that temperature variations are due to heat conduction only, although corrections for evaporation, condensation, etc., may be included if desired. Because the temperature T in the liquid at the cavity interface is allowed to vary (which reduces heat conduction by reducing the thermal gradient at the interface) the effect of holding T fixed is investigated. Results are presented for argon-filled and air-filled cavities in water or various organic liquids. [Work supported by ONR and NIH.]
Pressure transfer function from the diffuse field to the human infant ear canal
Authors: Keefe Douglas H. , Burns Edward M. , Bulen Jay C. , Campbell Shari L.
Published: October 2005

The diffuse field pressure transfer function H(f) to the ear canal of human infants was measured from 100–11 000 Hz. The diffuse field pressure and the ear canal pressure were simultaneously measured in a reverberant room using spatial averaging of source and microphones. The probe microphone tip was inserted 5 mm into the infant ear canal, and the parent was instructed to hold the infant while slowly walking around the room; an experimenter walked around the room with the other microphone. Results using KEMAR and in adult canals were consistent with the literature. H(f) for the 1-month-old infants has a strong peak (10–15 dB) at 4–5 kHz. The majority of the ten infants showed a twin peak structure, with the additional peak (8–12 dB) at 5–6 kHz, H(f) has a dip at 8–9 kHz and increases up to 11 kHz. A 5-dB peak at 1-2 kHz may be due to the proximity of the parent's torso to the infant's head. Additional results on older infants will be discussed. [Work supported by NIH.]
Frequency differences in the development of protection against NIHL by low-level “toughening” exposures
Authors: Subramaniam Malini , Henderson Donald , Spongr Vlasta
Published: October 2005

The aim of this study was to determine if low-level intermittent exposures to a 0.5-kHz OBN has a protective effect for future high-level exposures (1) at the same frequency or (2) at a higher frequency (4-kHz OBN). Four groups of monaural chinchillas were used as subjects. Thresholds were determined using evoked potentials recorded from a chronic electrode implanted in the inferior colliculus. In the first experiment, the experimental group was exposed to a low-level noise (an OBN centered at 0.5 kHz at 95 dB for 6 h/day for 10 days). After a 5-day recovery period when the thresholds returned to baseline, the animals were re-exposed to the same noise at 106 dB for 48 h. A control group was exposed only to the higher-level noise. The second experiment has an identical exposure schedule, except that the traumatic exposure involved a 4-kHz OBN presented at 100 dB. The 10-day “toughening” exposure reduced the amount of PTS in the low-frequency experimental group by 20–30 dB over the range of 0.5–4 kHz. Conversely, the amount of PTS in the high-frequency group was actually 15 to 25 higher than in the control group at and above the exposure frequency. The possible mechanisms involved will be discussed.
Finite element modeling of a radio ear bone vibrator
Authors: Hayek Emil R. , Pechersky Martin J. , Stuart Alan D.
Published: October 2005

The Radio Ear B-71 bone vibrator is an electro-mechanical transducer used in audiologic tests to diagnose hearing disorders. Extensive studies have revealed that the bone vibrator exhibits a peaked low-frequency response that limits its clinical usefulness. The vibration of this device has been previously characterized experimentally by optical holographic techniques. These results have indicated that the poor high-frequency response of the bone vibrator can be attributed to case resonances in the higher modes of vibration. To further investigate both the out-of-plane and in-plane vibration of the bone vibrator case, a finite element model was developed with the ANSYS system. The case mode shapes obtained previously by laser holography were used to verify the semiempirical FEM model. Once verified, this finite element model was used to analytically determine modifications to the bone vibrator that would improve its high-frequency response. This was accomplished by varying design specifications of the bone vibrator including its dimensions, stiffnesses, and masses and observing its effect on the case mode shapes.
Wave-number-frequency spectrum of turbulent wall pressure fluctuations
Authors: Karangelen Carolyn
Published: October 2005

The study of the properties of turbulent wall flows is important to understanding the structural excitations that might induce flow noise. Models of the forcing functions of the structural excitations have been based on generalized properties of the spectral features of these flows. This paper will highlight the characteristics of turbulent spectral energy in wave number space, and present new experimental results. Discussion will address the wave number spectrum as a model for the forcing function of structural excitation. [Funded by ONR and IBM.]
Prosodic categories and duration control
Authors: Beckman Mary E. , Edwards Jan
Published: October 2005

Two prosodic categories are particularly interesting for examining the relationship between phonetic units and articulatory timing because they provide a clear contrast in prosodic function: The durational correlates of “sentence stress” mark constituent peaks (nuclear-accented syllables), whereas phrase-final lengthening marks constituent edges. When kinematic patterns are contrasted in nuclear-accented versus unaccented and phrase-final versus nonfinal syllables, it seems that final lengthening is a local decrease in stiffness, whereas lengthening for accent is a change in the phasing of the final (consonant) gesture relative to the opening (vowel) gesture. When interaction with overall tempo is examined, however, it is clear that the prosodic function cannot be equated directly with the dynamic parameters, since at slow tempo, phrase-final lengthening affects phasing rather than stiffness. Thus prosodic structure is not the immediate goal of the dynamic representation. Rather, there must be intermediate representations of the phonetic tasks in terms of a local tempo change (for final lengthening) and an increase in the duration of the “sonority peak” of the syllable (for sentence stress). [Work supported by the NSF.]
On the analysis of speech movements
Authors: Westbury John R.
Published: October 2005

New technological developments have made it possible to compile, in one afternoon, a speech kinematic data set that once required 3 months of tedious, exhausting effort. In a week's time, sets that once required a year, and in a month, sets that once required several years, can be compiled. To those old enough to have done things in the old ways, this is surely remarkable, but perhaps also unsettling because there are few sound traditions to guide the analysis of this rapidly expanding articulatory database. Heretofore, a central feature of many analysis schemes has been a heavy reliance on identifying “magic” moments in time and places in space—easily defined “events” in the kinematic signal streams. Articulator positions and velocities associated with these events, and time and distance intervals between them, then provided a parsimonious characterization of the movements. This analytic approach is certainly useful, but also troubling, first because the functional significance of the measurement events is unknown; second, because their locations are sensitive to the essentially arbitrary conventions that must first be established to represent the data; and finally, because the few discrete measures that are made may under-represent the phenomena of interest, and lead to flawed generalizations. Examples will be provided to illustrate these weaknesses of the classical approach, and partial remedies will be suggested. It is high time that we talk about methods.
A multisectional representation of the tongue surface based on ultrasound scans for time-varying vocalizations
Authors: Cordaro Mare A. , Stone Maureen , Goldstein Moise H. , Unser Michael
Published: October 2005

This paper describes a technique for producing a movie of multiple planes of the tongue surface based on midsagittal and coronal ultrasound scans of the tongue during time-varying vocalizations. For each scan view, the ultrasound images and acoustic signal of a given vocalization are recorded on videotape. The resulting sequence of video fields is digitized and processed to yield a sequence of two-dimensional coronal tongue profiles. Formant and fundamental frequencies are determined from the acoustic signal segment corresponding to each video field. Data for a number of coronal scan views are recorded with the vocalization repeated for each view. The resulting tongue profile sequences are time warped in a piecewise linear fashion (utilizing characteristics of both the ultrasound and acoustic data) to produce a single sequence of multiple time-aligned tongue surface profiles that are displayed in slow motion or freeze-frame modes.
Toward the development of articulatory signatures for intelligibility test words: Lingual kinematics
Authors: Weismer Gary , Kent Ray D. , Turner Greg
Published: October 2005

The development of “normal” articulatory signatures for intelligibility test words should eventually permit highly specific designations of the articulatory basis of intelligibility deficits in persons with motor speech disorders. Our study of lingual kinematics for selected words, using x-ray microbeam data, suggests that a major obstacle to the construction of such signatures is the substantial interspeaker variability in pellet trajectories for a given word. This variability will be reported, ways in which it might be minimized will be discussed, and some analyses of relationships between lingual kinematics and vocalic formant trajectories will be described. One conclusion that has emerged from analyses to date is that typically used kinematic measurands such as peak velocity, instantaneous acceleration, and so forth, will not be very useful in the development of an articulatory signature. Rather, the unfolding of articulatory gestures over time must somehow be incorporated into the signature concept. [Work supported by NIH.]
Production of final consonant deletion in black dialect
Authors: Michou Gina , Hamlet Sandra , Jones Lewis
Published: October 2005

Deletion of certain final plosives is a phonological characteristic of American black dialect. This study reports physiological observations on the production mechanisms for such consonant deletion. Videofluoroscopic (x-ray) speech data were obtained for monodialectical speakers of black dialect, who were among subjects serving as normal controls in a study of head and neck cancer patients. Nonsense phrases of the form h ə CVC were spoken when cued by a precisely articulated live voice verbal model, uttered by a speaker of General American dialect. Some speakers of black dialect “omitted” the final plosives in this situation. Insights on production mechanisms affecting vowel transitions and glottalization of final consonants are reported based on tongue and hyoid bone activity in the final VC transition. [Work supported by NIH, Grant No. CA-43838.]
Determination of geoacoustic parameters of the ocean bottom—Data requirements
Authors: Rajan Subramaniam D.
Published: October 2005

An important problem in ocean acoustics is the determination of the acoustic parameters of the ocean bottom sediment layers. A variety of inverse methods has been proposed in the literature for obtaining these quantities from measurements of the acoustic field in the water column using either narrow-band sources. The ability of some of the perturbative methods to yield accurate estimates of the unknown parameters is investigated. For shallow water experiments, it is shown that a full wave method that uses the complex pressure field as data is nonlinear, the nonlinearity increasing with frequency and waveguide thickness. Methods that use modal eigenvalues as input data are only weakly nonlinear and can successfully yield estimates with acceptable resolution if the experiment is performed over a number of frequencies. In the case of deep water experiments, however, the experimental configuration can be so arranged as to make methods based on full wave inversion only weakly nonlinear.
Time domain inversion of two-dimensional velocity fields using simulated annealing
Authors: Gerstoft P. , Pedersen J. M. , Vestergaard P. D.
Published: October 2005

Inversion of scattered sound fields caused by horizontal and lateral velocity variations can be done using an efficient Monte Carlo method called simulated annealing. The subsurface contains large velocity variations in both depth and range and thus, for inversion of transient signals, at least a two-dimensional (2-D) representation of the velocity field is required. This 2-D description requires that the nonlinear inversion is carried out in a huge parameter space. Standard local optimization methods will be trapped in local minima and a search throughout is computationally prohibitive. Thus the simulated annealing method is used. The present implementation is here based on an ensemble approach whereby several copies are annealed simultaneously. By using several copies it is possible to obtain statistical information about the optimal cooling rate. In order to make the method converge in acceptable time, both optimization and the forward modeling method of the inversion have to be fast. Thus geometrically flexible but computationally exhaustive methods such as finite difference are not yet used. At present, the forward modeling is done by either the one-dimensional convolution model or ray tracing. The 2-D effect of the one-dimensional convolution is obtained by geometrically requiring the structure to be stratified with a weak variation in range. For the ray tracing, the substructure shall also be stratified but here the wave propagation is in a real 2-D environment.
Linearization of the matched-field processing approach to acoustic tomography
Authors: Tolstoy A.
Published: October 2005

This paper continues the approach presented in Tolstoy et al. [J. Acoust. Soc. Am. 89, 1119–1127 (1991)] but offers a much improved inversion technique, i.e., a linearization of the problem, which reformats the computations in terms of simple nonsquare matrix inversion for an overdetermined system. This linearization results in sound-speed accuracies that are an order of magnitude better than the earlier technique. In addition, calculations confirm that for simulations with white, Gaussian, uncorrelated noise, the linear/Bartlett processor results are identical to those of the minimum-variance/Capon processor. Finally, optimal source-receiver configurations have been determined by exhaustively computing the condition numbers for the associated matrices in the new linear formulation. Simulation results now show that three arrays located at optimal coordinates in a 250- by 250-km ocean region with shot sources distributed around the perimeter can result in 3-D sound-speed profiles determined to accuracies better than 0.07 m/s and better than 0.03 m/s for four arrays located at optimal coordinates. Such results presently assume perfect knowledge of sound-speed profiles at the arrays and around the region perimeter.
Room acoustic parameters with SLM and computer
Authors: Hansen Kjeld T.
Published: October 2005

The Schroeder method, also called the integrated impulse-response method, is implemented using application module BE 7109 with an SLM (modular precision sound level meter B&K type 2231). A noise burst is generated by the SLM and fed into an amplifier and loudspeaker. The room response is then sampled and the reverberation times EDT, T(20), and T(30) are calculated automatically for 1/1-octave or 1/3-octave bands. The system gives very reproducible and accurate results which can be displayed. By connecting the SLM to a computer running the application program ROOMAC, which is part of BX 7109, the decay curves can be transferred to the computer. From these curves the more sophisticated parameters clarity, deutlichkeit, centre time, and total sound level can be calculated. These are displayed together with the sampled decay curves, the integrated curves, and the reverberation times after each frequency measurement thus giving the user immediate feedback. The results can be stored on disk. Furthermore, up to 12 positions can be spatially averaged. Altogether this makes the system especially valuable where a portable system and in situ calculation and diagnosis are needed. Measurement of the platform parameter SUPPORT will be discussed.
Measurement of spatial information in auditorium by four closely located microphones
Authors: Yamasaki Yoshio
Published: October 2005

Quite different impressions are felt in sound fields that have about the same reverberation time and sound pressure level. This kind of difference might come from the difference of spatial information, so it is important to grasp the spatial information in sound fields, especially of the early reflection periods. In this presentation, a way to grasp the spatial information of sound fields from impulse responses measured at four closely located points; the origin and three points of the same distance, 5 cm from the origin on the rectangular coordinate axes, is discussed. From these four impulse responses, the coordinates and powers of virtual image sources are calculated by correlation or intensity technique. Concert halls, opera theaters, and many other sound fields are measured by this technique. This measurement has been introduced not only to actual sound fields, but also to scale models. The distributions of virtual image sources and directivity patterns of auditoria and scale models are shown. These data bases are being used to estimate the sound fields and feed them back to acoustic design of auditoria.
Measurements of the impedance presented to the string by a bow
Authors: Ricca Bernard , Weinreich Gabriel
Published: October 2005

It is well known that the various parameters involved in bowing a stringed instrument (e.g.. bow “pressure”) are important in determining the wave shape and stability of the vibrating string (and hence the sound produced by the instrument). A fuller understanding of this process, however, requires knowledge of the force characteristic of the bow on the string. The motion of a string vibrating both freely and while interacting with a bow have been measured and from these measurements the impedance presented by the bow to the string was determined. The method for measuring string motion is based on earlier work [B. Ricca, G. Weinreich, and N. R. Michael, J. Acoust. Soc. Am. Suppl. 1 86, S15 (1988)]. By it, the impedance presented by the bow to the string both parallel and perpendicular to the bow hair is determined. Some results will be presented. [Work supported by NSF.]
Numerical and physical experiments on hammer and piano strings
Authors: Chaigne Antoine , Askenfelt Anders , Jansson Erik V.
Published: October 2005

Numerical experiments have been made on the piano string with a discrete model using a finite difference calculation procedure. The string model was previously applied to the guitar [A. Chaigne, J. Acoust. Soc. Am. Suppl. 1 88, S188 (1990)] and is now tested with experimentally obtained data for the piano. The numerical experiments include systematic variations of parameters such as hammer velocity and nonlinearity of the felt hammer and their influence on generated waveforms and spectra. Earlier physical experiments on pianos have provided data on the velocity of the hammer and the string. In addition, the hammerstring interaction force has been estimated by measuring the compression of the hammer felt during string contact. Recorded string tones and measured waveforms will be presented and compared with typical examples of those calculated.
Tuning of the Tongan nose flute fangufangu
Authors: Hoekje Peter L.
Published: October 2005

The fangufangu is made from a cylindrical section of bamboo closed by two adjacent nodes. Bore radii (a) range from 1.5 to 5 cm and lengths (L) from 20 to 60 cm. Typically, six identical holes are burned through the side walls: one at either end, two in the center, and two symmetrically placed near (L/4) from the ends. Hole radii (b) range from 0.5 to 0.9 cm. One end hole is blown through a slit between the bamboo wall and the player's nostril. The four traditional fingerings use the next hole and the farthest hole. All have two resonances within the lowest octave, but one mode does not sound and two are only about 50 cents apart. There are thus six playable notes in this range, but scale tunings vary widely among existing instruments. Multiple mode cooperations are rare. For a given value of (a), increasing (b/a) overall raises frequencies of most resonances in parallel, but one frequency rises faster than the trend and another falls. They cross when (b/a) = 0.2 (a = 1.6 cm, L = 48 cm). Individual hole sizes and positions can be perturbed for specific tuning effects, as shown by calculation and experiment.
Industrial audiometry: Benefit or liability
Authors: Suter Alice H.
Published: October 2005

In the U.S., audiometry is usually considered an essential component of a hearing conservation program and it is widely used to identify workers whose hearing threshold levels have begun to deteriorate so that interventions can take place. Reliance upon audiometry may not always be warranted, however, especially when employers are tempted to skimp on their engineering noise control programs. There is a strong voice against requiring industrial audiometry among heating professionals in Canada and Australia. These experts claim that the reliability and validity of industrial audiometry tends to be poor, that workers are often falsely reassured that management is taking proper care of their hearing, and that workers tights are being abridged by mandatory audiometric testing. Although these arguments are not always supported by this author, they are potentially important and worthy of exploration.
Motivational benefits of audiometric monitoring
Authors: Glaser Rena H.
Published: October 2005

Audiologists and other professionals who administer occupational hearing conservation programs have for years used audiometric test results to determine the effectiveness of their programs and to show management any departments or areas that require attention. One aspect of the value of audiometry in industry that has received minimal attention is the educational and motivational impact that audiometric test results may have on the employee. Ideally, the test results should be given to the employee immediately following the test. This gives the employee the opportunity to ask questions and allows the examiner to praise the employee's good hearing conservation practices if no significant changes are noted in the employee's audiogram. If hearing thresholds have decreased, the tester is given the opportunity to reinforce the need for hearing protection use both on and off the job. All employees who receive audiograms should receive a meaningful summary of their test results. If this summary cannot be done immediately following the audiogram, written feedback is imperative. Employees are more willing to cooperate with management in these programs when employees can ascertain a benefit to themselves.