bluuebunny/crossref_metadata_2025 huggingface dataset:
A wearable multichannel vibrotactile aid for the deaf
Authors: Engebretson A. Maynard , Gong Fengmin , O'Connell Michael P.
Published: October 2005

It has been determined that hearing-impaired and normal-hearing subjects can learn to identify words using only a tactile vocoder [Brooks and Frost, J. Acoust. Soc. Am. 74, 34–39 (1983)]. Further studies have shown that certain multichannel tactile vocoders provide significant help in understanding connected discourse as an aid in lipreading [Weisenberger and Miller, J. Acoust. Soc. Am. 82, 906–916 (1987)]. A review of this research is given in a companion paper (Weisenberger, Abstract J1). Motivated by these results, a wearable, 16-channel vibrotactile aid has been developed that can be used by hearing-impaired subjects during normal daily activities. The system consists of a body-worn processor that is 3.5 × 5.5 × 1.5 in. in size and a vibrator array worn on the arm. In addition to the 16-channel vocoder algorithm, the microprocessor-based system can be programmed to implement other processing algorithms using the existing hardware. The system and its performance characteristics will be described. [Work supported in part by NIH.]
Tactile reception of fingerspelling and sign language
Authors: Reed C. M. , Delhorne L. A. , Durlach N. I.
Published: October 2005

Previous work on tactile speech reception by deaf-blind individuals has focused on the Tadoma method [Reed et al., J. Acoust. Soc. Am. 77, 247–257 (1985)]. Two additional methods of tactile communication, both of which are adaptations of methods designed for the visual sense but are used extensively within the deaf-blind community, are tactile fingerspelling and tactile signing. The goal of the current research was to document the communication abilities of highly experienced deaf-blind users of tactile fingerspelling and tactile signing. Experiments were conducted to determine reception accuracy for sentence-level materials as a function of rate of presentation for each of the two methods. The results of these experiments will be compared to those obtained for visual reception of fingerspelling and signing as well as to results obtained through the Tadoma method of tactile speech communication. [Work supported by NIH.]
Absolute magnitude estimation of loudness by adults and children
Authors: Gescheider George A. , Collins Amy A.
Published: October 2005

Twenty-three subjects performed absolute magnitude estimation of the lengths of a series of lines and the loudness of a series of tones as well as cross-modality matching between loudness and perceived line length. The results support the hypothesis that subjects judge stimuli on an absolute scale. Specifically, for 9 out of 12 adults and 9 out of 11 children, lines and tones assigned the same number in magnitude estimation were judged to be subjectively equal in cross-modality matching. A correction procedure was employed to eliminate the effects of idiosyncratic number usage from the magnitude estimations of loudness. This correction procedure, consisting of dividing the loudness exponent by the line length exponent, produced power function exponents for loudness that were virtually identical for magnitude estimation and cross-modality matching. Implications of the results for clinical measurement of loudness are discussed.
Psychometric functions for level discrimination
Authors: Buus Søren , Mason Christine R. , Florentine Mary
Published: October 2005

To determine the form of psychometric functions for 2I, 2AFC level discrimination, ten increment levels were presented in random order within blocks of 100 trials. Stimuli were chosen to encompass a wide range of conditions and difference limens: eight 10-ms tones had frequencies of 0.25, 1,8, or 14 kHz and levels of 30, 60, or 90 dB SPL; two 500-ms stimuli also were tested: a 1-kHz tone at 90 dB SPL and a white noise at 63 dB SPL. For each condition, at least 20 blocks were presented in mixed order. Results for three normal listeners show that the sensitivity d′ is nearly proportional to ΔL{= 20 log[(p + Δp)/p], where p is pressure} over the entire range of difference limens. When d′ is plotted against Weber fractions for pressure Δp/p or intensity ΔI/I exponents of the best-fitting power functions decrease with increasing difference limens and are less than one for large difference limens. These results indicate that the transformation from stimulus intensity to decision variable may be approximately logarithmic and that ΔL—plotted on a logarithmic scale—is an appropriate representation of level discrimination performance. [Work supported by NIH.]
Auditory fatigue and induced loudness adaptation
Authors: Charron S. , Botte M. C. , Mönikheim S. , Schaff B.
Published: October 2005

Measurements of induced loudness adaptation and temporary threshold shift (TTS) were made on 48 young subjects. Loudness adapatation of a continuous 60-dB test tone was induced in the right ear by an intermittent 1000-Hz inducer tone at 90 dB, presented every 30 s for 20 s. The loudness of a 1000-Hz or 1160-Hz test tone at 60 dB was measured after each occurrence of the inducer by the method of successive magnitude estimations. Induced adaptation caused the loudness of the continuous tone to decrease on the average by 38% (the equivalent of 14 dB) after 120 s. In a separate session, the subject's right ear was exposed for 45 min to a 1000-Hz tone at 90 dB SPL. One minute after exposure, thresholds were measured by Békésy tracking for 4 min. The maximum TTS, averaged across subjects, was 20.4 dB at a mean frequency of 1635 Hz. The correlation between maximum TTS and the amount of induced adaptation was 0.83. Thus ipsilaterally induced adaptation (IIA), which is akin to temporary loudness shift, may stem from cochlear mechanisms just as TTS does. Also, IIA could become the basis for an audiological test to identify those individuals most susceptible to auditory fatigue. [Work supported by Ministère de l'Environnement and NIH.]
Reduction of auditory damage due to intermittence
Authors: Ward W. Dixon
Published: October 2005

Two groups of chinchillas were given daily exposures, 5 days/week for 9 weeks, to 700–2800-Hz noise at 110 dB SPL. Each day, one group received a single 48-min exposure, the other group a series of 40 1.2-min bursts spaced at 12-min intervals. Whereas the continuous single exposures produced a median permanent threshold shift (PTS) of 16 dB at 1, 2, and 4 kHz and destruction of 33% of the outer hair cells (OHCs), the intermittent exposures resulted in a PTS of only 6 dB and less than 5% destroyed OHCs. Inasmuch as the latter group suffered about the same cochlear damage as (and less PTS than) a group given 45 daily 48-min exposures at 102 dB SPL, one can infer that an 8-dB “correction for intermittence” of a 110-dB exposure is approximately correct, in accordance with present OSHA regulations governing industrial noise exposure. [Research supported by NIH Grant 12125.]
Design of an experiment to measure the acoustic mutual impedances of a resonant, close-packed sonar array
Authors: Thompson Stephen C.
Published: October 2005

Knowledge of the acoustic mutual impedance coefficients for a sonar array is necessary to achieve an accurate analytical description of the performance of the array. In the early stages of a design, analytical approximations, e.g., of an array in an infinite rigid plane baffle, provide adequate estimates. When prototype hardware is available, it may be appropriate to derive refined estimates of the impedance coefficients. This allows more accurate prediction of the effects of design changes on performance, and also provides an analytical baseline for a design that is entering production. The measurement of the mutual impedance coefficients in a resonant, close-packed array is difficult. The only previously reported attempt [Stephen C. Thompson, J. Acoust. Soc. Am. Suppl. 1 68, S34 (1980] achieved inconclusive results, due to inaccurate estimates of the element electromechanical transfer matrices and strong element interactions that occur in the vicinity of the element resonance frequency. These measurements are being repeated, with greater care given to the previously noted deficiencies. The experiment will be described, concluding with the requirements placed on the special transducer elements that were necessary for the measurement. The design of these transducer elements will be described in a companion paper in this session [M. P. Johnson, J. Acoust. Soc. Am. Suppl. 1 82, S2 (1987)].
Observation of thermal ice-cracking in the Arctic Basin
Authors: Zakarauskas P.
Published: October 2005

It is now well known that thermal ice-cracking is a major contributor to under-ice ambient noise in certain regions of shore-fast ice during winter and spring [A. R. Milne, J. Geophys. Res. 77, 2177–2192 (1972)]. A report is given here of an observation of thermal ice cracking made by the Defense Research Establishment Pacific over polar pack ice during the spring of 1987. The number of events, as counted by a time-domain kurtosis method, is showed to follow the temperature changes of the air very closely. Thermal ice-cracking was the dominant ambient noise source during the periods of rapid air cooling. For thermal ice-cracking to occur, three conditions must be met: low temperature, low ice salinity, and little or no snow cover. Since the only ice surfaces directly exposed to air in the vicinity of the experiment were the vertical sides of large blocks of ice in pressure ridges, it is hypothesized that the cracks could have originated there.
Attenuation of sound through laboratory grown saline ice
Authors: Jezek K. C. , Stanton T. K. , Gow A. J.
Published: October 2005

Attenuation of acoustic waves transmitted through saline ice was studied in situ as ice formed in a large, outdoor pool. Amplitude of sonar pings (50–800 kHz) transmitted normal to the ice sheet surface were measured after passing through ice about 18 cm thick and having an average salinity of about 4 parts per thousand. Columnar crystals in the body of the ice sheet and a fine, dendritic structure near the base of the ice sheet (dendrites were about 0.5 mm thick) characterize the ice as being nearly identical to young, undeformed sea ice found naturally covering the polar oceans. Additional measurements were performed on newly grown saline ice about 3 cm thick. Measured attenuations through the 18-cm-thick ice ranged from about 20 dB at 50 kHz to 80 dB at 420 kHz. For the 3-cm-thick ice, total attenuation at 188 kHz was about 12 dB (compared to about 40 dB for the 18-cm-thick ice). That this represents an absorption of the acoustic wave by the ice is evidenced by two other observations: first, a low reflection coefficient measured on newly grown ice (about 0.04 at 188 kHz); second, measurements of scattered energy back into the transmitting region showed little redistribution of energy into nonspecular directions. Based on the observed decrease of attenuation per unit thickness of ice, significant absorption is attributed to the lower, porous and permeable portions of the ice. Presumably the important absorption mechanisms are associated with the pure ice dendrites and alternating planes of brine pockets.
The impact of Playhouse Square on the resurgence of Cleveland
Authors: Wilker Lawrence
Published: October 2005

Cleveland, Ohio, was a city in economic distress when a group of farsighted citizens and local officials decided to develop a downtown cultural center. Lacking the funds for a 300 million dollar project, it was decided to renovate a three-room vaudeville/film theátre complex, known as Playhouse Square. One theatre was designated as a drama/dance/chamber orchestra facility, another as the home of the Cleveland Opera and Ballet Companies, and the third as a venue for popular entertainment. The paper traces the history of the project and its impact on the resurgence of Cleveland.
Accelerometer array as a means to evaluate structural underwater sound
Authors: Brenot D.
Published: October 2005

The turbulent boundary layer low-wavenumber component, an important source of underwater structure encitation, cannot be precisely determined. Nevertheless, the resulting wall accelerations can be accurately measured. They already contain the coupling with the fluid, avoid the computation of the structural motion, and allow direct calculation of the farfield noise radiated by the vibration itself: The single frequency farfield noise radiated in a given direction by a baffled panel comes from one component of the wavenumber acceleration spectrum, and only one (see M. C. Junger and M. Pérulli, Elements d'Acoustique Physique, p. 59). This component may be obtained experimentally by performing the Fourier transform of the wall acceleration using an accelerometer array. An underwater experiment is shown on a 3-mm-thick panel with a 5 × 5 accelerometer array matrix (Δx = 70 mm. Δy = 60 mm) and on a thick cylinder (radius: 1 m; length: 12 m) with a 10-accelerator linear array. The parabolic laws between wavenumber and frequency clearly appear and are quite typical of each element. These measures can thus be used to estimate their radiation efficiency. [Work supported by DCN/CERDAN.]
The importance of context on the realization of phonemes
Authors: Chen Francine R.
Published: October 2005

Linguists and speech researchers have formulated many rules describing the variability in the phonetic realization of spoken words. Using a data base of spoken sentences that has been phonetically transcribed (Lamel et al., “Speech database development: Design and analysis of the acoustic-phonetic corpus,” DARPA Speech Recognition Workshop, 1986), some of these rules are quantified by examining, the effect of different phonemic environments on the phonetic realization of spoken words relative to a canonical dictionary representation. Modifications are analyzed in terms of the general categories of insertion, deletion, substitution, or match, and in detail in terms of each type of modification. The different contexts are studied along many dimensions, including stress, foot position, part of syllable, and word-initial/word-final position. Representations for compactly describing the environmental contexts are also developed. Preliminary results suggest that the importance of each of the dimensions that can be used to specify a phoneme's context is phoneme-dependent. Additionally, the strength of the relationship between observed modifications and contexts vary across dimensions for each phoneme. [Work supported in part by DARPA.]
An integrated approach to automatic detection of retroflexed and high-fronted approximants in continuous speech
Authors: Gengel Roy , Hieronymus James
Published: October 2005

Our goal is the development of speaker-independent, semivowel detector classifiers for use with continuous speech [R. W. Gengel and J. L. Hieronymus, J. Acoust. Soc. Am. Suppl. 1 80, S19 (1986)]. Progress on detection of retroflexed approximants (/r/,/ɝ/,/ɚ/) in one branch of a classification tree, and high-fronted approximants (/y/,/i/) and high-front vowels (/ɪ/,/eɪ/,/ɛ/) in another, is reported. The analytical scheme relies heavily on energy ratios selected on the basis of “frames of reference.” For example, a basic frame of reference is the energy in the frequency band between approximately 2–3 kHz. According to formant theory, the energy level in this band should be relatively low for retroflexed approximants (F1-F3 below 2 kHz) and relatively high for high-fronted approximants (F2,F3 above 2 kHz for) male speakers. In contrast, the energy band between about 1.2–2 kHz should be relatively high for retroflexed approximants while the band between about 0.6–1.6 kHz should be low for high-fronted approximants. By using “energy 2000–3000” as part of the denominator for a retroflexion detector and as a part of the numerator for a high-fronting detector, energy ratios are developed. The quotients of these ratios are then used in two-dimensional cluster analyses. Other ratios are used in subsequent cluster analyses. Results so far indicate that greater than 90% of target tokens can be correctly detected in a corpus of several hundred read sentences. Ratios of correct detections/incorrect detections vary between approximately 1.0/0.63–1.0/2.50. Some pros and cons of the method will be presented. [Work supported in part by DARPA Contract N0003984PD41304.]
A review of adaptive microphone arrays
Authors: Sondhi M. M.
Published: October 2005

In this talk, several algorithms for adaptive optimization of broadband microphone arrays will be described. The arrays may be linear, two-dimensional, or three-dimensional. Each microphone in the array feeds a tapped delay line filter, and the outputs of the filters are summed to give the final output. The problem to be discussed is that of adaptively adjusting the tap weights of the filters in order to optimally receive a desired speech signal in the presence of broadband noise sources with unknown locations and possibly slowly varying characteristics.
Three-dimensional microphone arrays
Authors: Flanagan J. L.
Published: October 2005

Low-cost, high-quality microphones and integrated electronics prompt examination of sophisticated arrays for sound pick-up in large enclosures. A three-dimensional, uniform configuration of receivers is studied and shown to have several benefits. Beamforming and delay steering can be accomplished over the 4π solid angle without spatial ambiguity. Beamwidth is essentially independent of steering direction. As in arrays of fewer dimensions, usable bandwidth is governed at the upper frequency limit by receiver spacing and at the lower frequency limit by linear dimensions. Harmonic nesting in three dimensions can extend the bandwidth of unique spatial discrimination to any desired range. Range selectivity, additional to unique directional discrimination, can be realized by delay steering to nonplanar wave fronts.
Illusory continuity of periodic sounds: A comparisan of tonal and infratonal temporal induction
Authors: Warren Richard M. , Wrightson John M. , Puretz Julian
Published: October 2005

Tones may appear to remain on continuously when alternated with sounds having appropriate spectral composition and intensity. The limiting conditions for this illusory continuity have been used to define the characteristics of neural spectral (place) analysis of tones. The present study extends investigation of the apparent continuity of interrupted complex periodic sounds to infratonal frequencies, exploring the range of repetition frequencies from 10–2000 Hz. Evidence is presented indicating that reconstruction of obliterated segments of periodic sounds need not be based upon the neural place mechanisms associated with perception of tones. It appears that illusory continuity of periodicity can involve a perceptual synthesis based upon neural temporal information, and that explanations for the limits of illusory continuity of tones (“pulsation thresholds”) solely in terms of a frequency domain analysis involving neural place information may be incomplete. [Work supported by AFOSR.]
The effect of signal-frequency uncertainty in a CMR paradigm
Authors: Grose John H. , Hall Joseph W.
Published: October 2005

The phenomenon of comodulation masking release (CMR) indicates that the auditory system is capable of comparing the outputs of several auditory channels simultaneously. The presence of the signal is presumed to be cued by a dissimilarity in the temporal pattern in that channel, relative to the remaining comodulating channels, due to the addition of the signal. In its simplest form, such a cuing mechanism could operate quite independently of any a priori knowledge of which channel the signal occurs in. To test this possibility, a study was undertaken to compare the effect of signal-frequency uncertainty in a comodulated and a noncomodulated background. It was hypothesized that the detection of a signal whose frequency fluctuated randomly from trial to trial would be less deleteriously affected in a comodulating background than in a noncomodulating background. A novel feature of this study was the use of amplitude-modulated pure-tone components as the background masker. Results to date indicate that the effect of signal-frequency uncertainty is itself small relative to fixed-frequency signals, and no significant difference has emerged between its measurement in comodulated versus uncomodulated backgrounds.
Three-dimensional oceanographic acoustic modeling of complex environments
Authors: Kuperman W. A. , Porter Michael B. , Perkins John S.
Published: October 2005

Remote sensing combined with oceanographic modeling opens up new possibilities for quantiatively describing very large area complex oceanographic-acoustic phenomena. A complex ocean environment consists of variable oceanography including mesoscale phenomena and variable topography such as continental slopes and seamounts. Predicting the acoustical effects from any to all of these phenomena is a computationally intense problem whose efficient and accurate solution will, no doubt, ultimately employ new and innovative numerical physics. As a stimulus to developing new approaches, three-dimensional modeling results for such complex environments are being looked at using a technique that can rapidly calculate propagation loss over a wide geographical area. This approximate technique, which is based on normal mode theory, has been applied to environments that contain both variable oceanography and topography. Of prime interest in these initial studies is a search for graphical patterns that emerge for complex environments where the acoustical results reflect or “image” the oceanography and topography. It is believed that these three-dimensional representations using color graphics to display and convey complex ocean-acoustic phenomena will provide the impetus to further understanding and computing the interaction of these phenomena.
The PE method and the ocean tomography
Authors: Shang E. C.
Published: October 2005

It was well known that both the ray method and the PE method can handle wave propagation problems in 3-D environments, but both of them are approximations of the wave equation. In ray method, the diffraction term was discarded so it is good for high frequency; in PE method, the term of second-order derivation on range was discarded so it is good for narrow angle. The accumulated phase error restricts the range within which each method is valid. One has to choose a better method to adapt a specific situation. In part (1) of this paper, the case of individual mode propagation in SOFAR channel is investigated by analyzing the different valid ranges. In part (2), the effects of a mesoscale ocean eddy on mode propagation by using PE (IFD) code are discussed. The main goal is to find out if the mode coupling matrix is sensitive enough to apply in the “matched-field” method for the purpose of ocean tomography [Work supported by NRC.]
Three-dimensional underwater acoustic propagation through a steady shear flow
Authors: Robertson J. S. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

Previous studies by the authors have incorporated current effects into parabolic approximations, when the current vector lay within the vertical source-receiver plane. Here, the current and the source-receiver plane are not constrained to be parallel, and thus a solution to a fully three-dimensional problem is obtained. A class of sound-speed profiles is examined that is advected in a steady, depth-dependent ocean current. A cw source is submerged between a horizontal pressure-release surface and a horizontal bottom. When certain asymptotic order conditions on derivatives of the current and sound speed are satisfied, parabolic approximations of canonical form result. Furthermore, if additional restrictions on azimuthal derivatives apply, the azimuthal modes are decoupled so that the azimuthal angle appears only as a parameter in the parabolic equations. Thus the pressure field may be calculated in decoupled vertical planes, i.e., in an N × 2-D approximation. Several examples are discussed, and the acoustical effects of current structure are illustrated, with emphasis on azimuthal dependence of relative intensity. [Work supported by ONR.]
Effect of fluidal-structural coupling on the acoustical decays in a reverberation room in high-frequency range
Authors: Jie Pan , Bies D. A.
Published: October 2005

The effect of the coupling between a sound field and test panels upon their decay behavior is investigated in high-frequency range. Quasitransient solutions of the average energies in the room and the panels are used to estimate the reverberation times in the room and to calculate the decay curves of a test panel. Experiments are conducted to verify these solutions. The estimated and measured results are in good agreement in high-frequency range, which indicates that the average decay behavior of the room and panels can be analyzed in terms of the average modal parameters. The amalgamation of the average modal parameters (of the test panels and the reverberation room) can be related to the Sabine absorption coefficient αSab of the panels. This result provides a possible interpretation for the αSab of a modally reactive surface and suggests a way to estimate this quantity by statistical energy analysis (SEA) method. The dependence of the αSab upon the room properties, in which the panel is measured, is demonstrated both experimentally and analytically.
An indirect boundary integral equation method for architectural acoustics
Authors: Holger D. K.
Published: October 2005

A numerical method and the resulting computer program for prediction of interior acoustic fields are described. The method is based upon an indirect boundary integral equation formulation of the Helmholtz equation using hybrid layer potentials. The computer program incorporates general boundary conditions directly, and utilizes piecewise constant variable approximations. It is capable of predicting the steady-state response of enclosures with finite impedance boundaries, vibrating boundaries, and multiple interior sources. Numerical results are presented for the acoustic field inside a rectangular prism under various boundary conditions and with various excitations. Apparent limitations of the current program are discussed, and various potential applications in architectural acoustics and noise control are suggested. [Work performed at the Institutt for Teleteknikk, Norges Tekniske Hogskole, Trondheim, Norway and supported by NTNF.]
Acoustical considerations in design of semienclosed small arms training facility
Authors: Sachs Felix , Lewis Nelson , Luz George
Published: October 2005

Semienclosed small arms training ranges combine bullet trap features of an indoor range with the ventilation of outdoor ranges. Acoustic reverberation of indoor ranges and directivity effects of outdoor ranges are also combined in the semienclosed range. When designers of a semienclosed range failed to design for the acoustic directivity of guns, community noise levels increased and residents who had adapted to a long-standing noise environment from an outdoor range began complaining. Personnel on the firing line also noticed an increase. Measurements at the firing line demonstrated a sevenfold increase in the occupational noise dose, while measurements made out to 500 m demonstrated an 8-dB increase in the community noise exposure. The 8-dB increase was attributed to the reflection of the forward weapon report from the bullet trap baffles. The increase in noise exposure at the firing line was attributed to reverberation from the side walls and roof of the semienclosed range. The measures to reduce both the occupational and community exposures are addressed.
Acoustical design for the Merkin Concert Hall and the Hebrew Arts School
Authors: George Peter J.
Published: October 2005

Sound control issues were critical in the design of the multistory building that required relatively light-weight construction. The Anne Goodman Recital Hall was located directly above the Merkin Concert Hall. Dance studios were adjacent to Piano Classrooms, which were adjacent to Practice Rooms. Comparison is made between the techniques used on this building and those for the neighboring Juilliard School.
Acoustical design for the Tisch School of the Arts
Authors: George Peter J.
Published: October 2005

New York University's Tisch School of the Arts has moved into a 12-story building that was gutted and recycled to provide a new home for the School. In addition to classrooms, the building includes screening rooms, edit rooms, a recording studio, an AM/FM radio station, two television studios, and a sound stage. The design approach is described and the completed results are analyzed.
Controlling the shape of an acoustic spectrum automatically in various spaces
Authors: Carlsen Thor , Peppin Richard J.
Published: October 2005

Often, when a room is excited by a specified spectrum, the resulting spectrum differs in shape from that desired. Caused by the impedance of the space and by the objects within, in the past, the change has been accounted for by the use of a spectrum shaper before the noise generator, which was manually adjusted so that the desired shape and level of the output was achieved. This paper presents a discussion of a bus-controlled spectrum shaper that, in conjunction with a computer controlled realtime analyzer, allows the shape of the desired spectrum to be achieved without operator intervention. Uses for vibration excitation will also be discussed.
The Federal Emergency Management Agency's alert and notification systems review program
Authors: Wingo Craig S.
Published: October 2005

Nuclear power plants throughout the United States are required by the Nuclear Regulatory Commission (NRC) to provide the means for early notification and clear instruction of the populace within the 10-mile radius Emergency Planning Zone (EPZ) around each plant. The regulations and the Federal Emergency Management Agency's (FEMA) technical program for reviewing and approving alert and notification systems are discussed in this paper. The FEMA program consists of an acoustical/engineering review of the system design, coupled with a telephone survey of residents of the EPZ following activation of the system to determine its effectiveness. To date, system designs have been submitted for every nuclear power plant in the nation. The engineering design review has been completed at 68 sites, and a telephone survey has been completed at 63 sites. Recently, the technical standards against which alert and notification systems are reviewed have come under scrutiny in Atomic Safety and Licensing Board litigation and FEMA has defended the adequacy of the current standards. Efforts are underway to place the Outdoor Sound Propagation Model used in the alert and notification system reviews into FEMA's Integrated Emergency Management Information System for application to civil defense programs, hazardous materials program, and other programs in and outside of FEMA.
Design of alert and notification systems
Authors: Sutherland Louis C. , Stusnick Eric
Published: October 2005

Alert and notification systems are required by the Nuclear Regulatory Commission around nuclear power plants to provide a means of alerting the public within a 10-mile radius of a possible emergency condition that may require evacuation. The most common method of accomplishing this is through the use of audible signals from high-powered sirens. The basic problems involved in the design of such systems are discussed. These problems include specification and validation of the siren output signals, the prediction and validation of the siren signal as received in the community, and nonacoustic factors such as siren installation and control. General characteristics of currently available siren systems—both electromechanical and purely electronic types—are also briefly reviewed. Statistical aspects of short-term (second to second) and long-term (day to day) variations in siren signal levels received in the community are discussed, and this variation in the warning signal level is evaluated with respect to overall system effectiveness. Other means of conveying the warning, including the presentation of altering messages over automatically energized radios and siren-equipped emergency vehicles, are also briefly considered.
Outdoor sirens: How do they work for people indoors?
Authors: Keast David N.
Published: October 2005

People are normally indoors where the sounds from outdoor warning sirens are greatly attenuated by building structures. Nevertheless, practical experience and the results of tests by the Federal Emergency Management Agency and others have shown that siren sounds are quite effective for alerting large populations—including those indoors. Why is this so? Based upon data in the literature, three possible explanations are examined in this paper: (1) the possibility that the sounds from sirens outdoors, even though attenuated through building structures, are still sufficient to directly alert people indoors; (2) the possibility that people indoors are more responsive to siren sounds than people outdoors; and (3) the possibility that people indoors are alerted by other people who are outdoors when they hear the siren sounds. This examination indicates that all three mechanisms could be contributing to the effectiveness of siren sounds indoors. Their relative significance is not known, but probably varies with geographic location, weather conditions, and time of day.
Acoustic scattering from an elastic prolate spheroid in a shallow-water waveguide
Authors: Sammelmann Gary S. , Hackman Roger H.
Published: October 2005

The bistatic scattering of a broadband acoustic pulse from an elastic prolate spheroid in a shallow-water waveguide is studied. The calculation is based on the formal solution to the scattering in an inhomogeneous-layered waveguide presented at a previous meeting of the Acoustical Society [R. H. Hackman and G. S, Sammelmann, J. Acoust. Soc. Am. Suppl. 1 81, S42 (1987)]. The waveguide is assumed to be bounded from above by a sound soft air-seawater interface, and from below, by a rigid sediment-seawater interface. The sound speed is taken to be a monotonically decreasing function of depth. The emphasis of this study is on extracting elastic information from the scattered waveform. The importance of the rescattering of the acoustic pulse between the boundaries and the target is also studied.
Acoustic scattering from large aspect ratio, axisymmetric shells
Authors: Hackman Roger H. , Todoroff Douglas G.
Published: October 2005

The spheroidal-coordinate-based transition matrix has been successfully applied to the solution and the analysis of the acoustic scattering from large aspect ratio solids [R. H. Hackman and D. G. Todoroff, J. Acoust. Soc. Am. 78, 1058–1071 (1985)]. However, this approach required special care due to the existence of elastic states that were weakly coupled to the external acoustic field. Here, a new version of the spheroidal formalism is presented, one with improved stability and which is better suited to thin shells. This approach is applied to the acoustic scattering from a large aspect ratio, elastic prolate spheroidal shell of constant thickness. Theoretical predictions are compared with experimental measurements, and a physical explanation is given for the more prominent features in the backscattered formfunction.
Comparison of quadratic and piecewise-constant boundary element solutions of the surface Helmholtz equation
Authors: Shirron Joseph J.
Published: October 2005

A comparison of the accuracy and computation time of two different boundary element solution techniques for the surface Helmholtz equation of a rigid scatterer is presented. In the simplest case, the body's surface is represented by an assemblage of planar triangles, over which the surface pressure is taken to be constant. In the more sophisticated case, quadratic-isoparametric elements are used. Results are presented for the comparison of rates of convergence with mesh size and CPU times for the two methods. The effects of varying the order of Gaussian quadrature are shown. Further results are given comparing the efficiency of Schenck's algorithm for eliminating the nonuniqueness problem at the body's interior eigenvalues with the modified Green's function technique of D. S. Jones. The quadratic-isoparametric solution method together with Schenck's algorithm is found to be the more efficient means of obtaining an approximate solution to the surface Helmholtz equation. [Work supported by Naval Research Laboratory, Washington, DC.]
Measurements of Rayleigh wave scattering at a corner
Authors: Nagy Peter B. , Adler Laszlo
Published: October 2005

The problem of Rayleigh wave scattering in a homogeneous, isotropic wedge by experimental means was investigated. For an incident Rayleigh wave, reflected and transmitted Rayleigh waves are generated, as well as longitudinal and transverse cylindrical bulk waves initiated by the virtual source at the corner line. Sector-shaped test pieces were used, which focused back the diverging bulk waves to the same corner line after normal reflection at the cylindrical surface. By this simple geometry, both the phase and amplitude of all four components were able to be measured. Experimental results are presented to show the varying energy partition among these modes as a function of wedge angle from 90° to 150° in aluminum. Furthermore, the Rayleigh wave reflection and transmission results are compared to recent theoretical predictions by Gautesen [Wave Motion 9, 51–59 (1987)]. [This work was supported by the U.S. Department of Energy, Basic Energy Sciences, Grant DE-FG02-84ER45057.A004.]
Farfield patterns of rigid nonaxially symmetric obstacles: Example calculations using the Waterman scheme for approximation of the T matrix
Authors: Sarkissian Angie , Dallas Allan G.
Published: October 2005

To our knowledge, there have been no reports of numerical applications of the Waterman scheme to rigid scatters of nonaxially symmetric geometry. Here, the results of computations for various slender obstacles of this sort are described. Emphasis is placed upon the amount of work required for such calculations (relative to that necessary for axially symmetric shapes) and upon specific details, such as the numbers of spherical waves and quadrature points required.
The effect of finite surface acoustic impedance on sound fields near a smooth diffracting ridge
Authors: Zhou Ji-xun , Kearns James A. , Berthelot Yves H. , Pierce Allan D.
Published: October 2005

Laboratory scale experiments using spark sources are being conducted to study long-range propagation of sound over hills and valleys. The effect of the finite impedance of the diffracting scaled hill on the acoustic field is investigated, with either plywood or plywood covered with carpet. Particular attention is given to the case of small grazing angles of incidence of the sound wave on the diffracting surface. The model of Delany and Bazley is used to determine the impedance of the material from the value of the effective flow resistivity σ. The insertion loss of the scaled ridge is inferred from measurements of the ratio of the Fourier transforms of the diffracted pressure field to that of the free field, with subsequent digital signal processing performed in the frequency domain. Experimental data are compared with the theory of matched asymptotic expansions [J. Acoust. Soc. Am. Suppl. 1 79, S30 (1986)] for situations where the diffracted acoustic pressure is measured either along the ridge, or along a vertical axis at the apex or behind the ridge. [Work supported by NASA, Langley Research Center.]
Explorations on the difference in SRT between a stationary noise masker and an interfering speaker
Authors: Festen Joost M.
Published: October 2005

For moderate hearing impairment, the speech-reception threshold (SRT) for sentences in stationary noise is roughly up to 5 dB higher than for normal hearing. However, a fluctuating interfacing sound seems more typical for everyday listening conditions than stationary noise. For a group of young hearing-impaired listeners, the difference in SRT with normal-hearing listeners increased from 2.7 dB for stationary noise to 7 dB for 100% sinusoidally intensity-modulated noise, and even to 10.5 dB for interfering speech. In this experiment, the interfering speech was the time-reversed voice of the same speaker as the signal, which may have introduced an extra difficulty. In a subsequent experiment, the SRT for sentences from two speakers (one male and one female) was measured with a variety of fluctuating maskers covering the range from stationary noise to interfering speech. The two voices were mutually used as masker, giving a meaningful interference. Meaningless interference was obtained by time reversal of the interfering speech or by modulating noise with the envelope of speech. Two types of modulation were used: one broadband and one in which high- and low-frequency noise (separation frequency 1000 Hz) was modulated with the high- and low-frequency envelope of speech, respectively.
Correlations among auditory functions in the “normal” range
Authors: Haggard Mark , Saunders Gabrielle , Gatehouse Stuart
Published: October 2005

To date, hearing levels and pyschoacoustic measures have shown factor structure and correlations with speech perception in noise among the hearing impaired, but not among clinically “normal” ears. A pseudofree-field sentence-in-noise test (PFFIN) from a dummy-head recording, simplified psychoacoustic tuning curves, and tests of linguistic processing were administered to 60 people with hearing better than 20 dB HL (0.5–2.0 kHz); one-third had complained of auditory difficulties. Significant correlations were found among the psychoacoustic variables, which also predicted PFFIN score. Correlations between hearing levels and PFFIN remained significant after partialing age, noise exposure, upward spread of masking at 2 kHz, and educational and linguistic measures. Systematically truncating the HL distribution showed that this correlation lies mostly in the 15–25 dB HL range and implicates low- as well as high-frequency hearing. Thus the 17% of the adult population between 15 and 25 dB HL (0.5–4.0 kHz) should be considered marginal, both clinically and experimentally. Scientifically, if not pragmatically, a “low fence” at 15 dB HL is justified.
Evaluating the Articulation Index for auditory-visual input
Authors: Grant Ken W.
Published: October 2005

The current standard for calculating the Articulation Index (AI) includes a procedure to estimate the effective AI when hearing is combined with speechreading [ANSI S3.5-1969 (R1978), “Methods for the Calculation of the Articulation Index” (American National Standards Institute, New York, 1969)]. This procedure assumes that the band-importance function derived for auditory listening situations applies equally well to auditory-visual situations. Recent studies have shown, however, that certain auditory signals that, by themselves, produce negligible speech reception scores (e.g., F0, speech-modulated noise, etc.) can provide substantial benefits to speechreading. The existence of such signals suggests that the band-importance function for auditory and auditory-visual inputs may be different. In the present study, an attempt was made to validate the auditory-visual correction procedure outlined in the ANSI-1969 standard by evaluating auditory, visual, and auditory-visual sentence identification performance of normal-hearing subjects for both wideband speech degraded by additive noise and bandpass-filtered speech presented in quiet. The results obtained for auditory listening conditions with an AI greater than 0.03 support the procedure outlined in the current ANSI standard. [Work supported by NIH.]
Acoustic power radiation by cylindrical stiffened shells
Authors: Laulagnet B. , Guyader J. L.
Published: October 2005

Sound radiation by finite cylindrical stiffened shells, in light or heavy fluid, is studied using modal calculation. Numerical results on power radiation, shell quadratic velocity, and radiation factor are given, and the influence of parameters like stiffeners distribution, stiffener and shell damping, type of excitation, etc., is discussed. Finally the analysis of shell modes that contribute most to the radiation is presented. It is shown, in particular, that modes whose structural losses equal radiation losses dominate the power radiation, whatever the fluid (however, for light fluids, these modes have high radiation efficiency and low radiation efficiency for heavy fluids). This analysis allows the understanding of radiation curve singularities, and shows that critical frequency phenomena are completely different for heavy and light fluids. [Work supported by the Ministère de la Défense Contrat D.R.E.T.N° 85-065.]
Wave effect correction to reciprocity calibration results of vibration primary standards
Authors: Ge Li-Feng
Published: October 2005

The paper reveals the stress wave effect (SWE) on reciprocity calibration results of vibration primary standards and derives exact correct formulas of mechanical standards according to reciprocity theory and stress wave theory. The paper further expounds that both the electrodynamic reciprocity method (ERM) and the piezoelectric reciprocity method (PRM) need this correction at higher frequencies and shows that taking this measure can eliminate a system error of 10−2 to 10−3 orders of magnitude.
Relationship between the impedances and the reflection and transmission coefficients of a junction
Authors: Maga L. J. , Maidanik G.
Published: October 2005

A junction constitutes the coupling between dynamic systems. In this case, the one-dimensional dynamic systems so coupled are characterized by their wavenumbers and mass densities. The interface impedances of the dynamic systems at the junction may then be defined. The junction may be defined in terms of a junction impedance matrix. The nature of this matrix will be discussed. This matrix, together with the interface impedances of the dynamic systems, may then be employed to derive the junction interaction matrix, which consists of reflection and transmission coefficients. The manner and results of this derivation will be discussed and a few examples will be cited.
Damping and vibration analysis of bonded beams with a lap joint
Authors: Rao Mohan D. , Crocker Malcolm J.
Published: October 2005

In this paper, a theoretical model to calculate the loss factors and the resonance frequencies of flexural vibrations of a system of two parallel beams bonded with a single lap joint by a viscoelastic material has been developed. First, equations of motion of the joint region are derived using a differential element approach considering the transverse displacements of the upper and the lower beam to be different. The normal force between each beam and the adhesive layer is represented by a Pasternak base model, which consists of closely spaced linear springs. The shear force at the interface is modeled using a viscous model for friction. The resulting equations of motion, together with equations of transverse vibrations of the beams away from the joint, are solved using motion continuity conditions and boundary conditions at the free ends of the beams. Equations for calculating the resonance frequency and the loss factor for the case of clamped-clamped boundary conditions are then derived. Numerical results are generated and are compared with experiments for a system of two beams with a simple lap joint made of graphite epoxy composite material. [Work supported by NASA-MSFC.]