bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of visual information from a talker's face in the processing of place and manner features in speech
Authors: Green Kerry P. , Kuhl Patricia K.
Published: October 2005

A number of studies have indicated that a dependency relation exists for the processing of place and manner features of articulation. Other studies have demonstrated that visual information provided by a talker's face can influence the perceived place of articulation of well-specified auditory tokens presented in synchrony with the visual information. Thus, when /bi/ is presented auditorially and /gi/ visually, a person perceives the talker as saying /di/. These findings raise the possibility that visual place information might also influence the processing of VOT. Members of an auditory continuum ranging from /ibi/ to /ipi/ were paired with a video display of a talker saying /igi/. The auditory tokens were heard as ranging from /ibi/ to /ipi/, while the audio/visual tokens were perceived as ranging from /idi/ to /iti/. We found that the VOT boundary for the audio/visual tokens was located at a significantly longer value than the VOT boundary for the auditory continuum presented without the visual information. These results indicate that, under certain circumstances, the processing of VOT information takes into account both auditory and visual place information. [Research supported by NIH.]
Distribution of sounds within and between Spanish syllables
Authors: Guirao Miguelina , Jurado María García
Published: October 2005

The data presented in this work area complement to a previous statistical count [M. Guirao and M. García Jurado, J. Acoust. Soc. Am. Suppl. 1 78, S55 (1985)]. A corpus of 68141 syllables distributed in 159464 phonemes was used. This time our attention was oriented toward (a) distribution of sounds in each one of four syllabic positions, and (b) distribution in final position according to number of elements in the syllable. The first count indicates that fricative /s/, bursts /t k d p b/, and periodic sounds /n m l r/ cover about 80% of all items in first position. The second position in syllables of two or more components (64572 syllables) is taken mainly by vowels /e a o/. In the third position (22736 syllables) predominate /s/, /e a/, and /r n/. In the remaining syllables (3956) only /n/ and /s/ were found in the fourth position. The second count indicates that final sounds in two components syllables are vowels, 96%. With three components, /s n r/ scored 58%, /a e/ 24%, and /1/ 12%. With four, /n/ 40%, /s/ 29%, and /l r m/ 16%. With five components, /n/ 58%, /s/ 30%, and /l/ 5%. Sounds are classed according to their position and distribution within and between syllables.
Use of SALT tables for rapid calculation of sound angle, level, and travel time
Authors: Bucker Homer P.
Published: October 2005

There are cases where a very quick calculation of sound propagation is required. One example is a real-time torpedo simulator where only a fraction of a second is available to determine sonar returns. Another example is a bistatic reverberation model where thousands of scattering elements must be included in a realistic model. A SALT table is a list of sound angle, level, and travel time listed as a function of range from the source or receiver. The number of tables used depends upon available computer storage and time available to access the data in the tables. This paper will discuss two algorithms for calculating SALT tables. In one method, the table is defined by the number of bottom reflections or ray turnunders. In the second method, the tables are numbered according to order of calculation. Several examples will be given showing reasonable agreement between calculations using SALT tables and those using more exact methods.
Finite-element analysis of marine sediment acoustics
Authors: Hassenzadeh Siamak , Teng Yu-chiung , Kuo John T.
Published: October 2005

The propagation of acoustic waves in a shallow water environment is controlled by the dynamic response of sediments, which are generally composite (multiphase) systems, as well as the complex geological structure that results from depositional processes. To analyze the propagation of low-frequency acoustic waves in such media, the finite-element-Biot model has been developed which incorporates the Biot's theory into the finite-element method. The Biot's theory governing the dynamic behavior of fluid-filled porous materials provides an adequate description of the effects of the intrinsic properties of the sediments, and the finite-element method has the flexibility to model large-scale inhomogeneities that are commonly encountered in marine environments. The effects of such parameters as porosity, lithology, lithification, and dissipation due to the relative motion of a viscous fluid are examined numerically. It is found that the modification of acoustic waves is a result of the intrinsic properties of fluid-saturated porous sediments as well as the interactions between the fast and the slow compressional waves and energy partitioning at interfaces between dissimilar fluid-filled sediments.
Non-Markov noise processes
Authors: Novak Stephanie , Fretwell Lyman J.
Published: October 2005

The simplest model noise process is Gaussian and uncorrelated. Measurements of ambient noise pressure in the ocean, however, show correlation between time samples. A stationary Gaussian random process has a correlation function that decays exponentially with time if and only if the process is Markov. Here, only stationary noise processes are considered, but the Markov assumption is relaxed. A general algorithm for constructing a non-Markov stationary time series is described. It is assumed that the statistics are Gaussian; however, the method can also be extended to include non-Gaussian statistics. The general algorithm is then applied to a special case. A model non-Markov noise correlation function consisting of a linear combination of two exponentials with two different correlation time constants is fit to an experimental correlation function. Time series for uncorrelated, Markov and non-Markov noise processes are generated from the same sequence of random numbers and compared. Comparisons are made with observed time series. Consequences regarding signal detection are discussed.
Nonlinear and non-Gaussian ocean noise
Authors: Brockett Patrick L. , Hinich Melvin , Wilson Gary R.
Published: October 2005

Bispectral analysis is a statistical tool for detecting and identifying a nonlinear stochastic signal generating mechanism from data containing its output. Bispectral analysis can also be employed to investigate whether the observed data record is consistent with the hypothesis that the underlying stochastic process has Gaussian distribution. From estimates of bispectra of several records of ambient acoustic ocean noise, a newly developed statistical method for testing whether the noise had a Gaussian distribution, and whether it contains evidence of nonlinearity in the underlying mechanisms generating the observed noise is applied. Seven acoustic records from three environments are examined: the Atlantic south of Bermuda, the northeast Pacific, and the Indian Ocean. The collection of time series represents both ambient acoustic noise (no local shipping) and noise dominated by local shipping. The three ambient records appeared to be both linear and Gaussian processes when examined over a period on the order of a minute, but were found to be nonlinear and non-Gaussian when examined over shorter time periods on the order of a second. In each case, the time series dominated by local shipping noise tested to be nonlinear and non-Gaussian over both short and long time periods.
Contribution of sources over slopes to midocean ambient noise vertical pattern
Authors: Murphy Donald A. , Authement Mona J.
Published: October 2005

The shape and depths of notches in the midocean vertical ambient noise patterns are heavily affected by arrivals from sources over continental slopes [D. A. Murphy and D. R. Del Balzo, J. Acoust. Soc. Am. Suppl. 1 77, S3 (1985)]. The steep angle and bottom interacting parabolic equation program PAREQ was used to simulate the field at the Contrack VI site in the Northeast Pacific due to sources over the slope. The assumed depths and distances down the slope of the noise sources were varied and the contributions were added to those of previously calculated sources to calculate the ambient noise field. For noise sources at short distances down the slope, the sensitivity to noise source depth was not significant. The distance of the noise source down the slope was important in calculating the shape of the vertical noise notches.
Directional underwater noise estimation
Authors: Bannister R. W. , Burgess A. S. , Kewley D. J.
Published: October 2005

In the waters surrounding Australia and New Zealand, there are features of the measured three-dimensional ambient noise field (20–200 Hz) which appear similar to those found in the northern hemisphere where shipping noise is dominant. In the latter case, this shipping noise can be enhanced when vessels are at high latitudes or over sloping bathymetry. However, in the southern hemisphere, there are fewer ships, negligible numbers over suitable bathymetric slopes, and practically none at all at high latitudes. This apparent inconsistency in interpretation of the broad features between the different hemispheric noise data had led to the development of the directional underwater noise estimates (DUNES) model for ambient noise. The model includes wind-generated noise from local, bottom bounce, RSR, and RR path sources. The last sources include the high latitude winds and continental or seamount slope enhanced wind noise [R. W. Bannister, J. Acoust. Soc. Am. 79, 41–48 (1986)]. The same wind-generated surface source levels {based upon upgraded values [A. S. Burgess and D. J. Kewley, J. Acoust. Soc. Am. 73, 201–210 (1983)]} are used for each source location and when combined with an appropriate transmission process produces predictions of vertical noise directionality and resulting omnidirectional noise. Features included are a speed and frequency-dependent wind-source depth, season, latitude, depth, and bottom reflection loss dependences, and specific shipping sources, with or without slope enhancements. Comparison with vertical directionality data shows that the levels and frequency relations of the various angular components match well.
Sound insulation for buildings under Part 150
Authors: Tedrick Richard N.
Published: October 2005

Part 150 of the Federal Aviation Regulations provides a mechanism for the operators of noise-impacted airports to develop comprehensive programs to limit or reduce noise effects, including noncompatible land uses. In developing these programs, the airport operator is required to consult both with the users of the airport and with local, state, and federal agencies having land-use planning authority. These groups then examine various alternative operational and land-use actions and devise a plan suited to local conditions. One option for decreasing noncompatible uses is sound insulation of buildings in impacted areas. In fact, Part 150 itself cites several combinations of uses and aircraft sound levels that require specified noise level reductions to be considered compatible. Obviously sound insulation can be installed as a part of the original building design; however, in many cases, additional insulation may be required. Oftentimes, this supplemental insulation is eligible for funding under the federally funded Airport Improvement Program. Of the 31 noise compatibility programs that have been submitted to date, 20 have included planned increases in sound insulation in one or more structures.
Design and field experience in the sound insulation of dwellings around airports
Authors: Brown David
Published: October 2005

Remedial sound insulation is currently being considered, and in some cases being applied, as an aircraft noise mitigation option for residential land uses around airports. Such large-scale programs incur very large expenditures of funds and therefore need to be carefully assessed in terms of both objective and subjective merits. This paper reviews two separate programs applied to dwellings around Los Angeles International Airport and their implications for projects at other airports. Each of the topic programs was applied to a sample of dwellings representative of typical construction and different noise exposure conditions around the airport. The more recent program, completed in 1985, is emphasized, as it provides an insight to current noise conditions within dwellings near airports. Specific case histories are illustrated in terms of design features; technical, aesthetic, and subjective acoustical merits; and cost implications. The paper also addresses acoustical design theory in its application to this particular type of problem area.
Logan International Airport sound isulation program
Authors: Stiffler Ardis
Published: October 2005

In 1985, MASSPORT completed a residential sound insulation pilot project in four homes in Fast Boston and Winthrop. The homes were of construction typical of their neighborhoods and exposed to various types of aircraft noise. The acoustical treatments were successful in reducing the interior levels of noise. In October 1985, the MASSPORT Board directed that the residential sound insulation project continue with acoustical work on 150 more houses. By December 1986, construction modifications of a number of these houses should be completed. The presentation will cover the administrative organization and the acoustical requirements of the program, and will describe the procedures and approach of such a program from both the airport and the community point of view. Information will also be presented on the acoustical testing methods used by BBN Laboratories, acoustical consultants for the program, in the field before and after construction modifications.
Exterior noise spectra and interior noise
Authors: Segal Alexander
Published: October 2005

A statistical analysis was performed in order to determine the impact of different published exterior traffic noise spectral envelopes upon interior noise levels. it was found that the same exterior A-weighted sound level attributable to different traffic noise spectra produces interior sound levels ranging within 3 or more dB. The difference in interior noise levels is significantly affected by the building envelope element combinations. The effect of the relative size of building elements is less pronounced. Several traffic noise spectra were generated by computer for typical traffic speeds and mixes. Their application allowed significantly reduced variability of the interior noise results. Taking into account numerous interior noise analysis, currently performed in order to satisfy interior noise regulations, some unification of the exterior noise spectra information appears to be urgent.
TANDEL measurement of hydroacoustical particle motion
Authors: Alexandrakis G. C. , Rittenmyer K. M. , Dubbelday P. S.
Published: October 2005

A new ferroelectric sensor for measuring the particle motion in hydroacoustic fields has been developed. The sensor is a capacitor constructed by adding conducting end plates to single crystals or polymer composites of antimony sulfur iodide (SbSI). The device is operated above the Curie point of about 20 °C. The heating is accomplished through the hysteresis cycle driven by a Sawyer-Tower-type bridge. In the temperature region slightly above the Curie point, both the real part ε′ and the imaginary part ε″ of the dielectric permittivity have a large negative slope as a function of temperature. The negative slope in ε″ causes the Temperature Autostabiling feature of the Nonlinear Delectric ELement (TANDEL). Cooling the sensor by a fluid flow changes the temperature of the sensor, and consequently ε′ and ε″. The change of ε′ unbalances the bridge, producing a detectable signal. The output for steady flow shows the characteristic exponential dependence on fluid speed. The sensor displays directional sensitivity. The response to low-frequency acoustic fields is discussed and related to the heat transfer properties of horizontal cylinders. [Work supported by the ONR.]
Decomposing one-dimensional acoustic pressure response into propagating and standing waves
Authors: Spiekermann Charles E. , Radcliffe Clark J.
Published: October 2005

Few actual sound fields are representative of ideal acoustic pressure responses and ideal boundary conditions, such as those found in anechoic or reverberant rooms. Normally encountered enclosures have complicated responses that are difficult to relate to a boundary condition that is in between these two ideal extremes. Yet, the propagating and standing wave responses associated with absorptive and reflective boundary conditions seen in the ideal cases are fundamental bases to understand these more complicated problems. An analytical method is developed to decompose a one-dimensional acoustic pressure response associated with a specified partially absorptive boundary condition into an equivalent summation of propagating and standing waves usually associated with absorptive and reflective boundary conditions, respectively. The propagating and standing wave responses are scaled and shifted in phase by factors that are dependent on the boundary absorptivity and frequency, but are independent of the spatial location. The complicated mixed response is decomposed into varying amounts of the ideal responses, which can be helpful during a design analysis.
Analysis of multiply coupled, multimode sonar transducer arrays
Authors: Thompson Stephen C. , Johnson Michael P.
Published: October 2005

Sonar transducer element and array performance predictions using linear analysis methods have been usefully performed for over two decades. These analyses were first performed for single degree of freedom (DOF) piston transducers including only the acoustical coupling through the radiating medium. More recently, single DOF transducers including both acoustical and mechanical coupling through their common mounting surface have been analyzed [D. T. Porter, J. Acoust. Soc. Am. Suppl. 1 78, S73 (1985)]. However, many of the transducer types currently under consideration for use in sonar arrays are multiple DOF systems having two or more resonant modes of significance within their operating frequency band. Flextensional and flexural mode transducers, as well as several types of multimode or multiply resonant piston transducer structures, are examples of multiple DOF elements. A general method for the analysis of multiply coupled, multiple DOF transducer arrays will be presented. The equations describing the general case have the same form as those used previously. As a consequence, many of the lessons learned from experience on arrays of single DOF elements can be extended in a straightforward manner. As an example, the concept of velocity control will be explored in different examples of multimode arrays. It will be shown that velocity control can be achieved in only a special class of multimode transducer elements—those having as many control ports (i.e., electrical) as there are structural modes.
Stripping the one-dimensional acoustic pressure response into propagating and standing wave components
Authors: Spiekermann Charles E. , Radcliffe Clark J.
Published: October 2005

Most realistic boundary conditions are partially absorptive, with the rest of the incident acoustic power being reflected. This results in a response that can be viewed as a summation of propagating and standing wave effects. A one-dimensional, measurement-based, two-microphone spectral analysis technique is developed which Separates the Total acoustic Response Into Propagating and Standing (STRIPS) wave components. STRIPS uses measurements that contain implicit information about the boundary condition to extract the propagating and standing wave components. These sum to be the total system response without requiring explicit knowledge of the particular boundary condition. An exact decomposition example for a one-dimensional acoustic pressure model with a known mixed boundary condition is used to validate the STRIPS method. The utility of the STRIPS method is demonstrated using experimental measurements from a tube as input to STRIPS to obtain the propagating and standing wave pressure components. Changes in experimental boundary absorptivity are seen in the STRIPS results when a flared end is attached to the tube.
Rapid, electronic measurement system for determination of dc flow resistances
Authors: Stinson Michael R. , Daigle G. A.
Published: October 2005

A measurement system will be described which allows dc flow resistances (1 to 104 cgs ohms) of various samples to be determined quickly and accurately. Variable-capacitance pressure transducers are used to measure pressure differences across both the test sample and a laminar flow element with known resistance (these being in series), so that the unknown resistance can be calculated directly. The rate of flow of air through the sample is adjusted using a mass flow controller; flows of 10−3−1 cm3/s can be contolled to better than 1%. The use of these electronic sensors permits measurements of flow resistance to be made much faster than with the traditional Leonard device. Initial measurements of flow resistance (i.e., the zero frequency limit of acoustic resistance) have been made on small, circular orifices in thin plates.
An acoustic scoring system for a helicopter gunnery range
Authors: Davey Robert F.
Published: October 2005

A system has been developed which measures the position of the impact of munitions fired from helicopters by determining the arrival time of the detonation sound. The signals from acoustic transducers are digitized and then processed by a detection algorithm to determine the arrival time of the leading edge of the acoustic signature. The difference in the arrival times at three transducers establishes the location of the sound source as the intersection of two hyperbolas. Field tests of a prototype system were conducted to identify the most desirable acoustic transducer, to examine the effect of propagation through dense vegetation on the detonation signature, and to verify the accuracy of the computational algorithms. The results showed that the signals from low-frequency speakers can be detected more reliably than those from midrange driver/horn systems. With properly selected speakers sited in a triangular array, the detonation position was established to an accuracy of about 2 m. An analysis of the system performance shows that such techniques can be extended to score impacts over an area as large as 1 km2.
Paging system design concepts
Authors: Gharabegian Areg
Published: October 2005

A new in-plant paging and emergency evacuation alert system was designed for indoor and outdoor areas of a nuclear power generating station and all support areas. The new system was designed to provide intelligible message transmission during all modes of plant operation and for day-to-day paging and emergency announcements. A comprehensive microcomputer-based acoustic analysis using Lotus 1-2-3 spread sheet software was performed to ensure intelligible speech coverage. The articulation index procedure stated in ANSI Standard S3.5 1969 was the basis for this analysis. Gated time mode measurements were conducted for the complex areas to evaluate direct-to-reverberant ratios because use of the measured reverberation time for the acoustic calculations produced unrealistic results. Based on the results of these measurements, the critical radius was calculated for different types of speakers in various areas. To provide an intelligible speech coverage, a total of 4335 new speakers, 4058 for indoor use and 277 for outdoor use, were designed. Nine different types of speakers with different power levels and directivity were utilized for this system.
Radio as a forum for acoustics
Authors: Metzner Jim
Published: October 2005

In the context of contemporary electronic media, particularly radio, what are the challenges which face both scientist and broadcaster in presenting a scientific subject—specifically in the area of acoustics—to a general audience? The aim is to inform simply and accurately, without trivializing the subject, while taking into account that the listening audience may have little—if any—background in the field being discussed. Examples will be presented from “The Sounds of Science,” an award-winning short-format daily radio series produced by the author for The DuPont Company, and distributed to over 100 public and commercial radio stations nationwide. The series uses a blend of interview and ambient sound to convey an experience of scientific research and ideas. Subjects treated in the domain of acoustics include early woodwind instruments, the sound of a space launch, Tibetan chant, and sound paradoxes. The preparation and conditions for interviews, which help to establish an exchange meaningful to both parties, will be discussed. A collaboration is fostered in which the scientist often plays an active role in how best to portray his or her research in sound.
Sound through music: Exhibit-based teaching at the Exploratorium
Authors: Humphrey Thomas
Published: October 2005

Acoustical topics taught at the Exploratorium include speech, hearing, language, psychoacoustics, and the physics of sound. We have found that each of these topics can be reached easily by beginning with a discussion of music. The evolution of the western scale, musical composition, and the design of musical instruments involve the concepts of a vibrating string and its harmonics, logarithmic hearing, acoustic resonance, and physical beats. The broadness of this approach leads naturally to discussions of the bases of aesthetics, the ability of the sciences to contribute to an appreciation of the arts, and the natural creative relationship between artists and scientists. The exhibits used in this exploration are all hands-on, allowing for a variety of approaches to teaching. The students use the exhibits both on their own and with the guidance of an Exploratorium teacher. Independent use allows for self-discovery, while the guide can provide direction toward less obvious observations. Classroom discussions typically follow the floor work.
The CSULB Mobile Science Museum: Sights and sounds of science
Authors: Schaadt Michael S.
Published: October 2005

In 1980, a 27-ft recreational vehicle was adapted to carry interactive science displays to local schools and community groups. This Mobile Science Museum (MSM) exhibits as many as 40 individual hands-on displays both inside as well as on tables directly outside the vehicle. University science students serve as docents and pass on their enthusiasm for science while providing role models for young visitors. Most displays are borrowed from university science teaching and research laboratories, while others are developed and fabricated by faculty, staff, and students. Topics found to be particularly effective for presentation in the hands-on mode include sound, light, and marine biology. Far more schools request visits by the MSM than can be served within current budgetary constraints. While this project is supported by CSULB, School of Natural Sciences, the majority of the operating budget comes from other sources of funding, including companies specializing in science and technology, school districts, parent/teacher associations, and private individuals.
Computer microworlds for sound and music
Authors: Balzano Gerald J. , Dolson Mark
Published: October 2005

Computers are increasingly being used both for education in acoustics and for making music. But frequently the computer is used merely to automate an established paradigm. Thus we have the spectacle of music students using the computer as a drill-and-practice machine, of musicians using the computer as a sophisticated tape recorder, and of students in acoustics using the computer as a data-acquisition-and-plotting tool in laboratory experiments. In a more innovative “microworld” approach, the computer is the laboratory. In the SESAME project, we are designing a set of Structured Environments for Sound And Music Exploration in which students and professionals alike can use the computer to design their own musical and/or acoustical experiments. But this is feasible only with software that shields users from the machine-oriented details of conventional programming languages, allowing users to think and program directly in terms of sonic and musical structures. During the past year at U. C. San Diego we have begun working toward this goal, using the IBM-PC to control both synthesizers and digital-to-analog converters. In this report, we present some preliminary results of several examples of computer environments for sound and music appropriate for both learning and research. [Work supported by the Department of Education, Fund for the Improvement of Post-Secondary Education.]
Laboratory and demonstration experiments with guitars
Authors: Rossing Thomas D.
Published: October 2005

Several interesting demonstration and laboratory experiments can be done with acoustic and electric guitars. Some of these deal with vibrations of the strings, some with the resonances of the body, and some with sound radiation from the guitar. Doing physics experiments with musical instruments increases student interest.
Shape characterization from the complex poles of the acoustic scattering amplitude
Authors: Gaunaurd G. C.
Published: October 2005

It was found that every penetrable scatterer has a peculiar set of poles in the lower half of the complex-frequency plane (x = ka). Some of these poles depend only on shape while others depend only on composition. The poles are labeled by two indices (n,l). Changes in shape for a given composition, changes the location of the “shape poles.” Symmetric pole patterns with respect to the imaginary axis (Im x) are indicative of bodies close to the spherical shape. Asymmetric pole patterns with respect to Im x are indicative of elongated cylindrical shapes viewed at normal incidence. The peculiar pole asymmetry of the cylindrical shape is due to the presence of an additional branch of poles that shifts the symmetry of all the other poles. A study of these poles is presented indicating: (1) How to distinguish poles due to body shape from those due to composition; (2) How the pole positions change as the composition changes from the very stiff to the very compliant limits for a given shape; (3) How to look for the identifying symmetries or asymetries; (4) How to recognize the shape when only a limited number of poles are available; and (5) How noise levels make the pole-positions random, and known only within “uncertainty circles.”
Coupled finite element and boundary element capability for acoustic scattering from general structures
Authors: Everstine Gordon C. , Schuetz Louise S.
Published: October 2005

A coupled finite element/boundary element capability is described for calculating the sound pressure field scattered by an arbitrary submerged 3-D elastic structure. Structural and fluid impedances are calculated with no approximation other than discretization. The surface fluid pressures and velocities are first calculated by coupling a finite element model of the structure with a discretized form of the Helmholtz surface integral equation for the exterior fluid. Farfield pressures are then evaluated from the surface solution using the Helmholtz exterior integral equation. The formulation is validated using known analytic solutions for scattering from submerged spherical shells.
Numerical approach to acoustical scattering from objects in a waveguide
Authors: Werby M. F. , Norton Guy
Published: October 2005

Scattering from submerged objects in a free environment has been a problem of considerable interest for the past several years. Several approaches have yielded interesting results due to continued improvements in numerical schemes. The problem of scattering in a confined environment has proven more difficult to formulate in a form useful for calculation due to the coupling of effects from the scattered object with that of the boundaries. The purpose of this work is to propose a numerical scheme that enables one to describe adequately scattering from an elongated object in an environment capable of producing a guided wave. The method is then applied to scattering from an elongated rigid spheroid in a waveguide.
Acoustic backscatter from highly dense scattering arrays
Authors: Telschow Kenneth L.
Published: October 2005

Acoustic backscatter signals from several specimens containing high number densities of small spherical scatterers were measured in order to compare the signals obtained with those calculated from the independent scatterer model for the case of high scatterer concentration and long wavelengths. The scatterers were prepared by precipitation of less dense second-phase spherical particles from a glass host by controlling the melt chemistry and cooling rate. Statistics on the size, number, and distribution of the scatterers were obtained from microscopic observation. The results show that the backscatter signal energy measured is directly related to the mean interparticle spacing between scatterers. The reason for this relationship is shown, from the independent scatterer model, to come from the fact that the distribution of interparticle spacings can be represented by a Gaussian probability with a specified mean. Results of the calculation and comparison with experimental results illustrating the effect of the spacing distribution on the scattering structure factor are presented. [Work supported by the Interior Department's Bureau of Mines through Department of Energy.]
Backscattering of leaky Lamb waves from fiber-reinforced composite laminates
Authors: Jungman Alain , Nagy Peter B. , Adler Laszlo
Published: October 2005

Fiber-reinforced composite laminates were studied by analyzing the backscattered amplitude spectra of an incident broadband pulse. An extensive spatial averaging was carried out in the frequency domain to identify the coherent backscattering signals. For various angles of incidence the received signal was spectrum analyzed by using a digitized system. A set of curves were generated that clearly identified the source of backscattering as backscattered leaky Lamb waves. Results were generated by this method for different orientations of the fibers and compared to other ultrasonic techniques.
Scattering of acoustic waves by piezoelectric composites
Authors: Varadan V. K. , Ma Y. , Varadan V. V.
Published: October 2005

Piezoelectic composite materials can be designed so that they effectively alter the reflection and transmission characteristics of acoustic and electromagnetic waves that are incident on them. This can be achieved by controlling their microstructure so that their performance characteristics match desired goals. With this end in mind basic research has been performed on the propagation of elastic P, SV, and SH waves and electromagnetic waves propagating through a composite containing a random distribution of parallelly aligned, infinitely long cylinders made of a piezoelectric material that are embedded in a host material such as rubber. If elastic waves are incident on such a medium, both elastic and electromagnetic waves are produced due to the piezoelectric effect. We use a self-consistent multiple scattering theory that takes into account the interacting elastodynamic and electromagnetic fields as well as statistical correlations among the cylinders that enter the expressions for the average fields in this medium. The response of a single piezoelectric cylinder to applied elastic and electromagnetic fields is characterized by a T matrix. From the configurationally averaged fields, the effective elastic, electromagnetic, and piezoelectric properties can be obtained. In our computations, BaTiO3 fibers embedded in a rubberlike host material with different rigidities are considered. Numerical results are presented for both coherent phase velocity and attenuation as a function of frequency and concentration of the piezoelectric cylinders. To evaluate the piezoelectric effect in altering the propagation characteristics of the waves, the numerical results obtained are compared to those obtained suppressing this effect.
Numerical search for a breakdown of the Waterman algorithm for approximating the T matrix of a rigid obstacle
Authors: Sarkissian Angie , Dallas Allan G. , Kleinman Ralph E.
Published: October 2005

The convergence of the Waterman algorithm for approximating the T matrix [J. Acoust. Soc. Am. 45, 1417–1429 (1969)] has not been established for scatterers of general shape. One can prove that the convergence criteria of Kristensson, Ramm, and Ström [J. Math. Phys. 24, 2619–2631 (1983)] are never fulfilled if the obstacle is nonspherical and the spherical wave functions have their usual normalization; the proof of this fact shall appear elsewhere. One of the coordinate sequences of this algorithm is the family of regular spherical waves, which fails to be complete in L2 (Γ), Γ denoting the obstacle boundary, when k2 is an interior Dirichlet eigenvalue for the negative Laplacian. These circumstances lead one to conjecture that the method will fail at such frequencies (as it does for the sphere). The results of computations near various of these frequencies for spheroidal scatterers are reported. For the sphere, the widths of the ka intervals of instability are examined, while for the nonspherical case, the object is to determine whether a breakdown occurs at all.
Auditory duration discrimination in primates
Authors: Sinnott Joan M. , Owren Michael J.
Published: October 2005

Auditory duration DLs at 2 kHz were measured in Old World monkeys (Macaca, Cercopithecus) and humans using a repeating standard AX procedure and positive reinforcement operant conditioning techniques. For a 200-ms standard tone, monkey DLs (45–62 ms) were about 2–3 times larger than human (15–27 ms), Weber fractions (ΔT/T) for all species were smallest at standard durations of 200 and 400 ms and increased with decreasing standard duration. DLs for all species did not vary as a function of sensation level from 30 to 60 dB, but were elevated slightly at 20 dB. Monkeys experienced difficulty in discriminating duration decrements, in contrast to humans. Results are related to other comparative psychoacoustic data and vocal communication. [Work supported by NSF and the Guggenheim Foundation.]
Frequency and intensity dependence of the preferred firing phase of starling cochlear ganglion cells
Authors: Narins Peter M. , Gleich Otto
Published: October 2005

The preferred phase of firing of 28 cochlear ganglion cells in the anesthetized starling, was measured over a frequency range encompassing CF of typically 3 octaves and an intensity range of at least 30 dB. The phase versus frequency functions could be fit remarkably well by straight lines; the slopes of these functions represent the system delay between the stimulus onset and the occurrence of the spike at the recording electrode. After correction for acoustic and neural transmission, we find delays for tone stimuli of 90 dB SPL between 1.37 ms (for the highest-CF cells) and 2.40 ms (for the lowest CF cells). In addition, the slopes of the phase versus frequency functions, and hence the system delay, decrease with increasing stimulus intensity by 0.04 ms/dB. As in amphibians, reptiles, and mammals, the preferred phase of firing is nearly intensity-independent near CF, whereas increasing stimulus intensity above and below CF results in a progressive phase lead and lag, respectively. These results are discussed with respect to the underlying mechanisms of frequency analysis in the avian inner ear. [Work supported by the A.v. Humboldt Foundation, the SFB, and NIH.]
Marked differences in blood/perilymph kinetics of furosemide (FU) between scala tympani (ST), and scala vestibuli (SV). Paradoxical effect of probenecid (PR)
Authors: Hara Akira , Thalmann Ruediger , Salt Alec N.
Published: October 2005

Rybak et al. [J. Pharmacol. Exp. Therapeut. 230, 706–709 (1984)] demonstrated that i.v. injection of 100 mg/kg FU results in a rapid but transient accumulation of the drug in ST of the chinchilla (CH). We found a similar pattern in ST of guinea pigs (GP) (5 μg/ml, 15 min after 100 mg/kg i.v.), followed by a (gradual) decline to 0.8 mg/ml within 1 h. In SV (not studied by Rybak et al.) FU increased very slowly (0.8 μg/ml at 15 min) but continued to rise gradually (2 μg/ml at 1 h). Rybak et al. found that 50 mg/kg PR suppressed accumulation of FU, while we found only much higher dosages (200 mg/kg) to be effective in GP. Paradoxically, at low dosages (50 mg/kg) PR caused an increase of FU that persisted for prolonged periods. This suggests that the influx and outflux systems for FU at the blood/perilymph barrier of ST have a differential sensitivity to PR, perhaps analogous to the differential modification of methotrexate flux in and out of tumor cells in response to PR [Henderson and Zevely, J. Biochem. Pharmacol. 34, 1725–1729 (1985).]
Biochemical and biophysical properties of the tectorial membrane (TM)
Authors: Thalmann Isolde , Thallinger Gertraud , Thalmann Ruediger
Published: October 2005

It was recently reported [I. Thalmann et al., ORL 48, 107–115 (1986)] that 40%–50% of the guinea pig TM consists of collagen. We now provide further rigorous proof that most of the collagen consists of type II, and that also the minor cartilage collagens, 1α, 2α, and 3α, as well as collagen type IX are present. Thus, the TM contains the same types of collagen as hyaline cartilage. Moreover, we have shown by quick-freeze, deep-etch 3-D electronmicroscopy (3-D-EM) that at least the upper part of the TM consists of a dense tangle of fibrils (∼20 nm) which are indistinguishable from the type II collagen fibrils of cartilage. These fibrils are embedded in a dense meshwork of anastomotic material that looks similar to the proteoglycan gel observed throughout cartilage but which differs from cartilage in that its constituent strands look relatively thick and variably puffy. Although the majority of the noncollagenous proteins are also glycoproteins, it cannot yet be decided whether and to what extent they contribute to a second type of major fibril or to the gel matrix. The presentation will include a description of the dry weight of the TM as a function of cochlear location and an estimate of the dry-to-wet weight ratio. [Work supported by NSF; We thank Dr. J. Heuser for the 3-D-EM preparations.]
Some biochemical and physicochemical features of the spiral limbus-basilar membrane-spiral ligament complex
Authors: Thalmann Ruediger , Kellner Heinz J. , Comegys Thomas H. , Thalmann Isolde
Published: October 2005

It has been shown by immunohistochemical techniques that the predominant collagen of inner ear connective tissues is collagen type II [K. Tomoda et al. Ear Res. Jpn. 15, 199–202 (1984)]. It has now been confirmed by chemical techniques that collagen type II is also abundant in spiral limbus (LIM), basilar membrane (BM), spiral ligament (LIG); in addition, the “minor cartilage collagens” (1 a, 2a , 3a) and collagen type IX are present. No collagen was found in the stria vascularis (SV). In contrast to the situation with LIM and LIG, it was extremely difficult to extract collagen from BM, presumably because the fibers are embedded in a thick, dense “ground substance.” BM was homogenized vigorously with ultrasound and glass micro-beads, then digest with pepsin in order to release the collagen. Protein content of BM ranged from 21% to 28% of dry weight, in rough correspondence with the well-known differences in structural detail of the BM along the extent of the cochlea. In turn, collagen comprises from 36% to 44% of the total protein content. BM also contains appreciable levels of OCP-I and OCP-II, polypeptides previously assumed to be organ of Corti-specific. OCP-I and II are also present in very low concentrations in LIM and LIG, but not in SV. The significance of these findings will be discussed. [Work supported by NSF.]
Effects of aging and hearing loss on sentence reception in noise from one versus two sources
Authors: Gelfand Stanley A. , Ross Leslie , Miller Sarah
Published: October 2005

Duquesnoy [J. Acoust. Soc. Am. 74, 739–743 (1983)] found that elderly subjects with hearing loss do not take advantage of the separation of speech and noise sources to the same degree as young normals. However, it is not clear whether this finding was due to aging and/or the hearing loss. We addressed this issue using a sentence reception threshold (SRT) test developed by modifying the SPIN test, which produces data comparable to those obtained with the Dutch sentences. Here SRTs were obtained from young and elderly normal hearing subjects and an elderly hearing impaired group using sentences and noise presented from one speaker or from two speakers 90° apart. The impaired group performed more poorly than the normal groups in all conditions. The advantage derived from separating the speech and noise compared to presenting them from the same speaker was smaller for the impaired group than for the normal groups. The normal groups did not differ significantly. The reduced ability of the elderly hearing impaired subjects to take advantage of the separation of speech and noise appears to depend more on the hearing loss than aging, per se. [Work supported by the Veterans Administration.]
Vowel identification and vowel masking patterns of hearing-impaired subjects
Authors: Van Tasell Dianne J. , Fabry David A. , Thibodeau Linda M.
Published: October 2005

Confusion matrices for seven synthetic steady-state vowels were obtained from ten normal and three hearing-impaired subjects. The vowels were identified at greater than 96% accuracy by the normals, and less accurately by the impaired subjects. Shortened versions of selected vowels then were used as maskers; vowel masking patterns (VMPs) consisting of forward-masked thresholds for sinusoidal probes at all vowel masker harmonics were obtained from the impaired subjects and from one normal subject. Here VMPs of the impaired subjects, relative to those of the normal, were characterized by smaller dynamic range, poorer peak resolution, and poorer preservation of the vowel formant structure. These VMP characteristics, however, did not necessarily coincide with inaccurate vowel recognition. Vowel identification appeared to be related primarily to VMP peak frequencies rather than to relative peak amplitudes or between-peak characteristics of the patterns. [Work supported by NINCDS.]
Filtering competing messages to enhance mutual intelligibility
Authors: Corbett C. R. , Zurek P. M. , Durlach N. I. , Rabinowitz W. M.
Published: October 2005

Filtering simultaneous messages into different frequency bands prior to summation and presentation to a single ear was examined as an aid to message reception. Two or four concurrent sentences spoken by different talkers were presented through a single earphone to normal-hearing subjects. Listeners were instructed to write down the message spoken by the target talker, whose voice was indicated by an isolated lead-in message. In the reference condition, the wideband (0–4.5 kHz) sentences were simply summed; in various test conditions, the sentences were passed separately through different filters and then summed. Average intelligibility of the filtered sentences in the two-message task did not exceed that of the reference condition for any scheme tested. In the four-message task, however, performance improved significantly for three of five filtering configurations evaluated, the best of which resulted in 39% correct overall intelligibility compared to approximately 22% correct in the reference condition. Such a filtering scheme may be beneficial in future hearing aids that present multiple directional channels to a single ear. [Work supported by NIH.]