bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of vocalization behavior in a Madagascar amphibian
Authors: Narins Peter M. , Lewis Edwin R.
Published: July 2002

Vocalizations of Boophis madagascariensis (Rhacophoridae) males were recorded in a mid-elevation rain forest in eastern Madagascar. Call notes made by males of this species were classified into 28 types. This represents the largest known call repertoire of any amphibian. Even considering all iambic notes as variants of one type, there remain eight distinct call notes produced by this species. Morphological analysis of the vocal musculature of B. madagascariensis revealed no obvious adaptations for unusual glottal flexibility or function. Playback studies using a subset of the call notes as stimuli were carried out in the animals’ natural habitat to determine the functional significance of several of the call notes. One sequence of notes evoked increased call rates from males, other note sequences inhibited males from calling, whereas others appeared to have no effect on male calling rate. Call note pairs occurred inconsistently and unpredictably. The evolutionary significance of an extended vocal repertoire and a random call note production scheme are discussed. [Work supported by NIDCD Grant Nos. DC-00222 to PMN and DC-00112 to ERL.]
Shark and salmon movement measured by tracking radar-type acoustic transducers
Authors: Hedgepeth John , Fuhriman David , Johnson Robert , Geist David , Bartoo Norm , Holts David , Mulligan Tim , Cronkite George
Published: July 2002

Studies of fish behavior have used a methodology called the tracking transducer. The principle of tracking radar, aligning the antenna beam with a target, was applied with an acoustic split-beam transducer and dual-axis rotators for tracking individual fish over long periods of time. Deviation of the target from the beam axis produces a correction to point the axis toward the target. Initial studies with active acoustics have evolved an acoustic tag tracking method that is proposed for tracking both juvenile salmon and pelagic sharks. The major advance is that active and passive radar-type tracking can be combined in the same instrument. The tracking transducer was first used at Ice Harbor Dam, Snake River, 1995, and in 1996, at The Dalles Dam, Columbia River. Two tracking systems were used to triangulate a small acoustic transmitter in salmonid fish at Lower Granite Dam on the Snake River, Washington. Recently, adult salmon, returning to the Fraser River, were tracked to measure avoidance to surveying vessels. The feasibility for tracking sharks was shown at the Tacoma, Washington Point Defiance Aquarium. A proposed method of simultaneously tracking sharks with echoes and using acoustic tags will allow behavior, abundance, and associated pelagic assemblages to be determined.
Sound-signal scintillation approach to acoustic monitoring of the heat and mass transport through the Fram Strait
Authors: Naugolnykh Konstantin A. , Esipov Igor B. , Ovchinnikov Oleg B. , Tuzhilkin Yuri I. , Johannessen Ola M.
Published: July 2002

The computation model of the sound-signal propagation in the Fram Strait environment is considered in application to remote acoustic sensing of the heat and mass transport. A 3-D sound-speed environment has been simulated with respect to the statistical features of the real cross section of the strait obtained from experimental data. The linear four-element transmission array and four-element receiving arrray with equally spaced elements are modeled. Travel time variations of the signals propagating across the strait related to temperature change are calculated and the methods of the temperature retrieval in the complex environment is discussed. Then the travel time perturbations of the sound signals produced by the advection of the small-scale inhomogeneities across the path are considered. The calculation of the time-lagged cross-correlation function of the acoustic field gives the transverse current velocity data. By combining the response from each transmitter–receiver pair in different ways, the transverse current profile is retrieved. Results obtained are used to estimate the potential accuracy of the acoustic sensing of the heat and mass transport through the strait cross section. [Work supported by Environmental and Climate Programme of EC, Project PL970338.]
AMOC: Listen to the climate change?
Authors: Sagen Hanne , Johannessen Ola M.
Published: July 2002

Acoustical methods such as acoustic tomography and thermometry have proved their importance in future long-term monitoring of ocean climate. The scope of this presentation is to show how ambient noise can be used as additional information in a future acoustic monitoring system for the Arctic ocean. To our knowledge, no inversion of ambient noise characteristics to sea ice and ocean parameters has been attempted neither in the MIZ nor the interior of the Arctic Ocean. Key parameters in ocean climate monitoring in the Arctic are averaged ice thickness and averaged ocean temperature profiles. These parameters are very difficult and time demanding to measure by using point measurements, and unavailable using electromagnetic waves. Therefore, special attention has been paid to developing new concepts for measuring ocean stratification and averaged ice thickness. A new concept combining wave models, SAR data, and ambient noise recordings for retrieving the sea ice thickness and elastic parameters of the sea ice in MIZ are presented. Another concept is proposed for use in the MIZ and in the interior Arctic using averaged ambient noise frequency spectra to obtain information about the sea ice and ocean stratification.
Numerical modeling of high-intensity focused ultrasound for hemostatic applications
Authors: Khokhlova Vera A. , Kaczkowski Peter J. , Crum Lawrence A.
Published: July 2002

A promising therapeutic application of high-intensity focused ultrasound (HIFU) is hemostasis. In one possible hemostatic application, ultrasound induced heating will be used to stop bleeding during open surgery. To achieve substantial heat deposition on the surface of the bleeding organ, intense acoustic fields will be used, and therefore nonlinear effects on wave propagation in the coupling liquid between the transducer and the treated region must be taken into account. Moreover, nonlinearity can be used to increase the efficiency of heat deposition in shallow tissues by transforming wave energy to higher harmonics. Theoretical characterization of acoustic field is performed using a one-dimensional spherical wave model and the KZK equation. On-axis and off-axis waveforms, spatial distributions of harmonics, acoustic intensity, and heat deposition are calculated numerically in water and in tissue using a frequency-domain scheme. The influence of operating frequency, initial intensity, transducer aperture, amplitude shading, focal depth, and position of the water–tissue interface on acoustic propagation regimes and associated tissue heating is studied. For given absorption properties of the tissue and desirable spatial shape of the thermal lesion, an optimal set of transducer parameters and corresponding nonlinear effects are presented and discussed. [Work supported by DARPA, ONR, CRDF and RFBR.]
1-3 piezocomposite underwater transducers
Authors: Howarth Thomas R.
Published: July 2002

After over a decade of research (including application in medical ultrasonic products), 1-3 piezocomposite materials are now being utilized in a variety of U. S. Navy underwater transducer applications. This paper will survey a selection of current transducers that feature 1-3 piezocomposites as the active elements. The overview will chronologically present the transducers as they have evolved from the initial design of shaped aperture transceivers for acoustical environmental studies followed by a broadband projector for synthetic aperture sonars. Other transducers include cylindrical- and spherical-shaped constant beamwidth transducers (CBT), a parametric array, subbottom profilers, and acoustic calibration standards. An advanced design featuring an integrated accelerometer, acoustic pressure sensor, and actuation layer will be included. The 1-3 piezocomposite material attributes that are making these transducers useful for underwater applications will be discussed. The direction of future 1-3 piezocomposite-based underwater transducers will conclude the presentation. [This research was supported by the Office of Naval Research Code 333.]
Comparative study: Flow-induced noise on underwater acoustic pressure, particle velocity, and intensity sensors
Authors: McConnell James A. , Lauchle Gerald C.
Published: July 2002

A neutrally buoyant underwater acoustic p-u intensity probe contains discrete sensors for direct measurement of acoustic pressure and particle velocity [J. A. McConnell and G. C. Lauchle, J. Acoust. Soc. Am. 103, 2755(A) (1998)]. Intensity is calculated from the cross spectrum between these two quantities. Thus a single probe can be categorized as a compound sensor capable of independently measuring acoustic pressure, particle velocity, and intensity. Using this probe, a comparative study concerning the measurement of all three quantities in the presence of mean flow and an independent sound source was performed. Bias errors, which result from the flow-induced noise generated by towing the sensor (e.g., a cylindrical body) in cross flow at low speeds through a channel of water, are presented. Other parameters of interest include analysis of experimental pressure–pressure and pressure–velocity correlation functions. The effect of body geometry (e.g., variation in aspect ratio) on the measured bias errors and correlation functions is also presented. [Work supported by the Office of Naval Research, the Naval Submarine League, and the Acoustics Technology Branch of the Naval Air Warfare Center—Aircraft Division, via the DoD Small Business Innovation Research Program.]
Bias error due to flow-induced noise on a velocity gradient underwater acoustic intensity sensor
Authors: Bastyr Kevin J. , Lauchle Gerald C.
Published: July 2002

A neutrally buoyant underwater acoustic u-u intensity probe employs discrete sensors for the direct measurement of acoustic particle velocity at two locations. Active intensity is calculated from the cross spectrum between the two velocity sensors [K. J. Bastyr and G. C. Lauchle, J. Acoust. Soc. Am. 103, 2755(A) (1998)]. Under quiescent conditions the sensor has no bias error; however, in the presence of mean flow, this is no longer true. A derivation of the bias error that results from performing acoustic intensity measurements in the presence of mean flow is presented. Results show that the bias error due to the turbulent boundary layer generated by fluid flow over the cylindrical body that encapsulates the sensors is proportional to the cross spectrum of the turbulent velocities measured by the sensors. This theoretical derivation is quantified with preliminary experimental data obtained by towing the sensor at low speeds through an open channel of water. [Work supported by Office of Naval Research, Multi-University Research Initiative on Acoustic Transduction, Materials, and Devices.]
Development and testing of an ultrasonic PMN transducer
Authors: Coutte Jocelyne , Granger Christian , Dubus Bertrand , Debus Jean-Claude
Published: July 2002

Lead magnesium niobate ceramics (PMN) are promising materials for realizing high-power transducers for macrosonics or underwater acoustics because of the large strains at moderate electric field and the low hysteresis. The use of PMN ceramics in transducers presents some difficulties: highly nonlinear properties, temperature and frequency dependence of dielectric permittivity, and dc bias field needed. This paper describes the design, realization, and testing of a 20-kHz transducer. The Langevin-type transducer is made of four PMN-PT rings prestressed by a steel bolt between two-end-masses. The transducer is modeled using electrostrictive finite elements [J. C. Debus et al., J. Acoust. Soc. Am. 103, 3336–3343 (1998)]. It is optimized in terms of coupling coefficient and radiated acoustic power for in-air or in-water applications. The transducer is tested for several temperatures and various bias voltages and prestresses. Resonance and antiresonance frequencies, coupling coefficients, and vibrational amplitudes are measured and compared to numerical predictions and to experimental results on a reference piezoelectric transducer. [Work supported by a DRET/DCN grant.]
Web-accessible resources for teaching phonetics
Authors: Eriksson Anders
Published: July 2002

The paper covers two aspects of the usability of the Internet resources in teaching phonetics. First of all, the Internet may be used to disseminate information and teaching materials. Search facilities provided by normal, search engines are too coarse, however, to be really useful if one wants to find suitable teaching resources (course notes, tutorials etc.). One way to address this problem is to use a structured inventory of hyper-links to relevant materials. A working group within the Socrates/Erasmus thematic network on Speech Communication has set up a searchable inventory of web accessible materials, relevant to teaching phonetics. The principles underlying the structuring of the database will be described and illustrated by examples from the database. A second possible use has to do with Open and Distance Learning (ODL). Phonetics, however, requires both sounds and images to be realistic, and for many areas the possibility to perform experiments is essential. With the advent of internet-based tools like audio and video players and programming languages like Java new possibilities have opened up for realistic, high-quality phonetics resources. The presentation will demonstrate a perception test, which may be run inside a normal web browser and which is accessible over the Internet.
Model of the human speech production based on vocoder techniques
Authors: Fellbaum Klaus , Richter Joerg
Published: July 2002

A tutorial is presented with which the student first gets basic knowledge about the human speech production. It is explained that speech is generated by an air flow coming from the lungs which is, in the case of voiced sounds, periodically interrupted by the vocal cords and then modulated with the resonance rooms of the mouth and nasal tract. For voiceless sounds (like ‘‘f,’’ ‘‘sch’’) the vocal cords are open and the air flow excites the mouth and nasal tract with a noise-like pressure signal. It is therefore adequate to distinguish two components in the speech production: the excitation and the articulation component. In our tutorial, the two components are realized (simulated) by a technical system, known as linear predictive vocoder (LPC vocoder). Its principle is explained by a short text and some graphics and the analogy to the human speech organs is clearly shown. The main emphasis is put on the control parameters of the system—in the main the pitch frequency and the vocal tract parameters (prediction coefficients)—and the effect when.
Numerical simulation of timpani
Authors: Joly Patrick , Rhaouti Leïla , Chaigne Antoine
Published: July 2002

The goal of this work is to achieve sound synthesis via time-domain numerical simulations, with particular interest in the case of timpani. The approach combines the use of a mathematical model, which is supposed to represent accurately the physics of the phenomena, and of modern techniques for the approximation of partial differential equations. The model appears as a system of wavelike equations coupled by fluid–solid interaction conditions. It includes various damping mechanisms as well as a nonlinear model for the mallet–membrane interaction. The numerical approach aims at realizing the best compromise among accuracy, stability, and efficiency. Its main characteristics are the use of finite elements for the space discretization, of a fictitious domain method for a flexible treatment of the geometry of the instrument, and of explicit centered finite differences for the time discretization. Higher-order absorbing boundary conditions are used for simulating the radiation of sound in free space. In the presentation, the main properties of the numerical methods will be emphasized and various numerical results will be compared to experiments.
Investigating the effect of different strutting arrangements on the modes of a guitar soundboard
Authors: Lewney Mark , Richardson Bernard E.
Published: July 2002

A spruce soundboard was fitted with a bridge and attached to an experimental rig which provided a fixed edge and uniform backing cavity volume. The rig allowed the same soundboard to be fitted with various standard strutting arrangements. The mode shapes and frequencies were investigated using holographic interferometry. Of particular interest were the small changes in mode shapes induced by the different strutting arrangements. Input admittance measurements were made to determine the effective mass of each mode as ‘‘seen’’ by the strings. Previous psychoacoustical work [H. A. K. Wright, Proc. Inst. Acoust. 19(5), 149–154 (1997)] has suggested that effective mass is an important parameter in determining a mode’s contribution to the overall sound output, and can be significantly affected by small changes in the mode shape. A new method of determining the effective mass is also presented. [Work supported by EPSRC.]
Finite-element analysis of vibrating trombone bell
Authors: Hoekje P. L. , Morrison Andrew
Published: July 2002

Finite-element analysis (FEA) was used to predict the vibration patterns of an isolated trombone bell. These vibrations are implicated in subtle contributions to the sound field, over and above the primary contribution from the vibrating air column. Holographic interferometry of vibration patterns of an actual bell reveal that most modes exhibit rotational symmetry with vibrating patches of equal size distributed around circumferential rings. Such modes at low frequencies will radiate poorly. However, some patterns observed by holography do not display such symmetry and will have enhanced sound radiation as a result. FEA calculations using a mesh of points with rotational symmetry seem to give only symmetric modes, but lead to elements of unequal sizes and aspect ratios. On the other hand, using the package’s AutoMesh feature to redraw the mesh into equal-sized elements for more efficient computation introduces inherent asymmetries into the model, and also breaks the symmetry of the solutions. It is concluded that the observed asymmetries in the holographic data are due to asymmetries in the bell itself, leading to enhanced radiation of sound. [Work supported by the Carver Foundation.]
Noise levels in dental practice
Authors: Domitrovic Hrvoje , Bagic Ivana , Ivancevic Bojan
Published: July 2002

Noise can cause unwanted masking of sounds, interference with speech, even pain and injury, and temporary or permanent loss of hearing. Concerning exposure of noise levels at the workplace, industrial plants and huge machines are usually considered. However, there are ‘‘clean’’ jobs where people are exposed to significant noise. One example, which will be treated in this paper, is dental practice. In this work it is intended to show the results of SPL measurements that were done at the Dept. of Pedodontics in the School of Dental Medicine Zagreb. One- and two-channel measurements were made using a sound level meter and an artificial head (head-and-torso simulator). Noise levels generated by various dental devices, their spectra, and differences between noise levels in left and right ear (in the dentist’s usual working position) were shown. The sound power and subjective sound levels regarding sound source frequency and intensity were determined upon results of these measurements. Special attention was paid to ultrasound and infrasound components, as well as vibrations. Since two Faculty practices with a dozen of dental sets in each were at our disposal, influence of aging and wearing, particularly in mechanical devices, was also considered.
Amplitude-sensitive attenuating earplugs
Authors: Hamery Pascal J. F. , Dancer Armand L.
Published: July 2002

The most simple amplitude-sensitive attenuating earplug is made of a plate with one little hole that is inserted in a perforated plug (like Racal Gunfender). That hole presents an acoustic impedance which has essentially a viscous resistance and a nonlinear dependence on the particle velocity in its center [L. J. Sivian, J. Acoust. Soc. Am. 7, 94–101 (1935); U. Ingard and H. Ising, ibid. 42, 6–17 (1967)]. The dimensions of that hole have been optimized and a new configuration, i.e., an empty cavity with two perforated plates, has been designed. This ‘‘filter’’ of small dimensions can easily be fitted into different commercial perforated earplugs. To better understand the experimental results and optimize the acoustic nonlinear ‘‘filter’’ dimensions, a theoretical model has been developed. Moreover, an experimental setup is described which allows visualizing the particle velocity inside the cavity with a particle imagery velocity camera which helps to understand the actual behavior of such a nonlinear cavity.
The effects of ultrasonic waves on dye penetration with cellulose fabrics dyed by vinylsulphonic dyes
Authors: Ignjatovič Vesna , Novakovič Mile , Miljkovič Milena
Published: July 2002

Research has shown that ultrasound traveling in the form of waves through liquids causes the effect of cavitation. Cavitation is manifested in a continuous creation and disappearance of vacuums within the liquid. Therefore, interruptions are created in the liquid, that is, strong forcing waves are made. The cavitation strikes are used in solid matter destruction, emulsion creation, greasy surface cleansing, and the like. The ultrasonic energy has been applied in textile industry, for the most part in soaking processes, and textile washing and cleaning. There is research indicating that ultrasonic energy can be used in dyeing of cotton with direct and reactive dyes, of polyamid and wool with acid dyes, and of polyester and acetate fibers with disperse dyes. Based on previous research, this paper is an account of an experiment whose aim was to implement the latest achievements in vibration and ultrasonic theory in textile dyeing technologies. Thus cotton knitwear has been dyed with vinylsulphonic reactive dye, with and without the use of ultrasonic energy, and with the introduction of an air bubble in the dye tub with the application of ultrasonic energy. Previous experiments have shown that ultrasound contributes to greater dye absorption from the tub, so that equal distribution dyeing with the use of ultrasound requires less dye, shorter period of dyeing, less power consumption, and at the same time the pollution of waste waters is reduced. All these characteristics make this procedure economically and ecologically affordable. So as to intensify the process, this research has been directed towards the introduction of an air bubble in the dyeing tub which is under the effect of ultrasound. Dye absorption from the tub and dye penetration in the fabric have been monitored by means of spectrophotometry (absorption and reflection spectrophotometry). Previous research projects have not been able to explain completely the fundamental interaction of ultrasound and fibers, that is, reactive dyes in water, and with that, in the process of dyeing itself. Therefore, future work will deal with this problem. [This paper is a part of research done for the requirements of the project titled ‘‘Modern Approaches in New Dyeing Procedure Development for Optimal Pollution of the Environment,’’ and financed by Science and Technology Ministry of Serbia.]
The effects of ultrasonic energy on reactive dye absorption in the presence of reduced quantities of salt
Authors: Novakovič Mile , Ignjatovič Vesna , Miljkovič Milena
Published: July 2002

Ultrasonic energy has shown a wide range of application possibilities in many fields of human craftsmanship, and its application in textile industry has been a matter of research for a number of years. For the time being, the best results have been achieved in other research still being done in laboratories. This paper presents a part of the overall research done within the project ‘‘Modern Approaches in New Dyeing Procedure Development for Optimal Pollution of the Environment,’’ financed by Science and Technology Ministry of Serbia. One of the predetermined objectives of the project is to examine the possibility of ultrasonic energy application in technological processes of dyeing cellulose fabrics by vinylsulphonic dyes. Having that in mind, it is necessary to systematically investigate all of the aspects of ultrasonic energy effects on textile substrata, the dye, and the relation of dye solution and fiber. In the experiments, cellulose microfiber knitwear has been dyed with vinylsulphonic dyes according to the on-line procedure, at a stable temperature, with the addition of varying quantities of salt. Concerning the fact that salt has the ability of enhancing dye absorption from the tub, and that ultrasonic energy helps the process of absorption, the quantity of salt required may be reduced, and thus reduce the cost of dyeing and the pollution of waste waters. Dye absorption from the tub has been monitored by means of absorption spectrophotometry. With the method of reflection spectrophotometry, spectral remission curves have been measured, K/S values calculated, and respectively the relative intensity of dyeing on the fabric determined.
Evaluation of a physiological ear model for the simulation of nonlinear masking effects
Authors: Baumgarte Frank
Published: July 2002

A physiological model of the human auditory system with the aim at generating masked thresholds for arbitrary sound signals was presented at the previous DEGA meeting. The main parts of the ear model are an active nonlinear cochlear model and a threshold detector which evaluates changes in specific loudness. It was shown that the ear model is able to rebuild the level dependency of spectral and temporal masking patterns, the asymmetry of masking between noise and tone, and the different detection thresholds for amplitude and frequency modulation. This study presents new simulation results for nonlinear masking effects. These results indicate that the nonlinear ear model allows demonstration of other nonlinear psychoacoustical effects such as the additivity of masking, suppression, and distortion product detection. Since the physiological ear model represents a unified approach covering the most important masking effects of arbitrary sounds, it is suitable for applications such as perceptual audio coding. An improved coding efficiency is expected due to the more accurate masked thresholds generated by the ear model in comparison to results from psychoacoustical models commonly used in audio coding which neglect many of the nonlinear effects of auditory perception. [Work supported by DFG.]
Detection of tones of unexpected frequency in amplitude-modulated noise
Authors: Fitzgerald Matthew B. , Wright Beverly A.
Published: July 2002

The percentage of correct detections of tonal signals presented in wideband sinusoidally amplitude modulated (SAM) noise, or noise with SAM and unmodulated regions, was measured for an expected signal of 1000 Hz and unexpected signals of 200, 600, 1400, and 1800 Hz. The level of each signal was set so the signal could be detected on 85% of trials when presented by itself. When the noise was 100% SAM at 10 Hz, six of nine listeners detected at least one unexpected signal on over 70% of trials. When a 400-Hz wide region centered at 1000 Hz was unmodulated and the remaining wideband noise was SAM, or vice versa, all three listeners still detected at least one unexpected signal on over 70% of trials. With unmodulated noise, all unexpected signals were detected at chance. These results suggest most listeners monitor multiple auditory filters when detecting tonal signals in noise that is entirely or partially SAM. This listening strategy may be related to, but not responsible for, the better detectability of signals in wideband SAM than unmodulated noise, because here signal levels in SAM noise were similarly low for listeners who did or did not detect unexpected signals. [Work supported by NIH/NIDCD.]
Source localization on a ‘‘fuzzy structure’’ beam using matched-field processing
Authors: Feit David , Craun Matthew
Published: July 2002

Matched-field processing (MFP), a technique originally developed by the underwater acoustic community [Baggeroer, Kuperman, and Mikhalevsky, IEEE J. Ocean Eng. 18, 401–424 (1993)] for source localization, is used to localize the source of excitation on a flexurally vibrating beam to which is attached a ‘‘fuzzy structure (FS).’’ The FS, for this study, consists of a set of flexurally vibrating strips, of randomly varying lengths, attached at uniformly spaced points along the length of the beam. MFP differs from classical inverse methods in that it does not require an inversion of the system model. Instead it correlates or ‘‘matches’’ observed signals with solutions of the equations of motion for a range of excitation points using a variety of linear and nonlinear methods. In this paper several different MFP algorithms are used and compared where the observed or simulated data is measured both globally, along the entire length of the beam, or locally over a limited region of the structure. Successful localization is found to be dependent on frequency. For lightly damped structures, the MFP localization results become ambiguous at the resonance frequencies of the structure. [Work supported by ILIR Program CDNSWC.]
High spatially sampled interior acoustic measurements of a turboprop aircraft for near-field acoustic holography (NAH) algorithm development
Authors: Herdic Peter C. , Houston Brian H. , Williams Earl G.
Published: July 2002

Experimental results are reported of in-flight acoustic responses acquired by scanning a dense array of microphones within an aircraft interior. High data quality was obtained in several measurement sets. This database will ultimately be used for inverse and forward projections of the measured, enclosed acoustic surface to determine the velocity of the fuselage skin and the entire interior acoustic field. A discussion of the experimental design methodology will include approaches to measure the in-flight pressure field coherently during the execution of a scan, spatial sampling requirements based on measured vibration over an arc of the fuselage wall, and the effect of ambient noise on the measurement. The in-flight acoustic response shows spatial variation throughout the interior with dominant blade passage harmonics. Two ground-based (engine off) measurement scans were performed where excitation by an internal acoustic source and a point force applied to a frame assist in identification of interior acoustic modes and structural resonances. [Work supported by NASA, Langley.] a)Also SFA, Inc.
A text-to-speech oriented comparison of English and Polish intonation
Authors: Demenko G. , Jassem W.
Published: July 2002

Current analyses of Polish intonation in terms of F0 tracings indicate that it is possible to represent the melodies in the two languages within one descriptive framework, much as in the ‘‘British’’ tradition. The basic structure of an intonation phrase can be represented as ([([wPT])+[sPT])+[NT (+NT)], where NT is the nuclear tune, sPT is the strong (accented) prenuclear tune, and wPT is the weak (unaccented) prenuclear tune. A monosyllabic sPT and a monosyllabic NT are accented, as is the first syllable of a sPT or NT of more than one syllable. The chief structural difference between E and P is that P allows mononuclear intonation phrases only, while E has a special case of a binuclear IP. If rise-fall-rise in NT position can be shown to be an independent NT in E, then this NT does not exist in P. Most of the tunes have quite similar realizations at the phonetic level. The widest differences between E and P with respect to intonation are obtained in their semantic/pragmatic meanings and in the occurrence frequencies. F0 traces have confirmed the linguistic structure of an intonation phrase. The importance of dynamic parameters, i.e. those which describe the relations in the adjacent vowels/syllables describing the set of intonation structures under investigation, was tested by means of neural networks.
Vocal-tract parameter estimation from formant patterns
Authors: Freienstein Heiko , Müller Knut , Strube Hans Werner
Published: July 2002

A method is proposed to estimate individual vocal-tract parameters from formant frequency patterns. Vocal-tract parameters, such as scaling factors of vocal-tract length and area were determined in reference to the given area function of an articulatory synthesizer. These individual parameters of various speakers are expected to be suitable to normalize speakers in automatic speech recognition. It has been shown by Schroeder (1967) that there is a linear relationship between relative formant frequency deviation δω/ω and a relative area perturbation δA/A of the area function. Further, a similar relationship can be derived for length perturbation of an area function. The presented method is based on the inverse relationship: deviations of the formant frequency pattern of a speaker relative to the reference speaker are attributed to length and area perturbations of the area function of the reference speaker. A pilot study using synthetic speech showed promising results: estimated vocal-tract area functions were in good agreement with natural area functions. In the present study the method is extended to real speech. Investigations are carried out on speech samples of a German data base (PhonDat) to find speaker-specific parameters. [Work supported by Deutsche Forschungsgemeinschaft (Str 255/7-2).]
Blueprint of a biomechanical model of vocal tract structures
Authors: Wilhelms-Tricarico F. Reiner
Published: July 2002

A new biomechanical model of the vocal tract is under construction. Structures of the tract will be represented in a three-dimensional finite-element model. In contrast to a previous pilot project [see Wilhelms–Tricarico, J. Acoust. Soc. Am. 97, 3085–3098 (1995)], this model will make use of tri-quadratic finite elements and uses implicit time stepping methods. The new model comprises the entire oral floor and the tongue as a system consisting of a small number of finite elements. It will incorporate modeling of collision and sliding between the tongue and the teeth and the hard palate, as well as a moving mandible and hyoid bone. Algorithmic and implementation details will be presented.
Auditory perception of rolling balls
Authors: Houben Mark , Franssen Luuk , Hermes Dik , Kohlrausch Armin , Eggen Berry
Published: July 2002

Two experiments investigating the perception of recorded sounds of rolling wooden balls are reported. In the first experiment, whether subjects can identify differences in the size of rolling wooden balls, is studied. In the second experiment, the velocity of rolling balls is varied. Real recordings of wooden balls rolling over a wooden plate were presented pairwise, with a 700-ms pause in between. The stimuli had a duration of 800 ms and were presented at equal SPL. Subjects had to decide which of the two sound examples was created by the larger (first experiment) or faster ball (second experiment) (2I2AFC procedure). The results of the first experiment show that subjects are able to identify differences in the size of rolling balls, except for the stimulus pair with the smallest relative difference in diameter of 14%. The second experiment reveals that most subjects can clearly discriminate between rolling balls with different velocities, if the relative difference exceeds about 30%. However, some subjects had difficulties in labeling the sounds correctly, resulting in percentage correct responses close to 0%. It is to be expected that labeling errors will disappear when subjects receive feedback about the correctness of their responses.
Recent multi-purpose hall designs in Denmark with physically variable acoustics
Authors: Gade Anders Chr. , Jordan Niels Vilhelm
Published: July 2002

This paper describes two recent Danish multi-purpose hall designs, in which acoustic variability has been accomplished in different ways: through variable absorption and variable volume, respectively. The different approaches were chosen in order to insure that not only reverberation time (T) and so clarity (C), but also the strength parameter (G) could be varied in a favorable direction in view of the prescribed uses of the halls. The hall with variable absorption is the assembly hall in the new extension to the Royal Library in Copenhagen to open in fall 1999. This hall will seat 600 people and be used for chamber music concerts, symphony orchestra rehearsals, and amplified speech. For the latter two functions, a reduction in G along with reduction in T was considered favorable. The hall with variable volume is the recently opened Esbjerg Musikhus seating 1100 and equipped with a full stage house. This hall is used for symphonic concerts and musicals as well as drama and conferences. In this hall, maintaining or even increasing G along with a reduction in T is advantageous, especially in the drama theatre mode. The paper will describe the design of these two halls along with acoustic measurement results.
Acoustical design of the Walt Disney Concert Hall in Los Angeles
Authors: Toyota Yasuhisa
Published: July 2002

A completely new concert hall is scheduled to be opened in the downtown of Los Angeles. The hall was named the Walt Disney Concert Hall, after the late Walt Disney, since the project was started based on the donation of 50 million dollars by Mrs. Disney. The hall was designed as a monopurpose concert hall mainly for orchestral music and is scheduled to be a home hall of the Los Angeles Philharmonic Orchestra and Esa-Pekka Slonen, the Music Director of the orchestra. The hall has approximately 2400 seats and widely spread seating arrangements around the stage like the Berlin Philharmonic hall and the Suntory Hall in Tokyo. Computer simulation studies were carried out to determine the room shape, and acoustic tests with 1/10 scale model were introduced in the final process of the design stage. Construction work is scheduled to start in March 1999, and be completed in 2002. Acoustical design of the hall, especially on its room acoustics and the results of the 1/10 scale model tests, will be reported.
Prediction of noise in workrooms including extended sources, directivity of radiation, and screening
Authors: Probst W.
Published: July 2002

For many years the mirror image method has been used to calculate noise levels in workrooms. Fittings are taken into account by a fitting density defined by Kuttruff and extended to this application by Jovicic. In a research program financed by BAUA Dortmund it was examined how directivity of radiation and screening can be integrated. A removable screen was installed in different halls and it measured the sound distribution in the shadow region, which was produced by a uniformly radiating loudspeaker radiating white noise. Calculation of the same situation by taking into account screening showed that only low orders of reflection are influenced by the screen. This gives the necessary information for a modification of software programs to include screening. Similar to this procedure, a loudspeaker with high directivity was used as source with known emission to measure sound decay curves in workrooms. The same situation was calculated by mirroring the complete directivity of the source. Measured and calculated levels are in good agreement. With these techniques the German standard VDI 3760 for noise calculation in rooms can be improved in the next years.
Modeling of noise in factory workrooms—A practical perspective
Authors: Lewis David N.
Published: July 2002

It has been known for a considerable time that classical diffuse field theory cannot be applied to workrooms where either of the floor dimensions are greater than approximately five times the ceiling height [H. J. Sabine, Proc. Third Annual Noise Abatement Symposium, Vol. 3, 10 October (1952)]. In such large workrooms there are often many sources of noise and the benefits of alternative noise control stategies are often not obvious. Computerized methods of noise prediction in factory workrooms were first developed in Unilever around 1979. The first major application and validation of the technique was on a project to reduce noise in a manufacturing facility in 1980. The main tool for noise prediction is an in-house package which calculates the combined effect of multiple sources at all points 1 m apart within the building. Source sound power, directivity, and the propagation curves for the building are input, the latter having been derived from ray tracing predictions, empirical models, or measurement. The technique has been used successfully on numerous projects in the last 20 years and is a valued tool for illustrating the likely benefits of acoustic treatment or defining noise control specifications. An overview of the technique and its application is presented.
An adaptive beam tracing method for room acoustics prediction
Authors: Lam Yiu W. , Drumm Ian
Published: July 2002

A new adaptive beam-tracing algorithm was developed and implemented into a computer model to predict the propagation of sound in enclosed spaces. Unlike previous beam-tracing methods, the model predicts a near perfect geometrical representation of a propagating sound field by adaptively tailoring it to the shape of the reflecting surfaces. Using this adaptive approach, problems such as gaps and overlaps between beams, and the ambiguity of reflection direction when a beam hits more than one surface can be eliminated. In addition, the beam tracing can start with only a small number of beams. Child beams are generated automatically upon each reflection to adapt to the complexity of the room. This method runs faster than traditional beam and ray-tracing methods in the early part and faster than the image method in the later part of the reverberation process. Diffuse reflections are handled by a radiant exchange process and combined with the specular reflections to calculate the impulse response of a room. This model is applied to several spaces with representative workspace shapes and fittings and the result is compared with traditional prediction methods. The suitability of using diffuse reflections to model the effect of factory fittings is investigated.
Call center as an acoustical challenge
Authors: Voelker Ernst Joachim , Fischer Sabine
Published: July 2002

Call centers differ from the standard open plan offices in that telephone calls using headsets lead to special types of activities at the working places. Phone calls with clients produce almost simultaneously an A-weighted speech-noise level of around 52–58 dB when, for instance, 12 or 18 neighboring working places are occupied. On the other hand, the background noise produced by all persons working is much lower at around 43–45 dB in well-known open plan offices when quiet work (such as paperwork) is being performed, or when employees are absent. In both cases, there are certain levels of privacy expected. Call centers belong to grade three privacy with a permitted signal-to-noise ratio of around 9 dB. Many room acoustical properties must be considered, such as the falling off of sound levels with increasing distances, avoidance of disturbing sound reflections, short reverberation times, and well-designed sound barriers which must have a soundproofing quality and a high sound absorption. Measurements in existing call centers can be related to the grades of privacy within a certain field of confidence. The same applies to other open plan offices. Artificial background noise such as sound conditioning must be introduced in order to reach the privacy accommodations.
Use of the Zwicker method to predict signal audibility in noise with hearing protection devices
Authors: Liedtke Martin
Published: July 2002

Hearing protection devices (HPDs) can decrease perception of acoustic warning signals. Therefore, specific restrictions are given for the use of HPDs in specific danger areas in Germany. For example, up until 1996, German traffic regulation did not permit use of HPDs while steering a vehicle in road traffic. Within investigations carried out in the 1980s, the audibility of track-layer warning signals was examined during exposure to typical noises and when HPDs were worn. For this purpose, differences in audibility were determined on the basis of the Zwicker method (ISO 532, Method B). As a result, a procedure to predict signal audibility with HPDs was available to select appropriate HPDs for specific situations at work. A special procedure to be carried out if HPDs have to be worn in road traffic was published in 1996 in Germany: A list of hearing protectors realizes a preselection; a final perception test at work under operation conditions carried out by the individual employee and the person responsible for safety indicates the suitability of the HPD. Recent investigations on level-dependent HPDs show that the level of signal audibility seems to depend on the transfer characteristic of the level-dependent HPD.
Assessing changes in the noise environment from military training ranges: A case study in forensic acoustics
Authors: Luz George A. , Lewis Nelson D.
Published: July 2002

In response to litigation alleging that an Army installation was making more noise in land adjoining tank and artillery ranges in 1997 than when the owner had purchased the land in 1969, the past weapons noise environment had to be reconstructed from available data. The results, which documented the changes in the training noise environment from 1971 to 1984 to 1997, demonstrated the long-term benefits of the U.S. Army Construction Engineering Research Laboratories’ bnoise computer model. Also discussed is (1) the use of automated noise monitoring data to validate ‘‘busy day’’ weapons noise contour maps and (2) the potential for cost savings by combining environmental noise modeling with air, water, and solid waste pollution.
Experimental investigations of surface pressure fluctuations related to car interior noise
Authors: Brähler B. , Borchers I. U. , Schauwecker L. , Mellert V.
Published: July 2002

Due to the progress in the reduction of engine noise and tire/road noise for cars, aerodynamically induced noise becomes increasingly important for car interiors and for speeds above 120 km/h. The aerodynamically induced noise is mainly caused by flow separations which may lead to highly intensive surface pressure fluctuations forcing the car housing to vibrate and to radiate. This is the case especially for the windows, which have a relatively small transmission loss. Due to the very strong flow separations behind both the A pillar and the rearview mirror the side windows play a major role as aeroacoustic noise sources in the interior of automobiles. In this study the flow around the side windows of a production car, where there is nearly no vortex separation on the A pillar, is investigated. Therefore, the influences of the A pillar and rearview mirror could be studied independently by generating each source separately. For different configurations measurements of the hydrodynamic pressure fluctuations next to the side window were performed. Dependent on the spatial distribution of the pressure fluctuations significant changes for the car interior noise may be expected. The experimental results suggest a large potential of further reduction of car interior noise due to an aeroacoustic optimization of the flow.