bluuebunny/crossref_metadata_2025 huggingface dataset:
Parsing complex rhythmic structures: The contribution of spectral and temporal dimensions of timbre
Authors: Singh Punita G.
Published: July 2002

Perceptual parsing of sequences with multiple possible metric interpretations was studied. Sequences of 12 complex tones were used as stimuli, with either no deliberate accents provided, or physical accents introduced by changing timbre at positions implying a triple, quadruple, or multiple meter (i.e., both triple and quadruple simultaneously). Subjects reported if they perceived a triple meter, quadruple meter, ambiguous meter, or no meter. The number of harmonics (2, 4, or 8) or the locus of three harmonics were the spectral variables used to mark timbre accents. Steepness of rise and decay time (95+5 ms versus 5+95 ms) was the temporal variable used. These attributes served well as accent markers for sequences with unambiguous meters. However, listeners were generally unable to parse sequences where multiple meters were provided by the same timbre cue. For sequences where multiple meters were provided by contrasting timbres, listeners generally picked the metrical structure implied by spectrally richer or brighter timbres comprising more or higher harmonics. Temporal envelope slope was not effective in facilitating parsing of meters.
A review of recent military aviation noise programs
Authors: Stusnick Eric
Published: July 2002

This presentation reviews recent studies that have been carried out by Wyle Laboratories on noise from military aircraft operations. Four different areas of research will be described—modeling, measurements, psychoacoustics, and noise control. The discussion of subsonic aircraft noise models includes NOISEMAP, ROUTEMAP, MR—NMAP, and the Rotorcraft Noise Model, while that of supersonic noise models includes CORBOOM, BOOMAP3, and PCBOOM. The discussion of aircraft noise measurements includes sonic boom monitoring, military training route measurements, NOISENET, potential damage to unconventional structures by sonic boom, and rotorcraft noise measurements. The psychoacoustic discussion includes the development of the onset rate correction for high-speed, low-flying military jet overflights and community response to sonic booms. The discussion of aircraft noise control will describe the use of active noise control to reduce noise from hush houses and static jet engine runups.
The theoretical and practical aspects of producing source data for helicopter noise modeling
Authors: Weston R. J. , Beaman R.
Published: July 2002

Accurate source data are the key to future developments in noise modeling. With the increasing need to model helicopter noise, suitable source data will be required. For helicopters, the directivity of the noise source is an essential component of the model. This paper reviews a system for determining helicopter directivity together with a discussion of future developments. An overview of an international helicopter noise measurement trial conducted in June 1998 to determine directivity will be presented along with some of the data.
The perception of product sound quality
Authors: Jekosch Ute
Published: July 2002

There are different methods and methodologies available to assess the quality of sounds. Generally, instrumental and auditory assessment can be distinguished. For instrumental assessment, physical data are collected and analyzed, and a sound quality value is computed in the end. Auditory assessment methods use human listeners who judge on the quality of a perceived sound. Experts very often face the fact that instrumental and auditory quality values are not in accordance with each other. This holds especially for the case where instrumental methods are used to predict how a human listener will perceive the quality of a sound. It is the task of sound quality assessment research to abridge the gap between predicted and experienced sound quality. There are different approaches to reach this goal. The talk concentrates on one specific aspect, namely on the function of sounds. Sounds convey a meaning. The meaning is assigned to them by the listener. The relation between form and content is either arbitrary or fixed. Instrumental and auditory sound quality assessment have to consider these aspects: An appropriate assessment of sound quality has to include the aspects of the acoustic/auditory form, the listener, and the meaning he/she assigns to the auditory event.
Adequacy of product sound: Design–develop test; is it so simple?
Authors: Schallig Michiel A. A.
Published: July 2002

Philips DAP B.V. is a major producer of consumer household appliances. Electric shavers and vacuum cleaners are examples of the products that are produced. Consumer satisfaction is of paramount importance for the company. This is obvious for the functional aspects of the appliance, but satisfaction goes beyond functionality. Design, price, ergonomics, and sound are a few aspects which can contribute to the desired level of satisfaction. To achieve this delicate balance within such different constraints is a difficult process. Control of the sound production of appliances is something that has to be tackled from the start of the development, but becomes increasingly difficult. Especially ‘‘softer’’ constraints like ‘‘sound quality’’ blurr the development process. Despite the difficulties, these softer aspects are considered more and more important. In the real development processes, however, it is, for example, very difficult to get good measurement data of human perception. Often this is done by panel research, but this is a very slow process and depends heavily on the availability of the correct panels. This is one of the many problem aspects that are related to developing appliances with a ‘‘quality sound.’’ Some real world experiences, observations, and problems on the road to adequate sounds are described.
Exploration of associated imaginations on sound perception (AISP): A method for helping people to describe and to evaluate their sound perceptions
Authors: Muckel Petra , Ensel Leo , Schulte-Fortkamp Brigitte
Published: July 2002

A qualitative method especially developed for helping people to describe and evaluate their sound perceptions will be presented: The development of this method for ‘‘Exploration of Associated Imaginations on Sound Perception’’ (AISP) took place in a project about interior car sounds and possesses relationships with CIS (categorical scaling intermittent and subsequent thinking aloud) by Schulte-Fortkamp. Its starting points are the subjects’ spontaneous imaginations and memories when they are going to listen. Focused on the effects of sounds, the design of AISP encourages people to describe their perception of sounds by telling their spontaneous associations, e.g., imaginations, memories, and embedded sensations and feelings in their own words and fashion. In an interview aided by a questionnaire, the subject evaluates sounds in leading his/her attention to his/her own imaginations, memories, and feelings while listening. These imaginations function as a context and biographical background for the subject’s feelings; they make it easier to find words for the description of the sound perception, especially for the emotional effects of sounds. The purpose is to learn about descriptions of sounds and their possible emotional effects by associated imaginations and feelings.
Urban noise survey for the city of Porto Alegre, Brazil
Authors: Sattler Miguel A.
Published: July 2002

This paper presents the methods and results of a simplified traffic noise survey for the city of Porto Alegre, the southmost capital city in Brazil. Noise measurement data and hourly vehicle flow data were used. Both were obtained at 6 p.m. Values from 560 sites were considered, making possible the construction of a simplified traffic noise map, built upon Leq values. The work, which tries to identify, for the stated time, the impact of noise on the population, in terms of the magnitude of the population exposed to different noise levels, has shown that 90% of the population included in the sample is exposed to A-weighted noise levels exceeding 65 dB.
Models for acoustic sources in urban areas
Authors: Gaulin David , Bérengier Michel
Published: July 2002

Due to the large increase of populations in urban areas and the impact of sound phenomena on their life, the control of noise in cities is now of great importance. To predict acoustic fields for various urban situations, several theoretical approaches are currently under development. One of these is based on the diffusion theory [J. Picaut et al., Acust. Acta Acust. 83(4), 614–621 (1997)]. Whatever the model used, good predictions will be obtained only if the acoustic sources are accurately modeled. Those sources, classified following a qualitative approach, can be issued from traffic (cars, trucks, buses, motorcycles, etc.) but can also have human components (children in a school-yard, people in a market place, on a pedestrian street,...). The aim of this research concerns the modeling of each kind of source. The main parameters retained are the height, the directivity pattern, the sound power frequency spectrum, and the time history. The modeling techniques are based on statistical analysis and inverse fitting procedures on experimental data carried out over a large sample inside each source category. Afterwards, source characteristics will be introduced in the diffusion model and results will be compared with experiments performed on scale models and real urban situations.
Sound field modeling in streets by a diffusion equation
Authors: Picaut Judicaël , Simon Laurent
Published: July 2002

By considering that surface irregularities of building facades are sufficient to produce diffusion in streets, the diffuse sound field modeling by the mathematical theory of diffusion is used to predict sound propagation and reverberation in rectangular streets. This modeling was first developed to predict the sound field in rooms with diffusely reflecting boundaries [J. Picaut, J.-D. Polack, and L. Simon, Acust. Acta Acust. 83(4), 614–621 (1997)]. In this paper, the modeling is applied to urban acoustics without significant modification. A 3-D diffusion equation is derived for the sound energy density and solved for time-varying sources and in steady state. A diffusion coefficient is introduced to characterize the degree of diffusion of the street, and an exchange coefficient depending on the absorption coefficient is used to take the wall absorption into account. When the diffusion coefficient is chosen correctly, predicted reverberation times and sound attenuation are in accordance with experimental data obtained in a scale model of a street. With new developments, by introducing in the model, for example, intersections, moving sources, meteorological effects..., this original modeling should be in the future, a simple solution to predict the noise impact in large urban areas.
Characterization of I. C. engines as a linear acoustic source using internal measurements
Authors: Frikha Slaheddine , Boukhari Samir , Mouton Xavier , Vitel Arnauld
Published: July 2002

Nowadays, faced with international competition, the vehicle constructors are constrained to reduce their studies’ periods and costs. The knowledge of engine acoustic properties as a source exciting its inlet and exhaust pipes is required to perform predictive computations. Present here is a new method allowing engine source characterization as an acoustic pressure source having finite impedance that consists of fitting the engine nonlinear behavior by an equivalent linear one. It is based on a multi-charges approach. Internal pressures at a few points of a set of silencers are used to identify the pressure and the velocity at the outlet of the catalytic converter. The main future of the method is its ability to characterize the engine at realistic functioning conditions. In particular, the inverse model does not include a tail pipe radiation model, so the back pressure may be imposed to a realistic one. That reduces the effects of nonlinearity of the engine and increases the accuracy of the identified source. The internal pressure data are obtained by real measurement since a prototype of the engine exists. Otherwise, they can be computed which allows beginning the design of the exhaust system at an early stage of engine designing.
Characteristics of MRI acoustic noise in functional and high-resolution imaging of the auditory pathways
Authors: Baumann Uwe , Jäger Lorenz
Published: July 2002

The acoustic noise generated by magnetic resonance image (MRI) systems causes problems for the measurement of funtional responses to acoustic stimuli. The time structure and spectral composition of the MRI noise depends mainly on the sequence of gradient switching. As a rule of thumb, faster switching produces more intense noise than slower switching. Functional and high-resolution MRI of the auditory pathways require fast switching sequences to ensure high place and time resolution. To investigate the characteristics of the MRI noise, five different sequences (EPI-fMRI, 3D-MPRAGE, 3D-CISS, 2D-FLASH, EPI-DIFF) were recorded on a 1.5-T device (Siemens Vision) at the position of subject head and also 1.2 m outside the MRI opening to estimate artifacts caused by direct induction into the microphone (B & K 4165). The measured peak SPL inside the MRI varied between 101 and 130 dB depending on the sequence, but a comparison with the results outside the MRI cabinet (87–100 dB SPL peak) revealed for the 3D-CISS and EPI-DIFF sequence an influence of direct induction with an amount up to 20 dB. An ear-related spectral analysis and a virtual pitch calculation was performed to estimate the amount of tonality of each sequence.
BEM and the use of explicit frequency-dependent matrices—A study on computing wave scattering and radiation
Authors: Marburg Steffen
Published: July 2002

The use of explicit frequency-dependent matrices as in finite-element methods has not really been established in boundary element methods yet. The particular integral method (PIM) that may be applied to construct explicit frequency-dependent matrices has already been tested for the solution of interior problems in structural acoustics. However, a formulation for the exterior problem using PIM has not been published. In this paper, the author will discuss ways to apply the PIM to compute wave scattering and sound radiation.
A reflection free boundary condition for propagation in uniform flow using mapped infinite wave envelope elements
Authors: Eversman Walter
Published: July 2002

A new reflection free boundary condition based on mapped infinite wave envelope elements is developed for finite-element modeling of acoustic radiation in a uniformly moving medium. These elements are useful for obtaining closure for computations on an infinite domain in which a radiating body is immersed in a moving medium which is essentially undisturbed outside of the near field. The application described is for harmonic excitation which leads to a model independent of time. An additional result of this study shows that the mapped wave envelope elements provide a boundary condition equivalent to stiffness, mass, and damping matrices appended to the inner mesh. By choosing the transition between the standard FEM mesh and the mapped WE as a surface of constant phase, the mass matrix is caused to vanish identically. This has implications for transient FEM modeling of acoustic radiation. A demonstration of the characteristics of the mapped WE elements is given in the context of acoustic radiation from a turbofan inlet for which benchmark results are known. It is found that for similar computational cost mapped infinite wave envelope elements are superior to conventional wave envelope elements for time-independent formulations.
Acoustic photo- and cinematography based on interference transformation
Authors: Heinz Gerd K. , Nguyen Thanh T. , Duebler Dirk
Published: July 2002

A time-domain technique is introduced to localize far and moving acoustic objects (compare URL http://www.gfai.de/www—open/perspg/heinz.htm). The algorithm is called ‘‘Heinz Interference Transformation’’ (HIT) [Heinz et al.: ‘‘Time pattern, data addressing, coding and topographic maps between multiple connected neural fields—a physical approach to neural superimposition and interference,’’ BioNet’96, Berlin, ISBN 3-00-001107-2]. HIT reproduces mirrored (optical) projections just as nonmirrored reconstructions of different sources depend on the direction of time axis. Based on time-domain calculations, the introduced method reproduces an approximation for different source points in a grid matrix, arranged in an virtual space or array or field in physical dimensions of the measured scene. It is possible to reconstruct acoustic single-time events to cinematographies (movies). Maximum image rate is the sample frequency of time functions. Independent of the integration interval, it is possible to reconstruct in cinematographies the wave field or movies. Properties of HIT, influence of time functions’ properties and channel number, different algorithmical tasks, relations between time and space, aliasing and reconstruction parameters are discussed as examples. [Work supported by German BMWi, Marktvorbereitende Industrieforschung.]
The use of the finite-element method to analyze the influence of depolarization by structuring to the performance of 2D arrays
Authors: Schmitt Daniel , Weber Peter K. , Whatmore Roger W. , Goat Chris
Published: July 2002

3-D ultrasonic imaging can be achieved by steering conventional single-element scanners (pseudo 3-D imaging). The use of 2-D arrays offers a wide range of possibilities for electronic focusing and steering, which will lead beyond the limitations of pseudo 3-D imaging. Measurements of single-array elements have shown that the method of structuring, like dicing, and its process parameters, leads to a decreased coupling factor. This will result in a loss of efficiency and bandwidth. Because this effect can be reduced by repolarizing the array, one can assume a depolarization of a certain depth along the cutting edge of the material. It is very difficult to determine the degree of depolarization and the depth of this dead zone. Using simple geometric models with good aspect ratio and a completely depolarized death zone, the influence of its depth on the coupling factor can be determined. These presumptions are not valid for most 2-D arrays in ultrasonic imaging. Their complex geometry and parameter combinations can be analyzed by the finite-element method. Results obtained from finite-element simulations that are in good agreement with the measurements will be presented and compared with other methods.
A unified linear system approach to ultrasonic radiation from a baffled transducer
Authors: Hays-Stang Kathy J.
Published: July 2002

An acoustic disturbance can be viewed as a waveform in space and time, or by the temporal or spatial frequency content of the acoustic disturbance. For each waveform and frequency viewpoint, the individual Green’s function for acoustic radiation from a baffled transducer is available in the literature. The unified approach allows the Green’s function for any given viewpoint to be transformed appropriately to obtain the Green’s function for a desired viewpoint (personal conversations with the late Bill D. Cook). Given a Green’s function for the acoustic radiation in a linear acoustic system, and the impulse responses of the other system components, the output can be determined for a given input. Choice of the most advantageous radiation impulse response/transfer function can reduce calculation time or provide physical insight for a problem of interest.
Application of a fiber-optical probe hydrophone for in vivo measurements of therapeutical ultrasound
Authors: Dreyer Thomas , Riedlinger Rainer E. , Zenk Johannes , Iro Heinrich
Published: July 2002

Knowledge of sound fields used in therapeutical applications with focused strong ultrasonic pulses in vivo is of great importance to the user and researcher. In this study the ultrasonic field of an experimental high energy pulsed ultrasound (HEPUS) device for tumor treatment is investigated. Using HEPUS, the mechanism of acute tissue destruction is based mainly on cavitation effects in the focal region. A self-focusing piezoelectric transducer generates the applied pressure signal which is a high-amplitude sinusoidal burst with a duration of about 12 μs. These burst signals differ significantly from those in lithotripsy, but have similar amplitudes. A fiber-optical probe hydrophone provides the possibility of minimal invasive pressure measurements in vivo because of its small sensor diameter. During insonification in rabbits, the focal sound pressures and spatial pressure distributions were recorded in the liver and the back muscle in vivo. The fiber tip of the hydrophone was placed directly in the tissue by puncturing, using a cannula. The results obtained are compared with in vitro measurements. They are discussed regarding the influence of attenuation and nonlinear propagation in tissue. Additionally, an error estimation for the pressure measurement in vivo is presented. [Work supported by Wilhelm Sanders Stiftung Gz. 89.030.2.]
Method of measuring and preventing unstable feedback in hearing aids
Authors: Gao Shawn X. , Soli Sigfrid D.
Published: July 2002

Acoustic feedback is a practical problem that can limit the performance and benefit of any hearing aid. In the past, there have been no clinical available methods for accurately predicting the frequencies and gains that will cause unstable feedback for a particular hearing aid in an individual’s ear. The proposed method uses a typical clinical real-ear probe microphone system to acquire the real-ear aided responses by placing the hearing aid in the ear canal and setting the hearing aid gain to two different known settings. The Open Loop Transfer Function (OLTF) of the hearing aid can be derived based on the acquired aided signals. Once the OLTF of the hearing aid is known, potentially unstable frequencies are identified and maximum hearing aid gain and maximum hearing aid insertion gain are determined. The measurement allows the dispenser to modify the desired hearing aid response at only the frequencies that will cause unstable feedback. It consequently eliminates the trial and error method and prevents over-adjustment of the hearing aid. A description of theory and measurement procedure will be provided, as well as examples of its use on KEMAR and hearing-impaired individuals.
Artificial noise signals with speechlike spectral and temporal properties for hearing instrument assessment
Authors: Dreschler Wouter A. , Verschuure Hans , Ludvigson Carl , Westermann Soren
Published: July 2002

The introduction of different forms of nonlinear amplification and noise-reduction algorithms calls for more intelligent ways to specify the properties of hearing instruments. Traditional specifications no longer reflect important characteristics of hearing instruments. Also, for the psychophysical evaluation in a laboratory setting, well-defined noises are necessary; aided speech perception will be largely determined by the properties of the speech signal and the concurrent background noise. The field of hearing instrument specification and evaluation has become a complex area in which traditional tools have lost their relevance. There is a strong need for a new approach based on new test signals that are broadband and dynamic. Standardized broadband noises are required for comparative measurements in different hearing instruments. Based on these notions a working group of the International Collegium of Rehabilitative Audiology (ICRA) started a consensus process to design well-defined artificial noise signals that can become a standard for hearing instrument assessment, both for technical measurements and for applications in the clinical and psychophysical evaluation. This paper reports about the design criteria, the actual realization, and some examples of applications in the measurement of digital signal processing hearing instruments.
Acoustical measurements in marine environmental monitoring and research in the United States
Authors: Ferry Roland E.
Published: July 2002

Acoustical measurements play an important role in marine environmental monitoring and research in the United States. Acoustics is employed by a variety of government agencies with environmental roles and responsibilities, including the U.S. Environmental Protection Agency, National Oceanic and Atmospheric Administration, U.S. Geological Survey, U.S. Army Corps. of Engineers, and the Department of the Interior. The U.S. Environmental Protection Agency (U.S. EPA) has specific coastal regulatory responsibilities mandated by the Clean Water Act and the Marine Protection, Research and Sanctuaries Act of 1972, to limit impacts to the marine environment as a result of wastewater discharges and the disposal of dredged material. To accomplish these tasks, the U.S. EPA and responsible parties use acoustics to gather ambient oceanographic data needed to make environmentally sound decisions regarding ocean outfall and dredged material disposal site placement. Acoustics is also used to assess dredged material and wastewater plume fields to determine the fate and transport of pollutants. In addition, acoustics is used in post-disposal surveys to monitor dredged material impacts to nearby marine communities. Acoustical measurements with real-time data transmission have been successfully used to monitor oceanographic conditions near an ocean disposal site for daily management of disposal activities.
Data-driven modeling of acoustical instruments
Authors: Schoner Bernd , Cooper Charles , Douglas Christopher L. , Boyden Edward S. , Gershenfeld Neil A.
Published: July 2002

Comprehensive digital analysis and synthesis of musical instruments using direct observations of their physical behavior have been developed and implemented for the violin. In a training session, control input data from unobtrusive bow and finger sensors is recorded simultaneously with the violin’s audio output. These signals are used to train a cluster-weighted probabilistic prediction model that reproduces the nonlinear relationship between the control inputs and the target audio output data. Cluster-weighted modeling was developed to apply previous results from linear systems theory and time-series approximation theory in the broader context of a globally complex and nonlinear model. The presented sound synthesis engine makes use of familiar sound synthesis techniques, but extends them with a complex input/output framework that naturally incorporates dynamic control. The final system predicts audio data based on new control data. While a violinist plays the interface device (a silent violin), the computer model reproduces the sound of the original violin. Recent work has extended the system of sensors and algorithms to model string vibration dynamics as well as the radiated sound.
Method for time-domain localization of stochastic noise in quasiperiodic signals
Authors: Guettler Knut
Published: July 2002

In order to establish knowledge on the sources of noise in nearly periodic signals, it is essential to apply methods that give the best possible resolution in the time domain. Of particular importance is this kind of analysis when attempting to synthesize low-pitched bowed string instruments, where most of the noise appears in pulses. The present method isolates the noise from the signal without the use of any nonrectangular window or zero padding. This can conveniently be done by combining FFT with the Bluestein filter [L. I. Bluestein, Nerem Record, 218–219 (1968)], which allows the number of elements under analysis to be arbitrarily chosen as an exact integer product of the signal period. The suggested method minimizes leakage to neighboring elements when returning to the time domain after the deterministic/stochastic signal separation, thus providing a very reliable separation between the two signal components in both domains. Sound examples will be given for several instruments.
Comparison of five perceptual timbre spaces of violin tones of different pitches
Authors: Štěpánek Jan , Otčenášek Zdeněk , Melka Alois
Published: July 2002

Violin timbre was studied for five tone pitches (H3, F ♯4, C5, G5, D6). A set of violin tones played on different instruments was recorded in an anechoic room. The recordings were subsequently manipulated to weaken an influence of tone transient parts on the perception. Two pair listening tests in headphones were performed for each pitch: timbre dissimilarity scaling test and spontaneous verbal description of timbre dissimilarities. A perceptual timbre space was constructed from the results of dissimilarity scaling test for each pitch using the multidimensional scaling method. Projections of verbal descriptions into the perceptual spaces enabled their external interpretation. Some perceptual attributes and pairs of attributes of violin timbre were established (‘‘narrow,’’ ‘‘rustle,’’ ‘‘soft’’–‘‘sharp,’’ ‘‘dark’’–‘‘bright,’’ ‘‘clear’’–‘‘blurred’’) based on correlation analysis of word occurrence frequencies on individual tones and on comparison of word projection coordinates in perceptual spaces. Comparing the results for five studied pitches it was possible to pronounce the hypothesis of salient violin timbre dimensions.
Recent results on ‘‘unison quality,’’ or finding objective and quantitative criteria to decide that a piano is perfectly tuned
Authors: Causse Rene E. , Marandas Eric , Thomas Olivier
Published: July 2002

The difference in tuning (mistuning) between the three strings of a unison group is the parameter used by the tuner to adjust for each note the double decay of the sound, characteristic of piano tones, generally from the notes F1 to C5. However, in the case of important irregularities in hammer stricking, increasing the mistuning to adjust the double decay (slope and relative level of each decay) is not sufficient and only the proper adjustment of the regularity of the action of the hammer would lead to a better temporal evolution of the sound [Causse et al., Proc. ISMA’98]. To further explore what tuners call ‘‘unison quality,’’ which means finding objective and qualitative criteria to decide that a piano is well tuned, the double-decay of the first partials of notes of a piano with different ‘‘unison qualities’’ and different hammer stricking irregularities was measured. In parallel, a simple simulation was refined of the vibration of a unison group of strings where excitation irregularities were simulated by varying the initial displacements and velocities of the strings. In this presentation, results of simple listening tests done with piano tuners will be presented.
Space-induced distortion of starting transient of musical sound
Authors: Domitrovic Hrvoje , Maletic Mladen , Fajt Sinisa
Published: July 2002

Musical sound can be defined as complex sound that begins with a starting transient followed by a (more or less) steady sound and ends with a decaying sound. After that, continuous movement from one frequency to the another follows. The rate of change of loudness for partial tones that are greater than a certain threshold and their relative starting times are different for miscellaneous musical instruments. Recognition of a particular musical instrument depends upon short starting and ending transients. Relative starting time of the starting transient’s partial is limited by the rate of change of loudness that is greater than 600 dB/s. The envelope of all rates of change defines the maximum rate of change for loudness levels and partials that dominates in a certain time interval. The beginning transient is the complex phenomena, assessed with early sound and rate and synchronized with the rise of loudness and dominant partial tone in the observed time interval. The just-noticeable threshold of rates of loudness change for partial tones for various musical instruments in different acoustically treated spaces was measured and described in this paper.
Prospects for active noise control in power plants
Authors: Warnaka Glenn E. , Walker Bruce E.
Published: July 2002

Active noise control has been applied in power plants to suppress noise from a variety of sources. Applications have included combustion fans, large exhaust stacks, emergency diesel generators, dust collectors, high temperature exhausts, etc. Active noise control systems have been used to control the noise from fan blade passage frequencies, turbine blade frequencies, and other similar noises. In addition, tests have been successful in suppressing random noise, especially at low frequencies. Active noise control has also been used to extend high-frequency attenuation beyond the usual frequency range by using the active noise control systems to spoil the symmetry of the duct and so prevent cross-mode formation. In other cases, active noise control has been coupled with known elements of passive noise control to achieve synergistic results. Active noise control sources can be protected from difficult environments such as high-flow velocities, weather, and high temperatures by using waveguides or Helmholtz resonators between the active sources and point of attack in the environment. This paper presents a view of future developments in active noise control that can be realized by the extension of current active noise control methods to new and challenging applications.
Simnoise: A new low-traffic-flow road noise estimation by a statistical approach
Authors: Licitra Gaetano , Cerchiai Mauro , Canessa Silvia
Published: July 2002

Road noise models usually limit the possibility of sound-level prediction with low vehicular fluxes, especially during the night period, because they provide urban traffic noise with a minimum number of some hundreds of vehicles per hour. In order to predict sound levels in urban areas for both night and day periods and to plan corrective actions, a model that can be applied in case of very low traffic flows (even lower than 50 vehicles for hour) is proposed here. This model uses a Monte Carlo method based on a dependent Poissonian vehicle distribution, a spatial Gaussian one with respect to the lane center, and a Cauchy distribution for velocities. These are estimated using the English Road Research Laboratory model, calibrated using only geometrical site description and vehicular fluxes informations, based on 75 measurement points in a speed range between 20 and 60 km/h, for almost 230 hourly night Leq levels. The prevision values resulted in good agreement with actual values with an error depending on the entries. For the range between 10–2000 vehicles, an error was observed of about 1–2 dB on the actual value.
On energy definition in electromagnetism: An analogy with viscoelasticity
Authors: Carcione J. M.
Published: July 2002

Electromagnetic media as, for instance, imperfect dielectrics, semiconductors, and materials with magnetic losses, have time- (and frequency-) dependent permittivity, magnetic permeability, and electric conductivity, and, therefore, energy dissipation and pulse distortion occurs. The electromagnetic Umov–Poynting’s theorem is reinterpreted in light of the theory of viscoelasticity in order to define the stored and dissipated energy densities in the time domain. A simple dielectric relaxation model equivalent to a viscoelastic mechanical model illustrates the analogy that identifies electric field with stress, electric induction with strain, dielectric permittivity with reciprocal bulk modulus, and resistance with viscosity.
The sound quality of the Teatro Comunale in Treviso, Italy
Authors: Tronchin Lamberto
Published: July 2002

The Teatro Comunale of Treviso was designed at the same time as the Teatro La Fenice of Venice, in the middle of the 19th century. Treviso being so close to Venice, the reputation of the Venetian Theatre, just rebuilt after the burning of 1836, influenced the municipality of this little town, which decided to design the Theatre with the same shape as la Fenice. After the burning of 1996, and following the disappointment of losing such unique architecture and sound quality, acoustical measurements were performed in many Italian theatres, especially in historic theatres where acoustical measurements were never before undertaken. In this paper, the results of the acoustic measurements are presented. According to ISO 3382, binaural measurements, with a dummy head, have been performed in 25 positions in the hall, with different positions of the sound source in the proscenium. Acoustical parameters, such as EDT, G, LE were calculated from the impulse responses and mapped. Also, Ando’s quality maps of preferences, with reference to two different kinds of musical signals, were accomplished from experimental measurements. From the measurements, a good behavior of the theatre has been pointed out, even if some limitations in some positions have been discovered.
Paradoxical lateral suppression in the dolphin’s auditory system
Authors: Popov Vladimir V. , Supin Alexander Ya.
Published: July 2002

A paradoxical phenomenon was found in the auditory system of dolphins: weak sounds suppressed the brain-evoked potential responses to much stronger sounds. This occurred when the brain-evoked potentials were elicited by rhythmically amplitude-modulated sounds at modulation rates from a few hundred to more than a thousand Hz. The rhythmic-evoked response (the so-called envelope-following response) was markedly suppressed by addition of another sound of higher frequency and down to 40 dB lower intensity than the amplitude-modulated stimulus. This phenomenon was called the paradoxical lateral suppression. Only the sustained rhythmic response was a subject of this suppression, while the transient on-response to the stimulus onset was not suppressed, thus indicating that the suppression influenced the ability of evoked potentials to follow rapid amplitude modulations. At certain conditions the paradoxical lateral suppression prevents weak sounds from being masked by stronger ones. When a complex sound consists of two carriers—a higher-level, lower-frequency and a lower-level, higher-frequency, the paradoxical lateral suppression results in that evoked responses follow modulation of the weaker carrier, not the stronger one. It may help a dolphin to perceive weaker echo signals in the background of stronger emitted pulses.
FEM simulations of horn loudspeakers and their experimental verification
Authors: Jost Armin , Kressmann Reiner
Published: July 2002

Horn loudspeakers are in common use for sound reinforcement of large rooms because of their high efficiency. In the design of horn loudspeakers, special care has to be taken on the horn’s geometry and its interaction with the properties of the driver. In the present work, the finite-element analysis of these coupled acoustical–mechanical systems is compared with classical analytical and finite-difference methods. All simulations are compared with experimental data, obtained from two different horn loudspeakers: First, a folded bass cabinet transducer and, second, a midrange horn loudspeaker. The bass cabinet is 50×54×104 cm in size; the midrange horn measures 40×44×44 cm. Both cabinets are made from wood; therefore, the horn’s geometry can only be approximated to the ideal exponential characteristics. In general, the effect of finite horn length, resulting in reflections at the mouth due to mismatch in acoustical impedance, has to be considered. The bass horn, especially, has to be simulated very precisely, since this loudspeaker shows higher impedance mismatch. The finite-element simulations carried out with ANSYS show excellent agreement with the measurements. The sound-pressure level generated was investigated as a function of frequency and angle of radiation.
Education in acoustics: Fundamentals and peculiarities
Authors: Dubrovsky Nikolai A. , Dogadov Albert A. , Sigov Alexandr S.
Published: July 2002

An historical background of university and technical high school education in acoustics in Russia is considered. Basic features of Soviet concepts of training in acoustics are discussed. Main advantages are deep and broad training in basic and applied disciplines, a system of the ‘‘base’’ research centers for early research activity of students under leadership of active scientists, and reporting by students of their results in science and technology at conferences and seminars. These advantages had been very positive for the Soviet planned economy. The main drawbacks are redundancy and rigidity of this education system. Transition to free market society forced the modification of basic concepts of education in acoustics: to introduce flexible education similar to European and American ones, to train students in new areas of acoustics intended to enhance the quality of life (ecology, medicine), to provide optional training in acoustics (common or individual), to meet requirements of private enterprises to education of selected students. A new approach to training of foreign students is developed: transition from special high schools for foreigners to joint education of foreigners with Russian citizens in many state educational centers. The role of the Russian Acoustical Society in exchange of education methodology between training centers in Russia is presented.
Advances in acoustic remote sensing of the atmosphere at the IAO SBaa RAS
Authors: Krasnenko Nikolai P.
Published: July 2002

Advances in acoustic remote sensing of the atmosphere made at the Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences (Tomsk, Russia) for a 24-year period are considered. Sodars developed at the IAO are described. Results of theoretical analysis of methods for acoustic sounding of the atmosphere are presented including the interaction of the acoustic radiation with the atmosphere, optimization of the sodar parameters, and accuracy of sodar measurements of the atmospheric parameters. The emphasis is on investigations of the effect of acoustic refraction on the sodar operation as well as on search for new information capabilities in acoustic sounding. Results of investigations of the parameters of the atmospheric boundary layer above dry land and ocean and airports with the sodars developed at the IAO are given. Sodar-derived data are compared with the results of lidar sensing and ballon and radiozonde measurements of the atmospheric parameters.
Piezoelectric interfacial waves in directions of vanishing slowness curvature
Authors: Danicki Eugene J.
Published: July 2002

Piezoelectric interfacial waves can propagate in a piezoelectric body along the conducting plane embedded in it (that is, at the bonding of two metallized pieces of a crystal); its velocity is close to one of the shear bulk waves. The wave-field penetration depth depends on the shear wave slowness curvature. At investigated propagation directions of vanishing curvature, the wave decays at about two or more wavelengths. There are only a handful of such points in investigated crystals: 12 distinct ones in quartz and 6 in lithium niobate. They are analyzed applying Stroh formalism (the case of fourfold defective matrix), and using the recently developed ‘‘papal’’ approximation to the planar harmonic Green’s function. In almost all cases, the approximation evaluated at a given wave number is accurate enough for application in a sufficiently wide wave number domain. This is beneficial for physical interpretation of numerical results. (The method can also be adopted for analysis of Rayleigh and pseudo surface waves in anisotropic crystals.) Possible applications of the investigated waves include: (a) low-temperature investigations of materials or superconducting layers (propagating inside the crystal, the wave is well protected from an adverse environment), (b) validation of material constants, and (c) in surface acoustic wave devices.
Application of the piezoelectric implant method to study the frost phase in frozen porous media
Authors: Pouyez Stephane , Hazebrouck Robert
Published: July 2002

This work describes the adaptation of the piezoelectric implant method for frozen porous media. This technique has been successfully used for monitoring cement setting [S. Pouyez and R. Hazebrouck, Biot Conference on Poromechanics (1998)]. Earlier results have shown that, for porous media, the electrical impedance resonance peak of the implant can be calculated by Biot’s theory. The slow wave has a predominant contribution to the piezoelectric disc response. Experiments in glass beads embedded in water monitored in a temperature range of [−20, 10 °C] are presented. Results are in good agreement with those obtained by using the transmission of longitudinal waves. The implant method is very sensitive and free of any problem caused by the mechanical contact occurring in most existing methods using ultrasonic velocities measurement. Thus in the vicinity of 0 °C and for positive values of the temperature, the proposed method allows one to follow the slow reheating of the sample while ultrasonic measurement becomes less efficient because of the attenuation. The implant remains in the sample, so the frost and defrost cycles for heterogeneous materials in civial engineering can be monitored with this method. The implant method also might be of interest for the study of frozen soils.
Should normalization be included in cross-correlation-based models of binaural processing?
Authors: van de Par Steven , Trahiotis Constantine , Bernstein Leslie R.
Published: July 2002

It is generally accepted that cross-correlation-based models of binaural information processing provide excellent qualitative and quantitative accounts of data obtained in a wide variety of experimental contexts. These contexts include binaural detection, lateralization, localization, and the perception of pitch mediated by strictly binaural cues. The purpose of this research was to investigate the application of ‘‘normalization’’ as part of the computation of indices of interaural correlation. Such indices have often been utilized to account for binaural detection data but the normalization, to our knowledge, has neither been explicitly studied nor evaluated on its own merits. Normalization ensures that the value of correlation obtained with identical inputs will be +1 (or for polarity-opposite inputs, −1). Nevertheless, normalization, as a stage of processing, is not overtly included in modern cross-correlation-function-based models. In this presentation logical arguments and new data regarding the need to include normalization within cross-correlation-based models of binaural detection/discrimination are provided. The new data were obtained while roving the overall levels of the stimuli in a binaural detection task. The data indicate that, to account for binaural detection, an extremely rapid and accurate stage of normalization must be included in cross-correlation-based models. [Work supported by NIH-DC-02103 and NIH-DC-00234.]