Showing papers in "Applied Acoustics in 2004"

TL;DR: In this paper, the performance of barriers having different shapes and surface conditions were tested using the boundary element method in a well-controlled environment and the insertion losses for six receiver positions were averaged and compared.

TL;DR: A detailed experimental study has been conducted to determine the effect of adding hollow ceramic-micro balloons, also known as cenospheres, on the acoustic properties of cement matrix and asphalt concrete as mentioned in this paper.

TL;DR: In this paper, a technique for structure damage detection based on spatial wavelet analysis is presented. But this method only needs the spatially distributed signals (e.g. the displacements or mode shapes) of the rectangular plate after damage.

TL;DR: The results suggest that traffic noise constitutes a serious problem for at least 15% of the breeding bird community in western-central Spain.

TL;DR: In this article, a psychoacoustic study was conducted to characterize listeners' preferences for a set of sounds produced by different brands and models of indoor air-conditioning units, and some synthetic sounds, created by interpolation between recorded sound samples, were integrated into the set.

TL;DR: In this paper, a high-power laser beam is focused at a point, the air at the focal point is heated to temperatures of thousands of degrees within several nanoseconds and breaks down This generates a spark that, in turn, is accompanied by an acoustic shock wave.

TL;DR: In this article, exposure-effect relationships between the level of road traffic noise at the most exposed side of a dwelling's facade and the residents' reactions to road traffic noises have been estimated.

TL;DR: In this article, a noise map of the city of Valdivia is created as a way to evaluate the city's noise, and the day-evening-night level LDEN is used as the rating method to describe long-term annoyance.

TL;DR: In this article, a simple method for diagnosis of railway wheel defects using fuzzy-logic is proposed, based on vibration measurements at different train speeds on healthy wheels and wheels with defects known a priori.

TL;DR: In this article, the authors compared the predicted values for acoustic insulation of single and double panel walls, using analytical models previously developed by the authors, compared with experimental findings, and concluded that the predictive analytical solutions are in good agreement with the experimental results, except when the area of the panels is very small and the frequencies are very low.

TL;DR: In this paper, the effects of meaningful and meaningless external acoustical noise, at various sound pressure level values, on participants during a mental task was described, and the difference between subjective feelings of ''fatigue' before and after the task, both with and without noise was considered.

TL;DR: In this paper, the influence of two transverse open cracks on the antiresonance of a double cracked cantilever beam is investigated both analytically and experimentally.

TL;DR: In this article, a frequency power law is suggested and discussed to describe damping behavior with special respect to the low loss resilient materials used for sound and vibration control, and the dynamic modulus as a function of frequency is determined from the loss modulus through the Kramers-Kronig dispersion relations.

TL;DR: In this paper, the authors describe an efficient algorithm for acoustic analysis of any general silencer system, which is based on the identification of sub-systems of two-port acoustic elements.

TL;DR: In this article, the authors measured the random-incidence scattering coefficient of surfaces in a diffuse field, and the scattering coefficients of different sizes and densities of wooden hemispheres and cubes were measured in model-scale reverberation rooms.

TL;DR: In this paper, the authors present the acoustic performance off tall building facades closed to roadway due to one of balcony configurations, namely ceiling, with an inclined form in terms of traffic noise reduction.

TL;DR: In this article, the performance of the existing noise prediction models in predicting traffic noise from inclined roads is evaluated by regression analysis and simple physical consideration of the traffic noise production mechanisms, formulae for the prediction of the LA10, LA50, LA90 and LAeq are developed or re-calibrated.

TL;DR: In this article, an efficient method based on the uniform design theory is presented, which is very different from the empirical method and is accurate and simple for implementation for structural vibration measurements.

TL;DR: In this article, a dynamic transfer matrix method for determining natural frequencies and mode shapes of the bending-torsion coupled vibration of axially loaded thin-walled beams with monosymmetrical cross sections is developed by using a general solution of the governing differential equations of motion based on Bernoulli-Euler beam theory.

TL;DR: In this article, a finite element model is applied to the vibration of a rotating blade with a single edge crack and the effects of transverse shear deformation and rotatory inertia are taken into account.

TL;DR: In this paper, a 2D software analysis based on the vortex surface method (or potential flow method) was carried out to evaluate the aerodynamic performance of axial flow fans.

TL;DR: In this paper, the authors introduce an outdoor sound simulation that is fully compliant with ISO 9613 with some complementary methods that enhance its applicability; for example, calculation of sound attenuation due to undulating terrain in octave bands, geometric divergence in the near-field of the source, and short-term wind effects.

TL;DR: The shape optimization of multi-segments muffler coupled with the GA searching technique is presented and results verify that the optimal sound transmission loss at the designed frequency of 500 Hz is exactly maximized.

TL;DR: Wang et al. as mentioned in this paper performed traffic noise surveying and analysis along four main roads in the Beijing urban area, the 2nd, 3rd and 4th ring roads circling the central downtown area and Chang-An Avenue, a major east-west corridor through the heart of the city.

TL;DR: In this paper, an analytical approach for vibration response analysis of a beam with single passive constrained layer damping (PCLD) patch is presented, where the governing equation of motion of the beam is firstly derived on the basis of an energy approach and the Lagrange equation.

TL;DR: In this paper, a simple model that assumes a flat city on rigid ground is used to demonstrate that sources from a large area are important, and the proposed method predicts levels 6-10 dB too high for the equivalent level at all measurement positions.

TL;DR: In this paper, a boundary element code performing the sensitivity analysis of the acoustic pressure by using the matrix sensitivities with respect to different design variables has been developed, and the effect of the precision of boundary element discretization on acoustic pressure sensitivity is examined via this code.

TL;DR: In this article, a field study has been carried out in urban Assiut city, Egypt to evaluate road traffic noise levels, to determine if these levels exceed permissible levels, and to examine people's attitudes towards road traffic noises.

TL;DR: In this paper, the authors measured the acoustical characteristics of 14 university classrooms at the University of British Columbia (UBC) before and after renovation and evaluated the quality of verbal communication in the classrooms using room-average Speech Intelligibility and its physical correlate, Speech Transmission Index (STI).

TL;DR: In this paper, the results of experimental studies of the noise of a residential split-system air-conditioner unit were presented, where the compressor and condenser and associated fans were removed from the unit and did not form part of the studies.