Showing papers in "Applied Acoustics in 1992"

TL;DR: In this paper, the fundamental ideas of the binaural recording technique are discussed and a model is given that describes the sound transmission from a source in a free field, through the external ear to the eardrum.

TL;DR: The theory of the parabolic equation method and the manner in which a finite difference numerical solution scheme can be constructed are presented in this paper, where the treatment deals with both narrow and wide angle cases.

TL;DR: Binaural room simulation is a method of allowing for listening into non-existing spaces by means of a computer model that takes all acoustical relevant parameters of the environment into account.

TL;DR: In this article, the effects of curved rays and the loss of coherence due to atmospheric turbulence were considered for propagation from a point source above an impedance plane, and the total sound pressure level was computed by summing the contribution from all the rays.

TL;DR: In this paper, the effects of small spatial variations on each parameter are evaluated and compared to reproducibility and within hall variations, and the critical problem of hall to hall comparisons is considered.

TL;DR: Schroeder diffusers of the quadratic-residue type in two dimensions were constructed in this article, and their absorption coefficient was very large in the frequency range below the lower limit of the design frequency.

TL;DR: Four types of numerical expression of Maekawa's chart for the design of an acoustical barrier are presented and the maximum deviation of the calculated values from the readings of the chart is within 0·5 dB in the range of the Fresnel numbers.

TL;DR: In this article, results from measurements and theoretical calculations of the sound reduction index of some double walls are presented, and it is shown that a fairly good agreement can be obtained if a much lower value of the flow resistance than the actual one is used for the calculations.

TL;DR: In this paper, a large microcomputer data base using design curves generated to cover the entire range of manufactured rectangular silencers was made available and the insertion loss of the silencers is estimated from attenuation rates calculated from a finite element method, which can be extended to account for the effects of shearing airflows in the airway.

TL;DR: In this article, a short survey of the development of artificial-head technology is followed by an explanation of the physical principles of the head transfer function and a model description of the acoustically effective elements.

TL;DR: In this article, the authors describe a sound field measurement method which is aimed at analysing spatial information of the sound field in a room using four microphones and each of them is installed at the apex of a regular tetrahedron.

TL;DR: In this paper, the effect of including in-plane waves in a statistical energy analysis model of a building is examined and it is shown that the additional waves make little difference close to the source, but large differences can occur far from the source if they are omitted.

TL;DR: In this paper, the authors used geometrical, pseudostatistical and purely statistical methods for the prediction of the binaural impulse response in room acoustics simulations.

TL;DR: In this paper, the insulation of noise by folded panel partitions made of several layers of nonwoven fiberwebs and a layer of woven fabric was examined, and the resulting transmission loss of the composite structure was an oscillatory function of the opening angle between the individual panels.

TL;DR: In this article, the authors investigated the acoustics of three contemporary concert/recital halls by measurement and calculation, and by asking users to comment on the perceived acoustical qualities.

TL;DR: In this article, the authors investigated the vibro-acoustic behavior of a finite cylindrical shell on which attached internal spring-mass systems and point defects are simulated in order to understand the radiation of machinery with a cylinder-shaped hood.

TL;DR: In this article, the authors review the usefulness and validity of the guidelines available to designers and look at whether there are limits on the building form which must not be exceeded and propose another approach to acoustic design which is based on a statistical analysis of the form of existing auditoria.

TL;DR: In this article, a simplified analytical model of the Flextensional transducers is presented based on the assumptions of elliptical beam bending and cylindrical shell radiation similar to the mathematical model presented by G.A. Brigham in 1974.

TL;DR: In this paper, the authors measured the attenuation that may be achieved by wearing an earplug and an earmuff in combination, and the results showed that the combined attenuation fell short of the sum of attenuation scores achieved with each device worn separately.

TL;DR: A test facility at Instituto de Pesquisas Technologicas in Brazil is described in this paper, which enables the internal loss factor of building materials to be measured for full sized walls built under realistic conditions.

TL;DR: Reactions to the problem of environmental noise were studied by obtaining responses from the residents of 43 different locations in the city of Visakhapatnam in a social survey by correlating the mean dissatisfaction parameter with different noise indices.

TL;DR: In this paper, the authors measured the spectral level of free water and embedded cases of small explosive charges and showed that the difference in spectral level is the least at low frequencies. But the results may be used to apply standard formulae for the pressure from free water charges to those for embedded charges, and hence to calculate safe charge sizes.

TL;DR: In this paper, a number of different designs for sound transmission suites are examined and their performance computed for standard walls, and it is found that the performance of the system depends on both the test wall and the design of the chambers.

TL;DR: Different forms of the algorithm are discussed and the form suitable for convex polygons is optimized from a viewpoint of execution time, and a room shape analysis is employed to obtain an additional improvement of the algorithms efficiency.

TL;DR: In this paper, the relationship between geometrical parameters, acoustical criteria and subjecive characteristics of sound spatialisation in concert halls was investigated using multiple correspondence analysis.

TL;DR: In this paper, a system which automatically achieves the desired filtering by the arrangement of the play-back transducers or earphones, and by the proper selection of the microphones is described.

TL;DR: In this article, two materials, placed over the corner walls surrounding a gas turbine unit in five different geometric configurations, are tested to establish their effectiveness on the noise field of a 45 kW turbine unit, and the measured noise without wall treatment reveals that about 46% of the noise radiated acoustic power of the unit is in the 1 3 octave band of 12 500 Hz central frequency.

TL;DR: Experimental data are presented to illustrate the effects of alternative design approaches to the problem of variability in cancellation achieved throughout the ear-muff cavity, and consequently the level of attenuation perceived by the user.

TL;DR: In this article, the fluid-structural coupled response of piston type transducers in underwater arrays can be easily determined using simple numerical techniques, and a matrix equation is formed coupling the mutual impedance with the structural response of the transducers.