Showing papers in "Applied Acoustics in 1993"

TL;DR: The ODEON room acoustics program is intended to be a base for research in objective and subjective room acoustic research, and a useful tool for consultants, in which an initial ray tracing is carried out to determine potential reflection sequences.

TL;DR: In this paper, a beam tracing method for finding image-receiver paths using triangular section beams is suggested where the source of these beams is omnidirectional and the beams do not overlap.

TL;DR: In this article, the problem of measuring the sound-absorption coefficient in situ is approached in a systematic way, accounting for parasitic reflections and background noise, and the basic reflection method is improved by using pseudo-random binary sequences of maximum length as the test signal.

TL;DR: In this article, the authors considered two kinds of inherent systematic errors of ray tracing, namely, errors due to a detection problem and limitations due to limited spatial resolution, and showed that the detection errors can be eliminated without significant increase in computation time.

TL;DR: In this article, an analogy between billiard trajectories and sound rays is made, which makes it possible to derive ergodic properties for sound rays and to estimate the average number of rays reaching a receiver at any time.

TL;DR: The Epidaure software package as mentioned in this paper is intended to be an efficient design tool in room acoustics, and two major features are discussed: the prediction of objective criteria from calculated energy responses (commonly designated as echograms), and the aural simulations based on predicted impulse responses.

TL;DR: In this paper, an approach to add a diffuse background signal to the result of an image source method, in which only the specular parts of the reflections are considered, is described.

TL;DR: In this paper, the authors used a theory for one-dimensional wave propagation in elastic porous media that makes allowance for two longitudinal wave types, i.e. airborne and frame-borne waves.

TL;DR: In this article, a method of measuring the frequency dependent flow resistance and reactance of porous materials in a duct is presented and examined, which involves measuring the transfer function between the signals from two microphones placed on either side of a sample of the material.

TL;DR: In this article, a method for determining the vibration modes of geometrically nonlinear beams under various edge conditions is presented. But the method assumes a continuum periodic solution which allows the harmonic balance principle to be employed to derive modal components that satisfy the equation of motion exactly.

TL;DR: In this paper, a simplified method for modelling the reflection at a surface is proposed, where the surface is assumed to be locally reacting, and as an approximation the impedance is real.

TL;DR: In this article, the authors discussed the extrapolation of number of visible image sources and average image source distances to higher-order specular reflections from low-order calculated results, and discussed methods that might be used to accelerate such calculations.

TL;DR: In this paper, a set of acoustical and meteorological data from an outdoor sound propagation experiment was presented, which was done in a farm field near Rock Springs, Pennsylvania, on 7 July 1990.

TL;DR: In this paper, the accuracy and computational times of theoretical methods used to predict the scattering from rigid plane and curved reflectors have been evaluated, based on different solutions of the Helmholtz-Kirchhoff integral equation.

TL;DR: In this paper, the authors present a computer-aided procedure for digital signal processing for binaural aural evaluation and evaluation of acoustic qualities of auditoria, based on the prediction of both objective and subjective properties of sound fields.

TL;DR: In this article, the effect of the frame wave on the surface impedance of a layer of fibrous material, and on the transmission through a fiberglass material bonded onto a plate is studied with this new model.

TL;DR: In this paper, the authors discuss building standard norms which exist in Belgium, France, England, Germany and Holland, and which comfort is considered, the minimum or the maximum, considering that numerous factors such as exterior noise (for example, the absence of noise) or reverberation time (standardized formulas) are not always taken into consideration.

TL;DR: In this article, a numerical scheme for solving the three dimensional interior acoustic problem governed by the Helmholtz equation has been developed and the main feature of this formulation is that the singularity can be removed analytically.

TL;DR: In this paper, the authors describe the design and implementation of a vocal pitch matching development assessment system, and illustrate its operation with results gained from an experienced singer, which is a development from an earlier system, although much more limited in its scope, has nevertheless been shown to be useful in primary school music teaching.

TL;DR: In this paper, a study of harmonic plane wave propagation through an anisotropic, periodically layered, fluid-saturated, porous medium was made, and the field equations governing the wave propagation were derived in terms of first-order ordinary differential equations.

TL;DR: In this paper, a new method for estimating the probability density function of traffic noise is proposed based on the hypothesis of the normality of emitted noise by each single noise source as well as the distribution of traffic flow which depends upon the type of the traffic.

TL;DR: In this paper, the degree of interaural cross-correlation can be widely applied as a physical factor to estimate auditory source width (ASW) perceived in any sound field.

TL;DR: In this paper, a reflection-symmetric pentagonal gong made from steel rod was designed to provide partial tones in nearly harmonic relationship, in order to achieve a musically satisfactory bell-like sound.

TL;DR: In this paper, the sound intensity technique has been tested on sound insulation measurements under laboratory conditions, and it is shown that agreement with traditional measurements of the sound reduction index is excellent.

TL;DR: In this paper, a social survey based on the noise environment at residential sites both in Nagoya, Japan and in Beijing, China has been carried out and the analysis and results of the surveys and discussion on the difference between the reactions of residents in the two cities to their noise environments are given in this paper.

TL;DR: In this article, the importance of the radiation impedance in determining the input impedance of musical horns is examined, and the results thus obtained enable the finding that the horn function, as defined by Benade and Jansson (Acustica, 31 (1974) 79-98), contains most of the information needed to compute the input signal impedance.

TL;DR: A pilot study comparing a computer image source model of an auditorium to its corresponding 1:50 scale model indicates that the methods generally give results for common room acoustic measures which are in reasonable agreement with regard to measurement uncertainty.

TL;DR: In this paper, an indirect method of measuring the acoustic surface impedance of a porous material is described, where data collected from pairs of vertically separated microphones near to a point source placed above the material surface are used together with a minimisation routine to evaluate the impedance of the surface.

TL;DR: In this article, an attempt is made to derive hydroacoustic scaling laws for the dominant noise sources involved, including Turbulent excitation of a fluid mass, volume pulsations due to cavitation and dramatic effects due to but small geometrical modifications at a flow restriction.