Showing papers in "Applied Acoustics in 1987"

TL;DR: In this article, it was shown that the road surface type and conditions may influence the traffic noise by up to 11 dB(A) for free-flowing traffic. But the authors also pointed out that the effect of road surface on traffic noise is complicated and it is very difficult to generalize any simple relations.

TL;DR: In this paper, a review of 20 past survey procedures shows that the surveys can be categorized into four types: random sampling, sampling by land-use category, receptor-oriented sampling, and sourceoriented sampling.

TL;DR: In this article, the forms and vibrational modes of carillon bells and handbells are discussed and compared, and different timbres are traced to the differences in the vibrational behaviour and the resulting spectra of partial tones.

TL;DR: In this article, the authors reviewed the evidence that is relevant to any expert appraisal which formed part of a scheme of exemptions from the otherwise mandatory requirement of hearing protection in the European Economic Community.

TL;DR: In this article, an experimental procedure for determining coupling loss factors for Statistical Energy Analysis was described, and numerical procedures for carrying out that optimisation efficiently are outlined, and illustrated with (artificial) examples.

TL;DR: In this article, a survey of the development of generalized SIL curves is described and new SIL curves are proposed, and a method to determine the communication quality is described, which includes both the speaker's effort and the intelligibility reduction at the hearer's position.

TL;DR: In this article, a computer model is described for predicting noise levels generated by urban road traffic under interrupted flow conditions, which is composed of two subsections: the first predicts propagation characteristics of sound in typical street configurations and the second simulates the flow of road traffic in urban areas.

TL;DR: In this paper, the background levels (L 90 ) from road traffic are high, with half of the study population exposed to levels some 20 dB above those measured in a UK study of the (whole) population of England.

TL;DR: The results of measurements carried out at 22 main road sites surfaced with pervious bituminous materials have confirmed that the low levels of vehicle noise observed for these surfaces, when constructed under laboratory conditions and tested with single vehicle noise sources, were also achieved under normal road conditions and for random vehicles drawn from the traffic stream.

TL;DR: In this article, an extended sound intensity method for determining sound reduction indices is presented, containing additional terms to account for the size of the measurement surface, boundary interference effects and calibration mismatch, and the absorption error increases with the flanking ratio and with the fraction of the total receiving room absorption located on the surface of the test object.

TL;DR: In this paper, the authors investigated the effectiveness of several different materials on the reduction of blast noise produced by detonating high explosives, and the results provided some insight into the dominant mechanism for energy transfer between the shocked air and the blast reducing materials.

TL;DR: In this article, a procedure to measure industrial impulse noise was developed that provides information on both the equivalent noise level and impulsiveness, defined as the difference between the A-weighted peak level and the root-mean-square level.

TL;DR: In this article, the sound intensity measurement technique is employed to determine the transmission loss of panels in a laboratory situation, and an experimental procedure is established, the technique validated, and subsequently exploited to determine transmitted intensity contours for two sizes of panel, as well as to examine the influence of a deliberately introduced construction fault.

TL;DR: In this paper, the authors investigated the attenuation provided by enclosing a blast reducing material (aqueous foam) in a rigid vessel (cylindrical metal culvert), open at one end to the atmosphere.

TL;DR: In this paper, a number of commonly used excitation arrangements (spherical point contact and a small flat stud contact excitation, both with flexible drive rod arrangements of various diameters, and a free floating magnetic exciter) are compared.

TL;DR: In this article, the measured values of the sound pressure level (L10) resulting from traffic noise measurements over periods of 1 h and 18 h were given in the greater Amman (Jordan) area.

TL;DR: The parameters that affect flanking transmission are described, and design data necessary for the calculation of flanking path noise reduction is given.

TL;DR: A community noise survey undertaken in a small area of Mexico City is described in this article, where the data was collected at 23 sites for three general time periods during a day and the sampling was done in a quasi-random way within the three time periods and at different dates during February-March 1985.

TL;DR: In this article, the sound transmission loss of a single metal panel obtained with the sound intensity technique and the conventional method have been compared with the theoretical model of Statistical Energy Analysis (SEA) in order to explain small systematic deviations between the results of both experimental methods.

TL;DR: A major source of noise in New Industrialised Countries (NIC) is transportation as discussed by the authors, and the influence of this source on the lives of the community is highlighted from results of surveys in NIC.

TL;DR: In this article, the acoustic equations for the general case of sound wave propagation in circular ducts were derived for the purpose of ICE muffler design, and the exact and approximate methods for solution were reviewed, analyzed and compared for the purposes of designing ICE mufflers.

TL;DR: In this article, the authors measured four rooms with volumes between 106 and 607 m 3 and found no significant change in the absorption coefficient at low frequencies when the amount of diffusing elements in the room is changed.

TL;DR: This method is suitable for cases where the traffic volume on each lane is small, say, not more than 600 veh h −1 , and the average velocity of vehicles is slow.

TL;DR: In this paper, the authors investigated the possibility of using a cone and a certain layer of glasswool as a substitute for the traditional wedge structure for treatment in anechoic chambers.

TL;DR: In this article, the accuracy of the calculation method is examined, taking into account these factors, and also possible errors owing to meteorological and road-surface effects, as well as possible errors due to road surface effects.

TL;DR: The method of contour lines in conjunction with the method of conformal mapping is used for the determination of cutoff frequencies of hollow waveguides with arbitrary boundary cross-sections.

TL;DR: In this paper, the authors dealt with the determination of natural frequencies of transverse vibration of a simply supported pipeline containing flowing fluid, and the results may be of some interest since, apparently, there is an algebraic error that affects the values of the natural frequencies already available in the technical literature.

TL;DR: In this article, a system for the location of sparks within an electrostatic precipitator can be used diagnostically to enable rapid identification of electrically weak spots due to wire or plate misalignments, design features or local defects in construction.

TL;DR: In this paper, a computer model is presented for predicting road transport noise in urban and suburban areas under non-free flowing traffic conditions using empirical expressions developed from field studies made at 204 sites (2448 30-min samples) in Bath.

TL;DR: In this paper, the plate edge is elastically restrained against rotation, and the problem is solved using very simple co-ordinate functions and the Rayleigh-Schmidt technique, and constitutes an extension of a previous study performed by the authors.