Showing papers in "Applied Acoustics in 1981"

TL;DR: In this article, the authors give guidance to those with particular vibration problems who may ask whether they should be using Statistical Energy Analysis (SEA) and, if so, what expectations they should have of it.

TL;DR: In this article, the authors report that teachers' intelligibility scores deteriorate at (indoor) noise levels exceeding a critical value of 15 dB with regard to a teacher's long-term (reverberant) speech level.

TL;DR: In this article, a statistical energy analysis (SEA) method for calculating the transmission loss for single and double walls is presented, which is based on separate calculations of resonant and non-resonant transmission for frequencies less than the critical frequency, f c, of the panels and calculation of only resonant transmission only for frequencies equal to, and greater than f c.

TL;DR: In this article, the authors presented design charts which enable the total loss factor of walls and floors to be quickly calculated and a comparison with measured results showed very good agreement with the results.

TL;DR: In this paper, it is suggested that a group of four or five objective criteria may be sufficient to characterise the acoustics of a specific hall, and that a rather simple method of ranking is feasible.

TL;DR: In this paper, three types of vegetation can be discerned with regard to the acoustic climate investigated in four different plantations, 2 plant communities, and a grass field, and it was concluded that the sound attenuating capacity of planted vegetations can be used to abate noise pollution in town and landscape planning if the plantations are at least 12 m wide.

TL;DR: In this paper, a corona-type point source suitable for acoustic measurement purposes, especially model studies in acoustics, was described and the characteristics of this sound source were investigated and were found to be very close to those of a theoretical point source.

TL;DR: In this article, experimental studies on reactive types of muffler and their combinations with absorption types were carried out to determine their noise attenuation characteristics and the effect on the performance of the engine itself.

TL;DR: In this paper, it was shown that the temporary threshold shift of hearing due to exposure to noise might be more easily understood if the shifts were considered in terms of the rms pressure rather than in decibels.

TL;DR: The National Physical Laboratory of India (NPL) provided a free space of 3.5 × 3·5 × 5 × 3 ·5 × 2.5 m with a lower cut-off frequency of 70 Hz.

TL;DR: In this paper, a listening experiment with a variety of sounds of equal L A was conducted, and the annoyance due to the sounds was rated by twelve subjects, whose individual ratings show significant agreement.

TL;DR: In this paper, the authors report the results of a series of measurements on different kinds of materials, performed in a reverberation room in both the presence and absence of diffusers, in order to establish the effect of diffusing elements on the absorption coefficient values.

TL;DR: In this article, the authors describe new proposals for measuring the sound power levels of industrial equipment, which are contained in the Noise Procedure Specification NWG-1, issued by the Oil Companies Materials Association, and are intended for use in the petroleum and petrochemical industries.

TL;DR: In this paper, the authors present an exact solution of the title problem using classical beam theory, assuming that the tip mass is guided in such a way that the end of the beam does not rotate.

TL;DR: In this paper, the measurement of noise inside truck cabins presents a series of problems due to several factors such as changes in vehicle's speed, changes in the external environment, variation in the noise level with the microphone location inside the cabin, the window condition (open or closed), etc.

TL;DR: In this article, the authors showed that noise reduction by various shapes of finite barrier can be achieved by applying the Fresnel-Kirchhoff diffraction theory and primarily following the ideas of Maekawa.

TL;DR: In this article, the authors describe principles of modelling traffic noise using an optical scale model, which makes use of light instead of sound, and use it in predicting the equivalent level, L eq, of traffic noise.

TL;DR: In this article, the finite element method was used to determine the eigenvalues of a vibrating, ideal membrane of a cardioidal shape, and it was shown that the results were in very good agreement with values determined by means of an analytical approach.

TL;DR: In this paper, the authors presented calculated and measured sound intensity data describing power flow in near, reflective and refractive acoustic fields, which illustrate how the intensity vectors can show sources and sinks in an acoustic system and how near and far fields are linked together to form a continuous power flow.

TL;DR: In this paper, a simple method of predicting the L eq sound pressure levels in the operator's position for a machine, whilst the latter is still at the design stage, is presented.

TL;DR: The Acoustics Research Laboratory at the Centre for Building Studies, Concordia University, is described in this article, which consists of two coupled reverberation chambers and is designed to permit research investigations of sound transmission, sound absorption and sound power.

TL;DR: In this article, the authors developed an empirical method for predicting the overall sound pressure level (OASPL) at any required location in the cabin of a business executive jet, using a reference spectrum shape corrected for local parameters.

TL;DR: In this article, the walk away method is used to evaluate the room constant, which is a quantity relating to the sound absorption in an enclosure, and is necessary to room acoustics engineering calculations based on the perfectly diffuse sound field theory.

TL;DR: In this article, the attenuation of L eq and L N values with distance over grassland from a line of moving traffic was analyzed and it was shown that the noise sources effectively radiate energy in the horizontal plane with a distance term different from the commonly assumed inverse square law.

TL;DR: How a low-cost micro-computer can be simply interfaced to conventional analogue equipment so as to provide a semi-automated acoustic measurement system is described.

TL;DR: In this paper, a postal social survey with 12 environmental questions was sent to 30 subjects at each of six free and six interrupted flow sites, where 18-h noise measurements were made.

TL;DR: In this article, the results of road traffic noise measurements made in a high-rise city were analyzed and the means and standard deviations of the sound pressure levels within the industrial, commercial, commercial/residential and residential areas were only very marginally different from one another.

TL;DR: In this paper, three case studies of industrial noise control relating to two material-handling systems and a press are presented, each one involves baseline measurements, identification of major noise sources, development and implementation of appropriate design modifications and/or acoustic treatments followed by assessment of their effectiveness.