Showing papers in "Applied Acoustics in 1996"

TL;DR: In this article, it was shown that woollen materials can increase the transmission loss of stud walls by up to 6 dB or more, where their low flow resistivity is an advantage.

TL;DR: In this article, a simple Rayleigh model for sound absorption in a medium made of wood fibres or shavings is described, in which the medium is modelled as a layered structure of parallel slits between which the sound propagates.

TL;DR: This paper considers two versions of diffuse-field theory—the Eyring and Sabine versions—and the prediction of both sound decay/reverberation time, and of steady-state sound pressure level, and discusses applicability with respect to the following room-acoustical parameters.

TL;DR: In this article, it was shown that the screening performance of a single 2 m high barrier on the nearside is reduced by 4 dB(A) when a reflective barrier of similar height is erected at the edge of the farside carriageway.

TL;DR: In this article, a closed-form analytical solution for the sound absorption coefficient of an infinite membrane with an air-back cavity is produced by making a minor modification to the solution for a cavity-backed infinite elastic plate which was derived in the previous paper.

TL;DR: In this article, the transverse vibration of a Timoshenko beam acting on an accelerating mass is analyzed and compared with the corresponding behaviour of a timoshewn beam subjected to an equivalent moving force neglecting the inertial effects of the mass.

TL;DR: In this article, the authors extend their earlier work on developing a low-noise pavement by considering a porous elastic road surface (PERS), and they find that the noise characteristics of PERS are superior to those of a drainage asphalt pavement including the normal absorption coefficient.

TL;DR: In this article, the acoustic behavior of fibrous materials with a flexible frame has been investigated experimentally and the empirical relations between the acoustic parameters and physical values characterizing an internal medium macrostructure have been derived.

TL;DR: In this paper, the authors examined the roadside performance of a multiple edge profile which previous work had indicated would lead to greater noise screening when attached to the top edge of an existing noise barrier.

TL;DR: In this article, a sound-interference-type barrier profile which has been added to an existing noise barrier used for screening traffic noise was modelled mathematically using the boundary element method approach and comparisons were made between predicted and measured insertion losses.

TL;DR: A survey of personal noise exposure has been in progress in Beijing, China, since 1989 and the data on 221 subjects have been collected so far as discussed by the authors, where the main factors that affect the noise exposure of a person are discovered.

TL;DR: In this paper, the active control of vibration transmission in stiffened beams, plates and cylinders, using as control sources piezoceramic stack actuators placed between the flange of a stiffener and the structure surface, has been examined theoretically and experimentally.

TL;DR: In this paper, the authors discussed the calculation of sound transmission loss of a perforated screen at frequencies below 4000 Hz by using a two-dimensional plane wave theory and laboratory measurements from 125 to 4000 Hz and compared the results of theory and experiment.

TL;DR: A field study has been carried out in urban Nigeria as mentioned in this paper, which showed that most urban dwellers consider noise an environmental nuisance, with 65% of all respondents in eight cities feeling highly or moderately disturbed by it.

TL;DR: In this article, boundary element methods (BEM) in conjunction with optimization algorithms are employed for active noise control of sound fields in three-dimensional enclosures, where the total time-averaged acoustic potential energy is chosen as the cost function for the optimization procedure.

TL;DR: In this article, it was shown that attaching small weights to a membrane (called MAW) improves the sound insulation in the low-frequency range without decreasing the light-transmission efficiency of the membrane.

TL;DR: In this article, the authors present the results of investigations of audible noise of high voltage transmission lines of alternating current (a.c. UHV) caused by the corona effect.

TL;DR: A fast adaptive noise control algorithm is presented and applied to the active control of broadband noise in a one-dimensional enclosure that employs the lattice predictor which decouples the filtered reference signals.

TL;DR: In this paper, a method for measuring noise exposure from communication headsets is presented based on an accurate acousto-mechanical model of the human head, and a filter to transform the data from the eardrum level to equivalent diffuse free-field values.

TL;DR: In this paper, the authors analyzed the relationship between noise reduction and the thickness and aggregate size of the drainage asphalt road surface and concluded that the diameter of the aggregate is more important than the thickness of road surface.

TL;DR: In this paper, the effect of DVS on the sound transmission loss of an aircraft panel caused by dynamic vibration absorbers has been analyzed theoretically, where the statistical energy analysis approach is employed where the indirect coupling loss factors are considered in order to overcome the normal deficiency of this method at low frequency.

TL;DR: In this paper, the dynamic Young's modulus and loss factor of typical floor covering materials (felt, cork, solid PVC and PVC foam) have been measured as functions of frequency and strain amplitude in the range of 10 1 to 10 4 Hz and 10 −5 to 10 −2, respectively, in order to clear up the role of material behaviour in the improvement of impact sound isolation.

TL;DR: In this paper, the reflection, absorption, and transmission of the ultrasonic energy at the fabric-water interface were analyzed to determine the fabric processability, which is restricted to only the transmission and absorption of high intensity ultrasound through fabrics.

TL;DR: In this article, the acoustic modal analysis of an axisymmetric loudspeaker interior is carried out using this method and the results are compared with results from the finite element method and experimental results.

TL;DR: In this article, a theoretical model is presented to predict bending wave transmission through double walls where the two leaves are coupled by a line joint. But the model assumes that the joint comprises four semi-infinite plates connected at their edges by an inertialess rigid beam and allows the structural transmission loss between the plates to be computed.

TL;DR: In this paper, a new active noise-control technique for low-frequency sound generated by vibrating surfaces is proposed, which is based on minimizing the volume velocity of the radiating structure within its close proximity.

TL;DR: In this article, a model for the insertion loss of a noise barrier in a refracting atmosphere is presented, implemented in a prediction scheme for outdoor sound propagation up to ranges of 15 km, and compared with numerical simulations of sound propagation over a barrier, using the parabolic-equation method (PE method).

TL;DR: In this article, the authors compared the noise attenuation properties of four military fighter helmets and two headset types against pink noise in an anechoic chamber, and they concluded that a noise level higher than 100 dB in the cockpit is needed for modern fighters and helicopters.

TL;DR: A two-stage conceptual model, consisting of sensory encoding and non-sensory decision-making, provided a reasonable framework for the results and accuracy decreased as the number of speakers increased and their separation decreased, but response time increased with number but was unaffected by separation.

TL;DR: In this article, the equation of motion of a rectangular plate moving over multiple point supports is derived based on the Lagrangian approach and the assumed mode method, where the point supports are assumed to be frictionless and are modelled by linear spring supports of large stiffness with the plate being putted or pushed longitudinally over them.