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1
Akustyka cichych asfaltów
100%
Gołębiewski R.
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tom nr 7
47-49
PL
Najczęstszym sposobem na obniżenie hałasu samochodowego jest zastosowanie ekranów akustycznych. Jest to skuteczna, lecz droga metoda redukcji hałasu. Dlatego coraz częściej stosuje się porowate nawierzchnie asfaltowe, które obniżają hałas toczenia pojazdów samochodowych. Stosowanie tego rodzaju nawierzchni drogowych jest uzasadnione szczególnie w przypadkach, gdy przekroczenie dopuszczalnej wartości równoważnego poziomu dźwięku nie przekracza 5 dB.
2
Content available remote Simple methods for determination of the acoustical properties of ground surfaces
100%
Gołębiewski R.
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tom Vol. 32, No. 4
827--837
EN
The interactions between the sound wave and the ground surface belong to the most important phenomena determining the outdoor noise propagation. In the present study, the exact theory of noise propagation and two simple models of the ground effect are analysed. The paper presents a method of determination of the effective flow resistivity, based on the twochannel measurement of the sound level (the exact theory). For the simplied model of the ground effect, the adjustable parameters are given as a function of the effective ow resistivity. Similarly for the ground effect model given by ISO 9613, the dependence of the ground factor (as a function of the effective flow resistivity) is presented. Additionally, for a few selected types of ground surfaces, the values of the model parameters were determined.
3
Content available remote Railroad noise affected by downward refraction and turbulence
63%
Gołębiewski R. , Makarewicz R.
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tom Vol. 27, no. 2
83-94
EN
For downward ray bending (temperature inversion and/or downwind propagation) geometrical spreading is principally affected by atmospheric turbulence. Additionally, the variations of rolling stock and train speed occur. Thus, the sound exposure level, LAE, changes from train to train and the equivalent continuous A-weighted sound pressure level of railroad noise, LAeqT, changes from day to day. As such, the mean, LAeqT, is important environmental noise characteristics. The simplified model of noise generation and propagation is derived. It makes possible to calculate LAeqT. Two adjustable parameters of the model are estimated from measurements of the sound exposure level, LAE.
4
Content available remote Aircraft noise propagation - the simplest case
63%
Makarewicz R. , Gołębiewski R.
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tom Vol. 27, no. 2
109-116
EN
Geometrical spreading, air absorption, and refraction are the main wave phenomena that govern the propagation of aircraft noise. The results of this study make possible the calculate noise at ground level in terms of the sound exposure level, LAE. The model applies to an aircraft with a nondirectional radiation pattern (e.g., helicopter, one-engine propeller) while the atmosphere is at rest. The derived equations provide some insight into the nature of noise propagation, that can be useful for teaching purposes.
5
Content available The Uncertainty of Noise Composed of Separate Sound Events
63%
Makarewicz R. , Gołębiewski R.
Archives of Acoustics
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2016
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tom Vol. 41, No. 1
133--138
EN
Transportation noise is a main source of noise pollution. It is assumed that it consists of recognizable noise events which come from moving aircrafts, trains and boats. The noise of an isolated sound event is assessed by the sound exposure level, LAE. Much legislation and many regulations and guidelines employ the A-weighted time-average sound level, LAeq,T, with the time interval T of one hour or longer. LAE measurements enable an approximation of LAeq,T. The key point is the uncertainty of this approximation. It has been shown that an increase in the number of LAE categories brings about a decrease in uncertainty. For illustrative purposes, LAE measurements of aircrafts taking off and landing were carried out.
6
Content available remote Verification of two methods of railway noise propagation
63%
Gołębiewski R. , Makarewicz R.
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tom Vol. 34, No. 2
177-188
EN
The noise maps of agglomerations comprise those of road traffic-, tram-, aircraft-, industrial- and railway noise. EU recommends the use of a few selected calculation methods for the estimation of noise: for road traffic noise - NMPB-Routes-96, for aircraft noise - ECAC.CEAC Doc 29, for industrial noise - ISO 9613-2 and for railway noise - Reken en Meetvoorschrijft Railverkeerslawaai 1996 (for tram noise - there is no specific computation method). However, the Member States can use their own computations methods provided that these methods have been positively verified. The results of the calculations using their own method and interim method must be compatible. In this paper, two methods of railway noise propagation are compared: the first one recommended by EU and the second one developed at the Adam Mickiewicz University in Poznań. The results obtained by the two methods are similar.
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