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1
Content available The Uncertainty of Noise Composed of Separate Sound Events
Makarewicz R., Gołębiewski R.
Archives of Acoustics
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2016
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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.
2
Content available remote Wady i zalety cichych nawierzchni drogowych
Gołębiewski R.
Nawierzchnie Asfaltowe
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2009
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Nr 3
4--6
3
Content available remote Verification of two methods of railway noise propagation
Gołębiewski R., Makarewicz R.
Archives of Acoustics
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2009
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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.
4
Content available remote Changes in the acoustic properties of road porous surface with time
Gołębiewski R.
Archives of Acoustics
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2008
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Vol. 33, No. 2
151-164
EN
The low-noise surfaces such as porous asphalt have become more frequently used to reduce traffic noise. This method of noise control may be effective where reductions of the order of a few decibels are required, and may provide a more economic solution compared to other forms of noise control, such as noise barriers. The main disadvantage of the porous pavement is its decreasing acoustic effectiveness over time, caused by dirt blocking the pores on a road surface. The paper presents the acoustic effectiveness of the two types of porous road pavements after a few years of use.
5
Content available remote Simple methods for determination of the acoustical properties of ground surfaces
Gołębiewski R.
Archives of Acoustics
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2007
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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.
6
Akustyka cichych asfaltów
Gołębiewski R.
Przegląd Komunalny
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2002
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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.
7
Content available remote Railroad noise affected by downward refraction and turbulence
Gołębiewski R., Makarewicz R.
Archives of Acoustics
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2002
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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.
8
Content available remote Aircraft noise propagation - the simplest case
Makarewicz R., Gołębiewski R.
Archives of Acoustics
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2002
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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.
9
Content available remote Vertical distribution of road traffic noise
Makarewicz R., Gołębiewski R.
Archives of Acoustics
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1998
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Vol. 23, no. 4
481-490
EN
Road noise generated by freely flowing traffic is assessed by the time-average sound level, L AT. The noise interaction with the ground surface is the only wave phenomenon that modifies geometrical spreading. A simplified model of the ground effect is applied. The model is founded on the Weyl-Van der Pol solution. Prediction of the time-average sound level, at a perpendicular distance less than 100m and an altitude not exceeding a few tens of meters, requires two simultaneous measurements of L AT at the site of interest.
10
Content available remote Optimization of the duration of an echogram resulting from computer simulation of the acoustic properties of a room
Gołębiewski R., Hojan E., Wojtczak M., Pękala P.
Archives of Acoustics
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1998
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Vol. 23, no. 3
353-362
EN
The authors of this paper investigated the ways to decrease the time of calculating an echogram in the computer simulation of the distribution of the sound field in a room. The authors emphasize the existence of a limiting moment tst up to which the simulation must be completed. The remaining part of the echogram may be treated as a stochastic amplitude (temporal distribution). The authors related the moment tst to the reverberation time RT and the early decay time, EDT, of a room.
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