Archives of Acoustics, 32, 4(S), pp. 235-245, 2007

Analysis of stochastic acoustical hazards in environment

Wojciech Batko
AGH University of Science and Technology, Department of Mechanics and Vibroacoustics, Al. Mickiewicza 30, 30-059 Kraków
Poland

Renata Bal-Pyrcz
AGH University of Science and Technology, Department of Mechanics and Vibroacoustics, Al. Mickiewicza 30, 30-059 Kraków
Poland

Acoustical assessment of environment, realized on the basis of changes observation held
as part of national environment monitoring for the need of long term noise protection policy
in environment, demands long term average noise level $L_{\textrm{DEN}}$ and $L_{N}$ estimation. The
estimation is based on noise measurement results from all the days in the year, taking into account
day, evening and night times. The basis for correct statistical estimation when the data
is incomplete (time limited monitoring of acoustic environment) is a choice of time sample so
that results gained reflect the mechanism of noise hazard changes that works throughout the
year. It should provide identification of particular event occurring frequency and time relations
between events, e.g. sound extreme value appearance or recognition of periodical changes of
important parameters in uncertainty assessment. Such process demands assumption of particular
statistical techniques related to the assumed model of noise level changes where the
random factor is important and always present. That problem is part of the article. The paper
presents basic analysis of monitored phenomenon by usage of models framing its stochastic
volatility. Important elements of modeling are described, illustrated by examples of yearly
noise data analysis gathered at one of main streets in Kraków. Attention is paid to the analysis
problem with the process periodicity, measurement uncertainty related to the measurement
conditions volatility or time uniformity of the monitored noise processes in view of its internal
causality relations.
They are loaded with random factor whether we assign randomness to noise source volatility,
whole year measurement conduct inability or distortions related to proper sampling of
given field of noise hazards.
Keywords: noise analysis, noise control, noise condition, hipothesis testing in time series analysis.
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