Wyniki wyszukiwania - BazTech

1

Noise indicators for corona acoustic signal from power lines - estimation in intensified interference conditions

Wszołek T.

Archives of Acoustics

|

2009

|

Vol. 34, No. 1

41-49

EN

In the spectrum of corona acoustic signal two characteristic components can be distinguished: (1) tonal components - higher harmonics of the network frequency and (2) noise component, observed in the frequency band extending above 1 kHz. On the other hand the total intensity of that signal is relatively low - up to 50dB at 15m distance from the outmost conductor - and it is strongly dependent on the environmental conditions. Thus the nature of that signal is essentially random. Because of the above-mentioned features, in practice the best evaluation method of the negative environmental impact is a continuous signal monitoring. Unfortunately for such a procedure some problems are encountered with automated extraction of the parameters (indicators) normally used for evaluation of the signal's acoustic annoyance, especially in intensified interference conditions. One of the more efficient methods of filtering out the random interference signals is the statistic spectrum measurement method. In this work a practical realization is described for estimation of corona noise indicators, making use of the statistic spectrum measurement. High efficiency of such an approach has been shown, especially in favorable weather conditions, when the acoustic signal of corona process is relatively low, while the random interference level may be intensified.

2

The noise-induced harmful effect assessment based on the properties of the human hearing system

Kotus J., Kostek B.

Archives of Acoustics

|

2008

|

Vol. 33, No. 4

435-440

EN

In this paper a new method of assessing noise-induced harmful effects on the human hearing system is described. The method proposed determines the cumulative impact on hearing system produced by the excessive noise taking into consideration properties of the human hearing system. Based on the predicted effects of the noise exposure, the new types of noise indicators are engineered. The evaluation of these indicators employed various types of noise. The indicators proposed can improve assessment of the harmful effect caused by the noise exposure. An influence of the type of the critical band representation of the hearing system (Bark or ERB scales) on the noise indicator effectivness is also discussed.

3

Complex noise indicator for noise mapping based on the EU working groups' and Polish results of the annoyance investigations

Kucharski R.

Archives of Acoustics

|

2007

|

Vol. 32, No. 2

293-302

EN

The Noise Directive 2002/49/EU includes obligations for noise mapping for agglomerations above 250 thousand citizens in the first step and later - above 100 thousand people. The noise map of the city consists of, at least, 4 layers of information. Each layer, in graphical form, represents different kinds of noise distribution, for traffic, railway, air and industrial noise. One can ask how to assess the complex exposure for all noises from all layers of the map? The proposition of the complex index evaluation is developed in the paper. At first, it was assumed that the basic indicator for complex description of the acoustic conditions is the sum of the weighted noise exposures connected with the LDWN level from different category of noise. The weights for the complex indicator were worked out on the basis of the results of the noise annoyance investigations, carried out by the European Working Group on health and socio-economic aspects, published in position papers (year 2002 and later). However, one can ask if the European relation between noise levels and noise annoyance is correct for Polish conditions? In the second part of the paper the results of the comparisons between EU's and Polish annoyance curves are presented. The curves were obtained as the correlation's product of the subjective assessments (query) and LDWN levels measurements and calculations. These investigations in Poland were carried out as a part of the annually project called "Noise Monitoring System" (coordinated by Chief Inspectorate of Environmental Protection). Their background results are characterized in the paper.