1. Department of Energy Saving and Air Protection, Central Mining Institute, Plac Gwarków 1, 40-166 Katowice, Poland
2. Department of Acoustics, Electronics and IT Solutions, Central Mining Institute, Plac Gwarków 1, 40-166 Katowice, Poland
3. Geoenvironmental Research Centre, School of Engineering, Cardiff University, Cardiff CF24 3AA, UK