Acknowledgements

This work was supported by the grant from The National Centre of Research and Development (NCRD) in Poland and European Union under Sub-Measure 1.1.1 of the Operational Programme Smart Growth (PO IR) “Industrial R&D carried out by enterprises” (Fast Track), agreement no. POIR.01.01.01-00- 0528/16-00.The Authors would like to thank the Management of K. Jonscher Clinical Hospital in Poznań, Poznań University of Medical Sciences and the physicians from Department of Pediatric Pneumonology, Allergology and Clinical Immunology of this hospital for their help in recording and description of the acoustic signals. We also thank Angelika Podoła for her help in survey collection.