?????? ??????? - ????? ?????? ????? ?????? ?????????? ??? ??????? ????? ??? ?????? ??????????.??? ?? ??????? ????????? ?? ??? ???????? ?? ??? ????? ??????? ?????? ?? ?????? ??????? ?????? ??????? ??????? ???????? ??????? ????????.Sounds may be electromagnetically or thermally produced, that may be decreased by decreasing the functioning temperature