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nCPAP drivers are valuable devices for neonatal care that may prevent primary mechanical ventilation or re-intubation, but generate a large amount of noise, often higher than occupational limits accepted for adult workers. Therefore, new devices must be designed to minimise this possible noxious exposure of premature infants to unacceptably high noise levels.

ABSTRACT. The first recordings of aco ustic signa ls associated with aval a nches go back to th e 1970s when premonitory low-frequency aco ustic emission was observed in the snow cover just before the setting off of natural avalanches (Sommerfcld, 1977; Sommerfeld and Cubl er, 1983). R ecently, it has been demonstrated tha t avalanches a lso produce strong infrasonic vibra ti ons in air during their m ovement. Th ese in frasoni c vibrations propagate g reat dista nces a nd can follow the natura l relieC It was then a question of automatically detecting this emission to m onitor avalanche ac ti vity, with a view to improving forecasting and assisting in the study of certain asp ects of avalanch e dynamics.With the doubl e aim of pursuing investigations on the m echa nics of the acoustic emi ssion fr om ava lanches a nd designing a n a utom atic detec ti on system , our laboratory has develop ed specific instrumentation, the esse ntial link of which is a n a rray of infrasonic microphones associated with a goni ometer. Sys tem a tic measurem en ts of the infrasonic emissions a re being carri ed out, not onl y of the natural or released avala nches themselves but of a ll events with the aim of characterizing the former in relation to "in frasonic noise".

ABSTRACT. The first recordings of aco ustic signa ls associated with aval a nches go back to th e 1970s when premonitory low-frequency aco ustic emission was observed in the snow cover just before the setting off of natural avalanches (Sommerfcld, 1977; Sommerfeld and Cubl er, 1983). R ecently, it has been demonstrated tha t avalanches a lso produce strong infrasonic vibra ti ons in air during their m ovement. Th ese in frasoni c vibrations propagate g reat dista nces a nd can follow the natura l relieC It was then a question of automatically detecting this emission to m onitor avalanche ac ti vity, with a view to improving forecasting and assisting in the study of certain asp ects of avalanch e dynamics.With the doubl e aim of pursuing investigations on the m echa nics of the acoustic emi ssion fr om ava lanches a nd designing a n a utom atic detec ti on system , our laboratory has develop ed specific instrumentation, the esse ntial link of which is a n a rray of infrasonic microphones associated with a goni ometer. Sys tem a tic measurem en ts of the infrasonic emissions a re being carri ed out, not onl y of the natural or released avala nches themselves but of a ll events with the aim of characterizing the former in relation to "in frasonic noise".