A system for monitoring and analysing a change or deviation of sound variables within a closed pressurised unit, which system is a system for distribution of fluid components and which system comprises at least one closed pressurised unit, which closed pressurised unit in turn comprises a flow inducer, at least one device having at least one changeable open area and at least one sound capturing device; a system monitoring device having a database, which database comprises stored reference values for sound variables, which database further comprises values of characteristic variable(s) and/or open area corresponding to the reference sound variables values and which system monitoring device is able to receive values of sound variables and characteristic variables and compare it to the stored values from the database; and a method for monitoring and analysing a change or deviation of sound variables in a system.