Extractor Fan noise

3 Extractor fans are installed in the roof of my apartment block to service all 8 units.  They are located directly above my bedroom.  There is a constant humming 24 hours a day and it is especially disturbing at night.  The previous owner of my unit was deaf and therefore this issue has not been raised before.  In spite of mentioning this to other owners and the strata managers no action has been taken.  We are having a meeting next week.   How can I get them to take action?  If the noise has to be measured by an outside source then whose cost is this?