Easy way to track down the noise floor is by running the spectum monitor on the RF or if you have spectrum monitor provisioned on already on controller. below command will help you..
(Aruba) #show ap spectrum ?
ap-list Show list of APs being monitored
channel-metrics Shows channel quality, availablity and utilization
channel-summary Shows channel summary information
client-list Show list of WiFi clients being monitored
debug Show Spectrum Monitor debugging information
device-duty-cycle Shows duty cycle by device type
device-history Show history of non-WiFi devices
device-list Show list of non-WiFi devices being monitored
device-log Show time log of non-WiFi devices
device-summary Shows devices vs channel information
interference-power Shows list of interference power
local-override Spectrum Override Profile (local to this controller)
monitors Show all Spectrum Monitors registered on this
controller
tech-support Display all information for an AP
Show ap arm rf-summary ap-name <name of the ap> will show you the noise floor on each and every AP itself.
Thanks!