Low noises (4)
I believe the answer is:
moos
'low noises' is the definition.
The answer and definition can be both related to natural events as well as being plural nouns.
Perhaps there's an association between them I don't understand?
'low noises' is the wordplay.
'low' becomes 'moo' ('moo' can be a synonym of 'low').
'noises' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'moo'+'s'='MOOS'
Can you help me to learn more?
(Other definitions for moos that I've seen before include "Sound of cattle" , "Cows' sounds" .)