Became aware of the sound of many animals (5)
I believe the answer is:
heard
This could be a double definition.
'became aware of' is the first definition.
('hear' can be a synonym of 'become aware of')
'sound of many animals' is the second definition.
'heard' can be an answer for 'sound' (I have seen 'Perceived sound ' mean 'heard' so perhaps 'sound' could also mean 'heard'). I am not sure about the 'of many animals' bit.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for heard that I've seen before include "Traditional children shouldn't be" , "Picked up by the ears?" , "Gathered" , "Received aurally" , "Detected aurally" .)