Most of the time we only listen to what we want to hear, but words are stored in the memory and can jump out and be listened to when the time is right.
I use Classical music but only choose to listen to pieces than I enjoy, music for me has to be felt inside, if I can't feel it then I only hear the noise.
So whatever you think is futile because you don't get a response and is only heard can become very important to the listener at another time.
I only wish I had listened to lessons from my Mum when younger instead of just hearing her words