Basically I would like some idea for passively (i.e. no external power required) amplifying the bird chirping from the garden to inside my room.
Why? I like that sound, also while I'm working, but I live in UK and my room faces north, so even when outside it's spring I keep the window closed otherwise I freeze.
I'm posting the question here because I imagine a solution could involve crafting some kind of funnel to collect and amplify sound and attaching it to the outside of the window... but I'm really not sure about the feasability.