I Eat Poetry

Not a poem you can use, but your description of listening to your neighbor reminded me of "Music" by Amy Lowell:

The neighbour sits in his window and plays the flute.
From my bed I can hear him,
And the round notes flutter and tap about the room,
And hit against each other,
Blurring to unexpected chords.
It is very beautiful,
With the little flute-notes all about me,
In the darkness.

In the daytime,
The neighbour eats bread and onions with one hand
And copies music with the other.
He is fat and has a bald head,
So I do not look at him,
But run quickly past his window.
There is always the sky to look at,
Or the water in the well!

But when night comes and he plays his flute,
I think of him as a young man,
With gold seals hanging from his watch,
And a blue coat with silver buttons.
As I lie in my bed
The flute-notes push against my ears and lips,
And I go to sleep, dreaming.