The meaning behind "count down"?

[Raiu-Ayu]

yeah I'm pretty sure its about her left ear.

I think she's basically saying that, although she is considered legally deaf, she can still hear a tiny bit in her ear, She knows eventually that she won't be able to hear at all in it, hence a 'count down' of sorts. It also implies that she understands this and accepts it and will continue on.

The line that really interests me is:
"Supposing you are in the abyss
All that is left is to go up"
From this it seems that ayu feels that she has been at the lowest point in her life and so therefore there is nowhere but up from this place.

Despite being quite a sad song, it also has quite a hopeful meaning