Have I tried it?

yes - twice - empty on both times - great for singing - the emptiness echoes -

Whilst I was there I was taken short and had to use the loo. Unfortunately, I discovered too late - no @#%&* paper! I remembered my youthful days back in Wales where I used to stand on a street corner selling newspapers. I yelled "SOUTH WALES ARGUS" - and I used the "Echo".

I'd give it a while if I were you.