framery

That's a very good question. Our ventilation system has an airflow of 900L/minute and our booth's inside volume is 1512L. And because the ventilation is always on, all the air inside the booth is changed every 1,68 minutes or 100,8 seconds. The airflow is also from the ceiling towards the floor so the fresh air hits your nose quite fast.

If you are 1,8m tall and the booth interior height is 2,1m, the volume above your nose is at most 360L, which is removed in 24 seconds.

So I think the answer is 24 seconds.

Anything

I'm not singing about it, so it seems like I care. Karaoke is basically the same thing, no one cares to listen but still they keep doing it.

Quite a few

Go ahead :)