Does anyone know how to do vibrato on the alto recorder, or any recorder for that matter? I'm rather desperate as my exam is coming up soon.

Thanks!

Most professional recorder players would never use vibrato as the players of recorders have historically not used it. I would suggest not using it either. The only true way to get vibrato on any recorder is the same way as a flute, with varying the velocity of the air stream. As you probably know by now, less air means weak sound and poor intonation (not pretty when used in combination). Playing precisely in tune without vibrato is highly preferred on all recorders.

Agreed. I wouldn't do vibrato on a recorder. But if you really want to, you do it the same way as on the flute.