Nissin users, is there a way to get the flash units to beep when they are recycled/ready to fire?

I've used the sound on/off button on the Air commander, but all that seems to do is make the flash units beep when you switch modes (i.e. from manual to TTL).

I've read (somewhere) that it can also beep when the unit is fully recycled, but I can't get it to do that.

Anyone know if it's possible?