You might be just forgetting to breathe properly prior to or as you speak into the thing.

I did once and fell into the trap of not breathing when going through tubes surfing. As I got better at surfing, even though they are only smaller waves i hit, as you get better your going through them deeper and longer and i found I was nearly blackiing out when getting to the end of some or going under the falls prior to the end. I had to really think about getting a full breath in before I stood and turned up under one.
Messed with for while too once I got consiuss of it ,cause i breathed water coughed and got drilled without any air in me a couple of times. HAbits catch up.