breath control

Question
Could you elaboprate on hissing into the regulator mouthpiece. Is this accomplished by closing the airspace in your mouth using your tongue? What happens if you prfer to exhale slowly through your nose, allowing the air to escape through the side of the mask?

Answer
Hi Liam

Thanks for the breath control question.  This is a suggestion I've made several times and I was wondering if you might have read it on an earlier post.  No matter...I'll be happy to explain it further.  I have found that by creating some sort of backpressure against exhaling, I can more easily control my breathing and greatly extend the time it takes to inhale and exhale.  By extending the time for each breath, you can extend the time your air will last.  All of this assumes you are relaxed and not breathing hard.  For me, the hissing is accomplished by placing my tongue against the roof of my mouth and creating a resistance (backpressure) against exhaling.  It also works for inhaling but it creates a vacuum instead of back pressure.  It still feels the same but it's more a matter of terminology.  You can practice this easily and without a regulator in your mouth.  Just place your tongue against the roof of your mouth and breath in and out.  Vary the shape of your tongue to create a comfortable resistance for your own needs.  As long as you're continuing to breathe, you don't have to be concerned with excessive nitrogen or carbon dioxide buildup in your bloodstream or tissues while using this technique.  It will be essentially the same as if you were breathing normally.  Should your carbon dioxide level start to rise, it'll trigger a "need to breathe" response and you'll just relax your tongue to remove the resistance and take a few normal breaths until the urge to breathe relaxes a bit.  As you know, don't hold your breath during this procedure to avoid lung overexpansion problems.

As for exhaling slowly through your nose...you can certainly do that but it will greatly increase fogging problems in your mask.  Exhaling humid air through your nose introduces large amounts of moisture into the mask and it will overpower most antifogging agents in a short period of time.  You'll find yourself putting water into your mask to clear the fogging but it will also wash off the antifog you've applied prior to your dive.  There are some antifogging agents which are applied to a dry mask lens, allowed to dry and then buffed off.  These will resist washing off much better than the wet antifog agents but it's still not a foolproof solution.  It's much better if you can limit the amount of air you exhale into your mask.

Liam, I'm also assuming you're using a standard diving mask and not a "full face" model which encloses both your mouth and nose.  In such a model, you can breath through either your nose or your mouth since the regulator is embedded in the mask and there is no mouthpiece to actually place in your mouth.  But...that's a whole 'nuther question!!

I hope this provides the information your were looking for.  If not, please write back and I'll try again!

Happy Diving!

Mike Giles
Mike's Dive Center
mikescuba.com