Hands-free equalization — known as BTV, from the French Béance Tubaire Volontaire — is the ability to open your Eustachian tubes using throat muscles alone, with no need to pinch your nose. For a spearfisher it means a free hand for your gun and your line, and equalization so automatic you barely notice it. This guide explains what BTV is, how it differs from the Frenzel, whether anyone can learn it, the drills to develop it, and the realistic expectations to hold onto.
BTV sits at the top of the skill ladder in our complete guide to freediving equalization. It's a refinement, not a requirement — a solid Frenzel will take you almost anywhere you want to go.
What Hands-Free Equalization (BTV) Is
BTV is voluntarily opening the Eustachian tubes — the same tubes you normally force air through — using the muscles around them, so air flows to your middle ears on its own as the pressure builds. Some people open these tubes by tensing the soft palate and throat, others by a small jaw or swallowing-like movement. The result is the same: your ears equalize without you touching your nose or actively pushing air.
You've felt the tubes open naturally when you yawn or swallow and your ears "click." BTV is learning to trigger that opening deliberately and hold it, so descent pressure equalizes you continuously.
How It Differs From Frenzel
The Frenzel pushes air up a normally-closed tube using tongue pressure and a pinched nose. BTV instead holds the tube open so air passes freely without a push. With the Frenzel you make a discrete movement for each equalization; with BTV the tubes can stay open through the descent, equalizing almost passively.
That's why BTV feels effortless when it works — but it's also why it's less reliable for many divers and harder to force at depth. Most BTV divers still keep a Frenzel in their back pocket for the moments their tubes won't stay open.
Can Anyone Learn BTV?
Honestly: not everyone, at least not fully. BTV comes down partly to anatomy and partly to muscle control. Some divers can do it almost naturally from the start; others develop a partial version with practice; and some never get reliable hands-free equalization no matter how much they train. None of that reflects skill or effort — tube shape and the muscle attachments around them simply vary from person to person.
The encouraging part is that working toward BTV improves your equalization regardless. Even if you never go fully hands-free, the throat awareness you build makes your Frenzel smoother and your tubes more willing to open.
Drills to Develop Hands-Free Equalization
Develop it on dry land, gently:
- Feel the natural open: Yawn slowly and notice the moment your ears click open. Try to recreate just that sensation without the full yawn.
- Soft-palate tension: From a neutral soft palate, gently tense the muscles at the back of your throat as if starting a yawn, and see if you can feel the tubes open.
- Hold the open: Once you find the opening, practise sustaining it for a few seconds rather than letting it snap shut.
- Test under mild pressure: Pinch your nose lightly and gently "suck" — if a tube is open, you'll feel it on the eardrum. This confirms you've found the movement.
Realistic Expectations
Don't make BTV a goal you measure yourself against. It's a bonus skill: lovely when it comes, no loss when it doesn't. A reliable Frenzel already gives you safe, repeatable depth with one free-ish hand, and that's enough for almost all spearfishing.
Build the ladder in order: a confident Frenzel first, then experiment with BTV if your anatomy allows. Either way, the foundation is the calm, early, gentle equalization we cover in the main equalization guide — master that, and your ears will rarely be what ends a dive.
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