I found a very (IMHO) interesting text taken from : http://www.paradise-divers.com/reading.htm
What do you think of it ?
It seems to have been written mainly for scuba divers, but is also valid for freedivers, isn't it ?
Middle ear and sinus barotrauma are the most common injuries associated with exposure to increasing and decreasing pressure. Descent in the water adds approximately one-half pound of pressure for each foot of descent and diminishes a similar amount on ascent. According to Boyle's Law, as the pressure increases on descent, the volume of a gas in an enclosed space decreases proportionately. As the pressure decreases on ascent, the volume of the gas increases proportionately. On descent it is imperative that all enclosed air filled spaces be equalized actively or passively. On ascent, the increasing volume usually vents itself naturally.
For equalization to be effective, you should be free of nasal or sinus infections or allergic reactions. The lining of the nose, throat and Eustachian tubes should be as normal as possible. If this is true, the following techniques are effective in reducing middle ear and sinus squeeze.
Prior to descent, neutrally buoyant, with no air in your buoyancy compensator, gently inflate your ears with one of the techniques listed below. This gives you a little extra air in the middle ear and sinuses as you descend.
Descend feet first, if possible. This allows air to travel upward into the Eustachian tube and middle ear, a more natural direction. Use a descent line or the anchor line.
Equalize gently every few feet for the first 10 to 15 feet.
Pain is not acceptable. If there is pain, you have descended without adequately equalizing.
If you do not feel your ears opening, stop, try again, perhaps ascending a few feet to diminish the pressure around you. Do not bounce up and down. Try to tilt the blocked ear upward.
If you are unable to equalize, abort the dive. The consequences of descending without equalizing could ruin an entire dive trip or produce permanent damage and hearing loss.
If at any time during the dive you feel pain, have vertigo (the whirlies) or note sudden hearing loss, abort the dive. If these symptoms persist, do not dive again and consult your physician.
Equalizing Techniques
• Valsalva - increase nasopharynx pressure by holding nose and breathing against a closed glottis (throat);
• Toynbee - swallowing with mouth and nose closed - good for ascent!
• Frenzel - Valsalva while contracting throat muscles with a closed glottis;
• Lowry - Valsalva plus Toynbee - holding nose, gently trying to blow air out of nose while swallowing - easiest and best method!
• Edmonds - jutting jaw forward plus Valsalva and/or Frenzel (good method);
• BTV (Béance Tubaire Volontaire - Voluntary Tubal Opening) - Described by the French doctor Georges Deloncas, the BTV is a hands-free technique mostly used by free divers because it is very efficient even during a fast descent. Deloncas reported that a small percentage of divers (around 30%) are actually able to train their throat muscles to contract and open the Eustachian tubes on demand, as a prolonged action and not a simple spasm. The tubes' shape must be near perfect and a lot of training is required; it is, however, the ideal solution since it frees both hands, is none-forceful and works as well during descent and ascent;
• Miscellaneous - swallowing, wiggling jaws - good for ascent!
Difficulty equalizing the air spaces of the middle ear and sinuses is the most common problem and injury among recreational divers. If you're experiencing problems with equalizing, the first thing to do is consult with your personal physician or an ear, nose and throat specialist who can evaluate your problem. Believe it or not, it may be something as simple as a chronic inflammation from allergies to household plants or pets. The irritation and inflammation resulting from an allergy can narrow the air passages and restrict the flow of air in and out of the middle ear.
Finally, remember to clear before you get into the water. You may also need to simply add something new to your current clearing technique, such as clearing as often as every 1 to 2 feet in order to prevent further difficulty. Make sure that when clearing you do it gently and before the problem becomes severe. Waiting too long will cause unnecessary pain, and a forceful clearing attempt by pinching your nose at that time may cause middle ear damage. Several gentle maneuvers and switching back and forth between swallowing and pinching your nose and gently blowing may be the ticket to a trouble-free dive. Above all, if you cannot equalize, then abort the dive.
What do you think of it ?
It seems to have been written mainly for scuba divers, but is also valid for freedivers, isn't it ?
Equalizing Ears and Sinuses - Problems & Techniques
Middle ear and sinus barotrauma are the most common injuries associated with exposure to increasing and decreasing pressure. Descent in the water adds approximately one-half pound of pressure for each foot of descent and diminishes a similar amount on ascent. According to Boyle's Law, as the pressure increases on descent, the volume of a gas in an enclosed space decreases proportionately. As the pressure decreases on ascent, the volume of the gas increases proportionately. On descent it is imperative that all enclosed air filled spaces be equalized actively or passively. On ascent, the increasing volume usually vents itself naturally.
For equalization to be effective, you should be free of nasal or sinus infections or allergic reactions. The lining of the nose, throat and Eustachian tubes should be as normal as possible. If this is true, the following techniques are effective in reducing middle ear and sinus squeeze.
Prior to descent, neutrally buoyant, with no air in your buoyancy compensator, gently inflate your ears with one of the techniques listed below. This gives you a little extra air in the middle ear and sinuses as you descend.
Descend feet first, if possible. This allows air to travel upward into the Eustachian tube and middle ear, a more natural direction. Use a descent line or the anchor line.
Equalize gently every few feet for the first 10 to 15 feet.
Pain is not acceptable. If there is pain, you have descended without adequately equalizing.
If you do not feel your ears opening, stop, try again, perhaps ascending a few feet to diminish the pressure around you. Do not bounce up and down. Try to tilt the blocked ear upward.
If you are unable to equalize, abort the dive. The consequences of descending without equalizing could ruin an entire dive trip or produce permanent damage and hearing loss.
If at any time during the dive you feel pain, have vertigo (the whirlies) or note sudden hearing loss, abort the dive. If these symptoms persist, do not dive again and consult your physician.
Equalizing Techniques
• Valsalva - increase nasopharynx pressure by holding nose and breathing against a closed glottis (throat);
• Toynbee - swallowing with mouth and nose closed - good for ascent!
• Frenzel - Valsalva while contracting throat muscles with a closed glottis;
• Lowry - Valsalva plus Toynbee - holding nose, gently trying to blow air out of nose while swallowing - easiest and best method!
• Edmonds - jutting jaw forward plus Valsalva and/or Frenzel (good method);
• BTV (Béance Tubaire Volontaire - Voluntary Tubal Opening) - Described by the French doctor Georges Deloncas, the BTV is a hands-free technique mostly used by free divers because it is very efficient even during a fast descent. Deloncas reported that a small percentage of divers (around 30%) are actually able to train their throat muscles to contract and open the Eustachian tubes on demand, as a prolonged action and not a simple spasm. The tubes' shape must be near perfect and a lot of training is required; it is, however, the ideal solution since it frees both hands, is none-forceful and works as well during descent and ascent;
• Miscellaneous - swallowing, wiggling jaws - good for ascent!
Difficulty equalizing the air spaces of the middle ear and sinuses is the most common problem and injury among recreational divers. If you're experiencing problems with equalizing, the first thing to do is consult with your personal physician or an ear, nose and throat specialist who can evaluate your problem. Believe it or not, it may be something as simple as a chronic inflammation from allergies to household plants or pets. The irritation and inflammation resulting from an allergy can narrow the air passages and restrict the flow of air in and out of the middle ear.
Finally, remember to clear before you get into the water. You may also need to simply add something new to your current clearing technique, such as clearing as often as every 1 to 2 feet in order to prevent further difficulty. Make sure that when clearing you do it gently and before the problem becomes severe. Waiting too long will cause unnecessary pain, and a forceful clearing attempt by pinching your nose at that time may cause middle ear damage. Several gentle maneuvers and switching back and forth between swallowing and pinching your nose and gently blowing may be the ticket to a trouble-free dive. Above all, if you cannot equalize, then abort the dive.