Ear equalization protects the middle ear from changes in ambient pressure, which occurs during activities like flying or diving. Swallowing or moving the jaw can help equalize the pressure. However, this passive method is often insufficient for the rapid and significant pressure changes encountered during diving descent. For safe underwater exploration, divers must rely on more active and controlled techniques to manage the pressure differential.
The Need for Equalization
The middle ear is an air-filled space connected to the back of the throat and nose by the Eustachian tube. This tube is typically closed but must open periodically to allow air exchange and maintain pressure balance with the surrounding environment.
When descending, the increasing weight of the water column quickly raises the external pressure acting on the eardrum. This higher external pressure compresses the air inside the middle ear, causing the eardrum to bulge inward.
This pressure imbalance creates discomfort and, if uncorrected, can lead to injury. To restore equilibrium, a diver must introduce air from the throat into the middle ear space through the Eustachian tube. This action counters the compression and returns the eardrum to its neutral position. The pressure change is most dramatic in the first few meters of descent, requiring early and frequent equalization.
Swallowing and Jaw Movements
Swallowing and jaw movements can equalize the ears because of the Eustachian tube opening mechanism. The opening of the tube is primarily controlled by the tensor veli palatini muscle, located in the nasopharynx. When activated, this muscle pulls on the lateral wall of the Eustachian tube, causing it to open.
Swallowing and yawning naturally contract the tensor veli palatini muscle, which allows air to enter the middle ear, often causing a faint “pop” or “click.” Wiggling the jaw or pushing it forward also engages these muscles, offering a passive means of equalization. While effective for slow pressure changes, such as during a flight, the rapid pressure increase during a dive descent demands a more forceful, deliberate opening of the tubes.
Reliable Equalization Methods for Diving
Because passive swallowing is insufficient to overcome the force of water pressure, divers must employ active, forced maneuvers.
The Valsalva maneuver involves pinching the nostrils shut and gently blowing through the nose. This forces air from the lungs into the nasal cavity and up the Eustachian tubes, equalizing the pressure. While it is the most commonly taught technique, performing it too forcefully can potentially cause inner ear damage.
The Frenzel maneuver is a more controlled technique preferred by many experienced divers. This method requires pinching the nose, but the diver uses the tongue and throat muscles to compress a small pocket of air instead of the chest and diaphragm. The air is compressed against the closed glottis, pushing the air into the Eustachian tubes.
Other combined methods exist, such as the Toynbee maneuver (pinching the nose and swallowing) and the Lowry technique (Valsalva combined with swallowing). The goal of all these methods is to equalize before any discomfort is felt, ideally every few feet of descent.
Recognizing and Preventing Ear Barotrauma
Failure to equalize the middle ear pressure results in ear barotrauma, often called “ear squeeze.” Mild barotrauma symptoms include muffled hearing or slight ear discomfort. As the pressure differential increases, the pain can become severe, and fluid or blood may accumulate in the middle ear.
More severe barotrauma can lead to a rupture of the eardrum or inner ear damage. This may cause sudden vertigo, nausea, and persistent ringing in the ears. Prevention is centered on the principle of never diving through pain. If a diver experiences discomfort and cannot equalize after ascending a few feet, the dive should be safely ended. Avoiding diving with a cold, allergies, or nasal congestion is also a safety measure, as these conditions can block the Eustachian tubes and prevent equalization.