Jaw movement should not impact your use of hearing aids; however depending on how large of a movement you are making, you might wiggle the hearing aid out of your ear canal slightly, in which case, you might find yourself having to push the hearing aid back into your ear. That said, it sounds as though you have eustachian tube dysfunction and you should consult an Ear, Nose and Throat (ENT) specialist for treatment options.
When the eustacian tube opens and closes, it can have an impact on the percieved volume of sound. When the eustacian tube is closed, speech may sound softer or muffled. When the eustacian tube opens, voices may appear louder. As a hearing aid wearer, having a volume control on the hearing aid would offer a solution to this dilemma. On a side note, if this is a chronic problem and you haven't been evaluated by a physician, you should.
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