This study will compare ultrasound 0.4 W/cm^2 and 100% duty cycle versus no ultrasound
(placebo) for bilateral masseter myalgia in up to 38 adult women. The dose will be applied
for 5 minutes on each side. Both the dose and the starting side will be randomized. Both the
subject and ultrasound operator will be blind to the dose. The outcome measures will be
pressure pain threshold on both masseter muscles and both temporalis muscles, self reported
pain scale (0, no pain to 10, worst pain ever), thermographic temperature of the muscles, and
intraoral temperature. These outcome measures will be taken before and after each dose, so
three times per subject.