Dosu Kinuta uses the Resonating Echo Speaker worn on his arm to generate powerful sound waves. The Speaker amplifies sounds from the arm's mere movements, but can make even louder sounds if the Speaker is physically struck. Dosu can direct the sound waves based on how he moves his arm, or he can guide them at a specific target using his chakra; because it's sound, it can't be blocked. The sound damages his target's semicircular canals, throwing them off balance so that they can't stand, move, or fight. Additional side-effects include bleeding ears, distorted vision, and vomiting.
Chōji Akimichi attempts to defend himself from this technique by tucking his head into his expanded body, effectively plugging his ears. This ends up making things easier for Dosu: because most of the body is composed of water - which is a naturally good conductor of sound - Dosu is able to further amplify the sound waves by emitting them directly into Chōji's body, assailing his hiding ears. Dosu does something similar against obstacles, focusing the sound waves against them through physical contact in order to decimate them.