|Owner||Earl of Lemongrab|
|Introduced in||"You Made Me"|
|Last appearance||"Mystery Dungeon"|
The Sound Sword is a weapon used by the Earl of Lemongrab in "You Made Me." It produces a strong sound wave capable of knocking out its target. It also has the ability to inflict damage to weak objects; Lemongrab exploded Blombo's headphones and Finn's hat using the Sound Sword. He also shaved off Ice King's beard by the strong impact of his sound sword in "Mystery Dungeon." Lemongrab uses the Sound Sword to render his "unacceptable" subjects unconscious, so he can drag them into the Reconditioning Chamber. According to lead character designer Andy Ristaino, the Sound Sword is powered by the frequency of Lemongrab's screams, hence the "tuning fork" shape and the fact that Lemongrab always screams as he uses it.
The sword is long, flat and yellow and it has an edgeless, forked tip similar of a tuning fork. When unsheathed, the sword has a yellow aura surrounding it. When the Sound Sword's power is used, it emits circular soundwaves at its target.