Vocal Mimicry is the ability to mimic a person's voice.
This ability allows the user to flawlessly imitate another's voice, to the point where even a long time friend is unable to tell the difference. Users of this ability may have a form of telepathy, as Annabeth Chase said that the Cyclops that caught her in Brooklyn was able to mimic her father's voice without hearing it.
When Percy Jackson, Annabeth Chase, and Tyson the Cyclops arrived on the Princess Andromeda, they hear Luke Castellan down the hall, but can't make out what he is saying. Tyson on the other hand can hear them and unknowingly mimics Luke's voice, as well as the person he was talking with. Annabeth finds this to be very unsettling and tells Tyson to stop, but when he does he shows no signs of knowing what he was doing. When Percy tells him to keep going, Tyson once again copies their voices, only for the group to quickly realize that Luke had found out they were listening in.
Later, when Annabeth is explaining why she dislikes Cyclopes so much, she talk about trying to make it to Camp Half-Blood with Grover Underwood, Luke, and Thalia Grace. On the way, they got sidetracked and were attacked by a Cyclops. He managed to change his voice into that of Luke and Thalia in order to trap them. He even managed to somehow copy Annabeth's father, despite him not being there or knowing what he could sound like. Annabeth thought that the monster had somehow taken the sound of her father's voice right from her mind.
When Festus is knocked out of the sky by Khione, Jason Grace, Leo Valdez, and Piper McLean crash at an abandoned car factory. While Leo goes to fix Festus outside, Jason is attacked by three Cyclopes named Sump, Torque, and Ma Gasket. Once Jason was knocked out, the Cyclopes copied his voice to lure Piper out and capture her. They later copy Piper's voice in order to try to call out any possible third demigod, but Leo saw through the trick and eventually rescued his friends.
When Thalia Grace and Luke Castellan are sent to Halcyon's Mansion by Amaltheia to retrieve Aegis when they hear a clacking sound and see glowing red lights of Leucrotae they hear a voice telling them to come to it. They come to a door and quickly decide to go in. There is Halcyon Green, son of Apollo. He cannot speak so the beasts speak for him in a flawless tone. When Thalia asks if they understand human speech, one imitates her voice perfectly. They are going to eat Thalia and Luke at sunset. However, after getting Aegis, they kill the Leucrotae with Greek Fire. Halcyon gives Luke a dagger, before sacrificing himself to kill the monsters. Soon after being blown out of the house (after a close encounter with an injured Leucrotae), they meet a seven year-old Annabeth and Luke trades her Halcyon's dagger for her hammer.
- Generally, users of this ability have better than average hearing.