The user is freely capable of manipulating their voice, allowing them to control their voices to imitate sounds of creatures such as animal noises and explosions or increase or decrease the tone of their voice.
Discord (My Little Pony series) can alter his voice at will.
Twilight Sparkle (My Little Pony series) can also alter her voice via her Magic.
After swallowing a tiny computer, Finn (Adventure Time) can autotune his singing voice on command.
Laughing Octopus (Metal Gear Solid 4: Guns of the Patriots)
Cécile Cosima Caminades (Metal Gear Solid: Peace Walker) can perfectly mimic animal sounds such as bird calls.
Obito Uchiha (Naruto) disguised his voice while wearing his mask, to sound like either his Tobi persona or Madara Uchiha.
The Song Card (Cardcaptor Sakura)
The Voice Card (Cardcaptor Sakura)
In order to trick the senshi, Zirconia (Sailor Moon SuperS) had made copies of himself and duplicated the senshi's mirror images and was able to mimic their own voices in order to stop them.
By changing the flow of gases from their flight bladders, Forest Dragons (The Last Dragon) can imitate the cries of its prey to either avoid drawing attention from prey or lure predators into an ambush.
Tom Turbo (Tom Turbo) can imitate other people's voices and even animal sounds using one of his 111 tricks.
Vision (Marvel Comics)
Clayface (DC Comics)
Black Carnary (DC Comics)
Bobert (The Amazing World of Gumball)
Using the Voice-inator, Doofenshmirtz (Phineas and Ferb) can make everybody's voice higher, making his seem lower by comparison.