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.
Roman and Riker (Lab Rats Elite Force) via to shapeshifting
Deimata (Girl vs Monster)
Jacob Pevsner (Lego Ninjago: Masters of Spinjitzu)
Rita Santos (Mako: Island of Secrets)
Lyla (Mako: Island of Secrets)
Nixie (Mako: Island of Secrets)
Zac Blakely (Mako: Island of Secrets)
Merrill Young (Vampire High)
Cleveland Brown (Family Guy)
Zirconia (Sailor Moon SuperS)
Witches (Sabrina, the Teenage Witch)
Discord (My Little Pony series)
Twilight Sparkle (My Little Pony series); via Magic
Starlight Glimmer (My Little Pony series); via Magic
Leslie Meyers (South Park)
Beardo (Total Drama)
Wild Hunt/Siren (Triage X)
Gerald McCloy (Gerald McBoing-Boing)
Forest Dragons (The Last Dragon)
Tom Turbo (Tom Turbo)
Obito Uchiha (Naruto)
Vision (Marvel Comics)
Alex Mercer (Prototype)
James Heller (Prototype 2)
Freddy Krueger (A Nightmare on Elm Street)
Cell (Dragon Ball Z)
A Predator (Predator franchise)
Willow Rosenberg (Buffy the Vampire Slayer)
Aku (Samurai Jack)
Ixis Naugus (Archie's Sonic the Hedgehog)
Suki Sato (Tower Prep)
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 imitade other people's voices and even animal sounds using one of his 111 tricks.