The Voice (声), is a mischievous card that is able to steal people's voices. Usually, Voice is content with listening to people, but if it hears a particular voice that it likes, it is capable of stealing it, rendering that person completely mute. Tomoyo becomes victim to Voice's thievery in Episode 37.
The Voice is aligned under Windy.
It's physical manifestation appears as a young pink colored girl with long wavy hair and feather-like ears and arms like wings similar to that of a Harpy. Whether the wings are a part of its dress or are in fact something else is unknown. It wears a rather long dress, and what appears to be a ruff and green brooch around its delicate neck.
Voice is shy and timid and prone to give flight when given to confrontation. Like the Song card, it too has a love of beautiful singing. It is also somewhat greedy, since in order to deliberately prevent the recovery of a lost voice it has stolen, Voice hides where it is very difficult to find.
One sunny spring day, Sakura, Tomoyo and their friends are sat under a blooming cherry blossom tree. The group take it in turns singing. Tomoyo’s is the highlight. The Voice is up in the tree listening. It is only when Tomoyo starts singing does it takes an interest. Tomoyo delights her friends with her serene and beautiful singing voice. The card then resolves to take her voice.
After cheerleading practice one day, Sakura decides to go and listen to Tomoyo during her singing practice. On the way there she senses a Clow Card. The Voice Card appears and rushes into the room and steals Tomoyo’s voice. Tomoyo falls on the floor and the Music Teacher notices and asked her what's wrong. Sakura enters the music room and sees what happened Tomoyo tells her voiceless that she can't speak. Later at night Sakura tells Kero what happened and he explains that the Voice card likes Tomoyo's voice and stole it.
In order to capture Voice and return Tomoyo's voice, Sakura lures it by summoning Song card which sings one of Tomoyo's songs from memory. Sakura seals it after it's initial attempts to flee are prevented thanks to Syaoran and Tomoyo's voice returns back to it's owner.
Voice is one of the group of cards transformed in Episode 53 during Sakura's frantic wave of transformations.