Unless you explicitly share a voice with another account or to the Voice Library, the voices in your VocieLab are only accessible through your account.
You can activate sharing on individual voices in your VoiceLab. You can share them with specific friends and colleagues, but you can also share your voices with the community via the Voice Library. If you share your voice, you can earn back spent characters when someone uses your voice.
To find out more about sharing, you can read this article here.