Once upon a time, a book on writing introduced be to the concept of 'voice'. Only, that book called it 'Persona'.
Used outside literary debate, the word 'voice' is the sound a human makes when speaking. This is linked to that person only, as much a part of him as his arms or his brain.
On the other hand, the word 'persona' means the role an actor take on. Something which can be changed at will.
I have always thought of the voice as some mask that the writer chooses to put on - perhaps because I have grown up with the persona metaphor.
This woman says the voice is the 'deepest possible reflection of who you are':
http://www.theguardian.com/books/201...ion-meg-rosoff
The comic book artist Herge was kind of middleground here. He felt that the Tintin stories was so much a part of himself, that it would be wrong if other artist continued the series after his death. But at the same time he did employ lots of ghostwriters.