Donald Murray on voice:
Voice is one of the most complex and yet least-investigated areas of composition. It is a subject that often makes academics uncomfortable because it does not seem intellectual, but we all speak and write with voice. The absence of voice–the personal in writing–is also a voice, the voice of detachment and disinterest that may be appropriate depending on the subject and what the writer needs to say about it.
When you find your voice your writing begins to sound like you. I often read my work out loud to myself to hear the cadence and feel my voice.
Next time I teach voice to a class I think I’ll use this clip to illustrate how comical things can become when the voice is wrong!