This morning I read that Derrida, in Of Grammatology contests ‘ a tradition of Western thought in which writing has consistently been cast in a role subordinate to that of speech. Whereas speech is habitually associated with reason and rationality […] and the voice is perceived as being closer to the inner ‘truth’ of individual consciousness, writing is considered to be a secondary extension or supplement to the voice, an auxiliary technology employed by human reason but not essential to it. Speech is the guarantor of presence and of authenticity, whereas writing represents artifice and absence, the alienation and deferment of presence.’
Derrida, Johnson, C. NY:Routledge 1999 pp 4-5

Meanwhile, more information about the rolling out of voice in SL including information about how it works can be found here at the voice mentors’ wiki.