David Weinberger writes, "I just blogged about a 1911 letter in the Thomas Edison digital archive in which the former mayor of Kingston, Jamaica, proposed that Edison take his Gramophone one step further and invent a speech-to-text transcriber. Edison replied, albeit curtly."
The problem you speak of would be enormously difficult I cannot at present time imagine how it could be done.
When Edison chose not to invent speech-to-text tech [David Weinberger/Joho the Blog]