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Cyborg: A Documentary – new film about first upgraded human asks whether we should just because we can.
(theconversation.com)
This is a most excellent place for technology news and articles.
I think generally, assistive devices like Hawking's wheelchair/speech synth wouldn't qualify one for the title of "cyborg", since they're replacing lost/damaged functionality, and didn't grant him any abilities not already available to the average person. Whereas Harbisson's modification is giving him additional abilities that he didn't previously have and are outside of the typical human experience.
Replacing lost functionality is also acceptable for a cyborg, but Hawkings simply didn't replace any organic part of himself, he used external devices. Someone with cochlear implants or a total artificial heart totally should count as a cyborg though - they have integrated mechanical body parts (well, both are partly external I guess...)
But it doesn't really make sense that just because this version of a hearing implant doesn't give you better than normal hearing, having an identical device that did would be the difference between being a cyborg or not.