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I'm currently designing an advanced alien civilization that has achieved telepathy. The idea is that each one of their species has a small device merged with their brain that can allow them to communicate with multiple other ones of their kind at the same time, no matter how far away they are from each other.
However, the species I'm designing also has a spoken and written language, and there's where the problem begins. If a species has telepathic technology and it's a far better way of communication, then why would they still keep their spoken language?
I've been trying to came up with a reasonable answer but I couldn't came up with something good. So my question is, why would a telepathic species still use spoken and written language?
Edit: I'm making a few edits just so everyone knows. Their species has left behind their natural bodies for biomechanical ones that are powered by an infinite energy source, so the telepatchic devise doesn't draw too much power from their bodies. Also their society is pretty utopic, they don't have some higher goverment leader, they don't have crime and they don't have privacy. Basically there is no need to keep secrets from others. And lastly, the telepathic device is actually part of their biomechanical bodies, so they're sort of born with it.