hear_intercept is removed in favor of having the things that care register for the COMSIG_MOVABLE_HEAR signal instead.
The signal has been changed to be like the speech one with an args list.
Nanite datums no longer register for the hearing signal just in case, only the voice sensor nanite program does.
Dead code has been removed from to_chat, the savefile/sound checks being just-in-case boilerplate checks made during the conversion to to_chat, the replacetexts sidestepping a byond bug that was fixed in 512.1420.
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