There are tons of communication headsets, such as those found in Aliens. These are mostly off-the-shelf varieties and don’t bear a deep investigation. (Though readers interested in the biometric display should check out the Medical Chapter in the book.)
Besides these there are three unusual ones in the survey worth noting. (Here we should give a shout out to Star Wars’ Lobot, who might count except given the short scenes where he appears in Empire it appears he cannot remove these implants, so they’re more cybernetic enhancements than wearable technology.)
In Gattaca, Vincent and his brother Anton use wrist telephony. These are notable for their push-while-talking activation. Though it’s a pain for long conversations, it’s certainly a clear social signal that a microphone is on, it telegraphs the status of the speaker, and would make it somewhat difficult to accidentally activate.
In the Firefly episode “Trash”, the one-shot character Durran summons the police by pressing the side of a ring he wears on his finger. Though this exact mechanism is not given screen time, it has some challenging constraints. It’s a panic button and meant to be hidden-in-plain-sight most of the time. This is how it’s social. How does he avoid accidental activation? There could be some complicated tap or gesture, but I’d design it to require contact from the thumb for some duration, say three seconds. This would prevent accidental activation most of the time, and still not draw attention to itself. Adding an increasingly intense haptic feedback after a second of hold would confirm the process in intended activations and signal him to move his thumbs in unintended activations.
In Back to the Future, one member the gang of bullies that Marty encounters wears a plastic soundboard vest. (That’s him on the left, officer. His character name was Data.) To use the vest, he presses buttons to play prerecorded sounds. He emphasizes Future-Biff’s accusation of “chicken” with a quick cluck. Though this fails the sartorial criteria, being hard plastic, as a fashion choice it does fit the punk character type for being arresting and even uncomfortable, per the Handicap Principle.
There are certainly other wearable communications in the deep waters of sci-fi, so any additional examples are welcome.
Next up we’ll take a look at control panels on wearables.