Luke, Chewie, the comms officer aboard the Revenge, and this orange lizard/cat thing wear similar headsets in the short. Each consists of headphones with a coronal headband and a microphone on a boom that holds it in front of their mouths.
The only time we see something resembling a control, Luke attempts to report back to the Rebel base. To do so, he uses his right hand to pinch (or hold?) the microphone as he says, “This is Y4 to base.” Then he releases the mic and continues, “He’s heading straight for a moon in…the Panna system.”
Questionable sound isolation
Part of the point of the headsets is to isolate sounds coming through the radio from the ambient noise. But Luke can hear and chat with C-3PO speaking at regular, conversational volumes, so it’s not isolating that much sound. Maybe it’s super-sophisticated noise-cancellation but that’s a lot of credit to give considering the evidence.
Additionally, when Chewie shoots across the bow at the Y-Wing, we hear the artificially-generated weapon-warning noises throughout the cockpit, so it’s a detriment to hide that noise from him. Better would be to have the audio incorporated into the cockpit, which lets him listen for the sounds of the Y-wing around him as well.
It’s not exactly clear that Luke’s touching the mic is an affectation or an actual control. If it was push-to-talk the Revenge wouldn’t have heard anything when he lifted his hands after the callsigns and spoke the actual message. Hopefully it’s not.
The Y-Wing is a combat ship, so it’s questionable to require the pilot to dedicate a hand that could be needed for complex maneuvers for the duration of speech. In fact, it seems to undo much of the benefit of wearing a headset instead of using a handset or something like a handheld CB radio microphone (like Wash’s comm system in Firefly).
A wise design would assign one of those many stay-state toggle switches on the console to keep the channel open and operate by voice activation in maneuver-heavy situations. For more casual conversation, he could switch it back to push-to-talk mode, to avoid accidental noise or interruptions on the channel.
It should be said that a wise pilot needing to communicate with his hands on the yoke might offload this task to the human-cyborg relations droid sitting right there behind him, but you know who am I to question an animated Jedi?
Having the control located at the mic is an intuitive design choice, because it means users can chunk these two things as a single thing in memory: The place for talking. It might seem a little odd because when you speak without a mic you would cover your mouth to muffle speech, but since with the headset you’re speaking with the person “in” the mic, the semantics make sense. The behavior also serves a nice social signal to others in the room to indicate that the speaker is communicating to someone not present (similar to the headset ear-touches in The Fifth Element.)
Questionable mic placement
Having the mic directly in front of the mouth is a poor placement. As sci-fi fans know, speech is air squirted through meat, and putting a mic in the path of that air means the plosive sounds (t, k, p, d, g, and b) can peak out. For audio purists, the proximity effect also means that the proximity of a directional mic to the mouth will over-accentuate and peak the bass responses. But, maybe the Rebels have access to omnidirectional mics that avoid the proximity effect. Still, a better placement to avoid the popping plosives would be just off of the rushing column of squirted air, say near the cheek or chin.
When Luke says “Y4 to base,” it indicates that the system is a radiotelephony model, like the ham radio system. People agree to use radio to speak and listen on pre-arranged channels or sequence of channels, and anyone who knows the channel can lurk and steal important information, like, say, the location of the most wanted Rebel outlaws in the galaxy.
Modern, encrypted, one-to-one communications systems make this seem horribly not-secure, but such systems proved reasonable throughout the World Wars of the prior century. But, even back then there were lots of ways to hedge your bets towards privacy, (like using code or Selective Calling to name just a few) so its absence here is striking, especially since we’ll see in the next review how easy it is to intercept even video messages in the world of The Faithful Wookiee.
That said, extradiegetically, we can cut some slack since they probably aren’t speaking English, either, and both the common and coded Aurebesh have been translated for us.