Noise in space: handwaving Moretsu Pirates some
watched Mouretsu Space Pirates 3: noise in space. SEEMS LIKE THE SUCCESSOR TO STARSHIP OPERATORS IS NOT HERE YET
I like handwaving, so let me make an excuse for Pirates here. Actually, two of them. The first excuse is that a certain amount of noise might come through contact with the hull and thus with hull vibrations caused by the various machinery operating. But that's probably not good enough.
The second excuse is that everyone was in what we're told are very automated spacesuits, in an environment with fairly smart computers. People notice and react to sound cues. Thus, there is a good case for generating entirely artificial in-suit noises that correspond to important things going on in the outside world, things like airlock doors opening or potentially dangerous mechanisms in operation that you should steer clear of. So far all of the noises in space we've heard in Pirates have been noises from the ship itself, things that could plausibly be faked in the suits for this reason.
(By the way, I understand why shows love their sliding airlocks but I think it's a stupid design. As I picked up long ago from reading Heinlein juveniles, in theory the safest airlock door is one that opens inwards because then it's essentially impossible to accidentally open it until the inside has been depressurized. If the inside is still under pressure, you have many pounds per square inch holding the door very firmly closed. But inwards-opening doors would not make for good staging and good scenes, so we have the kind of sliding ones that we see in Pirates. This has been your digression of the day.)
More on why the Moretsu Pirates zero-G problems annoy me
For me, Pirates is different from something like Rocket Girls in two ways. First and most important is that the zero-G mistakes in Pirates are so obvious that I've actually noticed them. I am not an alert watcher for technical details; I'm generally happy to get carried away without worrying about the small things (and the zero-G issues in Pirates are a small thing). It takes a fair amount to make me go 'wait, what?' while I'm actually watching the show. Zero-G in Pirates managed.
(I never noticed the zero-G issues in Rocket Girls, for example.)
Second, using zero-G is an actual setting choice in Pirates. Something like Rocket Girls intrinsically requires zero-G; you cannot have a modern era show in space with helpful artificial gravity. But artificial gravity is a common cliche in future space settings and Pirates could have used it without anyone blinking. When an anime does something through choice instead of need I generally hold it to a higher standard.
(For example, if an anime includes a generic camera I will ignore unrealities about it that would irritate me if the anime is clearly trying to show a specific camera but getting it wrong. You could phrase this as 'if you're going to put in details, get them right'.)
PS: note that Author is in fact more technically correct about the situation than I am. He's using the correct technical term 'microgravity', where I've gone for the slightly inaccurate pop culture label 'zero-G'.