Although astronauts can’t hear external sounds in the vacuum of space (there is no “sound” in a vacuum – nothing to transmit vibrations), we can hear plenty of noises inside the spacesuit. Radio headphones crackle with conversations from Houston and the shuttle and station crews. Turning one’s head creates a rustle of communication cables rubbing against the helmet ring. The backpack suit fan blows a gentle breeze from behind the neck. Sound does conduct through the hard fittings of the suit: locking or unlocking a tool from the chest mini-workstation makes an audible click. Latching tethers onto the hip rings, or sliding a power tool into its “holster” on the workstation causes that sliding or tapping sound into the suit. But I don’t recall the suit itself creating sounds: it’s flexible enough to move and bend, and so is not as taut as a drum that might make a noise. The joint motors driving the robot arm are slow-moving and silent, so overall, the predominant impression in the suit is blessed quiet, compared to the constant white noise and clamor of activity and voices inside the shuttle cabin.
Tom Jones, STS-59-68-80-98