Passenger jets produce various noises that can disrupt sleep, including wind, engine, and passenger sounds. Smaller aircraft tend to be louder due to less effective noise separation and minimal soundproofing to reduce weight. The discussion highlights that even larger jets, like the Airbus A340, may not provide a significantly quieter experience for a single passenger. Participants shared personal experiences with noise and vibrations from control surfaces in different aircraft, noting how these factors can affect comfort. Overall, the consensus is that noise levels on commercial flights can be surprising and often hinder the ability to sleep.