Jet engine startup sounds come from real turbine aircraft, where an auxiliary starter spins the compressor before fuel ignition lets the engine sustain itself. That distinctive rising whine has become a staple sound online for flight simulators, aviation videos and edits that need a believable power-up moment. Creators reuse it far beyond planes, applying it to cars, robots and fictional machines because listeners instantly recognise the spool-up as something huge coming to life.