Simfly, on the ramp there are many, many sources of noise that combine to produce somewhat of a cacophony. APU whine is no exception and contributes to a 'blanket' of noise that you tend to shut-out automatically if you spend much time in this environment.
Also, any-one who has ever been up-close and personal to an A/C like the BAC1-11 (alas no more!) with or without the hush kits, will attestify to the terrific blast of noise that they are capable of even whilst taxiing, which can drown out almost anything in the immediate vicinity, even another a/c with engine(s) running.
Last edited by DanAir1-11; 30th September 2003 at 20:13.