I am not aware of the EGR valve making any noise as it fails, however the IAC can "honk like a goose"/"sound like a French horn" when it wears out.
Here's what the IAC looks like inside (the solenoid motor is not shown):
The valve plunger is supported and centered on four vanes at the end of its body--I believe that as these vanes wear the valve plunger becomes free to chatter from side-to-side in the bore beneath the valve seat.
When these oscillations reach an amplitude and frequency to which the intake tubing, back through the air box, is sympathetic the whole thing behaves as a wind instrument and produces the rather loud tone I and others have observed.
This process is quite similar to the manner in which a goose or a French horn honks, so it is not surprising that they sound much the same.
There is no fix for this other than replacing the IAC...
- 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum, Delta Force tuned,
Steeda UDPs, Ralco flywheel, RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.
New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq