[quote name='stevebasshead' post='702625' date='Jan 6 2010, 11:27 AM']As I understand it they don't target specific frequencies, continuous or otherwise, or have I misunderstood? They pick up the ambient sound, phase reverse it and mix it into the signal going to the headphones/buds thus cancelling out whatever ambient noise would otherwise bleed past the phones directly into the ears.
One of the other options I'm considering actually is an ambient mic [i]but phase reversed[/i] to jury rig a noise cancelling set up for him. Depends on a couple of things, whether our engineers desk has a phase reverse switch and balancing the volume level of the ambient mic to successfully cancel out the band noise that's being picked up by the vocal mic.[/quote]
You're correct in what you say but due to the high spl on stage they are not effective enough.... Company I work for looked at building an IEM system with them but it wasn't a goer