Other: Which headsets to use in high EMI/ RFI enviroments

I have a customer who has an issue with the current headsetstheir spot operators are using where they pick up EM hum from the spot ballastwhen they are using them. I was wondering if you could tell me if any of the Clear-Comheadsets have any type of shielding of the mic element or use a humbucking coildesign? I've had a look at the spec sheet and on the solutions centre, but Ican't find any details other than the element is dynamic.
Answer:
Currently our headsets do not have shielding for the actual mic capsule.Generally for high EMI areas we normally recommend using electret mic headsets.