The ones I can recommend in that line are the headsets from David Clark.
I've used these for decades in some of the harshest noise locations with
great success. While most of the adaptors I use are home made I suspect that
they can supply one for about any application. They have for me.
regards
Rick
Try noice-canceling aviation headsets (GA or helicopter models have truly
amazing noise suppression). High-end models come with cellphone
interface. I don't think cellphones will work in many data centers, but I
think rigging interface from a normal cordless phone to the headset is
pretty simple.
The better of these headsets (Bose X, Sennheiser HMC460, Zulu Lightspeed,
etc) have additional digital signal processing for getting voice out of
noise - if you don't mind expense:)
--vadim