All beyerdynamic headsets are optimised for several different applications:
DT 100 series is made for speech and intercom use. These models offer a great speech intelligibility also in loud environments with the dynamic microphones as well as the headphones.DT 200 series has more balanced sounding headphone transducers which allow to judge the quality of an audio signal. In applications with controllable levels around the working space, condenser microphones can shine with their audio quality, in loud environments, the dynamic microphone capsule offers superior off axis rejection. The balanced connection of the microphone also allows long cable runs. These units can be built with a headphone limiter on request for improved hearing protection.
DT 700 series contains the 200 series microphones but combined with extremely isolating headphones for very loud environments.