The CUT 60 is inserted between the capsule and the microphone amplifier.

It prevents the effect of infrasonic disturbances from being passed on to any succeeding device. In particular, pressure-gradient transducers (directional microphones) produce very high infrasonic signal levels when exposed to wind or in elastic suspensions. These can saturate an input transformer or an amplifier stage even before the audible portion of the disturbance becomes noticeable.
To avoid this, a very sharp (24 dB/oct) infrasonic filter at 60 Hz is permanently engaged. It has no effect on speech.