Sennheiser SpeechLine Digital Wireless Series System Documentation page 150

Using the frequency response caps
The MZC 2 frequency response cap enables you to change the sensitivity
of the microphone in the presence range. The MZC 2 gives a treble boost
of 4 dB. Use this cap if the microphone cannot be positioned close to the
mouth, if the sound is too muffled or if you want to increase the speech in-
telligibility.
▷ Slide the MZC 2 frequency response cap over the microphone capsule
until you hear it click into place.
►
An additional frequency response cap (MZC 1) is available as an accessory.
The MZC 1 ensures a treble boost of 2 dB.
▷ Slide the MZC 1 frequency response cap over the microphone capsule
until you hear it click into place.
►
The SL Headmic 1 headset microphone
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