Sennheiser instruction manual Hmec 250 headset

The HMEC 250 headset

The HMEC 250 headset with NoiseGard 2.0 active noise compensation features closed, dynamic, circumaural stereo headphones. The HMEC 250 is a headset for general aviation use.

NoiseGard 2.0

The NoiseGard 2.0 active noise compensation system is based on the principle of cancelling out sound using “anti- sound” (phase-inverted sound). Tiny microphones pick up low-frequency ambient noise (up to 1 kHz) near the ear. The NoiseGard 2.0 electronics use this noise to generate a sound wave which is the exact opposite (i.e.: at the same level but polarity reversed – 180° out-of-phase), the result is that the polarity reversed signal cancels most of the outside noise.

Fail safe operation

When the batteries are completely discharged, the NoiseGard 2.0 active noise compensation automatically switches off. RT traffic (e.g. ATC) and intercom will still be heard through the headphones.

Peak level protection

The peak level protection safeguards your ears from volume peaks above 110 dB.

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