Marshall Monitor II A.N.C. Wind Noise Due to Microphone Obstruction

To confirm this is the primary cause, inspect the exterior microphone ports on the affected earcup for any accumulation of dust, lint, moisture, or physical debris. The ANC system is highly sensitive to air pressure changes; if the microphone aperture is partially blocked, the feedback loop will over-compensate, resulting in an audible wind or static sound. If the ports are physically clean and the noise remains constant in quiet indoor environments, this indicates a mechanical failure or blockage of the microphone module itself.

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