Words4EV.speak 1.0 (en)

Humming is a very low frequency sound (~40Hz), making its restitution difficult with a conventional audio system. It has a high level, a motor-harmonic behavior and might be discontinuous during acceleration phases. It is oppressive and creates a feeling of pressure on the eardrums, similar to an underwater sensation; it leads to much fatigue. Humming recalls combustion engines and highlights defaults. This is a solid borne noise emitted by one or several panels in the cabin. Humming is similar to the wing flapping of a bumblebee or to "drumming" in its sonority, but less erratic.