Learn Tajweed with Yasir Qadhi - The Noble Emissaries (As-Safara Al-Keram)
Episode 17 -- The Silent م
A series about 'tajweed' and the art of reciting the Qur'an
(youtube by : khalifahklothing - here)
Idghaam Shafawai (Idghaam of the Lips) -- when followed by another م, with ghunnah, usually indicated with a shaddah.
Ikhfaa Shafawai -- when followed be a ب, with ghunnah
Idhaar Shafawi -- remaining 26 letters, no special rule