What is the ruling on the mumbling/clearing of the throat by those led in prayer (ma'mumeen) or by listeners, out of their belief that it helps the Imam or Khateeb improve his voice and clarity?

Clearing one's throat during prayer without need invalidates it if two or more letters are produced, according to the majority of jurists, unless it is due to a natural excuse or a legitimate purpose such as improving the voice or informing the Imam. As for clearing one's throat during the sermon without need, it is not permissible but does not affect the validity of the Friday prayer.