Three sound systems are operated in Masjid al Haram. One is primary and other two are as backup. The Imams right microphone is primary, the middle one is the first backup and the left of the three is second backup.
In the event of the primary sound system failing, the first backup turns on automatically. And if that also fails then second backup turns on, giving Masjid al Haram 0% failure rate. Around 50 staff are behind the sound controls.
More than 6,000 speakers are placed throughout the Masjid al Haram, the courtyards and the surrounding streets and roads, making it one of the largest sound systems in the world.
Each Imam and Muadhin have sound settings set in accordance to their voice and tone, ensuring clarity and balance all around the Masjid al Haram.
Source : Haramain Info