The changes come at a time of wider reform to the role religion plays in public life under Crown Prince Mohammed bin Salman, Saudi Arabia's de facto ruler, who has eased some strict social restrictions while allowing no political dissent.
It was too early to say for certain how much of an impact the new directive was having on the soundscape in the kingdom. Four residents of the capital Riyadh reached by Reuters on Monday said some, but not all, mosques appeared to have become somewhat quieter. At least one mosque appeared to be broadcasting full-length prayers, as loudly as before.
In a video released by state broadcaster Al Ekhbariyah, Islamic Affairs Minister Abdullatif al-Sheikh said the changes were a response to complaints from the public over excessive volume, including from the elderly and parents whose children's sleep was being disrupted.
"Those who want to pray don't need to wait for ... the imam's voice. They should be at the mosque beforehand," he said, adding that there were also several television channels broadcasting prayers.
Some Saudi Twitter users welcomed a reduction in noise in their areas, though others said they missed being soothed by prayers.
One Saudi user, identified as Mohammad al-Yahya, tweeted: "As long as the reading of the Holy Koran through loudspeakers has been muted on the excuse that it disturbs a few people, we hope that attention is given to a large segment bothered by loud music in restaurants and markets."
Al-Sheikh said some criticism of the policy was being spread by "haters" to cause trouble.
"Enemies of the kingdom want to stir public opinion, cast doubt on the state's decisions and dismantle national cohesion through their messages," al-Sheikh said.