Answered by Shaykh Faraz Rabbani
From what little I know, Fajr, Maghrib, and Isha are recited aloud, whereas Zuhr and Asr are recited silently. (Assuming I was praying on my own,) I’ve heard from a Shafi’i Scholar that reading loudly means with a voice that someone close to you can hear, whereas reading silently refers to reading in a voice that you can hear yourself. I was also told that for any salat, it is not enough to simply move your tongue and lips, but you must also recite loud enough for yourself to hear.
I was wondering does this apply to the Hanafi School too?
Also, what’s the minimum level your voice should be when reading Quran or other dua?
If praying alone, one has a choice whether to recite aloud or silently in loud prayers, though the former is better for men.
Reciting silently and aloud are the same in the Hanafi school as the definitions you mentioned above, though there is another valid, though less sound opinion that simply moving one’s tongue and lips is enough. This opinion is strong enough to use to avoid making up past performances. It is better, though, to stick to the stronger opinion for current performances.
The minimum recitation for Quran, invocations, etc, is the same as the minimum quiet recitation in prayer: You need to be normally able to hear yourself.
[Shaykh] Faraz Rabbani
Shaykh Faraz Rabbani spent ten years studying with some of the leading scholars of recent times, first in Damascus, and then in Amman, Jordan. His teachers include the foremost theologian of recent times in Damascus, the late Shaykh Adib al-Kallas (may Allah have mercy on him), as well as his student Shaykh Hassan al-Hindi, one of the leading Hanafi fuqaha of the present age. He returned to Canada in 2007, where he founded SeekersGuidance in order to meet the urgent need to spread Islamic knowledge–both online and on the ground–in a reliable, relevant, inspiring, and accessible manner. He is the author of: Absolute Essentials of Islam: Faith, Prayer, and the Path of Salvation According to the Hanafi School (White Thread Press, 2004.) Since 2011, Shaykh Faraz has been named one of the 500 most influential Muslims by the Royal Islamic Strategic Studies Center.