Kindly refer to the following link(s):
Can we pray the voluntary prayers aloud?
Making dhikr, dua, reciting Qur'an & Praying without moving your lips & tongue
Why do we pray Dhur and Asr silently?
Why do we pray Fajr, Maghrib & Isha aloud and Dhuhr & Asr silently? | Sheikh Assim Al Hakeem