Musnad Ahmad 1153:1185

Yahya ibn Adam narrated to us, Ibn al-Mubarak narrated to us, from Ma'mar, from 'Ata' al-Khurasani, from Yahya ibn Ya'mar, from 'Aisha, she said: I said: "Did the Messenger of Allah, peace and blessings of Allah be upon him, raise his voice in recitation?" She said: "Sometimes he would raise it, and sometimes he would lower it."