Was Silent Reading Unusual During Augustine's Time?

Augustine's observation that his mentor Ambrose read silently in the 4th century suggests that silent reading was an unusual practice during that time, implying that reading aloud was the norm in classical antiquity. Scholars like William A. Johnson and Alberto Manguel have examined Augustine's account as evidence that the shift from oral to silent reading was a gradual historical development, with silent reading being a notable exception rather than standard practice in the ancient world.