In Bible times almost all reading was done aloud. Acts 8:30 refers to the evangelist Philip approaching the Ethiopian eunuch. As he approached he heard the man reading the words of Isaiah the prophet, apparently reading aloud to no one but himself.
People in the ancient world assumed that the written word had to be “brought to life” by speech. There was a “community” feeling about written words; books and scrolls were expensive and rare, so the idea of reading silently was an oddity.