הלכה על מנחות 59:16

Even if one is transcribing from a copy, he must also speak each word out loud before he writes it, in order that he not err (Rashi and Tosafot, Menahot 30), and also in order that the holiness of the breath of reading of each and every word which comes from his mouth is drawn over the words (Ba”h). Only words of admonition need not be spoken aloud (Tosafot, Mordechai).