הַקּוֹרֵא אֶת שְׁמַע וְלֹא הִשְׁמִיעַ לְאָזְנוֹ – יָצָא. רַבִּי יוֹסֵי אוֹמֵר: לֹא יָצָא. קָרָא וְלֹא דִּקְדֵּק בְּאוֹתִיּוֹתֶיהָ – רַבִּי יוֹסֵי אוֹמֵר: יָצָא; רַבִּי יְהוּדָה אוֹמֵר: לֹא יָצָא. הַקּוֹרֵא לְמַפְרֵעַ – לֹא יָצָא. קָרָא וְטָעָה – יַחֲזֹר לִמְקוֹם שֶׁטָּעָה.

One who recites Shema but doesn't make it audible to his ear - has fulfilled his obligation. Rabbi Yosei says: he has not fulfilled his obligation. One who recites but does not articulate each letter properly: Rabbi Yosei says: he has fulfilled his obligation. Rabbi Yehuda says: he has not fulfilled his obligation. One who recites out of order - has not fulfilled his obligation. One who recites and makes a mistake - should return to the place where he made the mistake.