Or HaChaim on Deuteronomy 27:14/אור החיים על דברים כ״ז:י״ד

1 וענו הלוים, and the Levites will "answer," etc. Actually, the meaning is that the Levites will commence speaking whereas the people will respond by saying "Amen." Onkelos translates the word וענו by writing ויתיבון, "the Levites will sit down." According to Onkelos these words would be in response to the Torah mentioning in verses 12 and 13 that these tribes would "stand" on the mountains to listen to the curses and blessings respectively. Targum Yonathan ben Uzziel translates the word וענו as ויכרזון, "the Levites will proclaim." I find this difficult, seeing the Torah added that they would speak קול רם, "in a loud voice." Why would the word וענו merely duplicate the meaning of קול רם? Perhaps what Yonathan ben Uzziel meant was that not only the recital but also the proclamation should be in a loud voice.