One should make sure to learn Torah out loud. If one learns out loud, one will be blessed to remember one's learning. - Eirvuin 54a, Rambam (Talmud Torah 3:12), Shulchan Aruch YD 246:22, Kitzur Shulchan Aruch 27:5. Chida in Petach Eynayim (Eruvim 54a) writes that as the pasuk in Beresheet 27:22 הקל קול יעקב one קול, voice, is spelled complete and one is complete without a vav, to indicate that when we pray we silently and when we learn we learn aloud.
Bruria, the wife of Rebbe Meir, was passing a student who was studying silently without verbalizing what he was learning. She rebuked him and said that his manner of study was incorrect because the verse states, “Life comes to the one who comes upon them” which is meant to be understood as, “life comes to the one who articulates its words with one’s mouth.” - Eruvin 53b-54a
When one learns one should learn out loud but itRav Ovadia Yosef in Halichot Olam (8 pg 390) and Anaf Etz Avot (Avot 3:3). Interestingly, the Maharal (Derech Chaim Avot 3:6) writes that when learning with someone else, such as a chevruta, one is forced explain the issue in words in order to discuss it. In this manner, one accomplishes the an awesome fulfillment of learning Torah which is spoken aloud. However, when one learns alone, even if one says the words aloud, primarily it is a mental thought process and the words are insignificant, which is a lower level of learning Torah.’s considered Talmud Torah even if one only thinks about it.
Seemingly, one should learn aloud. But is that only for Gemara/Chumash/Anything in Hebrew? Or does that mean to say, regardless of what one is learning, he should always learn aloud?