For "he speaks low," in French does this mean low volume (softly) or at a low octave (a deep, baritone voice)?
Both actually but I suspect we would be more specific: "il parle très doucement" (softly) and "il parle d'une voix très basse" (deep voice)
I played in a circus band with a group of French musicians once, and there was sometimes confusion created because in English "it's too low", or "play it lower" refer specifically to pitch, whereas "c'est trop bas" or "joue-le plus bas" refer to volume (as opposed to "c'est trop grave").
Similarly, "un haut-parleur" translates as "loud speaker", not "high speaker".
That is definitely correct in English. Sitesurf seems to be saying below that très bas implies quietness rather than pitch, though.
no, "il parle très bas" means he is whispering. if you mean that his voice is deep, you have to change to "sa voix est très grave"
Thank you, sitesurf. I thought I was being smart by going for "He whispers", but it didn't get me anywhere. I have suggested that as a correct answer.
A bit of grammar here: low is an adjective, lowly an adverb. Since it refers to "speaks" it is an adverb and therefore "lowly" is correct and "low" is wrong