The antonyms for the word "low-toned" are diverse, depending on the context in which the term is used. However, some common antonyms include "loud," "brash," "strident," "shrill," "high-pitched," and "boisterous." In the context of music, additional antonyms for "low-toned" may include "high-pitched," "treble," or "soprano." In speech, antonyms for "low-toned" may include "bold," "confident," and "assertive." When it comes to general demeanor, antonyms for "low-toned" may include "energetic," "lively," "peppy," and "extroverted.