ציטירנדיקער פּירוש אויף דברי הימים א 25:7

and the Levites, all who were expert - Heb. מֵבִין. The term expertise (הֲבָנָה) is universally mentioned regarding song, and so above (I Chron. 25:8), when they cast lots, it is written: “like the small one so the great one, expert (מֵבִין) with pupil.” And likewise, (ibid. verse 7): “trained in song to the Lord: every expert (מֵבִין),” and it is written (ibid. 15:22): “And Chananiah, the leader of the Levites, etc., because he was an expert (מֵבִין),” and he was appointed over them to chastise [them] in raising [the voice], how they should raise [their voice], because he was an expert (מֵבִין).

because he was an expert in raising [the voice] in the melody, and the expression of מֵבִין applies to the study of voice. A similar instance is found (below 25:7): “And their number with their brethren, trained in song to the Lord, every expert (מֵבִין) etc.,” and it is written (ibid. verse 8): “and they cast lots, etc.,...expert (מֵבִין) with student.”