וַיְהִ֤י מִסְפָּרָם֙ עִם־אֲחֵיהֶ֔ם מְלֻמְּדֵי־שִׁ֖יר לַיהוָ֑ה כָּל־הַ֨מֵּבִ֔ין מָאתַ֖יִם שְׁמוֹנִ֥ים וּשְׁמוֹנָֽה׃
And the number of them, with their brethren that were instructed in singing unto the LORD, even all that were skilful, was two hundred fourscore and eight.
Rashi
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).
Rashi
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.”