Here we'll talk about who the flute players were on those 12 special days we mentioned in the previous Mishnah. The Mishnah says, “The flute players were the Kena'ani (Canaanite) slaves of the Kohanim (priests).” This is the opinion of Rabbi Meir. According to him, the fact that a person was allowed to play the instruments in the Beit HaMikdash is not proof that he is Jewish in any way with regard to marriage. So there was no reason to prevent a Kena'ani slave, who was not allowed to marry Jews, from playing in the Beit HaMikdash.
Rabbi Yosei says that the flute players were people from prominent families, from Beit Tzipporiya and another location. They were Yisraelim (Israelites) with very pure, unblemished lineage. According to Rabbi Yosei, they would marry their daughters. The fact that a person played the instruments in the Beit HaMikdash could be used as proof that he was of pure lineage. So the rabbis would not allow a Kena'ani slave to play these instruments; they would allow only a Jew of pure lineage, like these families.
Rabbi Chanina ben Antigonos gave a third opinion: according to him, the individuals who played the instruments were Leviim (Levites). When a person sees somebody playing the instruments in the Beit HaMikdash, he can assume that the person is of pure lineage and also that he is a Levi, eligible to receive the Maaser Rishon (First Tithe). Therefore, according to Rabbi Chanina ben Antigonos, the Leviim were the only ones permitted to play music in the Beit HaMikdash. But everybody agrees that only the Leviim sang in the Beit HaMikdash; there is no Machloket (dispute) about that. They base it on Pesukim (verses) that say explicitly, straight out, that the Leviim were the ones who sang in the Beit HaMikdash. The Pasuk (verse) says that they will minister or work in the Beit HaMikdash like all their brothers, the Leviim, and we learn from here the word Sheret. What does that mean? We say that it's Shirot, that it's about Shir, it's about singing. So the Leviim were the ones who, everybody agrees, sang in the Beit HaMikdash.