8 – Dancing and Musical Instruments

Since the custom is not to celebrate too much during the Omer period, the Acharonim write that one is forbidden to engage in optional dancing [as opposed to dancing for the sake of a mitzvah] (M.A. 493:1). They also forbid playing or listening to musical instruments.
According to Sefardi custom, the laws of mourning last until the morning of the 34th of the Omer. Nevertheless, in honor of Rabbi Shimon bar Yochai’s Hillula (festivities marking the day of his passing), music and dancing are permitted on the 33rd (Lag) of the Omer. Afterwards, however, the prohibition [resumes and] continues through the night of the thirty-fourth, until the next morning, when all customs of mourning expire.
According to Ashkenazi practice, the prohibitions last until the end of the 32nd day of the Omer, meaning that music, dancing, and rejoicing are permitted from the beginning of the night of Lag B’Omer, in honor of R. Shimon bar Yochai’s Hillula. Most Jews of Ashkenazi descent refrain from large celebrations – like gala evenings of dance – until the holiday of Shavu’ot, but one may play and hear musical instruments. It is also permissible to hold aerobic classes, because their main purpose is to provide exercise, not joyous dancing. ¹ the weekdays therein; 2) the fact that [so many] tragedies befell the Ashkenazi communities during these days. The only difference is that we are more rigid in our observance of these customs before Lag B’Omer than we are afterwards. All this was already explained above, in sections 2 and 4, and in footnotes 2 and 4.
The distinction between a great or large celebration and a regular one is undefined. However, organizing an optional evening of dance is certainly a large celebration. On the other hand, aerobic classes, which are mainly for the purpose of exercise, are permitted. Regarding [other] joyous events, about which one is unsure whether it is considered a great celebration, one may act leniently if one combines it with a siyum (the completion of a Talmudic tractate) or some other mitzvah component. Sefardim are permitted to participate in any type of celebration [after Lag B’Omer]. If many members of a group [organizing an event] are Sefardic, [the group as a whole] may be lenient, in accordance with their custom, but it is preferable to combine [the event with] a siyum or some other mitzvah. ]
The custom is to allow music and dancing on Chol HaMo’ed Pesach, because we are commanded to rejoice on these days (M.B. 529:16; see Piskei Teshuvot 493:6). Weddings, however, may not be held on Chol HaMo’ed, because we do not mix one celebration with another (S.A., O.C. 546:1). The Rabbis also forbid one to take a haircut on Chol HaMo’ed, to ensure that people do so prior to the holiday (ibid. 531:2).
A Jew who makes a living playing music may perform at non-Jewish affairs, [if] he needs the income. It is also permissible to teach or learn music during Sefirah, since these endeavors are not joyful (Siddur Pesach KeHilchato 12:16; see Piskei Teshuvot 493:4). However, a music student who, in any event, studies intermittently throughout the year should schedule a break, if possible, during the mourning period of the Omer. And if he intends on taking only one break a year, it is preferable to save it for the Three Weeks (see below, 8.2).