Are you able to listen to music on motzai sabbath lag baomer?
Rav Vosner (Shevet Halevi vol 8 siman 168) writes that since the Poskim write that the prohibition of having a haircut during the Sefira continues until the morning of Lag B’Omer, the prohibition of listening to music would also apply until morning. (Those Poskim who permit a wedding on the night of Lag B’Omer would certainly allow music at the wedding.)
(Although this year (5770), that Lag B’Omer is on Sunday, one is permitted to have a haircut on Erev Shabbos, that is because of Kovod Shabbos, but it doesn’t mean that the general rules of Avelus in the Sefira have ended.)
Nonetheless, it seems to be a prevalent custom amongst many to listen to music on Lag B’Omer night, and it is suggested that since music at weddings is permitted by night, so too any music that is for a mitzvah is permitted, and Lag B’Omer celebrations (and perhaps Melave Malka, this year) may be considered a simchah shel mitzvah.