Oomis: Ta’anis Esther, if I recall correctly is to commemorate the three day fasting of the Yidden in Shushan, and the fasting of all the Yidden the day before the want out at war to protect themselves. We fast to memorialize the concept that HaShem is ???? ?????? ????. That’s not really a contradiction to merriment. “
Yes, but Esther Hamalka believed herself to possibly be about to be executed a la Vashti. That was certainly a serious and somber moment, and I personally (again, NOT paskening, this is just my own personal choice on a fast day)don’t feel that of all days, that bedavka on a fast day I have a great need to listen to music. I certainly don’t feel that obligates anyone else, unless there is a clear halacha regarding this.