Chacham-
I am quite familiar with the teshuva of R’ Moshe and it is a case in point, he clearly holds that all year round music is not allowed whatsoever, and singing to oneself is – at the least – not allowed if it is someone who sings on a regular basis. He ends off with a note that even according to the ?????? one should not listen to music during sefira (and he conspicuously does not mention the three weeks). But this is clearly not his opinion l’halacha.
What I was pointing out to giggle girl was not that she may not listen to music, I know there are people who attempt to be melamed zchus, and I am not coming to be ???? ??? on klal yisroel. It just happens to be that this is one of the stranger minhagim for which it isn’t easy for anyone who knows the sugya to come up with a legitimate limud z’chus, and that people say ???? ????? is muttar in the three weeks seems quite strange as well.