R' Shlomo Aviner takes a strict approach and writes unequivocally that the answer is no (#17 from the top).
סטנדאפ בבין המצרים
ש: מותר ללכת למופע סטנדאפ?
Standup during the 3 weeks: Q: Is one allowed to go to a standup show?
ת: ודאי אסור. אסור כל השנה בגלל מושב ליצים. ע"ז יח ב. קל וחומר בין המצרים
A: Definitely forbidden. [Going ...
Yes, based on The Ari Zal and The RaShaSh you say both tikunnim except on Rosh Chodesh where you recite only Tikkun Leah and Shabbat where you say neither. On Tisha b'Av itself at Chatzos HaLayla we only say Tikkun Rachel.
This is how almost everyone (if not everyone) who merits to say Tikkun Chatzos is noheg.
.כל המתאבל על ירושלים, זוכה ורואה בשמחתה
See this article in this year's Agudat Yisra'el pamphlet, which was reviewed by R. Shmuel Fuerst. On p. 13 it says that music that is not for the sake for enjoyment may be heard during the Three weeks. Among those exceptions is a teacher dancing with young children.
Note that by this phrasing, it implies that not only may a teacher dance with the children, ...
Rav Gormon of Chabad Toronto: recommended to me that until the Hodesh She'hal Bo (ashkenazim) or Shavua She'hal Bo (sepharadim) it is permissible, min ha'din. From that point onward, it would be recommended otherwise, from the mishna's point of משנכנס אב ממעטים בשמחה.
There are sources permitting learning to play an instrument until Rosh Chodesh Av, some even say until Erev Tisha B'Av. Those who permitted playing for real would surely permitting learning about music.
For instance OU writes
Similarly, She’arim HaMitzuyonim B’halacha (122:2) writes that one who
is learning to play an instrument may practice until Rosh ...