Dear Rabbi Goldstein
I ask if I am permitted to play an instrument like a recorder, piano, etc. in my apartment or anywhere else if men could possibly hear my playing? There is the possibility that neighbors might hear me. Also, if there are men in the same domain, building, house or apartment and the like, am I permitted to play if they cannot see me and I am playing my instrument in another room?
The Poskim write that the Issur of Kol Isha does not apply to a woman playing musical instruments. Thus, you may continue to play musical instruments in your home and you don’t have to worry about men hearing you. [This assumes that one complies with the Sefirah restrictions, and does not play the instruments at times that bothers the neighbors and is accepted for it to be quiet.]
Sources: See Aruch Hashulchan 75:8; Mishneh Halachos 6:25; Minchas Yitzchak 7:70; Avnei Yashpei 2:62; Halichos Bas Yisrael p. 97; Mayan Omer 12:52; Many Sefarim cited in Gan Naul 9:12; See here for the full details of this subject: