Material objects were of value.
Female slave singers were concealed behind an expensive drapery of some sort. The value of music prevailed in the Arabic culture despite "religious and social barriers of the time." The Middle Eastern Arabian culture followed in the foot steps of Persian culture.
Slavery was kept in-tact by Islam as an "ancient Semitic institution."
Possessing a slave with astounding singing abilities was quite valuable. Wealthy men would buy and train female and male slaves to sing and then sell them for a hefty price.
Men would not emancipate their female slaves without marrying her to a man able to provide.
“The Arabian Nights:
A Mirror of Islamic Culture in the Middle Ages”
This article, written
by F. Rofail Farag, can be found in JSTOR.