How does one Slow Down Tunes?

In older builds of SRB2, players were simply able to slow down or speed up tunes by typing in "tunes <track#> <speed>", but as of recently, that doesn't seem to work anymore. I always liked to listen to Deep Sea Zone Act 1 slowed down slightly from time to time, it always sounded pretty angelic to me. Did the developers take out this feature altogether, or am I doing something wrong?

Also, sorry if I posted this in the wrong thread, I haven't used this site in literally ages!

Yeah, that particular feature doesn't work in srb2win.exe but it DOES in srb2dd.exe. Apparently SDL2_Mixer just doesn't support that kind of thing according to this post: https://mb.srb2.org/showthread.php?t=40084#2