Hi William,
i use an Ap on my Ipad called anytunePro+
it connects to backing tracks on my iPad, and it allows me to slow down the speed of the backing track, i use it all the time as a lot of my tracks are too fast for me to start practicing with, i then dial up the speed in small increments which allows me to be able to work to playing at full speed.
Another great function, if i have a blues backing track it allows me to change the major key the track is played in, i’ve used it this year to play ‘Blue Moon’ in 12 different majors keys, to practice playing from memory.
So basically you have the option of slowing down and also changing to a different key.
Anytune Music Slow Downer Home Page