I’m using Audacity for the first time. I’m using a Sony Walkman Professional with M-AUDIO Fast Track Pro interface.
I recorded a stereo track from the cassette source material. In the Audacity file, the pitch is slightly elevated and vocals are a bit sped up a la The Chipmunks. The quality of the Audacity track has lots of crackling.
Did the Fast Track come with software and did you install it?
That’s not necessarily a good thing. The Fast Track should just plug in to the Mac and go. If you configured their software wrong, you could have a mismatch between the Fast Track and Audacity.
Control+Tap or Right-Click the sound file > Get Info. Look down the Info panel to More Info, Sample Rate. What does it say?
Check in Audio-MIDI Setup that the Fast Track is operating at the same sample rate as Audacity.
This page in the wiki might help.
Desktop > Go > Utilities > Audio/MIDI Setup.