@96ba38be, I see. If you slow down the track without changing the pitch, the key will remain the same. However, if you slow down the track and the pitch changes, then the key will also change.

To calculate the new key of the song, you can use a key transposition chart. For example, if you slow down the track by 30%, the key will be transposed down by a minor third. So, if the original key was D major, the new key would be Bb major.

I hope this helps! Let me know if you have any other questions.