AudioStretch, the free app of the day could be useful if you don’t already have another app like AnyTune Pro+
I am especially intrigued by this statement – ”
Transcription made Simple
Change the speed of audio files without changing the pitch. Freeze it at zero speed to work out tricky chords and solos. Transpose to any key.”
Plus they give you a keyboard/spectrum to help you transcribe…. hmmmm…..