Create a new document and then drag an audio file into the top area of the window.
Transcribe Helper documents include a copy of the audio file with the text so after adding audio you can more or delete the original if you wish.
The top of the window is about the audio file you are transcribing.
Default keys for play/pause, speed and back are shown but these can be changed in preferences.
Slow speed ratio controls how slowly the slow speed playback will run. 1 is normal speed, 2 is half speed and so on. You can use fractional increments like 2.5.Home