Audacity is a really great piece of free audio editing software, also great if you need something for translation/transcriptions, where you need to, say, repeatedly go over a few seconds of a three hour file.
|Find total file length||Ctrl+A (=select all), then look at the number on the bottom right – the ‘End of Selection’ on the Selection Toolbar.|
|Skip back five seconds and keep playing||In Edit > Preferences > Playback change the short time ‘Seek Time when playing’ to whatever you want (say, 5 seconds), then you can repeatedly skip back one small audio section. Note that the audio has to be selected for this to work (hold down the left mouse button and drag along a section of the timeline).|
|Start playing from the beginning of the track||Space bar|