If you've not come across this type of 'music' before, you're in for a treat!
When you listen to specially created music through headphones, it can promote a certain physiological response in your body, depending on the frequency.
The word binaural means 'having or relating to two ears'. This represents the process, which works by simultaneously sending a marginally different sound frequency to each ear.
There are many, many tracks out there you can listen to. My intention is to draw your attention to this method of mental preparation for your competitions, so you can explore this for yourself.
For pre-race preparation you would want an Alpha track, perhaps like this one.
For sleep or relaxation, you could try the download track below, which is taken from the Binaural Beats Meditation website.
There are also apps available for smartphones that have binaural beats.