I recently came across an amazing web site through which you can listen to a huge choice of relaxing sound effects, designed to help you work or concentrate or relax. There are literally hundreds of sounds, based on folk instruments, water and weather, nature, choirs and chants, and loads more. And they're free to listen to for non-commercial use, although you're limited as to how many you can play in quick succession.

Turn up your speakers or put on your headphones and head to https://mynoise.net/ for some great sounds.