Kakapo

Kakapo is an open-source ambient sound mixer. It helps you mix sound clips such as flowing water, thunder, rain, chimes, wind, bonfire, waves, train, cat purring, birds, leaves, fan, a Paris cafe, and a street corner.

You can mix these sounds in the required audio levels to create a relaxing audio experience. Kakapo is available as a desktop program, mobile app, and as a Chrome extension.