Headphones or subwoofer heavily suggested.
Here is a pure deep relaxation noise which is great for focusing and getting to sleep. It works best when your speakers have a wide range with a subwoofer or a pair of headphones but this noise one has also been equalized to work with many phones and tablets to some degree. It is also great for aiding in meditations and in drowning out other annoying noises that may be in your current environment.
► Watch on DTube
► Watch Source (IPFS)