Inspiron 7548 - Bluetooth Headphone Sound Quality

The sound quality on paired headphones is terrible. There is a background, high pitched whine being transmitted that makes it unbearable to listen.

A wired pair of headphone works fine. The headphones work fine when paired with my Note 4 & Sony TV. A second pair of bluetooth headphones exhibits exactly the same problem, so it is 100% definitely the laptop that is the problem.

Does anybody know how the fix this please?