Hi I'm not aware of any online courses. The three organisations I know hold this type of course are Empowering Voices [Empowering Voices](https://www.empoweringvoices.co.uk/), Starfish Project and Mcguire Programme. The Mcguire Programme is international, a business and quite expensive, the Starfish Project is held in the South East of England. [Empowering Voices](https://www.empoweringvoices.co.uk/), this is a charity/non-profit and based throughout the UK. Disclosure time, I am a trustee of Empowering Voices, and help lead the courses. Empowering Voices is 100% led by stammerers who volunteer their time to help stammerers learn a costal breathing technique.