Its has to do with the flexibilty of your ribcase and intercostal muscles which coordinate together with the diaphragm the pressure around your vocal cords. Do you know the worldfamous Del Ferro method? It cured my stammer once and for all. I had the same issue with loudness and less fluency. But now It doesnt matter if I talk loud or not. I am completely cured. Follow the science! [Del Ferro method] ([stuttering-delferro.com/the-method](stuttering-delferro.com/the-method)) Science-based Neurologist Dr.J.C.J van Hemert was the first to test Len del Ferro’s hypothesis in 1978. Neurologist Van Hemert’s scientific research shows, using X ray among other resources, that the diaphragm makes uncontrolled movements during stuttering. The air flow is severely disrupted, with the result that exhaled air passes by the vocal cords in fits and starts. Speaking with stutters is the result. Since then several times, scientifically, it’s concluded that The Del Ferro Method can solve stuttering effectively. Among neurologist Dr. M.P.A.M. de Grood (1915-1995) of the St. Elizabeth hospital, Tilburg. Also professor Peter T. Macklem (1931-2011) of the McGill University in Montreal, Canada, one of the most renowned specialists in the field of lung physiology and the diaphragm, confirmed the conclusion of Del Ferro. Under the leadership of Macklem thorough research is carried out for three years among the Erasmus hospital of the Free University in Brussels and in the Clinica Del Lavora in Pavia (Italy). He examined for instance the air pressure against the vocal cords, which is pressed by the diaphragm against the vocal cords. The conclusion was that when this air pressure/ stream is fluent, it’s impossible to stutter. The results of this research are published for instance in the well known scientific journal of the Thoracic society, shown below. Several health insurance companies have tested the effectiveness of The Del Ferro Method over the years. For the reason that the results turned out to be cost effective, health insurance companies moved over to reimbursement of this method.