start and narrow it. This prevents air from entering the esophagus. They are then further caught in a vicious circle of forcibly making sounds using the small amount of air remaining in the mouth and therefore produce false sounds such "ka!, kya!" for "a", "ki!, kyu" for "i", and "ku!, kyu" for "u," remaining thus unable to produce vowels as a result.
Pharyngeal sounds are similar to these false sounds, in that air enters as far as the hypopharynx and speech is made in a narrow space, false sounds, however, are formed in the innermost part of the tongue using an insufficient amount of air and producing sounds smaller than those obtained through standard esophageal speech.
(3) Anatomical problems
・ If the space of the hypopharynx has been narrowed by surgery, the amount of force used to push air into the esophagus is low, and the amount of air is small.
