Debloisi records an instance of congenital web of the vocal bands.

Mackenzie removed a congenital papillomatous web which had united the vocal cords until the age of twenty-three, thus establishing the voice.

Poore also recorded a case of congenital web in the larynx.

Elsberg and Scheff mention occlusion of the rima glottidis by a membrane.
Instances of duplication of the epiglottis attended with a species of double voice possess great interest.

French described a man of thirty, by occupation a singer and contortionist, who became possessed of an extra voice when he was sixteen.