5. Non-malignant growths of the larynx or trachea.
6. Tumors overlying the superior aperture of the larynx.
7. External compression of the trachea by tumors of the neck or chest.
8. Strictures of the larynx or trachea.
C. Neurotic diseases:
1. Paralysis of the abductors of the vocal cords.
D. Traumatic conditions:
1. Foreign bodies in the larynx or trachea.
2. Impaction of foreign bodies in the pharynx or oesophagus.