1. Auscultation of the chest during percussion over the larynx or trachea in cases in which the patient cannot or is not allowed to speak.
2. Auscultation of the chest through the use of nonlaryngeal vibrations in those instances where the subject is unable to talk.

The vibrations are usually induced by gentle tapping over the upper trachea and such vibrations produced by this percussion take the place of those which usually come from the vocal cords.