[Auscultation of pulmonary rales, from Laënnec to phonopneumography].

The invention in 1819 of the stethoscope by Laënnec was followed by the first classification of pulmonary adventitial sounds. A number of new nomenclatures based upon acoustic principles have subsequently been suggested. Phonopneumography consists of the recording of respiratory sounds and their breakdown into different harmonics by frequential analysis. Broadly speaking, a distinction is drawn between continuous sounds, including sibilants and rhonchi, and discontinuous sounds, covering crepitations and coarse rales.