In the following section the patterns of lung sounds presented will be illustrated from actual tracings of patients with lung diseases who have been recorded using a multichannel lung sound analyzer, Stethograph or STG for short. This device collects data from 16 channels simultaneously. Microphones can be placed on the patient’s chest in a variety of configurations, but for simplicity the patterns seen in common lung diseases are presented with the placement shown below.

Fourteen electronic stethoscopes are incorporated in a foam back pad shown here. A disposable, fluid impervious covering covers the pad during patient application. One microphone is applied on the trachea and one on the heart. Patients comfortably lie on the back pad during recording. Following the recording the computer automatically calculates crackles and wheezes and displays their location on the chest as well as their timing in the respiratory cycle.