Gerhardt's Sound Change

Gerhardt's Sound Change (Gerhard t), a phenomenon consisting of a difference in the pitch of tympanic or metallic percussion sound over cavities depending on the patient's body position. Gerhardt's sound change is found in elongated, oval cavities that are partially filled with highly mobile sputum. In different body positions, the transverse diameter of the oval cavity will be different. With a short diameter of the cavity, the tympanitic sound will be higher than in a cavity with a long transverse diameter. Based on this sign, it was intended not only to diagnose a cavity but also to determine its shape or the position of its long axis in the lung. However, in practice, this symptom is rarely obtained. Furthermore, it should be noted that when changing body position, a change in sound pitch can also be observed over normal lungs due to changed tension conditions of the chest wall itself. Moreover, the opposite phenomenon often occurs; this is explained by the fact that cavities rarely have a proper oval shape; in addition, they are often adherent to the costal pleura, which when the patient's position changes alters the tension of the cavity walls and affects the height of the pulmonary sound.