Egophony

Despite advances in diagnostic imaging and technology, physical examination of the respiratory system remains a cornerstone in the evaluation of respiratory disease. Chest auscultation is a safe, noninvasive, cost-effective technique that often reveals abnormalities associated with common pulmonary conditions. Egophony is an abnormal auscultatory finding characterized by increased resonance and altered transmission of voice sounds heard over the lungs. When a patient is asked to say the vowel sound , the examiner hears a nasal, -like sound, classically described as resembling the bleating of a goat. This phenomenon, also referred to as the  change, reflects an alteration in the timbre of the transmitted voice. Egophony occurs when normal air-filled lung tissue becomes consolidated, compressed, or surrounded by fluid. Under normal conditions, air within the alveoli dampens sound transmission.  In contrast, consolidation or compression of lung tissue alters acoustic properties by selectively transmitting certain sound frequencies. As a result, the lower-frequency components of the spoken vowel are attenuated, whereas higher-frequency components are preferentially transmitted, causing the perceived transformation to an  sound. With pulmonary consolidation, such as pneumonia, the dense inflammatory exudate creates a medium that enhances transmission of higher-frequency sounds, producing egophony over the affected area. Likewise, in patients with pleural effusion, fluid accumulation in the pleural space compresses the adjacent lung parenchyma, thereby altering sound conduction (see Consolidation and Pleural Effusion). Clinicians characteristically appreciate egophony at the upper margin of a pleural effusion, where compressed lung tissue borders the fluid layer. Recognizing egophony allows healthcare professionals to correlate physical examination findings with underlying pathology and supports the timely diagnosis of conditions such as pneumonia and pleural effusion.