Vocal resonance: a narrative review

Physical examination is an important ritual of bedside medicine that establishes a strong bond between the patient and the physician. It provides practice to acquire important diagnostic skills. A poorly executed bedside examination may result in the wrong diagnosis and adverse outcomes. However, the ritual of obtaining a patient’s history and performing a good clinical examination is declining globally. Even the quality of clinical examination skills is declining. One reason may be the short time spent by physicians at the bedside of patients. In addition, due to the substantial technological advancement, physicians often rely more on technology and consider clinical examinations less relevant. In resource-limited settings, thorough history-taking and physical examinations should always be prioritized. An important aspect of respiratory auscultation is the auscultation over the chest wall to detect abnormalities in the transmission of voice-generated sounds, which may provide an important diagnostic clue. Laënnec originally described in detail three types of voice-generated sounds and named them bronchophonism, pectoriloquism, and egophonism. Subsequently, they are known as bronchophony, whispering pectoriloquy, and egophony. A recent variant of egophony is “E-to-A” changes. We searched PubMed, EMBASE, and the CINAHL from inception to December 2023. We used the following search terms: vocal resonance, bronchophony, egophony, whispering pectoriloquy, auscultation, etc. All types of studies were chosen. This review will narrate the physics of sound waves, the types of vocal resonance, the mechanisms of vocal resonance, the methods to elicit them, and the accuracy of vocal resonance.