Voice generated sounds can provide important clues about respiratory abnormalities. Normal lungs are filled with air, and air does not transmit sound readily. Normally, transmitted voice sounds are difficult to hear – spoken words are muffled and indistinct and whispered words are usually not heard at all. However, when substances such as fluid or solid masses replace air in the lungs, sounds are transmitted more clearly. The sounds that can be assessed are:
- Whispered pectoriloquy: Ask the patient to whisper a sequence of words such as “one-two-three,” and listen with a stethoscope. Normally, only faint sounds are heard. However, over areas of tissue abnormality, the whispered sounds will be clear and distinct.
- Bronchophony: Ask the patient to say "99" in a normal voice. Listen to the chest with a stethoscope. The expected finding is that the words will be indistinct. Bronchophony is present if sounds can be heard clearly.
- Egophony: While listening to the chest with a stethoscope, ask the patient to say the vowel “e”. Over normal lung tissues, the same “e” (as in "beet") will be heard. If the lung tissue is consolidated, the “e” sound will change to a nasal “a” (as in "say").
Bickley, L. S., Szilagyi, P. G., Hoffman, R. M., & Soriano, R. P. (2021). Bate’s Guide to Physical Examination and History Taking (13th ed.). Wolters Kluwer Health: Philadelphia.