What is bronchophony?

What is Bronchophony?

Bronchophony is an abnormal increase in the clarity and loudness of voice-generated sounds heard through a stethoscope over the chest wall, indicating underlying lung consolidation or increased tissue density. 1

Physical Mechanism

Bronchophony occurs when normally air-filled lung tissue becomes consolidated (filled with fluid, pus, or solid material), allowing sound waves to transmit more efficiently through denser tissue to the chest wall. 2 In healthy lungs, air-filled alveoli dampen and muffle voice sounds, but consolidation creates a more homogeneous medium that conducts sound waves with less attenuation. 1

Clinical Technique for Elicitation

• Ask the patient to repeatedly say "ninety-nine" or "one-two-three" in a normal speaking voice while you auscultate systematically over the chest wall. 1
• In normal lung tissue, these words sound muffled and indistinct through the stethoscope. 1
• Positive bronchophony is present when the spoken words are heard with abnormal clarity and increased loudness, as if the patient were speaking directly into the stethoscope. 1
• Compare symmetrical locations on both hemithoraces to identify unilateral abnormalities. 1

Related Vocal Resonance Signs

Bronchophony is one of three classical voice-generated sound abnormalities originally described by Laënnec:

• Bronchophony – increased clarity and loudness of normal speech 1
• Egophony – nasal, bleating quality where spoken "E" sounds like "A" (the "E-to-A" change) 1
• Whispering pectoriloquy – whispered words heard with abnormal clarity 1

All three signs indicate the same underlying pathophysiology (consolidation or pleural effusion) but differ in the vocal maneuver used to elicit them. 1

Clinical Significance and Diagnostic Value

• Bronchophony is a specific indicator of lung consolidation, most commonly from pneumonia, but also occurs with atelectasis, pulmonary fibrosis, or pleural effusion with compressed underlying lung. 2, 1
• The presence of bronchophony, along with other consolidation signs (dullness to percussion, increased tactile fremitus, crackles), supports the diagnosis of pneumonia when combined with appropriate clinical symptoms. 3, 4
• The absence of focal consolidation findings (including bronchophony, egophony, or fremitus) significantly reduces the likelihood of pneumonia and may eliminate the need for chest radiography when heart rate <100 bpm, respiratory rate <24 breaths/min, and temperature <38°C. 3, 4

Diagnostic Accuracy Considerations

• Signal power spectral density analysis of vocal resonance sounds shows certain frequency regions are statistically significant indicators of lung consolidation. 2
• However, clinical detection of bronchophony requires examiner skill and experience, as subtle increases in sound transmission may be missed by inexperienced clinicians. 1
• Bronchophony should always be interpreted in conjunction with other physical examination findings, patient history, and radiographic imaging—never in isolation. 4, 5

Common Clinical Pitfalls

• Do not assume that the absence of bronchophony rules out pneumonia, particularly in elderly patients who may present with atypical findings. 4
• Do not confuse bronchophony with transmitted upper airway sounds; ensure the patient is speaking at normal volume, not shouting, which can create false-positive findings. 1
• Do not rely solely on vocal resonance findings to diagnose pneumonia; chest radiography remains the gold standard for confirming pulmonary infiltrates. 5