Reduction in the intensity (loudness) of breath sounds is more commonly described as reduced ‘air entry’. It can be generalised or localised. Causes of generalised reduction in intensity of breath sounds include obesity, hyperinflation of the lungs (e.g. COPD) and hypoventilation (e.g. life-threatening asthma) etc. Causes of localised reduction in breath sounds include bronchial occlusion (preventing air entry into a lobe), a collapsed lung or lobe, pleural effusion or pneumothorax (causing reflection of the sounds) and unilateral paralysis of the diaphragm or intercostal muscles (causing reduced ventilation) etc. [1]
Bronchophony, also known as bronchiloquy, is the abnormal transmission of sounds from the lungs or bronchi. Bronchophony is a type of pectoriloquy (the increased resonance of the voice through the lung structures, so that it is clearly audible using a stethoscope on the chest. It usually indicates consolidation of the underlying lung tissues. Types include egophony and bronchophony). The patient is requested to repeat a word several times while the PT auscultates symmetrical areas of each lung.
Normally, the sound of the patient’s voice becomes less distinct as the auscultation moves peripherally. Bronchophony is the phenomenon of the patient’s voice remaining loud at the periphery of the lungs or sounding louder than usual over a distinct area of consolidation, such as in pneumonia. This is a valuable tool in physical diagnosis when auscultating the chest.
Bronchophony may be caused by a solidification of lung tissue around the bronchii – which may indicate lung cancer – or by fluid in the alveoli, which may indicate pneumonia. However, it may also have benign causes, such as wide bronchii. As such, it is usually an indication for further investigation rather than the main basis of a diagnosis. [2]
For more on assessment of breath sounds including digital recordings of normal and abnormal breath sounds, I recommend this link.
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