Final answer:
Over areas of consolidation or compression in the lungs, such as in pneumonia, sounds become louder due to the solidification of lung tissue which transmits sound more effectively than air-filled lungs, resulting in bronchial breathing.
Step-by-step explanation:
Over areas of consolidation or compression, the sound is louder and sounds like bronchial breathing, which is typically heard when a lung or part of a lung becomes solidified due to the accumulation of solid and liquid material in the airway spaces that would otherwise be filled with air. This phenomenon occurs in cases such as pneumonia or atelectasis, and it can be explained by the fact that sound travels more efficiently through denser media. Therefore, within consolidated lung tissue, sound waves, including those of vocal resonance, are transmitted more effectively, resulting in an amplified sound when heard through a stethoscope.
Under normal circumstances, lung tissue is filled with air, which is a poor conductor of sound. However, consolidation replaces this air with fluid or solid tissue, changing the acoustic properties. The sound will not only be louder but can also take on a more hollow quality, resembling the sounds made if one were to speak directly into a stethoscope (egophony).
Comparatively, sound is softer over healthy lung areas because the air-filled alveoli create an acoustic impedance mismatch, leading to the reflection and scattering of the sound waves rather than direct transmission.