ASYMMETRY OF RESPIRATORY SOUNDS AND THORACIC TRANSMISSION

Breath sounds heard with a stethoscope over homologous sites of both l ungs in healthy subjects are presumed to have similar characteristics. Passively transmitted sounds introduced at the mouth, however, are kn own to lateralise, with right-over-left dominance in power at the ante rior upper chest. Both spontaneous breath sounds and passively transmi tted sounds are studied in four healthy adults, using contact sensors at homologous sites on the anterior upper and posterior lower chest. A t standardised air flow, breath sound intensity shows a right-over-lef t dominance at the anterior upper chest, similar to passively transmit ted sounds. At the posterior lung base, breath sounds are louder on th e left, with a trend to similar lateralisation in transmitted sounds. It is likely that the observed asymmetries are related to the effects of cardiovascular structures and airway geometry on sound generation a nd transmission.