resonance

the quality and increase of sound produced by striking the body over an air-filled structure. If resonance is decreased compared to normal, this is termed dullness and if increased hyper-resonance. Tapping the body, often the chest, to determine the degree of resonance, is called PERCUSSION . An opinion may be formed about the condition of underlying organs, i.e the amount of air present or fluid (e.g. in the lungs) or if there is any enlargement.