Percuss means gently tap. This is a part of examining the condition of organs in thorax or abdomen.
The purpose of percussion in the liver is to measure its size. A normal liver makes a dull(consolidated) sound. A dull sound indicates the presence of solid mass(dense areas) under the surface, which is normal. Dullness indicates borderline of the liver and hence find its length.
A hollow and air filled region beneath sounds resonant.
A hyper-resonant is heard on region where it is hyper-inflated with air
Flat or extremely dull sounds are normally heard over solid areas such as bones.
