Definition - What does Acoustic Impedance mean?
Acoustic impedance, also known as impedance is the ratio of pressure on an imaginary surface in a sound wave to the rate of particle flow across that surface. The term is commonly used in geophysics and when any seismic activities are being carried out. Acoustic impedance is denoted by the symbol “Z” and is the product of seismic velocity and density of a rock through which the acoustic waves travels.
Petropedia explains Acoustic Impedance
Sound waves are at times injected into the earth's surface so as to understand the seismic reflectivity. Acoustic or Seismic impedance controls the sound waves that are reflected back. These reflected waves are seismic energy that reflects only when there are interfaces in the rock. The presence of such interfaces is analyzed and evaluated to determine whether these rock interfaces are due to presence of hydrocarbons or any other sources.
Acoustic Impedance can be represented by the formula below:
I = d x V
Where, d represents bulk density of the rock and V represents velocity at which acoustic or sound waves propagate inside the rock.