Quotient of the complex amplitudes of acoustic pressure and acoustic flow (acc. DIN 1320). The acoustic impedance describes the acoustic behaviour of a component. For hydraulics this quotient comprises the dynamic pressure element (changing pressure) and the dynamic flow rate element.
The column of fluid has resistive behaviour, if the internal damping is ignored (acoustic impedance only has a real element). The acoustic impedance of a column of fluid in a pipe is dependent on the termination of the pipe (open, closed, regulated) and, along with the resistive element, also comprises a capacitive and inductive element. Freedom from reflections in a pipe is achieved if the acoustic impedance of the pipe termination is the same as the impedance of the pipe (fluid + pipe walls). The acoustic impedance is used in hydraulics in particular for the design of pulsation dampers.