# acoustic impedance

In the case of loudspeakers, we know the electrical loudspeaker impedance, which loads the power amplifier as a frequency-dependent resistance, and the acoustic impedance, which counteracts the propagation of sound waves due to material properties.

Acoustic impedance is divided into acoustic field impedance, acoustic flux impedance and mechanical impedance. All three characteristic values counteract the propagation of sound.

The acoustic field impedance or the acoustic characteristic imp edance refers to sound propagation in free space. It is the characteristic impedance of the sound. This is formed from the quotient of the sound pressure and the sound velocity and counteracts the sound propagation.

The acoustic flow impedance refers to the propagation of sound in pipes. It is determined from the quotient of sound pressure and sound flow. Mechanical impedance refers to the mechanical energy required by a loudspeaker diaphragm. This characteristic value is defined as the quotient of force and velocity.