The dipole speaker principle works with two speakers. Both speakers radiate the sound
in different directions and also work in a phase-shifted manner. One speaker emits the sound to the front, the other to the rear. This technique creates a diffuse sound image, which is used especially for surround sound. Depending on the arrangement of the two loudspeakers to each other, one speaks of the dipole or bipole principle. The latter is the case when the two speakers are arranged in opposite directions. In this constellation, one speaker radiates to the front, while the other radiates the phase-shifted signal
to the rear. Theoretically, no sound would be heard on the axis between the two speakers, as the sound signals from both speakers compensate for each other.
In practice, the sound from the speaker radiating to the rear is reflected by the walls and arrives at the listener with a time delay, causing the diffuse sound impression. Dipole speakers are used in surround systems and are specified in the Tomlinson Holman Experiment (THX).