Amplitude Panning

Amplitude panning is a system that transforms both the phase and amplitude differences of a signal recorded by stereophonic reception systems into amplitude differences reproduced by two speakers. These stereophonic reception systems are usually microphone stereo pairs or human ears. This is the basis of several multi-loudspeaker configurations. To start, this system derives from stereophony; Blumlein originally created around 1930.

Amplitude Panning: Techniques

Amplitude panning involves a couple of techniques. Pairwise amplitude panning and vector base amplitude panning are the most common ones. 

Firstly, pairwise is based on the tangent law of trigonometry. It is an essential part of traditional horizontal configurations. These settings have attached speakers that reproduce amplitude differences. Within this type of panning, a set of speakers—equidistant from the listener and located in different positions—generate an identical sound signal. When both speakers are at the same level, a virtual sound source will emerge from the centre.

This virtual source of sound will gradually shift towards the higher output speaker as the differences in amplitude increase. The user will be able to achieve the best directional output when the actual location of a speaker is the only source that generates sound. This happens because virtual sources will be less defined.

Secondly, vector-based a is a technique that positions virtual sources in random 2D and 3D loudspeaker setups. These setups might have speakers above or below the level of the human ears. This arrangement is typical in places such as concert halls, cinemas, and theaters. In these scenarios, listeners require triple-wise panning. Triple-wise panning refers to the use of triangle loudspeaker setups that help with the reproduction of virtual sources. 

In addition, 3D loudspeaker setups are not very effective for amplitude panning reproduction. The reason is that a generalized tangent law cannot calculate panning from random speaker locations or for spherical coordinates. Because of this, it’s essential to use a generic reformulation of the tangent law. This reformulation defines panning with vector bases, as well as the positions of virtual sources using directional angles. Sometimes the same signal reproduces in diverse places with different speaker configurations.