Stereo recording techniques

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Room-related stereophony tries to reproduce the sound field of the recording room with loudspeakers in the replay room.
In principle this works better the more transmission or recording channels are used and the less influence the replay room has on the sound picture. Initially the limitation of the transmission to only two channels has been made for economic reasons, since additional expense does not bring adequate gain in the reproduction of the sound picture.
As in the case of natural listening, sound localization is realized on the basis of intensity and/or delay-time differences between both channels (see Sound perception 3.1 and 3.2).
Whether intensity or delay-time stereophony or a combination of both is used will be determined solely by the recording technique, not by the listening arrangement. With a suitable loudspeaker arrangement, room-related stereophony produces a sound pattern stationary in the room. The sound picture will be optimally reproduced only inside the stereo listening area (see Sound perception 4).

There are different recording techniques for the room-related stereophony:

Due to the arrangement and the directional characteristics of the microphones used for intensity stereophony, the stereophonic sound impression is mainly determined by intensity differences or level differences between the stereo signals L (left) and R (right).

Three microphone techniques can be used for intensity stereophony:

1. several mono microphones, whose signals at the replay side will appear along the "stereo basis"
2. one or several coincident-microphones switched on XY - technique
3. one or several coincident-microphones switched on MS - technique

Coincident microphones unite two independent microphone systems, one on top of the other.

With AB - stereophony the stereophonic sound impression is determined due to delay time differences between the signals of two mono microphones, set up at a certain distance from each other.

Fig. 5: Stereo-Recording Systems

Stereo Recording Techniques (570 KB) Download this document in Acrobat format for printing and offline viewing.

Stereo recording techniques