Intensity stereophony

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Intensity stereophony , also known as level difference stereophony , is a loudspeaker stereophony process to achieve a stereo impression for the ear . The directional localization of a sound source heard in the sound field of the two stereo speakers is created by level differences .


Another name for intensity stereophony is level difference stereophony, because the right-left differences in sound intensities correspond to differences in sound pressure levels that affect human ears. Other methods for generating a stereo field work as equivalence stereophony in addition to the level differences with transit time differences or as transit time stereophony predominantly with transit time differences.

Intensity stereophonic signals can be obtained through

In the past, intensity stereophony was the predominant method, especially in broadcasting, because of its monocompatibility: when the channels are superimposed, there are no comb filter effects due to the phase equality .

Mixing of mono signals

The most important processing means for mono signals is the mixer, which enables the placement of any audio event direction for phantom sound sources on the stereo loudspeaker base. The intensity stereophony is said to have the best localization sharpness . This simple merging of mono sound sources into a stereo panorama is also known as stick stereophony . The intensity stereophony also includes polymicrophoneing , which works with completely separate mono microphone signals and whose phantom sound sources are set in the desired direction of the audio event on the loudspeaker base via panorama controls . This is the usual recording technique in light music, especially for instruments with electronic pickups, which are necessarily in mono.

Microphone systems

A main microphone system for generating stereophonic audio signals consists of two microphones.

With all time-less stereo microphone systems, the distance between the membranes would ideally be zero. Since this is not possible, the microphones are arranged vertically one above the other as close as possible. It also follows from this that clean intensity stereophony is only possible if the sound sources are more or less in the horizontal plane of the microphone system.

The intensity differences of the stereo channels are obtained by using the microphone directional characteristic . The two microphones used for this purpose mostly use directional pressure gradient microphones with directional characteristics between cardioid and figure eight, but pressure microphones with omnidirectional characteristics are also used.

XY stereo system

XY stereo microphone with 90 ° axis angle

The XY stereo system consists of two vertically stacked microphone capsules with cardioid polar pattern, which are rotated about 90-180 ° apart. In practice, angles of at least 120 ° are common so that the system can be positioned in front of the sound body (see especially the XY stereo system ).

Due to the negligible horizontal microphone spacing and the directional characteristics, when the XY microphones are angled, depending on the direction of the sound angle of incidence, frequency- neutral level differences arise between the signals from the two microphones. The recording range of the stereo microphone system is determined by the axis angle between the microphones . These coincidence microphones (stereo microphones) thus act like acoustic panorama controls. It also leads to sound recording with the greatest localization sharpness ; see web links.

MS stereo system

Mathematically equated with the XY recording technique is the MS recording technique (MS = center-side), in which the S-signal (directional signal) is generated by a side-facing microphone with figure eight characteristics. A microphone (center signal) with any directional characteristic can be directed towards the front of the sound source. The smallest possible distance should be between the microphone capsules - which ideally is zero. A digital or analog circuit converts the middle-side into left-right signals.

Blumlein stereo system

Blumlein -Stereo.png

The Blumlein stereo system provides two eight-eight microphones crossed at 90 ° .

Ideally, the microphone capsules are arranged as close as possible to one another. The Blumlein method is suitable for all real pressure gradient microphones with the directional characteristic of a figure eight. Compared to the other methods of intensity stereophony, the Blumlein method is characterized by particularly good spatial reproduction and a broad stereo base.

Pure intensity stereophony

In pure intensity stereophony, there are no runtime differences. A level difference between ∆ L = 16 and 20 dB then leads to a hearing event direction of 100%, i.e. fully from the direction of a loudspeaker. Mean calculated value ∆ L = 18 dB. The interchannel level differences ∆ L generated between the loudspeaker signals should not be confused with the level differences ILD ( Interaural Level Difference ), which result as ear signals at the ears of the listener .

A sound recording with a main microphone system is often supplemented by support microphones .

A phase indicator ( correlation meter ) or a goniometer can be used to check the stereo signals L and R, which should arrive with the same phase in intensity stereophony .


  • Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.): Handbuch der Tonstudiotechnik , 8th, revised and expanded edition, 2 volumes, publisher: Walter de Gruyter, Berlin / Boston, 2014, ISBN 978-3-11- 028978-7 or e- ISBN 978-3-11-031650-6 .
  • Hubert Henle: The recording studio manual. 5th edition, GC Carstensen Verlag, Munich, 2001, ISBN 3-910098-19-3
  • Thomas Görne: Sound engineering. 1st edition, Carl Hanser Verlag, Leipzig, 2006, ISBN 3-446-40198-9

See also

Individual evidence

  1. ↑ Direction of hearing events depending on the interchannel level difference, EBS, (PDF; 117 kB)

Web links