Monitoring (sound engineering)

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Monitoring (English to monitor , from Latin monere, admonish, warn ) means in sound engineering the sound reinforcement of artists or sound engineers . At events with live music, there are usually monitor speakers or in-ear monitoring to provide sound for the musicians on the stage, since the PA system does not cover the stage at all or not sufficiently. The monitoring is used by artists to control their own playing , singing or speaking and offers an orientation to their acoustic environment. In the recording studio , it also allows control over the recorded and edited material; in addition, studio monitors are used, which (in contrast to hi-fi boxes ) are characterized by a particularly neutral reproduction.

Monitoring on stage

Monitor loudspeaker (horn tweeter with 12 "bass-midrange speaker) for stage use

From a certain stage or room size monitoring is essential, as for example by singers because of the usually high volume of public address system ( PA ) and the other instruments (such as drums ) can be heard hardly satisfactory to the sound of your own voice.


In addition to the regular sound system for the audience, a separate sound system is usually set up for the stage area alone ("monitor system"). The stage sound reinforcement gives the musicians a hearing impression that is similar to that of the audience and enables them to better coordinate the interaction.

In order to minimize feedback effects between the monitor speakers and vocal microphones, special wedge shaped boxes are used, so-called wedges ( English for wedge ) which lying on the ground under the microphones obliquely upward beams from the front to the musicians.

This system is operated from its own monitor mixer , which is positioned behind the PA system in order to be able to control the audio impression on the stage, or from the main mixer ( FoH ). When monitoring via loudspeakers, doing without a separate monitor mixer is only an emergency solution that is chosen for reasons of cost, especially for smaller events. The disadvantage is the need for two people to adjust the level: A technician has to communicate the hearing impression on the stage to his colleague at the main console, who then operates the equipment and in turn has to have the change described to him. This lengthy procedure can only be carried out in advance during the sound check . Since the acoustic situation has changed during the performance in front of an audience, the musicians usually still have to transmit their change requests "on the fly", for example by gestures to the FoH mixer. There are no such disruptions in the performance both with the monitor mix (adjustment and control is carried out continuously by one and the same employee), as well as with the in-ear monitoring explained below , which can be controlled from the main console, since the hearing impression via earphones is location-independent.

The sound requirements differ somewhat from those of monitoring in the recording studio, where a linear frequency response is the main requirement. When monitoring live concerts, the loudspeakers must be able to reproduce high volumes without distortion. However, a linear frequency response is also important here in order to avoid feedback . To suppress them, problematic frequencies (e.g. resonances due to room acoustics) are often reduced by means of an equalizer in a narrow-band and steep-edged frequency response. Special devices, so-called feedback destroyers , can also be used for this purpose .

Earphones for in-ear monitoring

In-ear monitoring

Since the use of stage loudspeakers is a difficult condition for sound engineers and musicians, there is an increasing trend towards the use of earphones (in-ear monitoring) , which are not directly visible to the audience. In contrast to the stage loudspeakers, there is no feedback here that would normally arise if, for example, a microphone picks up the amplified vocals of a singer, which are reproduced via the monitor loudspeakers. In addition, the sound impression for the musicians is independent of their location on the stage. In order to allow the artists freedom of movement, the connection between the monitor mixer and headphones is usually via a radio link. There are also wired solutions for musicians with a permanent location on the stage (e.g. drummers or keyboard players).

Advantages of in-ear monitoring are:

  • The listening impression remains constant, regardless of whether you are in the rehearsal room or on a stage.
  • An in-ear set, which consists of a transmitter station and a body-wearing receiver (bodypack), is much easier to transport than a conventional monitor box.
  • An in-ear monitoring system can be used to give stage directions (e.g. for television broadcasts) without the audience noticing.
  • In-ear monitoring allows the band to use a metronome without the audience noticing, as the metronome (the click ) can only be heard on the artist's headphones.
  • Less noise pollution for the performers on stage.

Disadvantages of in-ear monitoring are:

  • The changed spatial impression for the musicians, since the sound impression does not change when moving or rotating. In extreme cases, this can lead to orientation difficulties.
  • In certain areas (singers, speakers, brass players) the sound impression can be falsified due to the bone conduction in the skull . When using hard plastic, it can also be uncomfortable to wear.
  • Only useful for a certain number of people who appear; for many actors more complex and considerably more expensive than monitor boxes on the floor.

Monitoring in the studio

A distinction must be made between two applications in the studio. On the one hand, the artists are supplied with a suitable sound signal during their performance. Mostly through headphones they hear themselves, a metronome, the other musicians or a mix of the existing arrangement (when overdubbing ) , depending on the needs . On the other hand, the use of the monitoring system (the listening devices) through which the sound engineer examines the audio signals or the mix is ​​also referred to as monitoring.

The visual appearance of the artist does not play a role in studio recordings, so no in-ear monitors are necessary, but closed headphones are usually used, except when recording purely electronic instruments. So that

  • With simultaneous recording of all musicians, feedback between monitor speakers and microphones is avoided or
  • With overdub recording (recording of individual musicians one after the other), a new recording of the material already recorded from the monitors via the microphones is avoided, as this can lead to undesirable sonic results (e.g. due to phase shifts).


There are special requirements for monitoring in the recording studio. First of all, this means reproducing the audio signal in question exactly as it is output by microphones , amplifiers or other sound generators. This is not the case with commercially available hi-fi systems and some PA systems, the frequency response is distorted in different ways. The sound image is therefore not sufficiently equivalent to the original signal for studio purposes, resulting in a falsified hearing impression. Therefore, specialized monitor speakers are usually used in the recording studio .

A mastering , for example, absolutely requires a sound system as a reference basis. You need a reference when mixing, due to the fact that music is heard on very different sounding systems (and rooms).


Monitor loudspeakers are special loudspeakers for musicians or sound engineers that are used for listening purposes and are therefore subject to special quality criteria. Above all, this includes the desired linear frequency response for the purpose of a reference-capable sound image. A true-to-signal sound image, which is essential for sound monitoring in the recording studio, requires expensive equipment: the so-called studio monitors. It is also necessary to optimize (or minimize) disruptive room resonances as well as intact and appropriately trained hearing.

For a long time the type monitors NS-10M of Yamaha widely used in recording studios. These loudspeakers "simulated" the limited playback conditions as they were to be expected on the part of the end user, quite meaningfully. Today there are numerous manufacturers, some of which are specialized, such as Klein and Hummel . For monitor boxes in the form of headphones , the same criteria apply except for the room influences, here, for example, the K 270/271/272 from AKG Acoustics and the Beyerdynamic DT 880 Pro were used as references.
The desired quality of the sound radiation in the room desired by a loudspeaker also depends on:

  • the amplifier used,
  • the type, layering and shape of the outer and inner material used (due to the material's own resonance behavior),
  • appropriately used transducers (drivers, chassis), crossovers, insulating materials and other built-in components,
  • the positioning of the listener and the loudspeakers in the room.


  • Rolf Beckmann: Manual of PA technology. Basics, components, practice. 2nd Edition. Elektor-Verlag, Aachen 1990, ISBN 3-921608-66-X .
  • Michael Ebner: manual of PA technology. Elektor-Verlag, Aachen 2002, ISBN 3-89576-114-1 .
  • Roland Enders: The home recording manual. The way to optimal recordings. 3rd, revised edition, revised by Andreas Schulz. Carstensen, Munich 2003, ISBN 3-910098-25-8 .
  • 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
  • Siegfried Wirsum: Practical sound reinforcement technology. Device concepts, installation, optimization. Franzis-Verlag GmbH, Munich 1991, ISBN 3-7723-5862-4 .

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