A few notes in advance …

This learning environment will help you to produce impressive stereophonic sound tracks, even in acoustically difficult rooms and surroundings. We recommend to use headphones, because this will be the best way for you to hear the sound differences.

We want you to experience the different sound tracks in one single 360° video, therefore, a bunch of data has to be downloaded in advance. We will use the short download time to introduce you to some crucial basics of miking, which will enable you to make good sounding stereophonic recordings in the future.

Please click one of the two buttons below and the download of all data will start.

Preliminary remarks

In this 360° video you will experience various options to record music in impressive spatial sound, even when the acoustic conditions are poor. However, this tutorial does not focus on the different technical designs of individual microphone types, but rather on their directional characteristics, as well as their appropriate use and adequate positioning in the room in relation to the sound source, in order to obtain the best possible stereophonic sound recording even in small, acoustically heavily damped and deadened rooms.

Sonic waves are emitted by a sound source and they are reflected by the room boundaries. We are capturing these sonic waves and their reflections with our two auricles. Our brain analyzes stereophonic sound waves principally on the base of three acoustic parameters:

• the interaural time differences between the left and right ear
• the differences of the audio levels between left and right
• the differences in frequency perception between left and right

The parameters of aural data are processed almost simultaneously in our brain and an "acoustic image" of the room boundaries surrounding us is immediately created. Thus we can experience the sound space and are able to navigate within it while perceiving further sonic waves of music, sound effects and speech.

In this learning environment you can experience "online" the advantages and disadvantages of four different microphone arrays while listening to the stereophonic sound of a concert grand.

AB stereophony

Here, the stereophonic impression is mainly created by delay differences between the left and right sound channel. In practice, a distance of approx. 20 cm ("small AB") to 2m ("large AB") between the two microphones A and B has proven effective. In smaller recording rooms, which are often heavily damped, very few acoustic reflections occur, so that the AB recording does not sound particularly good and spatial, because the room itself does not resonate much. Usually, both AB microphone capsules have an omni-directional characteristic. More rarely a cardioid characteristic is used.

XY stereophony

With the XY technique, the recording of sound signals in a small, acoustically damped room is sonically even less satisfactory. Both microphone capsules are positioned at the same place in the room, if possible. Thus, the stereophonic impression is essentially created by the level differences between the left (X) and right (Y) channel. Since, as in AB stereophony, the room is small and produces very few acoustic reflections, the XY array sounds very "pot-like" and also almost monophonic, because differences in frequency and level between the left (X) and right (Y) channel consequently hardly exist in this room. Both X and Y microphone capsules must have cardioid characteristics.

MS stereophony

Mid/Side (MS) stereophony corresponds to XY stereophony regarding the geometric positioning of the mikes in the room, i.e. both microphone capsules should be placed in the same spot. The special feature of the MS stereophony lies in the directional characteristics used: "M" is omnidirectional or cardioid, while "S" ought to be always bidirectional. The latter signal is used electrically twice, once in phase (+S) and once in antiphase (-S). This means, the bidirectional microphone is used as two separate signals. Therefore, three signals are obtained: M, +S and -(-S). Consequently, the emerging stereophonic sound can be "remote-controlled" by adjusting the fader positions of the three audio channels in the mixing console. The double minus sign (- -) refers to the fact, that the -S audio signal must be phase inverted, e.g. in the mixing console.

Close miking the instrument ("grand piano mics")

In this case, three microphones are used: one for the bass strings, one for the middle register, one for the treble strings. All three microphones are positioned directly over the piano strings. Thus, the recording room is acoustically excluded. That implies that any possible room reflection is not registered by the three microphones. Additionally, the use of cardioid microphones is recommended. In principle, this type of miking represents AB(C) stereophony.

Close miking the concert grand, completed with electronic reverb

Close miking acoustically suppresses the natural room sound because the microphones are placed inside or very close to the instrument. Hence, reverb is often electronically added in postproduction. Since no original room sound was deliberately recorded beforehand, an artificial concert hall acoustics can be generated electronically afterwards. This sometimes results in a non-realistic (artificial) sound, which on the one hand pretends a great acoustic proximity of the listener (-> strong brilliance, many trebles), but on the other hand electronically simulates a large concert hall (-> huge room with many acoustic reflections and less trebles). Nevertheless, we have become accustomed to this somewhat contradictory spatial sound as "realistic": This is especially true for film music productions with orchestras and also pop music productions.

How to use the learning environment correctly?

To help you get started, here are some tips for use:

You will experience the university’s own recording room with four different microphone arrays in a 360° video. To hear the differences of the stereo audio tracks, you can choose between the different miking setups. This works in two ways: When the video starts to play, you can control what you hear using your "viewing direction". Just look at the corresponding icon in the video. By clicking and dragging with the mouse, you can navigate within the 360° space. Another method is to turn off the motion control. Now you can easily adjust what you hear with the buttons in the click-bar at the bottom right.