Having a 3D sound image when using IEMS is a necessity because:
- Our brain is used to a 3D sound image, exposing it to a one-, or two-dimensional sound image will cause fatiguing and even dizziness.
- The 3D sound image allows distinguishing between different sound sources and even to auto-mix them, which reduces the need for constant re-adjustments in an IEM mix.
Fact: our brain doesn’t have a “mono switch”. The entire three-dimensional hearing is based on differences between both ears in level, arrival time and reflections. If the brain can’t find any differences, it starts searching even harder for them- our “CPU” is running in full-power, without any chance of success and after a while fatigue kicks in. It also creates a listening experience that many musicians describe as strange, isolated, away from the room…. It is much more the absences of a 3D sound image than the missing ambiance.
Imagine a table in a restaurant with 10 people around and everybody is talking to each other. All of a sudden you hear your name from the other end of table- you can focus on this person that mentioned your name by literally “bringing the level up” while reducing level on everybody else to understand a conversation that you didn’t hear before. That only works because the brain has analyzed a distinct position (based on the intra-aural differences) for each person at the table. If you listen to a group of people through a loudspeaker, there’s nothing you can do, because the loudspeaker is only one source.
So when using IEMs while performing music, creating a 3D sound image is needed for an easy listening experience and to be able to distinguish the individual instruments and voices.