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Though sometimes not the best in absolute sound quality it is the ability for the microphones to be controlled by the delegate as well as the technician that maximises the chances that every word is heard.
For this reason conference microphones are particularly suited to recording meetings and in the provision of the 'original' feed to simultaneous interpreters.
In both these applications it is best to have as few microphones live as possible at any one time. Each 'open' microphone adds more back ground noise to the audio without enhancement.
The operation of a standard sound desk with just 6 conventional microphones on a top table is to leave all 6 microphones partially live so if someone does speak the technician need only increase the level of an already live microphone. This allows at least some audio, albeit low level to begin with, to be heard which is better than nothing. This is the practice because the technician does not know who is going to speak next and the speaker is unable to make their microphone live independent of the technician. There are two main reasons why this is not acceptable in a recording or interpretation environment.
Firstly the delay in a delegate speaking and in the microphone becoming live, as the technician recognises which microphone is in use and increases its level, introduces a pause into which whole sentences can disappear and critical meaning can be lost. Conference microphones can be operated by the speaker directly so eliminating this delay in making the microphone live or louder. This creates a freer flow of dialogue to take place without a word being lost. This is critical in the recording of important meetings and in the original language feed for simultaneous interpreters.
Secondly by having so many partially live microphones live you are introducing unwanted and distracting background noise into the audio. This is often not recognised by the delegates or by the technician who generally listen to the audio via the room acoustic in which these noises are already present. However other users like interpreters listen to the proceedings via headphones so they hear very close to the audio and can clearly hear the rustle of paper or the pouring of water. This unwanted audio is very distracting and masks the audio.
With conference microphones placed on lecterns you have the capability to control and eliminate these sounds without losing the critical audio needed by only having one or two microphones live at any one time. And this advantage is possible in a system for 50 - 100 participants yet using conventional microphones and a mixer is difficult on a top table with just 6 speakers in a panel discussion.
The advantages in using a conference microphone or discussion system are very clear (especially the audio).
