One approach would be to have a monitor operator updating the pan pots of the ambient mics on the fly, following the artist in real time by watching their movements and updating the directional cues. Yeah, right! Not a very reliable or repeatable solution.
Or, maybe a GPS-enabled pan-tracker gizmo in the future.
So in most worship environments, we live with stationary ambience. It’s manageable, and its still far better than no ambience.
Also, because the “aesthetics police” are often present, that X-Y mic pair often gets removed from the center downstage location. They typically wind up one on each end of the stage, crossed toward the back of the audience. That’s OK; it’s a compromise that can still provide a usable spacious image.
But what if we were to mount a subminiature ambient mics (which are essentially serving as artificial ears in this application) on either side of the head, or on the outside of the earphones themselves? Then, no matter where the user moves, the directional cues always work because the mics move with the user. Nifty. There are a few technologies emerging on the market that integrate some type of of binaural miking with in-ear monitors.
Another market trend is the inclusion of an ambient mic on a personal, on-stage monitor mixer or even clipped onto a user’s lapel. These are great for communication (especially during rehearsals) and a little ambient sound, but do not provide accurate directional cues or a stereo sound field.
Potential Timing Issues With Ambient Mics
Sometimes, sound engineers will place ambient mics further back into the audience area, attempting to minimize sound leakage from the stage and PA into these mics. While that may decrease the leakage, it creates latency: there is still some leakage, but it now takes a little while for that sound to travel from the stage and PA to the mics. The further away the mics are from the PA, the longer it takes.
When such located mics are combined into an in-ear monitor mix, the timing offset can be problematic for musicians attempting to play tightly together, as they hear slightly out-of-time musical leakage and sometimes degraded fidelity due to comb filtering. These mic placements may be more useful for recording or broadcasting applications where they can be carefully used to helped convey venue size to the audience.
But in such applications, no musician is relying on those mixes for critical performance monitoring. So, keeping any ambient mics that may be mixed into IEMs close to the PA is a wise move. After all, we’re talking about LIVE sound, not LATE sound.