This article is provided by Sennheiser.

Have you ever seen an artist remove one earphone on stage? Why is that?

One common reason is that they “can’t hear” or are uncomfortable with their mix when wearing both earphones.

They are certainly comfortable with their raw/open ear(s), as they’ve been using them reliably for a long time!

But if the monitor mix is really needed and is suitably delivered to the earphones, they should wear them.

One good way to achieve this is to work toward a proper and comfortable wireless personal monitor mix so that the artist is not tempted to remove either earphone.

Using one earphone on the live worship stage often brings an accompanying increase in monitoring volume, controlled by the user at his/her bodypack receiver.

This author has witnessed this in multiple live worship scenarios, and it seems that a single earphone—all else equal—tends to be run roughly 8 to 10 dB louder than two earphones. Or more!

One reason should be readily apparent—the suddenly open ear is no longer isolated and hears the array of surrounding stage sounds.The single earphone in the other ear may then have to be turned up to compete clearly.

Also, when one earphone is removed, “binaural summation” is defeated. Humans naturally perceive an increase of up to +6 dB in level when both ears are functioning.

In other words, the perceived loudness is greater than the actual sound pressure level presented at the two ears. Who says there’s no free lunch in audio and acoustics? This is one of many amazing things about the way humans hear, but with only one earphone, it doesn’t work.

So on top of the already increased monitoring volume, the loss of the binaural summation effect causes even higher listening levels to be needed! It’s easy to believe, then, that a single earphone may tend to be run twice as loud as two earphones, or even worse.

In the interest of hearing health and safety, anything we can do to minimize the sound pressure exposure for all users (wireless personal monitors, wedges, or any other application) is the right thing to do. Avoiding the single ear method for extended use is recommended.

Previously we’ve discussed some wireless personal monitor mixing techniques. Once the balance of sources is mixed well in the wireless personal monitors, we’ve come a long way.

And for some users, we’re done. But others feel the need to overcome the isolation, and we need to find a way around that. Consider this scenario:

Figure 1. (click to enlarge)

A worship tech sets up a new wireless personal system for his worship leader and he knows that isolation is part of the game. So, he sets up a stereo pair of cardioid condenser mics in an X-Y configuration (Figure 1), front and center, facing the audience.

This simple stereo technique provides a good image of the audience sounds and some room ambience. He hard pans the mics hard left and right (for the worship leader’s perspective) and blends them into the wireless personal monitor mix.

When the worship leader faces forward, this can work extremely well. If, say, a sound comes from an audience member hollering a response or applauding on the worship leader’s left (house right) it will be heard and seen on his left. So, his eyes and ears agree. All is well…

...That is, as long as he remains facing forward, and center stage. Suppose he moves over to his left a bit (house right), and turns to face a guitar player during a musical moment, with his right ear now facing stage front. What has happened?

That same audience sound is still heard just as easily before, but now there is a localization error. What is HEARD on the worship leader’s left side is SEEN somewhat on his right.

With stereo wireless personal monitors, this “stationary ambience” issue may be a problem for stage performers.

His head orientation moved, but his artificial ears (the ambience mics) did not.

Our eyes and ears like to perceive sources from their correct/coincidental directions, and when they don’t agree, it’s a problem!

In some cases, it’s just annoying. In other cases, it can be completely disorienting.

One approach would be to have a monitor mixer/operator updating the pan pots of the ambient mics on the fly, following the artist in real time by watching and updating the directional cues.

Yeah, right! Not a very reliable or repeatable solution.

So in most worship environments, we live with stationary ambience. It’s manageable.

Also, because the “aesthetics police” are always present, that X-Y mic pair often gets removed from the front/center location. They typically wind up one on each end of the stage, crossed toward the back of the venue. That’s OK; it’s a compromise that can still provide a usable stereo image.

But what if we were to mount the 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.

There are a few technologies emerging on the market that allow this sort of binaural miking for wireless personal 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 will not provide accurate directional cues or a stereo sound field. Nonetheless, it’s a useful thing.

To avoid potential timing issues with ambient mics, find the “time zero” location of your PA system. This is the invisible front line where the sound leaves your main loudspeakers. It is usually along the front edge of the stage or so.

Keeping the audience/ambient microphone(s) lined up with this line, or close, will keep them in time with the PA system. Sometimes, techs 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 does decrease the leakage, it creates a timing problem: 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 a wireless personal monitor mix, the timing offset can be quite problematic for musicians attempting to play tightly together, as they hear out-of-time musical leakage and sometimes nasty sounding comb filtering.

Such microphone placements may be more useful (and less destructive) for recording or broadcasting applications where they can be carefully used to help the venue sound larger. But in such applications, no one is relying on those mixes for critical performance monitoring!

Kent Margraves works with Sennheiser USA.