One Or Two Ears?

Yep, I went there… it’s important.

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.

It’s most common with vocalists, in my own experience. They are certainly most comfortable with their raw and open ear(s), as they’ve been using them reliably their entire lives. But if the monitor mix is really needed and is suitably delivered to the earphones, they should wear them both. One good way to achieve this is to work toward a proper and comfortable IEM mix so that the artist is not tempted to remove either earphone. That may include ambient miking and mixing, and we’ll get that to shortly…

Using one earphone on the live stage often brings an accompanying increase in monitoring volume, finally controlled by the user at his/her bodypack receiver. This author has witnessed this in enough scenarios to note a trend: it seems that a single earphone (all else equal) tends to be run at least 10 dB louder than two earphones!

One reason is simple: the open ear is not sealed and hears the array of surrounding stage sounds, which are often fairly loud, and the single earphone in the other ear naturally must be turned up considerably to compete clearly. Also, when one earphone is removed, “binaural summation” is defeated. This is a psychoacoustic phenomenon that very positively affects listener perception of loudness—but it only works with two ears. Yikes!

So on top of the already increased monitoring volume, the loss of binaural summation causes even higher listening levels to be needed. It’s easy to believe, then, that a single earphone may be run well beyond twice as loud as two earphones. In the interest of hearing health and safety, anything we can do to minimize the sound pressure exposure for all users (IEMs, wedges, or any other application) is the right thing to do.

Avoiding the single ear method for extended use is highly recommended. The better move is to work toward a proper two-ear mix. It is worth the effort.

Ambience/Audience Response

Once the balance of sources is mixed well in an IEM mix, the hard part is done. And for some users, we’re finished.

But others feel the need to overcome the isolation, and we need to find a way around that. After all, performers on stage want to feel like they’re still in the venue with the worshippers—not in an a tight iso-booth at the local recording studio. This means hearing the audience sounds and room ambience. Some of this “space” happens naturally through leakage, but sometimes we must deliberately fix this. Consider this:

A worship tech sets up a new wireless IEM 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 pans the mics hard left and right (for the worship leader’s perspective) and blends them into the IEM.

This can work very well when blended just right. When the WL faces forward, it’s simple…  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 the WL’s left. So, his eyes and ears agree, and the brain likes that.

…That is, as long as he remains facing forward, and center stage. But suppose he moves and turns to face a stage left guitar player during a musical moment, with his right ear now facing down stage. 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 on his right. His eyes and ears disagree. The brain hates this. With stereo IEMs, 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.