Live performers need some kind of stage monitors that will help them perform accurately and be confident enough to deliver performance magic. The mix of sounds in the monitors, the envelope, ambiance and volume of the sound heard in monitors can make or break a performance... especially a vocal performance.
In my career, I have most often used stage wedge monitors, but recently got a set of in-ear monitors to use myself and to be able to advise my students. I finally made the plunge because these particular in-ears have the capability of adding ambient sound so I'm not feeling cut off from the stage/crowd sounds. My Sensaphonics product is called 3-D Active Ambient in-ear monitors.
I had yet to use them (I'm such a creature of the on-stage wedge), waiting on a question I wanted answered. We've all seen artists on stage, even on the major music award shows, with one in-ear monitor dangling on their neck. I received conflicting advice about the safety of this practice, from other singers and from different doctors. However... the jury is now in:
I met doctor of Audiology Michael Santucci at his Sensaphonics booth at NAMM recently. I asked him point blank about this and he said in no uncertain terms that it creates a serious risk to hearing to use just one in-ear. He explained why, but rather than try and call that up for you verbatim, here is Santucci and Mike Dias of IEM manufacturer Ultimate Ears, explaining it in Mix Magazine:
One danger from too much isolation comes when musicians decide to “fix” the problem by wearing an earpiece in only one ear. “When players take one out, their brain loses its ability to do binaural summation, where two ears together add up to a 6dB increase in your perception of loudness,” Santucci explains. “If you're hearing 90 dB in both ears, your brain thinks it's hearing 96 dB. If you take one ear away, then that one ear has to go from 90 to 96 to sound like 96. And now the other ear is open and getting bashed by the band, the P.A. and the crowd. So this loud sound coming into the open ear causes you to turn the other ear up even more. In terms of ear safety, using one earpiece is a dangerous practice — it could actually be worse than using none at all.”
“There's a common misconception that an artist can use just one earpiece and still use stage monitors, but this results in the worst of both worlds,” says Dias, who offers a simple experiment to demonstrate this. “Have someone stand onstage with a beltpack using one ear and turn it up to a comfortable performing level. Now shut the beltpack off and run the stage monitor to a comfortable level. When you turn the monitors and the single earpiece on, the artist inevitably thinks the in-ear sounds weak and cranks it up to compensate. But when you turn the wedges off, the artist will notice that the earpiece is too loud. In the case of one-ear listening, you don't get the benefit of hearing protection and you don't get the accuracy benefit of the in-ears.”(Read the full article here)
I don't know about you, but I value my ears too much not to heed this advice from this authority. If you find yourself in the habit of dropping one of your in-ears on stage, it might be worth an upgrade to ambient sound in-ears.