In this issue, we’ll look at some tips and tricks I’ve picked up over the years for better working with in-ear monitors (IEMs), plus some interesting problems I have helped people overcome.
The major starting point for any IEM, or even MP3 player earphone, is fit. Without good fit, you are fighting a losing battle for quality sound right from the start. At the recent NAMM Show, I had a couple of musicians ask me why they could not get any more gain out of their lead vocalist’s IEM system. The minute they added the keyboards to her vocal mix, it compressed the vocal and caused the limit lights to activate on the transmitter and receiver belt pack.
As I continued to ask questions intending to dig down to the true root of the problem, it eventually was determined her IEMs fit so poorly that they fell out constantly. This indicated the “limiter” issue was really a case of her having a terrible seal at her ears. The poor seal meant she had a great deal of loud external stage noise to overcome, a good portion of the sound her IEM was managing to create escaping her ear canal, and very little low frequency content since a proper tight seal is necessary for good bass reproduction.
This aspect – the proper acoustic seal at the ear – is doubly important as there is a psycho-acoustic effect where our brains perceive an increase in bass/low frequencies as an increase in overall volume. In practical terms, this means getting a better seal for stronger bass or turning up the low end creates the effect of turning up the entire mix, but without the damaging effects to our hearing that would occur if we simply turned up the overall mix a seemingly equal amount. This allows for longer exposure times before the harmful effects of volume set in. This also means musicians should not wear their IEMs loosely with an intentionally broken seal so they can hear the outside world better. Instead, they should use audience or ambience microphones as a regular part of their monitor mix. These microphones can then be turned up by the monitor engineer between songs, so performers can keep wearing their properly sealed IEMs.
Next issue, we’ll continue with more on psycho-acoustics and other tricks of the trade.
Keith Gordon is a veteran audio engineer who began using IEMs in the mid-90s. Recently, he helped develop a DSP-based hardware/software IEM system in conjunction with Westone Laboratories. He can be reached at firstname.lastname@example.org.