In-ear monitor
In-ear monitors, or simply IEMs or in-ears, are devices used by musicians, audio engineers and audiophiles to listen to music or to hear a personal mix of vocals and stage instrumentation for live performance or recording studio mixing. They are also used by television presenters to receive vocal instructions, information and breaking news announcements from a producer that only the presenter hears. They are often custom-fitted to an individual's ears to provide comfort and a high level of noise reduction from ambient surroundings. Their origins as a tool in live music performance can be traced back to the mid-1980s.[1]
A stage monitor system is any system that provides a mix of audio sources to a performer on stage. Traditionally, loudspeakers were placed on the stage directed toward the performers. These loudspeakers can have disadvantages. First, floor wedges greatly increase the onstage volume, in some cases to potential hearing damage levels. Second, while floor wedges can be placed in front of a particular singer, guitarist, bassist, or drummer, the other musicians can often hear the other musicians' wedge mixes. In a sophisticated monitoring system, every band member can have their own monitor mix, which is their particular preference of vocals or instruments.
Since performers wear an IEM in each ear, they can also hear a stereo mix if a particular monitor system allows it. This can allow the additional definition of the audio by panning different elements (vocals, drums, etc.) to each ear. More recent advances allow the user to adjust the amount of ambient noise filtered by the IEM.
One additional consideration for mixing IEMs is that while eliminating floor wedges can improve the overall clarity of the mix for the performers and decrease the overall volume onstage, one important piece that is often lost is crowd noise and crowd comments, such as the audience calling for an encore. It is not uncommon for a microphone to be placed near each side of the stage, facing the audience, to provide a method to capture some of the crowd noise and audience comments back into the performers' IEM mixes. Larger live shows can have several microphones for this purpose spread across the front of the stage, which can also be sent to a multitrack recording device used in an outside broadcast production truck, or other destinations.
Wire[edit]
IEMs typically feature a wire-over-ear or wire (straight) down design.
Wire down is easier to put in with one hand, making it more popular for casual use, where it maybe inserted and removed multiple times per day. It can also be more comfortable, as wearing wire-over-ear with glasses may cause extra pressure and chafing behind the ears.
Wire-over-ear is preferred for professional use, providing a more discreet (run wire behind back, in shirt), secure fit (wire hooks onto ears) with reduced microphonics.
Some wires may come with MMCX connectors to allow replacement once worn out, add-ons like in-line microphone or bluetooth connectivity or upgrading to cables of higher quality or different appearance.
Safety[edit]
Many performers choose to use IEMs as a way to reduce their overall exposure to loud sound and prevent hearing loss. However, education on the use of IEMs is a crucial factor for limiting exposure as performers have a tendency to set their IEMs to similar intensity levels that were previously used in their floor monitors. Musicians need to train themselves to listen at lower levels to take full advantage of the sound level reduction capability of IEMs.[4]
Some musicians with two IEMs may choose to take out one of them during a performance to hear more ambient sound. The increased risk of hearing damage in this scenario are twofold. Removing one IEM negates the improvement in signal-to-noise ratio from isolation and the binaural summation effect which causes an increase in perceived loudness from using two sound sources. Therefore, the performer will likely turn up the IEM in the other ear to improve the signal-to-noise ratio. Also, the ear without an IEM is potentially exposed to loud ambient sound.[4][5]
Many IEMS use peak limiters or compressors to limit potential damage from sudden loud sounds. However, this does not prevent the performer from turning up the IEM to unsafe levels.[5]