earpiece

In-ear monitors (IEMs) 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 in order to receive vocal instructions, info, and breaking news announcement from a producer that only the presenter hears. They are often custom fitted for 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.A monitoring system is any system that provides a mix of audio sources to a performer on stage. Traditionally, monitors were loudspeakers placed on stage directed toward the performer (often called floor monitor speakers or wedges). Depending on the sophistication of the audio system, floor wedge speakers 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 and/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 additional definition of the audio by panning different elements (vocals, drums, etc.) to each ear. Recent advances in this technology also allow the user to incorporate an ambient feature, allowing them to adjust the amount of ambient noise filtered by the IEM.
One additional consideration for mixing IEMs is that while getting rid of 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 out to the audience, to provide a way to get some of the crowd noise and audience comments back into the performers' IEM mixes. Larger live shows could have several microphones for this purpose spread across the front of the stage, which could also be sent to a multitrack recording device used in an outside broadcast production truck, or other destinations.

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