In ear monitors are devices used by performers to hear a mix of microphones and/or instruments that are on the stage. They are often custom fitted to the individual's ears and provide a high level of noise reduction from stage noise.
Monitoring systemA monitoring system is any system that provides a mix of audio sources to a performer on stage. Traditionally the monitoring system was a loudspeaker placed on stage directed toward the performer that was outputting a mix of audio signals so that they may hear what they and the other performers are doing audibly. The sources can be mixed from one of two locations, the monitor world or Front of House (FOH). Monitors are only mixed from Front of House when the total size of the sound system is small enough that the person operating the sound system from Front of House can handle both the tasks of mixing the monitors and the house sound (more on this process in the article Live sound mixing). If the mix does not come from Front of House then it is done from Monitor World, which is usually set up in either wing of the stage. The engineer at this position combines a number of signals coming from microphones or instrument pickups and sends that mix to the individual mixes for the performers. The more popular monitoring system that is in use today by larger tours and events is the In Ear Monitoring system. This system is usually wireless and contains three major components: the transmitter, the receiver, and the monitors themselves.
Transmitter and receiverThe most common In Ear Monitor system employs the use of a wireless system to send the mix to the monitors. This system contains a transmitter and a receiver pack that is worn by the performer. There is generally a transmitter for each monitor mix and always a receiver for each monitor. The transmitters usually output either one stereo mix or two mono mixes. When the transmitters are set up for two mono mixes, one transmitter can be used for two different mixes. As stated before, there is always a receiver for each monitor being used. Though more than one receiver can receive a single mix, two monitors almost never share a receiver. The output from a receiver is generally too weak to power two monitors at the same time.
The Transmitters and Receivers transfer audio wirelessly via a VHF or UHF radio frequency. Generally speaking, UHF systems sound much better than VHF systems and are therefore more expensive to purchase. UHF systems usually are less impervious to frequency interference which adds to their level of quality.
In ear monitorThe In Ear Monitor is the last stage of the signal path in an In Ear Monitor system. It is made up of a wire and a bud that connects to the Receiver pack worn by the performer. The bud end of the monitor is often custom molded by an Audiologist and therefore is more comfortable to wear and provides a higher level of noise reduction (usually between 25 and 40 dB SPL). If a mold is not made, lower end monitors include a variety of universal foam and rubber tips that will fit into most people's ears (pictured at left). The monitors come in a variety of colors but usually are clear or a color that closely matches the skin color of the performer. The wire of the monitor runs down the back of the performer and plugs into the receiver pack that is clipped onto the belt or clothing of the performer. When seen casually, the monitors look like a pair of hearing aids with wires running out of them.
BenefitsThe benefits of an In Ear system are many. One of the key benefits is the fact that the performers ears can be protected from high Sound pressure Levels that exist on a concert stage. Of course, if they turn up the volume of their monitors too much, this benefit is defeated. The other benefit of the noise reduction offered by the monitors is that the performers only hear what is added to their mix, providing a higher level of clarity. Since they are wearing a bud in each ear, the performers can also hear a stereo mix if the monitor console, transmitter, receiver, and monitor offers this feature of course. When a stereo mix is done correctly, each individual instrument and voice can be heard more clearly since they are panned out to their own individual space in the stereo image.
All the benefits listed are defeated if the monitor engineer does not know what he is doing of course. A good monitor engineer has the ability to augment these benefits and provide a clear and pleasing mix to the performers. When a performer, especially a musician, is hearing themselves clearly and with an artistic amount of effects, they are inspired and encouraged to perform their best, resulting in a much more enjoyable performance for the audience present.
A case of in ear monitor receivers
A rack of in ear monitor transmitters
A typical In Ear Monitor
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