In-ear monitors (IEMs) allows a performer on stage to hear a mix of audio sources coming from the stage whilst blocking out the louder sources allowing for a more personalized mix of vocals and instrumentation. IEMs typically use a wireless monitoring system which sends the audio sources via a transmitter to a receiver pack which the performer wears. The earpieces are the last stage in the signal chain and allow the sound to be delivered directly to the performer’s ear canal.