In-ear monitors (IEMs) are used by musicians during live performances to hear themselves and their bandmates clearly, while protecting their ears from high stage volume. Unlike regular headphones, IEMs offer superior noise isolation and are custom-fitted for comfort. Major manufacturers include Shure (SE Series), Westone (UM Pro Series), Audio-Technica (M Series), and Sennheiser (EW IEM systems). IEMs are vital for touring musicians, offering clear sound on stage and improving performance accuracy by isolating stage noise.