The ER-6 Isolator Earphone reduce environmental sound levels 15~20 dB, allowing you to hear the full range of todays digital recordings without having to play them at unnaturally high and unsafe levels. Since you do not have to boost the volume to overcome external noise, ear overload distortion is minimized. True high fidelity sound reproduction requires the reproduced sound to be as close as possible to the sound of a live performance. ER-6 Isolator Earphone is designed to match the acoustic response of the open ear.