CAT and noise induced hearing loss: Current studies have shown that the polymorphisms of potassium ion channel genes (like KCNQ4 and KCNE1) [14, 15], catalase (CAT), protocadherin 15 (PCDH15), myosin 14 (MYH14) [16] and heart shock protein (HSP70) [17] detected in different populations are significantly related to the development of NIHL.