The relations of eye colour and smoking to noise-induced permanent threshold shift

The hearing of 118 otologically normal soldiers 40 years of age or less with at least 8 years service was tested. Their eye colours were also recorded. Each soldier was questioned concerning his medical history, history of noise exposure and smoking habits. Left ear average hearing levels at 3 kHz were poorer in soldiers with eye colours indicating no melanin pigmentation of the iris than those with iris pigmentation (p < 0.05). Effects of smoking were statistically significant at one frequency but difficult to interpret in terms of current theories.