PJ, K., V. CS, and Ragini. “Real Ear Attenuation Measurements of Ear Protectors Using Ear Phones: I at Threshold”. Journal of All India Institute of Speech and Hearing, Vol. 13, no. 1, 1, pp. 46-49, http://203.129.241.91/jaiish/index.php/aiish/article/view/662.