1. NIOSH, Criteria for a recommended standard-occupational noise exposure; 1998.
2. Casali JG. Advancements in hearing protection: technology, applications and challenges for performance testing and product labeling, InterNOISE2005, The 2005 International Congress and Exposition on Noise Control Engineering; 2005.
3. Hearing protectors;Gerges,2007
4. Cheng M, Hodgson M, Baskerville O. Evaluation and improvement of the acoustical performance of vented earplugs, Canadian Acoustics, vol. 24(3). p. 73.
5. Review and tutorial – methods of measuring the attenuation of hearing protection devices;Berger;J Acoust Soc Am,1986