Hearing protectors are very important in providing proper protection for workers’ hearing ability in noisy working environments. The government has established laws to enforce the wearing of hearing protectors in noisy working environments, however, the willingness of wearing hearing protectors depends heavily on whether it is comfortable wearing the hearing protector. The purpose of this project is to improve the comfort of hearing protectors. The indices of the comfort of hearing protectors have be measured by collecting ergonomics information and interviewing users and manufacturers. We have also designed procedures and experiments to measure these indices. Then we modify mechanism design of earmuffs and try to avoid over-protection in moderate noise.