Development of a Digital Noise Exposure System for Research on Noise Induced Hearing Loss

Over 30 million Americans suffer from noise induced hearing loss (NIHL). Many research projects demonstrated that different types of noise, even with equal sound energies, could produce different amounts of hearing loss. In this project, a novel digital noise exposure system has been developed for generating various noise signals (e.g., pure-tone, Gaussian, impulsive, and complex noise). The developed system can be used to study NIHL produced by different types of noise in an animal model. The system could produce impulse noise with peak sound pressure level (SPL) up to 160 dB, which effectively mimics the noise generated by a military weapon (e.g., M-16 rifle). In addition, continuous Gaussian noise with peak SPL up to 140 dB can be created, which is well above the 85 dB recommended exposure limit established by the National Institute for Occupational Safety and Health (NIOSH). The preliminary results of in an animal study showed significant permanent threshold shift (PTS) produced by 90 shocks impulse noise with peak SPL = 155 dB generated by the system. In summary, the digital noise exposure system replicates environmental noise allowing researchers to study hearing loss in a controlled situation.