Workers with Hearing Impairment / Deaf

Yes, workers with a hearing impairment (including those who wear hearing aids) or are deaf must be included in an occupational hearing conservation program if they are exposed to hazardous noise.

Answer Extra: 

Employers are still required to provide annual audiometry and training, and those workers exposed to hazardous noise must wear hearing protection devices (HPD). These workers still need to preserve whatever hearing they still have.
Though a worker may be hearing impaired or deaf and wear a hearing aid, they are still required to use hearing protection when exposed to hazardous noise levels. While a conventional single-use foam or multiple-use earplug may not be ideal for these workers, there are several options available from manufacturers - such as uniform attenuating HPDs or sound amplification protectors.