There are generally two types of professionals that deal with hearing loss in a hearing clinic setting. The first is an audiologist, the second, a hearing instrument practitioner.
Audiologists have a minimum of six years of university training and are comparable for your hearing to what optometrists are for your vision. They are not medical doctors, but do have specialized training in the prevention, diagnosis, and rehabilitation of hearing loss, tinnitus, and related communication and counselling issues. They primarily work in hospitals, schools, health units, and hearing clinics.
Hearing instrument practitioners have two years of post-secondary education and are comparable in the hearing world to what opticians are in the vision world. They also test hearing and fit hearing aids, but do not have the extensive training that audiologists do.