
Bell witnessed the impacts of hearing loss firsthand. His mother lost her hearing as a child and his wife was deaf. Additionally, his grandfather, father, and brother all worked in areas associated with speech and hearing. This exposure and subsequent interest led him to develop the first audiometer in 1879. Around that same time German physician, Hermann Ludwig Ferdinand von Helmholtz, invented an electrically driven tuning fork to measure hearing sensitivity.
Read the whole story in Canadian Audiologist.