When deafness occurs in the left ear, there are two main clinical considerations: the first is congenital and the second is acquired. Congenital deafness is usually related to genetic factors, or there may be a problem with a particular anatomical structure in the patient’s hearing conduction process during the growth and development process. Acquired deafness is usually related to anxiety, poor rest, staying up late, or after a loud impact or a shock. In terms of treatment, if the patient is congenitally deaf, further detailed examination should be conducted and cochlear implant surgery can be considered if necessary. Acquired deafness must be actively treated with medications that improve circulation and nerve nutrition, and normally the deafness should improve.