Mixed hearing losses occur when there is a difficulty in the outer or middle ear that prevents sound from entering the inner ear and there is a loss of transmission of the impulses to the brain from the inner ear (usually due to a loss of hair cells). Even when sounds are made loud enough to overcome the conductive portion of this hearing loss, individuals will still have difficulty understanding speech due to the sensorineural portion of the hearing loss. Medical or surgical intervention can improve the conductive portion of the hearing loss and a hearing aid can help improve understanding for the sensorineural portion of the hearing loss. Common causes of mixed hearing losses are any combination of the above causes for conductive and sensorineural hearing losses.