The conductive hearing loss is when there is something which is blocking the sound from getting into the inner ear. The blockage may be in the outer ear portion, or in the middle ear. This kind of hearing loss tends to make sounds softer, and make the ear feel plugged up. Conductive hearing loss can be temporary or permanent.
Sensorineural hearing loss is when there is damage to the inner ear. This is most commonly caused by ageing, but can also be due to exposure to loud noise, or a genetic condition. This kind of hearing loss is usually permanent. It can make sounds unclear as well as softer, and often gives the feeling that people are mumbling.
Mixed hearing loss is a combination of both conductive and sensorineural hearing loss.