A case of conductive hearing loss can be caused simply by accidentally pushing ear wax (cerumen) onto the tympanic membrane with a cotton swab or by water entering the ear canal, occluding it, and causing the ear wax to swell. This can be removed by careful suction by an ENT doctor.
Severe damage of the conductive type can also be caused by injury to the tympanic membrane or middle ear, which can be caused by damages linked to diving or an explosion, cases in which the tympanic membrane usually suffers extensive lesions. This is usually evident from the events themselves or a simple examination that will indicate the ruined tympanic membrane. The maximum hearing loss that can be caused by such damage is 40dB.
Finally, head traumas, such as those can be caused in a car accident, can break the auditory ossicle chain. The most common damage location is the connection between the incus and the stapes ossicles (incudostapedial joint). Such a case will result in a complete auditory chain discontinuity and a conductive failure of 60dB is caused.
In all the above cases, a reliable Tonal Audiogram is required in order to determine whether any sensorineural damage has been caused, a fact that would severely alter the chances of full recovery.