Hearing loss is categorized according to site of lesion (site of the problem). If the pathology lies in the outer or middle ear, the hearing loss is categorized as a conductive hearing loss. If the pathology lies in the inner ear, central auditory nervous system (CANS) or auditory cortex, the hearing loss is a sensorineural hearing loss (sensory part is the inner ear and neural part is the CANS and cortex). Examples of pathologies include:

• Outer ear – e.g. Atresia (missing ear lobe) or microsia (small underdeveloped ear lobe)
• Middle ear – e.g. Middle ear infection, Eustachian tube blockage, Tympanic membrane (eardrum) perforation, otosclerosis (bony growth of the stapes middle ear bone)
• Inner ear – e.g. Noise induced hearing loss, presbycusis (aging), Meniere’s diseases, vestibular neuronitis (affects balance).

CANS and auditory cortex e.g. Multiple sclerosis, stroke, head injury