Diagnosis requires a detailed history, local examination of the ear, nose, throat and neck, and detailed hearing tests. In children a more detailed examination may be required if the hearing<unk>  is congenital. Otoscopy Examination of the external ear canal and ear drum is important and may help identify problems located in the outer ear up to the tympanic membrane. Differential testing For basic screening, a<unk>  can be identified using the Rinne test with a 256 Hz tuning fork. The Rinne test, in which a patient is asked to say whether a vibrating tuning fork is heard more loudly adjacent to the ear canal (air conduction) or touching the bone behind the ear (bone conduction), is negative indicating that bone conduction is more effective that air conduction. A normal, or positive, result, is when air conduction is more effective than bone conduction. With a one-sided<unk>  component the combined use of both the Weber and Rinne tests is useful. If the Weber test is used, in which a vibrating tuning fork is touched to the midline of the forehead, the person will hear the sound more loudly in the affected ear because background noise does not mask the hearing on this side. The following table compares sensorineural hearing<unk>  to<unk> : Criterion Sensorineural hearing<unk> <unk>  Anatomical site Inner ear, cranial nerve VIII, or central processing centers Middle ear (ossicular chain), tympanic membrane, or external ear Weber test Sound localizes to normal ear Sound localizes to affected ear (ear with<unk> <unk>  Rinne test Positive Rinne; air conduction - bone conduction (both air and bone conduction are decreased equally, but the difference between them is unchanged). Negative Rinne; bone conduction - air conduction (bone/air gap) Tympanometry Tympanometry, or acoustic immitance testing, is a simple objective test of the ability of the middle ear to transmit sound waves from the outer ear to the middle ear and to the inner ear. This test is usually abnormal with<unk> . A type B tympanogram reveals a flat response, due to fluid in the middle ear (otitis media), or an eardrum perforation. A type C tympanogram indicates negative middle ear pressure, which is commonly seen in eustachian tube dysfunction. A type As tympanogram indicates a shallow compliance of the middle ear, which is commonly seen in otosclerosis. Audiometry Pure tone audiometry, a standardized hearing test over a set of frequencies from 250 Hz to 8000 Hz, may be conducted by a medical doctor, audiologist or audiometrist, with the result plotted separately for each ear on an audiogram. The shape of the plot reveals the degree and nature of hearing<unk> , distinguishing<unk>  from other kinds of hearing<unk> . A<unk>  is characterized by a difference of at least 15 decibels between the air conduction threshold and bone conduction threshold at the same frequency. On an audiogram, the "x" represents responses in the left ear at each frequency, while the "o" represents responses in right ear at each frequency. CT scan Most causes of<unk>  can be identified by examination but if it is important to image the bones of the middle ear or inner ear then a CT scan is required. CT scan is useful in cases of congenital<unk> , chronic suppurative otitis media or cholesteatoma, ossicular damage or discontinuity, otosclerosis and third window dehiscence. Specific MRI scans can be used to identify cholesteatoma.
Conductive hearing loss
Sensorineural hearing loss
Spatial hearing loss
Prelingual deafness
Unilateral hearing loss
Cortical deafness
Auditory exclusion
Noise-induced hearing loss