Good Vibrations
Every noise sends vibrations, or sound waves, through the air. The vibrations set off a chain reaction when they hit the eardrums.
Part of a fulcrum, the eardrum enhances the vibrations, and bangs against the three smallest bones in your body, connected in a chain - the ossicles.
The first ossicle, the malleus (hammer), then the incus (anvil), and finally, the stapes (stirrup) convert the vibrating sound waves to mechanical waves.
The stapes pass the mechanical waves into a snail shaped tube in the inner ear - the cochlea. The cochlea is the smallest organ in the body, lined with “hair cells” which gather each pitched mechanical wave, convert it to an electrical signal, and send it to the brain..
The brain is where you really hear.
If the outer ear or the middle ear is filled with fluid, ear wax or infection, or if the cochlea or hearing nerve does not perform optimally hearing loss may occur.
Types of Hearing Loss
There are eight types of hearing loss, seven of which are categorized according to the part affected along the auditory pathway. The eighth type (pseudohypacusis) is not connected specifically to a part of the auditory anatomy.
The eight types of hearing loss are:
Conductive – occurs either in the outer or middle ear – common to children and often correctable with medication or surgery.
Sensory – involves damage in the cochlea, typically the inner and outer hair cells or the stria vascularis in the scala media. Typical causes are presbycusis, noise exposure, ototoxic medications, inner ear infections, and heredity.
Neural – affects the auditory branch of Cranial Nerve VIII. Causes include presbycusis, tumors, multiple sclerosis and infection.
Sensorineural – this term identifies hearing loss resulting from both sensory and neural sites, even including the brainstem and cortical pathways. In addition to causes previously described, vascular lesions may cause this.
Mixed – a combination of conductive plus the others.
Brainstem – lesions detected only when the auditory system is affected beyond the cochlea. Hearing tests may indicate normal conductive and cochlear hearing. Causes include vascular accidents, space occupying masses, infection, and demyelinating disease.
Cortical – the lesion is in the temporal lobe or the corpus callosum. Causes may include head trauma, vascular accidents, tumors, and infections.
Pseudohypacusis – hearing loss is exaggerated by the person. More typically than not, a hearing loss is present in one or both ears, but the responses are exaggerated in severity.
Indications You Should See An Audiologist:
Any sudden change in hearing warrants immediate attention
Difficulty hearing conversations, especially in the presence of background noise
Frequently asking others to repeat themselves
Misunderstanding what people say
Difficulty hearing on the telephone
Requiring the TV/radio to be louder than others in the room prefer
Feeling that people are mumbling when they are talking
Difficulty hearing certain environmental sounds
Agreeing or nodding your head when you’re unsure what’s been said in conversation
Removing yourself from conversations because it’s too difficult to hear
Reading lips so you can try to follow what people are saying
Straining to hear or keep up with conversations
Experiencing “Ringing In the Ears” (Tinnitus)
