Diagnosis of hearing loss
How does hearing work
Hearing can be defined as the process of sound traveling through one’s outer, middle and inner ear. Although sound enters through one’s ear, it is interpreted by the brain. For this interpretation to take place, one’s ear and auditory nervous system follows a series of complex steps that transforms sound waves in the air into electrical impulses.
This article talks about types of hearing loss, diagnosis of hearing loss, hearing loss in adults and hearing loss in children.
The parts of one’s auditory system are:
Outer Ear
It consists of the pinna, the external part of one’s ear which is visible and the ear canal.
Middle Ear
It consists of the eardrum (tympanic membrane) and three tiny sound conducting bones called ossicles. These three bones are named after their shapes - malleus (hammer), incus (anvil) and stapes (stirrup).
Inner Ear
It consists of the spiral-shaped cochlea and the hearing nerve (tiny hair cells, as well as semicircular canals that help in maintaining balance.
Auditory Nervous System
The auditory nervous system runs from the cochlea to a station in one’s brain stem known as the nucleus. From this station, electrical impulses travel to one’s temporal lobe, where the brain gives meaning to the sound waves.
For successful hearing to take place, the following steps are performed by the parts of the ear and auditory nervous system:
- Sound waves travel through one’s ear canal to the eardrum and cause it to vibrate
- The vibrations travel down the eardrum to the ossicles
- One’s ossicles then send the vibrations to the cochlea
- The tiny hair cells or hearing nerves in cochlea vibrate and send electrical impulses to the auditory nerve
- One’s brain actively receives these electrical impulses and transforms it into sound
Slightest of problems in this process, may cause one to experience hearing loss.
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Benefits of binaural hearing
The benefits of binaural hearing or hearing from both ears can be listed as:
- Helps to avoid the head shadow effect
- Helps to understand speech in noise
- Helps to locate sound
- Improves sound quality
- Reduces listening efforts
- Increases listening range
Types of Hearing Loss
Sensorineural hearing loss occurs when one’s inner ear (cochlea) or auditory nerve gets damaged. This type of hearing loss is commonly caused by exposure to loud noise, genetic factors, congenital hearing loss, aging, head injury, adverse reaction to medication or any sort of ailment.
High-frequency hearing loss occurs when one has difficulty with hearing high pitched sounds. It is commonly caused by aging, exposure to loud noise, middle ear infection, genetic factors, tumors, congenital hearing loss, head injury, adverse reaction to medication or Meniere’s disease.
Single-sided deafness or unilateral hearing loss occurs when there is little or no hearing in one ear, but normal hearing in the other ear. This type of hearing loss is commonly caused by viral infections, illness, adverse reaction to medications, head trauma or ear injuries.
Conductive hearing loss occurs when one’s outer ear middle ear is damaged. It is commonly caused by congenital anomaly (like Microtia and Atresia), syndromes (like Down, Goldenhar and Treacher Collins), middle ear infection, cholesteatoma, draining ears, chronic ear infection, previous ear surgeries or benign tumors.
Mixed hearing loss occurs when one has a combination of both sensorineural and conductive hearing loss.
Degrees of hearing loss
Comprehending the degree of hearing loss is crucial for diagnosis of hearing loss and to determine the right treatment for one. The degrees of hearing loss are commonly classified as:
Mild Hearing Loss
One may hear speech, but deciphering soft sounds is difficult.
Moderate Hearing Loss
One may hear the other person speaking at a normal level, but would find it difficult to understand what he / she is actually saying.
Severe Hearing Loss
One may hear little to no speech of the other person talking at a normal level and only some loud noise.
Profound Hearing Loss
One fails to hear any sort of speech and only responds to very loud sounds.
Signs of hearing loss in adults
- Straining to hear
- Difficulty in keeping up conversations
- Asking others to repeat what they said
- Difficulty to hear in the presence of background noise
- Mishearing what others said
- Agreeing or nodding when not sure of what is being said
- Reading lips to understand what is being said
- Difficulty in hearing on the phone
- Turning up the volume of radio or television louder
- Feeling that others are mumbling while they talk
- Failing to hear natural sounds (like rain falling or bird chirping)
- Constant ringing or buzzing sound in the ear
- Difficulty in hearing on one side
- Difficulty in telling where sounds are coming from
- One’s own voice starts to sound different
- Feeling pain or pressure in one or both ears
Signs of hearing loss in children
- No reaction to loud sounds
- Not seeking out or detecting where sound is coming from
- Stopped babbling or trying to make sounds
- No reaction to voices, even when being held
- Ear is missing or congenital anomaly
- Difficulty in following simple commands or understanding directions
- Easily frustrated
- Experiences communication breakdowns
- Lacking with speech and communication skills
- Failing to understand what others are saying, unless directly looking at them
- Exhausted from concentrating to understand speech at school
- Displays signs of behavioral problems or social difficulties
- Difficulty in keeping up at school
