We hear thanks to soundwaves, an acoustic energy, that vibrates the eardrum causing the ossicles (three small bones in the middle ear) behind the eardrum to move and transmit sound to the cochlea, the organ of hearing.
Mechanical energy from the movement of ossicles moves the hair cells in the cochlea. The movement of hair cells converts the mechanical energy into electrical energy. Fun fact: We have 3,500 inner hair cells and 12,000 outer hair cells!
Once the mechanical energy is converted to electrical energy, the signal travels to the auditory cortex in the brain. The brain then synthesizes the information received and attaches meaning to the sound.
There are three types of hearing loss: Conductive hearing loss, sensorineural hearing loss and mixed hearing loss.
Conductive hearing loss happens when sound can’t travel to the cochlea. This can be caused by ear wax buildup, foreign bodies, a hole in the eardrum, ear infection, cholesteatoma (a skin-lined cyst or growth in the middle ear) or erosion or dislocation of the ossicles.
Sensorineural hearing loss happens when there is the damage to the organ of hearing due to age, noise trauma, ototoxic drugs, autoimmune disease, infections or tumors involving the hearing nerve.
Mixed hearing loss is a combination of conductive and sensorineural hearing loss.
Hearing loss is characterized by the type of hearing loss (conductive, sensorineural or mixed) and the severity. Hearing loss severity is ranked into categories:
- Mild hearing loss is when you have difficulty understanding soft speech, especially in a noisy environment.
- Moderate hearing loss is when you experience difficulty understanding normal speech, especially in a noisy environment.
- Moderately severe hearing loss is when you need speech to be loud and have difficulty hearing with background noise in groups.
- Severe hearing loss is when you can’t hear normal speech and sometimes have difficulty with loud speech.
- Profound hearing loss is when you have difficulty with very loud speech and sometimes can’t hear loud speech at all.
When there is hearing loss, the listener misses some of the speech sounds and as a result, the brain receives an incomplete message. Hearing loss is sometimes like playing Wheel of Fortune when you’re missing some of the letters. When the listener is missing some of the sounds of speech, other parts of the brain start to take over to utilize visual cues and context to decode the message. The brain is highly sophisticated in its ability to synthesize information, however, when the brain shifts resources away from the auditory cortex to other areas of the brain, disuse leads to atrophy in the auditory cortex.
Symptoms of hearing loss can include:
- TV volume is too loud for others
- Frustrated in noisy settings
- Being told you talk too loudly
- Feeling tired at the end of the day
- Blaming others for mumbling
- Asking others to repeat themselves
Hearing loss is often associated with several other health conditions, including cardiovascular disease, diabetes, tinnitus, safety/balance, smoking, isolation, dementia and hypertension.
If you suspect a hearing loss, the first step is to make an appointment with a Mercyhealth audiologist for testing and evaluation. Audiology testing is painless, comfortable and safe. It includes checking your ability to recognize everyday words at different volume levels and to hear various tones.
Dr. Mary Agulo earned her Doctor of Audiology degree at Rush University in Chicago. She is a member of the Illinois Academy of Audiology. She sees patients at Mercyhealth Hospital and Physician Clinic–Crystal Lake. For more information, call 815-356-7494.