Topics about Hearing Loss (Click on a topic)
How we Hear
Types of Hearing Loss
Degrees of Hearing Loss
Hearing Aid Technology

• Hearing loss is a world wide problem.
  Experts estimate that one out of ten people suffer from hearing loss.
  
• As hearing gets worse people usually turn to hearing aids as the number one treatment.
  
• Usually they experience improvement to the quality of life as they adjust to wearing a hearing aid.

How we hear

• Outer/External Ear
  
• Collects sounds
  
• Channels sounds through ear canal to the eardrum
  
• Middle Ear
  
• Sounds hitting eardrum create vibrations
  
• Vibrations cause ossicles (3 tiny bones) to move
  
• Vibrations are transmitted to the cohlear
  
• Inner Ear
  
• Inside the cochlear thousands of microscopic hair cells are bent by fluid
  
• Bending of hair cells sets off nerve impulses
  
• Impulses are carried by the auditory nerve to the brain

How sounds are heard:

• Sound Waves hit the eardrum and vibrate through the ossicular chain
  
  
• Incus-malleus-stapes bones (anvil-hammer-stirrup) move in response to sound vibrations and transmit vibrations through the inner ear
  
  
• Sound vibrations enter the fluid-filled cochlea; hair cell nerve endings are rocked by movement of the middle ear bones
  
  
• Sensory cells activate, convert sound waves into electrical nerve impulses; carried to brain by auditory nerve
  
  
• Brain decodes and interprets as the sounds we hear
  
  
• Inner ear is also the center of the “vestibule system”, which helps the body maintain balance

Types Hearing Loss
There are three basic types of hearing loss: conductive hearing loss, sensorineural hearing loss and mixed hearing loss.

• Conductive Hearing Loss
  
  • The problem lies in the outer or middle ear.
    
  • Sound is not conducted efficiently through the outer ear canal to the eardrum and the tiny bones, or ossicles, of the middle ear.
    
  • Conductive hearing loss usually involves a reduction in sound level, or the ability to hear faint sounds.
    
  • Causes include fluid in the middle ear, impacted earwax, a punctured eardrum, and ear infections.
    
  • This type of hearing loss can often be medically or surgically corrected.
    
    
    
• Sensorineural Hearing Loss
  
  • Involves damage to the inner ear or auditory nerves
    
  • Can be caused by several factors, including disease, birth injury, viral and bacterial infections, genetics, head trauma, exposure to loud noise, and aging.
    
  • Involves a reduction in your ability to hear faint sounds, affects speech understanding and your ability to hear clearly.
    
  • This type of hearing loss is permanent; however, it can often be effectively treated with hearing aids.
    
    
    
• Mixed Hearing Loss
  
  • Sometimes a conductive hearing loss occurs in combination with a sensorineural hearing loss.

Degrees of Hearing Loss
The degree of hearing loss refers to the severity of the loss, measured in decibels (dB).

• Normal range or no impairment 0-25 dB
  
• Mild loss 26-40 dB
  
• Moderate loss 41-55 dB
  
• Moderately Severe loss 56-70 dB
  
• Severe loss 71-90 dB
  
• Profound loss 91-110 dB

Degree of hearing loss is determined by an average of three frequency thresholds measured at 500, 1000 and 2000 hertz (Hz).

Hearing Aid Technology
Hearing aids are miniature sound amplifiers to assist persons with hearing loss. They are distinguished by where they are worn:

• In-The-Ear (ITE)
  
• In-The-Canal (ITC)
  
• Completely-In-the-Canal (CIC)
  
• Behind-The-Ear (BTE)

There are three levels of hearing aid technology, commonly referred to as analog, digitally programmable, and digital.

1. Analog - Analog technology has been around for many decades, it offers limited adjustment capability. It is the least expensive.
   
2. Digitally Programmable Analog - (DPA) technology is the "middle grade" technology. These analog circuits can be programmed.
   
3. Digital Signal Processing (DSP) – Digital technology is the most sophisticated hearing aid technology. Digital hearing aids have been widely available since 1996.