Diagram of human ear

Introduction to Deafness/Hearing Loss

The hearing mechanism consists of 3 parts—outer, middle and inner ear.  The outer ear is made up of the external ear and the ear canal.  It ends with the tympanic membrane or ear drum. The middle ear is made up of the ear drum and an air filled cavity which contains the 3 tiniest bones in your body, the ossicles.  The inner ear is made up of the semicircular canals (that deal with balance), the cochlea (a shell shaped object the size of a pea that perceives sounds at different pitches) and then the auditory nerve that leads to the brain where sound is perceived.  

Hearing impairments can take on different forms – either a partial loss of hearing or a total loss of hearing referred to as deafness. Hearing loss is categorized as mild, moderate, severe or profound. All have impact upon communication with others. Individuals who are deaf must learn to read lips or learn sign language or cued speech to communicate. Individuals with hearing loss often use technology to compensate. Technology includes hearing aids, FM systems, and cochlear implants. Environmental aids include vibrating alarms, alerting devices, and support dogs.  

There are 3 basic types of hearing loss:




Mixed Hearing Loss

Site of problem

Obstruction in either the outer or middle ear

Problem with the inner ear—many times missing or damaged cilia within the cochlea

Individual has a problem with the inner ear as well as a problem with the outer or middle ear

Possible reasons (not exclusive) for loss

Wax build up, malformation of the cavity, allergies, middle ear infections, etc.

Hereditary hearing loss, hereditary syndrome (Ushers, Waardenberg, etc), diseases or infections, unknown, etc.

Individual with a sensorineural hearing loss combined with wax build-up, middle ear infections, etc.

Results of this loss

Lessening of hearing sensitivity—instead of hearing at a normal level, sound is much softer or not audible

Lessening of hearing sensitivity (the same as conductive)

Distortion of sounds—just as impacting as the lowered thresholds—results in mishearing information (short for sharp, dachshund for oxen, etc)

Lessening of hearing sensitivity + distortion

Medical treatment

Usually treatable—through medication or surgery

Not able to "fix" this hearing loss—can get worse, not better

The conductive component is usually treatable

Educational impact?

Can have an impact

Can have impact—can have difficulty accessing auditory information which can lead to speech and language delays which can result in academic challenges


What is an audiogram?
Audiograms are the plotting of frequency (low to high pitches) and intensity (soft to loud).  Frequency goes across the chart and is measured in Hertz.  A reference point is 1000Hz, which is middle C on the piano.  Intensity goes down the side and it is measured in decibels.  A reference point is 45dB, a typical speaking level.  The audiogram will give you quite a bit of information.  It will tell you the degree of hearing loss—within normal limits (no loss), mild, moderate, severe and profound.  It also gives you the configuration of the hearing loss—a flat loss that just goes across all frequencies, a sloping loss (harder time hearing the high frequency sounds), a reverse slope loss (harder time hearing the low frequency sounds), a cookie bite hearing loss (higher in the extremes; dipping in the middle), etc.  The audiogram will also tell you if it's in both ears or just one (Xs for the left ear, Os for the right) and if it is a conductive, sensorineural or mixed hearing loss.

Hearing Aids and Cochlear Implants
Hearing aids and cochlear implants help people with hearing loss.  A hearing aid can benefit many individuals with hearing loss by amplifying sounds and making the sounds more accessible.  There continues to be tremendous advances in this technology.  The same is true with cochlear implants.  Cochlear implants have more parts than a hearing aid.  There is an implanted part (the implant with electrode array) and an external part (the speech processor).  The cochlear implant works by sending an electrical impulse directly to the cochlea.  Neither hearing aids nor cochlear implants will give normal hearing to the individual—the benefits might be great, however.   FM systems are often used in the school setting.  The teacher will wear a transmitter/mic.  The student will have a receiver that works with the student's hearing aids or cochlear implants.  The teacher's voice will be transmitted through the hearing aid or cochlear implant technology to better enable the student to access auditory information.

American Sign Language and Deaf Culture
Signed languages exist in many cultures.  In the U.S., sign language is referred to as American Sign Language or ASL.  It is considered to be a "complete, grammatically complex language."1 Many individuals who are deaf identify with others who are deaf within an American Deaf culture.  This culture has values, behaviors and traditions that includes rules of behavior in communication, perpetuation of Deaf culture through films, poetry, clubs, athletics and more. For more information on Deaf culture, see Gallaudet University's "About American Deaf Culture."

Do you think you have a hearing loss? 
A good site to visit to hear the different levels of hearing loss and the sounds that are affected by that loss is found at Starkey Hearing Technologies, online hearing test simulatorThe Unfair Spelling Test is also a great tool to realize how distortion can impact speech understanding as well.

1 "About American Deaf Culture." About American Deaf Culture.  Web. 02 July 2015.