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HIST 330 Deafness and Technology: Amplification Technologies

This guide discusses some Deaf technologies that DHH people used in the past and use today.


The image shows an audiogram with different colors to indicate hearing levels The image at left shows an audiogram with different colors to indicate hearing levels and is from HearingLife. DHH people use amplification technologies, such as digitally-programmable analog, digital hearing aids and cochlear implants (CI). There are personal and room assistive listening devices (ALDs) that amplify sounds while watching TV, attending classes or lectures, or listening to music. Telephones can be ordered with built-in amplifiers, and there are portable amplifiers one can attach to phones.

Hearing aids and Cochlear Implants are tools and do not replicate normal hearing (particularly for those with sensori-neural deafness), but rather assist the user in utilizing residual hearing. "Hearing Aids are not like Eyeglasses" is a phrase you may come across in understanding the limitations of the amplification technologies. This means some hearing aid users will not experience clarity of sounds. Cochlear implants limit the reception of available hearing frequencies and range.

An audiologist measures a person's hearing level at different frequencies. and is described as mild, moderate, severe or profound and provides an audiogram. These hearing levels do not accurately predict an individual’s skills using speech, language, listening, communication mode, etc. The audiologist will also determine what type of hearing level the person has, ie, sensorineural, conductive (middle ear), or mixed type. A person with sensorineural deafness will find it difficult to discern speech clearly, despite amplification whereas a person with conductive deafness only needs amplification to discern speech clearly--it doesn't affect the perception of speech. Check out the NTID Hearing Center for more information.

Hearing Aid:  They are miniature customized amplifiers and these electronic devices amplify all sounds within close proximity of user.  Since all sound includes background noise, hearing aids function best in quiet environments. There are numerous manufacturers of hearing aids, but all have the same basic components and purpose of amplifying sound. Styles of hearing aids include behind-the-ear (BTE); in-the-ear (ITE); and in-the-canal (ITC). In the past, most hearing aids had analog circuits that processed sound in a linear fashion so that what came in was made louder in equal amounts. Today, most hearing aids are digital and programmable which allows them to be set very specifically based on each individual’s hearing level at different frequencies. Many have special processing capabilities that help improve speech recognition, noise reduction, and overall performance. Many hearing aids include a telecoil (t-coil) or telephone switch that allows the user to access the electromagnetic energy in telephones as well as many publicly available assistive listening devices (ALDs). There is also the option of having a hearing aid integrated with an FM system that does not require direct audio input (DAI) or connection to other devices.

The image shows a man's profile with a cochlear implant above and over the ear. There is also a view of the ear inside showing the cochlear aCochlear Implant: 
This is an option for persons with profound hearing loss who have been unable to benefit from traditional hearing aids.  A cochlear implant (CI) is a surgically-implanted device that converts sound energy into electrical stimuli that can be processed by the auditory nerve. There are specific criteria that must be met in order for a person to be a CI candidate. Most have the ability to connect to assistive listening devices (ALDs) and other external devices.

Telecoil:  (also called a T-coil, T-switch, or telephone setting), installed in a hearing aid or cochlear implant processor, will facilitate the use of many hearing assistive devices. This should be considered at the time hearing aids are purchased. With a telecoil, amplified signals pass through the userʼs hearing aids. Hearing aids are precisely adjusted for the userʼs unique hearing needs and provide better listening than headsets or ear buds.Without a telecoil, a headset or ear buds are required.

ALDs provide the listener with a direct connection to the sound source and help minimize the effects of background noise, distance and room acoustics.  There are both individual ALDs and public or large group ALDs.  All ALDs utilize a transmitter that sends a person’s voice or other sound source to a receiver that distributes the sound evenly throughout a room such as in theaters and churches or directly to an individual. Sound is transmitted in four primary ways:  Frequency Modulation (FM); Infrared (light); Induction Loop (electromagnetic); or through a direct connection. Some hearing aids have a special connection option called Direct Audio Input (DAI) that allows the user to connect directly to an FM system or Induction Loop receiver.  In many instances, one can even connect directly to other devices such as a computer, TV, MP3, iPod, or radio.  

The medical model uses the terms “deaf” and “hard of hearing” to describe individuals with  hearing loss levels. However, an individual may be described as "hard of hearing" but self identifies as Deaf due to cultural values and preferred language use. Conversely, a person may be described as "deaf" but self identifies as "hard of hearing", again based on cultural values and preferred language use.  Many deaf and hard of hearing people do not support the use of terms  such as hearing loss, impairment, or disability. The definitions are explained more fully below.

Deaf: In the adult community, the term Deaf does not describe the hearing level but rather an individual's identification with the Deaf community who use American Sign Language (ASL) to communicate. They may have speech or speech-reading skills in certain situations.

Deafness: The hearing level is severe and affects processing linguistic information through hearing alone, with or without hearing aids. Cochlear implants users are considered medically deaf even though they may function as hard of hearing. Deafness is not dependent on ability to use speech or need to use sign language.

Hard of Hearing: This hearing loss level allows the individual to process acoustic information necessary for auditory-verbal communication, with the assistance of hearing aids and/or ALDs when needed. The  hearing loss level is not an accurate predictor of how one functions auditorily. The audiologic evaluation does not predict the individual's ability to hear with comprehension. Some hard of hearing individuals function very well with hearing aids and ALDs while some may require sign language to understand classroom instruction or conversation, especially in noisy environments.

The information in the columns below is from the Hearing Assistive Technology Online Guide.

Mild to Moderate Hearing Level

A person with a mild or moderate hearing level (may hear in the 25-45 DB range) communicates primarily through speaking and listening. There may be no difficulty hearing enough to communicate easily, but in other situations the person may be challenged.

  • Challenging situations include:
  • Background noise, like machinery, people talking, wind, or traffic noise
  • Some telephones, especially cellular phones
  • Environments that require soft voices and whispering
  • High frequency alert sounds
  • Locating the source of a sound
  • Environments that require the removal of hearing aids and/or hearing protection
  • Large group meetings or classrooms, when the speaker does not use the microphone

Moderate to Severe Hearing Level

A person with a moderate to severe hearing level (may hear in the 40-75 dB range) communicates through speaking and listening with visual information to make up for sounds that are not heard accurately.

  • Challenging situations include those in the previous column and the following:
  • Telephone conversations with standard or cellular phones
  • Large group events and classrooms, even when the speaker uses a microphone
  • Environments with poor lighting
  • Phone conferences with more than one person on the line
  • Alarm clocks and other alert sounds
  • Group conversations
  • Speakers who are not facing the listener or are out of visual range

Severe to Profound Hearing Level

A person with a severe to profound hearing level (may hear in the 70-95 dB range) receives information visually and may use speech to communicate. Visual information will be required to understand accurately. This may include someone with a cochlear implant and people who have become deafened during adulthood.

  • Challenging situations include the previous columns as well as:
  • All telephone conversations
  • Watching videos or training materials without captions
  • One-on-one conversations in average work or school environments


A Deaf person (may hear in the 80-110 dB range) communicates primarily using American Sign Language (ASL) or other visual language system and may have been Deaf since birth or early childhood. S/he may also use speech, but may be most comfortable with a visual language such as ASL.

Challenging situations include all the previous columns.

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