Download Hearing Aids

Hearing Aids
Bernycia Askew
Who they’re for
 Hearing Aids are usually best for people who have a mildmoderate hearing loss.
 They are often benefit those who have contracted noise
induced hearing loss with age and have a high frequency
loss
 While those who can be considered legally deaf can acquire
hearing aids, the will usually suffer from a extreme sensorineural hearing loss and would benefit more from a cochlear
implant.
 Often recommended to people when there is noticeable
difficulty understanding speech.
Pure Tone Testing
 Air Conduction- used to measure the ability of hearing
from the outer and middle ear. Done with headphones
place over Outer Ear or inserted into the ear canal.
 Bone conduction- Measure of inner ear through bone
conduction. Tone sent directly through temporal bone to
the inner ear.
Hearing Testing

Some of the basic measurements when fitting a person for a hearing aid

Puretone Average (PTA) After pure tone air conduction responses have been recorded for
each ear, the responses at 500 Hz, 1000Hz and 2000 Hz are averaged and recorded in the
summary chart of the audiogram. Measured in decibels (dB).

Most Comfortable Listening Level

Uncomfortable Listening Level

Speech Recognition Threshold (SRT)- The Speech Recognition Threshold (SRT) is
measured in decibels (dB), Two-syllable words, called Spondee Words, are presented to the
client. The SRT is defined as the lowest hearing threshold level at which 50% of a list of
Spondee Words is correctly identified for each ear.

Word Discrimination score (WD)- is based on the percentage of words correctly understood
when presented at MCL or at a normal conversational speech level (40dB-60dB).
-
Types of Hearing loss
 Conductive- mechanical issues in outer or middle ear
 Sensorineural hearing loss- Damage to the cochlea or
auditory nerve, permanent.
 Mixed Hearing loss- a combination of conductive and
Sensorineural hearing loss.
Hearing Aid Parts
 Microphone- picks up sound from the environment
and converts it into an electrical signal, which it sends
to the amplifier
 An Amplifier- increases the volume of the sound and
sends it to the receiver.
 A receiver/speaker- changes the electrical signal back
into sound and sends it into the ear. Then those
impulses are sent to the brain.
 A battery-provides power to the hearing aid.
Digital vs. Analog

Analog hearing aids amplify sounds -- the trouble is
they amplify all sounds equally. Conversational speech
is obstructed by other “back ground noise” (like the
television, or a vaccumm cleaner) Some analog
hearing aids are programmable, meaning that they can
hold separate settings for different listening situations.
You can "change the channel" to adjust certain sounds
louder or softer, depending on your preferences and
hearing loss. They aren't as sensitive as digital hearing
aids.
Styles
 Behind the Ear
 In the Ear
 In the canal
 Completely in the canal
 Hearing aid size can correlate to the amount of loss a
person has. Smaller hearing aids have smaller
batteries, and are better for those with a mild/moderate
loss whereas bigger aids are for more severe cases
because they have more power to amplify sound.
Bone conduction HA

External bone-conduction hearing aids function by transmitting sound waves through the bone
to the ossicles of the middle ear. New technology have also allowed for the BAHA Implants that
Allow vibrations to go directly to the Inner ear.

Air-conduction hearing aids require the use of ear molds, which may be problematic in patients
with chronic middle ear and ear canal infections or an ear canal that cannot accommodate an
ear mold. bone-conduction hearing aids may be an alternative.

A titanium post is surgically attached to a bone behind the ear. The sound processor attaches to
the post and transmits sound vibrations through external abutment to the titanium implant. The
implant vibrates in the skull and inner ear, stimulating the nerve fibers of the inner ear and
allowing the individual to hear.
Some issues….
 Feedback- a squealing/whistling caused by sound
(particularly high frequency sound) leaking and being
amplified again, may be a problem for severe hearing
losses.
 To High of a Gain- The ideal Gain for a person is ½ to
1/3. If the fitting of the hearing aid doesn’t suit the
hearing loss, or if there is too much amplification, the
hearing aid can actually cause noise induced hearing
loss.