Technical
Info
Digital Technology:
Hearing aids which are fully digital process sound mathematically
bit by bit. In place of electronic components,digital
hearing aids contain millions of tiny electrical parts
manufactured into a single silicon chip. The computer
programmed silicon chip within the aid applies continuous
digital processing to incoming sound.
Here’s how the digital hearing aid works:
| 1 |
The
hearing aid microphone turns sound into an analog
electrical signal. |
| 2
|
A
filter removes inaudible frequencies. |
| 3
|
This
filtered analog signal goes to the analog-to-digital
converter which changes it to a numerical digital
signal so it can be manipulated by the hearing aid’s
internal computer (DSP chip). |
| 4 |
This
chip is programmed to perform many numerical operations
(filtering, noise reduction, loudness compression,
and feedback cancellation) depending on the algorithm
used. |
| 5
|
The
digital signal is converted back into an audible
sound for the patient to hear. These functions are
performed instantly and continually. |
Programmable Technology Hearing Aids:
Programmable circuitry is a feature which allows the
hearing aid to be set-up or adjusted using an external
computer. Advantages are preciseness of electroacoustic
adjustments at the time of the fitting and ease of access
to different types of signal processing for different
listening conditions. Quick comparisons of different
settings can easily be made in order to determine the
wearer's preference. They are not classified as fully
digital.
Advanced Technology Hearing Aids:
Advanced technology hearing aid circuitry employ a more
recent scientific development in amplification electronics
known as non-linear or compression amplification. The
result is a hearing aid with the ability to limit the
level of incoming sound. This delivers a more natural
sound throughout the patient's entire listening range,
without getting too loud or too quiet as can be the
case with conventional hearing aids. Amplifiers used
in advanced technology hearing aids are predominantly
from the Class D family which offer longer battery life
and lower distortion.
Conventional or Analog Hearing Aids:
Conventional hearing aid electronics use basic analog
Class A technology to provide quality, linear-type amplification
to patients with a wide range of hearing losses. Class
A amplifiers have as their defining feature the characteristic
of adding the same amount of amplification to all levels
of sound intensity. Thus, low base sounds will be amplified
with same amount of volume as high treble sounds. Conventional
electronics represent the most basic type of amplification.
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