Final Study Guide Part II

Question 1

external components of a cochlear implant system

Answer 1

microphone
digital speech processor
cord
external Transmitter / Coil / Head Piece/ Transmitting Coil
magnet
power source

Question 2

Picks up acoustic signal and converts to an electrical signal for input to the speech processor

Answer 2

mic

Question 3

Converts the microphone input (electrical signal) or other input into patterns of electrical stimulation

Answer 3

digital speech processor

Question 4

Delivers the electrical data

Answer 4

cord

Question 5

Delivers the electrical data to the internal receiver (antenna) through radio frequency

Answer 5

External Transmitter / Coil / Head Piece/ Transmitting Coil

Question 6

Locates and maintains connectivity between the external and internal components

Answer 6

magnet

Question 7

Internal Implant components

Answer 7

internal magnet
internal receiving Coil / Transmitting Coil / Internal Antenna
internal electronics package
electrode elads
electrode array
electrode contacts

Question 8

Maintains connectivity with the external transmitter

Answer 8

internal magnet

Question 9

Receives digital signals from the external transmitter and converts them into electrical impulses
Transmitted through radio frequency

Answer 9

internal receiving Coil / Transmitting Coil / Internal Antenna

Question 10

housed in a biocompatible titanium case

Answer 10

Internal Electronics Package

Question 11

Receives signals from the speech processor and converts them into electric impulses

Answer 11

Digital signal processor (inside internal package)

Question 12

For electric pulse generation
Decodes, analyzes and delivers data to the electrode array

Answer 12

stimulator (in internal package)

Question 13

Receiver/Stimulator

Answer 13

Includes the internal coil, digital signal processor & stimulator

Question 14

Delivers the electric current (pulses) from the stimulator to the electrode array housed in the cochlea

Answer 14

Electrode Leads

Question 15

Housed in the cochlea
Stimulates the auditory nerve fibers in the cochlea
Includes multiple electrode contacts (e.g., 12-22)

Answer 15

Electrode array

Question 16

how does a cochlear implant convert sound into electrical stimulation, step-by-step, from sound pickup to nerve stimulation?

Answer 16

Microphone on the speech processor sitting behind the ear picks up the acoustic signal which converts it into electrical information, amplifies it, and sends to the speech processor
The speech processor cleans up and converts the electrical signal into digital signals to be sent to the external transmitting coil
The external transmitting coil sits outside on the skin and sends the digital signal information and power by radio frequency through the skin to the implant inside and its internal receiver
The internal receiver/stimulator decodes the digital signal and creates and sends electrical pulses to the electrode array in the cochlea via the lead
The electrode contacts? In the array stimulate the auditory nerve fibers with controlled electrical impulses for the brain to interpret as sound
*Amplitude, duration, and rate of the pulses are controlled by the speech processor

Question 17

Simple explanation for a PT

Answer 17

CI helps you hear by turning sounds into electrical signals the brain can understand
To do so the tiny mic behind your ear picks up the sounds and sends it to a small computer called the processor that turns it into a special signal that is sent to the implant under your skin
This implant then sends the signal to tiny wires inside your inner ear to stimulate your hearing nerve which is sent to the brain and it turns them into sound
It doesn’t make your hearing normal but it can help you to hear and understand speech better. It takes time and practice to get used to and regular f/u appointments and listening therapy to get the best results

Question 18

Basic CI Operations

Answer 18

Sound is picked up by the microphone (acoustic & BB/Complex) and converts it to an electrical signal
The electrical signal is sent to the preamplifier to increase the amplitude of the signal to improve SNR for further processing (step 1)

filtering: uses fourier analysis to break down complex sound into simpler pieces (frequency bands/analysis bands/channels) with digital filters (frequency filtering banks) through specttral analysis, uses bandpass filters to divide the sound into frequency bands that correlates with a specific electrode in the cochlea which helps to mimic normal tonotopicity of cochleas

envelope detection: envelope of the decomposed signal is generated with rectification (flipping sound all +) and low pass filtering (smooths out the signal and looks at loudness) in each frequency band and this envelope information (how sound changes in loudness) is sent to the electrodes as an electric current

compression: the enveloped signal takes the WDR of the input and shrinks it into the implant range to stimulate the nerve (normal DR 0-120 & EDR is about 25dB) - boosts soft sounds and turns down loud sounds

modulation: After sound is split into bands, filtered, and compressed, the CI turns that information into something the brain can understand which is done by creating electrical pulses. Takes the amplitude (loudness) from each frequency band and uses it to train biphasic electrical pulses (quick bursts of electricity)

Question 19

What role does the Fourier analysis concept play in the function of the CI speech processor?

Answer 19

Central to the filtering stage of CI speech processors
Fourier analysis allows the processor to “understand” complex sounds by simplifying them into individual frequencies, each of which can be sent to the correct place in the cochlea for the brain to interpret
Breaks down complex sounds into component sine waves (frequencies)
Allows the processor to identify what frequencies are present, how strong they are and how they change over time
Mimics how a natural cochlea analyzes sound through tonotopicity

Question 20

wireless communication between the external sound processor and the internal implant, allowing clinicians to monitor, test, and adjust the implant’s function
Receiving data from the implant to ensure that it works within the specifications

Answer 20

telemetry

Question 21

nonphysiological measures

Answer 21

impedances
device function and current fields

Question 22

physiological neasures

Answer 22

neural measures
ECAP (electrically evoked compound action potentials)

Question 23

what is electrode impedance

Answer 23

measure of opposition to electrical current flow across an electrode when a certain voltage is applied

Question 24

Rate at which electric charge (ions or electrons) passes a given point (the passage of electrons in a conducting material). It is measured in amperes
Needed to stimulate the tissues

Answer 24

current

Question 25

current

Answer 25

actual substance that is flowing through the wires of the circuit

Question 26

Potential difference between two points in an electric circuit (the energy that are required to accelerate electrons from one point to another)

Answer 26

voltage

Question 27

voltage

Answer 27

Force that pushes the current through the circuit

Question 28

Occurs when electrons collide with atoms and lose energy

Answer 28

resistance

Question 29

resistance

Answer 29

friction that impedes flow of current through the circuit

Question 30

higher impedance =

Answer 30

higher current & higher voltage

Question 31

Clinical Uses for Impedance Measures

Answer 31

Identify electrode failures for the programming of the sound processor Verification of voltage compliance Monitoring electrode function over time for clinical management Evaluate intraoperative to postoperative changes Monitor changes across f/u visits