Week 3--programming

Question 1

Typical dynamic range vs that with a CI

Answer 1

Typical is 100dB, CI is 10-25dB

Question 2

3 methods to measure threshold

Answer 2

1) Hughes west lake (ascending-descending)
2) count the beeps (2-5 beeps altered randomly)
3) psychophysical loudness scale (very soft or just noticeable
* threshold is lowest level detectable 50% of the time

Question 3

Threshold with AB

Answer 3

Called T-level

* lowest level detected with 50% accuracy

Question 4

Threshold with cochlear

Answer 4

T-level

Lowest level detected with 100% accuracy

Question 5

Threshold with med-el

Answer 5

Called THR

* highest level with no response

Question 6

Threshold recommendations for AB and med-el

Answer 6

Don’t actually measure threshold, just set threshold level to 0 or 10% of the upper stimulation level

• this is the result of the use of the continuous interleaved sampling coding method
• –with this method if the threshold level of the CI is audible to the patient they will hear the internal noise of the device

Question 7

Define upper Stimulation level

Answer 7

The maximum amount of electric stimulation that is going to be allowed through
*similar to MPO with hearing aids

Question 8

Upper stimulation level with ab

Answer 8

M-level which is the most comfortable level

Question 9

Upper stimulation level with med-el

Answer 9

Called maximum comfort level (MCL) and is loud but not uncomfortable

Question 10

Upper stimulation level with cochlear

Answer 10

C-level and is loud but comfortable

Question 11

What will happen if the upper stimulation level is set too low

Answer 11

There will be distortion because shrinking dynamic range too much, like having really high compression levels

Question 12

2 ways to measure upper stimulation level

Answer 12

Usually measured using psychophysical loudness scales
* electrical stapedial reflex threshold (ESRT) which is using the CI stimulation to evoke a reflex and then setting the upper stimulation levels at this level

Question 13

5 methods of trying to fit the Dynamic range of hearing into the electric dynamic range

Answer 13

• input dynamic range
• microphone sensitivity
• compression
• channel gain
• volume control

Question 14

What is the concept of input dynamic range

Answer 14

Not everything in the whole dynamic range is important, the really loud stuff could be compressed because we don’t need it so loud,and the really quiet levels can be omitted because they contain a lot of noise
* below 20-35 gets omitted and above 65-90dB gets compressed

Question 15

How does cochlear use input dynamic range

Answer 15

Called instantaneous IDR which focuses on a rang of signals that doesn’t receive compression and the goal is to try and capture speech
*this range is about 40dB and tries to cover the whole range of intensities important to speech

Question 16

How does med-el use input dynamic range

Answer 16

Called maplaw which knows that the threshold level that is set is actually below the threshold level of the patient , so it uses an algorithm to send all the acoustic signal to the upper range of the dynamic range that is set by the threshold and upper stimulation level

Question 17

How does AB use Input dynamic range

Answer 17

It doesn’t have any way to use IDR

Question 18

Define microphone sensitivity

Answer 18

It is the mic gain and is not frequency specific

• the clinical can work with this and the patient can control over this with their remote
• the idea is of the patients bubble, decrease sensitivity to get rid of background noise and increase sensitivity to listen to people farther away

Question 19

Autosensitivity

Answer 19

A feature from cochlear that changes the sensitivity of the microphones based on the noise level going on
*uses Autosensitivity in conjunction with IDR and runs off the concept that if a person is talking they will talk a little louder so the IIDR hovers back and forth with the same 40dB range but in the range that speech and noise would be occurring

Question 20

Compression with CI

Answer 20

Is used with an automatic gain control (AGC)

Question 21

Channel gain with CI

Answer 21

Adding a little bit of current to the signal which makes it a little louder, this is frequency specific because it is per electrode

• just maps the signal a little higher making it a little louder for the patient
• not used with cochlear
• Usually last resort to mess with and patient cannot control this

Question 22

Volume control with CI

Answer 22

Provided to the patient and is done by increasing the USL a little bit and is done across all electrodes so is not frequency specific

Question 23

Interpolation

Answer 23

Instead of mapping each single electrode, you map anchor electrodes and estimate the electrodes in between
*overtime need to map all electrodes but can do for example half at the first appointment and interpolate the rest and hen at the next appointment can map the rest

Question 24

Sweeping

Answer 24

Done at the upper stimulation level from apical to basal electrodes

• present to all electrodes in sequence to ,are sure there is an appropriate progression of pitch and equal loudness perception as well as no side effects like facial stimulation
• problem electrode can be turned off
• can also sweep 50% dynamic range

Question 25

Loudness balancing

Answer 25

Want to make sure the patient is perceiving loudness equally across their array * do two electrodes at a time and alternate presentation between the two and ask the patient if they sound equally loud * then move on to the next pair * normally done at 80-100% of dynamic range * go apical to basal

Question 26

Stimulation rate

Answer 26

Pulses per second * the number of pulses per second which is like cycles per second * often don't use as high a rate as possible or electrode because higher oops mean pitch and loudness will both be perceived higher

Question 27

Normal maximum pps

Answer 27

Generally don't go higher than 1500 pps because it doesn't much Improve speech perception, can go up to 5000 though

Question 28

Telemetry

Answer 28

How the external and internal devices connect, they will either lock(communicate) or fail to lock *electromagnetic transmission back and forth

Question 29

Electrode impedance

Answer 29

``` Opposition to current flow *should be tested every time patient comes into clinic Normally between 1-15kiliohms ---less than shows short circuit ---more than shows open circuit ```

Question 30

Voltage compliance

Answer 30

Is battery capacity or in other words how much current can the battery generate * need too not ask the electrodes to function out of compliance * on software the red ticks on each electrode shows voltage compliance limits for each electrode based off of its impedance

Question 31

Frequency allocation

Answer 31

Tell each electrode what frequency range it will fire to * each manufacturer is different * AB is automatic * cochlear is clinician controlled, but the software will give recommendations * med-el is in between, the clinical can control the lowest and highest frequency stimulated and then select a table of distribution options in the software

Question 32

what are coding strategies

Answer 32

algorithms to deliver sound

Question 33

who had a big impact on coding strategies

Answer 33

Blake Wilson and the Research Triangle Institute (RTI) in North Carolina * developed continuous interleaved sampling (CIS) strategy and the n-of-m strategy in the late 80s and early 90s * developed the current steering concept used to create virtual channels * the use of different stimulus rates at low frequencies

Question 34

what are the two main types of coding strategies

Answer 34

* continuous interleaved sampling (CIS) | * n-of-m

Question 35

CIS coding strategy

Answer 35

* based off of the idea of the processor having different band pass filters, each one allows a portion of the signal coming through to go that route (group of band-pass filters) * there is a rectifier that takes the AC current to a DC current so that the processor can handle the signal * then the signal goes through an envelope detector which is a low pass filter that evaluated the envelope of the signal coming through (200-400 Hz low pass) * typically 800-1600pps with 8-16 channels * uses sequential stimulation originally

Question 36

OG coding strategy used by AB

Answer 36

*took the original CIS strategy and modified it into the MPS which is the multiple pulsatile sampler which is partially simultaneous stimulation and originally had an 8 electrode device that could create 1600pps, but there was a lot of channel interaction

Question 37

OG coding strategy used by MED-EL

Answer 37

took the original CIS strategy and got rid of the rectifier and allowed for virtual channels which allowed stimulation to a wider range of frequencies (used Hilbert transformation instead of rectifier (LPF) ---called their strategy high definition CIS (HDCIS)

Question 38

HiResolution (HiRes) sound processing

Answer 38

* from AB in 2003 * for 16 electrode device instead of 8 * 5156 pps and low pass filter up to 2800 Hz * better AGC * has 2 forms: - --HiResS which is sequential with 2900 pps - --HiResP which is partial simultaneous with 5156pps * better speech rec compared to traditional CIS * 2006 HiRes Fidelity 120 allowed fro current steering (similar speech scores but better music) which is not yet approved for children. This has up to 120 channels * HiRes optima (released with Naida) is the most recent strategy and resulted from the merge of AB and Phonak (not approved fro children yet) - --reduces power consumption by using only virtual channels and wider pulses - --similar outcome, but 51% improvement in battery life

Question 39

Fine Structure Processing (FSP)

Answer 39

* MED-EL * current steering using overlapping bell-shaped filters * Channel Specific sampling Sequence allowed to make the most apical electrodes fire at a rate different from those in the rest of the implant (limited to electrodes 1 and 2) - --because lows are apical, fires 100x per 100 Hz and so on all the way to 350 Hz - -----trying to maintain fine structure - --had better performance for speech and music * fine Structure 4 (FS4) allow the 4 most apical electrodes to fire with the rate of the stimulus up to 1000 Hz * FS4-P) is a modification that uses parallel (simultaneous) stimulation and has a feature to allow for this called channel interaction compensation (CIC) which they claim limits interchannel interaction

Question 40

n-of-m coding strategy

Answer 40

* coding strategy used by cochlear * based off of selecting the number of electrodes to be stimulated * CIS is stimulating all electrodes * with n-of-m the channels without stimulus will be told to be off * M is the maximum number of electrodes * n is the number chose to fire of M (M is always 22 because there are 22 electrodes)

Question 41

spectral peak (speak)

Answer 41

* cochlear's 1st coding strategy * signal goes through bandpass filter, rectification to go from AC to DC, and then n is selected - --this is selected in the software and the processor decides which electrode has the important info and tells those electrodes to fir - --this is the only coding strategy that allows is to manipulate the type of stimulation (monopolar or bipolar) * typically 250 pps * maxima typically 8

Question 42

advanced combination encoder (ACE)

Answer 42

* current coding strategy for cochlear which is similar to speak but allows for a higher rate of stimulation - --total 14400 pps (1800 pps based on 8 maxima) - --recommended rate is 900 pps * typically 8-12 maxima * monopolar * ACE performance is significantly improved for speech outcome over SPEAK * ACE(RE)/HighACE is a modification of ACE to allow higher stimulation rate... is not used often (total 32000 pps)

Question 43

MP3000

Answer 43

* approved but not clinically used yet coding strategy from cochlear * tried to use the technology of MP3 to save battery life by looking at what would be masked by nearby electrodes and skip stimulating those ones because they are unimportant/would not be heard or helpful to the signal coming through (discard unimportant/ low-level input) - --this lead to a smaller processor - --24% improved battery life - --performance with MP3000 and ACE was about the same and MP3000 helped with battery life

Question 44

basic comparison of CIS vs n-of-m

Answer 44

* CIS stimulates all electrodes while N-of-m stimulates the maxima * n-of-m can use higher rate because less electrodes being stimulated, but not used much * less channel interaction with n-of-m * battery life is better with n-of-m normally * performance is similar if not better with n-of-m

Question 45

simultaneous analog stimulation (SAS)

Answer 45

the third coding strategy * from AB and uses analog stimulation * advantage: provides truer speech signal * disadvantage: faster battery drain and higher chance of channel interaction