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AUD spring 2020 CI > Week 3--programming > Flashcards

Week 3--programming Flashcards

1
Q

Typical dynamic range vs that with a CI

A

Typical is 100dB, CI is 10-25dB

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2
Q

3 methods to measure threshold

A

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

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3
Q

Threshold with AB

A

Called T-level

* lowest level detected with 50% accuracy

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4
Q

Threshold with cochlear

A

T-level

Lowest level detected with 100% accuracy

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5
Q

Threshold with med-el

A

Called THR

* highest level with no response

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6
Q

Threshold recommendations for AB and med-el

A

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
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7
Q

Define upper Stimulation level

A

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

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8
Q

Upper stimulation level with ab

A

M-level which is the most comfortable level

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9
Q

Upper stimulation level with med-el

A

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

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10
Q

Upper stimulation level with cochlear

A

C-level and is loud but comfortable

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11
Q

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

A

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

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12
Q

2 ways to measure upper stimulation level

A

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

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13
Q

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

A
  • input dynamic range
  • microphone sensitivity
  • compression
  • channel gain
  • volume control
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14
Q

What is the concept of input dynamic range

A

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

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15
Q

How does cochlear use input dynamic range

A

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

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16
Q

How does med-el use input dynamic range

A

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

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17
Q

How does AB use Input dynamic range

A

It doesn’t have any way to use IDR

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18
Q

Define microphone sensitivity

A

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
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19
Q

Autosensitivity

A

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

20
Q

Compression with CI

A

Is used with an automatic gain control (AGC)

21
Q

Channel gain with CI

A

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
22
Q

Volume control with CI

A

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

23
Q

Interpolation

A

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

24
Q

Sweeping

A

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
25
Q

Loudness balancing

A

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
26
Q

Stimulation rate

A

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
27
Q

Normal maximum pps

A

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

28
Q

Telemetry

A

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

29
Q

Electrode impedance

A 
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
30
Q

Voltage compliance

A

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
31
Q

Frequency allocation

A

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
32
Q

what are coding strategies

A

algorithms to deliver sound

33
Q

who had a big impact on coding strategies

A

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
34
Q

what are the two main types of coding strategies

A
  • continuous interleaved sampling (CIS)

* n-of-m

35
Q

CIS coding strategy

A
  • 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
36
Q

OG coding strategy used by AB

A

*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

37
Q

OG coding strategy used by MED-EL

A

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)

38
Q

HiResolution (HiRes) sound processing

A
  • 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
39
Q

Fine Structure Processing (FSP)

A
  • 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
40
Q

n-of-m coding strategy

A
  • 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)
41
Q

spectral peak (speak)

A
  • 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
42
Q

advanced combination encoder (ACE)

A
  • 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)
43
Q

MP3000

A
  • 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
44
Q

basic comparison of CIS vs n-of-m

A
  • 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
45
Q

simultaneous analog stimulation (SAS)

A

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

AUD spring 2020 CI (16 decks)

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