Sound Processing Flashcards
How many sound coding strategies offered?
7 sound coding strategies offered
AB offers more ways to hear than any other CI company.
Challenges and Opportunities
Patient Factors
duration of deafness amount of previous hearing age of hearing loss cognitive skills neural survival other
AB’s goal with challenges and opportunities
Remove technology component as a barrier to success and increase each patient’s ability to reach their maximum hearing potential
- through processor and accessory updates
- through new advances in speech coding strategies
What is a strategy
Set of rules and processes for converting the acoustic input signal into electrical stimulating waveforms that are applied as the output by a cochlear prosthesis
Strategy and its effectiveness linked to the sound processor technology and that of the ICS- directly affects how sound info is delivered to the user
Sound Processing Strategies
SAS- Simultaneous analog stimulation MSP- Multiple paired sampler CIS- Continuous interleaved stimulation HiRes-S HiRes-P HiRes-S with Fidelity 120 HiRes-P with Fidelity 120 ClearVoice HiRes Optima-S HiRes Optima-P
Sound Processors with Paired Stimulation
HiRes P
HiRes P with Fidelity 120
MPS
SPs with Sequential Stimulation
HiRes S
HiRes S with Fidelity 120
CIS
SP Strategy goals
- To faithfully represent the characteristics of the incoming acoustic signal to the listener with highest degree of fidelity
- want output of CI system to represent as closely as possible the acoustic input
- To provide a system that’s easy to use with system settings that automatically adjust based on the environment
3 parameters needed to be preserved
Time (temporal)
Frequency (spectral)
Amplitude (intensity)
Temporal representation
For best sound resolution, important to have faithful representation in time domain:
- high fidelity front-end design ensures accurate capture of acoustic environment (capture environment transparently but stimulate it transparently)
- High stimulation rates with HiRes sound allows for detailed delivery of info in time domain, including representation of both envelope and fine structure
Temporal
Conventional strategy vs. HiRes Sound
CONVENTIONAL STRATEGY
- only provides envelope (removes fine time structure)
- sample at slow rate and stimulate at faster rate
- limiting perception of dynamic sounds like music
- reduces ability to hear in difficult listening environments (car, restaurant, etc.)
HIRES SOUND
- preserves fine structure and envelope cues (normal hearing nerve uses this info)
- faster stimulation rate –> more accurate timing cues represented
- sample at higher rate and stimulate at higher rate
- output faithfully represented input with greater detail and definition, giving patient best opportunity to figure out incoming signal.
- HiRes sound provides the clearest, most accurate sound with 5x more resolution than any other CI system.
Why is Temporal info important?
Provides envelope info
- Prosody, intonation, rhythm, and stress
Provides periodicity info
- segmental (manner, voicing, vowels), intonation, stress
Provides fine structure info
- segmental (manner, voicing, place of artic)
- place of artic depends on fine structure
- fast changes in amplitude mark consonants from non consonants
Envelope and fine structure
speech in quiet and music
If speech transmission in quiet is primary goal of CIs, envelope seems most important to transmit.
If music is the goal, fine structure is also relevant
Sequential Stimulation vs. Paired Stimulation
SEQUENTIAL
- Sends electrical pulse to 1 electrode at a time sequentially
- (like playing piano with one hand/finger, only one key at at time)
- Slower rate (reduced pulses/sec)
PAIRED
- 2 electrodes stimulated at 1 time
- delivered to auditory nerve at faster rate
- (like playing piano with 2 hands)
Intensity is influenced by:
-how sound is captured
AND
-how sound is processed by the Cochlear implant system