Wk12-29-Programming Strategies Flashcards
What is a speech encoding strategy?
The way in which an acoustic stimulus is analyzed, manipulated, and converted into an electrical signal
Speech encoding consists of sending the acoustic signal through a series of _____ filters, feature detection (which relies on the characteristics of the ______), and compression of the dynamic range of the acoustic signal to the dynamic range of the ____ signal.
Bandpass filters
Envelope characteristics
Dynamic range of the electrical signal
What is the ultimate goal of the speech encoding strategy?
To provide a rich and detailed sound experience for the user
What are the 2 types of speech encoding currently in use?
Envelope encoding
Fine-structure encoding
Describe envelope encoding
General outline of sound that reflects changes in loudness (amplitude) over time
Describe fine-structure encoding
Contains more detailed information and reflects changes in pitch (frequency)
- trace the zero crossings up to a certain frequency
What are the 3 categories of speech encoding strategies?
Continuous Interleaved Sampling (CIS)
N-of-M (Peak picking strategies)
Fine Structure Strategies
Describe CIS
- envelope extracted and used to modulate biphasic pulses
- non-overlapping AN stimulation
- used by all device manufacturers in some form
- typical stimulation rates are fairly fast (900-2400 Hz)
Which Speech Encoding Strategy uses the highest amplitude pulses to stimulate certain electrodes?
N-of-M (Peak Picking Strategies)
- analyzes incoming acoustic signal to extract envelope characteristics
- envelope is used to modulate biphasic pulses
- highest amplitude pulses (or loudest parts of speech signal) are stimulated on “N” electrodes out of all the electrodes in the array
*Not all elements of the speech signal get encoded and stimulate the hearing nerve in this type of strategy!!
Describe Fine Structure Strategies
Two types of strategies being used based on frequency:
- zero-crossings in the envelope are used to modulate electrical pulses in the low-frequencies
- envelope encoding is used to modulate biphasic pulses for the mid- and high-frequencies
High Fidelity 120 (P and S) and HiRes Optima (P and S) are current strategies being used with which company?
Advanced Bionics
- used with HiRes90K and Ultra3D implants
- P and S stand for Parallel and Sequential
- High Fidelity 120 is designed to enhance the spectral resolution through current steering
- uses 16 electrode contacts to stimulate “virtual channels”
-HiRes Optima is an update of High Fidelity 120 which enables access to all current processing parameters while improving BATTERY LIFE
Which company uses (has used) ACE, SPEAK, and MP3000?
Cochlear
ACE
SPEAK - older strategy
MP3000 - older strategy
Describe the ACE strategy
- combines frequency resolution of SPEAK encoding strategy with a higher rate of stimulation of CIS (spectral encoding) (ACE uses 500 pps)
- N-of-M strategy by default picking 8 channels of the 22 possible stimulation points
- current stimulation grounds to body of the receiver/stimulator and/or ball electrodes (SPEAK grounds to adjacent electrodes)
Describe the SPEAK strategy
- older strategy developed by Cochlear
- focuses on freq-based info (spectral encoding)
- analysis of incoming signal results in stimulation on channels with eh greatest amount of spectral energy (N-of-M)
- Differs from ACE b/c current stimulation grounds within the cochlea
- usable with all current implants
- uses much slower rates of stimulation (250 pps)
Describe MP3000
- older strategy used by Cochlear
- freq-based info (spectral encoding)
- uses masking principles and analyzes incoming signal allowing for stimulation on channels with the greatest amount of spectral energy (N-of-M strategy)
- *less peaks (max 6) used than SPEAK
- base stimulation rate is 900 Hz per channel
- current stimulation grounds within the cochlea
