Sound Processing

Question 1

How many sound coding strategies offered?

Answer 1

7 sound coding strategies offered

AB offers more ways to hear than any other CI company.

Question 2

Challenges and Opportunities

Patient Factors

Answer 2

duration of deafness
amount of previous hearing
age of hearing loss
cognitive skills
neural survival
other

Question 3

AB’s goal with challenges and opportunities

Answer 3

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

Question 4

What is a strategy

Answer 4

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

Question 5

Sound Processing Strategies

Answer 5

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

Question 6

Sound Processors with Paired Stimulation

Answer 6

HiRes P
HiRes P with Fidelity 120
MPS

Question 7

SPs with Sequential Stimulation

Answer 7

HiRes S
HiRes S with Fidelity 120
CIS

Question 8

SP Strategy goals

Answer 8

• 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

Question 9

3 parameters needed to be preserved

Answer 9

Time (temporal)
Frequency (spectral)
Amplitude (intensity)

Question 10

Temporal representation

Answer 10

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

Question 11

Temporal

Conventional strategy vs. HiRes Sound

Answer 11

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.

Question 12

Why is Temporal info important?

Answer 12

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

Question 13

Envelope and fine structure

speech in quiet and music

Answer 13

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

Question 14

Sequential Stimulation vs. Paired Stimulation

Answer 14

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)

Question 15

Intensity is influenced by:

Answer 15

-how sound is captured
AND
-how sound is processed by the Cochlear implant system

Question 16

Intensity and T-Mic2

Answer 16

• valuable cues about sound source and location
• improved speech understanding in noise
• natural use of most popular headsets

Question 17

Intensity-

2 features of AutoSound

Answer 17

Dual-Action Automatic Gain Control (AGC)
•soft sounds remain audible, louder sounds loud but comfortable and not too loud

Wide Input Dynamic Range (IDR)
•access to softer elements preserved and compression is limited
•determines how much of sound captured by processor is mapped into recipient’s electrical dynamic range (EDR)- range between programmed thresholds (Ts) and comfort levels (Ms)

Question 18

Intensity-

Advantages of AutoSound

Answer 18

• enables recipient to hear from whisper to shout without processor adjustments (access to sound in all environments automatically)
• Can go into variety of listening situations without worrying about missing out
• improved access to softer speech
• natural hearing for incidental learning and awareness of environment
• better hearing in challenging acoustic environments

Question 19

Spectral-

Importance of Fine spectral resolution

Answer 19

Research suggests while 4-12 filter assignments are sufficient for speech, significantly more are required for understanding in noise and music.

• hearing in real (messy) world
• hearing in noise
• music appreciation
• environmental sounds
• tonal languages

Question 20

Spectral-

Frequency bands

Answer 20

After sounds are captured, complex sound info is divided into frequency bands to be mapped across electrode array.

• CIs process essential same frequencies (250-8000 Hz)
• Processing within this range can be substantially different

-AB HiRes: 16 bands
CIS: 8 bands

-Cochlear ACE: 22 bands, but entire sections of spectral fingerprint of sounds are dropped

Question 21

Spectral Resolution for Speech

Answer 21

Not as much resolution needed for speech understanding

• speech cues relatively robust in frequency domain
• even if formants are a little ‘sloppy’, vowels can still be distinguished

Question 22

Spectral Resolution for Music

Answer 22

Difficult since targets are points, not ellipses in frequency space

• have to get much further away from original note to stimulate new area that assigns a new filter
• (2 notes close on piano would sound the same)
• (Why music not heard or appreciated as well as could be)

Question 23

Spectral Resolution-

Fidelity 120

Answer 23

multiple independent current sources allow for steering of current between physical electrode contacts to deliver added spectral information (up to 120 unique pitch percepts)

• F120 aids with hearing in the real world, hearing in noise, music appreciation, hearing environmental sounds, and understanding tonal languages
• AB is only company that has implemented way to put current beyond physical electrode contacts; delivering current up to 7 unique pitch percepts between each electrode pair

Question 24

Spectral Resolution-

HiRes Optima

Answer 24

• New compliance voltage 4V (versus 8V for F120)
• AutoVoltage FR management
• New default pulse width: APW II
• New current steering paradigm delivers stimulation ONLY between physical electrode contacts
• 53% improvement in battery life
• amount of current needed to produce intermediate pitch sensation is same as current delivered to single physical electrode; HOWEVER, lower current levels per physical electrode are needed to generate intermediate pitch sensations

Question 25

ClearVoice

Answer 25

Sound processing strategy identifying channels where unwanted sound is present, and attenuates transmission in those channels to enhance the SNR - Designed to improve listening in complex environments while maintaining same great performance in quiet - Improve overall SNR, enhancing designed signal - Particularly effective with steady-state sounds.

Question 26

ClearVoice- available for use with which sound processors?

Answer 26

Harmony, Neptune, and Naída when used with CII or HiRes 90K

Question 27

ClearVoice and modulated noise

Answer 27

Modulated noise- acoustic waveform with temporal modulations (multiple people talking) - Modulated noise and reverberation- much like steady-state noise following reflections in a room

Question 28

ClearVoice settings and maximum attenuations

Answer 28

low, medium, high For a given setting, more attenuation is applied in a channel as the estimated SNR for that channel decreases Maximum Attenuations Low- 6 dB Medium- 12 dB High- 18 dB

Question 29

Why use ClearVoice?

Answer 29

- significantly improves speech understanding in steady-state noise - significantly improves speech understanding in multi-talker babble - provides same great performance in quiet - preferred by most subjects (93%) for everyday listening - Almost all subjects benefit from ClearVoice (98%) - All subjects (100%) like and would use ClearVoice.

Question 30

M-Level

Answer 30

most comfortable loudness level

Question 31

IDR

Answer 31

determines how much sound captured by the processor is mapped into recipient's electrical dynamic range