Ear prostheses

Question 1

Place coding of sound in the auditory cortex

Answer 1

Neurons respond anteriorly to low frequencies, and high frequencies more towards the back of the auditory cortex.

Question 2

For higher frequencies, the place code is valid, but not the ____ coding for individual neurons

Answer 2

Time

Question 3

Brain stem recording
- playing a word e.g. ‘car’

Answer 3

• The brain signal was ran through an audio device to know the sound of electricity in the brain
• Above the chance level, participants could say that the electrical brain sound sounded like the word ‘car’

Question 3

Brain stem recording :
- playing pure tone

Answer 3

Time code of pure tone, frequency of response matches the frequency of the time wave

Question 4

Tonal audiometry

Answer 4

measuring the level of hearing ability

Question 5

Audiogram

Answer 5

Minimal volume needed to hear a sound
- For normal hearing : you can hear every frequency with nearly 0dB
- With mild to moderate hearing loss : you need more dB (40-50dB) to hear sounds, which is missing most speech content

Question 6

Measure of speech understanding and hearing

Answer 6

Measure the percentage of speech that someone can repeat

Question 7

2 types of devices to help hearing loss

Answer 7

1. Hearing aids
2. Cochlear implants (for more severe hearing loss)

Question 8

Hearing aid design

Answer 8

• Sound amplifiers : microphone that picks up sound in the environment and processor that makes it louder in the ear

Question 9

Behind-the-ear (BTE) hearing aid

Answer 9

• Microphone and electronic chip sitting behind the ear
• Loud speaker inside the ear

Question 10

In-the-ear (ITE) hearing aid

Answer 10

• Block the ear with the device and processing chip
• Not always the best solution because creates occlusion

Question 11

Hearing aids and programming software

Answer 11

Knobs on the programming software increase the volume or the acoustic gain for the specific frequencies that need more volume, creating a gain curve

Question 12

Hearing aid fit check : Validation of acoustic output at the tympanic membrane

Answer 12

With a computer
- Increase the volume on the device
- Check with a probe microphone located at the eardrum to validate that the volume that is being delivering there is indeed what is prescribed.

Question 13

Directional microphones

Answer 13

Allow to focus on speech

Question 14

Noise-cancelling algorithms

Answer 14

Cancel background noise

Question 15

True or false : there are prescription hearing aids and Over-the-counter (OTC) hearing aids

Answer 15

True

Question 16

Cochlear implant

Answer 16

1. An external microphone picks up sounds from the environments, transduces them into a firing pattern, and transmits them to the magnet on the skull
2. The signal is then sent to the implant under the skin, which sends it along the electrode in the cochlea
3. The electrode with many stimulation points shoot electricity on the nerve along the basilar membrane of the cochlea (from base to apex)

Question 17

Candidacy for cochlear implant

Answer 17

> 60 dB of hearing loss
< 60% of speech recognition

Question 18

Can we combine cochlear implants and hearing aids ?

Answer 18

Yes
Example :
Mild hearing loss at 500Hz, but complete hearing loss starting at 1500Hz
Solution :
- Hearing aid for low frequencies
- Cochlear implant for high frequencies

Question 19

Electro-acoustic stimulation (EAS)

Answer 19

Low pitches : acoustic stimulation of loudspeaker
- Will go through natural pathway of sound, but amplify with a loud speaker inside the ear to fix the mild hearing loss at these frequencies
- The sound will go where the low frequencies are place coded : at the apex of the cochlea
High pitches: electric stimulation of cochlear implant
- Insert electrode inside the ear, and send electricity right on the nerve to restore hearing

Question 20

Profound sensorineural hearing loss

Answer 20

Equivalent to not hearing anything at all
E.g. does not hear anything below 85-90dB and can only repeat 10% of 100dB speech

Question 21

Maximal cochlear duct coverage improves sound _____

Answer 21

Quality

Question 22

High pitch sounds and cochlear implants

Answer 22

Just after activation of the cochlear implant, people report more high-pitched sound because the cochlear implant transfers sounds only at the entrance of the cochlea where the high pitched sounds on the nerve are coded.
Later, people do not report hearing high pitched sounds because they got used to the cochlear implant.

Question 23

Anatomy-based fitting

Answer 23

• Using CT scan to locate the electrode
• Trying to match the frequencies that we send to the electrodes to match them to what the hearing nerve is meant to hear at the particular location

Question 24

Folding of cochlear implant in left ear with a place coding that’s meant to fit the whole cochlea will create ...

Answer 24

mismatch between left and right ear

Question 25

Solution to folded cochlear implant in one ear

Answer 25

Solution : ABF to trade off a full delivery of sounds (cut off base sounds) for a match across both ears

Question 26

ABF improves ... in experienced bilateral CI users

Answer 26

speech recognition in quiet and in noise

Question 27

Hearing handicaps in single-sided deafness

Answer 27

- Recognition deficit for speech signal in the ipsilesional auditory hemifield for the dead ear side - Speech-in-noise recognition deficit - Sound localization deficit Pupillometric measure of listening effort : pupil dilates with higher cognitive effort

Question 28

ABF improves speech recognition ... in experienced CI users with single-sided deafness (Kurz et al., 2024)

Answer 28

in noise, but not in quiet,

Question 29

ABF improves speech-in-quiet recognition in patients newly implanted with a ...

Answer 29

unilateral EAS CI

Question 30

A proper place coding does good only for patients with...

Answer 30

a reference (either another healthy ear or normal hearing inside the ear beside the cochlear implant) Does not help in bilaterally deaf patents newly using a unilateral CI

Question 31

Anatomy-based fitting improves _____ perception in bilaterally deaf patients using a unilateral CI

Answer 31

Music - Subjective quality rating of music samples - Melodic contour identification - Familiar song appreciation

Question 32

There is time coding only for the low pitch sounds at the ____

Answer 32

Apex

Question 33

Continuous interleaved sampling (CIS)

Answer 33

All neurons with a cochlear implants will fire with a steady electric pulse rate, and depending on the intensity of acoustic waves, the voltage will increase and decrease.

Question 34

Fine temporal structure processing (FSP)

Answer 34

More moderns approaches of coding the sound will make sure the signal sticks to the temporal architecture of the wave inside the envelope of the sound signal.

Question 35

FSP fails to improve ... in bilateral deaf patients with a newly-implanted or experienced unilateral CI

Answer 35

- speech recognition in quiet or in noise - melody discrimination

Question 36

introduction of unilateral acoustic input in unilateral CI users (EAS) improves ...

Answer 36

speech recognition in quiet and in noise

Question 37

Fine structure processing improves _____ perception in experienced unilateral and bilateral CI users

Answer 37

Music - Improved detection of filtered low frequencies

Question 38

Tinnitus

Answer 38

With hearing loss, the nerve receives less stimulation, but a compensatory mechanism from the cochlear nucleus in the brain stem to the auditory cortex is going to increase the volume in the brain.

Question 39

When we fix someone’s hearing loss, do we also fix their tinnitus ?

Answer 39

Yes, Tinnitus level is measured with Tinnitus Handicap Inventory (THI) (from 0 to 100) and it decreases with cochlear implant