This document discusses the effects of hearing aids and cochlear implants. It explains that hearing aids amplify weaker sounds to make them audible, while cochlear implants generate acoustic sensations to bypass hearing loss. Hearing aids can shape amplification based on the individual's audiogram, amplifying more where hearing is worst. In contrast, cochlear implants provide a basic representation of sound but cannot restore full hearing. Both technologies improve speech perception for those with hearing loss.

1. Understanding the effect of hearing aids and cochlear implant
Roberto Ballerini

2. audiogram
You all already saw an
audiogram!

3. audiogram
It is usually used to
visualize a hearing loss

4. audiogram
A mild one as this…

5. audiogram
…or a profound one as
this

6. audiogram
It is perhaps more simple
to understand it
upside-down

7. audiogram
Now the louder sounds
are up!

8. audiogram
And the sounds we can
hear are over the red
line

9. audiogram
With my mild deafness
on high frequencies, I
hear well almost all
speech sounds

10. audiogram
The right ear of my
daughter only hears an
airplane taking off at
20 meters!

11. cochlear implant
The effect of the
implant:
do notice that some low
and high frequencies are
missing

12. cochlear implant
Do remember that young
people can hear from 20
to 20,000 Hz

13. cochlear implant
Audiometries, instead,
usually test from
125/250 to 4,000/8,000 Hz

14. cochlear implant
Luckily the main
informative content of
speech is in the central
part!

15. hearing aids
Left ear of my daughter
hears slightly better!

16. hearing aids
She can wear
a hearing aid!

17. hearing aids
Cochlear implant is a
sound synthesizer: it
generates acoustic
sensations

18. hearing aids
Hearing aids are
amplifiers: they make
stronger the weaker
sounds

19. hearing aids
Implant lowers our red
line

20. hearing aids
Hearing aids raise the
weaker sounds in our
audiogram

21. hearing aids
Whispers raise from 20
to 80 dB, as an example

22. hearing aids
I stretched it a bit too
far… my daughter
can’t hear whispers

23. hearing aids
But she’ll hear a good
share of the speech
banana sounds

24. hearing aids
Warning: I made a
simplification!

25. hearing aids
I moved up the banana
the same quantity at
every place!

26. hearing aids
Modern hearing aids can
change its shape…

27. hearing aids
Giving a higher
amplification where my
hearing is worst

28. hearing aids
Second simplification: I
amplified strong and
weak sounds the same
way

29. hearing aids
I can’t really do it:
I’d break the eardrum!

30. hearing aids
So if a sound is already
strong, I don’t amplify
it!

31. hearing aids
The airplane stays at
the same place. The
whispering goes up near
the airplane!

32. hearing aids
So the real effect is
similar to this:

33. hearing aids
If the hearing loss is
severe or profound, I
need to amplify a lot

34. hearing aids
And if I amplify a lot
the weak sounds and not
at all the strong ones…

35. hearing aids
The difference that I
perceive between strong
and weak sounds is a lot
weaker

36. hearing aids
Last peculiar case: I
have a «hole» at some
frequency

37. hearing aids
Digital hearing aids can
«move» the sound
frequency

38. hearing aids
If I miss the high, I move
them towards lower
frequencies!

39. hearing aids
Like that !!!

40. Thanks!!
Roberto Ballerini
roberto.ballerini.work@gmail.com