This document summarizes research on cochlear implants conducted in New Zealand. It discusses improvements in speech perception over time for implant users, changes in the auditory brain measured by evoked potentials, benefits of auditory training and noise reduction, and the relationship between cognition and speech perception. Recent studies showed noise reduction improved speech scores and dual task performance depended on working memory ability. The research aims to better understand variable outcomes and rehabilitation factors for adult cochlear implant users.

1. Breaking the Sounds of Silence
Adult Cochlear Implant Forum
11 March 2017
Cochlear Implant Research in New Zealand
(45 minutes): 1.45-2.30 pm, 2.45-3.30 pm, 3.45-4.30 pm
Suzanne C Purdy
Speech Science
School of Psychology

2. Captioning
Workshop: NZ Research (SP) Suzanne Purdy
Room 731.203 (LC)
http://captioningstudio.com/live/?bookingref=GXMG5DZP482
03&fs=40
bookingref=GXMG5DZP48203
Live stream: https://auckland.zoom.us/j/828466835

3. • Improvements in speech perception over time are well
documented for cochlear implant users
• Most improvement occurs within a short time after cochlear
implantation in adults
• Some studies show a plateau in performance after several
years
• Auditory evoked potentials (brain responses to sound) are of
interest as they provide an objective measure of auditory
brain change
• Some evoked potential measures, especially cortical evoked
potentials, correlate with performance
Background
3

4. Topics
1. Auditory evoked potentials
2. Auditory plasticity and training
3. Cognition and speech in noise in people with cochlear implants
4. Processing of speech emotion (‘prosody’)
(5 published New Zealand studies)

5. Recording brain
responses to
sound: cortical
auditory evoked
responses
5
http://www.the-
scientist.com/?articles.view/articleNo/43843/title/
The-Sounds-of-Silence/

6. Recording auditory evoked potentials
http://images.slideplayer.com/11/3189898/slides/slide_3.jpg

7. 1. Electrophysiological and
speech perception measures of
auditory processing in
experienced adult cochlear
implant users
AS Kelly, SC Purdy, PR Thorne (2005).
Clin Neurophys 116:1235-46.
250 Hz
4 kHz
Black = control group
Red = ‘better’ CI: sentence scores >85%
Blue = ‘poorer’ CI: sentence scores <40%
• Age range 27–74 years
• CI use 1.3-5.2 years
• Nucleus CI–22M
• Evoked potentials recorded to
tones delivered via
loudspeaker
P1
N1
P2
P1
N1
P2

8. 2. Speech scores improve over time
0
20
40
60
80
100
Visit (months)
Speech
score
(%)
sentences
phonemes
words
0 1 3 6 9
Seminars in Hearing Volume 37 (1) · February 2016
CI24 implant users

9. Evoked potentials improve over time, but with
differing time course: 57 year old with congenital
hearing loss, profoundly deaf for 10 years. P1 changed
very little, N1 reached stable amplitudes at 1 month,
P2 increased in amplitude over the 9 months.
Switch on
1 month
3 months
6 months
9 months
P1
N1
P2

10. Improvements in P2 area over the five visits
• no change for most electrode locations over first 6 months
• 8 of the 10 people had right ear implants
• steady P2 increase over time for C4 (right hemisphere recording)
https://www.sunshinecoastdaily.co
m.au/news/dad-gets-cochlear-
implant-tattoos-support-his-
kids/2991160/

11. 11
http://aja.pubs.asha.org/article.aspx?articleid=2573094
3.

12. Auditory training is a way to
reduce variability in CI outcomes
– Sound and Beyond (Cochlear)
– Hearing for Life (Advanced Bionics)
– only a few independent studies have trialed these programs
independently from the developers (Fu et al., 2007 & Stacey
et al., 2010)

13. Speech in noise scores [and spectral (pitch) discrimination] improved after training
13
0
10
20
30
40
50
60
70
80
v1 v2 v3 v4
Easy Noise Hard Noise
*

14. 14
N1-P2 amplitude significantly larger post-training for /baba/ stimulus in quiet
Pre training Post training
P1
N1
P2
P1
N1
P2

15. 4. Impact of cognition and noise reduction on speech
perception in adults with unilateral cochlear implants
Investigators: Suzanne Purdy¹, David Welch2, Ellen
Giles², Catherine Morgan3, Renique Tenhagen¹, Abin
Kuruvilla-Mathew¹
¹Speech Science, Faculty of Science, University of Auckland
²Audiology, Faculty of Medical & Health Sciences, University of Auckland
3Cochlear Ltd, Sydney, Australia
in press, Cochlear Implants International

16. What is cognition?
cog·ni·tion
/kägˈniSHən/
Noun
1.The mental action or process of acquiring knowledge and
understanding through thought, experience, and the
senses.
2. A result of this; a perception, sensation, or intuition.
Synonyms
knowledge – cognizance – acquaintance
http://www.mcgill.ca/cogsci/

17. Cognitive processes
• Executive function (“involved in complex cognitions, such as
solving novel problems, modifying behaviour in the light of
new information, generating strategies or sequencing
complex actions” Elliot 2003 p.50)
• Memory
• Attention
Reference: R. Elliot. Executive functions & their disorders.
British Medical Bulletin 2003;65:49–59)

18. Listening to speech in noise [effortful
listening] depends on hearing and cognition
http://www.brainvolts.northwestern.edu/projects/speech/speechinnoise/index.php

19. http://thebrain.mcgill.ca/fl
ash/a/a_07/a_07_p/a_07_
p_tra/a_07_p_tra.html

20. Links between cognition and speech
perception with hearing aids
• Thomas Lunner (2003) Cognitive function in relation to hearing aid
use. International Journal of Audiology, 42:sup1, 49-58.
• Thomas Lunner, Mary Rudner, Jerker Rönnberg (2009). Cognition
and hearing aids. Scandinavian Journal of Psychology, 50, 395–403
• Reading span task – process & retain information
simultaneously
• Working memory capacity measured by the reading
span test influenced speech recognition thresholds
in 72 new hearing aid users (40% of variance)

21. Reading span correlated with speech
perception in noise in new hearing aid users
Participants listen to sequences of letters that need to be
recalled at the end
Each letter in the sequence is preceded by an auditory semantic
categorization test – sentence makes sense? yes or no?
Letter recall is tested by asking participants to select letters
they have already seen from a provided letter matrix
http://www.millisecond.com/download/library/v5/L
isteningSpan/AutomatedLSPAN.manual

22. Processing sentences
• The host greeted all the guests and asked them to sit at the
{table | sky}.
• John never liked {crowds | chocolate} and that is why he now
lives in the country.
http://www.pitt.edu/~tol7/res/research/psych-tests/rspan/

23. Questions
1. Does SmartSound iQ (SNR-NR) noise reduction algorithm
improve speech perception and decrease listening effort for
CI recipients listening to speech in noise?
2. What is the ability of people with poorer or better
cognitive ability to benefit from the noise reduction?

24. 35
40
45
50
55
60
off on
HINT
word
score
(%)
Noise reduction
p=0.038
Significant improvement in fixed SNR word score with SNR-NR
on, independent of cognitive ability & age (N=13)
7% average
Improvement

25. Dual task
• Primary listening task
(repeat sentences in noise)
• Secondary visual task
– correct identification of a
number in a visual stream of
numbers
– speed & accuracy measured
Signal+Noise

26. Cognitive ability measured using Weschler Adult
Intelligence Scale Fourth Edition (WAIS-IV Wechsler, 2008)
• Auditory digit span: forwards, backwards,
sequencing (working memory), for example
– Forward: 7 5 6 2 5 3 = 7 5 6 2 5 3
– Backward: 7 5 6 2 5 3 = 3 5 2 6 5 7
– Sequence: 7 5 6 2 5 3 = 2 3 5 5 6 7
• Coding: total number of correct symbols in timed
period (processing speed)

27. Good vs. poor working memory
• Trend for scores to be better
with noise reduction ON for
those with better with working
memory during dual task
• No difference in speech scores
with noise reduction ON vs.
OFF for those with poorer
working memory

28. Recognising
emotion in
speech (happy,
sad, fearful,
angry)
5.
International Journal of Audiology 54(7), 444-452, 2015

29. Key points
• Speech perception with a CI varies but improves with
experience and with training
• Brain responses to sound reflect auditory deprivation and can
change over time with a CI (brain ‘plasticity’)
• Some brain responses correlate with performance but this
differs across studies
• Improved auditory attention and/or pitch perception could
mediate improved P2 evoked responses
• Working memory may influence speech perception scores and
interact with CI processing (further research underway)
• Perception of emotion in speech may be challenging – this
could add to listening effort

30. Cognitive load Questions?
http://www.fitwise.co.uk/files/9314/6356/5133/Pr
amudi_Wijayasiri.pdf

31. Acknowledgements
• CI participants
• Deafness Research Foundation
• Cochlear Ltd
• Pindrop Foundation
Questions? Email me at sc.purdy@auckland.ac.nz

32. Abstract
New Zealand hearing researchers have been investigating outcomes and
rehabilitation for adults using cochlear implants since the 1990s. This presentation
will talk about findings of some of this research, including variable speech
perception outcomes for adults and factors contributing to this. Changes in the
auditory brain have been shown using auditory evoked potentials (electrical activity
from the brain in response to sound that can be measured with sensors on the
scalp). Brain changes occur within a short time after an adult receives a cochlear
implant and continue over an extended period. Recent research has shown that
adults who have used their implants for a long time can still benefit from auditory
training and noise reduction in the cochlear implant improves speech outcomes but
this may depend on cognitive factors such as memory.