1. The expected benefit
of hearing aids as a
function of hearing
loss
Elaine Saunders 1,2, Peter J Blamey 1,3,4
1 Blamey & Saunders Hearing Pty Ltd
2 Faculty of Science & Engineering, Swinburne University of
Technology
3 Dept of Medical Bionics and Dept of Audiology and Speech
Pathology, The University of Melbourne
4 The Bionics Institute

2. Research evidence shows that people who start
with higher expectations achieve better outcomes
with hearing aids
“Higher use time … [and] greater benefit in easy and difficult listening
situations … was predicted by higher pre-fitting expectations.”
Jerram & Purdy, JAAA, 2001
“The data also show that positive expectations result in more positive
outcome …”
Saunders, Lewis, & Forsline, JAAA, 2009
There is an alternative view amongst clinicians that:
“… excessively high expectations will result in disappointment and thus
poor outcome.”
Saunders, Lewis, & Forsline, JAAA, 2009

3. These two views can be reconciled if we can define
“realistic expectations.”
It is desirable that people have positive but not
unrealistic expectations of the benefit of hearing
aids.
So what is a realistic expectation,
……. does it depend on the degree of hearing loss?

4. In a previous study using the Profile of Hearing Aid
Performance* questionnaire, we showed that percentage
of problems for communication in quiet decreased by
0.79% per dB of hearing loss.
Blamey, Martin, & Saunders, SST 2010
* Cox & Alexander, 1995

5. In the current study, we evaluated hearing aid
performance and benefit in quiet as a function of
hearing loss using a speech perception test (SPT).
• Data were collected for 492 people in the Blamey Saunders East
Melbourne clinic
• A 50-word monosyllabic word test1 was performed in aided and
unaided conditions with 65 dB SPL presentation level
• The hearing aids all used the ADRO® amplification scheme2 and
were fitted with Blamey Saunders IHearYou® software
ADRO® is a Registered Trademark of Cirrus Logic
IHearYou® is a Registered Trademark of Blamey Saunders hears
1 Blamey, Blamey, & Saunders. " Journal of telemedicine and telecare 21.8 (2015): 474-478
2 Martin, L., et al. Acoustics Australia 29.1 (2001): 21-24.

6. Example of Speech Perception Test results
(the Infogram™)
Infogram™ is a Trademark of BlameySaunders hears

7. Before hearing aid fitting, the SPT was carried out
(unaided condition).
A typical sigmoid curve fitted the data well, with
50% point at 35.9 dB HL and width of 11 dB.
80706050403020100
50
40
30
20
10
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4-frequency PTA in dB HL
UnaidedSPTscore
Unaided SPT score vs PTA
50%

8. After hearing aid fitting, the SPT was carried out in
the aided condition.
A typical sigmoid curve fitted the data well, with
50% point at 53.4 dB HL and width of 18 dB.
80706050403020100
50
40
30
20
10
0
4-frequency PTA in dB HL
AidedSPTscore
Aided SPT score vs PTA

9. Maximum average benefit on the SPT was 16.8
words (33.6%) at 52 dB HL.
The benefit increased by 0.72% per dB of hearing
loss.
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40
30
20
10
0
-10
4-frequency PTA in dB HL
Benefit=Aided-UnaidedSPTscore
Benefit vs PTA
52 dB HL
16.8 words

10. On average, people made about half as many
errors in the aided conditions as they did in the
unaided condition.

11. Conclusions based on word test results
• The results in this study showed 0.72% per dB
improvement in SPT score, consistent with 0.79% per dB
reduction in problems on the PHAP in an earlier study.
• Hearing aid benefits in quiet increase with hearing loss up
to a PTA of 52 dB HL and then reduce gradually.
• On average, hearing aids produce an improvement in SPT
scores equivalent to a 17.5 dB improvement in hearing
thresholds.
• There is a lot of variability between people, possibly due to
factors other than degree of hearing loss.

12. People are often surprised at how many mistakes
they make on the word test. To estimate how people
would score on sentences, we transformed the data
using the graph below.
Grant, K.W., and Seitz,
P.F. (1997)

13. A typical sigmoid curve fitted the estimated unaided
sentence data well, with 50% point at 48.7 dB HL
and width of 8.5 dB.

14. A typical sigmoid curve fitted the estimated aided
sentence data well, with 50% point at 76.5 dB HL
and width of 15.3 dB.

15. Maximum average estimated benefit for sentences
was 55% at 64 dB HL. Up to 60 dB HL, benefit
increased by 0.72% per dB of hearing loss.
64 dB HL
55% benefit

16. On average, people made about one quarter as
many errors for estimated sentences in the aided
condition as they did in the unaided condition.

17. Conclusions based on estimated sentence scores
 Sentence scores are much less sensitive to hearing loss than word
scores
 Estimated hearing aid benefits for sentences in quiet increase with
hearing loss up to a PTA of 64 dB HL and then reduce gradually.
 On average, hearing aids produce an improvement in estimated
sentence scores equivalent to a 27.8 dB improvement in hearing
thresholds.
 There is a lot of variability between people, possibly due to factors
other than degree of hearing loss.

18. Realistic expectations depend on hearing loss
Realistically, people should expect that hearing aids will:
 Halve the number of errors they make on difficult listening tasks in
quiet (such as monosyllabic word perception)
 Reduce the number of errors they make in running speech (such
as sentences) to one quarter of their current rate
 Allow a person with a mild hearing loss to perform like a person
with normal hearing
 Allow a person with moderate hearing loss to perform like a person
with mild hearing loss
 Allow a person with severe hearing loss to perform like a person
with moderate hearing loss.