1. Effect of Open fittings
May, 2004
Johnny H. Hansen Director, Global Technical Operations GN ReSound as.

2. What’s the problem?
M&M Hearing Uppsala Sweden – Experienced problems 6 months after fitting – Based on 1361 responses

3. It’s all about occlusion…

4. Occlusion 1k 8k 2k 4k
500
250
Frequency (Hz)
dB SPL in ear canal
CIC with pressure vent
BTE with 1.5 mm vent
Open mold
Sound pressure measured in ear for own vocalization of vowel /ee/

5. …..and feedback

6. The dilemma.. and the solution
Effect of Stabilizer DFS

7. Why ResoundAIR and Canta7/Open are so revolutionary?
Because we have combined:
state-of-art technology in earmould design/venting
signal processing in ComforTech .

8. ComforTech: WarpOpen

9. Stabilizer™ DFS Technology
Feedback
path S
WarpOpen
Compression
system
Static filter bank
Adaptation
Adaptive filter -
The feedback path is measured and stored in the static filter bank which is a “mirror” of the actual acoustic feedback path

10. The proof….

11. Hearing threshold level (dB HL)
The occlusion research project in Giessen Germany… 20 40 60 80
100
120
125 1k
Frequency (Hz)
Hearing threshold level (dB HL)
250
500 2k 4k 8k
AC HTL
BC HTL
NH group (n = 9)
HI group (n = 10)

12. FlexVent and ResoundAIR Ear Tip
(front)
FlexVent
(rear)
ResoundAIR
ear tip

13. Occlusion measure (dB)
Measured occlusion:
SPL increase in ear canal at low frequencies when reading a standard text -5 5 10 15 20
Occlusion measure (dB)
Test
Retest
Flex-
Vent
1.6 mm
Earmold
vent
2.4 mm
ReSound
AIR
ear tip
Un-
occluded
all subjects (n = 19)

14. Experienced occlusion:
NH group (n=9) -2 2 4 6 8 10
Occlusion rating (arb. units)
Flex-
Vent
1.6 mm
Earmold
vent
2.4 mm
ReSound
AIR
ear tip
Un-
occluded
Test
Retest
HI group (n = 10) -2 2 4 6 8 10
Occlusion rating (arb. units)
Flex-
Vent
1.6 mm
Earmold
vent
2.4 mm
ReSound
AIR
ear tip
Un-
occluded
Test
Retest

15. The challenge: Open fitting in custom (CIC) products

16. Stepped vent in CIC device
Here you see an example of how the stepped vent looks like in a CIC device.

17. Feedback path response10 2 3 4
-80
-70
-60
-50
-40
-30
-20
-10
Frequency, Hz
Feedback path response, dB
Stepped
Not stepped
Stepping makes the vent shorter and shifts the peak of the high frequency resonance,
reducing the likelihood
of feedback and
optimizes Stabilizer function.
A vent produces a low frequency peak at the cut off frequency which is evident
on a coupler measurement and is largely damped in a real ear. This resonance
produces gain (insertion gain) and reduces the amount of attenuation for the
frequencies in the region of the peak. That is, the attenuation slope is not a
straight line.
The stepped vent have a significant effect in reducing the risk of feedback in the
high frequencies by shifting the high frequency resonant vent peak up in
frequency - beyond the useful bandwidth of the aid. The effect of the Stabilizer is
thereby increased

18. The Challenge..

19. The Challenge….
Stepping optimize the work conditions for Stabilizer-DFS but don’t create significant occlusion reduction
To obtain full Open comfort benefits in CIC’s we need very large vent diameter combining new skills and mindset challenge with dispenser, the sales force and the Lab
More in the next sessions……….

20. Vents….

21. How do Vents work ? Sound bore Dampers Vents
Vents affect the low frequencies
Vents
Dampers
Sound bore
(Dillon, 2001)

22. What determines the vent effectiveness
Acoustic Mass determines the vent effect
The lower the Acoustic Mass the higher the vent effect (occlusion relief)
Formula
Vent Length x
Constant
Vent diameter2

23. Effects of Ventilation
Low frequency sounds can enter and leave the ear canal through the vent.
Transmission of low frequency sounds is easier the smaller the acoustic mass of the vent.
The acoustic mass of the vent is calculated from the length & diameter of the vent.
Increasing the diameter reduces the acoustic mass
Decreasing the length reduces the acoustic mass

24. Openness of vents
Non-occluding
Non-occluding
Open
Closed
Closed

25. How open are our instruments
ReSoundAir rating 1
FlexV (L) rating 3
FlexV (M) rating 4
Tmold (2.4) rating 6
Tmold (1.6) rating 7
S.CIC (2.3) rating 5
T.CIC (2.3) rating 5
FV(M):4
FV(L):3
Air:1
IROS
SCIC:5
Here you see the subjective occlusion rating (HI subjects) from the Giessen trial.
Explain why the stepped vent doesn’t alleviate occlusion. Venten kortes af, men kun ud til et hulrum som ikke er åbent, idet resten af apparatet fylder en del af øregangen ud.
Vent length in custom products:
19 x 2 (right and left) CIC devices vent length (stepped vent):
average of 1,48 cm
19 x 2 (right and left) CIC devices vent lengh (traditionel vent):
average of 1,99 cm.
Vent length of tradional earmold vents:
6 Earmolds 2,4 mm:average of 1,9 cm (vent length)
6 Earmolds 1,6 mm: average of 1,8 cm (vent length).
TCIC:5
Tmold:7
Tmold:6

26. Sound Demo´s
Speak
Crunching

27. Custom Products

28. Problems in the Lab
Custom products with open fittings, especially CIC’s often cause trouble for the Lab.
To get room for the vent canal you occasionally have to compromise.
You can focus on either Cosmetics or Comfort.
You can compromise on either vent diameter or instrument size.

29. Full cosmetic benefits
Custom Open Products
Vent diameter
Small
Large
Full cosmetic benefits
Small
Select cases*
* Cases of larger ear canals
Instrument size
Full comfort benefits
No perceived benefits
Large
Ø 1.6 mm (~2.0 mm2) Ø 2.6 mm Ø 3.0 mm (~7.0 mm2)
<-Closed
Open ->

30. Vents on Custom Products
Non-occluding
Non-occluding
Open
Custom
Closed
Closed

31. The conscious choice Compromise on instrument size.
Risk of Return due to protrusion
Comfort
Limited room for vent
Cosmetics
Compromise on vent diameter.
Risk of Return due to occlusion.
Keep in mind that 40% of users experience Occlusion as the primary problem

32. Venting Process 1

33. Large vent issues
Faceplate Module Battery Hybrid Receiver

34. Large vent issues
Faceplate Module Battery Hybrid Receiver

35. Large vent issues
Faceplate Module Battery Hybrid Receiver

36. Lab Training America Asia Europe North Europe South
4 Lab training sessions to be co-ordinated with Product/Mkt/Sales training
America
(Bloomington)
March 3rd
US – CND
Asia
(DanaJapan)
March 9th
JPN – CHI – AUS - NZ
Europe North
(Taastrup)
March 9th
GER – HOL – FRA
DEN - SWE – NOR - BRA
Europe South
(Madrid)
March 12th
SPA – ITA – U.K.
BEL - SWI - A

37. Thank you.
Questions ?