DFIICP Audiology

1
(No Transcript)
2
Severe Hearing Loss

• High thresholds and poor speech discrimination
• Neural coding can be incomplete.
• Hearing levels have often been longstanding
• Even aided speech intelligibility can be poor.
• Acoustic feedback problems.

3
Typical Dynamic Ranges
dB HL
0
10
20
Mild
30
40
Moderate
50
60
70
Severe
DR65 dB
80
DR50 dB
90
100
DR40 dB
110
120
4
Normal
IHC OHC
Damaged IHC OHC
5
Aid History and Preferences

• Severely hearing impaired can vary widely in
  their hearing aid histories and preferences.
• Long-term linear users may initially prefer the
  sound of an aid more like what they are familiar
  with.
• A non-linear aid can provide greater audibility
  of soft sounds, automatic operation.

6
Manual Override
7
Automatic Functioning

• Override facility does not require frequent
  attention fully automatic.
• When set as a non-linear device, the aid can
  adjust itself far quicker and more often than a
  user could.
• The wheel can be made inactive if required for
  patients such as young children or patients with
  dexterity problems.

8
I/O Curves

• Graph of ASA2p I/O curve showing effect of v/c
  adjustment.

130
120
110
Output (dB SPL)
100
Manual Override
90
80
70
Input (dB SPL)
9
Hearing Level Fluctuations

• Manual override can also be activated by user at
  times when they have fluctuations in hearing
  thresholds.
• Fluctuating sensorineural pathology
• Menieres Disease
• Ototoxicity due to Quinine or Salicylates
• Fluctuating conductive pathology
• Otitis Media or Eustachian Tube Dysfunction.

10
Compensation Strategy
½-gain rule
HF-soft gain

• Graph of ASA2p soft-gain curve showing effect of
  hearing loss
• Loud gain according to compression ratio as in
  ASA2

60
Full compensation
55
50
Gain (dB)
45
40
70 compensation
35
30
HTL (dB HL)
11
I/O Curves, ASA2p (HTLgt75)
LF
HF
MPO according to UCL
MPO according to UCL
CRlt 41
CRlt 31
Output (dB SPL)
Input (dB SPL)
Input (dB SPL)
12
Compression Kneepoint

• Increasing kneepoint can
• Make response more linear (not the only way)
• Reduce gain for low level sounds

13
Compression Kneepoint
LF HF

• Increasing kneepoint can
• Make response more linear (not the only way)
• Reduce gain for low level sounds

MPO according to UCL
Input (dB SPL)
14
ASA2p Fitting range
15
Precise Fitting

• Seven-band with steep filter design
• Precise fitting of traditionally challenging
  audiogram configurations such as the Reverse
  Slope, Flat Slope,Cookie Bite,Mild Slope
  Steep Slope.

16
Feedback Management

• Severely hearing impaired rely totally on their
  hearing aids for speech reception.
• Gain adjustments to control acoustical feedback
  can significantly cut useable gain within this
  very narrow aided range.
• Precise 4-band automatic system.

17
(No Transcript)
18
Take-home Messages

• Fully automatic with manual override.
• ASA2p rationale- Optimised speech
  intelligibility.
• Wide fitting range and flexibility.
• Encouraging clinical results to date.

19
(No Transcript)