Finetuning and troubleshooting

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• Fine-tuning and troubleshooting
• non-linear hearing aids

ASA Melbourne, 2001
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Non-linear Hearing Aids

• Module 8
• Fine-tuning and troubleshooting
• non-linear hearing aids

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Troubleshooting Outline

• Own voice quality
• Whistling
• Tone quality rating and adjustment
• The trouble-shooting two-step
• Tonal quality
• Too noisy
• Excessive loudness
• Clarity in noise

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Own voice quality

• My voice sounds like it is
• hollow, boomy, echoes, like speaking in a barrel,
  like having a cold, feeling plugged
• How do other peoples voices sound?
• Also bad - fix first!
• O.K. - suspect occlusion

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Occlusion mechanism
Source
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Occlusion mechanism
A
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Occlusion solutions

• Add or enlarge the vent
• Order a long canal stalk

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Occlusion mechanism
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Occlusion mechanism
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Occlusion solutions

• Add or enlarge the vent
• Order a long canal stalk
• Increase or decrease the low frequency gain for
  high level sounds.

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Feedback oscillation
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Feedback solutions

• Build up the earmould or shell
• Use open-jaw impressions
• Decrease the vent size
• Decrease high frequency gain for low level sounds
• Use feedback suppression

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Fine tuning

• Systematic clinical procedures
• quality ratings
• paired comparisons
• Based on field report
• problem confirmed with CD
• solution confirmed with CD

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Fine-tuning of tonal quality Moore, Alcantara
Glasberg (1998)
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Rating scale for overall loudness
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Rating scale for high-level sound quality
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Rating scale for mid-level quality
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Fine-tuning in response to field-report
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The troubleshooting two-step
Step 1 - Decide

• Which direction
• increase gain
• decrease gain
• For which frequencies
• high frequencies
• low frequencies
• For which levels
• low intensities
• medium intensities
• high intensities

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The troubleshooting two-step
Step 2 Deduce

• Which control(s) achieve the desired effects?
• answer depends on the hearing aid

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It sounds shrill, harsh, tinny, hissy, sharp, or
metallic

• Decrease high frequency gain for
• low levels
• medium levels
• high levels
• . (But first check for unwanted peaks)

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Acclimatization

• Time to become accustomed
• No strong evidence that preferences change,
  though plenty of anecdotes
• Listen to strength of complaint
• Compromise reasonable

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It sounds dull, muffled, or unclear

• Increase high frequency gain for
• low levels
• medium levels
• high levels

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It sounds boomy, bassy, or drummy

• Decrease low frequency gain for
• low levels
• medium levels
• high levels

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Its too noisy

• Internal or external?
• Low intensity or high intensity noises?
• Simultaneous or sequential noise?
• Really noise, or wanted signals?
• What, when and where?

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Its noisy in quiet places
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Its too loud in noisy places
High Freq - Crockery - Paper rustling - Water
flushing - Brake squeals
Low Freq - Door slam, - Traffic noise
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Noise makes it hard to understand speech
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Cant understand soft speech
Increase gain for low level sounds
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Troubleshootingtools for step 1

• Your questioning skills
• The real ear gain analyser
• Set of environmental sound CDs

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Step 2 Decide which controls

• Hearing aid dependent
• Know your hearing aids
• Screen displays
• Spec sheets
• Test box measurements

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Two hearing aids
Variation of compression ratio
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Two hearing aids
Variation of compression threshold
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Thats all folks