Advanced Technology Options for Special Fitting Populations
Donald J. Schum, PhDVice President, Audiology & Professional Relations Oticon, Inc
Schum & Collins, 1992
Schum & Collins, 1992
How do we describe a patient’s auditory status?
• By the audiogram
• By the physiological condition of the ear
Yost & Nielsen, 1985
aaarrrrr!
Lok, 2005
• “Hearing Loss Correction”
– compensation for threshold loss
– gain provided proportional to HTL
Models of Intervention
• “Hearing Loss Correction”
– compensation for threshold loss
– gain provided proportional to HTL
• “Residual Capabilities”
– aided signal viewed in relation to remaining
auditory abilities
Models of Intervention
Ski Slope Hearing Loss
• Beyond moderate SNHL in HF, improved audibility may not
always improve speech understanding
• At times, attempts at full audibility may decrease speech
understanding
Key Research Findings
Skinner (1980)
250 500 1000 2000 4000 8000
Hertz
100
80
60
dB
SPL
40
20
0
UCL
HTL
SUBJECT 5
Skinner (1980)
250 500 1000 2000 4000 8000
Hertz
100
80
60
dB
SPL
40
20
0
UCL
HTL
54%Aided Speech Spectra
SUBJECT 5
Skinner (1980)
250 500 1000 2000 4000 8000
Hertz
100
80
60
dB
SPL
40
20
0
UCL
HTL
54%
66%
70%
Aided Speech Spectra
SUBJECT 5
• Beyond moderate SNHL in HF, improved audibility may not
always improve speech understanding
• At times, attempts at full audibility may decrease speech
understanding
• . . .but!!
Key Research Findings
• Who is the patient?
Goals of Ski Fitting
• Who is the patient?
• Maintain comfort
• Maintain acceptable sound quality in quiet
– no dramatic frequency responses
– vented fitting
• Modest audibility enhancement
– focused on transition region
– will be appreciated in quiet
– may be quite helpful in noise
Goals of Ski Fitting
Frequency250 500 1000 2000 4000 8000
dB
HL
Frequency250 500 1000 2000 4000 8000
dB
HL
Voicing & Suprasegmentals
Vowels: F1
Glides
Nasality
F2 Transitions
Vowels: F2
Vowels: F3
Plosive Bursts
Affricate Bursts
Fricatives
Liquids
Re
lati
ve I
mp
ort
ance
200 500 1000 2000 3000 5000
SpeechImportance
Function
Voicing & Suprasegmentals
Vowels: F1
Glides
Nasality
F2 Transitions
Vowels: F2
Vowels: F3
Plosive Bursts
Affricate Bursts
Fricatives
Liquids
Re
lati
ve I
mp
ort
ance
200 500 1000 2000 3000 5000
SpeechImportance
Function
Reverse Slope Hearing Loss
• Typically congenital. . .not talking about Meniere’s related
hearing loss
• Often difficult to fit
• What do they want to hear . . .
• . . . And what are they going to use to hear it
Voicing & Suprasegmentals
Vowels: F1
Glides
Nasality
F2 Transitions
Vowels: F2
Vowels: F3
Plosive Bursts
Affricate Bursts
Fricatives
Liquids
Re
lati
ve I
mp
ort
ance
200 500 1000 2000 3000 5000
SpeechImportance
Function
Schum & Collins, 1992
Schum & Collins, 1992
AverageIntelligibility
Ratings
Schum & Collins, 1992
High FrequencyConsonant
DiscriminationScores
Schum & Collins, 1992
0
20
40
60
80
100
120
< < <dB HL
Frequency (Hz.)
How should the frequency response be set?
• HF region (>2 kHz): at least 10-15 dB Insertion Gain
• LF & Mids Region (<2 kHz): no more than 15-20 dB Insertion Gain
30
20
I.G. 10
0
-10
Fine Tuning?
.25 .5 1 2 4 8
Freq. (kHz.)
• HF region (>2 kHz): at least 10-15 dB Insertion Gain
• LF & Mids Region (<2 kHz): no more than 15-20 dB Insertion Gain
30
20
I.G. 10
0
-10
Fine Tuning?
.25 .5 1 2 4 8
Freq. (kHz.)
Irregular Hearing Loss
NAL NL-1 DSL i/o
Inse
rtio
n G
ain
Inse
rtio
n G
ain
NAL-NL1 Modification
Prescribed Adjusted
Medically Complex Hearing Loss
• Meniere’s
• Sudden sensorineural hearing loss
• Eight nerve tumors/disorders
• Central neurological disorders
• Idiopathic
• More than OHC/IHC problems
• Word recognition usually significantly reduced, even in quiet
• Often:
– severely restricted dynamic range
– Instability
– Severe distortion
– Asymmetries
AIDED RESULTS
Quiet +10 S/N
Left Only 76% 56%
Binaural 92% 88%
Don’t say no until you know . . .
Role of WDRC. . .
Fitting Strategies Study
• Comparison of linear & non-linear strategies
• 15 subjects, various Medically Complex etiologies
• Field trial use of nine different H.A.s:
– linear & nonlinear
• Objective & Subjective evaluations
Multi-channel, nonlinear
Perhaps less gain & more compression . . .
Managing Asymmetries . . .
Success criteria . . .
Severe & Profound Hearing Loss
Congenital
Viral
Meningitis
Ototoxicity
Sudden or Idiopathic
• Inter-patient variability goes up for greater hearing losses
– The greater the damage, the more variable the damage
– Not just Outer Hair Cell loss, but:
• Inner Hair Cell loss (including “Dead Zones”)
• Membrane disruptions
• Neural cell death
• Mechanical & metabolic disruptions
• Disrupted coordination
Why do we use compression?
Speech Intelligibility?
De Gennaro, Braida,
& Durlach, 1986
De Gennaro, Braida,
& Durlach, 1986
52%
56%
59%
58%
Maximum speech discrimination as a function of average hearing loss.
Lamore, Verweij & Brocaar, 1990
• Good chance to appreciate MCNL advantages
– . . .if there is hearing above 1 kHz.
– . . .must be “power MCNL” approach
• Feedback cancellation may expand fitting range
• If they seem to be looking for more linear approach:
– Probably need a shift to a more LF response
– flexibility will have an important role
• Explore the Dynamic Range
• Watch the Compression Trade-off
• Consider Manual Over-ride” thinking
• Good chance to appreciate MCNL advantages
– . . .if there is hearing above 1 kHz.
– . . .must be “power MCNL” approach
• Feedback cancellation may expand fitting range
• If they seem to be looking for more linear approach:
– Probably need a shift to a more LF response
– flexibility will have an important role
• Explore the Dynamic Range
• Watch the Compression Trade-off
• Consider Manual Over-ride” thinking
• Good chance to appreciate MCNL advantages
– . . .if there is hearing above 1 kHz.
– . . .must be “power MCNL” approach
• Feedback cancellation may expand fitting range
• If they seem to be looking for more linear approach:
– Probably need a shift to a more LF response
– flexibility will have an important role
• Explore the Dynamic Range
• Watch the Compression Trade-off
• Consider Manual Over-ride” thinking
• Good chance to appreciate MCNL advantages
– . . .if there is hearing above 1 kHz.
– . . .must be “power MCNL” approach
• Feedback cancellation may expand fitting range
• If they seem to be looking for more linear approach:
– Probably need a shift to a more LF response
– flexibility will have an important role
• Explore the Dynamic Range
• Watch the Compression Trade-off
• Consider Manual Over-ride” thinking
• Good chance to appreciate MCNL advantages
– . . .if there is hearing above 1 kHz.
– . . .must be “power MCNL” approach
• Feedback cancellation may expand fitting range
• If they seem to be looking for more linear approach:
– Probably need a shift to a more LF response
– flexibility will have an important role
• Explore the Dynamic Range
• Watch the Compression Trade-off
• Consider Manual Over-ride” thinking
• Good chance to appreciate MCNL advantages
– . . .if there is hearing above 1 kHz.
– . . .must be “power MCNL” approach
• Feedback cancellation may expand fitting range
• If they seem to be looking for more linear approach:
– Probably need a shift to a more LF response
– flexibility will have an important role
• Explore the Dynamic Range
• Watch the Compression Trade-off
• Consider “Manual Over-ride” thinking
• “Hearing Loss Correction”
– compensation for threshold loss
– gain provided proportional to HTL
• “Residual Capabilities”
– aided signal viewed in relation to remaining
auditory abilities
Models of Intervention
Advanced Technology Options for Special Fitting Populations
Donald J. Schum, PhDVice President, Audiology & Professional Relations Oticon, Inc