Advanced Technology Options for Special Fitting Populations

Donald J. Schum, PhDVice President, Audiology & Professional Relations Oticon, Inc

DJS@Oticonusa.com

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

DJS@Oticonusa.com