Fitting Formulas

Question 1

What falls under prescribing fitting formulas?

Answer 1

1. Gain/Output Based
2. CT or CR
3. MPO

Question 2

What are the starting points you should consider to find the best fit for your pt?

Answer 2

1. Speech Intelligibility
2. Sound quality
3. Listening comfort

Question 3

What does Non-Linear fitting formulas consist of?

Answer 3

1. Compression
2. Multiple Inputs
3. Multiple Channels

Question 4

What is loudness normalization?

Answer 4

Across all frequencies, overall loudness of sounds being normalized. Sounds that are soft or loud would be amplified for a HL person

Question 5

What is loudness equalization

Answer 5

All frequency bands of speech are amplified to contribute equally to loudness of speech.

Question 6

What is the goal of DSL v5.0?

Answer 6

Provide maximum audibility while maintaining comfortable loudness across all inputs

Question 7

List characteristics for DSL v5.0

Answer 7

1. Specific to WDRC devices
2. Suitable for children
3. Threshold based
4. Age based
5. Convenient

Question 8

List Age & Etiology characteristics for DSL v5.0

Answer 8

1. Adult/Acquired v Pediatric/Congenital
2. Children prefer greater gain because they’re learning language
   - 7dB for moderate
   - 3 dB for severe

Question 9

List type of HL characteristics for DSL v5.0

Answer 9

1. CHL or MHL, give increased gain
2. Will be more linear
3. Raises predicted limit of comfort by 25% of average ABG
4. Dependent on size of ABG
   - Maximal CHL –> 9dB for mild losses, up to 5dB for severe losses

Question 10

What is the goal of NAL-NL2?

Answer 10

Maximize predicted speech intelligibility while making overall loudness sound normal

Question 11

NAL-NL2 has

Answer 11

1. Higher CR

2. Optimize gain at low levels to avoid slightly higher CR

Question 12

What is the goal with verification?

Answer 12

Maximize speech understanding

Question 13

What is the goal of loudness normalization?

Answer 13

Relative loudness of different frequency components of complex sounds will be preserved

Question 14

What is the problem with Loudness Normalization?

Answer 14

Not all speech frequencies carry the same importance

Question 15

What is the goal of loudness equalization?

Answer 15

1. It increases the potential for understanding that once HA is set to user level.
2. Audibility would be maximized if all freq bands of speech contributed equally to loudness perception.

Question 16

For NAL-NL2, what is gender preference for gain?

Answer 16

Male: Prefer more
Female: Prefer less volume ~2dB

Question 17

For NAL-NL2, what is gain preference for user preference?

Answer 17

New User: Slighty less

Experienced: Slightly more

Question 18

For NAL-NL2 & DSL v5.0, when would you prescribe less gain?

Answer 18

For binaural fittings, since they’re wearing 2 HAs

Question 19

For NAL-NL2 what is gain preference for pediatrics?

Answer 19

1. Provide greater amount of gain to them than adults
   - 5dB @ mid inputs
   - More @ low “ “
   - Less @ high

Question 20

On the Verifit, does the following impact REAR targest? 
Gender
Experience
CT
Compression Channels
Compression Speed
EM tubing type
Vent size

Answer 20

No

Question 21

a. Non-Linear fitting formulas consist of?

b. List the fitting formula under each that’s important for us.

Answer 21

a. Normalization & Equalization
b. Normalization: DSL v5.0

Equalization: NAL-NL2

Question 22

What does non-linear fitting formulas focus on?

Answer 22

1. Acclimatization
2. Preferred Loudness/Gain
3. Degree of HL
4. CT

Question 23

What is the goal of non-linear fitting formulas?

Answer 23

Fit the world of sound into the DR of the individual with hearing impairment

Question 24

What is the goal of linear fitting formulas?

Answer 24

Make speech presented at avg audible level, while keeping loud speech & other noises from becoming uncomfortable.