Module 11

Question 1

Regardless of the technology, features, accessories, or forms, hearing aids must achieve ___ and ___

Answer 1

Audibility, comfort

Question 2

Before the inception of digital devices, how was target gain calculated at each frequency?

Answer 2

-Using tables for calculation
-Done prior to hearing aid selection
-Today, digital hearing aids have flexible frequency responses and the prescriptive formulas are included within the fitting software and verification equipment

Question 3

What is loudness normalization?

Answer 3

Gain prescribed = gain needed for the person with hearing loss to rate the sound level the same as it would be rated by people with normal hearing

Question 4

What is loudness equalization?

Answer 4

Gain prescribed = gain needed to amplify all speech frequency bands to perceive equal loudness

Question 5

What prescriptive formula is preferred for adults?

Answer 5

NAL-NL2

Question 6

T/F: NAL-NL2 is a loudness equalization strategy

Answer 6

TRUE

Question 7

What prescriptive formula is preferred for paediatrics?

Answer 7

DSL v5

Question 8

T/F: DSL v5 is a loudness normalization strategy

Answer 8

TRUE

Question 9

What is the 1/2 gain rule and when was it used?

Answer 9

-Gain prescribed = hearing threshold X 0.5 for each frequency
-Didn’t consider speech spectrum, and was not suitable for severe to profound loss
-1940s

Question 10

What is prescription of gain and output (POGO) and when was it used?

Answer 10

-Frequency specific gain calculation
-No consideration of speech spectrum and may not be suitable for severe to profound hearing losses
-1980s

Question 11

What is the Berger method and when was it used?

Answer 11

-Speech spectrum now considered in prescription
-Variable gain at different frequencies with an emphasis on those important for speech discrimination
-1980s

Question 12

National Acoustic Labs (NAL) began by treating ___ and ___ in 1947

Answer 12

Service war vets, children

Question 13

What revisions were made to NAL and when?

Answer 13

-NAL-R (revised) and NAL-RP (revised for profound losses):
·LF gain reduction to minimize effects of background noise
·Minimize excessive gain in HF for steeply sloping losses
-1970s

Question 14

What is the central institute for the deaf method (CID) and when was it used?

Answer 14

-Speech spectrum introduced with frequency-specific, measured patient MCLs
-Amplify average speech spectrum to the MCL from frequencies between 500-4000 Hz
-1980s

Question 15

What is the desired sensation levels (DSL-v5) method and when was it created?

Answer 15

-Created in the mid 1980s to provide a systematic, science-based approach to pediatric fittings
-Optimizes speech recognition for children with hearing loss, brings speech to a desired sensation level to maximize intelligibility

Question 16

What is the NAL-NL2 method and when was the latest version released?

Answer 16

-Latest version released in 2011
-Ideal for fitting hearing instruments with WDRC
-Focus on tonal and non-tonal language
-Gender differences: males prescribed more gain than females

Question 17

Why are age and etiology of hearing loss considered in DSL-v5? How much reduction in dB is applied to adults?

Answer 17

-Higher listening level for paediatric (presumed congenital) than for adults (assumed acquired)
-A reduction of ~7 dB is applied for adults

Question 18

DSL-v5: The compression threshold is ___ for milder losses and ___ for more severe losses

Answer 18

Lower, higher

Question 19

DSL-v5: Bilateral fittings reduce speech targets by ___ dB

Answer 19

3

Question 20

List the differences between NAL-NL2 and DSL

Answer 20

-For NAL-NL2, more initial gain for experienced users and less initial gain for new users. NO correction for gain based on experience level in DSL
-NAL-NL2 reduces gain for females than males, while DSL has no adjustments in gain based on gender
-For NAL-NL2, bilateral fittings correct gain changes based on input. In DSL, there is a 3 dB decrease across input levels for bilateral fittings
-NAL-NL2 has no correction factors for listening in noise, while DSL has -3 to -5 dB reduction for “low importance frequencies”
-NAL-NL2 corrects for ABG by considering SNHL first and then 75% of the ABG added on. DSL raises the UCL by 25%
-NAL-NL2 does not take into account patient-specific LDLs, while DSL alters gain if patient-specifics are specified

Question 21

T/F: Compared to NAL-NL2, DSL-v5 has better speech intelligibility in quiet but not BGN

Answer 21

FALSE: they have similar speech intelligibility in quiet and BGN and overall loudness is similar