Module 11 Flashcards
Regardless of the technology, features, accessories, or forms, hearing aids must achieve ___ and ___
Audibility, comfort
Before the inception of digital devices, how was target gain calculated at each frequency?
-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
What is loudness normalization?
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
What is loudness equalization?
Gain prescribed = gain needed to amplify all speech frequency bands to perceive equal loudness
What prescriptive formula is preferred for adults?
NAL-NL2
T/F: NAL-NL2 is a loudness equalization strategy
TRUE
What prescriptive formula is preferred for paediatrics?
DSL v5
T/F: DSL v5 is a loudness normalization strategy
TRUE
What is the 1/2 gain rule and when was it used?
-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
What is prescription of gain and output (POGO) and when was it used?
-Frequency specific gain calculation
-No consideration of speech spectrum and may not be suitable for severe to profound hearing losses
-1980s
What is the Berger method and when was it used?
-Speech spectrum now considered in prescription
-Variable gain at different frequencies with an emphasis on those important for speech discrimination
-1980s
National Acoustic Labs (NAL) began by treating ___ and ___ in 1947
Service war vets, children
What revisions were made to NAL and when?
-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
What is the central institute for the deaf method (CID) and when was it used?
-Speech spectrum introduced with frequency-specific, measured patient MCLs
-Amplify average speech spectrum to the MCL from frequencies between 500-4000 Hz
-1980s
What is the desired sensation levels (DSL-v5) method and when was it created?
-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
What is the NAL-NL2 method and when was the latest version released?
-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
Why are age and etiology of hearing loss considered in DSL-v5? How much reduction in dB is applied to adults?
-Higher listening level for paediatric (presumed congenital) than for adults (assumed acquired)
-A reduction of ~7 dB is applied for adults
DSL-v5: The compression threshold is ___ for milder losses and ___ for more severe losses
Lower, higher
DSL-v5: Bilateral fittings reduce speech targets by ___ dB
3
List the differences between NAL-NL2 and DSL
-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
T/F: Compared to NAL-NL2, DSL-v5 has better speech intelligibility in quiet but not BGN
FALSE: they have similar speech intelligibility in quiet and BGN and overall loudness is similar
