Evaluating Hearing Loss for Individuals with Cochlear Implants (2021) / Chapter Skim
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2 Considerations for Evaluating Hearing Function
2 Considerations for Evaluating Hearing Function
Pages 29-48
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From page 29... ...
An audiogram represents detection-based processes in such a way that audiometric thresholds represent the lowest level at which an individual can reliably detect tonal stimuli across the frequency range most important for speech recognition. Perception is a higher-order sensory process that requires that the detected stimulus be transmitted to the central auditory system.
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From page 30... ...
. Individuals with severe-to-profound sensorineural hearing loss -- particularly those using cochlear implants -- report that speech recognition is much more difficult in the presence of background noise (e.g., Donaldson et al., 2009)
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From page 31... ...
. However, for individuals with cochlear implants, a similar assessment cannot be completed because cochlear implant recipients hear through their implanted device transmitted via an externally worn sound processor.
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sentences (Nilsson et al., 1994) -- that assesses speech recognition in a quiet background with sentences presented in the sound field1 via a loudspeaker placed at 0o azimuth (i.e., directly in front of the listener)
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However, because sound field calibration uses a free-field microphone attached to a sound level meter and sound level meters are not equipped with a dB HL reference, presentation levels for speech recognition testing obtained in a sound field are characterized in dB SPL. As such, a presentation level recommendation referencing dB HL for sound field assessment is not possible and would therefore be inappropriate.
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From page 34... ...
The next best option would be daily calibration, because sound field assessment of speech recognition performance without prior calibration might result in an inaccurate description of a listener's auditory performance at the desired presentation level. Furthermore, without calibration the tester could potentially under- or over-estimate speech recognition for patients as the tester could be presenting at a much lower or higher presentation level than intended.
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From page 35... ...
More important than the specific app itself is that the clinician tests the accuracy of the SLM app using the smartphone-integrated microphone against the calibrated SLM with a free-field microphone. Speech Recognition in Quiet Versus Noise Improvements in cochlear implant technology and the expansion of adult implant indications have produced increasing levels of speech recognition in quiet, to the point that unilateral cochlear implant recipients with post-lingual onset of deafness are routinely achieving 60 percent open-set5 word recognition, on average (e.g., Buchman et al., 2020; Holden et al., 2013)
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From page 36... ...
. Hearing Configuration: Unilateral and Bilateral Cochlear Implants A number of studies have compared bilateral and unilateral cochlear implant recipients using open-set sentence tests including the BamfordKowal-Bench Speech-in-Noise Test (BKB-SIN)
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From page 37... ...
Skinner and colleagues first discussed the importance of sound field audiometric thresholds in the range of 20–30 dB HL for determining the minimum audibility available for implant recipients (Skinner et al., 1997, 1999) , and there are now a number of published papers demonstrating that aided thresholds in the range of 20–25 dB HL are associated with significantly higher speech recognition outcomes for adult and pediatric cochlear implant recipients (e.g., Davidson et al., 2009; de Graaff et al., 2020; Holden et al., 2013, 2019)
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From page 38... ...
Note that each implanted ear should be verified independently to verify appropriate programming for each ear. Also, unilateral cochlear implant recipients who have some acoustic hearing in the non-implanted ear should have that ear occluded via foam plug or by a completely occluding earmold so that the implant ear is isolated for sound field testing.
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From page 39... ...
Scoring Speech-in-Noise Tests Clinical speech-in-noise tests are commonly scored using one of two methods. The most common scoring method for cochlear implant recipients is "percent correct based," reporting the percentage of words repeated correctly across a list of sentences presented at a fixed SNR, such as +5 dB SNR.
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LNT Children Monosyllabic Percent correct Kirk et al., 1995 (Lexical words presented Neighborhood at fixed level Test) CNC Adult Monosyllabic Percent correct Causey et al., (Consonant– word lists 1984 Nucleus– presented at fixed Consonant)
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From page 41... ...
10-talker babble at a fixed SNR Pediatric Children Sentences Percent correct Spahr et al., 2014 AzBio presented in 10-talker babble at a fixed SNR CID Sentences Adults Sentences Percent correct Silverman and (Central presented at a Hirsh, 1955 Institute for fixed level, in the Deaf) quiet or noise CUNY Sentences Percent correct Boothroyd et al., Sentences presented at a 1985 (City fixed level, in University of quiet or noise New York)
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From page 42... ...
. Sentence Tests and Word Tests SSA currently uses HINT sentences presented in a quiet background to assess hearing in individuals with cochlear implants at the Listing of Impairments (the Listings)
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. A second concern with the use of speech tests is the method of scoring sentence recognition performance, although most contemporary sentence tests assess accuracy based on the recognition of keywords.
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2020. Unilateral cochlear implants for severe, profound, or moderate sloping to profound bi lateral sensorineural hearing loss a systematic review and consensus statements.
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2011. Speech perception and sound localization by adults with bilateral cochlear implants.
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Cochlear Implants International 11(2)
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2016. Method of speech stimulus presentation impacts pediatric speech recognition monitored live voice versus recorded speech.
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