Table 1.

Summary of study outcomes investigating the effects of CI fitting parameters for bilateral-aided EAS patients. Studies primarily investigating the effect of HA parameters on EAS benefit were not included here.

Study	Devices	Study details	Findings
Gantz and Turner (2003)	• Nucleus Hybrid S8, 6 mm & 10 mm • Straight electrode • Electrode insertion depth: 6 to 10 mm	• n = 6 (3, 6 mm; 3 10 mm) • HA bandwidth: • LF CI cutoffs: multiple tested, details not provided	• Speech understanding differences were not presented • “most successful maps” had LF CI cutoff of 1000 or 2000 Hz • no difference between 1000 & 2000 Hz
Kiefer et al. (2005)	• MED-EL Combi 40+ standard or medium • Straight electrode • Electrode insertion depth: 19 to 24 mm	• n = 13 • HA bandwidth: • 125 to 1000 Hz (audibility up to 500 Hz for all listeners) • LF CI cutoffs: 300, 650, and 1000 Hz	• 12 of 13 listener preferred 300 Hz • speech understanding not assessed across LF CI cutoff
James et al. (2005)	• Nucleus CI24RCA • Perimodiolar electrode • Electrode insertion depth: 17–19 mm	• CI cutoffs: full spectral bandwidth, 188+ Hz,	• results for the different LF CI cutoffs were not reported
Fraysse et al. (2006)	• Nucleus CI24RCA • Perimodiolar electrode • Electrode insertion depth: 17 mm	• n = 9 • HA bandwidth: 125 up to ≥ 500 Hz (amplify up to audiometric frequency reaching 80 dB HL, range not specified) • 2 CI cutoffs: 1) MAP A = full spectral bandwidth, 188+ Hz, 2) MAP C = higher LF CI cutoff, but not specified	• 7 of 9 listeners preferred MAP C (less EAS overlap) • no difference for speech understanding across the cutoffs • trend for higher sentence recognition in noise with MAP C
Vermeire et al. (2008)	• MED-EL Combi 40+ standard or medium • Straight electrode • Electrode insertion depth: 18 mm	• n = 4 • HA bandwidth: amplifying frequencies with thresholds 1) ≤ 85 dB HL and 2) ≤ 120 dB HL • 2 CI cutoffs: 1) full spectral bandwidth, 200+ Hz, and 2) “falloff” frequency at which audiogram > 65 dB HL (ranging from 250 to 700 Hz)	• higher LF CI cutoff (audiogram falloff) yielded significantly higher speech understanding in noise
Simpson et al. (2009)	• Nucleus CI24RE(CA) • Perimodiolar electrode • Electrode insertion depth: ~18 mm	• n = 5 • HA bandwidth: full audible bandwidth per NAL-NL1 prescriptive fitting formula • 2 CI cutoffs: 1) full spectral bandwidth, 188+ Hz, and 2) acoustic frequency pitch-matched to most apical electrode (ranging from 579 to 887 Hz)	• no difference for speech understanding across the cutoffs
Karsten et al. (2012)	• Nucleus Hybrid S8 & S12 • Straight electrode • Electrode insertion depth: 10 mm	• n = 10 • HA bandwidth: full audible bandwidth per NAL-NL1 prescriptive fitting formula • 3 CI cutoffs: 1) overlap—LF CI cutoff = 50% below upper limit of acoustic audibility (e.g., if audibility upper limit is 1000 Hz, the overlap cutoff = 500 Hz), 2) meet—LF CI cutoff = upper acoustic audibility), and 3) gap—LF CI cutoff = 50% above upper limit of acoustic audibility (i.e. if audibility upper limit is 1000 Hz, the gap cutoff = 1500 Hz)	• “meet” LF CI cutoff yielded significantly higher speech recognition in noise as compared to “overlap” • “meet” and “gap” were not significantly different
Plant and Babic (2016)	• Nucleus Hybrid L24, CI422, CI24RE(CA)/CI512, and modiolar research array (MRA) • Electrode insertion depths: 16 to 20 mm	• n = 16 in total study; n=11 with comparison of overlapping vs. non-overlapping frequency assignment for EAS) • HA bandwidth: full audible bandwidth per NAL-NL1 [for 422, CI24RE(CA) & 512] or NAL-RP (for Hybrid-L24) prescriptive fitting formula • 2 CI cutoffs: 1) overlapping—full spectral bandwidth 188+ Hz, and 2) non-overlapping—ranging from 688 to 1060 Hz—equivalent to the frequency at which audiogram ≤ 80 dB HL or 125-Hz lower (per subjective report of sound quality)	• Speech understanding differences were not presented • 7 participants expressed preference for non-overlapping • 2 expressed preference for overlapping • 2 expressed no preference