Discussion
vowel and word recognition
SEPARATION
This report prospectively evaluated the early speech recognition for EAS users as a function of electric mismatch. Participants listened exclusively with either default maps (median electric mismatch: −5 semitones) or place-based maps that eliminated electric mismatches for low- to mid-frequency information. Poorer speech recognition was observed for EAS users with larger magnitudes of electric mismatch. For example, models including all participants predict poorer performance at 6 months postactivation for individuals listening to maps with 6 semitones of electric mismatch as compared to maps with no electric mismatch by 21 and 22 RAUs for vowel and word recognition, respectively. These data suggest that electric frequency-to-place mismatches may influence the speech recognition outcomes of adult EAS users—at least within the initial 6 months of device use. The preliminary patterns of performance for EAS users with place-based maps suggest the utility of methods that minimize or eliminate electric mismatches to support early speech recognition.The early effects of electric frequency-to-place mismatches for EAS users corroborate the previously observed performance differences for participants with normal hearing listening to EAS simulations. In both paradigms, we observe better performance with place-based maps than for spectrally shifted maps (One factor to consider when evaluating the present place-based mapping procedure is that it may result in a spectral gap between the acoustic and electric outputs. Default mapping procedures limit spectral gaps by assigning a single frequency to the acoustic cutoff and electric low-frequency filter. The poorer performance with spectral gaps for EAS users and listeners for EAS simulations (Another factor to consider is electric-on-acoustic masking. For CI recipients with electrode contacts that reside close to or within the region of functional acoustic hearing, the electric current spread from apical electrode contact(s) may introduce substantial masking of the low-frequency acoustic cues (These preliminary data indicate that electric frequency-to-place mismatches influence the early performance of EAS users, although there are limitations worth consideration. This report estimated the cochlear place frequency using the SG frequency-to-place function described by Another limitation is the modest sample size of the current study, which is not sufficient to assess the relationship between electric mismatches, AID of E1, and other device and mapping variables that have been observed to influence the speech recognition of CI recipients, such as angular separation between the electrode contacts (