%0 Journal Article
%T The Growth of Loudness in Cochlear Implant Listeners; Possible Developmental Effects?
%A Nicole M Anzalone
%A Robert L Smith
%J International Journal of Otolaryngology | Open Access Journal | Head & Neck Surgery
%D 2017
%X There have been limited psychophysical measurements on growth of loudness in early-deafened cochlear implant users as compared to postlingually-deafened cochlear implants users. In this study, the ¡°shape¡± of the loudness growth function was investigated for prelingually- and postlingually-deafened subjects by measuring loudness growth within the electrical dynamic range on different bipolar electrode pairs using Absolute Magnitude Estimation (AME) and Absolute Magnitude Production (AMP). The shapes of the loudness functions were obtained and verified by comparing loudness growth models using the Akaike¡¯s Information Criterion (AIC) method to obtain the best- fit functions. Results suggest that adult cochlear implant listeners can exhibit different loudness growth functions, depending on their acoustical experience prior to implantation. Eight subjects with considerable acoustic experience prior to implantation and relatively late implantation demonstrated loudness functions that grew according to an expansive nonlinearity, in agreement with results from several previous studies. In contrast, the four early-deafened subjects with little or no useful acoustic experience prior to implantation, had loudness functions that grew in proportion to stimulus current amplitude. These results suggest that the shape of the loudness function is molded in part by the nature and functionality of input to the central auditory system during auditory development
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