• Spectral coding and multichannel strategies became central to conveying spectral information in prosthetic hearing, demonstrated by two-formant processing, formant discrimination, two-electrode stimulation, and perceptual findings from Vienna prostheses [2], [8], [16], [13], [7].

• Hardware design and insertion safety drove electrode geometry optimization, with banded intracochlear arrays tested for insertion trauma, alongside pathology studies showing tissue responses to chronically implanted scala tympani electrodes [9], [4], [17], [20].

• Clinical efficacy and outcome variability were documented across multiple designs and patient groups, informing predictors of performance, pediatric versus adult outcomes, and the limits of word and vowel recognition with early implants [12], [11], [10], [14], [19].

• Longitudinal biology of implants highlighted nerve survival and histopathology under chronic stimulation, signaling safety margins and design constraints for durable prostheses [3], [17], [20].

• International symposia and cross-lab reports facilitated rapid knowledge transfer and design iteration, embedding cochlear prostheses in a collaborative research ecosystem [5], [13], [6].