A subjective evaluation of different music preprocessing approaches in cochlear implant listeners.

Cochlear implants (CIs) can partially restore speech perception to relatively high levels in listeners with moderate to profound hearing loss. However, for most CI listeners, the perception and enjoyment of music remains notably poor. Since a number of technical and physiological restrictions of current implant designs cannot be easily overcome, a number of preprocessing methods for music signals have been proposed recently. They aim to emphasize the leading voice and rhythmic elements and to reduce their spectral complexity. In this study, CI listeners evaluated five remixing approaches in comparison to unprocessed signals. To identify potential explaining factors of CI preference ratings, different signal quality criteria of the processed signals were additionally assessed by normal-hearing listeners. Additional factors were investigated based on instrumental signal-level features. For three preprocessing methods, a significant improvement over the unprocessed reference was found. Especially, two deep neural network-based remix strategies proved to enhance music perception in CI listeners. These strategies provide remixes of the respective harmonic and percussive signal components of the four source stems "vocals," "bass," "drums," and "other accompaniment." Moreover, the results demonstrate that CI listeners prefer an attenuation of sustained components of drum source signals.

Nonauditory Functions in Low-performing Adult Cochlear Implant Users.

INTRODUCTION: Despite substantial benefits of cochlear implantation (CI) there is a high variability in speech recognition, the reasons for which are not fully understood. Especially the group of low-performing CI users is under-researched. Because of limited perceptual quality, top-down mechanisms play an important role in decoding the speech signal transmitted by the CI. Thereby, differences in cognitive functioning and linguistic skills may explain speech outcome in these CI subjects. MATERIAL AND METHODS: Fifteen post-lingually deaf CI recipients with a maximum speech perception of 30% in the Freiburger monosyllabic test (low performer = LP) underwent visually presented neurocognitive and linguistic test batteries assessing attention, memory, inhibition, working memory, lexical access, phonological input as well as automatic naming. Nineteen high performer (HP) with a speech perception of more than 70% were included as a control. Pairwise comparison of the two extreme groups and discrimination analysis were carried out. RESULTS: Significant differences were found between LP and HP in phonological input lexicon and word retrieval (p = 0.0039∗∗). HP were faster in lexical access (p = 0.017∗) and distinguished more reliably between non-existing and existing words (p = 0.0021∗∗). Furthermore, HP outperformed LP in neurocognitive subtests, most prominently in attention (p = 0.003∗∗). LP and HP were primarily discriminated by linguistic performance and to a smaller extent by cognitive functioning (canonic r = 0.68, p = 0.0075). Poor rapid automatic naming of numbers helped to discriminate LP from HP CI users 91.7% of the time. CONCLUSION: Severe phonologically based deficits in fast automatic speech processing contribute significantly to distinguish LP from HP CI users. Cognitive functions might partially help to overcome these difficulties.