EEG-based auditory attention decoding with audiovisual speech for hearing-impaired listeners.

Auditory attention decoding (AAD) was used to determine the attended speaker during an auditory selective attention task. However, the auditory factors modulating AAD remained unclear for hearing-impaired (HI) listeners. In this study, scalp electroencephalogram (EEG) was recorded with an auditory selective attention paradigm, in which HI listeners were instructed to attend one of the two simultaneous speech streams with or without congruent visual input (articulation movements), and at a high or low target-to-masker ratio (TMR). Meanwhile, behavioral hearing tests (i.e. audiogram, speech reception threshold, temporal modulation transfer function) were used to assess listeners' individual auditory abilities. The results showed that both visual input and increasing TMR could significantly enhance the cortical tracking of the attended speech and AAD accuracy. Further analysis revealed that the audiovisual (AV) gain in attended speech cortical tracking was significantly correlated with listeners' auditory amplitude modulation (AM) sensitivity, and the TMR gain in attended speech cortical tracking was significantly correlated with listeners' hearing thresholds. Temporal response function analysis revealed that subjects with higher AM sensitivity demonstrated more AV gain over the right occipitotemporal and bilateral frontocentral scalp electrodes.

Surface State Modulation via Electrochemical Heterogeneous Redox Reactions for Full-Color Emission Carbon Dots.

Carbon dots (CDs) still suffer from unclear surface state fluorescence mechanism for fine modulation. Here, redox reactions for cathode and anode within electrochemical method are firstly employed to construct differentiated strategy for surface-state modulation, so as to obtain CDs with controllable emission in separated electrodes simultaneously. The fluorescence peaks of CDs from blue to red centered at 425 nm (mCDs-), 530 nm (mCDs+), 580 nm (oCDs-) and 665 nm (oCDs+) are mainly originated from the different bombardment effects of the ions and reaction tendencies of modifier during the electrolysis process. The phenylenediamine (as modifier) tends to introduce the amino groups on the surface of CDs- while introduced nitrogen atoms into the carbon nucleus skeleton around the anode, thus leading to much larger size and the formation of the graphite N for CDs+. It is the different surface states formed by phenylenediamine and the absorption redshift triggered by graphite N that ensures the tunable emission. The improved electrochemical method is of great significance for finely spectra modulation and efficient synthesis.