Is ageing associated with a decline in peripheral blood CD56bright NK cells?
The number of CD56bright NK cells within peripheral blood declines with age. As this population plays a central role in cytokine secretion during the innate immune response this decline may contribute to impaired immune regulation in elderly individuals.
The amount of amplitude compression does not significantly affect phoneme recognition, whereas reducing dynamic range significantly lowers phoneme recognition, particularly in noise and for vowels. Because the SPEAK processor extracts mostly spectral peaks, the present conclusions may not be applied to other types of processors extracting temporal envelope cues. The present results also suggest that more than four electrodes are required to optimize speech recognition in multiple-talker and noise conditions. A significant performance gap in speech recognition still remains between cochlear implant and normal-hearing listeners at the same signal to noise ratios. Improved cochlear implant designs and fitting procedures are required to narrow and, hopefully, close this performance gap.