EARLab is proud to be a part of new paper with the Medical University Hannover and Advanced Bionics!
Nogueira, W., Litvak, L., Landsberger, D. M., and Buchner, A. (2016). "Loudness and Pitch Perception using Dynamically Compensated Virtual Channels," Hear Res. epub ahead of print pdf
Previous work has shown that using two electrodes simultaneously can create what is effectively an electrode between the two phyiscal electrodes (i.e. a "Virtual Channel" or an MPVC). This is the trick that Advanced Bionics uses to create 120 channels with 16 electrodes using Fidelity 120. Current focusing (like tripolar stimulation) does not increase the number of channels, but can make the each of stimulation from each electrode more "accurate" (i.e. a reduced spread of neural excitation) as shown in Landsberger et al. (2012) and can produce better speech understanding in noise as shown in Srinivasan et al. (2013). In our lab, we have previously combined the virtual channel concept with current focusing using a stimulation mode called the Quadrupolar VIrtual Channel (e.g. Landsberger and Srinivasan, 2009).
While current focusing is quite promising, it is also power inefficient and can drain a battery quickly. In the current paper, a new stimulation mode (the Dyamically Compensated Virutal Channel or DC-VC) is presented which is designed to provide current steering (like a virtual channel), current focusing (like tripolar stimulation), while being more power efficient. The trick is to "dynamically" control the amount of current focusing depending on the amplitude / loudness of the DC-VC.
Please take a read of the paper!
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