Abstract: A system for sensing in-ear electrical signals includes a left electrode tip, a right electrode tip, and a signal acquisition subsystem. Each electrode tip includes: an elastic substrate configured to conform against an internal surface of an ear canal of a user; a sense electrode, a reference electrode, and a driven ground electrode each arranged on the outer surface of the elastic substrate. The signal acquisition subsystem is configured to, during a sampling period: output a left time series of a left voltage differential between the left sense electrode and the right reference electrode; and output a right time series of a right voltage differential between the right sense electrode and the left reference electrode.