Aspects of the present disclosure provide a method for obtaining biological information associated with a user, comprising receiving electrical signals via a first electrode on an ear tip of an earpiece inserted in an ear of the user, receiving electrical signals via a second electrode on an external portion of the earpiece, and deriving an electrocardiogram (ECG) based on the signals received via the first electrode and the second electrode. Aspects also provide a method for determining a pulse travel time (PTT) associated with a user, comprising obtaining a proximal signal using an earpiece inserted in of the user, obtaining a distal signal using the earpiece, and deriving the PTT based on the obtained proximal signal and the obtained distal signal.