It is provided an electrode extension assembly comprising: a fastener for releasably fastening the electrode extension assembly to a user； a device holder for releasably holding a portable sensor device configured to capture electrocardiogram signals and audio signals； at least two extenders extending radially outwards from the device holder, wherein each extender comprises: a connector configured to connect to a respective electrode of the portable sensor device； an outer electrode connected at a distal end of the extender, the outer electrode being configured to be applied to a user； a conductor connected on one end to the connector and on the other end to the outer electrode； and an audio signal conveyor for conveying audio signals from the user to an audio sensor of the portable sensor device.
