This applications relates to methods and apparatus for monitoring a socket (101), to detect a connection status of a mating plug (102), e.g. for monitoring an audio jack socket for connection of an audio jack plug. A monitor (115, 305) is configured to monitor a voltage (VM) at a monitoring node (114), which is coupled to a jack detect contact (112) of the socket and a voltage pull-up element (113). The voltage (VM) at the monitoring node (114) is monitored against a threshold (Vthv) and a threshold module (302) is configured to vary the threshold depending on an indication of signal activity (SACT) of a signal path for a first socket contact (103) which will be electrically connected to the jack detect contact when a plug when inserted in the socket.