A computer system comprising: one or more processors configured to: receive a stream of data from a plurality of network connected devices configured to measure physical parameters, each network connected device having an associated location; determine that trigger conditions for a plurality of candidate notifications are met based on the received stream of data; determine audio rendering characteristics for a plurality of candidate notifications; generate a composite sound output including a plurality of component sounds associated with the plurality of candidate notifications rendered based on the determined audio rendering characteristics; and send the composite sound output to be played to the user via a speaker system, characterized in that the one or more processors are further configured to store a user profile for a user, the user profile including user settings for a plurality of notification subscriptions associated with physical parameters measured by the plurality of network connected devices, each notification subscription including programming logic for a trigger condition for the candidate notification based on measured physical parameters and an associated component sound for the candidate notification; the audio rendering characteristics for the plurality of candidate notifications are determined based on a detected location of the user relative to the associated locations of the plurality of network connected devices; the speaker system includes a near-ear speaker worn by the user and configured to output spatial audio; and the determined audio rendering characteristics include a spatial audio rendering characteristic configured to localize each component sound being played by the near-ear speaker to the associated locations of the plurality of network connected devices relative to the detected location of the user, wherein the determined audio rendering characteristics specify a location of a virtual speaker where each component sound will be localized, and the near-ear speaker is configured to play the spatial audio for that component sound such that it is perceived by the user as originating from the location of the virtual speaker. one or more processors configured to: receive a stream of data from a plurality of network connected devices configured to measure physical parameters, each network connected device having an associated location; determine that trigger conditions for a plurality of candidate notifications are met based on the received stream of data; determine audio rendering characteristics for a plurality of candidate notifications; generate a composite sound output including a plurality of component sounds associated with the plurality of candidate notifications rendered based on the determined audio rendering characteristics; and send the composite sound output to be played to the user via a speaker system, receive a stream of data from a plurality of network connected devices configured to measure physical parameters, each network connected device having an associated location; determine that trigger conditions for a plurality of candidate notifications are met based on the received stream of data; determine audio rendering characteristics for a plurality of candidate notifications; generate a composite sound output including a plurality of component sounds associated with the plurality of candidate notifications rendered based on the determined audio rendering characteristics; and send the composite sound output to be played to the user via a speaker system, characterized in that the one or more processors are further configured to store a user profile for a user, the user profile including user settings for a plurality of notification subscriptions associated with physical parameters measured by the plurality of network connected devices, each notification subscription including programming logic for a trigger condition for the candidate notification based on measured physical parameters and an associated component sound for the candidate notification; the audio rendering characteristics for the plurality of candidate notifications are determined based on a detected location of the user relative to the associated locations of the plurality of network connected devices; the speaker system includes a near-ear speaker worn by the user and configured to output spatial audio; and the determined audio rendering characteristics include a spatial audio rendering characteristic configured to localize each component sound being played by the near-ear speaker to the associated locations of the plurality of network connected devices relative to the detected location of the user, wherein the determined audio rendering characteristics specify a location of a virtual speaker where each component sound will be localized, and the near-ear speaker is configured to play the spatial audio for that component sound such that it is perceived by the user as originating from the location of the virtual speaker.