A system to mix audio signals, comprising: a data processing system comprising one or more processors and memory; a natural language processor component of the data processing system is configured to receive, via an interface of the data processing system and a network, data packets comprising an input audio signal (205, 305) detected by a sensor of a client device; the natural language processor component is further configured to parse the input audio signal to identify a request, the system being characterised in that, the data processing system comprises further: a digital component selector component configured to: receive the request identified by the natural language processor; select, responsive to the request, a digital component provided by a digital component provider device, the digital component provider device having an identifier; and a synthesizer component configured to: identify (215, 320) a plurality of audio chimes stored in memory of the client device; match, based on a policy, the identifier of the digital component provider device to a first audio chime of the plurality of audio chimes stored in the memory of the client device; determine (220, 330), based on a characteristic of the first audio chime, a configuration to combine the digital component with the first audio chime; generate (225, 335) an action data structure comprising the digital component, an indication of the first audio chime, and the configuration; and transmit (230, 340), via the network, the action data structure to the client device to cause the client device to generate an output audio signal based on the action data structure, the output audio signal comprising the digital component received via the digital component provider device and the first audio chime retrieved from the memory of the client device. a data processing system comprising one or more processors and memory; a natural language processor component of the data processing system is configured to receive, via an interface of the data processing system and a network, data packets comprising an input audio signal (205, 305) detected by a sensor of a client device; the natural language processor component is further configured to parse the input audio signal to identify a request, the system being characterised in that, the data processing system comprises further: a digital component selector component configured to: receive the request identified by the natural language processor; select, responsive to the request, a digital component provided by a digital component provider device, the digital component provider device having an identifier; and receive the request identified by the natural language processor; select, responsive to the request, a digital component provided by a digital component provider device, the digital component provider device having an identifier; and a synthesizer component configured to: identify (215, 320) a plurality of audio chimes stored in memory of the client device; match, based on a policy, the identifier of the digital component provider device to a first audio chime of the plurality of audio chimes stored in the memory of the client device; determine (220, 330), based on a characteristic of the first audio chime, a configuration to combine the digital component with the first audio chime; generate (225, 335) an action data structure comprising the digital component, an indication of the first audio chime, and the configuration; and transmit (230, 340), via the network, the action data structure to the client device to cause the client device to generate an output audio signal based on the action data structure, the output audio signal comprising the digital component received via the digital component provider device and the first audio chime retrieved from the memory of the client device. identify (215, 320) a plurality of audio chimes stored in memory of the client device; match, based on a policy, the identifier of the digital component provider device to a first audio chime of the plurality of audio chimes stored in the memory of the client device; determine (220, 330), based on a characteristic of the first audio chime, a configuration to combine the digital component with the first audio chime; generate (225, 335) an action data structure comprising the digital component, an indication of the first audio chime, and the configuration; and transmit (230, 340), via the network, the action data structure to the client device to cause the client device to generate an output audio signal based on the action data structure, the output audio signal comprising the digital component received via the digital component provider device and the first audio chime retrieved from the memory of the client device.