A handheld display device for imaging a printed substrate and controlling playback of audio associated with the printed substrate. The device comprises: an optical sensor for imaging an area of the printed substrate and for generating image data; a processor for determining interaction data using the image data, the interaction data identifying a substrate identity; a transceiver for retrieval of audio data corresponding to part of the printed substrate; a touch-sensitive display screen for displaying display information identifying the audio together with at least one static element for controlling audio playback; and an audio output means for outputting the audio based on said retrieved audio data. Interaction with the static element via the touch-sensitive screen controls audio playback.