3. The method of claim 2 , wherein: the mobile device comprises a head-mounted display device.
2. The method of claim 1 , wherein: the capturing a first audio signal includes capturing the first audio signal using a microphone; and the detecting that a first utterance has been spoken by the person is performed by a mobile device, the detecting that a first utterance has been spoken by the person includes applying speech recognition techniques to the captured first audio signal; and the displaying a sequence of images of the virtual object includes displaying the sequence of images using the mobile device.