Abstract: An apparatus includes a viewer device wearable on the head of a user and including a display. The processor is configured to generate a signal prompting the user to exhale and determine whether audio signals corresponding to the sound captured by a microphone of the user exhaling matches a first audio profile. If the audio signals match the first audio profile, the processor determines whether position signals indicating the spatial orientation of the viewer device matches an orientation profile. If the position signals do not match the orientation profile, the processor generates a directional indicator to indicate to the user the direction in which the user should move the head so that the position signals will match the orientation profile. If the position signals match the orientation profile, the processor generates a signal prompting the user to inhale and determines whether audio signals corresponding to the sound captured by the microphone of the user inhaling matches a second audio profile.