The present invention relates to a head-mountable information processing apparatus allowing a user to hear a desired sound even if ambient sound unnecessary for the user is present. An audio input interface includes sound microphones worn in the vicinity of the user's ear, collects the ambient sound that occurs outside the head-mountable information processing apparatus, and converts the ambient sound into an input audio signal. An audio output interface, including headphones, converts a generated output audio signal for output, and emits the audio output toward the user. Based on a volume level of the input audio signal and a volume level of the output audio signal, a controller determines whether or not a state in which the ambient sound is preventing the audio for output from being heard is occurring, and based on a determination result, the controller controls a sound emission operation of the audio output interface.