Before revision:  We introduce semantic audio-visual navigation, where objects in the environment make sounds consistent with their semantic meanings (e.g., toilet flushing, door creaking) and acoustic envents are sporadic or short in duration.
After revision:  We introduce semantic audio-visual navigation, where objects in the environment make sounds consistent with their semantic meanings (e.g., toilet flushing, door creaking) and acoustic events are sporadic or short in duration.