The effect of audio cues and sound source stimuli on the perception of approaching objects

Abstract

Objects that move in depth on an approaching trajectory (looming) are often encountered in both the real and virtual worlds. Examples include navigating oncoming traffic, and sporting and gaming activities where judgements are made to avoid or attack approaching objects. How people react to looming objects may impact on their survival and progression in the real, virtual, and gaming worlds, and relies on a person’s ability to precisely interpret movement and depth cues. Psychological studies investigating auditory looming often depict an object’s movement using simple audio cues (primarily amplitude increase) which are applied to tones (often sine or triangle waves) which are not normally encountered in the natural world. Whilst these studies provide valuable information about human perception and responses, technological advances allow us to present complex auditory stimuli with a range of audio cues and real-world sound sources, and to collect measurements on human perception and responses to ecologically valid stimuli.In this study we investigate human responses to audio cues for movement in depth, and how the cues affect people’s responses to the approaching object. We present an experiment on human perception where observers respond to auditory looming stimuli with real-world sounds that contain multiple audio cues, and introduce the direct-to-reverberant sound energy ratio as an audio cue. We measure the participants responses to the stimuli, asking them to indicate the approaching object’s perceived contact time (measuring their amount of over-/underestimation); to rate their emotional (valence and arousal) responses; and to rate the engagement quality of the stimuli. Our results show that listener’s responses to the audio cues differed, revealing a hierarchy across the individual audio cues, with the amplitude increase being the most dominant cue, followed by the direct-to-reverberant energy ratio. The results also demonstrated that conditions with multiple audio cues prompted earlier estimates of the contact times, greater arousal and engagement ratings, than single audio cues; and that real world sound sources prompted significantly greater engagement ratings than both the artificial sound sources.