A Systematic Review of the Methods and Experiments Aimed to Reduce Front-Back Confusions in the Free-Field and Virtual Auditory Environments

Human spatial representation is determined by the interaction of a wide range of stimuli, including visual, neuromotor and acoustic information. In a virtual acoustic environment that intends to simulate the perception of sound as in real-world conditions by rendering the audio stimuli over headphones, the accuracy of audio presentation is of the utmost importance. Nonetheless, a well-known problem which affects binaural audio localization is represented by the front-back confusion, a situation in which the listener perceives the sounds which come from the front as coming from the back and vice-versa. Over the years, many theoretical and practical approaches have been devised in order to reduce the incidence of front-back confusions, including head movement, source movement, sound filtering using early reflections, the simulation of reverberant environments or anthropometric estimation. This paper aims to study, review and compare the most relevant methods and experiments designed to decrease the rate of front-back confusion errors that appear in the case of synthesized 3D sound delivered over headphones in virtual auditory displays and in real-world conditions.