Hola amigos, I would like to share this curious video with you. This aural illusion was created by QSound, company which designs audio solutions for 3D and surround positional audio. Despite It is not as simple, I will try to explain how this illusion works:
Individuals are able to localise objects in their environment by the binaural hearing, which is the tridimensional sensation created through the comparison of the information related to amplitude and time lapse received by each ear. In other words, each ear processes the volume and the phase separately and brain join the data to identify where the sound source is.
The information gathered for each one differs not only due to physical conditions of a receptor like the separation between both ears, the shape and the size of the head or the sound’s resonance in the space between our chest and shoulders but also, the sound’s incidence and reflection on the environment.
The time-based differences lead to the angle of the source respecting the front’s center, provided that the information is similar for both ears (It is identified as a the same sound) and the delay is not more than 50 ms (otherwise, it will be interpreted as two different sounds). For example, if the sound is perceived on the right ear before the left did, the brain will mentally place the source to our right. The amplitude-based differences lead to the distance between source and receptor; while loud sounds will be perceived as closer, low ones will as further. In addition, the amplitude can give information about the position by comparing the loudness received by each ear; if the right ear perceives a sound stronger than left one, the brain will place the source in the right side and vice-versa. However, there are multiple factors affecting the subjective quality of a sound and these are determinant for locating a sound.
Playing with all these parameters, some audio researchers and companies specialized in sound has come to investigate new ways to simulate spaces based on the way we perceive a sound in order to provide the most realistic and thrilling experience. Hope you enjoyed your virtual haircut!
KANE, J.W., STERNHEIM, M., Physics, John Wiley & Sons, 2000, p. 523
RUMSEY, F. MCCORMICK, T., Sound and Recording, Focal Press, 2009, p. 37
LITOVSKY, R.T., “Binaural Hearing”, Cochlear, 2015, available in Cochlea.com (Accessed in 22 Octover 2015)