The Production of Steerable Binaural Information From Two-Channel Surround Sources

Conventional stereo recordings when listened to over headphones usually result in poor spacial imaging.2-channel surround formats can work to a limited extent as the surround information is in anti-phase in the left 8. right signals which confuses the auditory system of the brain, The brain tends to assume sources are above and behind the head when it is unable to place them due to con icting auditory clues.The brain is bad at telling front sources from back as the differences tend to be subtle hence these ambiguities are usually resolved by head rotations.ln headphone listening head movements do not result in a change in the signals at the ears and thus these ambiguities cannot be resolved.One solution is to use binaural recordings but a problem is that there are a low number of such binaural recordings available compared with stereo.These recordings also give poor imagery when listened to over loudspeakers (the hole in the middle effect).Virtual reality (VR) and telepresence systems [1] require audio and visual images which remain coherent for large head movements.Such systems are often helmet based and so headphones are used for the audio reproduction.VR head tracking systems are available commercially which give information on head position and orientation.If the head orientation signals could be used to steer surround audio then the imagery obtained from headphones could be good.The effect of the headphones on the conch resonance [2] needs to be compensated for as this is a potential source of lack of realism.What is required therefore is system that produces steerable binaural information from traditional sources.As most domestic audio products are two-channel it is these sources that need to be considered for home use.Nearly all the existing surround formats are horizontal only as full periphonics (with height) really requires more than 2 channels.