What’s That? Binaural Audio
I’m sure that by now many of you have stumbled upon binaural audio. No, I don’t mean the binaural beats which give you the healing power of Jesus at 13 Hz. I’m talking about audio information with HRTF imposed on the signal!
HRTF … HRWTF is that ?
Good question! HRTF stands for “Head Related Transfer Functions” and is essentially composed of two different binaural cues - Interaural Time Difference (ITD) and Interaural Intensity Difference (IID) (Cheng and Wakefield, 1999).
Cheng and Wakefield describe ITD as the time difference of a sound source arriving at your ears, whilst IID refers to the amplitude difference of a sound source arriving at both ears. With the information from both, our brains have evolved to pinpoint sound, and the accuracy of this sound localisation has been subject to many tests over recent years.
If you’re a casual reader of this blog I apologise for the harvard referencing, this author is taking no chances with his university assignments. I much prefer the sleek number system that the AES use too …
Pretty cool stuff ! … So how are we using this in our modern technologies?
Binaural panning technologies can be used to create truly immersive soundscapes that trick the listener (wearing good headphones) into really feeling that they are in the scene. For example, below is a video of somebody demonstrating one of the best plugins on the market - dearVR Pro.
Listen to it with headphones!
The panning automation on the bike feels really uncanny. Unfortunately this technology does not work very well at all through speakers (due to loss of localisation, plus the resulting unnecessary timbre artifacts from the HRTF filter), rendering situations where the use is rather limited on certain formats.
However, with the emergence of VR headsets comes a new market which is growing at a huge rate, hungry for immersive audio.
Facebook 360 Spatial Workstation is a new software, using ambisonics in tandem with 360 VR video technology to create an immersive and reactive soundscape.
As you can see from the video, this method is a rather complicated process which is quite far removed from the simple panning automation utilised by dearVR Pro. However, the results are astounding, as fully immersive audio can now be (relatively) easily programmed to VR & 360 immersive video applications using ambisonics.
Unfortunately, as much as I’d love to play with this technology, I don’t have a 360 camera or an ambisonics microphone.
However, using the simple & free version of DearVR, I attempted to create a soundscape of my own!
Feel free to check it out in the video below. The video is supposed to be you, the poor listener, being serenaded by me and my ghostly (but handsome) minions having a jam in my studio room. Please excuse the terrible video editing skills !
Since the video is only static, I tried to incorporate as much movement as I could using song arrangement and automating the panning on the DearVR Micro plugin. Also, I hope that door knock caught you off guard !
Thanks for checking out my latest post ! Let me know what you think down below :)
References
Cheng C., Wakefield G. (1999). “Introduction to Head-Related Transfer Functions (HRTFs): Representations of HRTFs in Time, Frequency, and Space”. AES Convention 107, Paper 5026.
Link: http://www.aes.org.salford.idm.oclc.org/e-lib/browse.cfm?elib=8154
