Take the 2-minute tour ×
Sound Design Stack Exchange is a question and answer site for sound engineers, producers, editors, and enthusiasts. It's 100% free, no registration required.

I'm trying to play binaural audio (generated by applying an HRTF based on sound source positions in a small game) over stereo speakers. Ideally, this would require cross-talk cancellation to be performed.

I've seen a lot of speakers which seem to reproduce 5.1-channel surround sound using two (or fewer) speaker units, such as Yamaha SoundBar or anything with Bose AdaptIQ. I would imagine that these models use HRTFs and cross-talk cancellation to position each channel in a 5.1 (or 7.1) stream to "virtual speaker" locations.

However, I am looking for speakers which can perform cross-talk cancellation (as part of their calibration process) and allow me to send 2 channels containing binaural audio, so I can get close to headphone-quality 3D reproduction. Are there any such speakers available today? I've tried looking at Yamaha's and Bose's websites, but there's not much information on what their technology actually does, beyond what has been filtered through their marketing departments.

share|improve this question

migrated from avp.stackexchange.com Jan 27 at 15:03

This question came from our site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation.

2 Answers 2

up vote 6 down vote accepted

First off, Cross-talk cancellation is actually a dangerous term here since it doesn't imply what type of crosstalk is meant, what you most likely mean is a 100% left-right channel separation. This is theoretically impossible, and I will explain why.

If what you are looking for is creating a wider impression than a stereo loudspeaker setup: The pseudo-surround (which in my opinion should never be associated with 5.1, both are surround techniques, and both are completely different) that a stereo set of loudspeakers 'implicate' is done by a technique that hasn't anything to do with HRTFs: it is done simply by doing magic tricks with the phase of the signal. If you listen to a well aligned pair of studio monitors, you can center a signal by putting it on both loudspeakers in phase. (0º). You can completely move it out of the loudspeaker base by inverting the phase of one of the speakers. (If your setup is correct, you won't be able to tell where the sound comes from.) You can move the source to the left by gradually decreasing the level of the right loudspeaker. The leftmost you can get is at the left loudspeaker, namely when you silence the right speaker. Now, if you put the same signal in counterphase (180º / inverted / ø) and gradually increase the level of the right speaker, the sound will move even further to the left. (i.e. sounds like it is further left than your left loudspeaker.) They never try to accomplish a 100% channel separation.

The reason why you can't separate channels acoustically is because the air the sound travels through is shared by both ears. (When listening to headphones, it is not, each small speaker has its own "environment".) You could be able to influence the sound that reaches your left and right ear with loudspeakers entirely, under two conditions:

  • You can never move, turn or tilt the head, not even half a centimeter
  • You must be in a room that has no reflections, since reflections reproduce the sound from an arbitrary direction.

The first condition is highly unwanted, but the second is completely impossible. (Unless you are in a dead room, but that is not where I normally am when listening for my own pleasure.)

Another technique that comes to mind being potentially useful for reproducing binaural stuff with loudspeakers, is Wave field synthesis. Unfortunately, getting a working WFS setup is very very very expensive.

Bottom line: why don't you just listen to your HRTF sounds using earphones? That's what they are for anyway.

share|improve this answer
    
Yes, I was indeed referring to 100% separation between left and right channels. It does seem theoretically possible, as discussed here. However, I had doubts about how practical it might be, and your points are exactly what I was worried about: the fact that there's a very small sweet spot, and that room acoustics would have to be cancelled. I guess I'll stick to using headphones for binaural audio (as I'm already doing), and have the user toggle binaural audio in the settings. –  Lakulish Jun 27 '11 at 20:21
    
Why not do it the hacky way and fashion your head a custom-fit Jecklin disc? ;-) –  Christopher Woods Aug 31 '11 at 3:12

The Jawbone JAMBOX just received a firmware update that enables binaural playback:

http://jawbone.com/liveaudio

Most Apple stores stock the JAMBOX, so you can demo it there if you're near to one of those. Good luck!

Disclaimer: I work for Jawbone.

share|improve this answer
    
The sketchy information on the JAMBOX site appears to infer that the device just employs psychoacoustic virtualisation, not binaural reproduction as the OP was asking about. I did some digging based on the smalltext disclaimer that the JAMBOX employs "BACCH™ 3D sound technology" and found princeton.edu/3D3A/BACCH_intro.html - you should have linked to that, there's technical papers and lots more detailed info on there. Your disclaimer notwithstanding, I initially went to downvote your response as it wasn't sufficiently detailed. (Please supply more info and references!) –  Christopher Woods Aug 31 '11 at 3:17

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.