[baglunch]

Hm, that sounds a lot more specific than what I have in mind. Like, specific to a particular room, and to a particular person, sort of like the Smyth box.

I'm not so interested in acoustically modeling a room, making my headphones sound just like my speakers (or someone else's) or even trying to get that violin to be just to the left of the right speaker. I just want to be able to turn my head a bit and have the sound seem like it's staying in the same place. I am thinking the "place" the sound is coming from could be whereever you have the tracker located. I don't mean to make it sound like the sound is coming from a small radio in front of you, I just mean, lock down the soundstage. So you can set it on your desk in front of you, put it on top of the tv, etc. Whereever. Would even be kind of fun to wave the tracker around, like a baton. Not so much how you'd really want to listen to your music, but fun for a couple moments. I'd want to be able to take this system with me from home to the office, where I sit in a large open area with lots of other desks... where it would be unreasonably difficult to do your incremental readings system, with everyone trying to work. I'm imagining an infrared LED over each earcup of the headphone. An actual Wii remote for the sensor / tracker. And a program running on the computer (or a black box, for non-computer-as-source-types) to interpret your head's location and orientation based on the Wiimote's info.

My problem in trying this out, is I can't code. This may be the part where I am overlooking some large flaw in my cheap and simple chain of logic. I have friends that code, but none that have any background in audio or position tracking or anything like that. I'd think someone that programs for the Wii would be a great source to ask about... but I don't personally know any, so I'm broadcasting my idea here to see if anyone that stumbles across this thread (like you) can give feedback.

Can you tell me where my idea falls apart? How would it not work much more easily than the multitude of readings method you describe?

 

[BradJudy]

In effect, this has been done. There are many games (like FPS) that define sound sources as positions in 3D space. There are head-tracking units that can be used with many games (more popular with flight sims than FPS). If you combine the two, then have the "monsters" in the games playing musical instruments instead of growling, you're done. In theory, it would not be hard for the game developers to do this. However (big but here) there isn't any music recorded in this manner. This would require not only individually mic'ed instruments (common in most music, but uncommon in an orchestra), but also recording the relative physical position of each source.

Certainly the Wiimote is a potentially good way to do this since it's an inexpensive bluetooth capable IR camera and as linked, it has been used for head tracking. I have done the head tracking and touch-screen Wiimote demos as shown in those videos (it's pretty easy since he provides the software - assuming you know how to swap IR LEDs in to LED keychain lights).

 

[baglunch]

Quote:

Originally Posted by BradJudy /img/forum/go_quote.gif This would require not only individually mic'ed instruments (common in most music, but uncommon in an orchestra), but also recording the relative physical position of each source.

Why?

In non-headtracked music, the instruments already give you a sense of where they are in a virtual 3D space around you. I don't mean to be able to walk up to the saxophone and hear him louder than the bass player, I just mean move your head side to side, turn it side to side, and the band still seems to be where it was. Like looking at a picture that wraps around you. It's painted to look like it has depth, but no actual doppler effect as you turn or move around to see it.

 

[BradJudy]

Quote:

Originally Posted by baglunch /img/forum/go_quote.gif Why? In non-headtracked music, the instruments already give you a sense of where they are in a virtual 3D space around you. I don't mean to be able to walk up to the saxophone and hear him louder than the bass player, I just mean move your head side to side, turn it side to side, and the band still seems to be where it was. Like looking at a picture that wraps around you. It's painted to look like it has depth, but no actual doppler effect as you turn or move around to see it.

Well, if that's all you want, then it's more simple. It's just a pair of sound sources acting like virtual speakers. I expect it wouldn't be too hard for a game developer to create this environment (two sound sources using mp3s as the content), assuming you had the head tracking equipment and the equipment worked with the game.

Of course, that's a lot of resources (time and $$) to just mimic the effect of rotating your head in front of speakers while wearing headphones. If you're lucky, perhaps you can find a headphone junkie audio/gaming programmer who can build on the Wiimote work, but otherwise I don't see it happening on the cheap in the near future.

 

[calcetin]

Quote:

Originally Posted by baglunch /img/forum/go_quote.gif Can you tell me where my idea falls apart? How would it not work much more easily than the multitude of readings method you describe?

Yeah, it´s absolutely boring

. The problem is, before any head-tracking, first you need to hear the sound coming from a source, or direction, because with headphones, normally, you would hear the sound coming from your head.

The easiest method is through convolution.

If you use a PC, install winamp and this plug-in
http://www.winamp.com/plugins/details/7630

It´s a convolver, it comes with some Impulse responses, search for some binaural impulse responses in Google and use them with this plug in.

 

[AaronBroad]

Quote:

Originally Posted by baglunch /img/forum/go_quote.gif ... I just mean move your head side to side, turn it side to side, and the band still seems to be where it was....

This is what the Smyth and Headzone systems do - you can turn your head and the virtual speakers stick to their locations. If you are trying to walk around the room and turn your head from side to side then that does get trickier.

I think you would need to take into account the following in order to make something work:
1) The amplitude and frequency of the original sound,
2) The distance and angle of that virtual speaker's sound relative to the user (accomplished by the Wiimote or some other headtracking system)
3) Room / reverb effects for the virtual room you are listening in.
4) HRTF - the impact of the frequencies as they are played around the users' head, to give the user the impression of sounds coming from in front and behind them, instead of purely left and right. This is what the Smyth system effectively measures as part of the calibration process, and other systems (Headzone and Dolby Headphone) model one way or another. Without this, all sounds coming from the right side sound the same (assuming a dead, no-reverb room) whether coming from the right front or right back.

Forgetting about how to do something like this for a moment. I want to know why bother. To me this kind of technology doesn't really appeal as I think about watching a movie or gaming. If I'm on the left side of the room, I still want the sounds from the left of the screen to be clearly on the left, centered on the display. I don't want it to sound like everything is coming from my right as it would if the speakers were glued down somehow. Effectively I want the virtual room to move to where I happen to be sitting. Perhaps there are some exceptions but I can't think of them off the top of my head.

 

[rwest1389]

Here are some of my ideas, likely all off, so correct me if I am mistaken
but,
the recorded audio from a band may be compiled from different instruments (it really always is) but once its compiled (not sure how they do it but nevertheless) you're left with stereo sound, meaning left and right. If I understand the OP's idea correctly, he just wants these to be rotated as you rotate your head.
I think, unfortunately, that this could be achieved, but result in only blurred sound. Your brain deciphers where sound is coming from through time delays, and experience of knowing that something behind you sounds more muffled than from left or right. So, if you were to virtually rotate the soundscape, that sound that was muffled to create the appearance of it being in front of you (if it is recorded and processed that well) will remain muffled even from the sides of you. I don't believe you could 'sharpen' the sound any to make it sound like its right to the side of you. In the end, even if my details aren't exactly right, I think you would have a real distortion of the sound, as once the sound is processed into stereo, you won't be getting anything back. You might be able to make it sound like the instruments are coming from somewhere else, but it probably won't sound natural at all.

One possibility I can think of though is if you're audio file is in surround sound format. Then a processor could in a way convert how surround sound speakers would sound into headphones. This doesn't seem to hard in theory, but its applications would be very limited, as most audio files you have aren't surround sound.

 

[Omega]

The devil is in the details!

Good idea, now think about HOW you would implement it. Lots of good hints above...

If you can write down a recipe on a piece of paper, you can program a computer. Just a matter of learning the syntax, spending time developing "scar tissue" as you learn, and building up your expertise. The challenging (and rewarding) part is solving problems in an algorithmic and elegant way.

Anyway, this sounds like a good opportunity to learn! My suggestion: start with Fortran or C and learn the right way

 

[baglunch]

Hey all, thanks for the continued suggestions. I'd thought this thread was dead and I stopped checking on it (but I've continued dwelling on it privately). oops!

My reason for wanting this is additional immersion. You have a nicely recorded piece of music, you can almost pick out exactly where all the band members are sitting. It's like you are there. And then you turn your head the slightest amount and the illusion is broken. A band simply does not rotate with your head in real life. Nothing does. With headphones, the way you experience sound is utterly different than at any other time in your day and life, and it simply cannot be immersive unless you hold quite still, which is impractical most of the time.

The only way to preserve your impression of where things are (yes, basically just simulating listening to a pair of speakers in the room) is to have things seem to stay where they are when you move. To make them seem to exist independent of you. It strikes me as being vastly more immersive. Well, the idea does, anyway. I've never heard it with headphones. I've heard binaural recordings which are really good as long as you hold your head very still, but imagine how much better they'd be if you could turn your head and "look" at the barber trying to cut your hair, or "see" the drummers or the fireworks in the ultrasone CD. It's how we are used to experiencing sound in the world, and I think the Wii solution is a cheap(ish) way to get this.

As far as cost goes, yeah, it would be retardedly expensive to accomplish this for just myself, having no programming or circuit-building experience. I'm starting to think of this as a business idea. I can't help thinking this is such an obvious improvement in how you experience music through headphones (or audio books, plays, etc. where they make use of positioning in the soundstage with footfalls and other sound effects). And if it can be cheap enough ($100?) when mass produced and can be done transparently enough, I think there might be a lot of people wanting to check it out.

People frequently complain about headphones sounding like the sound is coming from inside your head. I think a lot of that is the constantly destroyed soundstage from turning your head, not being able to experience the sound the way you are accustomed to doing the rest of your day. This would be a great step to defeating that. If it can be done cheaply.

It turns out that it's already being done really expensively (with more bells and whistles). But if you aren't looking to simulate a particular sound studio, a particular set of speakers or headphones, if you just want to lock things down in space, I think I'd want it. I think most people who have headphones would want it if it was cheap enough. The scary part is actually believing in the idea enough to get the ball rolling. I've got 2 kids and a busy job, I've got no time left for learning programming. I learned a little C++, a tiny bit of assembly. I know just enough to know how much farther I'd have to go before I could be useful to myself.

If there are any programmers reading this thread that might be interested in this idea, send me a message. If there's anyone else still reading this thread, please continue to give your thoughts and criticisms. If you can come up with a show-stopper roadblock for this, you'll save me a lot of time and money.

 

[AaronBroad]

I agree that there would be a great market for a system like the [showUID]=2107&tx_sbproductdatabase_pi1[showUid][backPID]=2026&cHash=c604bfb18b]Beyerdynamic Headzone system if it were priced affordably (and not $2,000+).

I think an interesting product would have the following attributes:
- works with any set of headphones
- Dolby Headphone technology to virtualize the surround sound (not customized to an individual's HRTF, but it does a respectable job for most users)
- an unobtrusive headtracking device that attaches to any set of headphones
- base station - should take a digital 5.1 signal from a source and output the DHed, headtracked signal directly with a headphone out (requires at least a decent onboard amp) or unamped for those that want to route through their own headphone amp.

I can think of a bunch of other things I could wish for, but those are the basics that I think would be required. Folks feel free to comment as you see fit.