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[benn600]

Has anyone else noticed that when a song is sped up via the tempo setting, the singer (especially) ... (best noticed when using headphones) moves around in a circular 3D pattern?  Perhaps that's how Dolby has Dolby Headphone?!  It is not necessarily bad and I kind of like it but perhaps a checkbox to disable it would help....

Is it something to do with the decoding process that when things are sped up the channels are not mixed properly?  It just sounds like singers, which are often mixed equally to both channels so they appear in the center, are getting shifted to RIGHT, LEFT, CENTER, etc...just continuously and smoothly going in circles.  Try it and tell me what you think.  I find it noticeable right now on the last 5 songs I've played (so most music I'd say) with vocals and I'm at +0.11 tempo but +0.22 also revealed this well.

Try it and tell me how crazy it is!  Don't just "fix" it and take it out (if that's possible) because this is neat.  It livens up music.  The singer is runnin' round.

[InflatableMouse]

Thats a phase shifting effect and basically is how 3d effects work.

I used to do that with a tape recorder and cd player, play the same thing simultaneously, but the tape would speed up and slow down slightly so it would shift in and out of phase with the cd player creating this really spacey effect. A good smoke would greatly enhance the experience

[benn600]

I have heard a lot about the phase of audio, speakers, etc, but I'll need to research a bit to understand it completely.  So is there a way to disable the phase changes?

[benn600]

Nope, I really think it's just that each channel is adjusted slightly differently.  That would make sense and is supported by some reading I just did.  It makes sense very much because if a person is to the left of you, your left ear will hear the sound slightly sooner than your right ear (and the volume would differ, too).  So perhaps each channel is simply not adjusted at exactly the same moment in time...

[InflatableMouse]

Of course its a lot more complex than just a slight delay in one channel. I don't know the details, but it was once explained to me by a sound engineer at Universal Studios where I used to work (at the IT department).

http://en.wikipedia.org/wiki/Phase_(waves)

The phase shift is the difference between wave A and B. For a simple wave, lets say 120hz, if the frequency of either wave would be slightly off they will move in and out of phase and meet in the middle. This creates sort of a hollow effect, kinda spacey alien, sorta, weird, kinda effect  hehehe.

I believe he said this technique was used in combination with virtual sound imaging, also called crosstalk, to create a 3d soundstage. I quicly found this http://www.isvr.soton.ac.uk/FDAG/VAP/index.htm.

The best example I know of is a CD is by Roger Waters, Amused To Death produced at Q-Sound studios. With a proper setup, this CD will completely surround the listener, including above, below and behind the listener. Really weird and very cool. I always use that CD as a reference for setting up speakers at peoples' homes. Not that I do that very often, but when I do, I make sure I use that CD to determine speaker placement. Once I had to really convince a visitor I wasn't using my surround speakers. He really thought I was fooling him

[benn600]

I'll have to add that to my list of CDs to buy.  thanks