Ever been confused / disoriented by phase shifting?

[Mark Hammer]

I think the best way to think about it is as the audio analog to the motion sickness you feel when in a bus terminal or train station, looking out the window of the bus/train you're on, and for a brief instant you can't tell if it's YOUR vehicle that is moving, or the other one.

This is actually a very good analogy because a number of the same principles apply. In the case of visual uncertainty, the nausea one feels really only happens when all the spatial information is coming from the relative movement of the two buses/trains, and you can't see anything else. Have those same two vehicles separated by a reasonable distance that allows you to see other things besides the other vehicle, and yo have enough visual information to triangulate and know for certain that it IS you or the other thing that is moving while the remaining one is still.

Similarly, there is almost always some degree of group delay (phase shift) in the audio spectrum, arising from one source or another. However, we are still in a position to hear enough from one or more predictable sources, that the varying ones don't confuse us too much. As a gedanken experiment, imagine processing the content above 3khz with through-zero flanging that sweeps across the stereo field, but keep everything below 3khz equally distributed (and in mono) between the two speaker cabs. You will experience very little disorientation whatsoever. Take the entire signal, though, and do the same thing such that you get your very best Eddie Kramer thru-zero flanging sweep (think the ending of Axis: Bold as Love) across the astereo field, and it is VERY disorienting.* Not nausea-or lightheadedness inducing, but momentarily spatially confusing.

[ERB]

I was way into psychoacoustics when I was in college. I did one experiment in EML lab with stereo delayed signals and phase shifting that would cause most listeners to almost fall off their chair. It was very dependent upon the listener being centered, almost perfectly, in relation to the speakers and really only worked if the listener was using phones. If you were not positioned perfectly, it just sounded like an out of phase signal.

I remember reading about one study, done in Germany, involving very low frequencies and phase shifting. They actually made some of the test subjects lose control of their bowels!

This would be hillarious to do at the SuperBowl next year. Right in the middle of half-time. Hahaha!!! The people in the sweet-spot would not smell so sweet!!!

[kingjj]

im not sure i felt spacially confused. not nauseated either. light headed is pretty good to me. my theory is that its caused by harmonic disruption in the nervous system based on the impulse speed of the nerves themselves. something simular to florecent lighting causing the same effect in some or even epileptic episodes. being that everyone has different metabolism and verious other facters that effect the "speed" our bodies function at. thats why the effect would be more common and more noticable/repetable in a sweeping frequency and phasing enviroment. also why we all might have varying reactions. i think this kind of thing happens way more than we all realize in our day to day electronic reliant lives. its just so short we miss it. also im a little surprised theres no mention of the southpark "brown note" episode.

[bob p]

OT:

I've never seen an entire episode of South Park. I tried to watch it once, but I changed the channel before the show was over. I didn't think it was funny. I can guess what the "brown note" joke might be about. I probably wouldn't find that joke funny either.

My brother and his kids love the show, because the characters are based on real people at the school in their home town. They think its really funny because they know the characters in real life. Not knowing those people, I'll never be able to enjoy the show the way that they do, so I just don't bother.

[Mark Hammer]

Nah. It's simpler than that. Just a momentary conflict between what you think you are hearing and what you expect to hear.

Buggering up phase in a rapidly fluctuating way makes it difficult for us to peg down where something is in the field, on the basis of auditory and ear-arrival cues. That's why I gave the example of the movement confusion with vision. Happens all the time.

Keep in mind that we identify the spatial location of things on the basis of a number of cues. Relative loudness is one, but so is phase, so is arrival time, and so is inter-ear differences in harmonic content. All of that is used for those "stereo image exhancers" like the Carver Sonic Hologram, that were popular in the early 80's, and eventually tranformed into stuff like the Q-sound software system. I have a couple of those units, and even built one, and they work quite well. You can close your eyes and literally "see" the person with the shaker or snare drum juuuust a few feet off to the left and about 4 feet above you. But of course, that is what you get when all the phase, arrival time, inter-ear difference information is provided in a consistent and coherent manner. Like I say, mess with it, and you hear things that can mess your mind.

[Hurricane]

Phase Shift My Cares Away As I Spiral My @$$ Down 2 Da Ground

Well for me it was first noticed when I went to concerts here in the mid and late 60s . I saw people sort of stand in place reacting to the the phase shift and many showed a distinct pattern as they literally would fall down and hit the deck and look like they didn't know what just happened at first .

The usual scenario was like this :

A dude or dudette , standing doing the " hippy trance dance " in one place feet not moving , sort of like a standing shuffle and then their upper torso would twist at the hips one way and their legs the other in a spiral to the beat and timing and sort of like do a " Leaning Tower Of Pizza " angled spiral towards the ground like these dudes and dudettes look like they are about to appear to end up doing below :




Now me on stage - - yeppers it's a very cool sensation and it's a legal buzz

I get ( got ) it on with phase shifters and digital delay . And I first noticed I could get it going when there were stoners more than when I played bars with alcoholics too . Also I did it with an :

Electrified Harp ( Harmonica - Blues type 10 hole diatonic )



smacked up tight to a bullet microphone

hooked to my Marshall 60 watt tube amp and Ibanes analog Delay HD 1500




Now a days I play electric guitar too and use it the same way only now I have a DAW with a full blown FX engine and stuff and well .............. you know ........... stereo ...........and stereo amps ....and well you know ......... live in front of stoner hippy types and well you know .........

Easy Peoples :

Hurricane Ramon

[Hurricane]

Size Dose Make A Difference !

Excerpt :

I've tried to re-create the experience a number of times, but I've never been able to duplicate as impressive an effect as I had on stage that night with the Bi Phase. I'm not sure which factors might be necessary to make it happen. We were playing on a full size theatrical stage. That was a huge platform that allowed us plenty of room to spread out our gear, so the guitarist's two amps were located far away from me on each side of the stage. We were playing in a huge gymnasium, which was a large, highly reverberant room with balconies on both sides, so there were many different large, highly reflective walls to generate complex reverberation patterns. I haven't played in a venue that large in decades. I'm wondering if the room played a large part in screwing with my head. Maybe it was the depth of the stage, and the size of the room that contributed a lot of natural / complex reverberation to the sound. Of course, part of it could have been that I wasn't playing the sounds that were confusing me. Maybe a large part of it was due to the fact that I was trying to do something entirely different on the bass, while I wasn't focused on making those phase shifted guitar sounds. Maybe it has a lot to do with concentration on what you're doing, and trying to block out confusing extraneous inputs. I remember the guitar player wasn't at all confused, but I was so overwhelmed by the distraction that my mind was turned to mush until he stomped on the off switch at the end of his solo.

I seem to remember R.G. mentioning something like this happening to him once upon a time. It would be interesting to see if he joins the discussion.

=======================================================

Oh Bob hey

Even with a mono set up you can get stereo type { Binarual } imaging in a big room , like a theater type set up like this :

With my harp , a bullet mic w/above set up . With a mic on my Marshall amp to the P . A . and my standing in and out of the " feed back " zone - you know what I mean where with a electric guitar goes in and out of the " Hendrix " zone so to speak .

Now as I do this with a harp & mic ( could be any type - you adjust ) and grab sound out of my Marshall amp with the mic this occurs .

The delay from the signal and then myself reproducing a second signal in phase creates a phase shift like a radar wave coming back and seen on a radar oscilloscope when it compares the out going signal with the reflected return signal in an " out of phase " image you clearly see -

Only with sound waves your ears are the radar oscilloscope and it's your ears that sense and feel this out of phase shifting physically and we all know that the auditory system in our ears includes the sense of physical balance for us .

This is real man , I still do it to . Sometimes just a good P . A . with a decent DSP straight into it and the house P . A . speaker system - it can get really wild .

So .........

when I got to stereo gear finally it was even easier to "dial " it in , Not at all the same but still so close you can feel the similarity's when listening as I play with each side by side in tests I have done .

With the Binaural type approach you can also do other stuff like for instance :

Create a sense of throwing the sound like a ventriloquist does - sound strange huh and impossible but nope - - it can be done .

Do that as you get the " Doppler effect " going as you get into that Hendrix zone and as you play in and out of it while you stand and rock and teeter about it and it get's going you pull away really fast and like a break in a song to give the song some dynamics you jump back into it and if done right in just the right sized big room and there are hippy types there doing the hippy trance dance - -

Well you know .......................


Easy man Good post :

Hurricane Ramon

[Groover]

IIRC 40-80ms hard to one side and half the delay time hard to the other side (20-40ms) and a tiny bit of dry right up the middle would really get things swimming.

I have seen this term/string "IIRC" in several different posts in different threads. Is is an acronym? What does is stand for?

[bob p]

FYI:

IIRC

HTH.

[Groover]

Thanks, I was thinking it might have to do with electronics since it sort of resembles pi*R*C