silly question

[Gump]

Alright, It's silly question time...

How are sound engineers able to take different sounds (voices/instruments) coming from the L/R channels and place them in various spots across the soundstage? I guess this is called "imaging" but they might as well call it magic to me.

A specific example: I decided to stroll down memory lane and bought the new John Fogerty CD "The Long Road Home" which is basically a best of Creedence collection. So I'm sitting there listening to John sing the daylights out of the first track "Born on the Bayou" when I noticed something interesting. At about the 2 minute and 38 second mark of the song someone starts beating on a cowbell with a drum stick coming directly from the left speaker. About a minute later that cowbell starts to move slowly and methodically from left to right across the wall until it stops in the center. About a half a minute later it continues on across the wall until it stops in the right speaker where it stays for the rest of the song. Now that's magic!

OK, so I've got too much time on my hands...

I'm sure there are other songs out there that the music flip-flops back and forth between the L/R channels , but this struck me as being very distinctive with how it moved.

Anyway it kinda fascinated me so I became curious about the way they accomplished it. Hopefully the answer will be a little more exciting than someone simply walked from the left microphone to the right mic in the studio during the recording process.

Any comments about my speakers being haunted or how much alcohol I might have consumed prior to this phenomenom taking place will not be received politely. :

[wildfire99]

Visit: http://www.silcom.com/~aludwig/EARS.htm

Scroll down to the "Source Location" section. A quick preview:

An important characteristic of a sound system is the "sound image." An ideal system would create a vivid illusion of the location of each musical instrument. In designing a system it is important to understand, as well as current knowledge permits, how we locate the source of a sound. One thing that is clear is that the brain processes several different types of data to extract directional information. The data include:

* shape of the sound spectrum at the eardrum
* difference in sound intensity between the left and right ears
* difference in time-of-arrival between the left and right ears
* difference in time-of-arrival between reflections from the ear itself

[Karma]

HI wildfire,
Good link. Thanks.

Sparky

[Burke Strickland]

That link points to a reasonably detailed yet approachable discussion of the science behind the topic at hand. It is also a good reference since it isn't selling anything.

I'm sure there are other songs out there that the music flip-flops back and forth between the L/R channels , but this struck me as being very distinctive with how it moved.

If they "flip-flop" the sound too much, it sounds hokey, like they are shouting "see what I can do with my toys" instead of engineering a valid musical experience. On the other hand, there are times a shift in aural location makes a valid artistic statement and can add to the excitement, mystery, enjoyment of the music (Pink Floyd's "Dark Side of the Moon" has several examples).

Since most recordings are made with multiple mikes/tracks, often with each major instrument having a dedicated one, it is relatively easy for a recording engineer to "play tricks" with location by simply feeding that instrument into the channel they want it to appear in, and then to change the location, they switch (or pan) the input. Making it "believable" (fitting into the "space" if that's not where it was located during recording, and sounding like it belongs there) is where art and science overlap.

Anyway it kinda fascinated me so I became curious about the way they accomplished it. Hopefully the answer will be a little more exciting than someone simply walked from the left microphone to the right mic in the studio during the recording process.

Actually that is often what happens -- especially with opera recordings or highly staged rock concerts -- they are simply capturing the movement of the performers on stage. TIP: If you hear footsteps on the stage... :>)

Even when and if we understand "how they did it", the whole idea of recreating a musical performance in our homes without actually having the musicians present is still "magic" in my book.

Enjoy!

Burke

[Gump]

Very informative and interesting replys..thanks.

I still suspect a little hocus-pocus though! :E

Then again, I don't fully understand how my micro-wave heats up a bowl of soup in less than a minute, but I still enjoy the soup, and that's the main thing!!

[ToddAnisman]

Very informative and interesting replys..thanks.

I still suspect a little hocus-pocus though! :E

Then again, I don't fully understand how my micro-wave heats up a bowl of soup in less than a minute, but I still enjoy the soup, and that's the main thing!!

Well...There's no hocus pocus. In a stereo mix, each channel strip has what's called a "Pan" knob. This knob places the signal Left, Right, Center or any place in between. The audio Mixer justs reaches over and grabs it. In more advanced studios, there is an Automation system which can record and playback the moves of the Panners, Volume faders Eq's etc. There are actually motors attached to the knobs and Faders !!!

-Todd A.

[wildfire99]

Of course more and more people are using electronic mixing boards, which make automation a little easier. What I still find extremely trippy and almost hocus-pocus-like are binaural recordings, where the mic is inside the ear and picks up sound already properly scattered by the ear structures.

As to microwaves, it's a very simple process: http://home.howstuffworks.com/microwave.htm

And it all started with the magnetron: http://home.nycap.rr.com/useless/microwaves/