They could easily replicate the doppler effect and play that through a few speakers following the original sound, couldn't they?

...Except you all need to listen to it again. On the long straights, there WAS a doppler effect. It may have been manufactured. But it was there in the video.

Listen again.

I suppose you think your television set has little people inside of it as well.

I don't like to get involved in discussions like this, usually, but this has gotten silly. The Doppler Effect is produced by the movement of the sound source which alters the wave length and therefore the frequency of the received sound even though the source frequency and wave velocity are unchanged. In this case, the sound is moving by electronic manipulation of the source through sequenced speakers. The acoustics of the venue have no idea if the source is a moving object or not, and do not care. A listener in a fixed position at the track would most certainly hear the effect.

-e.

Nothing is moving on the track. The speakers are just sitting there stationary, reproducing a pre-recorded sound. Therefore, no effect. Any doppler effect heard on the video is built into the sound track and would only sound correct from one position on the track.

To do this properly, with a true doppler, you would have to play the sound of the car (without any built-in doppler) from ONE speaker and then drive this speaker around the track at the exact speed of the original car. THEN you would have your moving sound source and a true doppler effect.

The speaker must also disperse sound 360 degrees...

If the sound was able to be reproduced digitally, IE as a digital file (like a MIDI file), then multiple speakers could "relay" the sound down the track, very similar to what's happening with the lights. The doppler effect could then be achieved, although without the same "resolution" as would be achieved with moving a single sound source down the track.

Edit: Nope, that wouldn't work either, since the sound source is not truly moving.

You guys are too much! Believe what you like. :)

Please explain in detail how we are wrong. I truly want to understand this and would love to be proven wrong, but my brain refuses to accept how a stationary speaker can create a doppler effect. The speakers are all vibrating to create the engine sound, but they are not moving in relation to the listener, assuming the listener is stationary. The perceived "motion" of the car is simply a sequential volume swell of consecutive speakers, giving the illusion that the sound source is moving. It's no different than rapidly turning the balance knob on your stereo -- the perceived location of the music changes, but the sound of the song stays the same.

What am I missing???

Not trying to be a smart ass, but I think I explained it in my previous post. Ever hear of a Leslie speaker? When I play my Hammond through it, no one has to drive it around the hall to get a Doppler effect. It is a stationary speaker(s) that are routed through baffles that spin at various speeds. When you are directly in line with the opening in the baffle, the wavelength is shorter, when you hear it reflected off various hard surfaces in the room (as the baffle continues to spin) the wavelength travels farther to your ear. Hence a longer wavelength.

Wave length= frequency=pitch
Wave height=amplitude=volume

The Doppler effect has nothing to do with amplitude or balance in a stereo field. And it does not depend on speed or type of sound source. As the wavelength gets longer and shorter in relation to the listener due to his distance from the source, it actually remains the same at the source. The resultant phenomenon is a perceived rising and falling in pitch. Higher in close and lower as it moves away. There doesn't have to be a car that is generating the sound. The sound can come from a muffler or a speaker and it will make no difference. Why would you believe the sound source has to move and not merely the sound itself? Each speaker becomes the source in turn thereby moving the sound in space. This is not an illusion, it is happening.

This is an acoustic phenomenon more dependent of the resolution and timing of the playback system. The system in question seems to consist of a substantial number of speakers that I believe would yield enough resolution to produce the effect. I am only assuming that the sound is moving in sync with the lights as they circle the track. Of course if this assumption is incorrect, all bets are off afaic.

The sound does not have to travel 360 degrees. Have you ever heard a train pass? Or a siren? As to your stereo analogy, stereo is a two dimensional effect and has no relevance to this discussion.

Oh, and a midi file is merely a set of instructions and makes no sound of its own.

-e.

Thank you for your detailed response. I too am a musician, which is why I find this topic interesting.

Let's say the pitch of the Honda engine is 1000Hz, for arguments sake. Each speaker is outputting 1000Hz, but the perceived location of the source changes as it moves down the track, with each consecutive speaker putting out 1000Hz. The 1000Hz never changes, but the direction from which it emanates does. Therefore, no doppler, right? Whereas an actual moving sound source would make that 1000Hz sound like 1200Hz as it moves towards you and 800Hz as it moves away -- doppler.

The part I am having trouble with is your statement that the wavelength, or pitch, of a sound is dependent upon how close you are to the source. You state that when a wavelength has to travel farther to your ear it becomes longer, hence the pitch is lower. That doesn't sound right (pardon the pun). That would mean that people in the front row of a concert are hearing a song at a higher pitch than those in the back row. Is that true? I know that amplitude decreases as distance increases, but does pitch change also?

If so, then you are correct about the speakers on the track and there would be a true doppler effect.

onboard with senna suzuka 1989 - YouTube

seems no doppler with the onboard mike, but when the stationary mike is used at the end of the lap - doppler!
ta da!
Bill K

If

the thing that creates the sound

is not moving

Towards or away from you,

There is no doppler effect.

Case closed.


A "leslie speaker" has a (albeit minimal) doppler effect as the opening from whence the sound comes is moving towards you, and then away from you, and then towards you again, over and over.

Hi Ernie

Hey Jeremy!

I'm glad someone else sees them...

The speakers don't have to move. The sound is still moving away from you as it follows the light.

Stay away from the light.

Its the moving sound source which creates the effect.....not the sound itself......
Think of a fire hose on a moving fire truck blasting against an out of shape wall with big blocks missing, the water will disperse differently as it moves. If the hose isn't moving the reflection of the water won't change. If you move it 5 feet it'll have a different pattern, its the movement which creates the effect........just like Jeremy says :-)

What about this?