Why are some rpms louder than others?
07-19-2006, 09:55 PM
#1
Why are some rpms louder than others? I have been running with the cutout open for the last couple of days, and it seems that at some rpms are louder than others. At 1100 it is very quiet. at 1800 it is fairly loud and it seems at 2500 and higher it gets quieter. Why is this?
07-19-2006, 10:06 PM
#2
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Originally Posted by prince xizor
I have been running with the cutout open for the last couple of days, and it seems that at some rpms are louder than others. At 1100 it is very quiet. at 1800 it is fairly loud and it seems at 2500 and higher it gets quieter. Why is this?
Certain RPMs simply resonate inside the car more, especially since the cutout is right under the car and doesn't exit out the back like your tailpipes would.
07-20-2006, 12:39 AM
#3
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exactly. drone is a certain frequency that, when exposed to the right acoustic environment, somehow magnifies/amplifies into an annoying HMMMMMMMMMMMMMMMMMMMMMMMMMMMMM that you can pretty much feel.
btw, cutouts FTW.
btw, cutouts FTW.
07-20-2006, 01:09 AM
#4
Originally Posted by 3VstangGT
exactly. drone is a certain frequency that, when exposed to the right acoustic environment, somehow magnifies/amplifies into an annoying HMMMMMMMMMMMMMMMMMMMMMMMMMMMMM that you can pretty much feel.
btw, cutouts FTW.
btw, cutouts FTW.
Reminds me of Crash Test Dummies - Mmm Mmm Mmm Mmm. That song rocks.
Resonation is a pretty amazing thing. Every object has a "natural frequency" that it vibrates at. Rubbing your finger along the rim of a glass hits this and causes the noticeable sound you hear if you do it right.
Maby the most well known victim of resonation is the Tacoma Narrows Bridge. Do a video search for it and you'll see what I mean.
07-20-2006, 10:05 AM
#5
Originally Posted by TheBlurLS1
Resonation is a pretty amazing thing. Every object has a "natural frequency" that it vibrates at. Rubbing your finger along the rim of a glass hits this and causes the noticeable sound you hear if you do it right.
07-20-2006, 10:10 AM
#6
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Originally Posted by TheBlurLS1
Maby the most well known victim of resonation is the Tacoma Narrows Bridge. Do a video search for it and you'll see what I mean.
natural frequency is why some buildings fall during an earthquake and some do not. when an earthquake hits a building's natural frequency, say bye-be.
i remember there was once an earthquake in a certain city and all buildings of roughly the same specific height/stories fell and no others did. i know it's not too detailed, but it's a great example of natural frequency and resonance.
07-20-2006, 08:24 PM
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Originally Posted by prince xizor
So like adding water to the glass to produce a higher tone, what can be done to change when the drone or resonance occurs?
The resonant frequency of something (like your car) is based on the physical size/shape of the object.
To change the frequency at which something resonates, you have to change the physical dimensions.
Sort of like your example above, but thinking of a bottle of water and you blow across the opening to make it "whistle". If you pour water out, the tone changes (gets lower). You have changed the physical size (or in this case volume) of the chamber of air and thus changing the frequency.
