# Dampening Air Pressure Peaks

1. Oct 26, 2007

### kach22i

Attached is an image of four simple systems, two are loudspeakers, two are air fans.

My goal here is to examine if any of these "boxes" do anything to lower the peak amplitude of the energy in the system and which does it better and why.

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Q1: Imagine the loudspeaker generates a real low and then a real high frequency sound pressure wave.

1a. Which box muffles/dampens/attentuates the extremes better?

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Q2: Imagine the fan varies it's speed to generate real low and then a real high air flows which then result in low and high pressure waves.

2a. Which box muffles/dampens/attentuates the extremes better?

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#### Attached Files:

• ###### Heave-Drawing.jpg
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2. Oct 26, 2007

### ank_gl

silencer does the same thing for the engine

3. Oct 26, 2007

### kach22i

Yes, an automobile engine produces noise and the flow of hot gases, so a muffler is an excellent comparison.

As mufflers vary from the straight flow-through type typicaly found on aircraft to the more restrictive type designed to provide a measured level of back-pressure for proper operating, there is a lot to choose from.

Looking again at the four diagrams, if we were rate them from least restrictive to most restrictive from a "pressure" stand point and then rate them in order of lowering the "amplitude" (sound and or pressure) would they be in the same order every time?

Which one first?

Which one last?

Why?

4. Dec 3, 2007

### what-how-why

Suppose you cannot compare the sound energy and pressure energy in the four mechanicl boxes at all.
In case of the pressure energy of air pumped by fan, if there is a peak of pressrue from the fan, the air inside the box absorbes the addtiional energy by increasing the pressure which is to be released again later. In case of sound energy, if there is a peak of sound energy from the speaker, I do not see any media in the box that can absorbe the additional energy and release it again later.