What makes the noise, the fan or the air moving through it?

[SuprSi]

Hello,

I'm curious to know what, in the case of a chassis fan, makes the noise - the air moving through it or the fan motor? Currently, my rear case fan is the loudest fan in the machine, and I've seen these silent fans around the place but wasn't sure if it's worth the effort replacing it.

Cheers,

Simon.

 

[QTPie]

Let's sit down and think.

What if there's no fan, is there any noise?
If no, then the fan makes the noise.

Godamnit, it's the fan that makes the air moving fast which causes the noise!

 

[Mitzi]

<< Let's sit down and think.

What if there's no fan, is there any noise?
If no, then the fan makes the noise.

Godamnit, it's the fan that makes the air moving fast which causes the noise! >>



So the same fan in an airless environment would be silent?

 

[Sen]

<< So the same fan in an airless environment would be silent? >>



Anything in an airless environment ( vacuum ) would be silent.


As for the original question... I guess it's both. The type of fan ( sleeve or ball bearing )... and amount of air moving though it would contribute to the noise. Ah, I dunno...

 

[joohang]

The very sound you hear is the wave motion of air particles.

 

[QTPie]

<<Anything in an airless environment ( vacuum ) would be silent>>

Yes, that's true.

<<The very sound you hear is the wave motion of air particles>>

Air particles? Interesting!
Correct me if I'm wrong. It's been awhile.
Air is a quantity. The sound you hear caused by frictions when the fan hit the air and vice versa.
I hope someone who is good in Physics can help us here.

 

[SuprSi]

Heh, thanks for the replies folks. Certainly cleared things up

Si.

 

[Amused]

<< So the same fan in an airless environment would be silent? >>



There is no sound in a vacuum. Sound waves require a medium to travel in.

In other words, "In space, no one can hear you scream."

 

[Mitzi]

What if there's no fan, is there any noise?
If no, then the fan makes the noise.

To combine and sum up what everyone else has said...

If there's no air, there's no noise.

So its a combination of things which causes the noise -

The fans motor (may make a slight noise) but it requires the air as a medium to travel through so it can be heard, also the wave motion of air particles creates additional noise.

Edit : BTW - interesting question SuprSi!

 

[Legendary]

Apparently this question needs to be put into the "Highly Technical" forum

 

[RSMemphis]

<< Air particles? Interesting!
Correct me if I'm wrong. It's been awhile.
Air is a quantity. The sound you hear caused by frictions when the fan hit the air and vice versa.
I hope someone who is good in Physics can help us here. >>



Sound is caused by waves of increased and decreased pressure of the air - or water, or metal or wood, or whatever.