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[Jonathan Johnson]

If you ever left one window open on the highway, you've heard 5hz sound, or whatever the fundamental frequency is of the organ pipe you're driving.

I think I've heard what you are referring to when I open the sunroof on my '12 Honda Accord.

But is that really a 5Hz sine wave I'm hearing, or is it a 5Hz amplitude modulated beat frequency of white noise in a higher frequency band?

[Steve M Smith]

In a vacuum or outside in free air?  Air absorption of High frequency content is a real thing

No sound will travel in a vacuum!


Steve.

[Johannes Halvorsen]

No sound will travel in a vacuum!


Steve.

This is just plain wrong! I know for a fact that laser canons goes Phew! Phew! Phew! in space.

Jeez... How stupid are people these days...?

[Jonathan Johnson]

Sound can't travel in a vacuum unless it's the kind that sucks dirt from the floor.

But does it check its bags or carry-on?

[Ivan Beaver]

I have a hard time understanding the statement, speaker is notorious at producing distortion. I don't know there is such a speaker exist...Could you elaborate it?

It depends on how loud the distortion is and how loud it is in relation to the fundamental.

Here is how to do a simple test.  Use a sine wave generator and start around 60Hz or so and turn up the level to a decent SPL.

Now start to lower the freq-without changing the level (assuming the generator has a constant voltage output)

At some point you will hear the freq go up while you are lowering the freq.

This is point at which the distortion is much greater than the fundamental.

The fundamental is still there, but you can't hear it because of the distortion (higher freq) present.

There is one manufacturer that makes claims about being able to go really low.  But at an octave or more ABOVE the low freq in the spec-the distortion is FAR greater in SPL than the fundamental.

So yes it CAN reproduce those freq, but not at any level that is useable.

They even say so in a little hidden area of the website.

But IN REALITY-EVERY speaker ever made can easily reproduce 1Hz, even little tweeters.

Now whether or not you can hear it is a COMPLETELY different story.

And yes-there are plenty of speakers that can reproduce 20Hz at plenty of level so you can hear it clearly.  It does not really need to be that loud either.

But most people have simply not heard these speakers, so therefore they say it can't be done.  But they are wrong.

You can easily hear down quite lower than 20Hz-AS LONG AS the signal reproducer is still clean.

[Keith Broughton]

Some inetersting info...
http://www.soundandvision.com/content/way-down-deep-ii-servodrive-contrabass#gtYRDtWMpWum8ov4.97

[David Allred]

You are all missing the point.  High frequency wave forms are closer together than low ones.  That means that more waves are packed into the same space.  Therefore, high frequencies are heavier, and gravity pulls them down into the ground at a shorter distance than the lighter low frequencies.
On larger systems this is combatted by setting high diver really high above the main system (like maybe 200 ft) so the high frequencies hit the ground further back where the lows also hit.

[Ivan Beaver]

You are all missing the point.  High frequency wave forms are closer together than low ones.  That means that more waves are packed into the same space.  Therefore, high frequencies are heavier, and gravity pulls them down into the ground at a shorter distance than the lighter low frequencies.
On larger systems this is combatted by setting high diver really high above the main system (like maybe 200 ft) so the high frequencies hit the ground further back where the lows also hit.

Except for the fact that the highs are often refracted upwards away from the people-especially during the day when the ground is warm.

Maybe (tongue in cheek here) the reason they "float away" is because they are smaller and don't have the "density" of the lower freq.------------------

[David Allred]

Maybe (tongue in cheek here) the reason they "float away" is because they are smaller and don't have the "density" of the lower freq.------------------

That is why on Mars, all systems sound better, and on Venus they sound worse.

[Speed Daemon]

Hello,
My partner said
1. Low frequency (20Hz) sound travel further than high frequency (20kHz). I disagree.
2. Human could hear 20Hz. I disagree.

Thanks, Have a nice Thanksgiving!

A1:  Why not?  Since you didn't state any particular propagation mode, my answer is that an acoustic Watt is an acoustic Watt.  All other things being equal, so will the distance that they can travel.  And if all things are not equal, then it's not really about the frequency.  I have noted that you said "travel" and not anything about relative attenuation, obfuscation by ambient sounds or other possible factors.  If you want to spring for a very long length of rigid pipe, I'd be happy to demonstrate this.

A2:  I can hear a 20Hz sound just fine.  The only limiting factor here is access to a source of a slightly flat E₀ note.  A cathedral organ or a Moog Taurus (a plain old function generator will do in a pinch) with the appropriate loudspeaker will produce the note--see for yourself.  While you may feel low bass with your viscera as well as with your ears, you can easily check by covering and then uncovering your ears.

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