Octaves question

[JBL 4645]

Looking a site that tells there are 10 octaves fine. What is the octave between 0Hz and 20Hz 0 octave?

http://www.easyeartraining.com/2010/04/20/frequency-band-characteristics-part-1/

[Baron030]

Below octave zero, there appears to be a double zero octave.
www.drewdaniels.com/FREQ.pdf (http://www.drewdaniels.com/FREQ.pdf)

Baron030:)

[boputnam]

What is the octave between 0Hz and 20Hz?If you can't hear it, is it an octave? :p

[brad347]

If you can't hear it, is it an octave? :p

If we're talking pure sine tones, Siegfried Linkwitz would probably say "no." :)

[brad347]

I read a pretty interesting thing by Linkwitz the other day. He says that if a tree falls in the forest and there is nobody there to hear it, it doesn't make a sound-- it makes heat.

The idea is that sound is perceptual-- it is what is created in our minds when energy in the form of compressed or rarefied air acts upon our ears.

If there is no ear there to hear it, the energy just bashes into other objects in the forest where it is dissipated in the form of heat.

However, taking this thought experiment further, a low frequency oscillation below 20 cycles, in the form of a square or sawtooth wave, COULD be heard by the ear--just not as a 'tone.' We'd hear it as a series of impulses.

I was messing around with subtractive synthesis one day, and found that if I set up a square wave at frequencies below 20 Hz, I could hear the oscillation as a series of "clicks." If I took the modulation wheel and sped it up, eventually the clicks would meld together as a square wave 'tone' with all of the harmonics of a square wave. The transition point reminded me of an idling motorcycle engine revving.

What's interesting is that harmony and rhythm are the same thing-- harmony is just speeded-up polyrhythm. If I dialed up two low-frequency oscillators to produce clicks in low-prime ratio polyrhythms, they would produce a harmonically consonant tone. For example, the classic "3 over 2" polyrhythm, like a triplet in duple meter, when speeded up produces an interval of a just-tuned perfect fifth. 5-over-4 speeded up produces a just-tuned major third. 2:1 is an octave.

Kind of interesting how our brain processes sound. Past a certain point it stops hearing "polyrhythm" and starts hearing "harmony," and this happens around 20 Hz. It's like our brain stops being able to track impulses and starts tracking tones instead.

[JBL 4645]

If you can't hear it, is it an octave? :p

:confused:

You lost me.




I read a pretty interesting thing by Linkwitz the other day. He says that if a tree falls in the forest and there is nobody there to hear it, it doesn't make a sound-- it makes heat.

Kind of interesting how our brain processes sound. Past a certain point it stops hearing "polyrhythm" and starts hearing "harmony," and this happens around 20 Hz. It's like our brain stops being able to track impulses and starts tracking tones instead.

Well maybe that is where the body starts to sense vibrations if, sat next to it or on top of it? A bus vibration wow that rattles down low, but how far down, I've had the opportunity to have portable pc laptop and run spectrumlab with an calibration microphone to see how far down and get an idea on which frequencies generate the 90db to 100db?

I've used an SPL db meter but that only tells me the SPL not much else though. I can guess tones like 30Hz to 200Hz with in the engine sound. Who knows most likely (very likely 20Hz and below).

I've also read something years ago that sub bass can produce heat? Now that is the crazy thing I've ever read. Guess i can use it to radiate out warm lows during the wintertime. :D

[brad347]

sound is energy. If the compressing and rarefying air particles hit something that stops their movement, that energy--like most energy-- is usually dissipated as heat. Usually it's tiny tiny amounts of heat, though.

[JBL 4645]

sound is energy. If the compressing and rarefying air particles hit something that stops their movement, that energy--like most energy-- is usually dissipated as heat. Usually it's tiny tiny amounts of heat, though.

Oh, I see so it’s not much to worry about then. Does it, matter what SPL db it is, or frequency?
Interesting learn something new each day.

Bugger I’m coming down with cold. I haven’t had one in two years now.:(

[Allanvh5150]

Hi Ash,

If you are talking the 10 octaves between 20hz and 20khz, there are also 10+ octaves below 20 hz and depending on who is listening, there are a few more above 20khz as well. An Octave is a doubling or halving of a frequency but no one really listens below 20 hz except fot Elepphants and Whales.

Allan.

[eso]

There are tones that can be perceived as musical below 20Hz, and certainly perceived in a visceral manner below 10Hz.

I borrowed a "Bass Mechanic" auto sound set-up disc when I first commissioned my bass horns in my listening room. One of the bands on the disc is a slow sweep from 0-100 Hz. This is for identifying rattles and resonances. Because a hyperbolic horn couples a driver to a room far more efficiently than a cone in a box flapping in free space, output below the flare rate of the horn is still likely to be considerably louder than the same driver in a box. With the slow sweep the room would start seriously throbbing at about 8Hz, and the chest and lungs feel quite strange under those conditions. By 15 Hz a tone is clearly audible, increasing in volume as it sweeps into the real horn loading.

These are 30Hz horns built into the pitched spaces under the roof, made with lathe and cement/stucco. The last 3 feet of the horns expands an extra amount to compensate for the volume of my 3-way horn mains. The design uses the floor and ceiling as a continuation of the horns. The listener is effectively sitting inside the horns, not unlike the coupling Steve Schell did with his original Big Bottom sub.

Now, whether your low frequency drivers are up to this sort of bass reproduction is another thing altogether.



eso

[brad347]

That's interesting.

The 20-20kHz thing is probably just used because it's a "neat" set of numbers. In the real world, humans probably have variable ranges of hearing, as we have variable ranges of almost everything else.

I don't find it strange that some people might be able to hear a tone at 15 cycles. Many adults cannot hear above 15k. I can get up to about 17k myself before things pretty much drop off into oblivion (I'm 29). My wife has 16k and that's about it. My dad is lucky to have 10k on a good day (his hearing is going).

[JBL 4645]

Hi Ash,

If you are talking the 10 octaves between 20hz and 20khz, there are also 10+ octaves below 20 hz and depending on who is listening, there are a few more above 20khz as well. An Octave is a doubling or halving of a frequency but no one really listens below 20 hz except fot Elepphants and Whales.

Allan.

Cheers Al

That makes sense! Kinder like my cat hey, can listen to how many Octaves above 20KHz what? 6 Octaves?

Hows the weather down under.:)

This total damn ass video made me laugh. Its only suited for dog cats and bats! Not for human consumption.

http://www.youtube.com/watch?v=c6D3zRVSzp8

[brad347]

Hi Ash,

If you are talking the 10 octaves between 20hz and 20khz, there are also 10+ octaves below 20 hz and depending on who is listening.

10 octaves below 20 Hz sounds odd to me. Just thinking about it,

10-20 Hz would be one sub-octave.
5-10 would be another
2.5-5 would be another.
1.25-2.5
0.625-1.25

At that point we're looking at one compression and rarefaction every 2 seconds or more. It seems odd that there's any living thing that would perceive that as a "tone." More like a "gentle breeze!" But I've been wrong before.

[JBL 4645]

That's interesting.

The 20-20kHz thing is probably just used because it's a "neat" set of numbers. In the real world, humans probably have variable ranges of hearing, as we have variable ranges of almost everything else.

I don't find it strange that some people might be able to hear a tone at 15 cycles. Many adults cannot hear above 15k. I can get up to about 17k myself before things pretty much drop off into oblivion (I'm 29). My wife has 16k and that's about it. My dad is lucky to have 10k on a good day (his hearing is going).

What SPL db range are you pushing to hear that tone? What JBL or other do you have what is there frequency response range and sensitivity, what type of HF are they?

I can only manage 16KHz (and the tone as this) kinder pinching on the ear effect.
I’m worried about pushing the JBL control 5, tweeters any further in case of voice coil burn out. Then again the top end has some audio limiting.

Females have an edge over males (not to be sexist mind you) :p just an edge in their hearing range, unless they care to listen quality music/films or other?

[JBL 4645]

10 octaves below 20 Hz sounds odd to me. Just thinking about it,

10-20 Hz would be one sub-octave.
5-10 would be another
2.5-5 would be another.
1.25-2.5
0.625-1.25

At that point we're looking at one compression and rarefaction every 2 seconds or more. It seems odd that there's any living thing that would perceive that as a "tone." More like a "gentle breeze!" But I've been wrong before.

Yeah I see it. What kinder like wind? But do I hear it or only perceive it as feeling!

Yeah I guess 20Hz to 20KHz is fine for me unless I'm whale of course.:p

[JBL 4645]

Bugger I’m coming down with cold. I haven’t had one in two years now.:(

Wow that is the shortest cold I’ve ever had! Looks like a good 12 hours sleep and blowing the nose to flush it out, and plenty of Cream Soda did the trick.

[Ruediger]

Looking a site that tells there are 10 octaves fine. What is the octave between 0Hz and 20Hz 0 octave?

http://www.easyeartraining.com/2010/04/20/frequency-band-characteristics-part-1/

"An octave higher" means the frequency of a tone is doubled, "an octave lower" means the frequency of a toned is halved.

There is an unlimited number of octaves. There is no defined numbering scheme. You can define an octave to start at any frequeny.

If You like to define an octave starting at 17.64 Hz, do it. It extends to 17.64 Hz * 2 which is 35.28 Hz. If You want it to be "octave number 5" in Your scheme that's fine.

The octave below 20 Hz starts at 10 Hz, the octave below that starts at 5 Hz, etc.

Ruediger

[toddalin]

Looking a site that tells there are 10 octaves fine. What is the octave between 0Hz and 20Hz 0 octave?

http://www.easyeartraining.com/2010/04/20/frequency-band-characteristics-part-1/


No, you are misquoting the site. The site specifically notes that there are 10 octaves that humans can hear. This is what it says:

Now comes the time that we need to address actual characteristics of different frequencies, as well as the different octaves that humans can hear. (As in, how many are there actually?)

[jcrobso]

The lowest note on a piano is 27hz or low A, there are some pianos that have 3 extra notes that take you down to a F or 20Hz. A BIG pipe organ with a 32' stop can get to 16Hz.
If you talking a musical octave then you can use note names like C,D,E etc.

In crossovers we talk about 12db per octave below and above the desired crossover frequency. This has nothing to do any musical notes!
http://www.intmath.com/Trigonometric-graphs/music.php