bass extension to 5Hz?

[weiss2496]

Hi all

I recently had a conversation with a chap who told me that one should build audio systems which can reproduce down to like 5Hz or so. This in order to reproduce the ambiance of the recorded venue. He says, when the frequency range is extended to 5Hz the "stage" expands to the limits of the recorded venue. Multichannel sound would seem artificial in comparison.
Does anybody have any experience in that respect?

Daniel

[Sounds Great]

How does he think he is going to reproduce 5 hz?

[GREENFENDR]

humans can't hear down 5HZ, but we can definatly feel 5HZ.

[weiss2496]

Originally Posted by Sounds Great

How does he think he is going to reproduce 5 hz?

He builds his own speakers which can do that. And takes care of the proper room treatment of course...
Daniel

[liuto]

You'll get all kinds of infrasonic noise like cars, trains, air conditioning etc. that you can't easily keep off. You just have to try this once with a good pair of real omnidirectional pressure microphones and you know what I mean. You should first find a room that blocks off this infrasonic noise, that you normally don't notice but will ruin your recordings.

Regards
Hermann

[Sounds Great]

Originally Posted by weiss2496

He builds his own speakers which can do that. And takes care of the proper room treatment of course...
Daniel

How does he do this? Companies that have been building speakers for decades can't build speakers that can do this.

[GYMusic]

Unless you're recording/playing back blue whales or a huge pipe organ it's pretty much a moot point.

[Tibbon]

Saw a setup at AES that claimed to be able to get to 4hz. Trying to remember who it was, but the speakers did sound damn good.

[larsfarm]

Originally Posted by GYMusic

Unless you're recording/playing back blue whales or a huge pipe organ it's pretty much a moot point.

It is interesting that in our equipment we insist on a frequency response that extends far beyond human perception on one end of the spectrum and gladly accept that our equipment neither reaches down to what our instruments produce or what we clearly can perceive on the other end of the spectrum. Why is that?

L

[zilver]

I think most rooms are too small to fit a 5 Hz wave..... Like cars with R&B music where you can only hear the bass outside the car.
Or doesn't it work that way ?

Hans

[Jim vanBergen]

I dunno, I have heard 10Hz with no problem, and have heard over 30kHz, believe it or not. Don't see why you can't "hear" 5Hz. My body sure interprets it, though you have to make sure you have a signal chain that can reproduce it! Most audio electronics have filter sets to try and exclude extreme LF like the square wave produced with power-on & shut down.

[Sounds Great]

Originally Posted by Jim vanBergen

I dunno, I have heard 10Hz with no problem, and have heard over 30kHz, believe it or not. Don't see why you can't "hear" 5Hz. My body sure interprets it, though you have to make sure you have a signal chain that can reproduce it! Most audio electronics have filter sets to try and exclude extreme LF like the square wave produced with power-on & shut down.

Are you sure? How do you know you "heard" 10 hz? And what makes you think you have heard over 30kz? No humans are known to hear that high.

[Jim vanBergen]

I can interpret sounds above and below 20-20. I'm sure you can, too...it may not be audible, but the pressure change is significant (as well all know, sound waves are simply a shift in pressure). I didn't think there was a whole lot below 20Hz until one of my professors --when I was getting my master's degree at Yale-- challenged me, and to prove him wrong I had use test gear to generate a signal path capable of going below and above the threshold of human hearing. A pure sine wave at 10Hz is pretty f'in loud with minimal amplification, and is a fundamental note (I think it's E flat; the lowest note on a piano A0 is around 27Hz FWIW) that requires a large space for a full period to occur. Getting large enough mass and excursion is not hard to reproduce; I used three 18" woofers and bastardized a series of off-the-shelf electronics to reproduce the signals. And yeah, after being exposed for a while it made my bowels queasy.

To replicate signals above 20kHz I used several pieces of B&K test gear from a reference lab that specifically dealt in measurement and calibration, and was the subject in what was like a standard hearing test- raising my hand to stimulus I "heard". In the case of HF, I can't name a "pitch" or note above 20k, as I interpreted the stuff above 20k as more like a harsh harmonics. These days I can only hear up to about 17.25k (my hearing damage is VERY specific and confirmed by my audiologist) in one ear and 18k in the other. 30K is pretty easy to interpret; it's the absolute consonance of 10k (a 1:3 harmonic ratio) and is out there, but if your brain ignores the overtone, all you interpret is the fundamental.

interesting sidenote: I grew up (being taught by my grandfather) tuning bronze bells by hand, and to insure a note's accuracy, the series of harmonics must be perfectly accurate. So I think I got used to listening to harmonics, and when they are present, I hear 'em, even if my brain is not using audio as the input source- does that make sense? But you don't have to be a 9th generation bellmaker to hear above 20k, even when you can't actually hear it! Your brain will tell you you hear it if you know what you are looking for.

Hope this helps!!

JvB

[jenkel16]

Jim, thank you for sharing that. That made my night. My instrument of choice is the bass and that is the reason why.

[Sounds Great]

This could help explain it.

Ultrasound

The upper frequency limit in humans (approximately 20 kHz) is caused by the middle ear, which acts as a low-pass filter. If ultrasound is fed directly into the skull bone and reaches the cochlea without passing through the middle ear, much higher frequencies can be heard. This effect is discussed in ultrasonic hearing. Carefully-designed scientific studies have been performed and confirmed what they call the hypersonic effect - that even without consciously hearing it, high-frequency sound can have a measurable effect on the mind.

Infrasound

Infrasound is sound with a frequency too low to be detected by the human ear. The study of such sound waves is sometimes referred to as infrasonics, covering sounds from the lower limit of human hearing (about 16 or 17 hertz) down to 0.001 hertz. This frequency range is the same one that seismographs use for monitoring earthquakes. Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation.

Test Your Hearing Range

Humans can generally hear sounds with frequencies between 20 Hz and 20,000 Hz (the audio range or hearing range) although this range varies significantly with age, occupational hearing damage, and gender. The majority of people can no longer hear 20,000 Hz by the time they are teenagers, and progressively lose the ability to hear higher frequencies as they get older.

[morebutter]

great topic... i remember reading in a GS thread recently that some church pipe organs can go down to 8hz...oh wait here it is:

pipe organ recording - dangerous at all volume levels!

[Sounds Great]

Originally Posted by morebutter

great topic... i remember reading in a GS thread recently that some church pipe organs can go down to 8hz...oh wait here it is:

pipe organ recording - dangerous at all volume levels!

Great thread!

[Jim vanBergen]

Nicely done with the resources, Sounds Great!

I do have to make one addition to my post- With the LF experiment-- untimately, my professor was right, and I was wrong- there IS a whole lot happening below 20Hz. It may be sympathetic vibration, but it affects us mentally and physically. My experiment proved without a doubt that my hypothesis was scientifilically incorrect, once I was in an environment capable of generating a complete sine period. But, as you can see...I have never forgotten that lesson, and the very real, quantitative, measurable frequencies below 20Hz.

Good stuff all around.


JvB

[matyas]

Depending on the nature of the sound, frequencies below 15 Hz or so may not be perceived as single events. I remember messing around with the oscillator on an old Buchla modular synth as an undergrad, and discovering that at very low frequencies, you would hear the periods of a square wave as individual thumps. As I turned up the frequency knob, the pulses started to meld together until they were fast enough to be heard as a definite pitch. Try recording a bass drum playing quintuplets at 60 beats minute (equivalent to 5 Hz). Double the speed digitally, and it will still sound like discrete drum hits. Speed it up 20 times, and it will sound like a single tone with a frequency of 100 Hz.

[klaukholm]

Originally Posted by zilver

I think most rooms are too small to fit a 5 Hz wave..... Like cars with R&B music where you can only hear the bass outside the car.
Or doesn't it work that way ?

Hans

The size of the room is irrellevant.

[larsfarm]

Originally Posted by klaukholm

The size of the room is irrellevant.

Indeed. Pressure can be high or low or vary even in tiny spaces and that's all there is. Wave length has nothing to do with that. It's all about pressure variations.

L

[Schaap]

Originally Posted by morebutter

great topic... i remember reading in a GS thread recently that some church pipe organs can go down to 8hz...oh wait here it is:

pipe organ recording - dangerous at all volume levels!

Some years ago I had a client with a pipe organ recording made somewhere here in the north in a large church and he asked me to prove that he had a decent 5 Hz pipe organ recording. He wanted to be in the Guiness Book of Records to have made the lowest pipe organ recording(?).
Problem was he didn't had the mic and preamp/recorder to record this properly. But we could identify another almost pure 10 Hz pipe organ tone without harmonics and at rather high volumes it was noticeable. Not that you could hear a low tone but it did something in your 'hearing. '

Henk

[zilver]

Originally Posted by klaukholm

The size of the room is irrellevant.

Thanks and sorry for being confused/confusing things.

Hans

[Sloiselle1]

Bag End came out with processing/speakers years ago using what they called ELF (extended low frequency) technology that they claimed was flat to 8Hz but I don't hear much about it nowadays. How much low end is enough? I took an acoustics class with Dave Moulton years ago and he demonstrated 30Hz. You had to move around the classroom because of the room modes but when you found it, you couldn't really hear anything, you just felt uncomfortable and kind of wanted it to stop!

As to hearing 10Hz, watch a clock with a second hand and tap your table 10 times every second - there you go. You can make it louder or use a different waveform but your still dealing with an event with a periodicity of 100ms.

I'm not suggesting we shouldn't have full range speakers but I wonder if there's anything else that could be considered instead that might improve the overall listening experience besides extending the bass so much.

Scott

[Tibbon]

Thanks for your posts Jim.
Jim is one of the guys on here that I really trust his ears and know that he's not going to just spit bullshit about stuff he doesn't really hear. If he's saying he heard something, then I'm likely to believe him.

The tapping the hands on the table 10 times in a second doesn't really do it, because that's causing a ton of high frequency noise to be played in there that will mask the tone.

The size of a room does matter to allow the wave room to actually develop. Getting it so that you can hear 10hz in a closet is a bit different than in a 200sq meter room.


It was pointed out to me at AES that going much lower with your monitoring can reveal some things that you wouldn't think of hearing otherwise, like someone trying to really slowly closing a door and the pressure on all the microphones changing just a bit. You aren't going to hear that on NS-10s

[Jim vanBergen]

Originally Posted by Tibbon

If he's saying he heard something, then I'm likely to believe him.

Thanks, Dave.
I should reiterate and perhaps clarify for any naysayers. The verb 'TO HEAR' is defined --and is explicity expressed as-- the ability to perceive sound vibrations and or sound pressure. When we actually 'hear' a 1k wave, hair on the cochlea is stimulated and the brain interprets that sensation. If you sense a 60Hz kick drum in your stomach, is that "hearing" it? When that signal is partially experienced by the inner ear and partially by the entire body, is it still 'heard'?

Perhaps when it is extreme LF we are actually feeling the sensation upon all of the body...but the brain interprets the sensation, either as pressure, or as a sonic experience depending upon your personal history of experience.

I have had clinically deaf patrons attend concerts and raves because they could "hear" the subs and dance all night to the beat. Whether or not anyone disagrees with the nomenclature "to hear" information below 20Hz, no one can claim it is not experienced or interpreted by the human body. It's very easy to reproduce subharmonic information lower that 20Hz. All that requires is the proper mass and excursion for a generated signal. Many days I will experience (or hear) subs being tested at 20Hz with the commercially available proper testing gear- a simple tone generator into a commercial amp & sub. It's easy to generate audio above and below the range of human hearing if you simply wish to do so with filtersets and a combined simple series of electronic and mechannical engineering changes to readily available pro audio devices.

Whew. I have not taught a class on psychoacoustics before.

regards to all...and I really love this thread!

JvB

[Sounds Great]

I thought the hearing part was in the ear. Below that I think you feel the sound waves. But that is also kind of contradictory as it is still called a sound wave.

[Jim vanBergen]

Well, the brain simply interprets a nerve impuse, and we interpret that as a sonic event. Remember that HF content is more easily discernable by direction, whereas LF content is less directional -- this is all due to how our receptors interpret the LF data.

[tenor39]

Originally Posted by Sloiselle1

Bag End came out with processing/speakers years ago using what they called ELF (extended low frequency) technology that they claimed was flat to 8Hz but I don't hear much about it nowadays.
Scott

The ELF was a system that put a large subwoofer in an enclosure that was too small for it and then equalized the response below the box resonance. In other words, all of the LF was generated below the system Fs, which in theory eliminated the speaker/box resonance as an obstacle to clean bass. The problem was that the "integrator" could only generate so much EQ before it bottomed out the cone of the driver. As a result it had a moveable HP filter to eliminate infrasonics. I toured the Bag End facility in IL and we played the Telarc 1812 Overture on their largest system, driven by a Crown Macro Reference amp (1K W RMS). It could not handle the SPL at all above a certain point and the integrator would slide up and cut off the LF to prevent bottoming. It sounded great at low SPL, but was not up to the task of producing realistic levels.

I'm with Jim about frequencies below the "audible" range. They do add weight and impact to sound, and I have done experiments in which we used single vs. stereo subs. The results were easily heard. The sense of "space" was drastically better with stereo subs (crossed over below 40Hz, too). Try listening to pipe organ on your best cans and then a really good speaker setup. The visceral impact is missing with headphones.

[mohthom]

There's a whole host of people I've come across who claim to 'hear' using the chest cavity. That's one of the reasons live concerts (primarily acoustic/orchestral) are so much more 'real' than the recordings - because there's none of that sub bass material to reproduce. Maybe that's another reason mixing on headphones is shunned (because there sure as hell is some nice headphones out there - better than NS10s anyhow).

MohThoM