All this "acoustics" nonsense...
- Thread starter technominds
- Start date
RICK FITZPATRICK
New member
Dang, you let my secret out. Ok, I'll admit it guys. I'm a midi "newb". Got a ton of midi related stuff to figure out and no time to do it. As usual. geeeezus, I'm still trying to finish hooking up stuff I've had for years and never even plugged in before they became obsolete
. Too many irons in the fire and responsibilitys I never wanted. Anyway, thanks Mike My Irish temperment gets the best of me sometimes Which translates into verbose bla bla bla.thanks Supercreep. I owe ya one.
(and not in the cave. )
didgijimmy
vexed
I agree with what Fitz and many of you have said, but I still see some usefullness to this idea. it may not work well for micing (though I don't see any reason it wouldn't for close micing), but Imagine:
It's Midnight, the kids are asleep, the wifes asleep, parents, or whatever. Youve got neighbors in the apartment next to you, but you go to your favorite 15W+ tube amp and crank it till your deaf and play all night long. No one would hear it but you. Ladies and gentlemen, I have a dream.
It's Midnight, the kids are asleep, the wifes asleep, parents, or whatever. Youve got neighbors in the apartment next to you, but you go to your favorite 15W+ tube amp and crank it till your deaf and play all night long. No one would hear it but you. Ladies and gentlemen, I have a dream.
rayc
retroreprobate
Doesn't the beam go to and beyond you with your cranked amp?
If the beam creates sound waves along it's length or even at it's focus won't these waves at least ripple or bleed a little?
I imagine this could also be anoying in the IR headphone way of moving from the focus & missing the signal - don't rock out, don't nod, don't move.
Good points made all over. I guess I'm just a cynic.
If the beam creates sound waves along it's length or even at it's focus won't these waves at least ripple or bleed a little?
I imagine this could also be anoying in the IR headphone way of moving from the focus & missing the signal - don't rock out, don't nod, don't move.
Good points made all over. I guess I'm just a cynic.
technominds
New member
Head tracking is another great technology you can see over at ted.com
.. but seriously, with head tracking you could have a system track multiple people in the room as well as the guy in the chair, and you would all hear the same thing!
didgijimmy
vexed
Man can't a brotha dream? Tha'ts a good point though. Imagine a person's reaction if I have an amp pointed out my window and they walk through the "beam" of sound. Seems pretty funny to me. I suppose once the sound hits the walls it's going to reverberate, so you may be right. But it would be cool.
RICK FITZPATRICK
New member
Are you suggesting driving this device with a guitar amp?Hmmm, unless its only "tube", electronic "distortion", or amp/speaker simulation that makes it sound like a typical small amp/speaker cranked to 10, I don't think this device would act as a small amp "speaker". Although, I can see your point. Kinda like trying to make this device sound like a Marshall speaker on 1 or 10...it ain't gonna do it.
I don't think it works like that. I didn't really understand the EXACT principle(and he probably wouldn't tell you the whole ball of wax because of their patents) but he did elude to the fact that the device uses a focused beam of ultrasound, which is NON LINEAR(whatever that means
) and the "sound" is produced right at your ear drums...which I thought was exactly how ALL "sound" works..ie(there is no such thing as SOUND!...think about it......sound is actually in your BRAIN....as a representation of the electrical signals sent via your ear drum(diaphram) moving in response to molecular movement of AIR molecules at frequencys produced by the SOURCE.Which actually brings up something I've thought about at length, researched, asked about on acoustics forums and discussed with friends. Everyone that I try to describe what I'm wondering about, can't seem to understand what I am saying. Maybe one of you can explain it. Here is the idea.
The whole crux of the subject in question has to do with "hearing" sounds that are DISTANT vs sounds produced in the same room, or even close to you outdoors. WHAT is it that tells you the sound is DISTANT.
..vs MOVEMENT...vs LOCATION vs AMPLITUDE vs other attributes of "sound"(doesn't matter about frequency/timbre/type etc.)..only distance.Its like this. I live just outside Coos Bay Oregon. My house sits up on the side of series of hills, that rise on each side of a 5 mile long "slough"..which is kind of like a river. Hiway 101 and a railroad track meanders parallel and along the edge of this slough, and is about a quarter of mile straight down the hill from my house. I can see the hills on the other side of the slough. These hills form a valley with the hiway and slough at the bottom of this valley. What is unique, is this valley acts like a giant echo chamber.
I hear lots of different sounds in the valley. Cars, trucks, trains/whistles, ships/boats, and sometimes(which I NEVER see cause they only fly over Coos bay when its overcast
...military JETS, which are the LOUDEST jets I have ever heard. There is even a gravel/stone company right at the bottom of a hill, with a HUGE stone grinder, that is the most obnoxious and loud machine I've ever heard...except for PILE DRIVERS!...OR bad musicians.
And once in a great while, we have THUNDER storms, that absolutely rock the whole valley. When the thunder cracks, anywhere within about a 5-10 mile radius, the echo train lasts upwards of a 15 to 20 seconds through the valley. Its absolutely HORENDOUS..Same with the JETS. These damn military pilots, fly so low, it makes the windows rattle. They circle the whole Coos Bay area..round and round for about a half hour. Unbelievable. Sometimes it sounds like one(although with the echos its hard to tell sometimes), and sometimes its definetly two or three. Usually about a mile apart..although, again its hard to say because I NEVER can see them, and the echo/reverb in the valley makes it hard to decern. Whats really wierd about these jets, is sometimes, they STOP overhead, and remain there for 5 to 10 minutes..moving ever so slightly in a circle about a quarer mile diameter. Its unbelievable. I was so bad one night last year, I actally called the Sherrif, the local TV channel, the mayor, AND, the next morning..the FAA. Of course, you can guess what they all said.
The local TV station person actally had the audacity to suggest I was imagining the sounds. Which is really wierd, cause the station is less than a mile from my house and they HAD to hear these jets. Hmmm,....Anyway, getting back to the subject at hand..
,..one night, as I was laying in bed, I was listening to a truck on the hiway down the hill. Now, here I am in bed, and the only way I could hear these sounds is via STRUCTURAL TRANSMISSION through the walls/windows. Yet, I could practically tell where this truck was on its way into Coos Bay. In fact, it stopped at a TRUCK WASHING station, about a half mile from my house, along 101. However, the driver left the truck running. For about an hour. It wasn't very loud, but given it was continuous(like the roar of traffic on a distant freeway) there were no "impact" or other types of sounds that would echo, nor was there movement. As I was listening, I noticed that one of my ears was totally deaf(at the time I had "impacted ear wax"..now removed). What struck me as unusual, was I could still tell this sound was distant..to the point I could almost precisely point to exactly where this truck was, even though, because of trees and homes, I couldn't really see it. Almost everyone has explained to me that because of "arrival time" differentials between the two ears, the mind can "locate" the source of sounds. With reason of course.
But there is the odd condition. I could tell this sound was distant, how far it was, locate it, and "hear" this sound as...DISTANT.
vs..my wife speaking softly to me from a foot away. Even indoors, and with one ear plugged up. The more I thought about it, the more curious I became. Heres what confuses me. When a "moving" molecular wave front in air, such as an impact sound, strikes the ear drums, it arrives at the left and right ear diaphrams, at different times. Actually the time differential is so slight it becomes amazingly clear how fast the two sides of our brain "interpret" these "stimuli" as "sound", analyzes it, identifys the time differential, the frequency/ amplitude/timbre (etc)at both ears, sends a signal to another part of the brain for analysis whether or not it is threatening, enjoyable, obnoxious etc, and then responds accordingly...like a loud unsuspecting noise makes you jump
. Ok, lets look at this "stimuli"...in this case, a "continuous" occilation of molecular level air molecules, moving back and forth at a particular frequency, right against your ear drum. I've read that a human being, because of the logrhythmical nature of the eardrum/anvil response, can detect the vibration of a SINGLE molecule against your eardrum, reacting only by shear response to your heartbeat moving the air, which has been proven in an Anechoic chamber, where the ONLY sound being produced IS the heartbeat.
What this tells me is this..your brain only detects the movement of air molecules, RIGHT AGAINST THE EAR DRUM. And if this is true, then WHY..do we hear sound that is DISTANT AS A DISTANT SOUND. Think about it. Close your eyes and listen to a distant sound. You "hear" that sound EXACTLY WHERE that sound is...NOT AGAINST your eardrum. Even though the sound may strike your eardrum much later(speed of sound) than when the sound was produced at the source, you still "hear" it as a DISTANT SOUND. Its like this.
Go into a dense forest, when there is fairly deep snow on the forest floor. Scream or yell, or have somebody about 100 or two hundred feet away yell. The snow and dense forest ABSORBS most if not all reflections, and actually absorbs a lot of the direct sound, making the amplitude less than if there were no snow. So things such as reflections reduce that which allows your two ears to "locate" the sound source. YET...you can still hear the sound as...DISTANT
Or out on a flat desert floor where there are no mountains if you can. I have done numerous observations over time in lots of environments. And without fail, you always hear a distant sound at its LOCATION, not at your ear, even though molecular movement is what is moving the ear drum...AT THE EAR DRUM....makes no difference...1 foot, 20 feet, 100 feetl, a mile...you always hear the sound WHERE IT OCCURS..not right at your ear. So why is that?
Whats even wierder...say you could ..like the truck, make a recording of the sound source at 1 meter away. Analyze its SPL. Now, reproduce that sound in a speaker..but NOW, PRECISELY reduce its amplitude to that which the sound would decay at 1 mile away, and play it back 1 meter from your ear with your eyes closed. You will "hear" this sound..1 meter away...not as if it were a sound source 1 MILE away. Now play it back SIMULTANEOUSLY, from the exact line of site direction as the sound source, at the same time the sound is arriving from 1 mile away. They will be IDENTICAL in amplitude. Yet, you will detect "something" different between the two sources...DISTANCE.So, when the gentleman in the video referred to "sound" being produced right at the ear drum....something tells me there is something wierd going on. Maybe I just don't understand all the dynamics at play here...but SOMETHING is going on.
Sorry for the long explanation.
fitZ
didgijimmy
vexed
Fitz, thats a pretty cool idea. I'll admit that I have absolutely no idea what is at play there. Forgive me if I am wrong, you may know more, but I know Muttley is well versed in acoustics and teaches classes on it. Would he know? You may want to PM him about it if he would know.
Also, if you haven't checked it out, I'd recommend the book: This Is Your Brain On Music. It's an excellent read and covers all forms of effects music has on your brain and such. You seem like you would enjoy it as much as I did.
By the way, the location of your house sounds incredible. At least the way I pictured it from your description. Must have beautiful vantage points. And where I used to live, we were up on a large hill with a huge valley than ran in front of us normally filled with corn. We had two large gulleys on each side and then woods behind us. Cars, ATVs, Motorcycles, they all drove us crazy. And your right, you haven't heard thunder until you lived at our house.
I remember when I was very young, and I lived almost across the street actually in the valley. My stepfather brought home a 3 foot wide pipe from his job and we would roll around in it and push each other and such. I was in that thing one day when some military jets flew by and I don't know if they were circling, but they would be deafening for 3 minutes at a time (an often occurance). Being inside that pipe one day it was so loud and I was so scared it brought me to tears and my mother had to come get me. I was probably about 5. Anyway, I can relate to what your talking about
If you find an answer to your mystery I would be interested in hearing it.
James
Also, if you haven't checked it out, I'd recommend the book: This Is Your Brain On Music. It's an excellent read and covers all forms of effects music has on your brain and such. You seem like you would enjoy it as much as I did.
By the way, the location of your house sounds incredible. At least the way I pictured it from your description. Must have beautiful vantage points. And where I used to live, we were up on a large hill with a huge valley than ran in front of us normally filled with corn. We had two large gulleys on each side and then woods behind us. Cars, ATVs, Motorcycles, they all drove us crazy. And your right, you haven't heard thunder until you lived at our house.
I remember when I was very young, and I lived almost across the street actually in the valley. My stepfather brought home a 3 foot wide pipe from his job and we would roll around in it and push each other and such. I was in that thing one day when some military jets flew by and I don't know if they were circling, but they would be deafening for 3 minutes at a time (an often occurance). Being inside that pipe one day it was so loud and I was so scared it brought me to tears and my mother had to come get me. I was probably about 5. Anyway, I can relate to what your talking about
If you find an answer to your mystery I would be interested in hearing it.
James
Its the reflections. I know you listed a couple examples of how it couldn't be.. but trust me, it is. Sound can also travel up into the air and back down again (if the air above is increasingly warmer with height). Its the same principle as light refraction between a layer of air and a layer of a denser material (such is shown on the album cover of Pink Floyd's Dark Side of the Moon).
I've read a couple of different theories on how we determine direction. Some say its due to a phase difference, some say its a difference in amplitude. I've read something about how the left and right ears process sounds differently. All theories require two ears though. I had a lecturer who was deaf in 1 ear, and wasn't able to distinguish where sound sources originated.
When you had 1 ear blocked but were still able to determine where that truck was.. it may have been due a familiarity of the area. Or maybe sound was traveling through your skull and you could still faintly pick up sound out of the blocked ear.
This has to do with the lack of reflections. At the end he said he had a cool sound of a coke can being opened. If he was to play that sound through a normal loudspeaker, you'd get a whole bunch of reflections and you'd be surrounded by the sound. With his device there are no (or minimal) reflections. Essentially, the sound would be exactly the same if you were standing 1 foot away as opposed to 100 feet. You'd perceive the coke can being opened right next to your ear.
RICK FITZPATRICK
New member
Trust you? Why should I
You offer no proof.This STILL doesn't tell me why I hear a sound source thats 100 feet away...at the source with reduced amplitude. NOT AT MY EAR.
Are you saying if there were no reflections it would sound like it was rignt next to my ear...only at reduced amplitude.
Something sounds fishy about that. What about in an anachoic chamber. Would a sound source from across the room sound like it was in my ear.? No matter the theorys...something still is wierd about this. Here is a good example that just happened. I'm upstairs with the door closed. Somebody just slammed a cabinet door shut. I hear the sound DOWNSTAIRS...not coming from the wall or door...where it would SEEM to have to have come from...simply by structural transmission...no reflections reach me from outside the room...yet I hear the slam as a DISTANT sound. hmmmmm...
I bet he could tell distant sounds were distant even though he couldn't locate them.
DrJosh
New member
So, when the gentleman in the video referred to "sound" being produced right at the ear drum....something tells me there is something wierd going on. Maybe I just don't understand all the dynamics at play here...but SOMETHING is going on.
I think I can offer some insight here, since I work in nonlinear focused ultrasound.
When the presenter mentions sound being produced right at your ear, he means that different frequencies are being produced. Actually frequency generation occurs at each point in the sound beam radiating from his panel (a phased transducer array), if the amplitude is sufficiently high (high enough to generate nonlinear effects--about 190 dB in air).
There are two ways of thinking about nonlinear sound propagation: in time and frequency. From the time perspective, consider a sinusoidal pressure variation. If the amplitude is high enough, the increased pressure at the peaks of the sinusoid result in increased density, which results in increased sound speed. The opposite is true for the reduced pressure in the troughs of the sinusoid--sound goes slower there. So you have peaks going faster than troughs which results in waveform distortion. Eventually the sinusoid evolves into a sawtooth wave, like this: |\|\ The discontinuities are called shocks, they're essentially little sonic booms.
In frequency one considers harmonic generation. If a sound wave at frequency f is propagating at sufficiently high amplitude, the wave interacts with itself in such a way that some of its energy is transferred to a new second harmonic at 2*f. Then 2*f interacts with itself to produce 4*f, and 2*f interacts with f to produce 3*f. Etc, etc. As the sound propagates it continues to generate higher harmonics, and eventually your initially monochromatic source is very broadband. This is called, "higher harmonic generation."
It's also possible to generate lower frequencies through "difference frequency generation", so if you transmit at f and 0.9*f, you get a signal at f-0.9*f = 0.1*f. So if what this guy says is true, his panel is likely producing very strong signals at high frequencies (he indicated up to 100 KHz if I recall correctly) and generating difference frequencies in the audio range.
Hope that helps.
Well if we remove reflections from the situations, you'll start noticing other effects. Air isn't uniform, you've got nitrogen, oxygen, co2 etc. The molecules are moving around in a big sea of chaos, different temperatures, different pressure. When a sound wave is moving through the air, the "signal" will slowly deteriorate with distance. High freqs are usually the first to go. If you are familiar with a sound, you can judge the distance by the lack of timbre. But since anechoic chambers have been non existent in our evolution, we've relied heavily on reflections in outdoor environments.
My opinion is this has a lot to do with the familiarity of your house. Your brain instantly recognizes the sound as a slammed cabinet door. It then filters through the possibilities and locates the probable source of the sound based on a general direction.
One of the first days at a new work place, I heard a weird crunching sound. My brain was telling me the source was outside the door. I had a quick look and nothing was out there. I went back to my desk and heard it again. Turns out it was a contractor walking on the roof. Whenever I hear that crunching sound now, my brain tells me the sound is coming from above me. Occasionally we have visitors come by and they have no idea what the weird crunching sound is and where its coming from. But due to my familiarity with the sound and environment, I can pinpoint the contractors location on the roof.