I would like to start a discussion involving how sound works.

[ymalmsteen887]

You are confusing things here. If loud enough, people 500ft away certainly can affect the volume of people near you. This is where your intensity et al (that I've been trying to get you to read) comes in.

Have you ever been in a stadium? If I'm stood next to you (and it's only me and you in there) it's quite easy to hear me. Now put a few thousand people around us all talking at the same time and it's significantly more difficult to hear you - to the point you have to shout.

Of course, there will be a distance at which it makes no difference - but this is where acoustics come in and specifically constructive interference - concert halls and theatres are designed with this in mind.


You do realize instruments don't have set volumes don't you. You can play pianissimo (quietly) or fortissimo (loudly) - those are just two, but by utilising the various playing techniques you can achieve quite a lot. Including hearing a soloist over the backing.

Off topic for a second but is this orchestra playing unamplified?

http://www.youtube.com/watch?v=dYecLvwOiVA&playnext=1&list=PL88DE08D9FEF14799

 

[JaredJames]

Off topic for a second but is this orchestra playing unamplified?

http://www.youtube.com/watch?v=dYecLvwOiVA&playnext=1&list=PL88DE08D9FEF14799

I want to say yes (notice the design of the stage - that's not just for looks).

But there are noticeable microphones around, so I'm not perfectly sure. However, I'd say those mics are purely for recording it not for amplification.

 

[ymalmsteen887]

I want to say yes (notice the design of the stage - that's not just for looks).

But there are noticeable microphones around, so I'm not perfectly sure. However, I'd say those mics are purely for recording it not for amplification.

I think the microphones are for recording in 2ch audio for later viewing. Why would an orchestra use amplification wouldn't audiophiles complain about that?

 

[JaredJames]

I think the microphones are for recording in 2ch audio for later viewing.

Sounds about right.

Why would an orchestra use amplification wouldn't audiophiles complain about that?

Sometimes the instruments alone just aren't powerful enough to do the job. Although these situations aren't particularly common for your usual orchestra performances.

 

[ymalmsteen887]

something I don't understand about harmonics. If all musical notes are made up interger frequencies then how come different instruments sound different not to mention the different kinds of flutes gutiars drums etc, can sound different. Same with the human voice like people singing the same vowels yet sound different and even males are distinguisable from females and yet individual males and females can be told apart. How is this explained.

 

[Pythagorean]

something I don't understand about harmonics. If all musical notes are made up interger frequencies then how come different instruments sound different not to mention the different kinds of flutes gutiars drums etc, can sound different. Same with the human voice like people singing the same vowels yet sound different and even males are distinguisable from females and yet individual males and females can be told apart. How is this explained.

The harmonic profile is distorted by reality. That is, real strings aren't massless, don't have perfect tension, there's nonlinear effects (aeolian harp effect, possibly)

So each set of strings is going to have their own specifications based on these "flaws".

Also, there's the sounding technique. If you strum a guitar and wait a couple milliseconds, the higher harmonics die out quickly, leaving a more mellow, pure tone. But with a violin, you're always scratching the string with the bow, so you're not letting the harmonics dies out; you continuously agitate the string, so violins have richer harmonics.

look up "timbre"

 

[ymalmsteen887]

The harmonic profile is distorted by reality. That is, real strings aren't massless, don't have perfect tension, there's nonlinear effects (aeolian harp effect, possibly)

So each set of strings is going to have their own specifications based on these "flaws".

Also, there's the sounding technique. If you strum a guitar and wait a couple milliseconds, the higher harmonics die out quickly, leaving a more mellow, pure tone. But with a violin, you're always scratching the string with the bow, so you're not letting the harmonics dies out; you continuously agitate the string, so violins have richer harmonics.

look up "timbre"

I have looked up timbre. So are you saying that there is more then just the integers. Why doesn't the voilin bowed sound like a guitar being picked continuously. That only tells me why the sound changes on the guitar and not the violin.You said nonlinear effects if you take the fundamental note of a 82hz guitar note and a 82hz cello note that would just be a sine wave so how is it that instruments ,voices sound different?

 

[Pythagorean]

I have looked up timbre. So are you saying that there is more then just the integers. Why doesn't the voilin bowed sound like a guitar being picked continuously. That only tells me why the sound changes on the guitar and not the violin.You said nonlinear effects if you take the fundamental note of a 82hz guitar note and a 82hz cello note that would just be a sine wave so how is it that instruments ,voices sound different?

No, it's still the harmonic series. The point is that you have a different ratio of amplitudes across the spectrum for different timbre. So different harmonics will be more pronounced for different instruments (all harmonics are still there in all cases, just to varying degree) .

And no, it's not true that a real note from an instrument produces a sine wave. Sine waves are an ideal. Like I said earlier, their is really a distribution of frequencies, which doesn't look anything like a sine wave. Even before you consider harmonics, you can't really just strike one exact note, there will be a small distribution around that note. Then a bunch of harmonics, depending on the physical properties of the resonating body (String, drum membrane, flute cavity, whatever...)

Why doesn't the voilin bowed sound like a guitar being picked continuously

picking delivers an impulsive force (very fine point in time and space) followed by letting it ring... even when you're doing tremolo, the small space between picks is sufficient and still doesn't compete with the constant agitation of the bow. Bowing imparts a friction force (spread across time and space). The friction between the bow and the string causes little super-tiny impulses to be delivered smoothly. Even between impulses of some particular chunk of surface contact, there's always another area of contact causing another impulse, so you get a sustain.

So basically one big, slow pick vs. thousands of rapid, tiny picks. Much different emergent result.

 

[ymalmsteen887]

No, it's still the harmonic series. The point is that you have a different ratio of amplitudes across the spectrum for different timbre. So different harmonics will be more pronounced for different instruments (all harmonics are still there in all cases, just to varying degree) .

And no, it's not true that a real note from an instrument produces a sine wave. Sine waves are an ideal. Like I said earlier, their is really a distribution of frequencies, which doesn't look anything like a sine wave. Even before you consider harmonics, you can't really just strike one exact note, there will be a small distribution around that note. Then a bunch of harmonics, depending on the physical properties of the resonating body (String, drum membrane, flute cavity, whatever...)


picking delivers an impulsive force (very fine point in time and space) followed by letting it ring... even when you're doing tremolo, the small space between picks is sufficient and still doesn't compete with the constant agitation of the bow. Bowing imparts a friction force (spread across time and space). The friction between the bow and the string causes little super-tiny impulses to be delivered smoothly. Even between impulses of some particular chunk of surface contact, there's always another area of contact causing another impulse, so you get a sustain.

So basically one big, slow pick vs. thousands of rapid, tiny picks. Much different emergent result.

About the violin thing that's not what I meant I am saying they sound different regardless how you play them say you played a violin with a pick and did some rapid picking and then a guitar and then a bango they all sound different. You said because of the different levels in the harmonics then how come when I change the equilizer for my on my guitar amp I can never make it sound like another instrument see this is what i am asking?

 

[Pythagorean]

About the violin thing that's not what I meant I am saying they sound different regardless how you play them say you played a violin with a pick and did some rapid picking and then a guitar and then a bango they all sound different.

Ah, ok. But I already told you the different physical characteristics of the instrument alter the harmonic landscape of any given note.

violins have f-holes and hourglass shape bodies

guitars have round holes and a pear shape

The geometry of the resonance chamber thus has an effect on the sound too. Violins also have shorter length strings at different tensions. There's a variety of different strings you can use for both: nylon and steel are the popular contemporary materials. They all have different resistances to motion as the waves try to bend the strings under tension.

You said because of the different levels in the harmonics then how come when I change the equilizer for my on my guitar amp I can never make it sound like another instrument see this is what i am asking?

Because we're talking about a spectrum a lot more complex than a couple of knobs at discrete locations in the spectrum; there's a time-scale associated with the events, so you'd have to have thousands of equilizers that change with time (to account for attack, decay, and vibrato). You would need a high quality synthesizer to even come close. But even synthesizers can't do the real thing.

Remember that a note is not really just one event. It's a complex architecture of millions of events over different spatiotemporal scales. Your equalizer naively filters the waveform every x milliseconds to eliminate each frequency. There are several micro sound events happening within each note, so you have to consider the function of time.

If you're interested in the math/engineering aspects, here's an example of an attempt to model attack and decay:

http://www.rs-met.com/documents/notes/AttackDecayEnvelope.pdf

 

[ymalmsteen887]

Ah, ok. But I already told you the different physical characteristics of the instrument alter the harmonic landscape of any given note.

violins have f-holes and hourglass shape bodies

guitars have round holes and a pear shape

The geometry of the resonance chamber thus has an effect on the sound too. Violins also have shorter length strings at different tensions. There's a variety of different strings you can use for both: nylon and steel are the popular contemporary materials. They all have different resistances to motion as the waves try to bend the strings under tension.



Because we're talking about a spectrum a lot more complex than a couple of knobs at discrete locations in the spectrum; there's a time-scale associated with the events, so you'd have to have thousands of equilizers that change with time (to account for attack, decay, and vibrato). You would need a high quality synthesizer to even come close. But even synthesizers can't do the real thing.

Remember that a note is not really just one event. It's a complex architecture of millions of events over different spatiotemporal scales. Your equalizer naively filters the waveform every x milliseconds to eliminate each frequency. There are several micro sound events happening within each note, so you have to consider the function of time.

Ok so a bass guitar would have its own unique qualities separate form a double bass but what about drums how come you don't have to tune a drum when a song changes key. I heard it doesn't have a tonal quality so is it not made up of integers if not then what. Also what about earthquakes are they the same as white or pink noise?

 

[Pythagorean]

Ok so a bass guitar would have its own unique qualities separate form a double bass but what about drums how come you don't have to tune a drum when a song changes key. I heard it doesn't have a tonal quality so is it not made up of integers if not then what. Also what about earthquakes are they the same as white or pink noise?

I'm not completely sure about less ideal resonators. I play stringed instruments, so I think about the physics a lot more with strings. Having tonal quality means you can associate a particular frequency with it. Noise is an example of a sound that doesn't have tonal quality (so maybe the harmonics from the drum are approximately as loud as the fundamental).

I don't know about earthquakes.

 

[ymalmsteen887]

Does anybody else know about the harmonics of a drum and why they are not tonal?

 

[nasu]

Does anybody else know about the harmonics of a drum and why they are not tonal?

Technically, the drums don't have harmonics and some authors would say that they don't have a pitch. What they mean is that the frequencies of the "harmonic" components are not multiple of the fundamental. So when you hit the drum you produce a sound that is a combination of various components but those components are not in harmonic ratio.

 

[ymalmsteen887]

This is what I was asking at the begging if you have a sound source approaching you at 80 miles per hour and you hear 40hz, what would the frequency be if moitionlesss and when leaving you?

Also say you decide what the pressure is motionless what changes the attenuattion when leaving and coming towards you?

 

[JaredJames]

This is what I was asking at the begging if you have a sound source approaching you at 80 miles per hour and you hear 40hz, what would the frequency be if moitionlesss and when leaving you?

Also say you decide what the pressure is motionless what changes the attenuattion when leaving and coming towards you?

What you are talking about now is the doppler effect and you certainly haven't asked this before.

 

[ymalmsteen887]

What you are talking about now is the doppler effect and you certainly haven't asked this before.

I know its called the doppler effect and its relevant to my question about why certain frequencies travel farther than others like if the source is moving away its still producing the samw amount of energy though, right so the lower frequency should travel just as far but not farther, am I wrong?

 

[JaredJames]

Once again, higher frequencies experience more attenuation than lower ones and so don't travel as far.

I have already been through this with you, multiple times. Now you're asking the same thing all over again.

 

[ymalmsteen887]

Not true. It's all about acoustics. One person clapping in a gym sounds different to one person clapping in a stadium.

Read here: http://en.wikipedia.org/wiki/Acoustics


I gave you the links to intensity and energy. You need to read them and ensure you understand them. They explain why waves only travel so far before they "don't matter".


More people clapping gives the perception of more loudness. Again, acoustics.

This is like saying 5 speakers give the same volume as 1 speaker. Although the sound system may show them giving the same output, the actual perceived volume will be louder. (Think of the difference between 2.1 and 5.1 surround sound systems.)


As above, more violins will give you more volume - but it's not a case of doubling the volume as you double the number of violins.

About the violins I meant to say that even if they are tuned perfectly no one person is starting at the exact same time and so the waves are not perfectly in phase and gives an orchestra its characteristic sound.

I read somewhere that all the violins don't contribute much to volume because even if you put two subwoofers in an enclosure the boost is like 3db and that's with bass this becomes less significant the higher in frequency you go.

 

[JaredJames]

I read somewhere that all the violins don't contribute much to volume because even if you put two subwoofers in an enclosure the boost is like 3db and that's with bass this becomes less significant the higher in frequency you go.

Correct, as I said, it isn't a case of double the speakers = double the volume.

 

[ymalmsteen887]

Once again, higher frequencies experience more attenuation than lower ones and so don't travel as far.

I have already been through this with you, multiple times. Now you're asking the same thing all over again.

Well I don't understand yet so I am trying to make this easier for me to understand.

i guess what I am saying it isn't really a lower of higher frequency.

If each frequency has the same amplitude means it has the same pressure that would mean that the lower the frequency the more pressure to have the same perceived volume as a higher frequency cause a tweeter can be ear piercing loud and you won't see it move but a woofer can be playing a 30hz frequency and be moving a lot and not be loud.

 

[JaredJames]

Do you understand the concept of attenuation and how (as I've linked to and explained previously) high frequency experiences more of it over a set distance than a low frequency does?

You keep jumping around different issues. One minute we're on the doppler effect, next your talking about frequencies and how far they travel and now you're on pressure levels.

Pick one, learn it and then move on. Learn the difference in terms (as I've kept telling you to and linking you to).

I'm sorry, but we're on page 3 soon to be 4 and it seems as if you haven't bothered to read anything anyone has written or linked to. We can't carry on like this. I have constantly asked you to check your understanding of the various terms and how they relate (I even pointed you to some specifics) but you haven't bothered. We need to focus on one aspect, get it clear and then move on to the next item. In your last three posts we've jumped around to three different areas (as above) and if this is how it is going to continue I feel I'm wasting my time, so I will respectfully remove myself from here.

 

[Born2bwire]

About the violins I meant to say that even if they are tuned perfectly no one person is starting at the exact same time and so the waves are not perfectly in phase and gives an orchestra its characteristic sound.

I read somewhere that all the violins don't contribute much to volume because even if you put two subwoofers in an enclosure the boost is like 3db and that's with bass this becomes less significant the higher in frequency you go.

That doesn't have anything to do with the relative phases. Doubling the amplitude only gives you an increase of 3dB.

 

[ymalmsteen887]

Do you understand the concept of attenuation and how (as I've linked to and explained previously) high frequency experiences more of it over a set distance than a low frequency does?

You keep jumping around different issues. One minute we're on the doppler effect, next your talking about frequencies and how far they travel and now you're on pressure levels.

Pick one, learn it and then move on. Learn the difference in terms (as I've kept telling you to and linking you to).

I'm sorry, but we're on page 3 soon to be 4 and it seems as if you haven't bothered to read anything anyone has written or linked to. We can't carry on like this. I have constantly asked you to check your understanding of the various terms and how they relate (I even pointed you to some specifics) but you haven't bothered. We need to focus on one aspect, get it clear and then move on to the next item. In your last three posts we've jumped around to three different areas (as above) and if this is how it is going to continue I feel I'm wasting my time, so I will respectfully remove myself from here.

Ok no I don't understand this stuff and how is pressure not related to how far something travels. Whats wrong with answering my other question.

I don't learn well from reading stuff I need back and forth dialoge and it sounds like your expecting me to have a certain understanding already. I am not well versed in this stuff I need very laymans terms of understanding this stuff. I just want to understand it for my own personal purposes, if this is a problem Ill leave. If I understood this stuff I would be jumping at the chance to teach someone else who wanted to learn. Also you may have to recommend what maths I need to know to understand what youre saying, attenuation was foreign to me before you brought it up and I still don't get it seems like it means loses energy over time.

 

[ymalmsteen887]

That doesn't have anything to do with the relative phases. Doubling the amplitude only gives you an increase of 3dB.

The Thing about phases has nothig to do with waht I said about the increrase in volume.

 

[ymalmsteen887]

That doesn't have anything to do with the relative phases. Doubling the amplitude only gives you an increase of 3dB.

If your talking about the violins sound not having anything to do with relative phase I would bel willing say otherwise that's what a chorus effect is like when a group of people sing the waves are not perfectly together if they were they would proabably combine to sound like one voice.

 

[JaredJames]

Whats wrong with answering my other question.

I don't learn well from reading stuff I need back and forth dialoge and it sounds like your expecting me to have a certain understanding already.

They are erratic, you don't concentrate on one topic, you are jumping around wildly.

If you stuck to one aspect, we'd have back and fourth easily but you go from one are to another and that makes any reasonable conversation impossible.

I don't expect you to know anything, but I do expect you to put some effort in. I need you to read the links provided and if you have questions, bring them up. The problem is you don't do that, you change subject and go off on a tangent.

Also you may have to recommend what maths I need to know to understand what youre saying

Well I have, it's in those links. I told you to look over the attenuation equation and you didn't come back with anything so I assumed you understood it.

attenuation was foreign to me before you brought it up and I still don't get it seems like it means loses energy over time.

Have you looked up attenuation? Have you asked about attenuation? No, hence there has been no back and fourth for you to learn from.

I can't guess what you do and don't know, you need to bring the questions to me. From the start, I pointed you to attenuation relating to high frequencies. You didn't question anything from the link so for me (and anyone else here) it's taken that you understood it.

 

[ymalmsteen887]

They are erratic, you don't concentrate on one topic, you are jumping around wildly.

If you stuck to one aspect, we'd have back and fourth easily but you go from one are to another and that makes any reasonable conversation impossible.

I don't expect you to know anything, but I do expect you to put some effort in. I need you to read the links provided and if you have questions, bring them up. The problem is you don't do that, you change subject and go off on a tangent.


Well I have, it's in those links. I told you to look over the attenuation equation and you didn't come back with anything so I assumed you understood it.


Have you looked up attenuation? Have you asked about attenuation? No, hence there has been no back and fourth for you to learn from.

I can't guess what you do and don't know, you need to bring the questions to me. From the start, I pointed you to attenuation relating to high frequencies. You didn't question anything from the link so for me (and anyone else here) it's taken that you understood it.

Ok Ill go back and read the links, just one simple question why does a higher frequency experince more attenuation, isn't sound just a particle bouncing into other ones like a domino affect?

 

[violentj]

Isn't it just compression of air waves?

 

[ymalmsteen887]

well I guess the compression happens because something has to move faster than the air can get out of the way so wants so wants it compresses it will spread out to reach equlibrium

 

[JaredJames]

Isn't it just compression of air waves?

What's an "air wave"?

well I guess the compression happens because something has to move faster than the air can get out of the way so wants so wants it compresses it will spread out to reach equlibrium

Air can get out of the way?

OK, all stop. I think we need to go right back to the beginning here. Forget attenuation, and all the frequency stuff, let's start with what sound is. No wonder it's been a dead stick.

We need a medium for a pressure wave to travel through - no sound in space.

The medium we are concerned with is air.

A speaker for example, pushes molecules of air into the next ones, which are pushed into the next ones and so on - the wave travels. This is the same for any medium through which a pressure wave travels.

It is only a sound, strictly speaking, when it arrives at your ears and your brain interprets it as such.

 

[ymalmsteen887]

What's an "air wave"?


Air can get out of the way?

OK, all stop. I think we need to go right back to the beginning here. Forget attenuation, and all the frequency stuff, let's start with what sound is. No wonder it's been a dead stick.

We need a medium for a pressure wave to travel through - no sound in space.

The medium we are concerned with is air.

A speaker for example, pushes molecules of air into the next ones, which are pushed into the next ones and so on - the wave travels. This is the same for any medium through which a pressure wave travels.

It is only a sound, strictly speaking, when it arrives at your ears and your brain interprets it as such.

Yeah I got that so far a guitar string moves pusihing the air next to it and pushing the air next to it right.

 

[JaredJames]

Yeah I got that so far a guitar string moves pusihing the air next to it and pushing the air next to it right.

Correct. Just remember, nothing is "getting out of the way".

 

[ymalmsteen887]

Correct. Just remember, nothing is "getting out of the way".

So how do you show that there is a wave. I know how to determine the wavelength speed of sound divided by frequency.Basically what represents the peaks and valleys of the wave in air?

 

[JaredJames]

So how do you show that there is a wave. Basically what represents the peaks and valleys of the wave in air?

When sound travels through the air the molecules don't move up and down as you see on an oscilloscope (a sine wave).

It is a pressure wave - a longitudinal wave (http://en.wikipedia.org/wiki/Longitudinal_wave).

The molecule moves forward away from the source, hits the next molecule and moves back. The distance from the starting location to the peak (the point the particle begins to move back to its original position) is the amplitude. The particle then moves back past the original position and repeats the above, eventually slowing to a stop at it's original position. It is measuring this motion that gives you the sine wave appearance on an oscilloscope.

Now, read this too: http://en.wikipedia.org/wiki/Sound

Start at the top and make sure you understand what is there. Any questions, just ask.

I know how to determine the wavelength speed of sound divided by frequency.

Don't jump ahead, let's get you up to speed on what sound is first.