Explain this to me - How a speaker works question

[flxnimprtmscl]

Ok, there might be a very simple answer to this but I don't know it A quick browsing of howstuffworks.com turned up nothing either. Anyway, here's the question. How can a speaker play multiple notes/sounds at the same time?

A speaker works by translating the electrical signal from the tape/cd/mp3 player, etc into vibrations of the cone which moves air and creates the sound. Right so far? So, for example, lets say I'm sitting here with my electric guitar and I play the low e string once and let it sustain. Now at this point the speaker has taken the signal, determined how it needs to vibrate to produce that sound, and is moving in such a way to produce it. But, while I'm letting that note sustain I also play the high e string. Now it has two notes at completely opposite ends of the spectrum to deal with and it has to vibrate in two completely different ways right? So, how does it do it?

 

[95SS]

BS alert

I asked the same question to a speaker guru, and his explantation was that different areas of a speaker cone can play different frequencies at the same time. I make no claim as to the truth of this statement, just stating what I was told.

/BS Alert

 

[SludgeFactory]

It's still a single waveform.

 

[InverseOfNeo]

Its why you have the woofers and the tweeters:beer::beer:

 

[Kelvrick]

Isn't this the purpose of 2-way, 3-way and such speakers? To more accurately create the different sounds?

 

[fredtam]

Originally posted by: SludgeFactory
It's still a single waveform.

Exactly. How do you here different notes at the same time? How does a mic pick them up. It is the same just reversed.

 

[Viperoni]

I believe that the individual frequencies get summed into one.... which at higher levels can lead to InterModulation Distortion, which happens when a driver attempts to play two or more frequencies and can't do it. This is similar to trying to get a tweeter or subwoofer to play full range... the tweeter won't be able to handle the bass and the subwoofer would likely not be able to produce high's cleanly.

Picture a graph of a pair of frequencies; on the X-axis you have time starting from 0, and on the Y-axis you have amplitude. Suppose one frequency is f(x) = sin(x) and the other is g(x) = sin(2x)... your resulting sound would be = f(x) + g(x) = sin(x) + sin(2x), which is the graph of sin(x) added to the graph of sin(2x); one frequency added to another.

This partially leads into why 3 or higher way speakers are around; by forcing each driver to play a smaller range of frequencies, less IM Distortion results, and overall sound quality typically improves.

 

[Fiveohhh]

Originally posted by: Kelvrick
Isn't this the purpose of 2-way, 3-way and such speakers? To more accurately create the different sounds?

A sub can produce lower sounds more accurately and a tweeter higher sounds, but hes asking how a single speaker can play two pitches at once say a 100hz wave and a 110 hz wave. I believe Sludge factory answered it in the most simplistic way)

 

[95SS]

Originally posted by: Kelvrick
Isn't this the purpose of 2-way, 3-way and such speakers? To more accurately create the different sounds?

True, multiple driver speakers seperate the frequencies out, what about when the source has two different frequencies that would be played by the same driver. If 500hz and 750hz were sent to a three way speaker, they would both be produced by the midrange driver.

 

[fredtam]

Originally posted by: 95SS

Originally posted by: Kelvrick
Isn't this the purpose of 2-way, 3-way and such speakers? To more accurately create the different sounds?

True, multiple driver speakers seperate the frequencies out, what about when the source has two different frequencies that would be played by the same driver. If 500hz and 750hz were sent to a three way speaker, they would both be produced by the midrange driver.

Yep. built in crossovers.

 

[Lithium381]

Originally posted by: 95SS

Originally posted by: Kelvrick
Isn't this the purpose of 2-way, 3-way and such speakers? To more accurately create the different sounds?

True, multiple driver speakers seperate the frequencies out, what about when the source has two different frequencies that would be played by the same driver. If 500hz and 750hz were sent to a three way speaker, they would both be produced by the midrange driver.

well, depending on the crossover...!

think of it this way, what do you hear? the mic just pics that up, what it "hears" and puts it into an electrical signal, it's actually only one wave-form........think about it, seems logical to me, but i can't explain things ver well

 

[Bleep]

For cripes sake he was not asking how multi speaker setups seperate out the sounds. Lets say he is using a pair of cheap headphones, no crossover no multispeaker setup. Viperoni has a explanation that is acceptable but not entirely correct.

Bleep

 

[Cerb]

Your ears, a speaker and a mic have a lot in common. You a have a single thing in your ear that takes in all those frequencies, right?

OK. Take a rope. whip it. A ripple flows down the length. That's that sine wave. Now whip it lightly and then hard quickly.
You get an odd ripple. Well that's basically what's going on, but much, much faster.
When multiple sounds come to your ear, it vibrates. Effectively it makes it into a wave, and it's one wave--just like what a mic gets or a speaker outputs. It's the change in wavelength and amplitude that goes on that allows you to actually pick out different sounds (assuming just tones, not going into positioning things or any of that).
In fact, here's an even better way to visualize it. Open Winamp. Play a song that's relatively simple, with plenty of guitar or organ (I just checked it out with Queensryche - Bridge). Get the little visualization thingie to the wave. You can see, in many places where there's just a guitar twang or two, something very close to a normal sine wave, and then the changes as other things go into it.

 

[boomdart]

Originally posted by: Viperoni
I believe that the individual frequencies get summed into one.... which at higher levels can lead to InterModulation Distortion, which happens when a driver attempts to play two or more frequencies and can't do it. This is similar to trying to get a tweeter or subwoofer to play full range... the tweeter won't be able to handle the bass and the subwoofer would likely not be able to produce high's cleanly.

Picture a graph of a pair of frequencies; on the X-axis you have time starting from 0, and on the Y-axis you have amplitude. Suppose one frequency is f(x) = sin(x) and the other is g(x) = sin(2x)... your resulting sound would be = f(x) + g(x) = sin(x) + sin(2x), which is the graph of sin(x) added to the graph of sin(2x); one frequency added to another.

This partially leads into why 3 or higher way speakers are around; by forcing each driver to play a smaller range of frequencies, less IM Distortion results, and overall sound quality typically improves.

Your reasoning would explain why you can play a 30hz tone on a subwoofer, and it play fine at insane levels. However, if you play a 30hz tone, a 50hz tone, and a 60hz tone all at the same time, you will hear distortion.

By the way, distortion will not hurt a speaker. It will only hurt when you hear the speaker clip, cut off and back on, or snap.

 

[Ornery]

As Cerb mentioned, your eardrum has only one surface to pickup sound, yet is able to differentiate between different sounds heard at the same time. Maybe this is why chords sound pleasant, because they are easier for your ear to reproduce.

 

[Krakerjak]

The explanation that it is still a single waveform is the best.

Look here at the waveforms.
Using fourier to discover the frequencies hidden in those funky looking waveforms shows how more than one pitch can be heard at the same time (at least it appears to be at the same time).

Think of a speaker vibrating in the fashion of one of those wierd audio waveforms, it would vibrate in an irregular or non-periodic fashion.
When you play a single note your speaker will vibrate the same way over time, moving the same distance in and out. Adding another note to that sound will cause the speaker to vibrate in an unsteady pattern, different sections of the speaker will not vibrate at different frequencies.

I hope that made sense