# Amplitude of sound?

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Hello everyone,

I understand wavelength,frequency but not the amplitude. Can anyone here explain what do they mean by the amplitude. In some places they say it is the maximum displacement of a particle but isn't this the wavelength. My other confusion with sound is this

Ok here the amplitude is the top bit from the graph. So it is maximum change in pressure. So why is it measured in m. Can anyone tell me what does this mean in particle level.

If this is how sound spreads in all directions. I don't get it. Shouldn't sound follow a straight path like the longitudinal wave in the top picture. I thought sound was a longitudinal wave then why is travelling circular like this. Can anyone relate the longitudinal wave with this pic and tell how are they related. Is the wavelength in this case the distance between two waves or

Inside each ripple is their a longitudinal wave?

Any help in any of these questions would be much appreciated :-) :-)

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the wavelength is the distance between 2 peaks or 2 troughs that are next to each other (one complete cycle) on the X axis.

the Amplitude it the Height of this wave, the Y axis.

think of it this way, if you listen to tone it will have a frequency (say middle C for instance), now you turn up the Volume and the tone is still middle C but Louder, you`ve increased the Amplitude

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The amplitude of the wave is the height of a crest or the depth of a trough. From the peak to the axis.

See the attached image for visual interpretation.

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Sound does travel in a straight line, but in straight lines in all directions out from the source. The real picture of the propagation of the wave would actually be a sphere around the source of the sound. The sound isn't traveling in a sphere or circle, it is traveling in straight lines from the source outward, creating the emergent spherical shape.

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Hello everyone,

I understand wavelength,frequency but not the amplitude. Can anyone here explain what do they mean by the amplitude. In some places they say it is the maximum displacement of a particle but isn't this the wavelength. My other confusion with sound is this

Ok here the amplitude is the top bit from the graph. So it is maximum change in pressure. So why is it measured in m. Can anyone tell me what does this mean in particle level.

If this is how sound spreads in all directions. I don't get it. Shouldn't sound follow a straight path like the longitudinal wave in the top picture. I thought sound was a longitudinal wave then why is travelling circular like this. Can anyone relate the longitudinal wave with this pic and tell how are they related. Is the wavelength in this case the distance between two waves or

Inside each ripple is their a longitudinal wave?

Any help in any of these questions would be much appreciated :-) :-)

Your picture is showing the top view of a 2-D representation of the waves, where the lines are the peaks.

Amplitude of sound is related to the pressure or density of the air (or other medium)

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I think the source of your confusion is that there are different kinds of waves. In a sound wave, amplitude is usually measured in pressure. But with waves in water or something, it's going to be the maximum displacement of a particle. This is NOT wavelength. The wave moves across the surface, but any individual particle only moves up and down. Or another example: flick the end of a rope. You can see the wave traveling down its length, but clearly any point on the rope is only moving up and down.

To help you visualize the "expanding in all directions part," just imagine dropping a stone in a pool of water. Waves move outward in all directions in straight lines, forming patterns of expanding circles. A sound wave is similar, but in three dimensions, so it's going to make patterns of expanding spheres, where the spheres are "made of" regions of higher and lower pressure.

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Thank you everyone for your help.

I think the source of your confusion is that there are different kinds of waves. In a sound wave, amplitude is usually measured in pressure. But with waves in water or something, it's going to be the maximum displacement of a particle. This is NOT wavelength. The wave moves across the surface, but any individual particle only moves up and down. Or another example: flick the end of a rope. You can see the wave traveling down its length, but clearly any point on the rope is only moving up and down.

So in sound amplitude is not measured in m is it measured in terms of pressure. Particles in a sound wave are travelling back and forth parallel to the direction of the wave. How are they moving up and down. Isn't that transverse wave?

Ok I edited the image of the sound wave and divided it in to sound waves. So I'm assuming the amplitude here is the thickness of the lines and wavelength is the distance between the lines. Am I right? Looking forward to your replies

Thanks again for each and everyone who has replied

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thats not a wavelength you pointed out.

the wave length should be from where the lines are densest to the next part where they are densest.

the amplitude is how dense the lines are at the peak versus how not dense they are in the trough.

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• 9 months later...
Hello everyone,

I understand wavelength,frequency but not the amplitude. Can anyone here explain what do they mean by the amplitude. In some places they say it is the maximum displacement of a particle but isn't this the wavelength. My other confusion with sound is this

Ok here the amplitude is the top bit from the graph. So it is maximum change in pressure. So why is it measured in m. Can anyone tell me what does this mean in particle level.

If this is how sound spreads in all directions. I don't get it. Shouldn't sound follow a straight path like the longitudinal wave in the top picture. I thought sound was a longitudinal wave then why is travelling circular like this. Can anyone relate the longitudinal wave with this pic and tell how are they related. Is the wavelength in this case the distance between two waves or

Inside each ripple is their a longitudinal wave?

Any help in any of these questions would be much appreciated :-) :-)

In a sound wave You have nine amplitudes.You have displacements of molecules, velocities of molecules,velocities and air pressure, each with components in 3 dimensions. for sound in air, in water,in wood,etc. Each component has its own frequency,Amplitude etc.. For amplitude we ha ve peak a., mean a., effective a., mean square a. hreskold

amplitide legal loudness limits .etc

Is this clear enough ?

Morp

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