# Tagged Questions

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### Do we hear sounds differently on the highest mountains?

Some searching gives that above 6,000 meter altitude the air density is less than half of that at sea level. Speed of sound is about 15-20% slower and "acoustic impedance" seems to change too. Do ...
2k views

### Why do bubbles make a sound?

I have an understanding of how bubbles work. They encapsulate air (or other fluids) in a membrane caused by surface tension. When they pop, there is often a sound. Sound is a type of energy, kinetic ...
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### Compression vs Rarefaction in Sound Waves

I am currently looking into solutions for Sound Classification, and I came across Ludvigsen's methodology (if anyone wishes to refer to it). The problem is that a sample graph of amplitudes in one of ...
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### How quickly should a fluid come to hydrostatic equilibrium?

Let's say I'm holding a one-liter water bottle, full of water, which I then drop. Before dropping the water bottle, the equilibrium is for there to be a pressure gradient in the water canceling the ...
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### (air pressure and displacement) Isn't this image wrong?

Isn't this figure wrong? P(x,t) = -B(dy/dx) . If the derivative of air displacement has a maximum, then this is where the pressure is minimum, not maximum as this figure suggests. Could someone ...
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### Why does sound need air in order to travel?

I know that in space, because of vacuum that we can't hear voices or sound to be specific, why is that? Why does sound need a medium to go through?
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### Why does a microphone membrane only measure pressure and not particle velocity?

Microphones (e.g. condenser microphone) are assumed to have a voltage output proportional to the sound pressure at the diaphragm. If the operating principle is that the voltage output is proportional ...
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### How far do air particles move when a sound wave passes through them?

How far do air particles move when a sound wave passes through them? I know that they don't actually travel, the question is how far do they oscillate or what is the physical amplitude of the ...
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### Logarithmic intensity formula factor?

In formulae for sound intensity and sound pressure, there is a logarithm part for the logarithmic increase of the quantity we're studying, and also a numerical factor 10 or 20 depending on the ...
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### Can random constructive interference with sound waves cause damage?

Any two sound waves have a random chance to constructively interfere with each other at a given spot and this will cause an increase or decrease in pressure. So is it possible that a large number of ...
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### Lethality of sounds and extreme “loudness”

In theory, could pure sound be lethal? How loud would it have to be? Also, which events are the loudest in the universe, and how loud are they? I'm confining attention to events which occur regularly, ...
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### Why does the balloon pop?

When we pierce a balloon with a sharp needle, it pops and produce a great sound. But, It doesn't pop when we open the mouth of the balloon (through which we have blown air)... So, Why doesn't the gas ...
2k views

### How can sound waves propagate through air?

We know that the sound waves propagate through air, and it can't travel through vacuum. so the thing that help it doing that is the air's molecules pressure. So my question how can that happens? I ...
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### What is the cause of noise generation at my bike helmet

I am looking for anexplanation of this phenomenon: I was riding my bike, (not driving it, was sitting on the back seat) with the helmet on. While the glass of the helmet was intact, I could hear ...
2k views

### Why is there a 90˚ phase angle between particle velocity and sound pressure in spherical waves?

My text says that in a plane sound wave (or in the far field), particle velocity and pressure is in phase. As we move closer to the sound source (to near field and more spherical waves), the phase ...
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### what is the relationship of sound volume to atmospheric pressure?

what is the relationship of sound volume to atmospheric pressure? if I was in a plane with a cabin pressure equal to 8000 feet would the volume drop be noticable?