are sound waves effected by gravity?

Question

My employer is of the opinion that sound has a tendency to travel downwards. I don’t agree as I don’t believe sound waves are affected by gravity.

Answer 1

Sound is not directly affected by gravity but as sound can only exist in a medium then there are secondary effects.
Just sticking to sound in air I think all other effects being equal (unlikely) then sound will tend to be bent up. The speed of sound is greater in denser air which will tend to bend sound towards lower density = up. This is not gravity affecting sound, it is gravity affecting the medium that sound is travelling through.

Answer 2

Gravity keeps our oceans and our atmosphere on our planet, so without gravity, they would be dispersed uniformly throughout the universe, and probably never be dense enough to propagate sound. But within a body of water or within the atmosphere, the molecules are generally in equilibrium. The force of gravity is balanced by pressure from other molecules. If there is motion, it is due to other factors.

One example is the sea breeze. During the day, land heats up faster than the ocean, so the air above the land is less dense and rises, with the cooler air above the ocean blowing in to take its place. The opposite happens at night, resulting in an offshore breeze.

If you make a sound where the entire air mass is rising, the molecules carrying the sound are rising, so the sound would tend to move upward. That's a relatively small effect, since the speed of the sound is much higher than the speed of the air.

If there is a greater or different factor affecting sound travel, the right way to answer the question is (1) to research it, and see if someone else has already done (2), and (2) to investigate it. Ask your employer why he/she thinks it travels downward. Devise experiments that would show whether or not it happens. Propose theories to explain it. Discuss them with your peers. Test them. That's the scientific method at work.

Answer 3

sound travel in all direction, the sound wave are spherical.
Since the wave itself is only energy, and it has no weight gravity can't have effect on it.

the gravity as effect on the air particule that oscillate to create the sound, but it only cause the sound's intensity to decrease

The doppler effect has nothing to do with gravity, go read a physic book and you'll discover that the doppler effect is matter of movement.
When you stand still by the road, hitchhiking, and that a car pass in front of you without stopping, you hear the pitch's noise lower than it become higher as it passes you. that's the doppler effect. it's exatly the same you are in the car and that someone yell at you from the side of the road

Answer 4

Sound isn't affected by gravity and travels in all directions.

Sound is however affected by the direction of the wind. Sound travelling into the wind has a tendancy to be directed upwards, whilst if going with the wind it tends to get directed downwards.

Answer 5

The answer should be no. Gravity is measured by Mm / R^2. As sound waves are not known to have mass, they should not be affected by gravity. Should it be influenced by gravity, sending sould downwards should have been easy, while shouting upwards pretty tedious

Answer 6

Good question! And one I've never thought about before.

I'm going to buck the trend here and say that I think sound *is* affected by gravity.

Put simply, sound is carried by the molecules in whatever the sound is passing through, 'bumping' into each other until they eventually 'bump' into your eardrum and you hear the sound.

These molecules are physical and therefore abide by the laws of gravity. Common sense suggests, therefore, that they would find it harder to move upwards - because they are being retarded by gravity - than they would to move downwards - when they would be accelerated by gravity.

So, my money is on; yes, sound is affected by gravity and travels faster & further downwards than it does upwards. Furthermore, I'm guessing that sound travelling sideways (relative to the pull of gravity) also has a tendency to curve towards the ground. (Certainly, sound underwater curves due to changes in water pressure)

Let me try it another way…..

Sound is transmitted by the movement of molecules.

Molecules have mass and therefore they, and their movement, are affected by gravity.

If sound is transmitted by the movement of molecules and the movement of molecules is affected by gravity, it seems logical to conclude that the transmission of sound is affected by gravity.

Answer 7

You are right, your employer is wrong.

The only way sound is affected by gravity, is that gravity holds the air on the surface of the planet, which is of course, necessary to transmit the sound.

Answer 8

No, and I agree with you that sound waves doesn't affect by gravity, because sound waves is an echo of a force when the sound create, depends how loud can one make.

Answer 9

sound waves are definitely affected by gravity, since sound intensity decreases with increase in distance travelled.

Answer 10

the doppler effect is proof of that. >> particles are affected by gravity, sound is occilating air particles. However, if you yell up to a third floor window, they can barely hear you, but from the window, they can talk down to you in normal tone, go figure....