Hero999
Banned
No, it's not that simple.Doubt me? Submerge yourself in water and have someone standing right next to you scream as loud as they possibly can (with their upper body out of the water) You'll barelly hear a thing because there's an air column still in your ear that meets with the water, and an air cavity at the surface of the water to the person yelling.
If I'm submerged and you're shouting, of course most of the sound will be reflected but this isn't the case.
If the speaker is placed above the water with no tube, when the cone moves most of the pressure wave will be coupled straight to the air and escape. When the tube is added, when the cone moves, the air is now trapped inside the tube, when the cone moves forward, the air will push the water inside the tube out of it and when the cone moves back, it will suck more water into the tube. This is because the tube has greatly improved the impedance matching between the speaker's cone and the water.
Take a piece of string, hold one end in your hand, get a friend to hold the other end and pull tight. If you shout at the string and your friend puts his ear next to the other end of the string. He'll be able to hear the shouting but only because the sound is travelling through the air.
Now attach a plastic cup to either end of the piece of string and repeat the experiment. If you shout into one cup and he puts his ear to the other cup, it'll be very loud. This is because the cups have improved the impedance matching between your mouth and his ears to the string.
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