Why do we feel pain in our ears while our train travels through a tunnel?
If you happen to be traveling in a train (running faster than 40-50 km/hr) which passes through a long tunnel, then you must have experienced pain inside your ear drums. It is harmless but it could be irritating at times. So why do we feel such a thing?
This happens because of pressure difference between the air behind your ear drums to air around you. When fast moving objects passes through a narrow long duct, they create low pressure around them, so when you are traveling in a train, pressure decreases in a much faster rate than the pressure inside your body could adjust, hence causing ear drum membrane to swell out- the reason for the pain.
This pain/sensation is similar to what some people might experience while plane takes off and lands. but the reason for creation of that pressure difference is different, you can read about it here.
Coming back to the topic, shown below is the graphic of roughly what happens when train travels through a tunnel. Not all the air is pushed out side like a plug as soon as train enters, instead air flows around the train in the space between tunnel wall and train, with high velocity (as area decreases velocity increases for given flow rate), this high velocity creates low pressure zone ( Bernoulli equation), and hence the low pressure created causes our ear drum to 'swell' out.
Generally our body adjusts through this pressure changes easily without us even noticing, but when pressure changes are sudden our body fails to keep up with the changes. This causes the pressure inside our body to be high or low depending upon changes that occur in the surrounding. In present case, pressure is higher than the surrounding, hence air inside out our body wants to come out. the reason we fell that pain or sensation in our ears is simply because our ear drum are really sensitive and there exists a pocket or cavity ( middle ear) where air is trapped. So the pain that we feel is basically our ear drum trying to pop up.
Generally our body adjusts through this pressure changes easily without us even noticing, but when pressure changes are sudden our body fails to keep up with the changes. This causes the pressure inside our body to be high or low depending upon changes that occur in the surrounding. In present case, pressure is higher than the surrounding, hence air inside out our body wants to come out. the reason we fell that pain or sensation in our ears is simply because our ear drum are really sensitive and there exists a pocket or cavity ( middle ear) where air is trapped. So the pain that we feel is basically our ear drum trying to pop up.
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| http://hearinghealthmatters.org |
Having said that what could be done to avoid that? Well, one could try anyone of these possible solutions to 'Equalize' the pressure:
- Yawning
- With a mouthful of air, close your mouth and pinch nose your nose shut; gently force air out until ears your ears pop. (Do this VERY gently)
- Chewing gums
Perhaps the next time you pass through a tunnel at-least you would know what is happening and how could you make it a little more comfortable. (It is comforting to know a little more about the reason for an uncomfortable situation :P)
