The indoor air of high-speed vehicle is automatically controlled by computer located inside the passenger car to make passengers feel optimal atmosphere. Through sensors, computer inside the passenger car can receive conditional information such as temperature and humidity of indoors and outdoors, and maintains the optimal indoor temperature and humidity automatically.
There are often inconvenience of feeling ear-ringing while taking a high-speed trains or airplanes. These phenomena occur by pressure-difference between indoors and outdoors of a passenger section, and in case of high-speed railroad, it happens during going through a tunnel. However, when the speed of the train is over 5km/h, high-speed train intercept the outer air with swollen rubber around the entrance due to computer orders in passenger car. Especially, it automatically shuts down the ventilation system while going through a tunnel in order to prevent ear-ringing phenomena by restraining air changes inside the passenger car.
The reason general trains are so loud is because of the noise and vibration created by joints on the rail. High-speed rail does not have any joints, and therefore much less noisy and shaky nevertheless the far faster speed.
High-speed rails are made by 300m long rails using special welding and moved to install location by special truck, then again welded within every 300m to become sequel welded rail. General railroads are still composed of joint-existing rails, but now in progress of replacing them with sequel welded rails.
Also, the wheels of high-speed vehicle are between passenger cars and not under the passenger car like general railroad vehicles, therefore reducing noises and turbulence due to wheels. Another reason of reduced noise is because of using electricity and not the diesel engine as activating power .
