Noise Pollution from Cars
We all are aware of the exhaust pollution from combustible gas engine cars. But cars also produce noise pollution. If you define pollution as the introduction of unwanted contaminants into an ecosystem, then noise from car can be thought of as noise pollution. It introduces unwanted noises that disturbs an otherwise peaceful environment that causes discomfort to the inhabitants.
A single car driving along may not cause that much noise, but a whole multitude of cars going at fast speeds as in a freeway can cause a lot of noise. That is why some towns put soundwalls along the freeway to contain the noise pollution so that it does not disturb the inhabitants of the nearby houses.
Although these noise barriers can not eliminate freeway noise completely, it can cut it down by up to half. Depending on how tall they are and what materials they are made of, the amount of reduction can be a reduction of between five to ten decibels. This can mean making the noise of a tractor-trailer sound like the noise of an automobile. [reference: Federal Highway Administration]
Loud Speakers and Alarms
Besides pass-by noise, some cars have their loud speakers blaring with windows open so that everyone nearby can hear the driver's taste of music. Some with enhanced bass are so loud that it makes the whole car vibrate.
And if one such car passes by a parked car with an overly sensitive alarm system, then it might trigger the car alarm which by design is loud. This adds additional noise pollution to the existing noise pollution of the car with blaring loud speakers.
Of course, there are other things that can trigger a car alarm -- a cat, a stray ball, etc. It is worst when it happens at night or when the owner is not around to turn it off.
Not only does the alarm makes noise. But the act of activating the car alarm by remotely locking the doors causes noise. When you lock the doors with a car remote, many cars will make a beep to indicate that you have just turned on the alarm. Some beeps are louder than others. Some beeps are actually the car horn going off (which is loud). Other beeps are not tied to the car horn but a softer acknowledgment beep. Sensible owners sometimes disable this confirmation beep of which many system allow you to do.
Too much honking
Many drivers are using their horns way too much adding to the noise pollution. They honk when another driver is moving too slow. They honk when a driver starts off a second too late from a red light. They honk when another car do not let them in.
These are not situations for which the car horn was designed. The car horn was designed to alert other drivers of a potentially dangerous situation that they may not be aware of. The car horn is to alert drivers that "I am here" in the event that the other driver do not see you.
The excessive use of honks when their use is unwarranted adds to the noise pollution caused by cars.