Sound pollution is similar to noise. It is the unwanted sound that falls on our ears. For example any excessive volume of music or voice near or inside hospitals is noise pollution. Main harms it does to us are that we lose concentration, we cannot think freely and hence we cannot prepare for exams well.
Often in India we have a lot of celebrations going on in every locality during major festivals. During that period, the prayers and other music played on loud speakers is an example of sound pollution. It is not wanted by every one. There are many who are disturbed by that sound.
In many developed countries, sound pollution is not allowed by the law. People are punishable under law. People do not sound the horn on cars or motorbikes unless required. However, in India, people use a lot of horns on vehicles. This is also sound pollution.
Sound of some high frequency and volume more than some decibels is very irritating to the ears and to the heart. 30 decibels during the night and 50 decibels during the day are tolerable. Beyond that it is noise pollution.
There is an increasing awareness of sound pollution among Indians. During Diwali, people are trying to avoid the crackers as they make a lot of sound. Often many machines which constantly move and rotate like a saw cutting wood or metal, makes irritating sounds. Also, these days, people do not want to reside close to the main road as there is a lot of sound pollution.