When people say pollution, what usually come to mind are chemicals in the water, air, and land. Your friend may be saying something important, but all you can hear is traffic noise. The rock concert was great, but you have this strange ringing in your ears the day after, maybe even a headache. All the noise in the office - you just cannot concentrate and now it s making you quite irritated. Noise can be a type of pollution.
Bad noise can mask important sounds and communication.
Extremely loud sounds can cause injury and perhaps even death. But, the most likely effect of noise on people and animals is behavioral changes. The concept of noise pollution is now fairly common, along with many standards for safe noise levels in work places. Look around some day at the number of ear protection devices at construction sites and airports. There is sound underwater and many marine animals rely more on hearing than seeing.