Acoustic insulation or more commonly known soundproofing is used to prevent any unwanted noise and sound from entering a certain room. There are a lot of different materials and ways how acoustic insulation is used. Mainly the result is either sound reduction or sound absorption. In both cases the disturbing noise will either be a lot quieter or even disappear at all.
The main idea behind all kinds of acoustic insulation is to block the way of the sound waves which as we all know is the way how sound is spread everywhere. Thus, depending on the frequency, size and shape different materials have various qualities of how much sound they can block or absorb.
As the street noise is becoming more and more annoying nowadays as the number of cars and people on the streets increases, in most of the construction for new buildings acoustic insulation is already in use. This means that the soundproof materials have already been built into the walls and floors of the house, so you do not need to install any additional acoustic insulation afterwards. As a result less street noise will be able to enter your home and you can enjoy more peace and quiet than in a lot of the old houses without any acoustic insulation.