It is very difficult to inform anything where there is huge crowd accumulated. In such situations it is necessary to have a sound system to make any announcement. It is required by the places like public transportation vehicles and facility, sports stadium, school, live or recorded music venues or event, commercial buildings, and more. To make the announcement audible for everyone it is good to install a high quality sound system. The most suitable sound systems are pa systems.
Such public address systems will give you all the equipments that a perfect sound system needs such as amplifiers, micro phones, loud speaker and more. As every place has its own requirement, it comes in different range. For example at airport ship pa systems whereas at outdoor places horn loud speakers are used. Many online companies sold it at good price.
So, as per the requirement one can purchase and install it.
Source: http://portable-sound-system.blogspot.com/2018/07/shop-pa-systems-at-best-price.html