The answers to that question are given in the old Vedic texts and Shastras.
You must have witnessed the ringing of bells during rituals and also before doing the darshan of the deity.
Your Page!
There are spiritual and scientific reasons behind ringing of bells. Ringing of bells has many health benefits too.
That is why not only in Hinduism, but other religions such as Buddhism, Jainism, Christianity also follow the ritual of ringing bells in temples and churches.
When being rung, its vibrating sound will instantly ward off any negativity in the temple vicinity.
When bells ring, a vibration is created in the atmosphere.
All the bacteria, microbes, and other harmful microscopic germs falling on the path of these vibrations get destroyed.