Most of the old temples in India have a large bell at the entrance that one needs to ring before entering the temple. Making temple bells is a whole science. These bells are not made out of ordinary metal, but a whole variety of them, including cadmium, lead, copper, zinc, nickel, chromium and manganese.
The proportion at which each one of them mixed is the real science behind making a bell. Each of these bells is made to produce such a distinct sound that it can create a harmony between your left and right brains. The moment you ring that bell, it produces sharp but lasting sound vibration which lasts for minimum of seven seconds in echo mode -- long enough to touch your seven healing centers (or chakras) in your body.
The moment bell sound happens your brain is emptied of all thoughts. Invariably, you will enter a state of trans where you are very receptive. This trans state is the one with inner awareness. Normally, you are so occupied in mind that the only way to awaken you is with a shock!
The bell works as anti-dote to the chaos of your mind. Before you enter temple it prepares you for the calming taste of of spiritual awareness you are going to experience.[ temples ]