The bell is used mainly at two places - One which we use in our temple room and the other we see in the temples. First of all let us understand about the bell we use in our temple room. Nowadays we come across articles of puja made up of various metals. They even have different artistic designs on them. As per the science of spirituality the bell should be made from either copper or brass. The carving of images of Garud or Nandi is allowed according to scriptures.
The Sound generated by the bell should be gentle and sweet. In a puja ritual the bell is used during such sub-rituals as waving Frankincense (dhoop) and Lamp as well as while performing arti for creating gentle sound. In a puja ritual what is the importance of sound and what happens on spiritual level can be understood by looking at a subtle drawing. The subtle drawing means a drawing which tells us about the subtle process which is going on at spiritual level about whatever we see with the gross eyes about an object or action.
Let us now see how the energy is emitted from the bell and what exactly happens with the help of a subtle drawing. The dome shaped body of the bell and the clapper when strike with each other create circles of chaitanya which are projected in the atmosphere. The sound generated simultaneously also emits frequencies of chaitanya predominant in Akash tattva (absolute ether element). We can see them in yellow colour. The stroke of clapper emits red coloured divine energy rays. The particles of divine energy which spread in the atmosphere and are of red colour are also seen here. The divine energy and chaitanya generated by the sound of bell drives away the negative energies. During a puja ritual as mentioned in scriptures when we do puja of bell as an initial part of puja, the bell is gently rang and following holy verse is recited, The purport being, 'I am ringing this bell to invoke Deities and to drive away demons.'
Now you must have understood the importance of bell and ringing of bell. It must also have been clear that the purport of the holy verse and the knowledge obtained through the medium of subtle drawing match with each other. One point is clear from the information we have got up till now that sound vibrations are created in every puja ritual with the help of two articles namely shankh and bell. Sound vibrations produced by shankh is called Shankhanad while that of bell is known as Ghantanad. The common property of both of them is they purify the atmosphere. The only difference is that while the sound vibrations from bell purify the atmosphere in the downward direction while that emanating from shankh purify the frequencies active in the upward direction. Hence both of them are very important in a puja ritual.