The Bell, known in Sanskrit as the Ghanta/Ghanti is used in all
poojas for invoking the Gods. The ringing of the bell produces what is
regarded as an auspicious sound. It produces the sound Om, the universal
name of the Lord. There should be auspiciousness within and without, to
gain the vision of the Lord who is all-auspiciousness. Another significance of ringing the bell is that they help drown any inauspicious or irrelevant noises and comments that might disturb or distract the worshippers in their devotional ardor (dedication), concentration and inner peace.
In mandirs (Hindu temples) aarti is performed daily by pujaris (priests). There is usually a 'mangala-arati' first thing in the morning, another later in the morning, one at lunchtime, and the final aarti of the day at sundown.
Devotees sing various types of kirtana and bhajans during the aarti ceremony. The pujari performing aarti first purifies his hands with sacred water from the acamana cup. He then sprinkles three spoonfuls of water over a conch, and blows it three times. He then lights an odd number of incense sticks (usually three) from a ghee lamp standing beside the altar. While ringing a small bell, he waves it seven times around the deities, and then he waves it once to the assembled devotees.
The fine combination of pure brass and bronze produces a harmonious and rich tonal sound when rung by hand while singing the Aarti or even chanting traditional Mantras for worship. Prayers or Pooja of any kind on any occasion are incomplete without the joyous sounds and chanting of Bell.
We chant this mantra when we ring the bells :
Agamaarthamtu devaanaam Gamanaarthamtu rakshasaam
Kurve ghantaaravam tatra Devataahvaahna lakshanam
I ring this bell indicating the invocation of divinity, So that virtuous and noble forces enter (my home and heart); And the demonic and evil forces from within and without, depart.