The bell, known in Sanskrit as the Ghanta is used in all Hindu worship.
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.
Even while doing the ritualistic aarati, we ring the bell. It is sometimes accompanied by the auspicious sounds of the conch and other musical instruments. An added significance of ringing the bell, conch and other instruments is that they help drowned any inauspicious or irrelevant noises and comments that might disturb or distract the worshippers in their devotional ardour, concentration and inner peace.
As we start the daily ritualistic worship (pooja) we ring the bell, chanting:
Kurve ghantaaravam tatra
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.