Function of Bhavanga - Bhavanga-cittas and the sense-door process
An object which is experienced through one of the five senses is rūpa. Rūpa arises and falls away, but it does not fall away as rapidly as nāma. One rūpa can be experienced by several cittas succeeding one another in a process. When, for example, the rūpa which is sound impinges on the ear-sense it can be experienced by cittas arising in the ear-door process. Before the process starts there are bhavanga-cittas. The last bhavanga which arise before the sound can be experienced by the cittas of the ear-door process are : atīta-bhavanga (past bhavanga), bhavanga-calana (vibrating bhavanga), bhavangupaccheda (arrest-bhavanga).
When the stream of bhavanga-cittas has been arrested, the ear-door- adverting-consciousness]] (sota-dvaravajjana-citta) adverts to the object through the ear-door. This citta can be followed by other cittas which each perform their own function in that process before it falls away. Rūpa lasts as long as seventeen moments of citta counting from the atīta-bhavanga, the past bhavanga, there can be seventeen moments of citta succeeding one another if the sense-door process runs its full course. If the rūpa which will be object has contacted more than one atita bhavanga, it will have fallen away before the process can be completed, since it cannot last longer than seventeen moment of citta. A process can, after it has started, be interrupted, for example, after the votthapana-citta, before kusala cittas or akusala cittas can arise. It may also happen that the atīta-bhavanga is succeeded by the bhavanga-calana, but that the bhavangupaccheda does not arise; then there will be no process of cittas. Sound may, for example, impinge on the ear-sense and then the atīta-bhavanga which arises is succeeded by the bhavanga-calana. However, the bhavangupaccheda does not arise and thus the stream of bhavanga-cittas is not interrupted and the ear-door process cannot start. In that case the sound cannot be heard.
