A struck vessel that sounds to be heard at a distance. A bell announces without saying what.

The noticing of what was there and unnoticed. Detection finds; it does not judge.

The asking sound at a door — consent's opening move: announcing presence and waiting to be welcomed.

A message sent to make someone aware of something now. It interrupts on purpose, which is why it must be worth it.

One who has asked to keep receiving. A subscriber consented once and may withdraw at any time.