Place it at the moment a message appears on screen, then add the bell ding after the reply is read to mark the exchange as complete, keeping the two alerts close together in the edit.
关于此声音
This is a short notification tone, a brief electronic alert designed to catch attention without lingering. It gives a quick sense of arrival, the small lift that tells someone a message has landed and is worth checking now, rather than a joke or a dramatic sting.