Bells, chimes, or anything metal that can ring, tinkle, chime, and so on. Although, it doesn't have to be metal, but a metal sound from an electronic device can also work.
At the house in Leavenworth, Jessiana, Wesley, Lorien, and I have heard the doorbell ring. That house does not have a doorbell. The house is old, by American mid-west standards, being built in the late 1800's. All the doors, clearly, at some point in the past, did have doorbells. But between 2011 and 2013, none of the doors have doorbells of any sort. What is on the doors are the remains of the plastic frames of the electronic buttons that no longer exist. Hearing the doorbell has become a regular occurrence and is normal for us. Anyone who hears the the door bell answers with, “You are not allowed in unless we know who you are.” That has minimized spiritual exposure in the house.
If you hear a bell, where there is none be aware. The ringing of a bell is the announcement of something important. The underworld may be asking for entry, announcing a presence, or maybe giving an angel their wings (Which is something I doubt).
A bell that is used to “stir-up” or “call out” spirits, ghost, demons, shadows, or any variation of that “should” be made of metal. There is a reason why. Metal, minerals, gemstones are all considered to be in the “domain of the underworld” (please do not confuse this with Christian Hell). Whatever name you use to invoke the “god of the underworld” or “king of the underworld” doesn't matter. What does matter is that this personification is in charge of the spiritual concerns of “what lies beneath the soil” and that includes metal. To “make ring the bell” means that you are invoking that personification.
To “ring the bell” at a funeral, is to announce to the underworld that proper burial rites are finished, and that person is officially dead.
In a marriage or union (which should include adoption ceremonies), to make “ring the bell” announces to the underworld the proper completion of those rites, making the union official in heaven, on earth, and below.