The loudness of sound also depends on the area of the vibrating body. Greater the area of the vibrating body, louder is the sound produced.
If you take two drums, one small and the other big, and beat both of them to produce vibrations in them, We will notice that the sound produced from the big drum is louder than that produced from the small drum. In temples, you must have noticed that the bell with a big case produces a louder sound than that with a small case.