Rings a Bell is an expression used to indicate that something is familiar or that it has been heard before. This phrase can be used to describe the sound of two different objects, Gongs and Clangs. Gongs are large, metal discs that are struck with a mallet to produce a deep, reverberating sound. Clangs are similar to gongs, but they are usually made of metal and produce a sharper, more metallic sound. Both of these sounds can be used to evoke a sense of familiarity or recognition, hence the phrase 'Rings a Bell'.