Gongs, according to Britannica online, are metal flat round musical instruments which usually have the rim turned downwards Striking the gong is done by means of a leather beater or felt beater on the middle area of the gong itself.
This can produce a definite or indefinite pitch.
The vibration resounds from the centre.
In some instances, one can have rimless gongs but the more widely used are those with rims.
Gongs were used in China from as early as the 6th century, in Java from the 9th and in England, they have excavated a deep rimmed Roman one from the 2nd Century BC in Wiltshire!
Their use is therefore from centuries ago.
The orchestras in the West usually use a flat-shaped gong that has an indefinite pitch.
