Thwack

The sound of a perfect loaf just out of the oven. It is a hollow sounds and is discerned by thumping the bottom of a loaf with the thumb or by flicking it with the forefinger and is still the best method known for testing whether a bread is finished baking. If there is a thwack and the loaf feels firm, it is done. If it feels firm but there is no thwack, that is, if it is still soft on the bottom but firm on the sides, it needs to go back in the oven, but out of the pan, for a few minutes.