A similarity determining apparatus is disclosed which determines whether a query signal and a search signal are similar to each other or not. The similarity determining apparatus determines weighting values for elements of a signal characteristic of a first type, which are used in determining the distance between a signal characteristic of a first type of a search signal and a signal characteristic of a first type of a query signal, depending on a second type of signal characteristics. The similarity determining apparatus calculates the distance between the signal characteristic of the first type of the search signal and the signal characteristic of the first type of the query signal, based on the determined weighting values. The similarity determining apparatus calculates the distance between a signal characteristic of a second type of the search signal and a signal characteristic of a second type of the query signal.