With instruments such as the piano, xylophone or harp a glissando is a quick slide in which we hear one note after another because the pitches between the notes cannot be played. On the piano there are two ways to play a glissando: either on the white notes or on the black notes. At the end of the piano piece called "Ondine" from "Gaspard de la Nuit" by Maurice Ravel both these types of glissando can be heard. The pianist has to play a glissando with tips of the fingers or the finger nails. It can be quite painful to practise them a lot. Harpists are very fond of playing glissandi. By changing the position of the harp pedals a harpist can change the scale which will sound when the glissando is played.