The development device includes a development member and a circulation member. The hydrogen generation system has: a storage means for storing a chemical hydride solution; a reactor containing a catalyst; and a pump for supplying the chemical hydride solution from the storage means to the reactor so that the chemical hydride solution reacts to generate hydrogen in the presence of the catalyst. The first active portion is polarized in a direction parallel to the electric field generated in the first active portion, and the second active portion is polarized in a direction opposite to the electric field generated in the second active portion, thereby making it possible to suppress the crosstalk even when a high density arrangement of the pressure chambers is realized. The structure is useful for learning to play the instrument, while not appearing as a learning device.