A printing apparatus and preliminary discharge control method capable of minimizing the influence of a preliminary discharge operation on printing and keeping a short printing time are disclosed. The receiving chamber has at least two view holes formed at top and bottom sides thereof respectively, wherein the latter communicates with the gas chamber. Two other smaller leaflets extend around the posterior aspect of the valve. 5% accuracy improvement with 2\xd7-4\xd7 computational cost in the context of cluster analysis. The controlling device controls the amplifier so that the user can hear, at a second state that the ear is near to the speaker, the voice from the speaker when the data from the base station does not include the discrimination datum which represents the image datum.