Speech processing device, speech processing method, speech processing program, attachment method for speech processing device, ceiling member, and vehicle

In order to achieve a speech processing device in which a voice of an occupant of a vehicle is inputted and high quality emphasized speech is outputted regardless of the direction of speech and undesired sound, a speech processing device is provided with: a first microphone which is provided to either a ceiling member inside the vehicle, or an attachment to the ceiling member, and which receives an input of a mixed sound having, mixed therein, the voice of the occupant of the vehicle and undesired sound within the vehicle, and outputs a first signal; a second microphone which is provided to a position either in the ceiling member inside the vehicle or in the attachment to the ceiling member, said position being further away than the first microphone from the point of view of the occupant of the vehicle, and which receives an input of the undesired sound within the vehicle while either the ceiling member inside the vehicle or the attachment to the ceiling member is used to block the voice of the occupant of the vehicle, and outputs a second signal; and a undesired-sound suppression means which outputs an emphasized speech signal on the basis of the first signal and the second signal.