PURPOSE: To realize an interface of a speech synthesizing device whose circuit and control are simple, by forming a composite parameter memory interface and a composite control interface in the same structure, and unifying the interface.

CONSTITUTION: A control device 1 is connected to a speech synthesizing device 2 through an interface 3. The interface 3 is connected to a bus 5 through a parallel interface adaptor 4 at the side of the device 1, and on the other hand, connected to a microprocessor unit (MPU)7 through a parallel interface adaptor 6 at the side of the device 2. A synthesizer 8 and a memory controller 9 are connected to the MPU7, and a composite parameter memory 10 receives an address through a line 11, and sends and receives a data through a bus 12. A control command is defined newly in order to control the synthesizer 8 and the memory 10 in the same way. A composite parameter is read out of the memroy 10 through the controller 9, supplied to the synthesizer 8, and a synthesized voice is sounded from a loudspeaker 13.