A signal processing system includes microphone units connected in series and a host device connected to one of the microphone units. Each of the microphone units has a microphone, a temporary storage memory, and a processing section for processing the sound picked up by the microphone. The host device has a non-volatile memory in which a sound signal processing program for the microphone units is stored. The host device transmits the sound signal processing program read from the non-volatile memory to each of the microphone units. Each of the microphone units temporarily stores the sound signal processing program in the temporary storage memory. The processing section performs a process corresponding to the sound signal processing program temporarily stored in the temporary storage memory and transmits the processed sound to the host device.