To provide a processing apparatus that provides spatial extent by headphones.

The processing apparatus includes input terminals 15 to 19 that receive a plurality of audio input signals, an echo device 14 that includes a delay echo component simulating an echo sound of which a listener possibly listens to in listening environment, and receives a plurality of input signals to generate one group of output signals, and one group of head transfer functions 20 to 24 as a multi-input filter having 2 outputs that receives the output of the echo device. Consequently, the listener who is listening to outputs 47, 48 through headphones feels as if listening to the plurality of audio input signals from a plurality of loudspeakers disposed in the listening environment spatially apart in a plurality of corresponding directions.