An audio processing apparatus that includes a first filter for converting n-channel (n1, positive integer) audio signals input from at least one signal source into two-channel signals, a pair of second filters to which two-channel output signals from the first filter means are input and which have transfer functions that are not correlated, and an output unit for supplying a pair of output signals from the pair of second filters to left and right loudspeaker units of a headphone device.