Pseudo-stereo circuit

A pseudo-stereo circuit comprising:

• an input terminal that receives an input monophonic signal to be processed;
• a phase-shift circuit that shifts a phase of the input monophonic signal by a phase shift amount that depends upon a frequency of the monophonic signal, to produce an output signal having a gain with respect to the input monophonic signal which is equal to or larger than a predetermined level over an entire frequency band thereof, and reaches a peak at a frequency at which the phase shift amount of the output signal with respect to the input monophonic signal assumes a value equal or closer to −π, and
• a mixing circuit that produces a first mixed signal by mixing a signal obtained by inverting a phase of the output signal of said phase-shift circuit with the input monophonic signal by a first mixing ratio, and produces a second mixed signal obtained by mixing the output signal of the phase-shift circuit with the input monophonic signal by a second mixing ratio, said mixing circuit generating said first mixed signal as a first audio signal carried by one of left and right channels that provide stereophonic audio signals, and generating said second mixed signal as a second audio signal carried by the other of the left and right channels,
• wherein the phase shift amount of the first mixed signal with respect to the input monophonic signal progressively changes in a predetermined direction as a frequency of the monophonic signal changes, and the phase shift amount of the second mixed signal with respect to the input monophonic signal is maintained at an almost constant value irrespective of changes in the frequency of the monophonic signal, said first and second mixing ratios being determined so that frequency characteristics of the gains of the first and second mixed signals with respect to the input monophonic signal are substantially identical to each other over the entire frequency band.