Device for forming a simulated stereophonic sound field

DETAILED DESCRIPTION It is an object of the invention to provide a device for forming a sound field comprising cascade-connected twin-T circuits to produce complementary subsignals and having peak values in frequency characteristics of respective signals equalized with a resulting balanced frequency band.
It is another object of the invention to provide a device for forming a sound field adapted for use as a 4-channel stereophonic signal reproducing device having a simplified circuit construction for producing rear sounds with low distortion.
It is still another object of the invention to provide a device for forming a sound field adapted for use as a 4-channel stereophonic signal reproducing device capable of forming a sound field free from unnaturalness and filled with feeling of presence.
According to the invention, in cascade-connecting a plurality of twin-T circuits having different null point frequencies, peak values in frequency characteristics are caused to be equalized with one another by decreasing frequency characteristics outside of the section between the null points in correspondence to decrease in the frequency characteristics of the section between the null points.
For achieving this, the frequency characteristics on the lower frequency side are decreased by a low frequency signal attenuating element whereas the frequency characteristics of the higher frequency side is decreased by a high frequency signal attenuating element.
In another aspect of the invention, in preparing rear sounds in a simulated fashion when the device is used as a 4-channel stereophonic signal reproducing device, the above described construction is utilized to produce rear 2-channel stereophonic signals from a difference signal between input 2-channel stereophonic signals.