| 摘要 |
<p>- 34 - RCA 73,587 A system is provided which synthesizes stereophonic sound by developing two separate sound channels from a single monophonic sound source. A synthetic stereophonic sound system constructed in accordance with the principles of this invention may be advantageously utilized in combination with a visual display such as a television receiver. A monaural signal (M) is applied as the input signal for a transfer function circuit of the form H(s), which modulates the intensity of the monaural signal as a function of frequency. The intensity modulated H(s) signal is coupled to a reproducing loudspeaker, and comprises one channel (B) of the synthetic stereo system. The H(s) signal is also coupled to one input of a differential amplifier (40). The monaural signal (M) is coupled to the other input of the differential amplifier (40) to produce a difference signal (M-H(s)) which is the complement of the H(s) signal. The difference signal is coupled to a second reproducing loudspeaker, which comprises the second channel (C) of the synthetic stereo system. In accordance with a preferred embodiment of the present invention, a stereo synthesizer is utilized as the sound reproducing system of a television receiver, with the reproducing loudspeakers located on either side of the kinescope. The amplitude -vs- frequency response curves of the two output channels (B,C) have crossover points at which the amplitudes of the two response curves are equal, which effectively centers sounds at these frequencies between the loudspeakers. Two crossover frequencies are chosen to occur at approximately the frequency of peak intensity of the human voice, and at the center frequency of the second (articulation) formant frequencies of the human voice so as to effectively center voices on the kinescope while preserving the ambience effect of other, more randomly distributed sound signals. Centering the second formant frequencies also provides increased quality in the reproduction of speech sounds.</p> |
