| 摘要 |
A system is provided for creating sound represented by the varying width of a motion picture film soundtrack, which provides a "flat" frequency response up to 12.5 kHz with maximum phase coherence, even though the film speed is only 62 % to 78 % of the present speed of 90 feet per minute (27 meters per minute). The projector photocell which detects a slit-shaped area of light passing throug the soundtrack, produces an output that is amplifed so the amplification is progressively greater at higher frequencies, with the gain at 12.5 kHz being at least 6 dB greater than at 1 kHz. A photocell is selected whose output at 12.5 kHz is within 1 dB of its output at 1 kHz for light of a wavelength of substantially 1000 nanometers. |
