PURPOSE: To make it possible to display right and left levels of a stereophonic audio signal on the screen of a TV receiver with good response, by making use of the TV receiver.

CONSTITUTION: Either of right and left channel signals detected by level detectors 1 and 2 is supplied to comparator 4, and the other is polarity-inverted 3 and supplied to comparator 5. Comparators 4 and 5 are supplied with saw-tooth waves synchronizing with a horizontal scan and, when both the inputs agree mutually, generate pulses. From FF7 supplied with both the pulses as a reset pulse and set pulse, rectangular pulse train Y"1 is obtained which has the leading edge determined by one pulse and the trailing edge by the other pulse. This pulse signal is inputted to receiver 10 via vertical positioning gate 8 to provide amplitude modulation of a luminance signal. Thus, bright lines that correspond to right and left levels can be displayed on the screen of receiver 10 with good response.