The present invention provides a cancellation signal which may be combined
with a radio or television program signal to provide a mix minus signal
for use in IFB communication with the talent. A cancellation signal
circuit is responsive to a talent signal to delay and gain adjust the
talent signal to provide the cancellation signal. The amount of gain and
delay necessary may be adjusted by an operator, or automatically
determined or set in response to the program signal or the mix minus
signal. Automatic operation is provided even in the presence of changing
delay and amplitude of the program signal or the talent signal component
thereof.