Abstract: A method and apparatus for determining concordance between an analysis signal with at least one reference signal. The smoothed signals or envelopes are formed of a signal which is to be examined and at least one reference signal. A pulse train is generated for each of the smoothed signals or envelopes, and comprises pulses present during the time for a predetermined polarity of the smoothed signal or envelopes relative a threshold signal. The pulse trains are compared at regular intervals with each other, simultaneous coincidence of pulses in both trains at a predetermined number of consecutive comparisons constituting the criterion that the signals which are to be examined are in concordance with the reference signal. For carrying out this signal examination there are circuits means (2, 4) adapted for forming the smoothed signals or envelopes of the signals. The outputs from said means are connected to one input of a comparator (6) for each signal. A threshold signal (U.sub.Ref1, U.sub.