The spectrum of Barkhausen noise has been measured in iron and analysed using signal analysis techniques. The results suggest that the mean duration of the voltage pulses caused by the domain reversals is less than 5 x 10-5 s and that a domain reversal triggers other domain reversals with a time delay normally of 1 to 2 ms. Delays of up to 10ms do occur. The results agree with those obtained by Sawada. The technique allows detailed information of the dynamic nature of domain reversals to be obtained quickly and with little sample preparation.