The response of an isolated magnetic bubble domain to pulsed magnetic fields normal to the film plane is measured with high spatial and temporal resolution. Digital signal averaging techniques are used on a succession of identical pulses, permitting changes in bubble radius to be measured to a precision of 2 nanometres, in successive time intervals of 10 nanoseconds. The radial wall velocity, obtained by differentiation, is determined with a precision of 0.2 metres per second. Significant “inertial” effects and velocity nonlinearities are seen at quite modest drive fields (a few tenths of kA/m, or, a few Oe) and wall velocities (a few m/s), in response both to an applied bias-field step and to a pulse. © 1975, IEEE. All rights reserved.