We have analyzed the response of a noisy Fitzhugh-Nagumo neuronlike model (FN) to subthreshold external stimuli. In contrast to previous studies we have focused our attention on high-frequency signals which could be of interest for real systems such as nervous fibers in the auditory system. We show that the noisy FN behaves as a stochastic oscillator with a characteristic time scale whose effects remain in a wide range of situations. In the nonadiabatic regime of frequencies considered in this work we report several resonant behaviors which resemble those of classical deterministic oscillators but never the typical stochastic resonance phenomenon so often observed for low-frequency signals.