Exemplary noise reducing methods and systems are configured to acoustically reproduce two electrical noise reducing signals at two opposing positions in a helmet; to pick up sound at positions in the vicinity of the positions where the noise reducing signals are reproduced; and to generate the two noise reducing signals from error-signals and reference-signals. For each noise reducing signal, the corresponding error-signal is generated from the sound picked-up at the same position where the respective noise reducing signal is reproduced; and the reference-signal is generated from the sound picked-up at the position where the respective other noise reducing signal is reproduced.