A new experimental technique is proposed to estimate the bandwidth of the auditory‐filter mechanism when detecting short‐duration sinusoidal signals masked by wide‐band noise. The experiment requires the use of only wide‐band noise and two signals of the same frequency, power, and duration, but having different energy density spectra. The special feature of this technique is that the subjective impression made by the masking noise remains the same throughout the experiment unlike experiments that employ progressively changing bandwidths of the masking noise. This avoids the possibility of any change in the parameters of the detection mechanism due to changes in the subjective impression made by the noise. The analysis makes use of the energy detection model consisting of a bandpass filter, square‐law rectifier, and an integrator to describe the auditory detection system. A rectangular filter and an LCR single tuned filter have been considered in the analysis. From the experimental results it is found that the rectangular filter provides a better description of the auditory‐filter mechanism than the single tuned filter. The bandwidth estimates show an increase with signal frequency. The results also support the idea of a minimum auditory‐filter bandwidth for a continuous or long‐duration signal and increased values for short‐duration signals depending on the signal duration.