Here is a schematic diagram illustrating the difference between impulse noise and narrow-band noise. The left column contains: (a) the waveform of a mixed speech with impulse noise, (c) the waveform diagram of the frame inside the red box in (a), (e) the log power spectrum corresponding to the waveform in (a), (f) the frequency diagram of the frame which is pointed out in (e) by an arrow. The right column contains corresponding schematic representations of mixed speech with narrow-band noise.