Why A noise blanker targets impulse noise, short spikes like ignition or power line arcing. It uses a wide-bandwidth auxiliary detector to sense the pulse before the narrow IF filter stretches it out, then briefly gates or mutes the signal path for the microseconds that the pulse lasts. Because the blanking interval is so short, speech is essentially unaffected while the pop is removed.
Watch out Clipping noise peaks describes an automatic noise limiter (ANL), an older audio-stage circuit that chops off anything above the audio peak level rather than gating the receiver; it is less effective on sharp ignition pulses.
Blanker blanks: it briefly turns the receiver off during each pulse. Limiter clips, blanker gates.