If you're really close, and the actual lightning bolt short (fewer opportunities for echoes and doppler effects), you'll hear it as a "crack", with very little in the way of rumbling afterward, and if there's wind, then there's ample opportunity for that to be further reduced. Short lightning bolts are more common in the shallower, less intense storm clouds we get in the UK in open-cell convection. Compare and contrast with a large storm in a continental area in a closed-cell meso-scale cloud system; it can seem like the thunder is pretty much a continuous crackle/rumble. In small clouds, lightning bolts might be only a km or so long, whereas large-scale systems (look up "anvil crawlers", or see this:
http://tiny.cc/axje6y) can be multiple kms long.