Many witnesses over the centuries have reported that fireballs are accompanied by a low thunder-like noise coincident in time with the meteor flash. These sounds cannot originate acoustically since sound waves cannot not travel fast enough to be heard at the same time as the meteor flashes.
The best explanation for many of these simultaneous meteor sounds is offered by Colin Keay. He suggests the sounds arise by electrophonic transduction. The wake of the fireball traps its magnetic field which creates very long radio waves which travel at the speed of light. The radio waves engender audio waves by interacting with ground-level objects such as trees or spectacles. This is still a controversial idea even though the sounds have now been recorded by several researchers. The same principle may explain reports of auroral sounds, animal unease prior to earthquakes, and sounds heard prior to a nearby lightning strike.
The usual electrophonic explanation fails for some short duration "pops" and staccato "clicks" which accompany certain meteors. Luigi Foschini and Martin Beech suggest such short duration pulses are generated by a strong electric field across the shock wave propagating in the plasma formed by the catastrophic disruption of the meteoroid in the atmosphere.
Did you see that thread on the comet that was viewable in N.E. USA yesterday?