I would compare it to books, where you have two kinds of narrators: A character-based narrator, who is bound to the physical limitations of the character. And an omniscient narrator, who is free to even read thoughts and be at different places at the same time or make connections across centuries.

So in movies you can have to kinds of camera. A character based camera, which sees things from the perspective of a character. Far away sounds are muffled, he can only guess who is hiding in the dark and far away explosions are usually depicted in the realistic fashion of hearing the blast wave much later.

But in many cases the movie will switch to the omniscient/omnipresent camera perspective. So you can watch a huge battle from high above, or see an explosion from a perspective which no character could have, like watching a space battle from the outside. In this case we are not a physical observer with a predetermined location and physical limitations. The camera represents an omniscient observer, which can hear characters speak in their space ships in real time, and can hear an explosion in exactly the same moment it happens. Like we can hear the battle-cries of soldiers on the ground in a huge army as they open their mouths.

Because our focus of attention / our virtual presence is right there at the center of the action. Our virtual persona is standing right beside the bomb and can hear the explosion instantly, while also being able to observe the whole scene around like a godly being would, not bound by having and eye and an ear at the same place.

So in many modern movies it goes like this:

1. Charaters sitting together in shelter (character camera)
2. The bomb ticks it final tick (omniscient camera right at the timer)
3. The bomb explodes cineastically - instant, clear explosion sound (omniscient)
4. The characters hear the muffled blast wave with a delay (back to character camera)

So we even hear the explosion twice, first from the omniscient instant perspective and than a second time with the limited sensors available to the characters from the character camera perspective.

I would compare it to books, where you have two kinds of narrators: A character-based narrator, who is bound to the physical limitations of the character. And an omniscient narrator, who is free to even read thoughts and be at different places at the same time or make connections across centuries.

So in movies you can have two kinds of camera. A character based camera, which sees things from the perspective of a character. Far away sounds are muffled, he can only guess who is hiding in the dark and far away explosions are usually depicted in the realistic fashion of hearing the blast wave much later.

But in many cases the movie will switch to the omniscient/omnipresent camera perspective. So you can watch a huge battle from high above, or see an explosion from a perspective which no character could have, like watching a space battle from the outside. In this case we are not a physical observer with a predetermined location and physical limitations. The camera represents an omniscient observer, which can hear characters speak in their space ships in real time, and can hear an explosion in exactly the same moment it happens. Like we can hear the battle-cries of soldiers on the ground in a huge army as they open their mouths.

Because our focus of attention / our virtual presence is right there at the center of the action. Our virtual persona is standing right beside the bomb and can hear the explosion instantly, while also being able to observe the whole scene around like a godly being would, not bound by having an eye and an ear at the same place.

So in many modern movies it goes like this:

1. Characters sitting together in shelter (character camera)
2. The bomb ticks it final tick (omniscient camera right at the timer)
3. The bomb explodes cineastically - instant, clear explosion sound (omniscient)
4. The characters hear the muffled blast wave with a delay (back to character camera)

So we even hear the explosion twice, first from the omniscient instant perspective and than a second time with the limited sensors available to the characters from the character camera perspective.