“I think when I first learned that the sounds of the animals in nature documentaries were not real, or, rather, were at least done in post it was less of a surprised amazement, but was more of a “oh of course!”. Even with the knowledge that most sound effects aren’t actually recorded on set in fiction films, for some reason (I suppose due to the non-fiction nature) you don’t expect to be tricked by something like a documentary It is supposed to be so truthful you end up treating it like CCTV footage, or something out of a case file. But ultimately it’s still telling a narrative, especially with things like Blue Planet II, you tend to follow a singular ‘character’ whose story is told and so in many ways these kinds of documentaries are quite similar to fiction in that the footage that is recorded is edited together, and the sound and foley are done in such a way as to seem exciting and entertaining, yes these are meant to inform but they are also meant to entertain. It’s all about providing a satisfying experience for the audience, just having the sound from on set would be underwhelming as compared to the majesty of nature and so certain tricks have to be played as not to disappoint the audience. “