Ominous whispers and such

[Kedjane]

I can't agree at all with your opinion.

The purpose of the whispers is to add a sense of mysteriousness and supernaturalness, not mainly to scare the players. Not many people are afraid of whispers, obviously, and like several other things (the hatch, for example) was inspired by the TV series Lost where mysterious whispers in the jungle was one of the biggest mysteries at the time of the games release.
Also, since when is something a nuisance just because it doesn't mean anything? It is also Swedish messages backwards, though it's more of an easter egg than a meaning.

The reason you hear whispers near the artifacts is, correct, that they are related to the Tuurngait in an uncertain way. However, by merely touching the artifacts they only "drag you in" and make a sort of clone of you - which is the games saving function. The reason you can hear Clarence clearly is because he is just a single Tuurngaq who has possessed you - and apparently is the only single Tuurngaq to have possessed a person (or at least is the only known one) which is what causes the differences in the way Philip and the "greys" are affected by their Tuurngait. The reason you can hear the Hivemind clearly is, obviously, because it is the Hivemind. It is the "high council" being of the Tuurngait, the strongest and the one that speaks for the many. Also, I can't remember right now how you get sucked into the Hivemind's world, but if I remember it right Philip attempts to escape when things start disappearing and he falls unconscious: so this time it seems likely Philip was possessed by the "entire" Tuurngait gathering which causes the dreamworld aswell as the whole vividness, or the Tuurngait might just have made him fall unconscious (or he might have passed out because of all the crazy things going on) and him being unconscious contributed to the Hivemind's strength of speech.
I remember now that the Hivemind also speaks some before he passes out and that's probably because the Tuurngait no longer are communicating amongst themselves like they usually do, in the ending the Tuurngait are speaking to Clarence and 1) either speak openly so that both Clarence and Philip can hear them clearly or 2) their mental "transmission" to Clarence is so strong (as the Tuurngait is a mighty being) that it can be heard clearly in Philips mind aswell despite standing several meters away, suggesting the Tuurngait has very strong psychic powers (which also is proven in the latter dreamworld scene and the fact that next to everyone in the Shelter has been killed or "turned" by them).

Also in Unknown I don't think a whisper, if there is one, has to have a greater purpose. Whispers saying ominous and evil things like "you're all going to die" is very 90's. Mysterious whispers is fairly modern, kept so by the popularity of Lost.

Can't agree with the Alma part either. Alma is definitely not meaningless, she's a scare (in fact I believe we discussed some of FEARs scariest moments in some thread around here). In a horror game you can hardly say a scare is meaningless, can you?