Odd sound in certain areas?

I do not know if this is the correct place to post this, but I have a feeling it may be lore related. When you enter certain Realm Reborn areas (Sylphlands, The Unholy Heir, Lowe La Noscea also I think) there is a sound that rises...a low humming or moaning. What causes this sound? Perhaps a shard of Dalamud? Perhaps an area where a Primal has been summoned? Perhaps my client software is broken ?? I have always wondered what this sound is and have never seen any discussion of it elsewhere...a definitive answer would be appreciated from anyone that knows. Thank you.

What you're referring to as 'sound' is actually music that is part of the soundtrack; specifically the track Slither by Masayoshi Soken. There's no lore aspect to it - it's just Soken's way of having the music add a more creepy atmosphere to certain areas (the fact the track is only very short and ends after a few seconds is the giveaway).

I have the soundtracks and never noticed that was there...thanks for that :) It is really cool the sense of foreboding it lends when you enter those areas...like, WATCH OUT something is coming. Was kinda hoping there was a lore tie-in, but oh well. Still sounds great, as does all of Soken-san and the sound team's work in Eorzea. Thanks again for the reply Enkidoh :)