What are the spooky noises on Minecraft?

Usually I can tell when a sound is from a nearby mob, such as a squishy-like sound from endermen, slimy sounds from slimes, fizzing from creepers, groaning from zombies, etc. But sometimes there are those Really loud sound that don't seem to come from anywhere. Like lately there's been this intense drumming sounds. Once It kept repeating for over 30 sec, another time is just did it twice. I don't know what it is and I couldn't find a page about it on the Minecraft wiki. Does the sound have a source or is it just random?

I think they're just random sounds intended to creep you out. I normally find that you only hear them in dark areas.

These sounds, with few knowing their actual names are a medium to rare occurance in MC. They do not spawn completely randomly:
When a world is generated, the Minecraft programming sets a pattern, so if a player walks within range of a certain set of co-ordinates, the noise triggers. There are different volumes and types, some of them sound like screeching train rails, others like an echo or a swish'. There's no reason for the sound currently known, and no way to disable them (as far as I know). If they occur too frequently, e, g: 30 seconds, you should probably re-install as it might be a bug. Players once speculated that it was Herobrine's 'mark', but as he is proved not to exist, this is false information. The only possible explanation so far, is that they have a high chance of spawning near a deep cave containing Diamond!

Minecraft has alot of noises… Especially in caves and caverns… It's to add a sense of mystery and uneasiness.(Which would really happen if you found a massive cave underground.lol)

It's most likely a minecraft soundtrack, some of them will play from time to time, like when you're in caves you will hear an eerie sound.