Distorted ambient sounds

My ambient sounds (like cave sounds or Nether ambiente) aren't like the original ones. For example, cave sounds are more grave than normal ones, even if I can hear them correctly in the audio options. But they aren't the same in-game. Here two videos (I think it is the same sound type, you'll hear the difference between them. If they are not the same sound, here's a video so you can compare them: https://youtu.be/IiJZkpEuecc). Sorry if there's a bit Echo in the videos.