Does an obsidian block affect sound transmission?

So I was slime-hunting because I heard the sound of a slime through the wall. I kept digging, following the sound of the slime, until I dug down to a lava pit, surrounded by some stone. I safely went down to the area, and the slime sound was getting louder and louder. The area was pretty small, and I did not want to fall into the lava. I had a water bucket with me, so I poured it on the lava and it turned to obsidian. Then the slime sound stopped. No more. Nada. I turned around and went back home, quite sad. Later, I thought:

• Could the obsidian mute the sound of the slime?
• Maybe if I dig through the obsidian, I will be able to find the slime?

Solution 1:

Ahh, I know what happened. The lava has a new sound effect (it has been in there for a bit but it is overall somewhat new if you have not been playing for a bit).

Most people mistake it -exactly- for what you did, the sound of a slime hopping around as opposed to the sound of the lava bubbling.

As far as sound transmission goes, obsidian is the same as any other block and does not hinder sound (Sound only falls off based on distance to its source). But to answer the question of how did you end up at lava while tracking a slime, you were actually tracking the lava bubbling SFX.

Solution 2:

Loudness of any sound is only determined by how close it is to the player.

Obsidian doesn't mute sounds. To prove this I just put a note block in the middle of a 5x5x5 obsidian box, and I could clearly hear the sound.
(Repeaters can pull redstone current through blocks, so I didn't have to make any holes in the box.)