Blinncraft is an audio conversion pack for Minecraft that replaces the sound effects in Minecraft with custom-made sounds I designed and recorded myself. Currently, it is not finished and it is currently in alpha, but you will notice the changes almost immediately. To make it backwards compatible with say 1.6.4, change the name of the sounds folder to sound, and it should work. I had to do the opposite to make it work on 1.7.10 and above.
Current Version - 0.0.5.
Blinncraft featured in a Let's Play: