When riding in minecart, sometimes sound of the minecart starts fast turning on and off, stay like that for a while and then start normaly playing again. Also when sound is turning on and off and i hit Esc, normal sound of minecart starts playing until i close the menu (In single player).

What I expected to happen was...:
When i ride in minecart, i expect sound to play constantly.

What actually happened was...:
Instead, sound sometimes plays with short and very common pauses. Also when i hit Esc, while is this happening, normal minecart sound starts playing, until i close the menu.

Steps to Reproduce:
1. Build long track of powered rails with redstone torches next to it.
2. Place minecart on it and ride from one end to another couple of times.
3. If bug don't appear, try starting your ride from random spots on track.

Video demonstration: http://www.youtube.com/watch?v=KGBikJ-HMhQ&feature=youtu.be