OS X Yosemite: FFXIV intermitent sound on crowded areas and FATEs

Every time I joine a new FATE or I get to a crowded area the sound starts going weird. The music stops all of sudden and I only hear some sound effects. When I leave the area I back the music but it's intermitent and I have to restart the client.

My computer is a Macbook Pro 15" Retina Mid 2015

OS X Yosemite 10.10.3

2.5GHz quad-core Intel Core i7
16GB of 1600MHz DDR3L onboard memory
512GB PCIe-based flash storage
Intel Iris Pro Graphics
AMD Radeon R9 M370X with 2GB GDDR5 memory and automatic graphics switching