Toward the beginning of the year, it was revealed that Microsoft was going to "unlock" the seventh core on the Xbox One's processor, enabling developers to eke just a bit more performance out of the console and offer more flexibility at resource utilization. It appears that Microsoft's move would inevitably be followed by Sony, as reports are now coming in that this will be made available on the PlayStation 4 as well.
This subtle change was highlighted in the latest changelog for the FMOD sound engine. Labeled as a "LowLevel API" update, it reads, "PS4 - Added FMOD_THREAD_CORE6 to allow access to the newly unlocked 7th core."
Ultimately, this changelog draws attention to a change that Sony's already made, and while the unlocked core could take on FMOD duties if developers want it to, it's now not going to be tied to any single purpose. Developers could make use of this core, for example, to boost AI, or any other process that has a heavy computation requirement. It could also be used to simply help ease the overall load, as any system function will tap on available resources from the CPU.
The reason both the Xbox One and PlayStation 4 had this seventh core locked was for the sake of optimizing the performance of the underlying OS. With both companies having made this change now, it could mean that improvements have been made to their OS under-the-hood to allow it to better cope with limited resources. It could also mean that both companies were simply playing it safe and affording devs as much flexibility and freedom they can offer. Locking down resources at the hardware level, dedicating them to specific functions like motion sensing in the case of Kinect, for example, can help guarantee a certain level of experience on that targeted function but also limit performance if an app doesn't make use of that function.
Either way, free CPU horsepower is never a bad thing.