Does (or can) Cycles release VRAM after rendering a frame?

I’ve been searching for an answer to this question, but I have had no luck so decided to ask here. This is regarding rendering an animation in with Cycles using the GPU and CUDA.

After rendering a frame, before moving on to the next, is the memory holding the rendered frame released? If not, why not and could it be in future?

What similarities and differences are there between the handling of frames and of tiles?

Bonus question: Does rendering with sound impact VRAM/GPU use?

Thanks to anyone who can answer any of these questions!