Sound from the speakers of my MBPro with Touch Bar degrading
UPDATE: almost 3 months later, multiple updates down the road and upgrade to high sierra, I am sad to report that the issue still persist. I will probably have to return to the apple store to RMA my macbook...



I'm sorry I would comment on your post instead posting an answer but new account requires me to have enough rep....

I have the exact same  issue with my macbook pro 2017 15" with touchbar. 

I found that it happens only after going over around 85% volume. No matter which software provokes it.

Plugging and unplugging headphones work for me too. Also killing coreaudiod solves the issue but requires apps that were using the sound drivers to be restarted.

This is a real pain to manage.

I hope this is a software issue as it seems to have started right after Sierra was updated on July 27 2017.