Check these plugs out. I've heard from several reviewers that they work better than custom molded ones as they allow certain tones in while stopping the louder, lower tones. I haven't tried them, mind you, but they've been on my wishlist for a while and will likely pick them up.
https://smile.amazon.com/dp/B00RM6Q...olid=1WS9VO01QQ7YK&psc=1&ref_=lv_ov_lig_dp_it
Check out this video some more suggestions:
https://smile.amazon.com/dp/B00RM6Q...olid=1WS9VO01QQ7YK&psc=1&ref_=lv_ov_lig_dp_it
Check out this video some more suggestions: