Sometimes when I ride up behind people on the paths, they are wearing ear buds and they cannot hear you, even when you speak to them very loudly and directly.

Some ear buds block out outside noise.
I want some of those.

I bought some noise cancelling earbuds from Target but they don't work. Can anyone tell me what to look for? I saw one pair that worked but they didn't have any kind of markings on them. They had flat cables, fwiw.
TIA.