I swear by: http://www.amazon.com/Alpine-EARWORK-Worksafe-Earplugs/dp/B003ZHU9YW/ref=sr_1_1?ie=UTF8&qid=1398661809&sr=8-1&keywords=worksafe

They are specially made to allow voice / normal talking through the filter, unlike solid foam ones.

Once trimmed, they are also invisible.