How to get rid of turtle beach headphone smells (foam padding from over ear headphones)?

My bro was using my turtle beach x11 and when I got round to using them they stank what I can only describe as sick. I have used deoderant like lynx but the smell just mixes, and I have tried oust on them which hasn't worked. I have also tried hanging the ear covers outside for a while but nothing seems to get the smell away. Does anyone know of any way to properly get rid if the smell other than just buying replacement covers?