Before and after photos
Thank you so much for this help, I've been having this problem for months and couldn't find any solutions on-line until i came across this. The tooth brush didn't appear to be doing much for me, so I flicked out the dirt of the speaker grill using a sharp needle.
I've taken before and after pictures for comparison, it made me realise just how blocked they were before. Even though it's not 100% clear, it's still a vast improvement in sound compared to before.
Link to photos: imgur.com/a/vM1M5#0