mic static noise on mac?

Hey, I used to use my iphone headset on my Mac Book Pro an it used to work fine as a mic, They could hear me alright, But now whenever I use it, Sometimes its good and sometimes it just turns to static noise and my voice does not change volume levels, It's like the mic can't here me but it's just making annoying noise, I tried with my iBeats and S4 Headset, They all have the same problem.

The issue is in the mic so how do I fix it exactly ?
Thanks.