MacBook Air Speakers issue

I have been listening to various different types of music and sound on my Mac Air and i have noticed this crackling sound and a metal vibrating sound from my left speakers. Whenever in a music goes from high pitch to low pitch this issue is seen. Also whenever i watch any live show my left speaker just behave weirdly. I recently got another MacBook air for my office and have the same issue hence its definitely a factory defect problem i guess. The vibration sound is so weird like some terrible speaker on a high base sound.

Is there anyone else who is facing such issue?