This isn't a question, but it's a solution for MacBook Air Echo sound in Microsoft Windows
the problem happens with headphones and earphones when plugged in 3.5 mm output.
Solution Simply:
- Right click on sound icon next to clock & date
- Choose playback devices
- Choose "headphones" then down click "properties"
- Select "level" tab
- Click on "Balance"
- Small window will pop up
- Do as attached image
the echo sound will disappear during video playback whether local or online
Earlier Mac models