extracting audio from .mp4 file with repeating sound

i am using windows 8 and audacity 2.2.2 with latest version of ffmpeg 2.2.2 and lame v3.99.3 but now when i extract audio from video (.mp4), it extracts it with repeating sound (echo). could you please help to solve the problem.

The current version of Audacity is 2.3.1: https://www.audacityteam.org/download/windows/