You can cut the sound from a video file using our website.
First you need to open Online Audio Cutter.
Sound from a Video File on Your Computer
To extract the sound from a video you have stored on your hard drive, you need to click “Open file” and select your video. The file will be uploaded to our server; the audio track will be extracted and open for you to cut the desired interval. The maximum file size is 4 Gb. 
Once the video is uploaded, you will be able to cut an audio segment from it.