I want to do a recording of radio news with background music which fades in and fades out while I am reading. I don't have proper device, so I decide to enable loopback mode, so that I can record directly from my microphone to audacity, and at the same time play music in the background with VLC. I am using the volume control of the VLC to fade the music out when I am speaking, and I fade it back in when I pause the speaking.

After some experimentation I realized that at the moments when I adjust the volume, there is no smooth fade-in or fade-out of the music, but instead there is some pops or some distortion. After this happens, an unwanted echo appears in the voice recording, which gradually increases as I fade-in and fade-out many times. After a few minutes of recording, the echo may become unbearable. This echo or the fade-in/out distortion are not audible during the recording. There is something on the way the sound is delivered from the audio driver to audacity.

I tried to increase the latency on the microphone (this is not an issue for me) and I think the problem with the echo was reduced, but it still remained in overall.

Would somebody please think of a solution?

  • you have a problem with your driver settings - looks like there is a monitor or listen flag set in the driver settings. Get rid of this so that you are only recording the direct input from the microphone. Also record everything separately - record the voice, then lay the music in on a separate track. Mix to your output.
    – Mark
    Dec 18, 2016 at 11:19

1 Answer 1


Sounds like your machine is simply running out of steam trying to do those tasks simultaneously.

I'd grab a copy of Audacity [freeware]; record the mic channel on its own, drop in your music channel later, then use automation to control the music levels.
Export the result.

I know neither Ubuntu nor Audacity, so I can't give full details.

  • 1
    OP is already using audacity btw
    – user9881
    Dec 14, 2016 at 22:39
  • Wow, yes indeed, there is this function called auto-ducking that automatically adjusts the background music based on a control channel. manual.audacityteam.org/man/auto_duck.html
    – lefterav
    Dec 15, 2016 at 1:21
  • @DoritoStyle - oops, yes. All I can claim is it was a long day ;)
    – Tetsujin
    Dec 15, 2016 at 5:56

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