Envelope Follower or Ducker?

I’ve been trying to get an understanding of Envelope Followers and Duckers for an effect I would like to try and hopefully program.
I would like to have a music (foreground) and have speech (background) that is always X (lets -15db) below the foreground music. I think duckers are used just the opposite, where people generally want the music to lower but I want the speech to stay lower than the music.

I found that getting an average of both, then reducing the speech is insufficient as I want the speech to follow the volume of the foreground music but always be X decibels below. When I measure the speech in small segments, the speech breaks through the ceiling of X decibels.

How would I go about getting the desired effect? I gather that I will need to have music that has little silence to make this work but beyond that, I haven’t been able to determine how to achieve this effect. The two technologies of envelope following and ducking seems to be the closest to what I desire but I’m having challenges understanding these ideas in the context of my goal. Which is the direction that makes the most sense?

Usually people duck the music with the voice, but you can duck the voice with the music if you want.

Audacity has a native Autoduck, alternatively Steve made a “dynamic mirror” plugin which can duck or follow.

Are you trying to do the Peter Frampton thing?


You could create that effect and then overlay that with the original music track.

Let’s see…that’s Effect> Vocoder.

I don’t remember where I got it from…



I think Ring Modulator can do that.



Then envelope-follower it is …

''dynamic mirror'' (envelope follower).gif
Then adjust the gain-sliders on the tracks so there is an X dB difference between the tracks.

I’ve been going over this and I think after tinkering with mirroring and ducking, that ducking is what I need.
The gain slider was also exactly what I needed to experiment with the outcome.

I’m not sure I understand the difference between the ducking feature and autoducking, as both seemed to do the same thing.

Thank you.

I tried the vocoder because I’ve been interested in that feature for a while but I cant seem effect music.
I tried to modify music so that it essentially modulated a song, not just a note or chord.
I’m wondering if that would be more in the realm of a ring modulator. I’ll have to experiment more to determine what is closer.

realm of a ring modulator.

The Ring Modulator also known as a Linear Multiplier smashes the two sounds together such that the product of the two sounds survives but not either of the two originals. As above, that give you the vocal singing guitar (Peter Frampton) and some popular science fiction sounds. Both sounds have to be present for the output to exist. Can’t multiply times zero.


Audacity’s built-in Autoduck only* ducks, the selected track is ducked by the track immediately below it.
So if you change the order of the tracks it has a different effect …

AutoDuck , ''A'' ducked by ''B'', then ''B'' ducked by ''A''.gif
[ * the Dynamic Mirror plugin can duck or follow ].

I have a much clearer understanding now of the autoducker.

I read the description but the one thing that I dont understand is the threshold.
Does that mean that anything below the threshold (in you example -10db) the autoducker will not act on?

Thank you,


The (-10db) threshold relates to the (control) track doing the ducking, not the track to be ducked.
It will duck the upper track when the lower (control) track is louder than threshold ,
No ducking when the control-track is quieter than threshold.