Audio Engineering: Speaker Phone/Stereo Mix Recording Issue

Speaker Phone/Stereo Mix Recording Issue

Here’s the problem: A stereo mixdown recording was made of the guest on left channel and the host on right channel.  The recordist captured the guest via a microphone held to a speakerphone.  The guest was also on a speakerphone, causing the host voice to bleed back to the host-end speaker phone.


  • Host and guest tracks recorded to a stereo mix.
  • Guest on speakerphone and host recording guest using speakerphone (i.e., mic actually placed next to the speakerphone to record the guest).
[player id=6721]




  • Using iZoptope RX6, applied “suppress early reflections” effect (about -12dB reduction) to copies of the original tracks (separated into two mono tracks, one for host and one for guest).  Rendered these as “output reverb only” versions of the original tracks, meaning, only the reverb reflections (the stuff not wanted) appear in the track.
  • Repeated this process for each of the original tracks:
    • Added this “output reverb only” track to DAW, duplicated it and inverted the second track to allow for phase cancellation (When the these two tracks played together, there is no sound).
    • When playing all three tracks together (original + reverb track + inverted reverb track) the unwanted reverb in the original track gets greatly reduced via phase cancellation from one or a combination of the reverb tracks.  (This is the same principle of phase cancellation used in mid-side stereo techniques).
    • Adjusted the level of the original track for clearest, most natural sounding outcome.
    • Created a new single mixdown track for the host and guest tracks (i.e., mixed down the 3 tracks for the host audio, mixed down the 3 tracks for the guest audio).
    • Ducked the “fixed” host and guest tracks and applied some compression and normalization to each track just to even out their levels a bit.

As you can hear, this is not perfect because the original phase issues are baked into the original tracks, but this a big improvement.

[player id=6723]