I had a dickens of the time trying to find out how to reduce the echo that is left after background noise is removed. However, I didn't give up and after playing with some of the settings, I believe I've figured it out! I'm using Adobe Audition CC (6.0). You'll want to follow the steps below as your method of noise reduction, not after the fact. So we're preventing the echo during noise removal, not getting rid of it...if that makes sense. So start with your original audio with the noise, then...
- Perform the usual procedures of selecting the background noise and sampling it (SHIFT + P)
- Select all the audio (CTRL + A)
- Get ready to apply noise reduction: Effects > Noise Reduction/Restoration > Noise Reduction (process) OR CTRL + SHIFT + P
- In the window that appears, I played around with three settings (see image below):
- Noise Reduction slider (85%)
- Reduce by slider (about 40 dB)
- Under the "Advanced" section (you may have to click on the little triangle/arrow to expand it), the Spectral Decay Rate (10%). It was this final setting that made a HUGE difference!
- Put the audio on loop if it's a short clip and click the play button to hear a sampling of the noise reduction applied.
- Adjust the three settings mentioned above until you have the desired effect.
- Click "Apply".
I hope that helps!!
