How to Remove an Echo in Audacityby Scott Shpak ; Updated September 22, 2017
Unwanted echo and reverb on audio recordings occur when sound reflects off walls, floors and ceilings with enough strength to be picked up by the microphone. Completely removing these effects from a recording is impossible, but freeware audio editor Audacity has some tools that may help you reduce the effects of these sound reflections, the most effective usually being a noise gate, which allows you to control echo, reverb and other noise between segments of important audio.
Download and install the noise gate plug-in provided through the Audacity website, if you do not see "Noise Gate" listed under "Effect" on the toolbar. You may need to restart Audacity after installing the plug-in before it appears on the menu.
Open the audio file with the echo you wish to reduce in Audacity. Click "Effect" on the toolbar and select "Noise Gate" from the list. The noise gate window is an offline effect, meaning that it will process your audio before you play it back to hear the effect.
Set the controls of noise gate to remove echo and other unwanted noise content. Start with "Level reduction" at -100, "Gate threshold" at 30 and "Attack/Decay" at 75. Level reduction tells the gate how much to reduce unwanted audio. The gate threshold sets the volume level at which the gate starts to reduce sounds and the attack and decay setting affects how quickly the gate process starts and stops. Click "OK" to start the process.
Play the result of the noise gate process. Evaluate the effect of those settings. If there is no change to the echo, increase the threshold setting until the echo occurring after important audio is sufficiently reduced. Reduce the threshold setting if the noise gate cuts off important audio. This process may take several attempts. Click "Edit" from the toolbar, then "Undo" to restore your audio to its original state between attempts.
Adjust the level reduction and attack/decay settings to make the noise gate effect more natural, after you find an effective threshold level. Increasing level reduction adds some echo, but you can control what level. Increasing the attack and decay time smooths out how the gate effect begins and ends. Slower settings make the effect less noticeable.
Work on copies of your original file to prevent loss of data if you accidentally over-process your audio.