I am hearing an echo or reverberation in my audio when playing on the timeline or produced file.
This is caused by recording both system audio and another source (microphone, stereo mix, etc.) simultaneously. These tracks can get slightly out-of-sync and cause the echo.
Camtasia 2020 and later:
If recording system audio only, make sure System audio on has a green check mark and Microphone off has a red x through it.
If recording your voice (microphone) only, make sure System audio off has a red x through it and Microphone on has a a green check mark.
Camtasia 2019 and earlier:
If recording system audio only, select Record System Audio and Do Not Record Microphone under the Audio On dropdown.
If recording your voice (microphone) only, select your desired microphone and deselect Record System Audio under the Audio On dropdown.
You can also fix existing recordings by deleting one of the audio tracks in the timeline.