i don't think there is a way to do this from the command line!
why cli? it rather sound like a job you should start up a (graphical)
DAW for. or was the cli requirement only for the recording not this
particular edit/filtering task?
anyway the only way to get it done quickly, just mute your voice during
recording.. (hope you were not conversing at the same time as others in
the background) - Maybe ecasound allows to assign on/off location
markers during recording. I never checked.
If you speak at the same time with others it's gets tricky. If the
voices have a different pitch (fi. your "old sound" being an allusion to
baby-crying in the background) you can reduce the presence of a
particular voice with EQing + compression. I don't think there is
software out there to automate the task. - audacity might come in handy.
if you want to get into cli denoising based on a audio-sample: