I have an orchestral recording with an audience. In one part of the recording, there are shock chords (loud, short chords played by the whole ensemble) at 0 dB with about two seconds of 'silence' between each. Obviously the silent parts aren't actually silent: they have the usual venue and audience noise, as well as the sound of the shock chord dying away and echoing, so they don't get any quieter than -72 dB.
Some child in the audience found the whole thing quite amusing, and giggles in one of the silences. It's less than -48 dB, but really damages the effect. It's during the quietest part of the silence, and well away from the following shock chord, so it should be easy to remove, but it's giving me trouble. How can I remove this unwanted sound?
I've tried using frequency-based filters, but the giggle is quite broad-spectrum: it's mainly around 50 Hz, right over the background sound, so I lose too much that way.
I've tried running Audacity's "noise removal" effect on the passage, priming it with the background from another silence, set to "isolate" instead of "remove" noise, but even at 48 dB it leaves way too much giggle.
I've also tried pasting a section of one of the adjacent silences, making sure it's the same length and getting the zero-crossings right, but because the echo is slightly different for each chord, it leads to a jarring transition. Each shock chord is the same chord (though the balance between instruments is slightly different), so it seems like it should be possible to make this technique work. Maybe I just need to do something clever with cross-fading to a second track that's a copy of the adjacent silence? How do I make that work in Audacity?