[sorenjan]

This reminds me of the world cup in South Africa, where the spectators used vuvuzelas to make a unique sound that I found hard to endure. I figured it would be easy to use a notch filter to remove it, but I could never find a way to implement it it real or near real time, only as post processing.

[ermir]

I remember the broadcasters also implemented this solution straight into the stream, the TV spectators did not have to do anything.