... but 2 voices almost always singing the same note. ....
Right now I'm listening to a conference call and somebody who 'thought' they were on mute just flushed a toilet.
Do two toilets flushing at the same time sound the same? I really should be going back to work but apparently potty humor is entertaining me more at the moment.
In Japan, one can buy a Princess toilet. As soon as you approach, it begins to make babbling brook sounds to disguise, umm, the other sounds. It has several progammable sound options.
I wonder if "screaming" or "hysteria" are choices?