I'm deaf on one side, so issues like this tend to be topics that I've already given a lot of thought to. A counter I employ to the cocktail-party effect is to

I'm deaf on one side, so issues like this tend to be topics that I've already given a lot of thought to. A counter I employ to the cocktail-party effect is to pitch my voice very low. Sometimes the person I'm talking to picks up on this (consciously or not!) and imitates my low pitch. Despite others talking over us, it's easier to focus in on a lower pitch and let the brain filter out the noise.