There are other instances where listening to lashon hara may not only be allowed but it may be a mitzvah. One example is a situation where one knows that if they allow the individual to say lashon hara they could immediately follow up the gossip with a defense of the individual spoken of.
* In such a case it is the right thing to do to listen to the individual say lashon hara. Another example is if one understands that by allowing an individual to vent, one knows that they can listen and then ensure that the speaker of lashon hara will cease to share the story with others. In such a case it is also a mitzvah since by listening one is ultimately increasing peace. In either case, one is forbidden to believe the lashon hara as fact.
* One can use this tool to retroactively fix lashon hara that was mistakenly listened to. Meaning, if one slips and listens to lashon hara they could erase the sin by trying to find any way possible to excuse the individual being spoken of by suggesting alternate understandings of what happened or arguing on the facts.