You know that time when you couldn't concentrate at all because of someone having a phone conversation right next to you? It's the trouble with a halfalogue. Hearing only one side of a conversation, it turns out, can be more distracting than hearing the whole dialogue. This might stem from the unpredictability of the conversation — our brains working overtime to connect the dots and uncertain what's coming next.
Halfalogues were investigated in a paper by Lauren Emberson and coauthors: Overheard Cell-Phone Conversations: When Less Speech Is More Distracting. The distraction potential of halfalogues could have more serious impacts on a driver from a passenger's phone conversation in the back.
A halfalogue is a nice extension of the dialogue and monologue.
Here's a halfalogue sketch by itself
Emberson, Lauren & Lupyan, Gary & Goldstein, Michael & Spivey, Michael. (2010). Overheard Cell-Phone Conversations: When Less Speech Is More Distracting. Psychological science. 21. 1383-8. 10.1177/0956797610382126.