Tough question – it’s really hard to choose! I think my favourite finding is that our voices can sound so different from moment to moment, that listeners (who are not familiar with a voice) can have a lot of trouble figuring out that two recordings come from the same person and not from two different people. Just imagine you heard two sound clips of a person you don’t know: one where they are just saying different vowels (like “aah aah aah” or “eee eeee”) and the second one where they are laughing. A single voice will sound very different from one recording to the next. I’ve run studies to show eexactly that: if you don’t know the voice, you really can’t work out whether these two recordings have got the voice of only one or two people in it. If you know the person and their voice really well, it’s a different story: you’ll probably be able to recognise them despite their voice sounding so different in the recordings. That’s however when you only have the voice to go on. Usually – and luckily for us given how bad we seem to be at this! – we do however have a face to go with the voice, when we are speaking to someone in person, which makes things easier. And when speaking to someone, we usually also have listened to the whole conversation, so changes in their voice make sense within that context.