Definitive answer - depends on how loud you listen, and how loud the ambient noise around you is.
Do they leak - yes. Is it excessive - no, but depends on volume of the IEMs.
My daughter noticed mine within 4-6 feet, but couldn't recognise the song until she was beside me. Past 6 feet it was not really noticeable for her. She's 11 and has ears like her mother (can hear a cat walking on carpet) ..... annoying at times - I get the usual "what's that sound?" from both of them and often have no idea of what they are talking about
.
If you need a high level of isolation either way - then these are not the earphones for you.
But you will be missing out on a great sonic signature