If you want to do something nice for them, you can buy some very inexpensive noise reduction headphones for $25 or so. Found some at Walgreens last year and they seem to work almost as good as $100-$150 ones we have purchased in the past. Give them each one extra battery though, because they will leave them turned on during their stay in Europe and they will be dead. They still work, but not noise reduction with dead battery.