Radio forbidden. Brings world into home: news (anxiety), music (instruments = sin), ads (temptation). Three enemies in one device.
But
English hired hand arrives on tractor (help with heavy work). Tractor has radio. Radio plays country. Amish boys listen (accidentally, of course). Like it (accidentally, of course). Memorize the melody (accidentally, of course). Whistle in the barn (absolutely accidentally).
Rule
Amish doesn't turn on radio. If radio plays nearby — not his choice. Not his sin. Gray zone the width of a tractor.