Our daughter first flew in a helicopter when she was just one year old, in a Bell 212. She was already used to fixed wing and a suitable set of ear defenders was not a problem, following a bit of fun play wearing them around the house. Don't deny your family the memories down the track, take your kid(s) along whenever you can as they do remember with a few photos in later years
After
BigMike 's comment about landing, I did learn a lesson a few years later when she was in the back alone and had a major meltdown when she dropped a packet of Cheezles on the floor. Farmer's paddock landing, mate in the front hopped out and retrieved the snack, off we went again