This pattern is written to fit children from 6 months to 3 years. However, the pattern can easily be adjusted to accommodate different sizes. Just make the hat bigger and the center strap longer! Once you read through the pattern, the sizing should make sense.
As a matter of personal preference, the first time I made the hat (and still my favorite version), I knit the hat and crochet the headphones. However, because I know that other people's preferences are not the same as mine, I've written both knit and crochet instructions for both the hat and the headphones.
I'm a SAHM to 3 wonderful children, although I hope to get back to work once they're a bit older... In the meantime, I attempt to have a life outside of my kids by knitting, crocheting, and designing. If nothing else, it provides some much needed relaxation! :-)