Purchased for a 3 year old boy who is about 3 feet 9inches tall, and 50 pounds - this costume fit him perfectly, and he will have lots of room to grow length wise I can see this fitting him until 5 for sure maybe 6. I would say he has about 5 more inches in height and 3 more inches in arm length for costume to fit at its best.
The costume itself says for ages 5-7 which is the standard child's size I would say if your child is 9 or older get the Adult size forsure.
As for the "sound" I don't know what I was hoping for ... but I was thinking it was motion activated like when it can sense motion it would roar and what not, but you actually have to push a button to activate it, and it's a tiny square sound box that has a compartment that fits right into the glove area, I paid an extra $10 just for that feature so was hoping for a little more wow factor but it's fine. He enjoys pushing the button and making his own mouth dino sounds. Overall if I could rebuy it I would prefer this sound option over no sound option because it's fun for my 3 year old to push the button and do the dino noises. But as an adult I would just use my phone to be hands free, this would be too hard for a toddler to think of to do.
The most confusing part about putting the costume on was figuring out how the head fits through the hole, so there's 2 openings, the first opening is super stretchy and tight, that part actually goes over the head completely and hugs the neck, my toddler was a little freaked because he was feeling like he couldn't breathe or see, until we figured that out, the part where you see the actual face is just a draw string opening, I would recommend tying a knot once getting it adjusted right on the face or else it will loosen with movement. The neck part was also very hard kind of to get over my toddlers head, if your kid has a really big head I would recommend trying to stretch the neck part out over a basketball or something, and if your child's head is larger then a basketball it's more then likely not going to fit with out cutting the costume and you risk deflation, so just get the adult size.
My final thoughts is that the costume is amazingly adorable, funny and quarky! You will not regret this buy if it fits perfectly for your dino lover hoped this review helped! ❤️