Yes, Bengals are known to be very vocal. When I've seen them at cat shows they're very loud compared to most of the other cats there so I really don't think that this is a medical issue.

Giving them lots of attention and excercise is great. I wonder of they like catnip. If they do then maybe this could help to calm them down a bit. Cats like so many different kinds of toys that it's hard to tell which toy would be best. My cats love the small catnip mice, some of them love balls, anything you can drag around and they can chase is also great. Some cats also love the laser pointer. My Pearl loves to play with straws and my Ziggy loves pipecleaners that I make into spiders so every cat is different. Good luck.