I think each cat purrs according to their personality. Maybe?

Our tabby girl, Hermione, purrs so loud! She also loves to be loved and loves to cuddle next to me or David.

Noah only purrs when he is asking for love or sleeping on my head.

Phoebe is like your Gizmo...she purrs when she see's me or when I call her name.

Sampson only purrs like Noah, when its love time.

Noel doesn't purr all that much...only when she's in a lovey dovey mood.

Basie purrs a little...mainly when its just him and I together. He'll immediately stop if another cat comes around.

Micah has a soft purr that comes from deep inside him. He purr only during love sessions as well.

Livvy purrs like Noah and Sampson.