Have you ever thought of teaching your Bird Dog sign language? I don't mean human sign language. I do mean signs like, putting up your hand in a STOP manner. This can be very helpful in the field. Pointing in the direction you'd like your dog to go, or motioning for your dog to come when you don't want to make a noise, are both handy in the field. You can teach them any sign for any command but you must keep it simple. Make sure each signal, or sign, is totally different from the rest. If you teach your dog a sign, along with teaching the voiced command, eventually, you'll be able to drop the voice command.