Most Labradoodles are very quiet dogs and will usually not bark excessively unless they are around strangers such as when you have people come over to your house that the Labradoodle doesn't know.
My moms Labradoodle is very quiet usually when I'm around because he knows me but when strangers come around or when other family comes over that he doesn't know he will bark for awhile until he gets to know them.
However some Labradoodles do have an excessive barking problem and will bark at people outside, animals outside etc.
You can however train the Labradoodle to stop the excessive barking or put a bark collar on the Labradoodle dog to help train them from barking constantly.
Some dogs will also bark constantly when you're not around and may be bothering people as well and you may not even know it.
So a dog that barks constantly needs to be trained to stop the constant barking.