I've hiked with dogs over the years and encountered black bears on at least 6 occasions. Neither of the two dogs i've had over the span of 25 years acted aggressive during a bear enounter which i think helped me avoid potential problems. Usually when I spot a bear I remain quiet and slowly leave the area. I think a barking dog could be viewed as agressive by a bear and result in an attack.
On one occasion i was out with my dog along with a couple of other dogs when we encountered a cougar on the other side of a creek. The dogs stood on one side of the creek barking and snarling while the cougar stood on the other side hissing and growling. This went on for a few minutes until the dogs won out and the cougar left. So perhaps your app may have some value, just not with bears.