@Tobi I am not aware of one on PC from Smokeball App. But see this article re: Smokeball communicates triggering windows system notifications: 

I think this method should generate a notification noise.

For the communicate app on iPhone or Android there will be a system default notification noise for communicate messages received.

There is no notification of tasks being added to Users. I view this as a UX oversight. It is a needed feature. One workaround is to send the user a communicate with the task information, select the “…” on the message, then select create task from the message and assign it to the user. In this way the assignee receives notification of the task through communicate notifications and a trackable task is created. 

It would be helpful if adding a task through communicate caused an update in communicate that the message had been tasked. Also, a reverse workflow with the ability to send a communicate notification from the creation of the task would be useful.