The Sort by Name and Sort By Category commands are found upon the Context Sensitive Menu in both the Tree View and the Table View.
In the Tree View the sort options are accessed via the Context Sensitive Menu for the Collection that you wish to sort (e.g. the Voice Collection to sort Voices).
In the Table View the sort options are accessed via the Context Sensitive Menu for any Object. The sort can also be initiated by clicking in the Name or the Category column headers.