Shouldn't the sound for when a task finishes be something like "Job done!"? Looking at the table it seems like it makes the sound for acknowledging that it's received an order (e.g. "I can do that").
You're thinking of peasants, the Human unit.
`peon --pack peasant`
This was my first thought too, thankfully they thought of it!
Work complete
If we're being strict to peons, then no, that's the human's voice - https://www.youtube.com/watch?v=5r06heQ5HsI.