I asked my Signalyze discussion list colleagues what they thought of this idea. Branka Zei PhD, involved in the measurement of vocal expression of emotions for over 10 years, responded that one can determine the degree of stress only relatively i.e. if you know what the person sounds like when not under stress. But one has to distinguish between cognitive and emotional stress. What exactly is measured is hard to say. Certainly not the truth of what someone is saying.
Stress can be present in good or bad situations.
This is why marriage is a strong stress factor. In addition, the way emotions are expressed in the voice depends on the general reactivity of the autonomous nervous system, on cultural habits, and many other things. Briefly, what is measured is the overall pitch height and mean energy. Any further serious analysis would need to take much more time and human intervention. All Agora Newsletters are also archived under the Agora Newsletter item of Agora's top level menu.