Psychiatrists can detect precise mood changes, such as a 50% improvement in depression, from a patient's voice tone.

“In many cases in psychiatry, sometimes it's over the phone that you have to make key decisions. And as I recall, vividly being as a resident, very often you have to take these phone calls from people who are not in the hospital, people you can't see, you can't see their eyes, you can't see their body or anything about them, just the sound of their voice. And you can ask them questions, and you have to make, in some cases, life or death decisions. Is this person truly suicidal? Something like that, as it comes up all the time.”