This article is part of the On Tech newsletter. You can sign up here to receive it weekdays.

If Amazon’s Alexa thinks you sound sad, should it suggest that you buy a gallon of ice cream?

Joseph Turow says absolutely no way. Dr. Turow, a professor at the Annenberg School for Communication at the University of Pennsylvania, researched technologies like Alexa for his new book, “The Voice Catchers.” He came away convinced that companies should be barred from analyzing what we say and how we sound to recommend products or personalize advertising messages.