Can you spot a terrorist by the sound of his voice? Some airport authorities believe the answer may be yes. Passengers at Moscow’s Domodedovo International Airport recently went through an unusual security screening—the GK-1 security kiosk. The GK-1 is a voice-analysis device that was developed by the Israeli firm Nemesysco to separate the ill-meaning from the innocent.

In a procedure that takes less than a minute, passengers answer questions into a microphone such as, “What is your name?” and, “Do you intend to harm anyone on this plane?” By distinguishing between different emotional responses, the system singles out suspicious people who then go through additional computer questioning or meet with security personnel.

Similar security kiosks will be tested at Miami International Airport this year. Which means flyers had better watch their tone of voice next time they get held up in long airport lines.

Nonna Gorilovskaya is a writer based in Washington,...