Smartphone that feels your strain

WHAT really winds you up every day? Traffic on your commute? A frustrating boss? Or maybe something more subtle that you can't quite put your finger on... Your smartphone may soon be able to tell you where you encounter the most stress, thanks to the development of software that can recognise stress from the patterns in your voice. Called StressSense, the system is first trained to recognise someone's unstressed voice. To do so, the person must relax and read a 3-minute passage from a book, say, into their phone. StressSense then compares this recording to its preprogrammed knowledge of the physiological changes that stress induces, such as a faster speaking rate and a clipped frequency spectrum, and logs any instances of stress it detects. "Our stress model also adapts to different background noise environments," says Hong Lu of Intel in Santa Clara, California, who developed the system. In tests that included putting volunteers through mock job interviews, Lu's team found their prototype's stress-recognition accuracy is 81 per cent indoors and 76 per cent outdoors, where sound quality isn't as good. The team plan to make the system a plug-in to an Android app called BeWell, which uses a phone's accelerometers and GPS sensors to record people's activity and sleep levels. People will be able to set StressSense to either listen to their voice throughout the day, or to only activate when they are having a phone conversation. Lu says he hopes the software will boost awareness of everyday stressful events and help us cope. He will present StressSense at the Ubicomp conference in Pittsburgh, Pennsylvania, next month.