Amazon's Halo wristband: the fitness tracker that listens to your mood

Halo's always-on microphones and requests for body selfies worry privacy campaigners

Amazon is bringing out its first fitness tracker, a wristband called the Halo, which will eavesdrop on its owner to assess if they are happy or sad based on their tone of voice.

A pair of always-on microphones will listen to users, trying to assess their mood and stress levels. After a training period, the band periodically checks in and listens to your speech, categorising it into a number of emotional buckets - such as hopeful, elated or hesitant - and offer an overall view of peak positive and negative periods.