Amazon 'human error' let Alexa user to eavesdrop on 1,700 private audio files from another person

Researchers at China's Zhejiang University published a study last year that showed many of the most popular smart speakers and smartphones, equipped with digital assistants, could be easily tricked into being controlled by hackers. They used a technique called DolphinAttack, which translates voice commands into ultrasonic frequencies that are too high for the human ear to recognize. While the commands may go unheard by humans, the low-frequency audio commands can be picked up, recovered and then interpreted by speech recognition systems. The team were able to launch attacks, which are higher than 20kHz, by using less than £2.20 ($3) of equipment which was attached to a Galaxy S6 Edge. They used an external battery, an amplifier, and an ultrasonic transducer.