If someone created a flying machine capable of tracking you down by listening for your voice, you might be terrified. But what if you were trapped in ruins after a natural disaster and first responders couldn't locate you? Maybe then a human-seeking drone(无人机)wouldn't be such a terrible idea. That concept is the focus for engineers at Germanys Fraunhofer FKIE Institute, who've built a drone to find people by detecting(探测)human screams.
"The human-seeking drone would be ideal for post-disaster situations, such as earthquakes, hurricanes and wildfires," said Macarena Varela, one of the lead engineers "They could hover over an area that rescue crews have difficulty getting to and locate exactly where people may be trapped."
Locating people by sound presents its share of challenges. An auditory(听觉的) system would need to distinguish human cries from sounds that often happen in nature such as animal calls and wind. It might also need to recognize patterns associated with kicking, clapping or other ways people try to get the attention of rescue teams.
Engineers took those situations into account when building out their concept drone. They recorded themselves screaming, tapping and creating other noises that might be a sign of people in trouble. Then, they analyzed each sound frequency to find common signatures and used those to train artificial intelligence software. They also worked to remove the noise created by the drone and other environmental sounds.
Once the software part was complete, the team placed tiny digital microphones under the drone and used signal processing techniques that enabled them to track where human noises are coming from. The microphones also enhanced the volume and clarity of the speech. So far, they have conducted successful open field experiments, finding that the drone can estimate a victim's location within a few seconds of picking up sound.
Next, they would like to add a higher frequency microphone to a drone to acquire more audio sound signals. The idea is to pick up noises from hundreds of meters away. Varela said. In the real world, victim's location data might one day be sent wirelessly to emergency crews carrying a tablet.
