This reminds me of a practical application of such tech that never really made it. A chap had his invention on (Australian) ABC's The New Inventors, 20 years ag

This reminds me of a practical application of such tech that never really made it. A chap had his invention on (Australian) ABC's The New Inventors, 20 years ago, named Emergalert. It could announce the presence of nearby emergency vehicles. It seemed like such an obviously good idea. https://web.archive.org/web/20040923155023/http://www.emergalert.com.au:80/ https://web.archive.org/web/20040923155023/http://www.emerga...