but a little bit angry. It was the first time these sound waves had been extracted and made audible. So what's going on here?

Loudspeakers work by converting electrical energy into kinetic energy. This vibrates the cone which creates the sound waves. Sound waves can reflect off surfaces. We hear reflected sound as an echo.

A man’s bass tone, which may be frightening, is raised to a higher pitch to sound softer. However, if an operator cannot tell if a customer is angry, the operator may not be able to react ...

Crucially, the sound waves — specifically, ultrasound waves — used to create the audible enclaves can't be heard along the path they travel and can even be bent to avoid obstacles. Only when ...