Telephones lie about sounds because odd numbers aren't even. Once again with those integers and sound perception! Telephones can only pick up frequencies above 300 or 400 Hertz (cycles per second, also called Hz), but most adults’ speaking voices are lower than 300 Hz (approximately the D above middle C).
Nature Video finds out how to levitate objects using sound waves. Scientists can float objects in mid-air, using just the power of sound. Now, using ultrasonic speakers, they can levitate things with more control than ever before, moving small objects in three dimensions even with the whole array turned upside down. They have also developed virtual ‘holograms’ to visualise how the shapes made by the sound waves can ‘grab’ objects.This article was reproduced with permission and was first published on Oct 27, 2015. It is a Nature Video production.