How do Audio Spotlight products work?

The ultrasound has wavelengths only a few millimeters long, which are much smaller than the source, and therefore naturally travel in an extremely narrow beam. Of course, the ultrasound, which contains frequencies far outside our range of hearing, is completely inaudible. But as the ultrasonic beam travels through the air, the inherent properties of the air cause the ultrasound to change shape in a predictable way. This gives rise to frequency components in the audible band, which can be accurately predicted, and therefore precisely controlled. By generating the correct ultrasonic signal, we can create, within the air itself, essentially any sound desired.

Note that the source of sound is not the physical device you see, but the invisible beam of ultrasound, which can be many meters long. This new sound source, while invisible, is very large compared to the audio wavelengths it's generating. So the resulting audio is now extremely directional, just like a beam of light.

Often incorrectly attributed to so-called "Tartini tones", the technique of using high-frequency waves to generate low-frequency signals was pioneered over forty years ago. Over the past two decades, many others have attempted – and failed – to use this technique to make a practical audio source.

See the Audio Spotlight Products here