Apple could use ultrasonic sound waves to deliver haptic feedback to wearers of its upcoming AR/VR headset when they interact with virtual objects.
Most consumer AR/VR headsets do not provide haptic feedback like that, but some high-end ones feature a basic vibration motor that does not give the desired effect. However, Apple’s new patent filings suggest it wants to solve this issue on its AR/VR headset by using ultrasonic sound waves.

