Safety of High-Intensity Ultrasound

Ultrasound mid-air haptics requires exceptional sound pressure levels (SPL) (>145 dB) to produce perceptible haptic feedback. However, the effects of exposure to such high SPL on humans/animals are not fully understood. Existing exposure guidelines are based on limited outdated studies and additional uncertainties stem from the lack of standards concerning ultrasound acoustic measurements. Yet, in order for ultrasound-based technologies to breakthrough into mainstream consumer products, a safety record needs to be established. This chapter begins with a critical summary of the existing safety data and international guidelines and continues with a report of several recent research endeavours to investigate health-related effects of ultrasound exposure. These include experiments concerning audiological effects, skin and eye exposure to mid-air haptics feedback and investigations into the effectiveness of common types of ear defenders at attenuating ultrasound. While humans may not be able to hear ultrasound, many animals, including common household pets, can. This chapter includes a summary of key concerns with respect to animal safety. Although future work will be required, it is hoped that the information in this chapter will help steer HCI developers to produce designs that are both innovative and safe.