Meet the SIREN ring: a smart wearable device that serves as your personal alarm to help you get out of dangerous situations. When activated, the ring emits a 110+ decibel alarm to deter those who might be thinking about bothering you. There is a 1.5 seconds of delay to allow you to cancel the alarm in case of accidental activation.
As you can hear in the above videos, the sound is unpleasant, so it can keep people from bothering you. You can find out more information about the product here.