I'm not sure when or where this invention comes from, until I saw this ringtone advertisement in MT here ^_^'
Well, a ringtone that has no sound?
No, it's the ringtone which only certain people can hear it.
Yet, many (I guess mostly) internet advertisementS proudly proclaim: "The Ringtone That Adults (age 30+) Cannot Hear!"
In it, it states scientifically that as humans ages, their hearing level also decrease. At the same time, this silent ringtone has a high frequency decibels, similar to mosquito or any other animals that use similar-pitched voice for hunting and detecting its surroundings.
Yet, I wonder, what benefits does this invention has? Is it a new step to advance ringtone tech, or just a novelty creation, or another destructive toy?