The mosquito tone became widely known in the mid 2000s as a very high pitched sound around 17 kilohertz, inspired by a device used to deter loitering. Because adults gradually lose hearing at that frequency, the tone was shared as a ringtone students could hear but many teachers could not. Clips spread through phones, forums and soundboards, often in Spanish searches like sonido del mosquito, and it remains popular for pranks, hearing tests and jokes about summer pests.