Can You Hear This High Pitched Sound? Most Young Adults Can
In Philadelphia the city has installed high pitched noise makers that turn on after 10:00 pm to deter teenagers from hanging out there late at night. It's controversial because some think it discriminates against the teens.
The noise can usually only be heard by people who are 25 years-old and younger, since our hearing naturally deteriorates as we age. Some people who are older can still hear it, but generally people much older than 25 won't be able to hear this high frequency.
The picture below is a visual representation of that high pitched noise. That peak my finger is pointing at is the noise.
When we played it in our studio, without radio processing which alters the frequencies of all audio played, I could not hear it at all and Natasha not only heard it but said she felt it, like it was compressing her head.
There's a company that sells the devices that are installed and emit the sound to repel young ruffians.