Hold the button. Raise the fence.
This is a real high-frequency tone from your phone speaker — the strongest fence a phone can honestly raise today. Many people under ~25 can hear the lower modes; dogs and cats hear all of it. Real range is a few feet, not 200 — no phone speaker on Earth can push a crowd; that takes energy no pocket device holds.
The full vision — silent to you, 200 feet, one hardware-button press — is Presidential Challenge № 033. Phones also bar apps from the power/volume buttons, which is part of the challenge.
Safety: sound plays only while you hold. Keep it away from ears — yours and animals'. Skip it in hospitals and around hearing aids.
Three real tests, run on this phone. 🎧 HEARING LADDER finds the exact frequency where your ears + this speaker stop — hold the phone near your ear and answer each tone. Run 🎙 MIC ECHO last: while the mic is live, iOS reroutes the speaker and the fence gets weaker — v1.2 resets the audio session after it.
Two real tests, run on this phone. SELF-TEST proves the audio pipeline produces the tone. MIC ECHO is the end-to-end truth: the fence emits, the microphone listens, and we measure what actually came out of the speaker.