Chirper
Send secret messages in Morse code at pitches that some people can hear and others can't. High-frequency hearing tends to decline with age, so a younger listener may hear a message that an older listener cannot.
High pitches may not play clearly on all devices. Works best with speakers. Start at a low volume.
Frequency & volume
Often audible to adults
Hz
Hearing range presets Tap to set frequency
Approximate tendencies, not fixed age cutoffs. Hearing, volume and speakers affect what you can hear.
Listen to a steady tone at this pitch.
Manual Morse key
Short for a dot. Hold for a dash.
Morse code reference
A dash lasts three dots. Pause three dots between letters, seven between words.