Here they are sticky speakers,
SpaceResonance 141987-697 Square Wave 14198-7697 Hz
141987-697 Hz is beyond the audio range but as a 14.1987697 kHz square wave it has integer multiple harmonics including 141987-697 Hz.
SpaceResonance141987-697 14198-7697 Hz
SpaceResonance141987-697 1419-87 Hz
Do not use headphones to listen to these frequencies. There are strictly for coils, heating elements, antennae and maybe speakers only.
Do not puncture your ear drum. Do not send a beam into your ears. Do not point the beam at shelves, walls, trees, etc. Otherwise, have fun.
