How to find out if the speakers are 20khz compatible? + need to be a native speaker?

[4Kingdoms]

How can I find out if the built-in speakers of my laptop and my mobile phone (A5, 2017) are 20kHz compatible? Because in the night I want to hear with them the ultrasonic subliminals.

Download this program onto your laptop to test your speakers.
http://www.subliminal-shop.com/product/speaker-test/

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Download FrequenSee - Spectrum Analyzer to your phone and watch it at the same time you are testing your speakers.

iPhone
https://apps.apple.com/us/app/frequensee...d583945921

Android
https://play.google.com/store/apps/detai...e&hl=en_US