I was listening to this 19hz sound for 10 minutes and strangely my eyes started to hurt, maybe some screens emit flicker at this frequency which may cause eyestrain?, another thing I read is that electronic devices use something called "Ultrasonic Cross- Device Tracking", which send ultrasonic sound waves inaudible to humans, but they use them to send information between devices and to know what we are seeing or listening and send this data to apps for their purposes, these ultrasonic sounds can also cause migraines, dizziness or tinnitus to sensitive people.
19hz sound:
https://www.youtube.com/watch?v=6RPABglydG0
Ultrasonic Cross- Device Tracking:
https://www.youtube.com/watch?v=j1FfVK6sj4I