> you also can’t see VHF or microwave radiation! True, but you can definitely see some frequencies of electromagnetic radiation (light is electromagnetic radia

> you also can’t see VHF or microwave radiation! True, but you can definitely see some frequencies of electromagnetic radiation (light is electromagnetic radiation, just at a very large frequency). A 525 nm green LED is just emitting a signal at a frequency of 571 THz... which you can actually see. On the other hand, 40 kHz sound (ultrasound) and 40 kHz radio signals (LF, see https://en.wikipedia.org/wiki/Low_frequency https://en.wikipedia.org/wiki/Low_frequency) are definitely not on the same spectrum, one being made of changes in air pressure, the other one by an electromagnetic field.