The United States Patent Office has a patent, #6470214, (which you can view yourself HERE) whose assignee is the United States Air Force, calling for the “Method and device for implementing the radio frequency hearing effect”.

Under the main heading we see this cryptic sentence:

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

It’s synopsis reads:

“A modulation process with a fully suppressed carrier and input preprocessor filtering to produce an encoded output; for amplitude modulation (AM) and audio speech preprocessor filtering, intelligible subjective sound is produced when the encoded signal is demodulatedusing the RF Hearing Effect. Suitable forms of carrier suppressed modulation include single sideband (SSB) and carrier suppressed amplitude modulation (CSAM), with both sidebands present….enabling intelligible speech to be perceived by the brain…