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Patent 6470214
Patent Information:  USPTO Site Listing
Patent Number: 6470214
Patent Title: Method and device for implementing the radio frequency hearing effect

Issue Date: 10/22/2002
Filed Date: 12/13/1996
Serial #: 766687

Assignee Name: The United States of America as represented by the Secretary of the Air (Washington, DC)
Inventor(s): O’Loughlin, James P. , Loree, Diana L.
Lab Information:  View Lab Profile
Lab Name: Air Force TechMatch Patent Lab
Location: 1000 Technology Drive
Fairmont, WV 26554
Contact: Contact Lab About This Patent

Description:
BACKGROUND OF THE INVENTION
This invention relates to the modulating of signals on carriers, which are transmitted
and the signals intelligibly recovered, and more particularly, to the modulation of
speech on a carrier and the intelligible recover of the speech by means of the
Radio Frequency Hearing Effect.
The Radio Frequency (“RF”) Hearing Effect was first noticed during World War II as
a subjective “click” produced by a pulsed radar signal when the transmitted power
is above a “threshold” level. Below the threshold level, the click cannot be heard.
The discovery of the Radio Frequency Hearing Effect suggested that a pulsed RF
carrier could be encoded with an amplitude modulated (“AM”) envelope. In one
approach to pulsed carrier modulation, it was assumed that the “click” of the pulsed
carrier was similar to a data sample and could be used to synthesize both simple
and complex tones such as speech. Although  . . . . More
Abstract:
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 demodulated using the RF Hearing Effect. Suitable forms of
carrier suppressed modulation include single sideband (SSB) and carrier
suppressed amplitude modulation (CSAM), with both sidebands present.
Claims:
What is claimed is:
1. A method of encoding an input audio signal a(t) to produce a double sideband
output signal having a .omega..sub.c carrier frequency, which when transmitted to
the head of a receiving subject, will by the radio frequency hearing effect induce a
thermal-acoustic signal in the bone/tissue material of the head that replicates the
input audio signal and is conducted by the bone/tissue structure of the head to the
inner ear where it is demodulated by the normal processes of the cochlea and
converted to nerve signals which are sent to the brain, thereby enabling intelligible
speech to be perceived by the brain as any other nerve signal from the cochlea, the
method comprising:
applying an input audio signal a(t) to an audio pre-distortion filter with an As(f) filter
function to produce a first output signal a(t)As(f);
adding a very low frequency bias A to the first output signal to produce a s . . . .
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