When I was researching Active Noise Reduction technology that comes as one of the features of Starck designed Parrot Zik headphones, I have learned about sound which has a negative decibel parameters – dB. Theoretically we should not hear it, however some of us do. The negative decibels are one of the qualities of WiFi i.e.  20MHz -72dB the frequency as well as signal strength varies, however it’s always in -dB range with frequency of 20MHz and 80MHz. That frequency well correlated with GSM signal of 800MHz and there is possibility of interference.

Interesting finding on negative decibel sound from one of the sources:

During the first Gulf War when Saddam Hussein’s primary C2 capabilities were destroyed, his troops were forced to listen to regular FM radio stations for their encoded orders. A US PsyOp unit used this opportunity to install a portable FM broadcast transmitter on top of the highest building in the city of Al-Khafji.

There, they transmitted a high-powered 100 MHz signal to overpower the Iraqi station which was transmitting on the exact same frequency. This programming consisted of patriotic and religious music as well as intentionally contradictory military orders. The broadcast also consisted of inaudible negative Silent Sound programming which allegedly devastated the Iraqi soldiers.

“Although completely silent to the human ear,” reported the British television network ITV News on March 23, 1991, “the negative voice messages … were clearly perceived by the subconscious minds of the Iraqi soldiers and the silent messages completely demoralized them and instilled a perpetual feeling of fear and hopelessness.”