Ultrasound independent Advisory Group on Non-ionising Radiation (AGNIR) produced a report in 2010, which was published by the UK Health Protection Agency (HPA). This report recommended an exposure limit for the general public to airborne ultrasound sound pressure levels (SPL) of 70 dB (at 20 kHz), and 100 dB (at 25 kHz and above). Ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz (20,000
Frequencies from Planet Ten of the Rings". Saruman is an evil wizard and Lothlórien is a mythical forest which is home to a race of elves. Frequencies from Planet Ten Frequencies from Planet Ten is the debut album by rock band Orange Goblin. It was released in 1997 by Rise Above Records. In 2002 it was reissued as a double CD coupled with their second album, "Time Travelling Blues" (1998). The reissue version contains two bonus tracks, both taken from their Man's Ruin EP, "Nuclear Guru". The latter bonus track is a cover of Black Sabbath's "Hand of Doom". The original Japanese press also