Its amasing the questions you guys are able to come up with...<br /><br />215db <br />SPACE SHUTTLE LAUNCH EXHAUST, APPROXIMATELY 3 MILES PER SECOND<br /><br />Just try not to get too close...consider that it can get just a little bit breasy. Here is a demo from bigger machine with smaller engines:<br />
http://www.youtube.com/watch?v=1CPo_6L0ABk<br /><br />"The decibel unit is commonly used in acoustics to quantify sound levels relative to some 0 dB reference. Commonly, sound intensities are specified as a sound pressure level (SPL) relative to 20 micropascals (20 µPa) in gases and 1 µPa in other media (standardized in ANSI S1.1-1994).[1] 20 µPa corresponds to the threshold of human hearing (roughly the sound of a mosquito flying 3 m away). Often, the unit dB(SPL) is used, implying the standard reference, though this is discouraged by the Acoustical Society of America, which recommends explicitly stating the reference level for each measurement; "100 dB re 20 µPa". [2][3]. In the remainder of this section, the reference level of 20 µPa is implied.<br />A reason for using the decibel is that the ear is capable of detecting a very large range of sound pressures. The ratio of the sound pressure that causes permanent damage from short exposure to the limit that (undamaged) ears can hear is above a million. Because the power in a sound wave is proportional to the square of the pressure, the ratio of the maximum power to the minimum power is above one (short scale) trillion. To deal with such a range, logarithmic units are useful: the log of a trillion is 12, so this ratio represents a difference of 120 dB.<br />Psychologists have debated whether loudness perception is better described as roughly logarithmic (see the Weber-Fechner law) or as a power law (see Stevens' power law), where the latter is now generally more accepted. A consequence of either model is that a volume control dial on a typical audio amplifi