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Excess Attenuation through the Atmosphere

This calculator requires a JavaScript capable browser

There is additional attenuation of sound through the atmosphere beyond the simple 6dB per doubling of distance we demonstrated previously. The amount of excess attenuation is dependent on humidty, temperature, air pressure and frequency. Here's a calculator for excess atmospheric attenuation built around a JavaScript calculator written by Enviromeasure in the UK. We've added output in the more conventional North American form: excess attenuation in db/100 feet. To the readers in the USA, we're sorry about all the metric input, but this a scientific calculation, and is all based on the SI measurement system, that's just the way it is.

JavaScript Help
This is the air pressure in Pascals (Pa), sea level is 101325 Pa, 101325Pa = 14.7 psi
This is the air temperature in degrees Celsius (20 degrees C is roughly 70 degrees F)
This is the relative humidity in % (same in English and Metric!)
This is the frequency of interest in Hz (i.e. 4,000 )

The data input above should only have numeric values, no letters please!
This is the excess attenuation at the selected frequency, shown here in:
Excess Decibels of Attenuation per kilometre
Excess Decibels of Attenuation per 100 feet

This information is provided with no warranty of its accuracy, or applicability, and any use made of this information is done so at the sole risk of the user.

Mc Squared System Design Group, Inc Mc Squared System Design Group, Inc
323 - 901 West 3rd Street
North Vancouver, BC V7P 3P9
Phone 604 - 986 - 8181