Excess Attenuation through the Atmosphere

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.