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Spread Sheet: How far away can this gun be heard?

In another thread we were discussing something which suggested I should make this spread sheet.

Simply install a sound meter app on your Android phone and fill in the blanks on the sheet. It should do the work for you. Comments are embedded in the sheet for each value.

Here is an image of a sheet I worked up for one of my spring rifles.

NOTICE: In very low noise environments you will get distances which do not seem to make sense. They will seem to be much farther than you would expect. This is because there is no consideration in this spread sheet for reflections, absorption, or Fresnel losses (yes there is such a thing in audio work). This spread sheet assumes FREE SPACE in the calculation, no obstructions, no absorption, no reflection. That is why the numbers appear to be "irrational" when very low noise areas are used as the test environment. Think about how far you can hear things across a body of water. If you want more realistic numbers, numbers which more closely match what you will see in real life, in a cluttered, absorptive environment, set your noise floor average to 55 or 60 dB across the board.

muh-max-range.1652499552.jpg


Here is the second page of the spread sheet with test data filled in. It lets you compare the results of two different noise sources (read moderators).

muh-compare-mods.1652499567.jpg


Here is an XLS spread sheet:



download.png
View attachment max-sound-detect-range.1652499581.xls

High quality, free, no adds, deciMeter for Android: https://play.google.com/store/apps/details?id=com.dom.audioanalyzer&gl=US





NOTE: If you find something wrong with the math, please let me know so that I can correct the sheet.
 
Nice work - here is another free site that would work well for this and adds google map overlays: https://noisetools.net/dbmap/ I've used this one for a few environmental noise studies in the past and it does have a factor you can adjust for ground cover / surface absorption. I haven't gone out and set up a sound source at one spot and taken a measurement at another place on the map to directly check the calculations but it does use ISO-9613 for outdoor sound propagation and seems legit.

That site doesn't calculate if a sound is perceptible or not but you could measure an ambient noise and see at what distance your source attenuates to about 10 dBA or so below the ambient noise level.

You can also trace around buildings and specify heights if you want to bring reflections from structures into the mix.