We've made the little app "dBSea-Impactor" that will help you estimate impacts of noisy underwater activities.
(*If you've never installed an app from outside google-play see end of post)
The app is meant to be a useful go-to app for quick assessment of how far away a given species can hear or is deterred from the noise. This information can be used to quickly asses whether mitigation is definitely needed or if the scenario should be investigated further.
The user is allowed to specify the level of the source by entering measured dB-levels in octave bands and providing their distance to the source measured. From this the app calculates source levels for each frequency band.
You can then set the hearing threshold of the species of interest (the app comes with thresholds for four common species around Ireland) and the level above their threshold you deem acceptable. As there is very little scientific evidence available on what constitutes "too noisy" I will leave it to you to find out (check NOAA p. 38 or a good overview at DOSITS). The app applies this level to each octave band, so the finished threshold used to calculate the distance is the hearing threshold plus the "dB above audiogram" level.
The app first uses simple spherical loss for the main attenuation calculation, meaning that at "x" meters from the source the sound pressure level is 20log(x) (-6.02 dB per doubling of range) less than the source level. This works for lower frequencies, but for higher frequencies the attenuation due to absorption becomes more important and this is therefore included in the calculation (As per Francois and Garrison, 1982).
(*If you've never installed an app from outside google-play see end of post)
The app is meant to be a useful go-to app for quick assessment of how far away a given species can hear or is deterred from the noise. This information can be used to quickly asses whether mitigation is definitely needed or if the scenario should be investigated further.
The user is allowed to specify the level of the source by entering measured dB-levels in octave bands and providing their distance to the source measured. From this the app calculates source levels for each frequency band.
You can then set the hearing threshold of the species of interest (the app comes with thresholds for four common species around Ireland) and the level above their threshold you deem acceptable. As there is very little scientific evidence available on what constitutes "too noisy" I will leave it to you to find out (check NOAA p. 38 or a good overview at DOSITS). The app applies this level to each octave band, so the finished threshold used to calculate the distance is the hearing threshold plus the "dB above audiogram" level.
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| The starting screen of dBSea-Impactor, lots of options! |
Now a word of warning - the app is not validated, and will yield results that are not correct, especially for low frequencies, and it is only good for giving you a starting point for further investigation (more measurements or advanced modelling).
If you have the actual source levels (1 m. from the source) just set "source distance" at one metre and the app will treat your "measured levels" as source levels.
We hope you will enjoy using this calculator and that it'll make your life a little bit easier when you're at sea and trying to remember those pesky formulas!
*The file: dBSea-Impaktor.apk is an android installation file. On many phones, to install from outside google-play, you need to go to Settings>Security>Unknown Sources and tick that box. We recommend that you "un-tick" the box after installation to avoid installing potentially harmful software accidentally.
We hope you will enjoy using this calculator and that it'll make your life a little bit easier when you're at sea and trying to remember those pesky formulas!
*The file: dBSea-Impaktor.apk is an android installation file. On many phones, to install from outside google-play, you need to go to Settings>Security>Unknown Sources and tick that box. We recommend that you "un-tick" the box after installation to avoid installing potentially harmful software accidentally.
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