I usually deal with outdoor noise propagation (noise impact assessments). I use software like Cadna, Soundplan and Predictor. I'm Interested in bioacoustics (I don't do this for a job) I'd like to know if specific software (free and not) exists to study the noise effects on animals. Sometimes reading noise reports that deal with impacts on animals I noticed that usually a dB(A) is used. Is it correct that a human filter scale can study the noise effects on animals?
For studies aiming to evaluate the signal to noise ratio for acoustic signals, dB is often used as a operational variable. For frog calls the dominant frequency is also commonly used, because females are sensitive in perceiving variations in this trait. I use several sofwares for audio editing and analisys, i.e. Soud Ruler, Adobe Audition, Wave Editor and Raven.
to evaluate a possible impact of noise on animals the A curve is misleading as it is based on the human hearing sensitivity curve. No weighting, or a weighting tailored on the sensitivity curve of the target species should be used instead. However, I strongly suggest to perform full range 1/3 octave analysis and possibly consider the percentile distribution of energy vs frequencies to have an idea of the possible impacts.
Not only "levels" should be considered; the spectral structure of the noise and its distribution in time (e.g. continuous, intermittent, random, ....) are important as well.
A procedure one could do is to turn the relative values of sound pressure given by acoustic softwares into absolute values, by defining the most intensive SP of your sound file (noise or acoustic signal) and the maximum SP registered in the field with a sound level meter, thus: SP absolute= SP relative * SP max / SP most intensive. This procedure has been used in studies evaluating signal-to-noise ratio for the calls of frogs which inhabits noisy streams.
Propagation plays an important role and in the marine environment it is really complex.
The best available free software is ActUp, not easy but powerful:
https://cmst.curtin.edu.au/products/actoolbox.cfm
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