Hello, This is more of a scientific question that support with the actual device. I need to find out the detection distance of the device for the spider monkeys that I am studying. This is much more complicated than I first thought as the detection distance will vary based on not only distance and height (which is easy to test) but it will vary based on the loudness (dB) of the call and frequency. So I have to test several different calls of varying dB and frequency. What I think I need to do is to play different calls of the monkeys into the speakers at different heights, distances and dB levels however I dont know the dB of the speakers or spider monkeys. I did find that some speakers state their dB level and watt which has a rough conversion but I dont know if this is something I can use. Does anyone know if there is a reliable conversion from watt to dB or another way to know this? Or does anyone know how I measure the dB and frequency of prerecorded spider monkey calls, or maybe I cannot even use prerecorded calls? I also found a paper on measuring detection distances but they dont account for any of these questions as they never actually discuss the sound used. If anyone has any advice on this or has solved these issues already any advice would be much appreciated! Thank you. Jenna
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This is quite complex issue and it is very difficult to answer it comprehensively in a simple post. To measure the loudness of the calls you would need to use a calibrated microphone at a specific distance from the monkey - typically a distance of 1m is used. You could then calculate the loudness at greater distance on the basis of quartering the loudness for each doubling of distance and then making some allowance for atmospheric attenuation. You would then need to compare this to the sensitivity of the audio moth. Alternatively a more pragmatic approach is to record from a 'known' spider monkey and keep moving further away (in discrete distances, say 10m a time) until you can't detect the monkey any more. Then plot a graph of the amplitude against distance. You could use a loudspeaker but you would need to record that next to a real monkey to work out when the speaker loudness was comparable to the real monkey at a certain distance.