Hi there,
A little bit a strange question here.
Has anyone got information of the sound frequencies and amplitude output from T200 thrusters?
Would I be correct in assuming that given the max RPM of the thrusters is no higher than 4000RPM that the max acoustic frequency would be ~66Hz?
Obviously the amplitude would need to be measured by a dB meter.
Cheers,
Fraser
A full revolution of the thruster isn’t the only source of oscillation, so sounds can be quite a bit higher pitched than just 66Hz. Since the Blue Robotics Low-Light Camera has a speaker built in, for a sense of the general ranges of sound you can expect I’d suggest listening to some dive logs, e.g. this one from @btrue has a video where the operating sounds are quite prominent.
If you need specific frequencies then I’d suggest either putting a sound measurement device (or phone with suitable app) near your computer speaker while playing a suitable clip, or you can download a video and extract the sound from it, and use some code to run a Fourier Transform on the sound waves and get a frequency histogram.
For actual amplitude data you’ll need to measure that, or find someone with the appropriate equipment who’s willing to do so for you. Are you after sound levels from inside or outside the water? (e.g. are you concerned about scaring fish/submarines, or annoying humans at the surface?).
This is a fair point.
The concern is actually annoying bats in a tunnel with an ASV that uses Blue Robotics thrusters. I have the ability to test with the actual equipment, though I would have thought a phone microphone would not be sensitive to the frequencies that bats echo-locate with (usually above 20kHz). The dB meters I looked into didn’t specify responses above this range.
Given that this frequency is quite high its probably safe to assume the thrusters do get close to this. The concern would only then be if the amplitude of lower frequency sounds was of an amplitude that would annoy the bats.