3 ms·
The context is building a robot for a sumo competition in university. By this time I am towards the end of my Phd, and regular strategies don't cut it anymore.
by 317070 5y ago
The context is building a robot for a sumo competition in university. By this time I am towards the end of my Phd, and regular strategies don't cut it anymore. We want to show off.
Since many of these robots use ultrasound locators based on echolocation to find other robots, we want to eliminate those from detecting us. One of the strategies we wanted to try, was to generate sound at the right frequency ourselves, which should completely ruin those sensors, thus making us invisible for no apparent reason.
So I bought a transducer used to clean ships, which was rated for use around the correct frequency. I connected it to a signal generator at an ultrasound frequency and wanted to test its effect on the echo sensor.
Now, I am doing this sitting in a noisy lab with a bunch of noisy instruments, robots whirring and computer fans. Some other people in a corner chatting away.
I put the transducer in front of the distance sensor, set up the program to print the distance measured, turn on the signal generator, and the whole room goes eerie silent.
I turn it off, and luckily the sound comes back immediately. It appears that if you pump 100+ decibels of ultrasound in a room, it actually drowns out other noise! This thing was quite powerful. After all, it was made for cleaning ships from foul.
At that point, I do realise I have no idea whether this is a safe thing to do for my hearing (and that of the audience), and shelve the idea. But I remember the split second where I thought I made myself and everyone else in the room deaf.
- mcjkrw 5y agoDid it affect the other people in the room, or were they too far away from it?
- 317070 5y agoIt affected everyone in the room and to a lesser extent the next rooms over if the door was open. Obviously, we did not shelve it right away since there seemed to be no permanent effect. Some people were really creeped out after they had been exposed in my first try. But this is an engineering lab, so soon enough the lab was filled with cowboys wanting to experience it and trying to figure out how it works. Meanwhile, the more safety minded people took a short break and went for some air outside. We stopped after the professor figured out something odd was going on on his floor.
- mcjkrw 5y agoSounds like fun. I had no idea something like that was possible.
- bellyfullofbac 5y agoI wonder what the physics behind it is. I guess if you have an aquarium of water with low frequency waves and overwhelm it with high frequency waves, you wouldn't be able to see the low frequency ones any more. Presumably (IANA physicist) it's the same thing but with sound waves.
- moralestapia 5y agoVery nice story, if only it were true. Let's hope your PhD wasn't imaginary either, cue "science reproducibility crisis".
- 317070 5y agoWhy? Because different frequencies are linearly independent and shouldn't affect eachother? That is only true for linear systems. I am not sure what causes the other sounds to sound dampened, I figured it had something to do with how the ear works, that the sounds were physically still there. But it is easy enough to try. Get a speaker or transducer rated for ultrasonic frequencies, and pump it with enough power that would make a real speaker sound painfully loud.