SomethingUnreal | Ultrasound and Slow-Motion Recordings of Dojikko @SomethingUnreal | Uploaded 11 years ago | Updated 12 hours ago
The ultrasonic pulses that let Dojikko "see" her surroundings are normally inaudible to humans, but now, you can hear in detail exactly what's going on. The ultrasound is 40 KHz, about double the highest frequency that most people can hear. When slowed down, not only can you hear the transmitted pulses, but the echoes and the delay between them are clearly audible, too!

I recorded the sound at a very high sample rate (192 kHz - at this rate, the microphones can hear frequencies up to 96 KHz). Afterwards, I slowed down the sound to a quarter of the original speed, 1/8th, 1/16th, etc, even down to 1/128th (at that speed, just 2 seconds would be over 4 minutes long). I also recorded video in slow-motion, but my camcorder can only go up to 200 FPS (1/8th speed when played back at the usual 25 FPS), meaning that lower speeds such as 1/64th aren't smooth, as I had to futher slow down the video in editing. But the main point of this video is the sound.