Originally posted by humy
That looks really cool!
But I am concerned that it uses ultrasound to create tactile sensation. My concern with that is that the vibration that it could put on the soft tissue of the few people like me who have the extreme form of Reynolds syndrome, which causes amongst other things extreme sensitivity to vibration that causes pain and eventual loss of bloo ...[text shortened]... ame devastating way so perhaps it would be all right for people like me? -does anyone here know?
Funny you should mention that, my son Kevin has the same problem in his feet and hands, but if you saw the video they aimed the vibrations at a plate of water and you could see the surface pushed in a bit but it wasn't an extreme effect, it didn't make the water boil up or anything so I think the feeling would be not strong. You might see if you get effected by an ultrasound imager head, the energy level there is very high compared to what they would be using.
Although the frequency of ultrasound is a lot higher than what I observed in the image, The effect on the water was within a diameter of about 2 cm so it implies a frequency of probably 50 kilohertz or so, 1 hertz of sound has a wavelength of roughly 300 meters so divide that by 50,000 you come up with a wavelength of 6 millimeters or so at that wavelength and it looks like they focus about 3 or 4 wavelengths onto the subject, roughly the size of a fingertip or a bit bigger.
The only way to find out for sure is to stick your finger in the audio field and see if it hurts.
BTW this is an extension of the ultrasonic loudspeaker technology, where you put an audio signal on a speaker that is emitting ultrasonic energy and that sound mixes with the ultrasonic frequency and you hear the audio focused into a tight beam because when you mix signals you get the carrier plus and minus the frequency of the audio modulation but the effect is you only hear the audio since we are insensitive to the high frequency of the ultrasonic energy but it is still there. I wonder if you have ever been in a museum that uses that kind of speaker, it is designed to have a very directed beam so it cannot be heard outside its field so it seems like you are having sound directed to your head only and not to the dude 2 feet away. It's a clever use of ultrasonic energy. If you could put your hand in that field you might recreate the feeling of the ultrasonic phased array unit in the tactile sensor. Maybe not since there was a lot of ultrasound transducers concentrating energy on one spot. Anyway you would have to feel it to decide if it would effect your pain level.