So as I promised, this is a demo of the navigating device for the blind, which is based on SigmaDSP. The device imitates bat's cries and is totally ultrasonic. So the reflections, which you will hear are also ultrasonic, just scaled down into the audible range. The amazing thing is that my friend, for whom I have built this thing, can distinguish fabric from glass and glass from paper! Let alone telling the speed of movement and feeling the space. The flip side is that of course navigating like a bat will take prodigious learning. Years most probably. As a bonus I will also include sound of rain, because surprisingly raindrops, if "kicked" with high-frequency ultrasound also produce Doppler shift, which sounds pretty cool. The last one is sound of real bat's cries, which I recorded with the same device, but when it worked in the "natural human range hearing extender" mode. I found out that we are in general literally surrounded by constant ultrasonic noise!! The device is 2.5X4.8cm in size and the heart is adau1701. I just want to say once again lots and lots of "thank you" for all of you guyz, who helped me with advice and with samples. Thank you and thank you again.
P.S. sorry for the noise there - some is ultrasonic noise from my laptop and the white one - a consequence of a really bad line input of my recorder.