I need to emit a single frequency above human hearing and then convert that sound into audible sound to be heard through a pair of headphones.
This part is the part that is going to sound silly but bear with me.
I need to walk around blindfolded and still be able to comfortably get around without bumping into anything.
My idea is to bounce a ultrasound frequency off of walls and then back to a receiving device (microphone), convert to audible sound so I can hear the reverberation in my headphones. Why do I want to use ultrasonic? I don't want to bother anyone around me with a noisy "gadget" while I'm at the mall testing it. The unit should all be small enough to house in a pair of sunglasses.
I bought an Uncle Milton's Secret Sounds device (cheezy I know) and pulled it apart to expose the electronics. The emitter speaker is too large for me to use. I need something smaller. Any suggestions?
I'm not an electronics engineer. I'm an IT guy. I can solder.
Can you help?