Simple ultrasound mic?

WTPfeffer wrote 12/14/2020 at 15:41 2 points

I'm a new member and not sure if I'm in the right place.... However: 

I want to build a very simple microphone that can detect audio signals up to ca. 45 KHz. All I need to do is detect the wave form.  I want to find out what devices (iPhone, computer, camera, etc) produce noise that seem to be upsetting my dog, but that I can't hear.