jremington:
Would there be a method to measure the amplitude?
Yes, use an ADC to measure the signal and characterize the pulse by processing the resulting data.
We would need to be able to set the output in decibels and measure in decibels the returning echo. Any sensor able to do it?
Not to my knowledge. How would the sensor know what an "echo" is?
Good question. I don't know the answer but it is possible in medical ultrasound devices. This is how we have gray-scale imaging. When an object is reflective, it is white. When it doesn't generate an echo, it is black. If only a proportion of the initial transmitted wave is reflected back, then we have a shade of grey.