Interfacing ultrasound receivers and emitters with a microprocessor
It's not clear what you are really asking.  Ultrasound receivers are usually piezo microphones, so electrically you process their signal like any other piezo microphone.  The signal you are looking for can be a few 100 &micro;V to a few mV.  Usually you need a voltage gain of 1000-5000 to drive a microcontroller A/D input.

Ultrasound transmitters are usually piezo speakers, so you drive them as such.  Look at the datasheet carefully to see what the maximum voltage is you are allowed to drive the transmitter with.  This can be a few 10s of volts.  Beware that these piezo elements can appear inductive to the driving circuit due to the mechanical intertia driving the piezo element backwards when you stop driving it.  This means they can exhibit what looks like inductive kickback to the driving circuit, even though the actual mechanism is not inductance.  To get the 10s of volts to maximally drive a piezo transmitter could require a boost converter for that purpose, and/or possibly a H bridge to halve the drive circuit voltage requirements.