Below is video tutorial about how to make a device to hear through the wall. or called Spy Stethoscope. To make this device we only need a stethoscope and multimedia microphone. Using this device, we can heard a sound that could not be heard.
To make this device, first disassemble the microphone then put the microphone into the earpeaces of the stetoscope. Second, plug the microphone into mini stereo adapter. And the last steps, connect it into a mp3 player or other record device. Now you ready to record what you heard.