An oscilloscope draws waveforms on a screen so you can see the sound, you can get pro oscilloscopes to do precise measurements and proper science:
Or you can make your own with ean old CRT telly:
CRT stands for “Cathode ray tube” these are the old type of TVs that use an electron beam (or 3 for colour TVs) that is deflected by a magnetic field. The beam scans across the screen really fast and draws the image. But if you replace the circuit that scans the beam across the screen, with an amplified audio signal, you get this:
My oscilloscopes are all made with TVs and although they look kind of cool, they cant really be used to do any kind of accurate measurements. The waveforms it draws arent really correct. This is cool though:
And finally a word of warning. there are a lot of tutorials on how to make your wn oscilloscopes out there. But be carefull!. There are capacitors inside the TV that store 2x the mains voltage and kan remain charged for days after the TV is unplugged. Thats 440V in Norway and that is very dangerous.