(Some restrictions apply. You will NOT be the world's first Light Listener because I will:)
Step 1: Get the Parts
Ceramic earphone (I got mine at Mouser along with a lot of other great parts.)
Solar Panel(s) (You can use one or two...I used two because it gave me more surface area. More surface area = more noise!)
Tape or a hot glue gun (I used an abundance of tape for speed but, hot glue will work too.)
Wire (Stranded OR solid core works.)
Amplifier (Yes, you still need the earpiece)
Female 3.5mm (or 2.5mm) female headphone jack (This is if you have a male headphone jack on your earphone and don't want to cut it or if you want to plug it into an amplifier.)
The ceramic earphone can be replaced with a piezo transducer but that would NOT be an earpiece.
Step 2: Build the Solar Assembly
Take your solar panel(s) and wire them in series...skip this if you are using one. Solder two wires from the ends and you are done with the solar assembly.