Subject: How can transform low voltage from a earphone output to light a bulb?

I want to build a device to monitor noice levels. Radio Shack have a 
noisemeter that allow one to monitor for noises above a preset Db 
level, you can read the Db level or listen by using earphones. I want 
to use that signal to power a visible light bulb at least the size of 
a flash light bulb. Can you help me on this? thanks.

Re: How can transform low voltage from a earphone output to light a bulb?