Can we somehow transform the noise wave sounds, from a highway, to electrical energy?
[Physics] Can sound be turned into electrical energy
acoustics
Related Solutions
The humming you hear around all things electrical is 120hz, because an imperfect 60hz sine wave has strong harmonics at 120Hz which you will likely hear over 60Hz because of the frequencies our ears pick up best.
The humming you hear from power supplies, transformers, power meters, high-voltage distribution boxes (which have coils and such inside), etc etc is because the magnetic field in transformer coils is a physical force acting upon ferrous metals (this is how speakers work). Even though you might see a coil consisting of varnished wire that is glued down or epoxied really tight, the magnetic force is still tugging on these wires ever so slightly to great vibration. It doesn't have to be the coil wire itself either, it could be any metal object around the coil. The force is there and it's pushing and pulling on that metal back and forth at 120 times a second.
For high-voltage lines outside on poles, it's a different story. That is, if you aren't around any transformers like you see in those big distribution plots. What you are hearing is not corona discharge (as that is mostly silent unless when you get total breakdown you will hear and see arcing). After rain, or when moisture levels in the air raise you get condensation developing on the ceramic insulators that hold up the cables. You will notice these are shaped oddly like little half-domes so as to make it harder for a stream of water to make a connection between the live line and ground (or another phase). They aren't perfect though, and when rain or moisture develops on them, it can create shorter little paths for the current to travel. What you are hearing is tiny little bursts of water boiling off the insulators.
I think the key here is the question of isotropy of propagation.
The speed of sound in an ideal gas goes as the square root of the temperature. Another way of saying this is that the refractive index for sound waves goes as the inverse square root of temperature. Colder air has a higher refractive index.
At night, it can be the case that the temperature close to the ground is colder than higher up - a temperature inversion. A wave travelling away from the ground will be bent back towards the ground by the decrease in refractive index with height. This (along with the fact it is generally quieter!) can enable you to hear distant events at night.
Best Answer
You could do this, but the amount of energy is too low to be useful.
Even if the noise from the highway was continuous and loud enough to cause long term hearing damage, the sound energy level would only be about 1 milliwatt per square meter. You would need several square meters of sensors even to power a single LED light, which isn't very practical.
Human hearing works on a logarithmic scale of loudness, not a linear one - a typical "noisy crowd of people" environment only has an energy of about 1 microwatt per square meter, and the threshold of human hearing is about 1 picowatt ($10^{-12}$ watts) per square meter.
See http://www.physnet.org/modules/pdf_modules/m203.pdf.