Listening to the Radio with the Help of Grass (Video)

Two power plant workers decided to have some fun with a radio frequency transmitting antenna and, risking their lives, recorded themselves listening to the radio using a blade of grass. In this article, we break down what's happening in the video, how singing arcs work, and why this experiment is both amazing and highly dangerous.

You've probably heard unwanted radio interference at some point, often through your stereo speakers when a nearby station leaks in due to poor shielding. Those cases are common, involuntary, and annoying. But plasma speakers or singing arcs offer a different, much more peculiar and dangerous way to generate and hear sound waves. Based on this concept, which we'll explain shortly, some Russian workers started listening to the radio with the help of grass, and there's video evidence.

What are they doing?

Basically, they're creating a circuit that mimics a plasma speaker, which converts air movement and pressure into sound through a high concentration of electric plasma. The transmitter tower carries a massive amount of radio frequency energy (hundreds of watts) flowing through it, so it acts like an electrified pillar. Touch it with bare hands and you won't have to worry about getting a tan that summer.

In fact, you probably won't have to worry about anything else because you'd be burned from the inside in a second. That's why these workers are wearing rubber gloves and using a plant stem or a piece of grass, which is semi-conductive, to let the RF signal pass through them (through the person holding the plant) and then into the ground, completing the circuit.

Sound formation process

The plant starts to heat up and then burns, as seen in the video, reaching temperatures so quickly that they can even burn the hand through an insulating glove, which would be useless for preventing radiation-related cancer. But this sacrifice has its 'reward': when the plant heats up, it ionizes due to the strong RF current and starts to 'sing' in response to that amplitude-modulated radio frequency. In other words, the electric arc formed between the source and the medium becomes modulated by radio frequencies that can pick up signals and transmit them through air vibrations.

What is a singing arc?

Invented by William Du Bois Duddell, a plasma speaker or singing arc is a device that generates a high-voltage electric arc, producing a violet light whose sound seems to sing due to air vibrations. The effect relies on two unique principles. First, ionization of gases causes their electrical resistance to drop significantly, making them extremely efficient conductors, which allows them to vibrate in sympathy with magnetic fields.

Second, the plasma involved, itself an ion field, has relatively negligible mass. As the current frequency varies, the more resistant air remains mechanically coupled and is driven by the vibration of the plasma—more conductive and essentially massless—radiating a potentially ideal reproduction of the sound source. The more electricity fed into the singing arc, the louder the sound, which is why it became part of the first electric musical instrument. Below, a modern homemade model with a CD player as the sound source.

Careful!

First of all, from NeoTeo we do not recommend building singing arcs or plasma speakers, nor approaching such installations as seen in the video. Unlike normal speakers, a plasma speaker is a high-voltage device and therefore very dangerous. The rule you should use is: if you need a tutorial to build a plasma speaker, you don't know enough to be completely safe.

Besides a shock that could be fatal in some cases, if you have a weak heart, use a pacemaker, or any device of that sort, an electric shock could fry you in seconds, so it's not worth the risk. Moreover, the device is dangerous not only to you but also to your electronic equipment. Since a plasma speaker generates high voltages, there's a chance of high-voltage spikes on the low-voltage side of the device, which could enter the audio line and destroy, for example, an audio player.