Sound mirrors are some of the most interesting and curious artefacts to be found at any science fair. They are artefacts in which we can hear voices or any sound from a distance, regardless of interference and noise in the environment. Sound mirrors are a practical application of the theories of wave transmission and reception. Today, we will look at how to make sound mirrors to recreate this interesting audio effect.
- Two parabolic dishes (used for satellite or TV reception antennas)
- Two artefacts that will be used as antenna supports.
How to assemble sound mirrors
We start by placing the parabolic dishes at a distance that we consider convenient, we can start with approximately 5 metres and increase the distance as we experiment.
Once the parabolic dishes have been placed at a prudent distance, we must place them facing each other, taking care that the bars used to hold the sensor of each parabolic dish are perfectly aligned with the bar of the other parabolic dish, i.e. we must ensure that the axes of the parabolic dishes are perfectly aligned with each other.
After aligning the parabolic dishes, we are ready to perform our first experience transmitting sound through the air. To do this, we stand close to one of the parabolic dishes and speak into the concave surface of the dish, while another person stands on the other dish and puts his or her ears close to the concave area of the parabolic dish where he or she is standing, this person will be able to hear what the transmitter is saying from a distance. We can see that the parabolic dishes work as a kind of cordless telephone.
How it works
One of the main properties of parabolic objects is that they have the ability to reflect sound waves back to a central focus, similar to the reflection of light in ordinary mirrors.