How Radio Waves are Different from Sound Waves

The science includes many terms that are difficult to comprehend if we are not someone familiar with them. However, readers of this article will more than likely be familiar with the terms’ sound waves’ and ‘radio waves.

Each is used to describe a method of transmitting either sound or radiofrequency waves, so why are they not the same thing? 

There are great differences between sound waves and radio waves, and that is what we want to explain in this article.

We will begin by looking at what radio waves are and how they travel, and then we’ll do the same with sound waves. By the end, you should understand the fundamental differences between the two, so let’s begin.


What are Radio Waves?

Here’s where it can get a bit confusing. When you turn on the radio, you hear sound in the form of music or speech. Surely that sound you hear consists of radio waves?

It does not! The sound coming out of your radio – transmitted by a speaker – actually consists of sound waves. Let’s try and explain a bit further.

Radio waves are those transmitted from the point of origin – in this case, a radio broadcasting station. When picked up by a receiver – your radio – they are broadcast to you as sound, in sound waves. So, essentially radio waves are what happens before you can hear your favorite songs on the radio.

Radio waves are electromagnetic waves. This means they are a part of what we know as the electromagnetic – or EM – spectrum. You may be surprised to find that many other everyday occurrences are part of the EM spectrum.

What do you mean by this? The EM spectrum includes many examples of electromagnetic radiation – that is, waves that are radiated from a given point.

The spectrum has many different types of EM radiation operating at different wavelengths – the actual size of the wave – and frequencies, which are measured by the number of waves that pass a given point in a certain time – the wave’s frequency.

The EM spectrum includes visible light – the everyday light we can see – as well as Ultra Violet, Infra-Red light, plus gamma rays, and more. Radio waves have the longest wavelengths and exist at the opposite end of the spectrum to gamma rays with the shortest. Now let’s talk a little about how radio waves travel. 

How do Radio Waves Travel?

Radio waves are electromagnetic waves, as opposed to mechanical waves. This means they do not need a physical medium in which to move. They are also transverse waves, meaning the actual wave oscillation is at right angles to the wave’s direction of travel.

Radio waves and radio wave technology, in general, can move through a vacuum and air and can pass through many solid objects.

Radio waves move at a constant speed of around 300,000 km/s in a vacuum and slow down in other mediums. So, you have your radio tuned to the frequency of a particular broadcast at the right wavelength, and the receiver will pick up those precise parameters.

The radio technology converts the signal into movement in the speaker, as sound is delivered as vibration. It has now become a sound wave, so let’s look at those in more detail.

What are Sound Waves? 

Think of sound waves as a distribution of particles caused by vibration. Let’s say you strike a drum with a stick. The drum skin’s vibration reflects the particles that travel until they reach the human ear, which converts these vibrations into what we recognize as sound.

For example, the same is true of a guitar string being plucked or the air being disturbed by a trumpet.

Sound waves are mechanical, not electromagnetic. They are driven by repeated compression of the particles and then the reverse, over and over again. This is the sound we hear.

What we hear depends upon the vibration frequency, which can be anywhere between 200 and 200,000 times per second.

In a standard room at an average temperature, sound waves will travel around 340mps. In solids, they slow down considerably.

How do Sound Waves Travel? 

Unlike the wavelengths of radio waves which are transverse, sound waves are longitudinal. This means the wave travels in the same direction as the molecules. You can see this effect by throwing a stone into a pond, and the waves travel outwards. 

Sound waves – unlike radio waves – must have a medium through which to travel, and in the case of human hearing, this is the air around us. By distorting the air into waves that the human ear recognizes and converts, we hear sound. 

If you read the above carefully a couple of times and compare radio to sound, it’s not as complex as you may believe on first reading. The difference is mainly the mechanical and electromagnetic nature of the waves and how the end-user interprets them – us and the radio receiver.

Let’s see if we can end things by briefly summarizing all of the important points that we have covered in the above sections and giving you a simple explanation of the difference between radio and sound waves.


As we have mentioned a couple of times, the main difference between sound waves and radio waves is that radio waves form a part of the electromagnetic spectrum while sound waves are a mechanical result of physical activity.

This can be the banging of a drum or other musical instrument as described or the speaker’s vibration in your radio or audio system, which drives the particles outwards to the human ear.

It’s as simple as that, and we hope we’ve explained in simple terms how radio waves are converted to sound waves for our pleasure and enjoyment. 

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