In our post on active noise cancellation, we made many references to the fact that sound exists in the form of waves, but what does that actually mean? What is it that’s waving when sound travels from a speaker or headphone to your ears? After all, it’s not as if there are threads running through the air from point to point, like the ones we’ll be using on this post to explain sound waves and music.
The wiggles in the image above represent electrical signals. Higher and lower peaks and valleys represent higher and lower voltages. Another way to think of those wiggles is as representations of higher and lower pressure, because that’s what sound waves are.
Those electrical signals are converted by speakers or headphones into vibrations that push and pull the air, bunching up the air molecules or thinning them out. More molecules of air bunched up into the same amount of space equals high pressure. Fewer molecules thinned out in the same amount of space equals low pressure. And those alternating waves of high and low pressure are what make up the sounds we hear.
How sound waves are converted into electrical signals?
You can see below a rough visualization of how electrical waveforms translate into soundwaves. It’s not a perfect representation, because a static image can’t convey one of the most important aspects of sound waves in music: time. But imagine each of the little blue dots in the image as a molecule of air, and imagine each of the pressurized groups of molecules traveling from left to right as they bump into one another, and you start to get the picture. It’s a little more complicated, but this is close enough for a basic understanding.
As you can see in this image, higher peaks in the waveform translate into higher pressure in the air. Roughly speaking, the way we perceive this is as louder sounds. The rate at which these waves of pressure reach our eardrums and make them wiggle is also translated into the pitch of the sound. Waves of roughly equal pressure that reach our eardrums with greater frequency (say, 500 to 5,000 times per second) are perceived as high-pitched sounds, like the sound of a piccolo. Waves of roughly equal pressure that reach our ears with relatively lower frequency (say, 30 to 60 times per second) are perceived as low-pitched sounds, like the lowest notes on a bass guitar.
This way of visualizing sound may also help you better understand how things like active noise cancellation work. Think of it like this: higher-than-normal air pressure plus lower-than-normal air-pressure equals normal sound pressure—in other words, no sound.
Is music a noise?
It also helps to explain why noise interferes with our music-listening pressure. When comparing noise vs music, you can think of noise as random pressurization of the air, with little to none of the regularity that helps us perceive high- and low-frequency sounds, and everything in between.
In visual terms, that noise, when added to the signal from above, might look something like this if we could see each individual molecule of gas in the air around us:
Translate that into sound, and you can see that you’re losing out on a lot of the “quieter” parts of the signal, and a lot of the definition in the music overall. Our natural tendency is to turn up the music to overcome that noise. But remember, we’re talking about air pressure here. The louder you play it, the more pressure you’re subjecting your eardrums to, and the more you’re stressing the little hair cells inside your cochlea. The result can quickly become physical damage, resulting in hearing loss.
Minimize noise with active noise cancelation
So, treat your ears kindly. Try to minimize noise as much as you can when listening to music through active noise cancellation found on models like the Curve BT 120 NC water resistant wireless earphones or BT 150 NC wireless earphones with touch interface, and even true wireless earphones like the BOLT BT 700, which features a charging speaker case that doubles as a speaker. Either way, you’ll know for sure that the sound waves reaching your ears are the ones you want to hear.
By Dennis Burger