Earbuds versus Headphones
Before we get started, we should probably make clear the difference between earbuds and headphones. Earbuds refer to the hearing devices that are inserted into the ear, and thus have a very small speaker. Headphones refer to the padded, speakers that sit outside and slightly away from the ear. (Walkman-style headphones are somewhere in the middle, but not really considered here, as we're looking at the extremes.)
Frequency Range versus Apparent Frequency Range, and the Human Ear
Frequency range refers to what frequencies (low to high) an audio output device can emit. Apparent frequency range, however is how your ear hears those frequencies. For example, is the bass too quiet? Are the highest frequencies a little louder? This is really the volume at which a frequency (or more likely a range of frequencies) is perceived.
The human ear is, in youth, capable of perceiving sound from roughly 20 Hz (very low bass sounds) to 20,000 Hz (very high-pitched sounds). Starting in our mid teens, we begin to gradually lose the ability to hear the higher frequencies, as the hairs in our cochleas begin to die. (Interesting side note, we can perceive sound lower than 20 Hz, but we don't hear it, rather, we feel it as vibrations.)
The Problem with Earbuds
Earbuds, as with most audio-emitting devices, are capable of the full range of human-perceptible sounds from 20 - 20,000 Hz. The problem is, those sounds drop off (get much quieter) on the very low, and very high ends. The apparent frequency range becomes smaller.
Conducting a completely non-scientific study, I went out to the Internet looking for specs of various models of earbuds, and headphones. I looked for areas where the volume dropped off on the low end, and on the high end of each, and averaged the results from the earbud category, and those from the headphone category. Here's what I found:
Frequency Ranges
Headphones (average of 5): 28.75 Hz - 14 KHz
Earbuds (average of 5): 176 Hz - 8.2 KHz
From this we see the range is narrower, with earbuds producing less volume of frequencies below 176 Hz, and above 8.2 KHz.
Then, I though about how I might visually demonstrate this loss of fidelity. As it happens, the light we see occurs on a band of perceptible frequencies, as well. With just a little effort, we can map visible light against a spectrum of perceptible audio:
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| Mapping visible light to audible sound. Note that the measurements increase in different directions. This is due to how each is typically measured. Light is measured in the width of a wave (in nanometers), and sound is measured in the number of waves per second (Hz). In both graphs, the longer waves are on the left, as are the fewer number of waves per second. |
Next, we can identify which colors would be missing from an image that is otherwise, fully visible. Using the frequencies above listed for earbuds, we see that much of the red will be missing, as will all of the violet, and darker blues. We need to locate images with a broad spectrum of color, and deep color saturation to see the real effect. I found two that seemed appropriate:
In the image above, the top photograph (analogous to the headphones) shows the full spectrum of colors in the flowers. The bottom picture (analogous to earbuds) removes most of the red (low end of the spectrum), and all of the blue & violet (high end of the spectrum).
The next image shows the same thing, but is a bit more pronounced, as the blue feathers of the parrot are a significant part of the image. The left image is like the headphones, and the right, like the earbuds. Again losing the high frequencies (blue/violet), and lowest frequencies (reds) leaves a washed out image, much like earbuds provide a washed out version of the audio.
Is it a Problem?
Now interestingly, under certain circumstances, this is completely irrelevant. For example, if you are listening to your favorite podcast, there really isn't a need for the higher and lower frequencies, as the human voice when speaking occurs around 300 Hz. Using our visualization process above, it would be the equivalent of starting out with a photograph of grass. Since it's all green anyway, you're just not missing that much. Switch to music, however, and you end up missing much of what the artist intended for you to hear.
