Audio resolution is determined by a combination of sample rate and bit depth. These two variables play a role in different parts of the final recording and ultimately affect the quality of your music.
You will often see audio recording resolution expressed like this: 16-bit/96 kHz.
The first part of this (16-bit) refers to the bit depth, and the second part (96 kHz) refers to the sample rate.
So in order to fully understand audio resolution we must break down both of these variables.
What Is Audio Recording Resolution?
When discussing audio recording resolution, I like to start out with an analogy. Most people are familiar with (and understand) the idea of frame rate and resolution in video. And it happens to be a pretty good analogy for audio resolution.
FPS (frame rate) in video
In video, you often hear the term “fps,” which stands for frames per second.
Video is actually just a series of photographs displayed in quick succession. This concept is familiar to most of us. Watching a video with 24 fps, which is common in movies, looks different than a video with 48 fps.
And when you get to a certain point, you and I can’t tell the difference. Imagine watching something at 2,000 fps and then watching the same scene at 4,000 fps. The two videos would be indistinguishable to us, even though one has twice as many frames in it.
Sample rate equates to FPS (frame rate)
When recording (and playing back) audio, there is a characteristic called sample rate. Sample rate is literally the number of audio snapshots taken per second during recording. It is also the number of audio snapshots that are played back when we listen to audio.
While video can survive on a mere 24 snapshots per second, audio is different. Audio requires thousands of snapshots each second to accurately record sound. In fact, the minimum sample rate required to capture all audible sound (for humans) is 40,000 samples per second.
This is why we typically measure sample rate in kilohertz. 44.1 kHz is the standard sample rate in audio recording.
But even higher sample rates are used sometimes. 48 kHz, 88.2 kHz, 96 kHz and even 192 kHz are all sample rates that you can see in audio recording.
Any recording using a sample rate above 44.1 kHz is called high resolution audio.
Later, we’ll talk about how sample rate can have an impact on the quality of your recording.
Resolution in video (and photography)
Frame rate isn’t the only determining factor in video quality. There’s also resolution.
Each image, or frame, in a video will have a certain number of pixels describing all the information in that image. Each pixel has a location and a color, and that information is all a computer gets to reconstruct that photo.
So a photo with only 4 pixels of information would just be four colors dots. You’ll have a hard time figuring out what the original image was. But if you go up to 100 pixels, then you might have a decent shot. And when you get up to several hundred pixels, most images are easy for us to make sense of.
In video and photography, when we talk about high resolution or high definition, we’re talking about thousands of pixels for each image. And this amount of information isn’t usually necessary unless we want those photos to be blown up to large sizes (or we really want to zoom in on the image).
The concept of high resolution images doesn’t equate particularly well to high resolution audio, but the idea behind it is the same.
Bit depth equates to resolution
We talked about audio recordings taking thousands of samples, or snapshots, of audio in order to later reproduce the original sound.
Just like visual photography resolution, audio snapshots (or samples) can be taken with a certain “resolution” called bit depth.
A bit in computing is just a single data point (a 1 or a 0) and in this analogy it is like a pixel.
A bit depth of 8 means that 8 data points/bits are recorded in each snapshot. Likewise a bit depth of 16 would mean 16 bits are recorded in each snapshot.
This analogy is simplifying the role of a bit, but it’s sufficient to think of a bit as a data point (though this isn’t strictly accurate).
Higher bit depth means a higher resolution, or a more precise recording. You can record more information with more bits, just like you can photograph more information with higher resolution.
Walking through the recording process
Because I’m someone who likes to understand things as deeply as possible (degree in physics), I also like to understand the full process of audio recording.
And I think it’s valuable for all home recording artists to do the same.
So I’m going to walk you through my understanding of how recording works from sound source into your computer recording software.
Here’s the quick breakdown:
- Sound is produced which creates compression waves in the air
- Compression waves enter a microphone
- Inside the microphone is a magnet surrounded by electrical wiring
- Compression waves cause magnet to vibrate
- Magnet’s vibration creates electrical current in the wiring
- Electrical current travels to recording device (audio interface for me)
- (Optional) Electrical current is boosted with a preamplifier
- Recording device takes rapid samples of the electrical current (This process determines audio resolution)
- Sample data is created and passed to the computer
- Computer saves the data to be replayed later
And this is the process of recording into your computer.
There are a few key points that I want to discuss in greater detail.
Step #5 in more detail
During this step the physical sound waves in the air are being converted into an electrical current. The reason I’m highlighting this step is because it’s one of the times where the sound information is being changed in some way.
And any time the sound information is changed, there’s an opportunity to reduce the quality of your final recording.
In this case, a high quality microphone will ensure that most of the sound data makes it to the electrical current. But a lower quality microphone will lose some of that information.
A bad transition of physical sound waves to electrical current can ruin your final recording. Once that sound data is lost there’s no way to get it back.
So to ensure quality recordings it’s essential to use high quality microphones and to use good recording practices.
Step #7 in more detail
Here’s another spot where the sound data is changed. Preamplifiers are used to boost the electrical signal, which is wonderful for recording as long as they don’t change the signal or introduce unwanted noise.
Again, using a good quality preamp can ensure that your sound data remains high quality and that your sampling process is more accurate (it’s easier to measure something big than to measure something small).
Steps #8 and #9 in more detail
Steps 8 and 9 describe the sampling process, and both of these steps change the sound data, which means they introduce chances to change or lose that data.
In step 8 the electrical current is being measured by some piece of hardware. If that hardware is improperly calibrated or takes inaccurate measurements, then the quality of your recording decreases.
Note: this is where the sample rate and bit depth are implemented. A lot of factors are at work during the sampling process and each one can affect the recording quality in different ways.
In step 9 this raw data goes through some software algorithm to transform the data into computer language (1’s and 0’s). If this algorithm is imprecise, then again your audio data can be changed or lost.
This is why having a high quality audio interface is important. The interface usually handles the process of boosting the electrical signal (step 7), measuring the signal (step 8) and encoding that data to computer language (step 9).
So an audio interface carries a huge burden in determining the final recording quality.
How Does Recording Resolution Affect Recording Quality?
You should now understand (reasonably well) what recording resolution is and where it fits into the larger recording process.
So how does the recording resolution actually affect the quality of your recordings?
Well sample rate and bit depth affect different aspects of the recording.
How sample rate affects recording quality
I’ve written an entire article explaining how sample rate affects recording quality, but I’ll run through the highlights quickly.
The full gamut of audio frequencies that humans can hear is between 20 Hz and 20 kHz. So in order to have an accurate recording for human ears, we must be able to record that full range.
There is a theorem in audio recording stating that the two samples must be taken for every time an audio wave completes in order to that audio without losing data.
Simply put, your sampling rate must be at least twice that of the highest audible human sounds.
Since the highest audible human sound is around 20kHz, then our sampling rate must be at least 40 kHz in order to record that frequency.
If your sampling rate is below 40 kHz, then your recording will lose some frequencies of the original sound.
This is the primary reason why the standard sampling rate is 44.1 kHz.
Do higher sample rates create higher quality recordings?
You can find audio interfaces capable of sampling rates up to 192 kHz, but does this actually produce a higher quality recording?
The quick answer is no.
Audio media almost always plays back at 44.1 kHz anyways, so you’d be losing out on any benefits of the higher sample rate during playback.
But there don’t seem to be many benefits of recording above 44.1 kHz anyways.
In some cases you may hear improved performance from your recording plugins during mixing, but the quality of the recording itself will not be improved.
How bit depth affects recording quality
I’ve also written an article discussing how bit depth affects recording quality, but again I’ll highlight the most important points.
Your audio samples are essentially recording the intensity/strength of the electrical signal from your microphone. Higher bit depths allow for more precise measurements of that signal.
Where sample rate affects our ability to record various frequencies, bit depth allows us to record various sound intensities (loudness).
Bit depth ends up determine the dynamic range that can be recorded, where dynamic range is the distance between the loudest and softest sounds we can record.
Low bit depths result in recordings missing the quietest and/or loudest parts of a recording. And higher bit depths allow us to capture quieter and louder sounds.
Do higher bit depths create higher quality recordings?
It’s standard to record at a bit depth of 16, though many audio interfaces can record at 24-bit or even 32-bit depths.
There doesn’t seem to be a practical application for a bit depth of 32, but 24-bit recording can sometimes capture a bit more of the quietest parts of a recording.
This is particularly true when recording live sound. Any time your original sound is exceptionally loud, you could benefit from a higher bit depth.
Higher resolution is harder on your computer
One last piece of information to keep in mind is that using higher sample rates and higher bit depths use more computer resources.
Not only will they make your computer work harder during recording, but the files created will take up more storage space.
A 10 kilobyte audio file recorded at 48 kHz would be 20 kilobytes at 96 kHz, and the same happens when increasing bit depth.
Conclusion
For the most part, in today’s audio industry, an audio recording resolution of 16-bit/44.1 kHz is going to be indistinguishable from anything with a higher resolution.
However, the most enjoyable part of home recording is the process of experimenting. And many audio engineers have found ways to improve small details in their recordings by opting for higher resolutions.
Perhaps you will too.
