As I began searching out the highest quality and best value audio interfaces available today, I realized something. In order to make the best purchasing decisions for our audio gear, it’s important to have a good understanding of all the factors that go into recording.
One of the items that you’ll often see advertised on audio interfaces is sample rate.
Let’s get into how sample rate fits in to the recording process, then we can talk about whether it should play a part in deciding what audio gear to purchase.
How Audio Gets Converted Into Computer Language
Sound starts out just as pressure waves in the air (or whatever medium it’s traveling through). You can’t store a pressure wave in a computer.
So how do we get audio information saved into a computer to be manipulated?
Turning sound into an electrical signal
Well first, audio must be converted into an electrical signal. Usually this happens by allowing the pressure waves in the air to push a magnet back and forth. The magnet is surrounded by wire and it’s movement creates an electrical signal in the wire which makes its way to the computer.
Recording Quality Alert #1: This is one place where recording quality is determined. The quality of the electrical signal coming from your microphone (or other recording device) can have a noticeable impact on your recordings.
But the story doesn’t end here.
Computers don’t innately understand what to do with an electrical signal. So this signal must be encoded in such a way that the computer can make sense of it.
This is where your audio interface comes into play.
Boosting the electrical signal
Once the natural audio has been converted into an electrical signal it is typically very weak. Often you will want to increase the strength of this signal.
Well, the simplest explanation is that you want to make the audio louder without compromising its quality.
Preamps are designed to do exactly this.
They take an electrical signal and increase its amplitude while (hopefully) adding very little additional electrical noise to that signal.
Great preamps add virtually no additional noise, and bad preamps can add static and distortion to that initial electrical signal.
Recording Quality Alert #2: The presence of a preamp in your audio interface, as well as the quality of the preamp can have a noticeable affect on the quality of your recordings.
Once the signal has been boosted to the desired level, it’s time to start sampling.
Sampling the boosted electrical signal
Let me use a quick analogy. When your computer attempts to recreate photos or videos, it puts a bunch of dots onto your screen. So in order to create a picture, a computer needs data that says how many dots, where those dots go, and what color they are.
When producing videos, a computer needs the same data needed to create a picture just updated as time passes. So as each increment of time passes, the computer displays a new series of dots, and we interpret the series of pictures as a video.
A computer takes a similar approach to recording music.
It takes snapshots of the electrical signal (like a picture) and stores the information in the language of the computer (ultimately 1’s and 0’s).
The process of “sampling” is when your audio interface takes lots of snapshots over time.
Recording Quality Alert #3: Different audio interfaces take different quality snapshots, and the accuracy or quality of these snapshots can have a noticeable effect on the quality of your recordings.
The frequency with which your audio interface takes snapshots is referred to as “sample rate.”
Sample Rate Explained
Simply put, sample rate is how frequently a snapshot is taken of the electrical signal from your audio source. A sample rate of 100 Hertz would mean that 100 snapshots are taken every second.
The industry standard 44.1 kHz (kilohertz) equates to 44,100 snapshots taken every second.
That’s literally all sampling rate is.
Why 44.1 kHz?
The easiest way to think about it is that 44.1 kHz is roughly the sampling rate necessary to record every frequency that can be interpreted by human ears (about 20Hz to 20kHz).
There’s a physical law, called Nyquist’s Theorem, that essentially states that sound waves can be recorded without losing any information as long as they are sampled at a rate of at least twice their frequency.
That means in order to accurately record sounds with a 20Hz frequency, we must sample the sound at a rate of 40 Hz or greater.
And in order to record sounds with 20,000 Hz (20 kHz), we must sample the sound at a rate of 40,000 Hz (40 kHz) or greater.
I’ve heard a few different reasons for using 44.1 kHz. One is a historical one that has to do with how CDs were produced and the way the math worked out for adding audio sampling data to CDs. Another is that 48 kHz was once a professional standard sampling rate and 44.1 kHz was used to create incompatibility between consumer and professional gear.
I’m not 100% sure why 44.1 kHz is the standard today, but it doesn’t really matter to me. I only care about how sample rate affects my recordings.
Does Sample Rate Affect Audio Recording Quality?
Sample rate only affects audio recording quality insofar as it determines what frequencies can be reconstructed without distortion.
So your audio quality will increase as your sampling rate goes from 0 to 40,000 Hz (40 kHz), but any sampling rate above 40 kHz will not improve the quality of your recording.
However, there’s a bit more to the story than that.
When Higher Sampling Rate Can Matter
In today’s age of digital audio, the story doesn’t end after we sample our audio and store it on a computer. In fact, it’s really just the beginning of the story.
After we get a recording saved on our computer, we put it together with other recordings and apply various effects to the recording.
From EQ to delay to reverb to distortion, we push and pull and manipulate our recordings over and over again after they end up in our editing software.
In doing all these things, there can be situations where it’s advantageous to have more than the minimum 2 samples per audio wave cycle.
If you manipulate your raw recordings a lot, then opting for higher sampling rate can make a difference sometimes.
Why I record at 44.1 kHz
There are three reasons that I have rarely bothered recording above the standard 44.1 kHz sample rate:
- Taking more samples per second uses more resources on your computer.
- Recordings with higher sample rate use more storage space on your computer.
- I typically only heavily manipulate recordings I take through MIDI inputs, and MIDI doesn’t care about sample rate
So basically, I just don’t have a need for the higher sample rate 90% of the time, and there’s no reason to put your computer under unnecessary stress and use unnecessary storage space.
So should sample rate play a part in your buying decisions? I think if you are a heavy user of effects and plugins during the mixing/editing phase of recording, then it makes sense to look for an audio interface that allows for a 96 kHz sample rate.
For many, 44.1 kHz will always be enough, but I also believe that part of the joy of recording is experimentation. And sample rate is one more variable to experiment with.