As an engineer or producer, you deal with digital audio every day. However, understanding its inner workings can often lead to confusion due to overly elaborate explanations and complex calculations. In this post, we will take a look at digital audio in an easy-to-understand way and understand why it is important to your productions.
Before a digital system can understand the audio you feed into it, it must translate it into a language it can understand. In its most fundamental state, data in a computer is made up of ones and zeros. A digital system must take snapshots of the analog audio to process it in a way it understands.
Each snapshot is made up of a single number, and there are two parameters that determine the quality of the captured audio: sample rate and bit depth. Sample rate is how many snapshots of the original signal the computer takes in the course of a single second, described in kilohertz. Bit depth determines the amount of possible amplitude values we can record for each sample.
If your DAW is set to record at 24-bit, then it can take snapshots of the incoming audio with more accuracy than if it were set to 16-bit. The higher the bit depth, the greater the detail in the audio, and the same is true for the sample rate.
Sample rate is how often the computer takes a snapshot of the analog audio. To accurately capture and play back pitch, we need to measure the wave at least twice per cycle. It is generally accepted that the human hearing range goes up to around 20 kilohertz, so we need to capture the audio at least at 40 kilohertz to work with audio that goes all the way up to the highest frequency that we can hear.
Using 44.1 kilohertz instead of 40 kilohertz allows the low pass filter to have a gentler slope. This is true for almost any sample rate. Audio above half the sample frequency is filtered, and higher sample rates can capture higher frequencies and give the listener higher definition when it matters.
For delivery formats, 44.1 kilohertz has been a standard for audio-only formats, and 48 kilohertz when distributing audio that accompanies video. Higher sample rates can be useful for certain kinds of audio signal processing and also when you know you’re going to want to get creative with the audio you’re recording.
With a firmer understanding of audio sample rate and audio bit depth, you can understand some of the reasons behind why we do what we do in audio engineering. Digital audio offers us a myriad of possibilities for manipulating audio, so always record at a sample rate of at least 44.1 kilohertz and a minimum of 24 bits, and you’re sure to get audio that sounds great every time.