Digital Audio — Simple as 1, 2, 3

In Uncategorizedby tfwm

I am one of those people that just love to know how things work. I can’t tell you how many fully functioning devices have had their lives cut short prematurely at the end of my screwdriver. Rendered into their individual components, these techno sacrifices would reluctantly give up their techno secrets. Some got put back together while others, well… weren’t so lucky.

Though it may be cool (if not destructive) to understand how things work, it is not absolutely necessary to understand how audio works in order to use it. People utilize analog audio very effectively without ever having to understand the flow of electrons or what is happening in a particular piece of analog gear when you plug into it. However a closer look at digital technology helps us to understand how truly empowering it can be.

To understand even the simplest concepts of audio, digital or analog, we need to start with sound. Sound travels through air in much the same way that waves travel through water. In the case of water, the increase and decrease in the level of the water as the wave goes by is very easy to see with our eyes. This is not the case with sound traveling through air. Although we can’t see the changes in air pressure as a sound wave travels through the air, it is a simple matter to capture these changes with a device called a microphone.

Microphones put out continuously changing electrical signals that exactly correspond to the changes in air pressure as a sound wave travels through the air. When air pressure increases and decreases the electrical signal from the microphone increases and decreases in exactly the same way. Simply put, these varying electrical signals are analog audio.

Digital audio is different from analog audio. Rather than a continuously changing representation of audio like we get in analog, we are dealing with snapshots of time. When the signal from an audio source is connected to an Analog to Digital (AD) Converter, that signal is converted to digital by measuring (or sampling) the audio and storing it as a number. How many times we make these measurements each second is called the sample rate. If we measure an audio signal 100 times in a second, the sample rate is 100. In the case of CD audio, we sample the audio 44,100 times each second for a sample rate of 44.1K. (When you see the suffix K in a sample rate, it indicates that the number is being multiplied by 1000.) This fundamental difference between analog and digital audio is the key to Digital’s power.

Digital audio is just 1’s and 0’s and therein lay the wonder! Since these measurements, or samples, are just numbers representing our audio at a moment of time, it is easy to manipulate them. You see, computers love numbers and we can make computers do all kinds of things when it comes to digital audio. If you want to record it, you just store it on a hard drive like any other digital information. If we want a compressor, we use a program that acts as a compressor. If we want a reverb, we use a program that acts as a reverb. If you need a mixer, buy a program that combines and manipulates these digital numbers just as an analog mixer would combine and manipulate the electrical signals of analog audio.

In the analog world however, you need to actually own all of these individual devices. In the digital world, all you need is one! If you need ten compressors, you launch your compressor program ten times. If you need a reverb that you don’t own, you don’t have to run to the store. You can just try it and buy it online. These digital devices exist virtually on your computer and not in an equipment rack. An additional bonus is that this virtual gear will almost always be less expensive than the real thing.

Another huge benefit of digital is that once an audio signal is converted to digital, it never degrades. This is not the case in the analog world, where every foot of wire, every plug and every analog audio device we run it through does its little part to color or degrade the original signal. Digital audio exists its entire life as numbers which means whatever happens to it, as long as you can still tell what the numbers are, your audio will be unchanged.

Well there is the nickel tour of digital audio. I hope that you at least got a glimpse of how digital audio works. Power, flexibility and audio quality make the decision to use digital as simple as… well, 1,2,3.