Digital audio has been around for many years but was first popularized by the introduction of the CD player in 1982.  Up to that point, most consumers were unaware you could convert the music we heard from vinyl records and tape recordings to a language understood only be a machine.  Digital audio in its raw form is nothing more than a series of bits ( a bit is a two-state on and off marker referred to as 1 and 0), the binary language used by all computers.

How do these bits work and record and playback music?

First, let’s consider how music is expressed in analog terms. When a microphone pickups up sound, it converts it into electricity or voltage. Voltage is what comes out of a battery. So, let us envision that we have a battery with 10 volts available, and that it is hooked up to a microphone (somehow). Let us further envision that when we speak or play music into this microphone, it takes the voltage out of the battery in small or great amounts. Small amounts when we whisper into the microphone, and large amounts when we yell. Therefore, the louder we speak into the microphone, the more voltage is produced out of it (amplitude).

Now, we have a rising and falling level of voltage (amplitude) out of our battery caused by any change in volume of speech into the microphone. Also, this voltage is turning on and off faster when we hit a high note (AC), slower when we hit a lower note, therefore the speed at which this voltage moves (frequency) is determined strictly by the pitch of one’s voice.

Putting it another way, we have a voltage that its bigger and smaller with the level we speak (amplitude): those same voltages are turning on and off (AC) in rythym with one’s speech; and the speed at wh ich those voltages turn on and off (frequency) varies in direct proportion to the pitch of one’s voice.

If we then took this varying voltage and plugged it into a power amplifier that was connected directly to a pair of loudspeakers, we would hear ourselves over those same speakers. And, if we put this varying voltage (the output of our microphone) into a tape recorder, it would record all of these changes in amplitude and frequency so we could play it back later.

OK. Let’s go digital. In its simplest form, we’re going to change the higher and lower voltages into numbers, and then record those numbers. That’s basically it. The rising and falling voltages (amplitude) are electronically measured and those measurements converted to their numeric value, and that numeric value then recorded computer style.

The 1’s and 0’s you hear so much about are merely a counting scheme used to record bigger and smaller numbers. How? By a counting method that is bonehead easy to understand. Let’s use a simple 4 bit system to count, for example, and note the drawing below. There are 3 vertical lines and 16 horizontal lines. Along the top of our box (now full of squares) going in a horizontal direction we’ve marked #‘s 1,2, 4, 8 (one number in each box). These 4 numbers (1,2,4,8) are the digital’meaning’ or representation of the selected squares below. The squares below use ‘X’ and ‘0’ to represent ‘1’ and ‘0’ that we hear so much about. Using only ‘1’s’ and ‘0’s’, let’s start counting in binary fashion.

In the first horizontal row (below our written numbers) note 0,0,0,0 in each of the 4 horizontal squares. This represents zero.

The next row has three ‘0’s’ and one ‘X’. Note the ‘X’ is in the same column as the digital representation for 1 (one).

If we need 3 (three), then we’ll place an ‘X’ in both the ‘1’ and the ‘2’ column. The computer knows to add these two together, so we get ‘3’. Study the chart below and it will become obvious.

See how, using only 1’s and 0’s a computer can count? Instead of a 4 bit system that can only count 16 numbers, 16 and 20 bit and 24 bit systems can count numbers as in the millions.