44.1 kHz: The Magic Number Behind Your Favorite Music

Aug 7, 2023

Imagine you're holding a Compact Disc (CD) - that shiny little disc that revolutionised the way we listened to music. You might be surprised to learn that one of the keys to the crisp, clear sound that comes from a CD (and from digital music in general) is hidden in a magic number: 44.1 kHz. But what does this number mean, and why is it so important?

In simple terms, 44.1 kHz, or 44,100 samples per second, is like the 'heartbeat' of most digital audio. Every second, the audio is sampled 44,100 times to accurately represent the sounds that make up your favourite songs. This sample rate has become the global standard in music production, but it didn't always hold this prestigious status.
When digital recording was still in its 'baby' phase back in the 1970s, there was a bit of a 'Wild West' scenario going on. Different companies used different sample rates, including 37kHz and 50 kHz, like a musical version of the Metric versus Imperial system battle. Then, two tech heavyweights, Philips and Sony, decided to collaborate and create the Compact Disc, and the musical landscape began to harmonise.

Choosing a standard sample rate for the CD wasn't as simple as picking a number out of a hat. It was more like choosing a team captain – the number had to be capable, versatile, and widely accepted. In the end, 44.1 kHz was the 'chosen one', for a number of interesting reasons.

According to the Nyquist theorem (don't worry, we're not going to delve into mathematics), a 44.1 kHz sample rate allows us to recreate all the sounds that fall below 22.05 kHz. Why is this important? Because it covers all the sounds that the average person can hear. Although some audiophiles debate the perception of even higher frequencies, most of us can't distinguish any tones above 20 kHz.

Another reason behind the selection of 44.1 kHz was the amount of music it could fit on a 120-millimetre disc. It allowed over 80 minutes of music to be recorded, which was a real crowd-pleaser as it surpassed what a vinyl LP record could hold. It was like upgrading from a small backpack to a suitcase – suddenly, you could carry more with you.
The number 44,100 also has some 'math magic' in it. Its factors, 2x2x3x3x5x5x7x7, make 44.1kHz a dream for many mathematical calculations. This can be particularly handy when it comes to audio processing, like adjusting the volume or adding effects to a track.

Fast forward to today, and this 'magic number' still plays a crucial role in the world of music. Whenever you press play on your favourite digital song, you're listening to the legacy of 44.1 kHz - the heartbeat that keeps the music alive.

Author - Prof. Josh Reiss.