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» » How Do Audio Files Work? The Basics Explained

Did you know that approximately 40,000 new songs are added to Spotify's libraries every day? Streaming and downloading music has never been easier.

Do you know how audio files work on your computer? Knowing what they are composed of and how they work can help you to know how much disc space or internet bandwidth you need.

Why not take a few minutes to read our in-depth article to find out how music files work on your computer.

The Start of the Digital Era

You likely use digital files every day in the form of mp3 files or even tracks stored on compact discs. you likely switch between digital formats on a regular basis or even convert digital audio files yourself using tools such as the ones on this page: https://setapp.com/how-to/convert-m4a-to-mp3-on-mac.

However, these technologies are actually the digital form of technologies that have been used for a long time.

Radio signals, grooves on a vinyl record were all precursors to the digital music age that we enjoy today. The major change came with the introduction of the computer and in particular the digital converter.

How do digital converters work? Let's find out.

Digital Conversion

In short, a digital converter takes an audio signal and takes tens of thousands of photographs of it. In doing this, it is basically converting it into binary code, or a language that the computer can understand and manipulate.

Although it takes a lot of these pictures, it is not a true replication of the original as there is space in between the snapshots. However, it is of a quality high enough to ensure that the human ear cannot notice this.

The higher the quality the more information it provides to the computer. This is especially important if you plan to manipulate or edit the track later. The quality of the conversion depends on the sample rate. What is this?

Sample Rate

To continue the illustration, the digital converter takes photographs of the audio waveform. Each one of these photographs is actually known as a "sample". The higher the frequency of these samples, also known as the sample rate, the higher the quality of the conversion.

While audio engineers use different sample rates for different purposes, commonly used sample rates include:

  • 44.1 kHz (Equivalent to CD Audio)
  • 48 kHz
  • 88.2 kHz
  • 96 kHz
  • 192 kHz

You will notice that 44.1 kHz is the lowest rate permissible. Why is it limited to this I hear you ask? It is because of the Nyquist-Shannon Sampling Theorem.

The Nyquist-Shannon Sampling Theorem

To correctly record audio, a digital converter must be able to record samples from the full spectrum of human hearing. The spectrum of human hearing is generally considered to be 20Hz – 20kHz.

To be able to accurately represent this, you will need to take at least two photographs or samples from each waveform. One at the top and one at the bottom.

Since the human hearing range is 20 Hz - 20 kHz, to take two samples will require a sample rate of at least 40 kHz. In reality, audio engineers use a slightly higher rate of 44.1 kHz.

This is the limitation placed on the sampling of audio tracks. So the higher the sample rate the better for everyone right? Not exactly.

The Impact of High Sample Rates

High sample rates do provide a better quality of sound and more information for the computer to work with. However, this brings some side-effects that can be considered as drawbacks in certain situations.

The overall size of the file is considerably larger. This means that the speed that the computer can work will be slower. You will need a larger disk space to hold tracks with a high sample rate. To really benefit from tracks with a high sample rate, you should use high-end speakers.

Audio Compression

Once you have created a digital copy of your audio, you then need to decide what format you will use to store and transport it. To convert the file to a type that most media players can work with you, it may need to undergo compression.

In general terms, there are two types of compression that are used. Lossless compression involves bringing the file into a condition where you can play it on media players, but with little or no data loss.

However, engineers perform most audio compression using "lossy" compression. This means that in order to achieve a particular file type and size, some file quality is permitted. Using this form of compression it is possible to shrink audio files in mp3 or AAC format to 1/10th of their original size.

Does Compression Degrade Quality?

If an engineer lowers the size of the file this much, surely the listener will be able to tell the difference? Actually, most people do not notice, and using standard audio equipment it is debatable whether anyone can tell the difference.

This is because engineers employ auditory masking. An engineer in a studio using high-end speakers will likely know the difference between an original audio file and a highly compressed mp3 file.

However, if the engineers have processed the file according to industry standards, it will meet the expectation of the average listener. In short, they will not know the difference. Further, the equipment that the majority of people use will not indicate any missing quality.

The result is that unless you are a true audiophile, you will likely have been listening to audio tracks for many years without knowing that a higher quality exists somewhere in the world.

Everything You Needed to Know About Audio Files and Much More

Whether you streaming downloading or creating audio files it pays to learn a little about the technology behind them. By doing this you can calculate how much disk space you need and your internet bandwidth requirements.

If you would like to know more about audio files and other types of technology, keep reading our blog.

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