What is MP3 – Explained

(The original version of this article was first published on the Mp3 Backing Trax website circa 2006 – 2012)

Before you use mp3, you should fully understand exactly what it is.

MP3 stands for MPEG Audio Layer-3.

In 1987, the Fraunhofer IIS-A started to work on perceptual audio coding. In a joint co-operation with the University of Erlangen, the Fraunhofer IIS-A finally devised a very powerful algorithm that is standardized as ISO-MPEG Audio Layer-3 (IS 11172-3 and IS 13818-3).

Before encoding to mp3, digital audio signals typically consist of 16 bit samples recorded at a sampling rate more than twice the actual audio bandwidth (e.g. 44.1 kHz for Compact Discs). So you end up with more than 1400 K/bit to represent just one second of stereo music in CD quality.

By using MPEG audio encoding, you can shrink down the original sound data from a CD by a factor of 6 (sometimes more) without losing noticeable sound quality. Factors of 10 and even more still maintain a sound quality that is significantly better than you can get by just reducing the sampling rate and the resolution of your samples.

This is obtained by, among other things, perceptual coding techniques addressing the perception of sound waves by the human ear.

Basically, mp3 compresses the audio file by “throwing away” data that your ears can’t hear anyway, and, depending on the bit-rate used, can maintain the original CD sound quality.

By exploiting stereo effects and by limiting the audio bandwidth, the encoding schemes may achieve an acceptable sound quality at even very low bit-rates.

MPEG Layer-3 is the most powerful member of the MPEG audio coding family. For a given sound quality level, it requires the lowest bitrate – or for a given bitrate, it achieves the highest sound quality. In all international listening tests, MPEG Layer-3 has consistently and impressively proved its superior performance above all other compression techniques.

The bit-rate you choose for mp3 encoding has been the subject of much debate and, although you don’t have to worry about any of these technicalities when you buy backing tracks from us (we’ve done all the mp3 encoding for you), we do discuss bit-rates in more depth in our article on MP3 Bit Rates For Backing Tracks.

MP3 audio has many advantages over other music formats and not just because of it’s quality and size. The main advantage to you as a singer, entertainer or musician is that mp3 is kinder to your PA system.

If you’re a singer, you probably use thousands of pounds or thousands of pounds worth of hi-tech musical equipment to play you backing tracks and many singers experience speakers blowing from time to time (which is always costly to repair because most blown speakers can’t be repaired and need to be replaced with new ones).

One of the main causes of damage to speakers is too many frequencies above or below the speakers capacity being pumped through it. This is where mp3 really gains a massive advantage over CD, minidisc and all other formats. You see, the frequencies that mp3 throws away (ie the frequencies that your ears can’t hear – remember we discussed this above), are the very frequencies which damage your speakers!

A horn will blow if you try to pump higher frequencies through it than it can handle.

A bass bin will blow if you try to pump lower frequecncies through it than it can handle.

But if you have encoded your music to mp3, the ultra high frequecncies which the human ear cannot hear will have been removed and, likewise, the lower frequencies which the human ear can’t hear will also have been removed.

This results in cleaner audio and safer frequencies and so helps protect your PA system.